JP7672130B2 - Fluid Dispensing System - Google Patents

Description

The present invention relates to a fluid discharge system that supplies a fluid to a discharge device and discharges it.

Conventionally, pump devices have been provided that can pump up and pump out fluids prepared in a container such as a pail can, such as the pump device disclosed in Patent Document 1 below. Conventionally, fluid discharge systems have also been provided that are formed by connecting such pump devices to a discharge device such as a dispenser via piping. The fluid discharge system supplies the fluid pumped by the pump device to the discharge device, thereby enabling the fluid to be discharged from the discharge device.

JP 2019-203465 A

The above-mentioned fluid discharge system can continue to discharge the fluid from the discharge device as long as the prepared fluid remains in the container of the pump device. However, when the prepared fluid on the pump device side runs out, the supply of fluid to the discharge device stops. Therefore, the above-mentioned fluid discharge system needs to temporarily stop the discharge of the fluid from the discharge device and replenish the pump device with fluid, etc., every time the fluid runs out of the container of the pump device.

The inventors therefore considered preparing multiple (e.g., two) pump devices for one discharge device in a fluid discharge system, and making it possible to switch between pump devices capable of supplying fluid to the discharge device as needed. As a result, they discovered that a fluid discharge system configured in this way can switch the connection of the discharge device to a pump device that is ready for fluid when the pump device connected to the discharge device runs out of fluid, minimizing the interruption of discharge of fluid. However, they discovered that such a configuration would pose problems such as the need for a large installation space and high costs due to the need to provide multiple (e.g., two) pump devices for one discharge device.

The present invention aims to provide a fluid discharge system that can stably supply fluid to a discharge device while minimizing increases in installation space and costs.

(1) The fluid discharge system of the present invention comprises a discharge device that discharges a fluid, a pump having a storage section and capable of supplying the fluid to the discharge device by pumping the fluid stored in the storage section, a supply path connecting the pump and the discharge device so that the fluid can pass between them, a buffer tank that is positioned midway through the supply path and capable of sucking and discharging the fluid, and a remaining amount grasping section that grasps the remaining amount of fluid in the discharge device, and is characterized in that the operation of the buffer tank is controlled based on the remaining amount of fluid grasped by the remaining amount grasping section.

The fluid discharge system of the present invention includes a pump capable of supplying fluid to the discharge device, as well as a buffer tank capable of sucking in and discharging fluid. Therefore, the fluid discharge system of the present invention can suck in and store fluid in the buffer tank, and then discharge and supply the fluid from the buffer tank at appropriate times. Therefore, the fluid discharge system of the present invention can operate the pump and buffer tank in a complementary manner, and steadily supply fluid to the discharge device.

The fluid discharge system of the present invention can also control the operation of the buffer tank based on the remaining amount of fluid in the discharge device ascertained by the remaining amount ascertaining section. Therefore, the fluid discharge system of the present invention can control the suction and discharge operations of the fluid in the buffer tank to be performed appropriately according to the remaining amount of fluid in the discharge device. Therefore, the fluid discharge system of the present invention can minimize the risk of a shortage or excess of fluid remaining in the discharge device.

The fluid discharge system of the present invention can stably supply fluid to the discharge device by the above-mentioned operation without providing multiple pumps. Therefore, the fluid discharge system of the present invention can suppress increases in installation space and costs compared to a configuration with multiple pumps.

(2) In the fluid discharge system of the present invention, it is preferable that the remaining amount grasping unit includes a pressure detection device provided between the buffer tank and the discharge device in the supply path or in the discharge device, and grasps the remaining amount of fluid in the discharge device based on the measurement value of the pressure detection device.

With this configuration, the remaining amount of fluid in the discharge device can be properly grasped based on the pressure detected by the pressure detection device. Therefore, with the fluid discharge system of the present invention, the pump and buffer tank are operated appropriately according to the remaining amount of fluid in the discharge device, and the fluid can be appropriately and stably supplied to the discharge device so that there is no shortage or excess of fluid remaining in the discharge device.

(3) The fluid discharge system of the present invention is preferably capable of continuing to supply fluid to the discharge device by discharging fluid from the buffer tank when the supply of fluid by the pump is restricted.

The fluid discharge system of the present invention can compensate for the reduction in supply capacity due to the restriction of fluid supply by the pump by discharging the fluid through the buffer tank. Therefore, even in cases where the fluid discharge system of the present invention is forced to restrict the supply of fluid by the pump due to a lack of fluid remaining in the pump, for example, it can stably supply fluid to the discharge device in an appropriate manner so that the discharge device does not run out of fluid.

(4) When supplying fluid to the discharge device, the fluid discharge system of the present invention may preferably perform either one or both of the following: the buffer tank discharges the fluid when the remaining amount of fluid in the discharge device ascertained by the remaining amount grasping unit falls below a predetermined lower limit; and the buffer tank stops discharging the fluid when the remaining amount of fluid in the discharge device ascertained by the remaining amount grasping unit exceeds a predetermined upper limit.

The fluid discharge system of the present invention can realize a stable supply of fluid to the discharge device by discharging fluid from the buffer tank on the condition that the remaining amount of fluid in the discharge device falls below a predetermined lower limit when supplying fluid to the discharge device. Specifically, even in cases where the supply of fluid by the pump has to be restricted due to a lack of fluid remaining in the pump, for example, the fluid discharge system of the present invention can supply fluid from the buffer tank to the discharge device when the remaining amount of fluid in the discharge device falls below a predetermined lower limit, thereby preventing the occurrence of a lack of fluid remaining in the discharge device.

The fluid discharge system of the present invention can also prevent an excessive supply of fluid to the discharge device by having the buffer tank stop discharging the fluid when the remaining amount of fluid in the discharge device exceeds a predetermined upper limit. This can prevent problems such as unstable supply pressure, discharge pressure, and discharge amount of fluid in the discharge device.

(5) In the fluid discharge system of the present invention, the buffer tank is capable of accumulating the fluid inside the buffer tank by sucking the fluid, and the discharge device continues to discharge the fluid while the fluid is being accumulated.

The fluid discharge system of the present invention can continue to discharge the fluid from the discharge device even while the fluid is accumulating in the buffer tank. Therefore, the fluid discharge system of the present invention can minimize the decrease in productivity caused by, for example, stopping the discharge of the fluid from the discharge device due to the accumulation of the fluid in the buffer tank.

(6) The fluid discharge system of the present invention may be configured such that, when accumulating fluid in the buffer tank, the buffer tank sucks in the fluid on condition that the remaining amount of fluid in the discharge device ascertained by the remaining amount grasping unit exceeds a predetermined upper limit, and the buffer tank stops sucking in the fluid on condition that the remaining amount of fluid in the discharge device ascertained by the remaining amount grasping unit falls below a predetermined lower limit, or both.

The fluid discharge system of the present invention allows the buffer tank to suck in the fluid on the condition that the remaining amount of fluid in the discharge device exceeds a predetermined upper limit, thereby making effective use of the period when it is not necessary to supply fluid to the discharge device, and sucking in and storing the fluid in the buffer tank. In addition, by doing this, the fluid discharge system of the present invention can prevent an excessive supply of fluid to the discharge device when it is not necessary to supply fluid to the discharge device. This can prevent problems such as unstable supply pressure, discharge pressure, and discharge amount of fluid in the discharge device.

In addition, the fluid discharge system of the present invention is configured so that the buffer tank stops sucking the fluid when the remaining amount of fluid in the discharge device falls below a predetermined lower limit, and therefore, when the remaining amount of fluid in the discharge device is decreasing, the fluid can be supplied to the discharge device preferentially over the buffer tank. This allows the fluid discharge system of the present invention to suppress the occurrence of discharge defects due to a lack of remaining fluid. The remaining amount of fluid in the discharge device can be determined, for example, by directly measuring and deriving the amount using a remaining amount sensor provided in the discharge device, or by detecting and subtracting the amount of fluid flowing into and out of the discharge device, and the amount of fluid can be directly or indirectly derived and determined, or indirectly determined by the time it takes for the fluid to flow in and out of the discharge device.

(7) In the fluid discharge system of the present invention, the buffer tank is capable of accumulating the fluid inside the buffer tank by sucking in the fluid, and when the supply of fluid by the pump is restricted, the buffer tank is capable of discharging the fluid accumulated inside, thereby enabling the supply of fluid to the discharge device to be continued, and it is preferable that the operation of the buffer tank is controlled based on the remaining amount of fluid in the discharge device ascertained by the remaining amount grasping unit, both for accumulating the fluid and for supplying the fluid.

The fluid discharge system of the present invention is capable of continuously supplying fluid to the discharge device by discharging the fluid accumulated inside the buffer tank when limiting the supply of fluid by the pump. In addition, the operation of the buffer tank is controlled based on the remaining amount of fluid in the discharge device for both accumulating fluid and supplying fluid. Therefore, the fluid discharge system of the present invention operates the pump and the buffer tank in a complementary manner, enabling a stable supply of fluid to the discharge device.

(8) In the fluid discharge system of the present invention, the buffer tank, when accumulating the fluid, performs at least one of the following operations: sucking the fluid on condition that the remaining amount of the fluid in the discharge device grasped by the remaining amount grasping unit exceeds a predetermined first upper limit value, and stopping the suction of the fluid on condition that the remaining amount of the fluid in the discharge device grasped by the remaining amount grasping unit falls below a predetermined first lower limit value, and, when supplying the fluid, performs at least one of the following operations: discharging the fluid on condition that the remaining amount of the fluid in the discharge device grasped by the remaining amount grasping unit falls below a predetermined second lower limit value, and stopping the discharge of the fluid on condition that the remaining amount of the fluid in the discharge device grasped by the remaining amount grasping unit exceeds a predetermined second upper limit value.

The fluid discharge system of the present invention controls the accumulation of fluid in the buffer tank based on a first upper limit value and a first lower limit value for the remaining amount of fluid in the discharge device. Specifically, the fluid discharge system of the present invention can accumulate fluid in the buffer tank when the remaining amount of fluid in the discharge device exceeds the first upper limit value, and can stop accumulation of fluid in the buffer tank when the remaining amount of fluid in the discharge device falls below the first lower limit value. Therefore, the fluid discharge system of the present invention can accumulate fluid in the buffer tank at an appropriate time depending on the remaining amount of fluid in the discharge device.

The fluid discharge system of the present invention also controls the discharge of fluid from the buffer tank based on a second upper limit value and a second lower limit value for the remaining amount of fluid in the discharge device. Specifically, the fluid discharge system of the present invention can discharge the fluid and supply it to the discharge device when the remaining amount of fluid in the discharge device falls below the second lower limit value, and can stop the discharge of the fluid and stop the supply to the discharge device when the remaining amount exceeds the second upper limit value. Therefore, the fluid discharge system of the present invention can discharge the fluid from the buffer tank at an appropriate time depending on the remaining amount of fluid in the discharge device.

The amount of fluid remaining in the discharge device can be determined, for example, by directly measuring and deriving the amount using a remaining amount sensor provided in the discharge device, by detecting the amount of fluid flowing into and out of the discharge device and subtracting the other amount to directly or indirectly derive the amount of fluid, or by indirectly determining the amount of fluid flowing in and out of the discharge device based on the time it takes for the fluid to flow in and out of the discharge device.

(9) The fluid discharge system of the present invention is preferably characterized in that the buffer tank is equipped with a position variable member whose position varies within a predetermined range depending on the amount of fluid remaining, and a detection device that detects the position of the position variable member, and the amount of fluid remaining in the buffer tank can be determined based on the correlation between the capacity of the buffer tank and the position of the position variable member.

This configuration allows the remaining amount of fluid in the buffer tank to be continuously detected. In addition, the above-mentioned configuration allows the upper and lower limits of the amount of fluid stored in the buffer tank to be set or changed as appropriate, thereby controlling the operation of the fluid discharge system.

The present invention provides a fluid discharge system that can stably supply fluid to a discharge device while minimizing increases in installation space and costs.

