JP2007100652A - Fuel supply device - Google Patents

Abstract

An object of the present invention is to increase fuel pressure more than during normal operation only when starting an internal combustion engine.
A fuel supply device (2) supplies fuel from a fuel tank (3) to a delivery pipe (7) by a fuel pump (4) via a fuel supply pipe (5), and a storage provided in a part of the pipe (5) when the engine (1) is stopped. The fuel is held in the portion 13 in a pressurized state, and when the engine 1 is started, the fuel in the storage portion 13 is released and liquid fuel is injected and supplied from the delivery pipe 7 to the engine 1 through the injector 6. The fuel return pipe 8 for returning the fuel from the delivery pipe 7 to the fuel tank 3 is provided with a fuel cutoff valve 32 for blocking the fuel flow. This shut-off valve 32 has a fuel pressure regulating function. A pressure regulator 31 is arranged in series with the fuel cutoff valve 32 in the fuel return pipe 8. The fuel shut-off valve 32 is composed of an electromagnetic valve, and includes a valve body that opens when acting in the same direction as the fuel flow and closes by a spring when acting in the opposite direction to the fuel flow.
[Selection] Figure 5

Description

  The present invention relates to a fuel supply device that supplies fuel to an internal combustion engine, and more particularly, to a fuel supply device that includes a fuel reservoir in a fuel supply path from a fuel tank to a fuel supply site.

  Conventionally, as this type of fuel supply apparatus, apparatuses described in Patent Documents 1 to 4 below are known. For example, Patent Document 1 describes a liquefied gas fuel supply device that supplies liquefied gas fuel in a fuel tank in a liquid state to a fuel supply portion of an internal combustion engine via a fuel supply path using a fuel pump. Here, a delivery pipe for distributing fuel to a plurality of fuel injection valves is described as a “fuel supply part”. A fuel supply pipe is described as the “fuel supply path”. The fuel supply device stores liquefied gas fuel in a pressurized state in a storage part provided including a part or all of the fuel supply path to the fuel supply part during a stop period of the internal combustion engine. There is provided pressurized storage means for releasing the liquefied gas fuel at the storage site at the time of starting. Here, the “storage part” is between the upstream side fuel cutoff valve and the downstream side fuel cutoff valve provided on the fuel supply path. Each fuel cutoff valve corresponds to a “pressurized storage means”. Further, the fuel supply device includes a fuel return pipe that returns fuel from the fuel supply portion to the fuel tank, and includes one relief valve in the middle of the pipe.

JP 2003-83172 A Public Technical 2004-500805 JP 2003-239788 A JP 2003-328858 A

  However, in the fuel supply device described in Patent Document 1, when the internal combustion engine is started, the liquefied gas fuel at the fuel supply site is quickly increased to high pressure by opening the liquefied gas fuel at the storage site by the pressurized storage means. It is necessary to ensure a liquid state. However, by using the pressurized storage means, the liquefied gas fuel can be maintained at a high pressure, but the pressure can only be increased up to the pressure value adjusted by the relief valve of the fuel return pipe. Only a higher pressure than during normal operation could not be achieved.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a fuel supply device capable of increasing the fuel pressure only during the startup of the internal combustion engine as compared with the normal operation.

  In order to achieve the above object, according to the first aspect of the present invention, the fuel in the fuel tank is supplied to the fuel supply site by the fuel pump via the fuel supply path, and the fuel is supplied from the fuel supply path when the internal combustion engine is stopped. The fuel is held in a pressurized state in a storage part including all or part of the part, and when the internal combustion engine is started, the fuel in the storage part is released and liquid fuel is transferred from the fuel supply part to the internal combustion engine. In the fuel supply device to be supplied, the purpose is to provide a shut-off means for shutting off the fuel flow in the fuel return path for returning the fuel at the fuel supply site to the fuel tank.

  According to the configuration of the above invention, when the internal combustion engine is started, the flow of the fuel in the fuel return path is interrupted by the interrupting means, so that the fuel released from the storage part is supplied to the fuel supply part at once. The pressure rises early.

  In order to achieve the above object, according to a second aspect of the present invention, in the fuel supply apparatus according to the first aspect, the shut-off means has a fuel pressure regulating function, and a separate pressure regulating means is provided in the fuel return path. The purpose is to provide it.

  According to the configuration of the invention, in addition to the operation of the invention described in claim 1, when the internal combustion engine is started, the fuel pressure regulating function of the shut-off means and the fuel pressure regulating function by the separate pressure regulating means cooperate. Thus, the fuel pressure at the fuel supply site is adjusted to be relatively high. Further, after the internal combustion engine is started, by opening the shut-off valve, the fuel pressure at the fuel supply site is adjusted to be relatively low only by the fuel pressure regulating function by the separate pressure regulating means.

  In order to achieve the above object, according to a third aspect of the present invention, in the fuel supply apparatus according to the second aspect, the shut-off means opens in the same direction as the fuel flow, and reverses the fuel flow. It is intended to be an electromagnetic valve including a valve body that is closed by an urging member by acting in a direction.

  According to the configuration of the above invention, in addition to the operation of the invention according to claim 2, since the solenoid valve exhibits the fuel cutoff function and the fuel pressure regulation function, the pressure regulation means separate from the solenoid valve is connected in series. It becomes possible to arrange. Moreover, the fuel pressure regulation value can be easily changed by changing the setting of the biasing force of the biasing member.

  In order to achieve the above object, the invention according to claim 4 is the invention according to any one of claims 1 to 3, wherein when the fuel pressure in the storage portion becomes a predetermined value or more, the fuel in the storage portion is stored. It is intended that a relief means for relieving the fuel to the fuel tank is provided.

  According to the configuration of the above invention, in addition to the operation of the invention according to any one of the first to third aspects, the fuel pressure at the storage portion does not become too high due to the operation of the relief means.

  In order to achieve the above object, according to a fifth aspect of the present invention, in the invention according to any one of the first to fourth aspects, when the internal combustion engine is stopped, the fuel remaining in the fuel supply portion is passed through the fuel return path. The purpose is to return to the fuel tank.

  According to the configuration of the above invention, in addition to the action of the invention according to any one of claims 1 to 4, the fuel at the fuel supply site is returned to the fuel tank when the internal combustion engine is stopped. Reduce. Further, the fuel supply site is cooled by the vaporization of the fuel under reduced pressure at the fuel supply site.

  In order to achieve the above object, according to a sixth aspect of the present invention, in the first aspect of the present invention, when the internal combustion engine is stopped, the fuel remaining in the fuel supply portion is separated from the fuel tank. The purpose is to provide a fuel collecting means for collecting.

  According to the configuration of the invention, in addition to the action of the invention according to any one of claims 1 to 4, the fuel at the fuel supply site is collected by the collecting means when the internal combustion engine is stopped. Fuel pressure is reduced. Further, the fuel supply site is cooled by the vaporization of the fuel under reduced pressure at the fuel supply site. Further, during operation of the internal combustion engine, the fuel collected by the collection means can be separately supplied to the internal combustion engine as necessary.

  In order to achieve the above object, according to a seventh aspect of the present invention, in the invention according to any one of the first to sixth aspects, the blocking means is closed when the internal combustion engine is started, and is opened after the internal combustion engine is started. The purpose is to be in a state.

  According to the configuration of the above invention, in addition to the operation of the invention according to any one of claims 1 to 6, since the shut-off means is closed when the internal combustion engine is started, the fuel pressure at the fuel supply site is normally increased early. Higher than pressure. Further, after the internal combustion engine is started, the shut-off means is opened, so that excess fuel at the fuel supply site is returned to the fuel tank via the fuel return path.

  According to the first aspect of the present invention, the fuel pressure can be increased earlier than during normal operation only when the internal combustion engine is started.

  According to the second aspect of the invention, in addition to the effect of the first aspect of the invention, the fuel pressure can be variably adjusted in two stages during the normal operation of the internal combustion engine, and the configuration therefor is simplified. be able to.

  According to the invention described in claim 3, in addition to the effect of the invention described in claim 2, the fuel pressure adjustment function by the electromagnetic valve can be easily adapted according to the variation of the internal combustion engine.

  According to the invention described in claim 4, in addition to the effect of the invention described in any one of claims 1 to 3, it is possible to prevent fuel leakage due to high pressure in the fuel supply path when the internal combustion engine is stopped.

  According to the invention described in claim 5, in addition to the effect of the invention described in any one of claims 1 to 4, it is possible to prevent fuel leakage due to high pressure at the fuel supply site when the internal combustion engine is stopped. . Further, by cooling the fuel supply part, liquefaction of the fuel supplied to the fuel supply part at the start can be promoted.