FIG. 1 is a schematic diagram showing an example of a fluid discharge system of the present invention. FIG. 2 is a cross-sectional view showing an example of a discharge device used in the fluid discharge system of FIG. 1. 2A is a cross-sectional view showing the configuration of a buffer tank used in the fluid discharge system of FIG. 1 in a pressurized state, and FIG. 2B is an enlarged cross-sectional view of a main portion of FIG. 2 is a cross-sectional view showing the configuration of a buffer tank used in the fluid discharge system of FIG. 1 in a reduced pressure state. FIG. 2 is a cross-sectional view showing the configuration of a buffer tank used in the fluid discharge system of FIG. 1 in a retaining state. 4A and 4B are explanatory diagrams illustrating the operating states of the various parts of the fluid discharge system of FIG. 1 when the supply pressure is high and when the supply pressure is low in a pump supply mode, respectively. 2 is a timing chart of the fluid delivery system of FIG. 1 operating in a pump supply mode. 2 is a flow chart of the fluid delivery system of FIG. 1 operating in a pump feed mode. 4A and 4B are explanatory diagrams illustrating the operating states of the various parts of the fluid discharge system of FIG. 1 when the supply pressure is high and when the supply pressure is low in the tank accumulation mode, respectively. 2 is a timing chart of the fluid dispensing system of FIG. 1 operating in a tank accumulation mode. 2 is a flow chart of the fluid dispensing system of FIG. 1 operating in a tank accumulation mode. 5A and 5B are explanatory diagrams illustrating the operating states of the various parts of the fluid discharge system of FIG. 1 when the supply pressure is high and when the supply pressure is low in the tank supply mode, respectively. 2 is a timing chart of the fluid dispensing system of FIG. 1 operating in a tank supply mode. 2 is a flow chart of the fluid dispensing system of FIG. 1 operating in a tank supply mode. 4A and 4B are explanatory diagrams illustrating the operating states of the various parts of the fluid discharge system of FIG. 1 when the supply pressure is high and when the supply pressure is low in the composite supply mode, respectively. 2 is a timing diagram of the fluid dispensing system of FIG. 1 operating in a multiple delivery mode; 2 is a flow chart of the fluid dispensing system of FIG. 1 operating in a multiple delivery mode. 2 is a flow chart of the fluid dispensing system of FIG. 1 operating in a first mode of operation. 2 is a timing chart of the fluid dispensing system of FIG. 1 operating in a first operating mode. 2 is a flow chart of the fluid dispensing system of FIG. 1 operating in a second mode of operation. 1. FIG. 4 is a cross-sectional view of a modified example of a buffer tank used in the fluid discharge system of FIG. 1. FIG. 4 is a cross-sectional view of a main portion of a modified example of a buffer tank used in the fluid discharge system of FIG. 1. FIG. 4 is a cross-sectional view of a main portion of a modified example of a buffer tank used in the fluid discharge system of FIG. FIG. 13 is an explanatory diagram showing an example in which a detection device capable of continuously detecting the amount of fluid stored in a buffer tank is provided. 11A-11C are image diagrams of an example of a user interface showing the amount of fluid stored in the buffer tank and the operating mode of the fluid dispensing system.

The following describes in detail a fluid discharge system 10 according to one embodiment of the present invention with reference to the drawings. In the following description, the configuration of the fluid discharge system 10 will be described first, and then the operation of the fluid discharge system 10 will be described.

<Configuration of fluid discharge system 10>
As shown in Fig. 1, the fluid discharge system 10 is configured by connecting a pump 20 and a discharge device 30 with a supply path 40. The fluid discharge system 10 is configured by providing a buffer tank 50 in the middle of the supply path 40. The fluid discharge system 10 also includes a remaining amount grasping unit 90 for grasping the remaining amount of fluid in the discharge device 30. The fluid discharge system 10 also includes a control device 200 for controlling the operation of the pump 20, the discharge device 30, and the buffer tank 50. The fluid discharge system 10 can discharge the fluid supplied by the pump 20 and the buffer tank 50 toward a workpiece in the discharge device 30.

The pump 20 is a device for pumping up and pumping fluid from the storage section 22 where the fluid is stored. The pump 20 is connected to the supply line 40 via piping. Therefore, the fluid pumped up from the storage section by the pump 20 can be pumped to the discharge device 30 via the supply line 40.

The discharge device 30 is configured by a rotary volumetric pump. In this embodiment, the discharge device 30 is configured by a so-called uniaxial eccentric screw pump. As shown in FIG. 2, the discharge device 30 is configured to house a rotor 102, a stator 104, a power transmission mechanism 106, etc. inside a casing 100. The casing 100 is a metallic cylindrical member, and a first opening 110 is provided at one end in the longitudinal direction. In addition, a second opening 112 is provided on the outer periphery of the casing 100. The second opening 112 is connected to the internal space of the casing 100 at an intermediate portion 114 located in the longitudinal middle portion of the casing 100.

The first opening 110 and the second opening 112 are parts that function as the suction port and the discharge port of the uniaxial eccentric screw pump that constitutes the discharge device 30. The discharge device 30 can make the first opening 110 function as the discharge port and the second opening 112 function as the suction port by rotating the rotor 102 in the forward direction. Also, the first opening 110 can function as the suction port and the second opening 112 as the discharge port by rotating the rotor 102 in the reverse direction.

The stator 104 is a member having a generally cylindrical exterior shape formed from an elastic body such as rubber, or from a resin, etc. The inner peripheral wall 116 of the stator 104 has an n-thread single-stage or multi-stage female thread shape. In this embodiment, the stator 104 has a two-thread multi-stage female thread shape. In addition, the through-hole 118 of the stator 104 is formed so that its cross-sectional shape (opening shape) is generally elliptical when viewed in cross section at any position in the longitudinal direction of the stator 104.

The rotor 102 is a metallic shaft body, and has a single-stage or multi-stage male thread with n-1 threads. In this embodiment, the rotor 102 has a single-stage eccentric male thread. The rotor 102 is formed so that its cross-sectional shape is a nearly perfect circle when viewed in cross section at any position in the longitudinal direction. The rotor 102 is inserted into the through-hole 118 formed in the stator 104 described above, and is free to rotate eccentrically inside the through-hole 118.

When the rotor 102 is inserted into the stator 104, the outer peripheral wall 120 of the rotor 102 and the inner peripheral wall 116 of the stator 104 are in close contact with each other at their tangents, and a fluid transport path 122 (cavity) is formed between the inner peripheral wall 116 of the stator 104 and the outer peripheral wall 120 of the rotor 102. The fluid transport path 122 extends in a spiral shape in the longitudinal direction of the stator 104 and the rotor 102.

When the rotor 102 is rotated in the through hole 118 of the stator 104, the fluid transport path 122 advances in the longitudinal direction of the stator 104 while rotating within the stator 104. Therefore, when the rotor 102 is rotated, the fluid is sucked into the fluid transport path 122 from one end side of the stator 104, and the fluid is transported toward the other end side of the stator 104 while being confined within the fluid transport path 122, and can be discharged at the other end side of the stator 104. Specifically, when the rotor 102 is rotated forward, an operation of sucking in a fluid from the second opening 112 and discharging it from the first opening 110 (discharge operation) can be performed. In addition, by rotating the rotor 102 in the reverse direction, an operation of sucking in a fluid in the opposite direction to the discharge operation, that is, from the first opening 110 side toward the second opening 112 side (pull-back operation) can be performed.

The power transmission mechanism 106 is for transmitting power from the driving machine 124 to the rotor 102 described above. The power transmission mechanism 106 has a power transmission section 126 and an eccentric rotation section 128. The power transmission section 126 is provided at one end side of the longitudinal direction of the casing 100. The eccentric rotation section 128 is provided at the intermediate section 114. The eccentric rotation section 128 is a section that connects the power transmission section 126 and the rotor 102 so that power can be transmitted. The eccentric rotation section 128 is provided with a connecting shaft 130 that is formed of a conventionally known coupling rod, a screw rod, or the like. Therefore, the eccentric rotation section 128 can transmit the rotational power generated by operating the driving machine 124 to the rotor 102 and rotate the rotor 102 eccentrically.

The supply path 40 is a flow path that connects the pump 20 and the discharge device 30 so that the fluid can pass between them. A buffer tank 50, which will be described in detail later, is provided in the middle of the supply path 40. Specifically, the supply path 40 has a primary supply path 42 that connects the primary side of the buffer tank 50 (the upstream side of the supply path 40 in the direction of the fluid flow) and the pump 20, and a secondary supply path 44 that connects the secondary side of the buffer tank 50 (the downstream side of the supply path 40 in the direction of the fluid flow) and the discharge device 30.

In the middle of the supply path 40, a sensor 92 constituting a remaining amount grasping unit 90, which will be described in detail later, and a valve 48 are provided. The sensor 92 can be, for example, a pressure gauge or a flow meter, capable of detecting the state of the fluid in the supply path 40. In this embodiment, the sensor 92 is a pressure gauge. The sensor 92 is disposed in the supply path 40 between the discharge device 30 and the buffer tank 50. In addition, the valve 48 is disposed in the supply path 40 between the pump 20 and the buffer tank 50. The valve 48 is capable of restricting (blocking in this embodiment) the flow of the fluid from the pump 20 to the discharge device 30. The valve 48 may be configured as a so-called two-way valve, a check valve, or the like.

The buffer tank 50 is disposed midway through the above-mentioned supply path 40. The buffer tank 50 is capable of sucking and discharging fluid. The buffer tank 50 can accumulate fluid inside by sucking in the fluid. When the pump 20 stops supplying the fluid, the buffer tank 50 discharges the accumulated fluid inside, thereby enabling the supply of the fluid to the discharge device 30 to continue. The operation of the buffer tank 50 is controlled by the control device 200 according to the remaining amount of fluid in the discharge device 30. As shown in Figures 3 to 5, the buffer tank 50 has a tank portion 52 and a volume fluctuation mechanism 54.

The tank section 52 is capable of allowing a fluid to flow in and out of the supply path 40. In this embodiment, the tank section 52 is provided with a connection section 56 on one end side of a tubular (in this embodiment, substantially cylindrical) tank main body section 52a extending in a predetermined axial direction, and a communicating space 58 and a non-communicating space 60 are provided inside the tank main body section 52a.

The connection part 56 is provided on one axial end side of the tank body part 52a that constitutes the tank part 52. The connection part 56 is a part that is connected to the supply path 40. The connection part 56 has a flow path 56a that extends in a direction that intersects with the axial direction of the tank part 52 (in the present embodiment, the radial direction). The connection part 56 has connection ports 56b, 56c at both ends of the flow path 56a. The connection ports 56b, 56c open at the periphery of the tank part 52 and can be connected to the piping that constitutes the supply path 40. The connection part 56 also has a communication hole 56d in the radial middle part of the tank part 52. The tank part 52 is in communication with the flow path 56a and the internal space (communication space 58) of the tank body part 52a via the communication hole 56d.

The communication space 58 is a space provided on the side of the tank section 52 where the connection section 56 is provided. The communication space 58 is formed to communicate with the supply path 40 via the connection section 56 described above. Therefore, the tank section 52 is capable of sucking and discharging fluid into and from the communication space 58 between the tank section 52 and the supply path 40 connected to the connection section 56.

The non-communicating space 60 is a space that is not connected to the supply path 40. The non-communicating space 60 is a space adjacent to the communicating space 58 in the axial direction of the tank section 52 on the opposite side of the connecting section 56 to the communicating space 58. The non-communicating space 60 is separated from the communicating space 58 by a piston section 62 (partition section) of the volume fluctuation mechanism 54, which will be described in detail later. The volume fluctuation mechanism 54 is connected to an end of the non-communicating space 60. As a result, the non-communicating space 60 is connected to a casing 68 that constitutes the drive section 64 of the volume fluctuation mechanism 54.

The volume fluctuation mechanism 54 is an operating mechanism that varies the volume of the communicating space 58 in the tank portion 52. The volume fluctuation mechanism 54 has a piston portion 62 and a drive portion 64, and can move the piston portion 62 in the axial direction of the tank portion 52 inside the tank portion 52 by using the drive portion 64. Therefore, the volume fluctuation mechanism 54 can change the volume (volume ratio) of the communicating space 58 and the non-communicating space 60 inside the tank portion 52 by changing the position of the piston portion 62 by using the drive portion 64.

The piston portion 62 separates the interior of the tank portion 52 into a communicating space 58 and a non-communicating space 60. In this embodiment, the piston portion 62 is a piston. The outer diameter of the piston that constitutes the piston portion 62 is approximately the same as the inner diameter of the tank portion 52. A seal member 62a is attached to the outer periphery of the piston portion 62. As a result, the piston portion 62 separates the internal space of the tank main body portion 52a into a communicating space 58 and a non-communicating space 60 while sealing to prevent leakage of liquids, including fluids, and gases.

The driving unit 64 is for moving the piston portion 62 in the axial direction inside the tank main body portion 52a. The driving unit 64 has a rod portion 66, a casing 68, a partition wall 70, and an intake and exhaust device 72. The rod portion 66 is inserted into the tank main body portion 52a from the non-communicating space 60 side. The rod portion 66 is arranged so as to extend in the axial direction of the tank main body portion 52a. The piston portion 62 is connected to one end of the rod portion 66. The connection portion between the rod portion 66 and the piston portion 62 may be, for example, a female thread on one side and a male thread on the other side, and integrated by screwing, or the two may be integrated using a fixing device such as a screw. Also, instead of fixing and integrating the piston portion 62 and the rod portion 66 as in this embodiment, the piston portion 62 and the tip portion of the rod portion 66 may be connected by contacting them. Also, the tip portion 66a of the rod portion 66 may be detachable from the shaft portion 66b of the rod portion 66. If multiple types of tip portions 66a with different lengths are prepared, the length of the rod portion 66 can be changed on the tip portion 66a side to adjust the stroke length of the piston portion 62.

A partition wall 70 is connected to the other end of the rod portion 66. The partition wall 70 is integrated with the rod portion 66. In this embodiment, the other end of the rod portion 66 is axial, but it may be adjustable in length, just like the tip portion 66a.

The casing 68 is a cylindrical member having a hollow internal space. One end of the casing 68 is closed. The other end of the casing 68 is connected to the non-communicating space 60 of the tank body 52a and is not connected to the external space. The casing 68 has a first casing connection port 68a and a second casing connection port 68b at one end and the other end in the axial direction.

The partition wall 70 separates the internal space of the casing 68 into a first space 70a on the first casing connection port 68a side and a second space 70b on the second casing connection port 68b side. The partition wall 70 is plate-shaped and is arranged so that its outer circumferential surface is in close contact with the inner circumferential surface of the casing 68 via a sealing member such as an O-ring. The other end side of the rod portion 66 (the side opposite to the connection end of the piston portion 62) is connected to the surface of the partition wall 70 on the second space 70b side. The partition wall 70, together with the rod portion 66, is capable of reciprocating in the axial direction of the casing 68 while maintaining a position in which the outer circumferential surface is in contact with the inner circumferential surface of the casing 68. The partition wall 70 can be reciprocated in the axial direction inside the casing 68 by introducing and discharging gas through the first casing connection port 68a and the second casing connection port 68b and changing the pressure balance between the first space 70a and the second space 70b.

The first casing connection port 68a is connected to an intake and exhaust device 72 via piping. The intake and exhaust device 72 can introduce and exhaust gas (air in this embodiment) to and from the casing 68, and can also stop the introduction and exhaust of gas between the casing 68 and the intake and exhaust device 72. The intake and exhaust device 72 includes a solenoid valve 72b, a pilot check valve 72c, and a first speed controller 72d, which are arranged in order from the gas supply source 72a toward the casing 68, along a first piping system 74 that connects the gas supply source 72a and the first casing connection port 68a of the casing 68.

The supply source 72a is capable of pumping gas toward the casing 68. The supply source 72a can be, for example, a pump or a compressor. The solenoid valve 72b switches the passage of the gas supplied by the supply source 72a in the first piping system 74. The solenoid valve 72b may be of any suitable switching type, such as a three-position closed center type or a three-position pressure center type, but in this embodiment, a three-position exhaust center switching type is used. If a three-position exhaust center type is used as the solenoid valve 72b as in this embodiment, sufficient responsiveness can be ensured even if the solenoid valve 72b and the casing 68 are far apart.

The supply source 72a is connected to the supply port PI of the solenoid valve 72b. The two output ports A and B of the solenoid valve 72b are connected to the pilot check valve 72c by piping. The solenoid valve 72b is also provided with two exhaust ports EA and EB that are open to the atmosphere. The solenoid valve 72b can be switched to three states, a first state, a second state, and a third state, by changing the valve position. Specifically, as shown in FIG. 3, the first state is a state in which the supply port PI and the output port B are connected, and the exhaust port EA and the output port A are connected. As shown in FIG. 4, the second state is a state in which the supply port PI and the output port A are connected, and the exhaust port EB and the output port B are connected. As shown in FIG. 5, the third state is a state in which the output ports A and B are connected to the exhaust ports EA and EB, respectively.

The pilot check valve 72c has three connection ports PA, PB, and PC. The connection ports PA and PB of the pilot check valve 72c are connected by piping to the output ports A and B provided on the solenoid valve 72b, respectively. In addition, the pilot check valve 72c has a pipe connected to the first casing connection port 68a connected to the connection port PC. When no pressure is applied to the connection port PA, the pilot check valve 72c allows gas to flow from the connection port PB to the connection port PC, and functions as a check valve that blocks the reverse flow from the connection port PC to the connection port PB. In addition, when a pressure of a predetermined value or more is applied to the connection port PA, the pilot check valve 72c is released from its function as a check valve, and the flow from the connection port PC to the connection port PB is permitted.

The pilot check valve 72c is connected to the solenoid valve 72b via the first piping system 74 as described above. Therefore, when the solenoid valve 72b is in the first state, and pressure is not applied to the connection port PA of the pilot check valve 72c, but pressure is applied to the connection port PB, gas can be flowed from the connection port PB to the connection port PC, and gas can be introduced into the casing 68 from the first casing connection port 68a. When the solenoid valve 72b is in the second state, pressure of a predetermined value or more is applied to the connection port PA, and the pilot check valve 72c does not function as a check valve. In addition, the connection port PA is opened to the atmosphere via the exhaust port EB of the solenoid valve 72b. Therefore, when the solenoid valve 72b is in the second state, gas can be discharged from the first casing connection port 68a of the casing 68. Furthermore, when the solenoid valve 72b is in the third state, no pressure acts on either of the connection ports PA or PB, and the pilot check valve 72c functions as a check valve. Therefore, when the solenoid valve 72b is in the third state, it is possible to prevent gas from entering or leaving the casing 68.

The first speed controller 72d is provided in the pipeline connecting the above-mentioned pilot check valve 72c and the first casing connection port 68a of the casing 68. The first speed controller 72d is equipped with a residual pressure exhaust valve. The first speed controller 72d is also capable of meter-out control.

On the other hand, a second piping system 80 is connected to the second casing connection port 68b of the casing 68. The second piping system 80 is provided with a silencer 82 and a second speed controller 84. The second piping system 80 is open to the atmosphere via the silencer 82. As a result, the second piping system 80 is configured to allow gas (air in this embodiment) to flow in and out in the area on the second casing connection port 68b side of the casing 68. In addition, the second speed controller 84 is capable of meter-out control.

The buffer tank 50 can achieve three states, a pressurized state, a depressurized state, and a holding state, by utilizing the above-mentioned configuration. Each of these states can be achieved by controlling the movement of the piston portion 62 inside the tank portion 52 using the drive portion 64 that constitutes the volume fluctuation mechanism 54.

Specifically, the pressurized state is a state in which a pressurizing force is applied to the fluid. The pressurized state can be realized by reducing the volume of the communication space 58 in the tank section 52 that communicates with the supply path 40 by the volume fluctuation mechanism 54. To explain in more detail, when the buffer tank 50 is pressurized, as shown in FIG. 3, the solenoid valve 72b constituting the drive section 64 is set in the first state, and gas is supplied to the solenoid valve 72b by the supply source 72a. As a result, no pressure acts on the connection port PA of the pilot check valve 72c, and pressure acts on the connection port PB, and gas flows from the connection port PB to the connection port PC, and gas is introduced into the first space 70a from the first casing connection port 68a provided in the casing 68 of the drive section 64. Accordingly, the partition wall 70 moves in a direction in which the first space 70a expands inside the casing 68. This increases the pressure acting on the non-communicating space 60 side of the piston portion 62, which is connected to the partition wall 70 via the rod portion 66. As a result, the piston portion 62 moves in a direction that reduces the volume of the communicating space 58. In this way, the buffer tank 50 is in a pressurized state that exerts a pressurizing force on the fluid.

The reduced pressure state is a state in which a reduced pressure force is exerted on the fluid. The reduced pressure state can be achieved by increasing the volume of the communication space 58 in the tank section 52 that communicates with the supply path 40 by the volume fluctuation mechanism 54. To explain in more detail, when the buffer tank 50 is reduced pressure, as shown in FIG. 4, the solenoid valve 72b constituting the drive section 64 is set to the second state, and gas is supplied to the solenoid valve 72b by the supply source 72a. As a result, a pressure of a predetermined value or more acts on the connection port PA of the pilot check valve 72c, and the pilot check valve 72c does not function as a check valve. In addition, the connection port PA is opened to the atmosphere through the exhaust port EB of the solenoid valve 72b. Therefore, when the solenoid valve 72b is set to the second state, gas is discharged from the first casing connection port 68a of the casing 68. Accordingly, inside the casing 68, the partition wall 70 moves in a direction in which the second space 70b increases. As a result, the pressure acting on the non-communicating space 60 side of the piston portion 62, which is connected to the partition wall 70 via the rod portion 66, decreases. This causes the piston portion 62 to move in a direction that increases the volume of the communicating space 58. In this way, the buffer tank 50 is in a reduced pressure state in which a decompression force acts on the fluid.

The holding state is a state in which neither pressurizing nor depressurizing force is applied to the fluid. The holding state can be achieved by stopping the increase or decrease in the volume of the communication space 58 by the volume change mechanism 54. To explain in more detail, when the buffer tank 50 is put into the holding state, as shown in FIG. 5, the solenoid valve 72b constituting the drive unit 64 is put into the third state. As a result, no pressure acts on either of the connection ports PA and PB provided in the pilot check valve 72c, and the pilot check valve 72c functions as a check valve. Therefore, when the solenoid valve 72b is put into the third state, it is possible to put the casing 68 into a state in which gas does not enter or leave. Therefore, inside the casing 68, the partition wall 70 is put into a stopped state. Accordingly, the pressure fluctuation acting on the piston portion 62 connected to the partition wall 70 via the rod portion 66 and the volume fluctuation of the communication space 58 are not generated. In this way, the buffer tank 50 is put into a holding state in which neither pressurizing nor depressurizing force is applied to the fluid.

As shown in FIG. 1, a remaining amount grasping unit 90 is provided downstream of the above-mentioned buffer tank 50 in the flow direction of the fluid toward the discharge device 30. The remaining amount grasping unit 90 is for grasping the remaining amount of fluid in the discharge device 30. The remaining amount grasping unit 90 may grasp the remaining amount of fluid in the discharge device 30 by directly measuring it, for example, or may grasp the remaining amount of fluid in the discharge device 30 indirectly from the supply state of fluid to the discharge device 30 or the discharge state of fluid in the discharge device 30. Specifically, the remaining amount grasping unit 90 may grasp the remaining amount of fluid in the discharge device 30 indirectly from a measurement value related to the supply state of fluid, such as the supply pressure of fluid to the discharge device 30 or the flow rate of fluid to the discharge device 30.

The remaining amount grasping unit 90 may be, for example, a unit in which a sensor 92 for measuring the supply pressure and flow rate of the fluid and a processing unit 94 for performing processing to grasp the remaining amount of the fluid in the discharge device 30 based on the measurement value by the sensor 92 are integrally provided, or the sensor 92 and the processing unit 94 are separately provided. In this embodiment, a pressure sensor for detecting the supply pressure of the fluid to the discharge device 30 (hereinafter also referred to as "supply pressure P") is adopted as the sensor 92. In addition, the function of the processing unit 94 is assigned to the control device 200 described later. Therefore, by inputting the measurement value of the sensor 92 to the control device 200, the control device 200 can grasp the remaining amount of the fluid in the discharge device 30. In this embodiment, the control device 200 grasps that the remaining amount of the fluid in the discharge device 30 is within the appropriate range, provided that the supply pressure P detected by the sensor 92 is within the range of the upper limit value (hereinafter also referred to as "upper limit pressure PH") and the lower limit value (hereinafter "lower limit pressure PL") of a predetermined pressure range (PL < P < PH).

The control device 200 is for controlling the operation of the fluid discharge system 10. In addition to functioning as the processing unit 94 of the remaining amount grasping unit 90 described above, the control device 200 also controls the operation of the pump 20, discharge device 30, buffer tank 50, etc.

<<Operation of the fluid discharge system 10>>
The fluid discharge system 10 can be operated in four operation modes under the control of the control device 200. Specifically, the fluid discharge system 10 can be operated in four operation modes consisting of (1) pump supply mode, (2) tank accumulation mode, (3) tank supply mode, and (4) combined supply mode. In addition, the fluid discharge system 10 can stably discharge the fluid in the discharge device 30 by sequentially operating in the four operation modes. Hereinafter, the operation of the fluid discharge system 10 will be described, first in terms of the operation in the four operation modes. In addition, after describing the operation in each operation mode, the operation of the fluid discharge system 10 realized by sequentially operating in each operation mode will be described.

(1) Pump supply mode The pump supply mode is an operation mode in which the fluid is supplied from the pump 20 to the discharge device 30 while the buffer tank 50 is in a holding state. As shown in Fig. 6, in the pump supply mode, the control device 200 opens the valve 48 provided in the supply path 40 between the buffer tank 50 and the pump 20. The control device 200 also controls the operation of the pump 20 to operate or stop depending on the remaining amount of the fluid in the discharge device 30 grasped by the remaining amount grasping unit 90.

In this embodiment, the control device 200 grasps the remaining amount of fluid in the discharge device 30 using the supply pressure P to the discharge device 30 detected by the sensor 92 as an index, and controls the operation of the pump 20 according to the supply pressure P. Specifically, as shown in the timing chart of FIG. 7, the control device 200 stops the operation of the pump 20 on the condition that the supply pressure P is equal to or higher than a predetermined upper limit pressure PH, since it is not necessary to supply fluid to the discharge device 30. On the other hand, on the condition that the supply pressure P is equal to or lower than a predetermined lower limit pressure PL, the control device 200 operates the pump 20 on the condition that the remaining amount of fluid in the discharge device 30 is below an appropriate value. The operation of the fluid discharge system 10 in the pump supply mode is as shown in the flowchart of FIG. 8. The operation of the fluid discharge system 10 in the pump supply mode will be described in more detail below with reference to the flowchart of FIG. 8.

(Step 1-1)
In step 1-1, the control device 200 opens the valve 48. If the valve 48 is already open, the control device 200 maintains the valve 48 in the open state. After that, the control device 200 advances the control flow to step 1-2.

(Step 1-2)
In step 1-2, the control device 200 checks whether the remaining amount of fluid in the storage section 22 of the pump 20 has decreased to the lower limit of the storage section 22. If the remaining amount of fluid in the storage section 22 is at the lower limit, the control flow ends because the fluid cannot be pumped even if the pump 20 is operated. On the other hand, if there is fluid in the storage section 22 that exceeds the lower limit, the control device 200 advances the control flow to step 1-3.

(Step 1-3)
In step 1-3, the control device 200 checks whether the supply pressure P detected by the sensor 92 constituting the remaining amount grasping unit 90 is equal to or lower than the lower limit pressure PL. Here, when the supply pressure P is higher than the lower limit pressure PL, there is no need to operate the pump 20 to supply the fluid to the discharge device 30. Therefore, when the supply pressure P is higher than the lower limit pressure PL, the control device 200 waits in step 1-3. On the other hand, when the supply pressure P is equal to or lower than the lower limit pressure PL, it is necessary to supply the fluid to the discharge device 30. Therefore, in this case, the control device 200 advances the control flow to step 1-4.

(Step 1-4)
In step 1-4, the control device 200 operates the pump 20. As a result, the fluid stored in the storage section 22 is pumped by the pump 20 toward the discharge device 30. Thereafter, the control device 200 advances the control flow to step 1-5.

(Step 1-5)
In step 1-5, the control device 200 checks whether the remaining amount of fluid in the storage section 22 of the pump 20 has reached a lower limit. If the remaining amount of fluid in the storage section 22 has reached the lower limit, the control device 200 advances the control flow to step 1-6. On the other hand, if the remaining amount of fluid has not reached the lower limit, the control device 200 advances the control flow to step 1-7.

(Step 1-6)
In step 1-5 described above, if the remaining amount of the fluid in the reservoir 22 has reached the lower limit, further operation of the pump 20 will not allow the fluid to be supplied to the discharge device 30. Therefore, in step 1-6, the control device 200 ends the series of control flows.

(Step 1-7)
In step 1-7, the control device 200 checks whether the supply pressure P is equal to or higher than the upper limit pressure PH. If the supply pressure P has not reached the upper limit pressure PH, the control device 200 returns the control flow to step 1-5 to continue supplying the fluid to the discharge device 30. On the other hand, if the supply pressure P is equal to or higher than the upper limit pressure PH, the control device 200 advances the control flow to step 1-8.

(Step 1-8)
In step 1-8, the control device 200 stops the pump 20. This stops the supply of fluid from the pump 20 to the discharge device 30. Thereafter, the control device 200 advances the control flow to step 1-9.

(Step 1-9)
In step 1-9, the control device 200 checks the remaining amount of fluid in the storage section 22 of the pump 20. If the remaining amount of fluid has not reached the lower limit of the storage section 22, the control device 200 returns the control flow to step 1-3. On the other hand, if the remaining amount of fluid has reached the lower limit of the storage section 22, the pump 20 cannot supply any more fluid to the discharge device 30, and therefore the control flow is terminated.

(2) Tank Accumulation Mode Next, the tank accumulation mode will be described in detail. The tank accumulation mode is an operation mode in which the fluid is accumulated (charged) in the buffer tank 50 in preparation for the tank supply mode, which will be described later in detail, while continuing to supply the fluid from the pump 20. The tank accumulation mode is an operation mode in which the fluid is accumulated inside the buffer tank 50 (communication space 58) by sucking the fluid into the buffer tank 50. In the tank accumulation mode, the operation of the buffer tank 50 during accumulation is controlled based on the measurement value of the remaining amount grasping unit 90. In addition, the tank accumulation mode is an operation mode in which the discharge device 30 can continue to discharge the fluid even during accumulation of the fluid in the buffer tank.

As shown in FIG. 9, when operating in tank accumulation mode, the control device 200 opens the valve 48 provided in the supply path 40, enabling the pump 20 to supply fluid to the buffer tank 50. The control device 200 also controls the operation of the pump 20 to operate and stop depending on the remaining amount of fluid in the discharge device 30 as determined by the remaining amount determination unit 90.

In addition, in the tank accumulation mode, the control device 200 controls the operation of the pump 20 and the buffer tank 50 based on the measurement value of the remaining amount grasping unit 90, as shown in the operation explanatory diagram of FIG. 9 and the timing chart of FIG. 10. The control device 200 grasps the remaining amount of fluid in the discharge device 30 using the supply pressure P to the discharge device 30 as an index, and controls the operation of the pump 20 and the buffer tank 50 according to the supply pressure P. Specifically, when the supply pressure P is higher than a predetermined upper limit pressure PH (first upper limit value), a sufficient amount of fluid is stored in the discharge device 30, so the buffer tank 50 is depressurized and the fluid is accumulated in the communication space 58 of the tank section 52. More specifically, as shown in FIG. 9(a), the control device 200 opens the valve 48 to stop the pump 20 and depressurizes the buffer tank 50. As a result, the fluid is accumulated in the buffer tank 50. The operating conditions, such as the timing and duration for which the buffer tank 50 is put into a reduced pressure state, should be specified taking into account undershoot of the supply pressure P, for example by limiting it to a specified time after the supply pressure P reaches the upper limit pressure PH.

On the other hand, when the supply pressure P is lower than the predetermined lower limit pressure PL (first lower limit), the remaining amount of fluid in the discharge device 30 is below the appropriate value, so the buffer tank 50 is put into a holding state and accumulation of fluid in the communication space 58 is stopped. More specifically, as shown in FIG. 9(b), the control device 200 operates the pump 20 with the valve 48 in an open state, and puts the buffer tank 50 into a holding state. In this way, the control device 200 supplies the fluid pumped by the pump 20 to the discharge device 30.

By performing this type of control in the tank accumulation mode, the control device 200 accumulates the fluid in the buffer tank 50 when the supply pressure P is sufficiently high (when there is a sufficient amount of fluid remaining in the discharge device 30). That is, in the fluid discharge system 10, the control device 200 controls the operation in the tank accumulation mode by taking advantage of the fact that the buffer tank 50 can achieve a holding state. The operation of the fluid discharge system 10 in the tank accumulation mode is as shown in the flowchart of FIG. 11. The operation of the fluid discharge system 10 in the tank accumulation mode will be described in more detail below with reference to the flowchart of FIG. 11.

(Step 2-1)
In step 2-1, the control device 200 opens the valve 48. If the valve 48 is already open, the control device 200 maintains the valve 48 in the open state. This enables the pump 20 to pump fluid to the buffer tank 50 and the discharge device 30. The control device 200 then advances the control flow to step 2-2.

(Step 2-2)
In step 2-2, the control device 200 checks whether the remaining amount of fluid in the storage section 22 of the pump 20 has decreased to the lower limit of the storage section 22. If the remaining amount of fluid in the storage section 22 is at the lower limit, the control flow in Fig. 11 is terminated. On the other hand, if there is fluid in the storage section 22 that exceeds the lower limit, the control device 200 advances the control flow to step 2-3.

(Step 2-3)
In step 2-3, the control device 200 checks whether the supply pressure P detected by the sensor 92 constituting the remaining amount grasping unit 90 is equal to or lower than the lower limit pressure PL. Here, when the supply pressure P is higher than the lower limit pressure PL, there is no need to operate the pump 20 to supply the fluid to the discharge device 30, and therefore the pump is placed in a standby state in step 2-3. On the other hand, when the supply pressure P is equal to or lower than the lower limit pressure PL, it is necessary to supply the fluid to the discharge device 30. In this case, the control device 200 advances the control flow to step 2-4.

(Step 2-4)
In step 2-4, the control device 200 operates the pump 20. As a result, the fluid stored in the storage section 22 is pumped by the pump 20 toward the discharge device 30. Thereafter, the control device 200 advances the control flow to step 2-5.

(Step 2-5)
In step 2-5, the control device 200 checks whether the remaining amount of the fluid in the storage section 22 of the pump 20 has reached a lower limit. If the remaining amount of the fluid in the storage section 22 has reached the lower limit, the control device 200 advances the control flow to step 2-6. On the other hand, if the remaining amount of the fluid has not reached the lower limit, the control device 200 advances the control flow to step 2-7.

(Step 2-6)
When the control flow has moved to step 2-6, there is an insufficient amount of fluid remaining in the reservoir 22. Therefore, the control device 200 stops the pump 20. Then, the control flow ends.

(Step 2-7)
In step 2-7, the control device 200 checks whether the supply pressure P is equal to or lower than the upper limit pressure PH. If the supply pressure P is lower than the upper limit pressure PH, the control flow returns to step 2-5 and the operation of the pump 20 continues. On the other hand, if the supply pressure P is equal to or higher than the upper limit pressure PH, the control device 200 advances the control flow to step 2-8.

(Step 2-8)
In step 2-8, the control device 200 stops the pump 20. After that, the control device 200 advances the control flow to step 2-9.

(Step 2-9)
In step 2-9, the control device 200 puts the buffer tank 50 into a depressurized state. Specifically, the control device 200 controls the operation of the solenoid valve 72b constituting the volume fluctuation mechanism 54 of the buffer tank 50 so that it is in the second state. In addition, gas is supplied to the solenoid valve 72b by a supply source 72a consisting of an air compressor or the like. This causes the pilot check valve 72c to lose its function as a check valve, and gas is discharged from the first casing connection port 68a in the casing 68 of the volume fluctuation mechanism 54 through the connection port PA of the pilot check valve 72c and the exhaust port EB of the solenoid valve 72b. As a result, the partition wall 70 begins to move inside the casing 68, and the piston portion 62 moves in a direction in which the volume of the communication space 58 increases. In this way, the buffer tank 50 is in a depressurized state in which a depressurizing force acts on the fluid. When the communication space 58 of the buffer tank 50 is in a depressurized state, the fluid begins to flow from the supply path 40 into the communication space 58 and accumulates therein. When the buffer tank 50 is depressurized in step 2-9, the control device 200 advances the control flow to step 2-10.

(Step 2-10)
In step 2-10, the control device 200 manages the amount of accumulated fluid so that the amount of accumulated fluid is within a predetermined range after the start of accumulation of the fluid in the buffer tank 50 in step 2-9. The amount of accumulated fluid in the buffer tank 50 can be directly or indirectly derived and grasped by, for example, a method of directly measuring and deriving the amount of accumulated fluid using a residual amount sensor or a method of detecting and subtracting the amount of fluid flowing into and out of the buffer tank 50, or indirectly grasped by the time of flowing fluid into and out of the buffer tank 50. In this embodiment, the control device 200 manages the amount of accumulated fluid after the start of accumulation of the fluid in the buffer tank 50 in step 2-9 based on the time elapsed since the buffer tank 50 was depressurized in step 2-9. In step 2-10, the control device 200 checks whether the elapsed time Tx after the start of accumulation of the fluid in the buffer tank 50 in step 2-9 is equal to or greater than a predetermined time T2. The elapsed time T can be measured, for example, by a timer provided in the control device 200. Here, when it is confirmed that the elapsed time T is equal to or greater than the predetermined time T2, the control device 200 advances the control flow to step 2-11.

(Step 2-11)
In step 2-11, the control device 200 switches the buffer tank 50 to a holding state, and puts the fluid into a state in which neither pressurizing nor depressurizing force is applied. Specifically, the control device 200 puts the solenoid valve 72b provided in the drive unit 64 of the buffer tank 50 into a third state. As a result, no pressure acts on either of the connection ports PA and PB provided in the pilot check valve 72c, and the pilot check valve 72c functions as a check valve, and the inflow and outflow of gas in the casing 68 of the drive unit 64 is stopped. As a result, the partition wall 70 arranged inside the casing 68 stops, and the piston unit 62 connected to the partition wall 70 stops in the tank unit 52. In this way, the control device 200 puts the buffer tank 50 into a holding state. After that, the control device 200 advances the control flow to step 2-12.

(Step 2-12)
In step 2-12, the control device 200 checks whether the amount of fluid stored in the buffer tank 50 has reached its upper limit. The amount of fluid stored in the buffer tank 50 may be determined based on the output value from a remaining amount sensor provided in the buffer tank 50 or a position sensor capable of detecting the position of the partition wall 70, or the amount of fluid flowing into and out of the buffer tank 50 may be detected or derived, and the amount of fluid flowing into and out of the buffer tank 50 may be determined based on the amount of fluid flowing into and out of the buffer tank 50. In step 2-12, if it is determined that the amount of fluid stored in the buffer tank 50 has not reached its upper limit, the control device 200 returns the control flow to step 2-2 to further accumulate the fluid. On the other hand, if it is determined that the amount of fluid stored in the buffer tank 50 has reached its upper limit, the control device 200 completes a series of control flows.

(3) Tank supply mode Next, the tank supply mode will be described in detail. The tank supply mode is an operation mode in which fluid is supplied from the buffer tank 50 to the discharge device 30 while the pump 20 is stopped. The operation in the tank supply mode is an operation mode for discharging the fluid from the buffer tank 50 to the supply path 40 when the pump 20 is stopped, for example, to replace the storage section 22 in the pump 20 or to replenish the storage section 22 with fluid, thereby enabling the supply of the fluid to the discharge device 30 to be continued.

In the tank supply mode, as shown in the operation explanatory diagram of FIG. 12 and the timing chart of FIG. 13, the operation of the pump 20 and the buffer tank 50 is controlled based on the measurement value of the remaining amount grasping unit 90. Specifically, in the tank supply mode, when supplying the fluid to the discharge device 30, the operation control is performed so that the buffer tank 50 discharges the fluid on the condition that the measurement value of the remaining amount grasping unit 90 falls below a predetermined lower limit value (second lower limit value). More specifically, on the condition that the supply pressure P detected by the sensor 92 falls below a predetermined lower limit pressure PL, the pump 20 is stopped and the buffer tank 50 is pressurized with the valve 48 closed. As a result, the fluid is supplied from the buffer tank 50 to the discharge device 30 in a state in which the pump 20 is not pumping the fluid. The lower limit pressure PL, which is the second lower limit value, is set to the same value (pressure) as the first lower limit value in the tank accumulation mode described above, but may be different values (pressures).

On the other hand, in the tank supply mode, the operation of the buffer tank 50 is controlled to stop discharging the fluid, provided that the measurement value of the remaining amount grasping unit 90 exceeds a predetermined upper limit value (second upper limit value). More specifically, in the tank supply mode, the pump 20 is stopped and the valve 48 is closed, providing that the supply pressure P detected by the sensor 92 exceeds a predetermined upper limit pressure PH, and the buffer tank 50 is in a holding state. This prevents the fluid from being excessively supplied to the discharge device 30, which is sufficiently filled with the fluid. The upper limit pressure PH, which is the second upper limit value, is set to the same value (pressure) as the first upper limit value in the tank accumulation mode described above, but may be different values (pressures).

In the tank supply mode, the above-mentioned operations are performed in accordance with the flowchart shown in FIG. 14. Below, the operation of the fluid discharge system 10 in the tank supply mode will be explained in more detail with reference to the flowchart in FIG. 14.

(Step 3-1)
In step 3-1, the control device 200 checks the fluid storage state in the buffer tank 50. As a result, if the amount of fluid stored in the buffer tank 50 is the lower limit, there is a concern that the buffer tank 50 will not be able to supply the fluid, so the control device 200 completes a series of control flows. Here, in this step and the following steps, "when the amount of fluid stored in the buffer tank 50 is the lower limit" may refer to a state in which the amount of fluid stored has decreased to a level in which the fluid cannot be supplied, but in this embodiment, the control device 200 specifies a stage slightly before the level in which the fluid cannot be supplied (a state in which a small amount of fluid remains) as a case in which the amount of fluid stored is the lower limit, and performs operation control. On the other hand, if the amount of fluid stored in the buffer tank 50 is greater than the lower limit, the control device 200 advances the control flow to step 3-2.

(Step 3-2)
In step 3-2, the control device 200 checks the remaining amount of fluid in the discharge device 30. Specifically, the control device 200 checks whether the supply pressure P detected by the sensor 92 of the remaining amount grasping unit 90 is equal to or lower than a predetermined lower limit pressure PL (second lower limit value). Here, if the supply pressure P is higher than the lower limit pressure PL, there is a sufficient amount of fluid remaining in the discharge device 30, and there is no need to replenish the discharge device 30 with fluid. Therefore, in this case, the control device 200 waits in step 3-2. On the other hand, if the supply pressure P is equal to or lower than the lower limit pressure PL, the remaining amount of fluid in the discharge device 30 is low. In this case, the control device 200 advances the control flow to step 3-3.

(Step 3-3)
In step 3-3, the control device 200 pressurizes the buffer tank 50. As a result, the control device 200 exerts a pressurizing force on the fluid in the buffer tank 50, and discharges the fluid from the buffer tank 50 toward the discharge device 30 through the supply path 40. Specifically, the control device 200 controls the volume fluctuation mechanism 54 provided in the buffer tank 50 to move the piston portion 62 in a direction in which the volume of the communication space 58 communicating with the supply path 40 decreases. More specifically, the control device 200 supplies gas to the solenoid valve 72b from the supply source 72a while setting the solenoid valve 72b provided in the drive unit 64 to the first state. As a result, gas pressure-fed from the supply source 72a, which is an air compressor or the like, is introduced from the solenoid valve 72b through the pilot check valve 72c to the first space 70a of the casing 68 through the first casing connection port 68a. Accordingly, the partition wall 70 and the piston portion 62 are actuated, and the piston portion 62 moves in a direction that reduces the volume of the communication space 58. In this manner, the control device 200 pressurizes the buffer tank 50. When the buffer tank 50 is in a pressurized state, the fluid stored in the communication space 58 is discharged toward the discharge device 30 via the supply path 40.

(Step 3-4)
In step 3-4, the control device 200 checks whether the remaining amount of fluid in the buffer tank 50 has decreased to the lower limit. If the remaining amount of fluid in the buffer tank 50 has decreased to the lower limit, the control flow proceeds to step 3-5, and if the remaining amount of fluid has not reached the lower limit, the control flow proceeds to step 3-6.

(Step 3-5)
In step 3-5, the control device 200 stops discharging the fluid from the buffer tank 50. Specifically, the control device 200 places the buffer tank 50 in a holding state in the same manner as in step 2-11 described above. Thereafter, the control device 200 completes a series of control flows.

(Step 3-6)
In step 3-6, the control device 200 checks whether or not a sufficient amount of fluid has been filled into the discharge device 30. Specifically, the control device 200 checks whether or not the supply pressure P has reached a predetermined upper limit pressure PH (second upper limit value). If the supply pressure P is less than the upper limit pressure PH, the control device 200 returns the control flow to step 3-4. On the other hand, if the supply pressure P is equal to or greater than the upper limit pressure PH, the control device 200 advances the control flow to step 3-7.

(Step 3-7)
In step 3-7, the controller 200 sets the buffer tank 50 to the holding state in the same manner as in steps 2-11 and 3-5 described above. After that, the controller 200 advances the control flow to step 3-8.

(Step 3-8)
In step 3-8, the control device 200 checks the fluid storage state in the buffer tank 50. As a result, if the amount of fluid stored in the buffer tank 50 is greater than the lower limit, the control device 200 returns the control flow to step 3-2. On the other hand, if the amount of fluid stored in the buffer tank 50 is equal to the lower limit, operation in the tank supply mode cannot be continued any further, and the series of control flows is completed.

(4) Composite supply mode Next, the composite supply mode will be described in detail. The composite supply mode is an operation mode in which fluid is supplied to the discharge device 30 from both the pump 20 and the buffer tank 50. The operation in the composite supply mode is an operation mode performed for the purpose of supplementing the supply of fluid from the buffer tank 50 to the discharge device 30 with the supply of fluid from the pump 20 when it is assumed that the remaining amount of fluid in the tank section 52 is low, for example, at the end of the above-mentioned tank supply mode. If the operation in the composite supply mode is performed when it is assumed that the remaining amount of fluid in the tank section 52 is low, it is possible to both stabilize the supply pressure of the fluid to the discharge device 30 and use up the fluid accumulated in the buffer tank 50.

That is, when the amount of fluid remaining in the buffer tank 50 decreases in the tank supply mode, the distance between the bottom surface of the tank body 52a and the piston 62 becomes narrower, and the pressure loss increases. This causes the flow rate of fluid discharged from the buffer tank 50 to the discharge device 30 to decrease. If the flow rate of fluid from the buffer tank 50 to the discharge device 30 falls below the amount of fluid discharged from the discharge device 30, a shortage of fluid supply occurs. Therefore, when the amount of fluid remaining in the buffer tank 50 falls below a certain amount, the operation mode is switched to the combined supply mode, and the pump 20 is operated in addition to the buffer tank 50 to supply fluid, thereby stabilizing the supply pressure of fluid to the discharge device 30 and using up the fluid accumulated in the buffer tank 50.

In the combined supply mode, as shown in the operation explanatory diagram of FIG. 15 and the timing chart of FIG. 16, the operation of the pump 20 and the buffer tank 50 is controlled based on the measurement value of the remaining amount grasping unit 90. Specifically, in the combined supply mode, when supplying the fluid to the discharge device 30, the operation is controlled so that both the pump 20 and the buffer tank 50 supply the fluid toward the discharge device 30 on the condition that the measurement value of the remaining amount grasping unit 90 falls below a predetermined lower limit value. More specifically, the control device 200 pressurizes the buffer tank 50 and operates the pump 20 with the valve 48 open on the condition that the supply pressure P detected by the sensor 92 falls below a predetermined lower limit pressure PL. As a result, the control device 200 supplies the fluid to the discharge device 30 from both the buffer tank 50 and the pump 20. When fluid is supplied by both the pump 20 and the buffer tank 50 in the combined supply mode, the timing at which the pump 20 and the buffer tank 50 start pumping the fluid can be differentiated to adjust whether the fluid in the pump 20 or the buffer tank 50 is used preferentially. In this embodiment, in order to prevent deterioration of the fluid accumulated in the buffer tank 50, the control device 200 performs control to delay the timing at which the pump 20 starts pumping the fluid relative to the timing at which the buffer tank 50 starts pumping the fluid, in order to satisfy the desire to use up the fluid in the buffer tank 50 reliably in each cycle.

On the other hand, in the combined supply mode, the pump 20 and the buffer tank 50 are controlled to stop discharging the fluid when the measurement value of the remaining amount grasping unit 90 exceeds a predetermined upper limit value. More specifically, in the combined supply mode, when the supply pressure P detected by the sensor 92 exceeds a predetermined upper limit pressure PH, the pump 20 is stopped and the buffer tank 50 is put into a holding state. This prevents the fluid from being excessively supplied to the discharge device 30 that is sufficiently filled with the fluid.

In the combined supply mode, the above-mentioned operations are performed in accordance with the flowchart shown in FIG. 17. Below, the operation of the fluid discharge system 10 in the combined supply mode will be explained in more detail with reference to the flowchart in FIG. 17.

(Step 4-1)
In step 4-1, timing is started by a timer provided in the control device 200. Thereafter, the control device 200 advances the control flow to step 4-2.

(Step 4-2)
In step 4-2, the control device 200 checks whether the time measured by the timer (hereinafter also referred to as timer time Ty) is equal to or greater than the predetermined time T1. Here, the predetermined time T1 is a time measured to determine when to end the composite supply mode. By using the predetermined time T1 as a judgment condition in step 4-2, instead of providing limit switches or the like at two locations, one just before the lower limit of the buffer tank 50 and the other at the lower limit, a configuration can be adopted in which a limit switch or the like is provided only just before the lower limit of the buffer tank 50. Specifically, when operation is continued after the timing at which the remaining amount of fluid is detected by a sensor provided just before the lower limit of the buffer tank 50, the predetermined time T1 is specified based on the time at which the buffer tank 50 is expected to become empty, thereby making it possible to end the composite supply mode at an appropriate timing. In this way, instead of providing limit switches at two locations, one just before the lower limit of the buffer tank 50 and the other at the lower limit, if the composite supply mode is terminated using the predetermined time T1 as an index after the fluid is detected just before the lower limit of the buffer tank 50, there is an advantage in that it is possible to suppress the occurrence of a problem such as the composite supply mode never ending even if the liquid hardens at the bottom of the buffer tank 50 and the piston does not go down completely. Here, if it is confirmed that the timer time Ty is equal to or greater than the predetermined time T1, the control device 200 completes the control flow. On the other hand, if the timer time Ty is less than the predetermined time T1, the control device 200 advances the control flow to step 4-3.

(Step 4-3)
In step 4-3, the control device 200 checks the supply pressure P to the discharge device 30. If the supply pressure P is higher than a predetermined lower limit pressure PL, the control flow returns to step 4-2. On the other hand, if the supply pressure P is equal to or lower than the lower limit pressure PL, the control device 200 advances the control flow to step 4-4.

(Step 4-4)
In step 4-4, the control device 200 pressurizes the buffer tank 50 in the same manner as in step 3-3 described above. This causes a pressurizing force to act on the fluid in the buffer tank 50, and the fluid is supplied from the buffer tank 50 to the discharge device 30. Thereafter, the control device 200 advances the control flow to step 4-5.

(Step 4-5)
In step 4-5, the control device 200 checks the time that has elapsed since the buffer tank 50 was pressurized in step 4-4 (hereinafter also referred to as "pressurization time Tp"). The predetermined time T3 corresponds to a delay time that delays the timing at which the pump 20 starts pumping the fluid relative to the timing at which the buffer tank 50 starts pumping the fluid in the combined supply mode. While the pressurization time Tp is less than the predetermined time T3, the control device 200 keeps the control flow on hold in step 4-5. When the pressurization time Tp becomes equal to or greater than the predetermined time T3, the control device 200 advances the control flow to step 4-6.

(Step 4-6)
In step 4-6, the control device 200 operates the pump 20 to supply the fluid to the discharge device 30. At this time, the supply of the fluid to the discharge device 30 by the buffer tank 50, which has already started in step 4-4, is also continuing. Therefore, by operating the pump 20 in step 4-6, the fluid is supplied to the discharge device 30 by both the buffer tank 50 and the pump 20. When the operation of the pump 20 is started, the control device 200 advances the control flow to step 4-7.

(Step 4-7)
In step 4-7, the control device 200 checks the timer time Ty that started to be measured in step 4-1. If the timer time Ty is equal to or greater than the predetermined time T1, the control device 200 advances the control flow to step 4-8. If the timer time Ty is less than the predetermined time T1, the control device 200 advances the control flow to step 4-9.

(Step 4-8)
In step 4-8, the control device 200 stops the pump 20 and sets the buffer tank 50 to the holding state. The control for setting the buffer tank 50 to the holding state is performed in the same manner as in step 2-11 described above. As a result, the supply of fluid to the discharge device 30 is stopped in both the pump 20 and the buffer tank 50. Thereafter, the control device 200 completes the control flow.

(Step 4-9)
In step 4-9, the control device 200 checks the supply pressure P to the discharge device 30. If the supply pressure P is less than the predetermined upper limit pressure PH, the control flow returns to step 4-7. On the other hand, if the supply pressure P is equal to or greater than the upper limit pressure PH, the control device 200 advances the control flow to step 4-10.

(Step 4-10)
In step 4-10, similarly to step 4-8, the controller 200 stops the pump 20 and sets the buffer tank 50 to the holding state. After that, the controller 200 advances the control flow to step 4-11.

(Step 4-11)
In step 4-11, the control device 200 checks the timer time Ty that was started in step 4-1. If the timer time Ty is equal to or greater than the predetermined time T1, the control device 200 ends the series of control flows. If the timer time Ty is less than the predetermined time T1, the control device 200 returns the control flow to step 4-3.

As described above, the fluid discharge system 10 can be operated in four operating modes: (1) pump supply mode, (2) tank accumulation mode, (3) tank supply mode, and (4) combined supply mode. Next, the overall operation of the fluid discharge system 10, which is realized by sequentially operating in these operating modes, will be described. The overall operation of the fluid discharge system 10 can be performed in either a first operating pattern in which the fluid is accumulated in the buffer tank 50 in the initial stage, or a second operating pattern in which the fluid is accumulated in the buffer tank 50 in the intermediate stage. Therefore, in the following explanation, the operation in the first operating pattern will be described first, and then the operation in the second operating pattern will be described.

[Overall operation of the fluid discharge system 10 according to the first operation pattern]
The first operation pattern is an operation pattern in which operation in each operation mode is repeated in the order of tank accumulation mode → pump supply mode → tank supply mode → composite supply mode. A mode switching condition for switching from operation in each operation mode to operation in the next operation mode is set for each operation mode. The control device 200 controls switching of the operation mode every time the mode switching condition is satisfied. When the fluid discharge system 10 operates in the first operation pattern, the control device 200 controls the operation of the fluid discharge system 10 in accordance with the flowchart shown in FIG. 18 and the timing chart shown in FIG. 19. The operation of the fluid discharge system 10 in the first operation pattern will be described in more detail below with reference to FIG. 18 and FIG. 19.

(Step 5-1)
In step 5-1, the control device 200 starts operation in the tank accumulation mode in accordance with the control flow of Fig. 11. Thereafter, the control device 200 advances the control flow to step 5-2.

(Step 5-2)
In step 5-2, the control device 200 checks the remaining amount of fluid stored in the buffer tank 50 in the fluid discharge system 10 operating in the tank storage mode. If it is determined that the amount of fluid stored in the buffer tank 50 has reached the upper limit, the control device 200 advances the control flow to step 5-3.

(Step 5-3)
In step 5-3, the control device 200 starts operation in the pump supply mode in accordance with the control flow of Fig. 8. Thereafter, the control device 200 advances the control flow to step 5-4.

(Step 5-4)
In step 5-4, the control device 200 checks the remaining amount of fluid in the reservoir 22 of the pump 20 in the fluid discharge system 10 operating in the pump supply mode. If it is confirmed that the remaining amount of fluid in the reservoir 22 has reached a lower limit, the control device 200 advances the control flow to step 5-5.

(Step 5-5)
In step 5-5, the control device 200 starts operation in the tank supply mode in accordance with the control flow of Fig. 14. Thereafter, the control device 200 advances the control flow to step 5-6.

(Step 5-6)
In step 5-6, the control device 200 checks the remaining amount of fluid in the buffer tank 50 in the fluid discharge system 10 operating in the tank supply mode. If it is confirmed that the remaining amount of fluid in the buffer tank 50 has reached its lower limit, the control device 200 advances the control flow to step 5-7. In this step, the state in which "the remaining amount of fluid in the buffer tank 50 has reached its lower limit" may be a state in which the amount of fluid stored has decreased to a level at which the fluid cannot be supplied, but in this embodiment, the control device 200 defines a stage slightly before the level at which the fluid cannot be supplied (a state in which a small amount of fluid remains) as a case in which the remaining amount of fluid is at the lower limit, and performs operation control.

(Step 5-7)
In step 5-7, the control device 200 starts the operation in the composite supply mode in accordance with the control flow of Fig. 17. Thereafter, the control device 200 advances the control flow to step 5-8.

(Step 5-8)
In step 5-8, the control device 200 checks the timer time Ty in the fluid discharge system 10 operating in the composite supply mode. If it is confirmed that the timer time Ty is equal to or greater than the predetermined time T1, the control device 200 returns the control flow to step 5-1.

When the fluid discharge system 10 operates in the first operating pattern, the operation is controlled by the control device 200 in accordance with the above-mentioned flow. As described above, the first operating pattern accumulates fluid in the buffer tank 50 in the initial stage (step 5-1). Therefore, when the fluid discharge system 10 is operated in the first operating pattern, the fluid accumulated in the buffer tank 50 can be supplied to the discharge device 30 not only when the fluid in the storage section 22 of the pump 20 runs out, but also in cases where the pump 20 is unable to supply fluid due to an abnormality in the pump 20, for example.

[Overall operation of the fluid discharge system 10 according to the second operation pattern]
Next, the overall operation of the fluid discharge system 10 according to the second operation pattern will be described. The second operation pattern is an operation pattern in which operation in each operation mode is repeated in the order of pump supply mode → tank accumulation mode → tank supply mode → composite supply mode. In the second operation pattern, a mode switching condition for switching from operation in each operation mode to operation in the next operation mode is also set for each operation mode. The control device 200 controls the operation mode switching each time the mode switching condition is satisfied. When the fluid discharge system 10 operates in the second operation pattern, the control device 200 controls the operation of the fluid discharge system 10 according to the flowchart shown in FIG. 20. Hereinafter, the operation of the fluid discharge system 10 according to the second operation pattern will be described in more detail with reference to FIG. 20.

(Step 6-1)
In step 6-1, the control device 200 starts operation in the pump supply mode in accordance with the control flow of Fig. 8. Thereafter, the control device 200 advances the control flow to step 6-2.

(Step 6-2)
In step 6-2, the control device 200 checks the remaining amount of fluid in the reservoir 22 of the pump 20 in the fluid discharge system 10 operating in the pump supply mode. If it is confirmed that the remaining amount of fluid in the reservoir 22 is about to reach the lower limit, the control device 200 advances the control flow to step 6-3.

(Step 6-3)
In step 6-3, the control device 200 starts operation in the tank accumulation mode in accordance with the control flow of Fig. 11. Thereafter, the control device 200 advances the control flow to step 6-4.

(Step 6-4)
In step 6-4, the control device 200 checks the remaining amount of fluid in the storage section 22 in the fluid discharge system 10 operating in the tank accumulation mode. If it is confirmed that the accumulated amount of fluid in the storage section 22 has reached the lower limit, the control device 200 advances the control flow to step 6-5.

(Step 6-5)
In step 6-5, the control device 200 starts operation in the tank supply mode in accordance with the control flow of Fig. 14. Thereafter, the control device 200 advances the control flow to step 6-6.

(Step 6-6)
In step 6-6, the control device 200 checks the remaining amount of fluid in the buffer tank 50 in the fluid discharge system 10 operating in the tank supply mode. Here, when it is confirmed that the remaining amount of fluid in the buffer tank 50 has reached the lower limit, the control device 200 advances the control flow to step 6-7. In this step, the state in which "the remaining amount of fluid in the buffer tank 50 has reached the lower limit" may be a state in which the storage amount has decreased to a level at which the fluid cannot be supplied, but in this embodiment, the control device 200 defines a stage slightly before the level at which the fluid cannot be supplied (a state in which a small amount of fluid remains) as a case in which the remaining amount of fluid is the lower limit, and performs operation control.

(Step 6-7)
In step 6-7, the control device 200 starts the operation in the composite supply mode in accordance with the control flow of Fig. 17. Thereafter, the control device 200 advances the control flow to step 6-8.

(Step 6-8)
In step 6-8, the control device 200 checks the timer time Ty in the fluid dispensing system 10 operating in the composite supply mode. If it is confirmed that the timer time Ty is equal to or greater than the predetermined time T1, the control device 200 returns the control flow to step 6-1.

When the fluid discharge system 10 operates in the second operating pattern, the control device 200 controls the operation in accordance with the above-mentioned flow. As described above, in the second operating pattern, prior to operation in the tank accumulation mode, operation in the pump supply mode is performed, and in the intermediate stage (step 6-3), fluid is accumulated in the buffer tank 50 in the tank accumulation mode. In this way, when the fluid discharge system 10 is operated in the second operating pattern, the fluid is accumulated in the buffer tank 50 at a stage before the remaining amount of fluid in the storage section 22 of the pump 20 reaches the lower limit, and the supply source of the fluid to the discharge device 30 is switched to the buffer tank 50. Therefore, according to the second operating pattern, the period during which the fluid is accumulated (remains) in the buffer tank 50 can be minimized.

As described above, the fluid discharge system 10 of this embodiment includes, in addition to the pump 20 and the discharge device 30, a buffer tank 50 disposed in the middle of the supply path 40 connecting the pump 20 and the discharge device 30. The fluid discharge system 10 is capable of realizing a pressure acting state in which the buffer tank 50 exerts pressure on the fluid. The fluid discharge system 10 is also capable of realizing a pressurized state in which a pressurizing force is exerted on the fluid and a depressurized state in which a depressurizing force is exerted on the fluid as the pressure acting state. Therefore, the fluid discharge system 10 of this embodiment can pressure-feed the fluid toward the discharge device 30 by exerting pressure on the fluid toward the outside of the buffer tank 50 in the pressurized state. Therefore, the fluid discharge system 10 can suppress pressure fluctuations caused by switching the supply source of fluid for the discharge device 30 from the pump 20 to the buffer tank 50.

In addition, the fluid discharge system 10 can smoothly draw the fluid into the buffer tank 50 by reducing the pressure in the buffer tank 50 and applying pressure to the fluid in a direction toward the inside of the buffer tank 50. This allows the fluid discharge system 10 to draw in and store the fluid in the buffer tank 50 in preparation for supplying the fluid from the buffer tank 50 to the discharge device 30. Therefore, the fluid discharge system 10 can utilize the fluid storage function in the buffer tank 50 to contribute to a stable supply of fluid to the discharge device 30.

In the fluid discharge system 10 of this embodiment, the buffer tank 50 can realize a holding state in which no pressure is applied to the fluid, in addition to the above-mentioned pressure acting state (pressurized state, depressurized state). Therefore, in a state in which the discharge device 30 can discharge the fluid without using the buffer tank 50, such as during operation in the pump supply mode or when the remaining amount of fluid in the discharge device 30 is sufficient, or in a state in which it is not appropriate to continue accumulating liquid in the buffer tank 50 considering the remaining amount of fluid in the discharge device 30 during operation in the tank accumulation mode, the supply pressure of the fluid to the discharge device 30 and the discharge pressure of the fluid in the discharge device 30 can be suppressed from fluctuating due to the influence of the buffer tank 50. Therefore, according to the fluid discharge system 10 of this embodiment, fluctuations in the supply pressure of the fluid to the discharge device 30 and fluctuations in the discharge pressure in the discharge device 30 due to pressure acting on the fluid from the buffer tank 50 can be suppressed.

The fluid discharge system 10 of this embodiment can stably supply fluid to the discharge device 30 by operating in each of the above-mentioned operating modes without providing multiple pumps 20. Therefore, the fluid discharge system 10 of this embodiment can suppress increases in installation space and costs compared to a configuration with multiple pumps 20.

In this embodiment, the pressure acting state exerting pressure on the fluid in the buffer tank 50 is an example of changing the pressure in three stages, consisting of a pressurized state in which a positive pressure acts on the fluid from the buffer tank 50 side toward the supply line 40 side, a reduced pressure state in which a negative pressure acts on the fluid from the buffer tank 50 side toward the supply line 40 side, and a holding state in which no pressure acts on the fluid, but the present invention is not limited to this. For example, in the pressurized state or reduced pressure state, the pressure acting state of the pressure acting on the fluid may be changed in multiple stages, or the pressure acting state may be changed steplessly.

Specifically, as described above, in the volume fluctuation mechanism 54, instead of providing a solenoid valve 72b, a pilot check valve 72c, and a first speed controller 72d in the first piping system 74 connected to the first casing connection port 68a of the casing 68, it is preferable to provide, for example, a regulator 72x as shown in FIG. 22. With this configuration, it is possible to change the pressure acting on the fluid in multiple steps or in a stepless manner in the pressurized state or the reduced pressure state. Also, with this configuration, for example, in the tank accumulation mode described above, instead of putting the buffer tank 50 in a reduced pressure state, it is possible to change the pressure acting on the fluid from a strong pressurized state to a weak pressurized state, thereby further optimizing the pressure control in the buffer tank 50 according to the operating state of the fluid discharge system 10.

In addition, in the above-mentioned fluid discharge system 10, the buffer tank 50 includes a tank section 52 and a volume fluctuation mechanism 54, and the volume fluctuation mechanism 54 controls the increase and decrease in the volume of the communication space 58, thereby enabling the buffer tank 50 to be in a pressurized state, a depressurized state, or a holding state. Therefore, the fluid discharge system 10 can control the operation of the buffer tank 50 by controlling the increase and decrease in the volume of the communication space 58.

As described above, the fluid discharge system 10 is configured such that the volume fluctuation mechanism 54 includes a piston portion 62 that separates the inside of the tank portion 52 into a communication space 58 and a non-communicating space 60 that is not connected to the supply path 40, and a drive portion 64 that moves the piston portion 62. The buffer tank 50 is configured to be able to realize a pressurized state, a depressurized state, and a holding state by controlling the movement of the piston portion 62 with the drive portion 64. Therefore, the fluid discharge system 10 can appropriately realize a pressurized state, a depressurized state, and a holding state by controlling the movement of the piston portion 62, and can stably supply the fluid to the discharge device 30. Note that in this embodiment, an example is shown in which the piston portion 62 is provided and pressure is applied to the fluid through the piston portion 62, but the present invention is not limited to this. For example, the volume fluctuation mechanism 54 may be configured to directly apply pressure to the fluid, and may be configured without the piston portion 62.

In this embodiment, the driving unit 64 is configured as a gas cylinder device (an air cylinder device in this embodiment) capable of generating a driving force by the inflow and outflow of gas (air), but the present invention is not limited to this. For example, the fluid discharge system 10 may be configured as a hydraulic cylinder device using oil as the fluid as the driving unit 64, capable of generating a driving force by hydraulic pressure, or a driving unit 64x that can generate a driving force mechanically or electrically by using a motor or the like (see FIG. 23).

The present invention is not limited to the above-mentioned embodiment and modified examples, and other embodiments may be made within the scope of the claims, based on the teachings and spirit of the invention. For example, the above-mentioned buffer tank 50 has a connection part 56 connected to the supply path 40 at one end of the tank part 52, and the fluid flows in and out of the tank main body part 52a through the connection part 56, but it is possible to make it into a buffer tank 150 as shown in FIG. 22 instead. The buffer tank 150 has a configuration substantially the same as the above-mentioned buffer tank 50, but differs in that the connection port 56c, which is the inlet of the fluid to the tank main body part 52a, is provided above the connection port 56b, which is the outlet of the fluid in the tank main body part 52a. With such a configuration, the retention time of the fluid can be minimized, and the accumulated fluid can be used up even more.

In addition, in the above-mentioned fluid discharge system 10, in the tank accumulation mode, as a measure to suppress the drop in the supply pressure P to the discharge device 30, the accumulation of fluid in the buffer tank 50 is set to a time limit, but the present invention is not limited to this. For example, the accumulation of fluid in the buffer tank 50 may be stopped on the condition that the supply pressure P to the discharge device 30 becomes equal to or lower than a predetermined value. In addition, in the tank accumulation mode, the fluid discharge system 10 may improve the fluid supply capacity of the pump 20 compared to when operating in other operating modes, or may advance the operation start time of the pump 20 from the timing exemplified in the above embodiment to suppress the drop in the supply pressure P. In addition, the amount of accumulated fluid in the buffer tank 50 can be directly or indirectly derived and grasped by, for example, a method of directly measuring and deriving using a remaining amount sensor, a method of detecting and subtracting the amount of fluid flowing into and out of the buffer tank 50, or the like, or indirectly by the time when the fluid flows in and out of the buffer tank 50.

In addition, in the above-mentioned fluid discharge system 10, in the combined supply mode, the supply of fluid from the buffer tank 50 is started, and then the pump 20 is operated a while later, thereby preferentially consuming the fluid in the buffer tank 50, but the present invention is not limited to this. In the combined supply mode, for example, the rotation speed of the pump 20 may be reduced to reduce the pumping capacity, or the pressure of the buffer tank 50 may be increased to provide a difference in the fluid supply capacity between the pump 20 and the buffer tank 50, thereby preferentially consuming the fluid in the buffer tank 50. Note that when the pumping capacity of the pump 20 is reduced as described above, the supply of fluid from the buffer tank 50 and the supply of fluid by the operation of the pump 20 may be started simultaneously.

Here, the above-mentioned fluid discharge system 10 can be configured such that a sensor such as a limit switch is installed only slightly before the lower limit of the buffer tank 50 (slightly before the remaining amount of fluid becomes zero), and when this sensor detects that the remaining amount of fluid in the buffer tank 50 is at the lower limit (corresponding to steps 5-6 and 6-6), the operation mode is switched to the composite supply mode (steps 5-7 and 6-7). In this case, the determination of switching from the composite supply mode to the next operation mode can be made by a timer (steps 5-8 and 6-8), so that the remaining amount of fluid in the buffer tank 50 has reached the lower limit. Also, instead of determining the switching from the composite supply mode to the next operation mode in this manner, a sensor can be separately provided at the lower limit position of the buffer tank 50, and the composite supply mode can be switched to the next operation mode on the condition that this sensor detects that the fluid has decreased to the lower limit position. In addition, the state where "the amount of fluid remaining in the buffer tank 50 is at its lower limit" may be a state where the amount of fluid stored has decreased to a level where the fluid cannot be supplied, but the present invention is not limited to this and can be appropriately defined within the scope of the present invention. Specifically, as explained in this embodiment, even if a state just before the level where the fluid cannot be supplied (a state where there is a small amount of fluid remaining) is defined as "the amount of fluid remaining in the buffer tank 50 is at its lower limit," it does not depart from the scope of the present invention.

The above-mentioned fluid discharge system 10 is provided with a sensor 92 capable of detecting pressure between the buffer tank 50 and the discharge device 30, and controls each device based on the supply pressure P to the discharge device 30, but the present invention is not limited to this. For example, the sensor 92 may be a flow sensor or the like, and may grasp the remaining amount of fluid in the discharge device 30 according to the flow rate of the fluid supplied to the discharge device 30. In addition, when a separate accumulator is provided in front of the discharge device 30, it is preferable to grasp the remaining amount of fluid in the discharge device 30 based on the piston position of this accumulator and control each device. In addition, the fluid discharge system 10 is not limited to the above-mentioned arrangement of the sensor 92. Specifically, the sensor 92 is not limited to the supply path 40 or the accumulator, but may be provided in the discharge device 30 itself (for example, the casing 100 or the stator 104 of the discharge device 30).

As described above, the fluid discharge system 10 may, for example, be provided with a remaining amount sensor in the buffer tank 50, or a position sensor capable of detecting the position of the partition wall 70, and determine the amount of fluid stored in the buffer tank 50 based on the output values from these sensors, or may be capable of detecting or deriving the amount of fluid flowing into and out of the buffer tank 50, and determine the amount of fluid stored in the buffer tank 50 based on the amount of fluid flowing in and out. In addition, the fluid discharge system 10 is not limited to a configuration in which sensors are provided at the upper and lower limit positions of the buffer tank 50 and the amount of fluid stored in multiple stages can be detected, but may also be configured to continuously detect the amount of fluid stored in the buffer tank 50.

Specifically, as a device capable of continuously detecting the amount of fluid stored in the buffer tank 50, for example, as shown in FIG. 24, a detection device 300 for continuously detecting the amount of fluid stored in the buffer tank 50 may be provided. The detection device 300 shown in FIG. 24 detects the amount of fluid remaining in the buffer tank 50 by continuously detecting the position of a member (piston portion 62 in the illustrated example) that moves according to the amount of fluid remaining, or a rod portion 66 or partition wall 70 that moves in conjunction with this. In the example shown in FIG. 24, the detection device 300 includes a sensor dog 302 and a magnetic position detection sensor 304.

The sensor dog 302 is formed to emit magnetism, for example by incorporating a magnet. The sensor dog 302 can be attached to an object whose position is to be detected. The sensor dog 302 is attached to a position variable member 306 whose position varies depending on the amount of fluid remaining in the buffer tank 50, such as the piston portion 62, rod portion 66, and partition wall 70 that constitute a cylinder in the buffer tank 50. In the example shown in FIG. 24, the rod portion 66 is selected as the position variable member 306, and the sensor dog 302 is attached to the rod portion 66.

The magnetic position detection sensor 304 is a sensor that can detect the position of the sensor dog 302 based on the magnetism emitted from the sensor dog 302. The magnetic position detection sensor 304 is attached to the buffer tank 50 so that the range in which the sensor dog 302 moves in response to an increase or decrease in the amount of fluid stored in the buffer tank 50 is the detection range. In this embodiment, the magnetic position detection sensor 304 is attached to the casing 68 of the buffer tank 50 over the entire range of movement in which the sensor dog 302 is expected to move in response to an increase or decrease in the amount of fluid. In this embodiment, since the sensor dog 302 moves in the axial direction of the buffer tank 50, the magnetic position detection sensor 304 is arranged to extend in the axial direction of the buffer tank 50.

If the fluid discharge system 10 uses a detection device 300, such as that shown in FIG. 24, that can sense the entire stroke of the cylinder in the buffer tank 50, it is possible to grasp the remaining amount of fluid in the buffer tank 50 by relating the relationship between the tank volume (remaining amount of fluid) of the buffer tank 50 and the stroke of the cylinder. In other words, the detection device 300 can continuously detect the amount of fluid stored in the buffer tank 50.

Also, by using the configuration shown in FIG. 24, the upper and lower limits of the amount of fluid stored in the buffer tank 50 can be set or changed as appropriate, thereby controlling the operation of the fluid discharge system 10. Specifically, when a detection device such as a limit switch or a sensor is provided at the positions that represent the upper and lower limits of the amount of fluid stored in the buffer tank 50 as in the above embodiment, in order to change the upper and lower limits of the amount of fluid stored, it is necessary to physically move the installation position of the detection device. However, by using the above-mentioned detection device 300, the upper and lower limit positions can be set at appropriate positions within the range in which the magnetic position detection sensor 304 can detect the sensor dog 302, or the positions that represent the upper and lower limits can be changed, thereby controlling the operation of the fluid discharge system 10.

In addition, in the detection device 300, it is preferable to be able to display the remaining amount of fluid in the buffer tank 50 on a user interface 310 such as the operation control panel of the fluid discharge system 10 or the monitor of the control device based on the position information of the sensor dog 302 detected by the magnetic position detection sensor 304.

Specifically, as shown in FIG. 25, a remaining amount display unit 312 is provided that shows the remaining amount of fluid in the buffer tank 50, and the remaining amount is displayed by an indicator or a numerical value (indicator in the illustrated example). By visualizing the remaining amount of fluid in the buffer tank 50 in this way, the timing for refilling the fluid in the storage unit 22 in which the pump 20 is located or replacing the fluid 22 becomes clear. For example, if the storage unit 22 is a pail, the timing for replacing an empty pail (storage unit 22) with a new pail (storage unit 22) becomes clear.

When providing a user interface 310 as shown in FIG. 25, it is advisable to provide a mode display unit 314 that displays, in addition to or instead of the remaining amount of fluid in the buffer tank 50, in such a way that it is possible to identify in which operating mode the fluid discharge system 10 is operating. In the mode display unit 314 illustrated in FIG. 25, the display indicating the current operating mode is displayed in the same color as the displays indicating the other operating modes, making it possible to identify in which operating mode the fluid discharge system 10 is operating. This makes it possible to intuitively know in which operating mode the fluid discharge system 10 is operating, and to clearly know the timing for replacing the storage unit 22 or refilling the storage unit 22 with fluid.

The timing for replacing the storage section 22 or refilling the storage section 22 with fluid can be specified as appropriate, but in the fluid discharge system 10 according to the above embodiment, it is preferable to perform this during operation in tank supply mode. Therefore, as shown in FIG. 25, if it is clearly shown on the mode display section 314 that the operating state of the fluid discharge system 10 has entered tank supply mode, the timing for replacing the storage section 22 or refilling the storage section 22 with fluid can be clearly understood.

In addition, when providing a user interface 310 as shown in FIG. 25, it is preferable to make it possible to accept operations on the display portion (remaining amount display portion 312 in the illustrated example) of the indicator displayed thereon, for example, so that operation commands can be output to each portion and operation settings can be made in accordance with the operation. For example, in the example of FIG. 25, it is preferable to make it possible to accept operations on the display portion of the indicator in the remaining amount display portion 312 so that the length of the indicator can be adjusted. This allows the operator to intuitively perform tasks such as outputting a warning and setting either or both of the upper and lower limits of the remaining amount of fluid in the buffer tank 50, which serve as an indicator of the operating conditions.

The present invention is not limited to the above-described embodiments and variations, and other embodiments may be possible within the scope of the claims, based on the teachings and spirit of the invention. The components of the above-described embodiments may be arbitrarily selected and combined. Any component of the embodiment may also be arbitrarily combined with any component described in the means for solving the invention or any component that embodies any component described in the means for solving the invention. We intend to obtain rights to these as well through amendments to this application or divisional applications, etc.

The present invention can be suitably used in all fluid discharge systems for pumping and discharging fluids.

10: Fluid discharge system 20: Pump 22: Storage section 30: Discharge device 40: Supply path 50: Buffer tank 52: Tank section 54: Volumetric fluctuation mechanism 58: Communicating space 60: Non-communicating space 62: Piston section (partition section)
64: Drive unit

Claims (8)

A discharge device that discharges a fluid;
a pump having a storage section and capable of supplying the fluid stored in the storage section to the discharge device by pumping the fluid;
a supply passage connecting the pump and the discharge device so that a fluid can pass between them;
A buffer tank disposed in the middle of the supply path and capable of suctioning and discharging the fluid;
a remaining amount grasping unit that grasps the remaining amount of the fluid in the discharge device,
When the supply of the fluid by the pump is limited, the buffer tank discharges the fluid accumulated therein, thereby allowing the supply of the fluid to the discharge device to be continued;
This fluid discharge system is characterized by the fact that , when supplying fluid from the buffer tank, when the remaining amount of fluid in the discharge device detected by the remaining amount detecting unit is at a lower limit, the buffer tank starts supplying fluid to the discharge device by discharging the fluid accumulated inside, and when the remaining amount of fluid is at an upper limit, the buffer tank stops discharging the fluid, thereby stopping the supply of fluid. The remaining amount grasping unit,
a pressure detection device provided between the buffer tank and the discharge device in the supply path or in the discharge device;
2. The fluid discharge system according to claim 1, wherein a remaining amount of the fluid in the discharge device is grasped based on a measurement value of the pressure detection device. When supplying a fluid to the discharge device,
the buffer tank discharges the fluid on condition that the remaining amount of the fluid in the discharge device grasped by the remaining amount grasping unit falls below a predetermined lower limit, and the buffer tank stops discharging the fluid on condition that the remaining amount of the fluid in the discharge device grasped by the remaining amount grasping unit exceeds a predetermined upper limit;
3. The fluid discharge system according to claim 1, further comprising: The buffer tank is capable of accumulating a fluid inside the buffer tank by sucking the fluid,
4. The fluid discharge system according to claim 1, wherein the discharge device continues to discharge the fluid while the fluid is being accumulated. When accumulating the fluid in the buffer tank,
the buffer tank sucks the fluid on condition that the remaining amount of the fluid in the discharge device grasped by the remaining amount grasping unit exceeds a predetermined upper limit value, and the buffer tank stops sucking the fluid on condition that the remaining amount of the fluid in the discharge device grasped by the remaining amount grasping unit falls below a predetermined lower limit value;
5. The fluid discharge system according to claim 4, further comprising: The buffer tank is capable of accumulating the fluid inside the buffer tank by sucking the fluid,
When the supply of the fluid by the pump is limited, the buffer tank discharges the fluid accumulated therein, thereby allowing the supply of the fluid to the discharge device to be continued;
The fluid discharge system according to claim 1 or 2, characterized in that the operation of the buffer tank, both for accumulating the fluid and for supplying the fluid, is controlled based on the remaining amount of fluid in the discharge device grasped by the remaining amount grasping unit. The buffer tank is
When accumulating the fluid, at least one of an operation of sucking the fluid on condition that the remaining amount of the fluid in the discharge device grasped by the remaining amount grasping unit exceeds a predetermined first upper limit value, and an operation of stopping the suction of the fluid on condition that the remaining amount of the fluid in the discharge device grasped by the remaining amount grasping unit falls below a predetermined first lower limit value,
The fluid discharge system of claim 6, characterized in that when supplying a fluid, at least one of the following operations is performed: discharging the fluid on condition that the remaining amount of fluid in the discharge device grasped by the remaining amount grasping unit falls below a predetermined second lower limit value, and stopping the discharge of the fluid on condition that the remaining amount of fluid in the discharge device grasped by the remaining amount grasping unit exceeds a predetermined second upper limit value. The buffer tank is
a position variable member whose position varies within a predetermined range according to the remaining amount of fluid;
A detection device for detecting the position of the position variable member,
A fluid discharge system as described in any one of claims 1 to 7, characterized in that the remaining amount of fluid in the buffer tank can be grasped based on the correlation between the capacity of the buffer tank and the position of the position variable member.

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