  According to the invention described in claim 6, in addition to the effect of the invention described in any one of claims 1 to 4, it is possible to prevent fuel leakage due to high pressure at the fuel supply site when the internal combustion engine is stopped. . Further, by cooling the fuel supply part, liquefaction of the fuel supplied to the fuel supply part at the start can be promoted.

  According to the invention described in claim 7, in addition to the effect of the invention described in any one of claims 1 to 6, it is possible to increase the fuel pressure at an early stage only at the time of starting the internal combustion engine as compared with the normal operation after the start. it can.

[First Embodiment]
Hereinafter, a first embodiment of the fuel supply device according to the present invention will be described in detail with reference to the drawings. In this embodiment, the fuel supply device of the present invention will be described as being embodied in an LPG engine that uses liquefied petroleum gas (LPG) as fuel.

  FIG. 1 is a schematic configuration diagram showing a fuel supply device in this embodiment. An LPG engine system mounted on a vehicle includes an LPG engine 1 as an internal combustion engine, and a fuel supply device 2 for injecting and supplying LPG as fuel to the engine 1. The fuel supply device 2 includes a fuel tank 3 that stores LPG in a liquid phase state. The electric fuel pump 4 built in the fuel tank 3 sucks the liquid phase LPG stored in the tank 3 and discharges it to the fuel supply pipe 5 at a high pressure. In this embodiment, the fuel supply pipe 5 corresponds to the fuel supply path of the present invention.

  In this embodiment, the LPG engine 1 is of a four-cylinder reciprocating type, and a fuel injection valve (injector) 6 for high-pressure fuel that supplies LPG in a liquid phase is provided for each cylinder. . Each injector 6 is connected to a delivery pipe 7. A fuel supply pipe 5 is connected to the delivery pipe 7. In this embodiment, each injector 6 and delivery pipe 7 correspond to a fuel supply portion of the present invention.

  Here, the liquid phase LPG discharged from the fuel pump 4 is pressure-fed and supplied to each injector 6 through the fuel supply pipe 5 and the delivery pipe 7. The supplied LPG in the liquid phase state is injected into each intake port of the LPG engine 1 in a liquid phase state by the operation of each injector 6. Liquid phase LPG injected from each injector 6 forms a combustible air-fuel mixture with air taken in through an intake passage (not shown) and is sucked into each cylinder. A fuel return pipe 8 is connected to the delivery pipe 7. The remaining LPG in the liquid phase in the delivery pipe 7 is returned to the fuel tank 3 via the fuel return pipe 8 as return fuel. In this embodiment, the fuel return pipe 8 corresponds to the fuel return path of the present invention.

  In this embodiment, in the middle of the fuel supply pipe 5, a tank side fuel cutoff valve 11 is provided in the vicinity of the fuel tank 3, and a delivery side fuel cutoff valve 12 is provided in the vicinity of the delivery pipe 7. Each of these fuel cutoff valves 11 and 12 is composed of an electromagnetic valve. In this embodiment, the fuel supply pipe 5 between the two fuel cutoff valves 11 and 12 corresponds to the storage portion 13 of the present invention, and when the LPG engine 1 is stopped, the two fuel cutoff valves 11 and 12 are connected. By closing, LPG is kept in a pressurized state in the storage site 13, and when the LPG engine 1 is started and operated, the two fuel cutoff valves 11, 12 are opened to open the storage site 13, so that the liquid The LPG in the state is supplied to the LPG engine 1 from the delivery pipe 7 and each injector 6.

  In this embodiment, in the fuel return passage 8, a return fuel cutoff valve 14, an upstream pressure regulator 15, and a downstream pressure regulator 16 are provided in series from the vicinity of the delivery pipe 7. Further, a bypass pipe 17 is provided between the upstream side and the downstream side of the downstream pressure regulator 16, and a bypass fuel cutoff valve 18 is provided in the pipe 17. Each of these fuel shut-off valves 14 and 18 is composed of an electromagnetic valve. The four fuel cutoff valves 11, 12, 14, 18 described above have the same basic configuration. The return fuel cutoff valve 14 corresponds to the cutoff means of the present invention. Therefore, when the bypass fuel shut-off valve 18 is closed, the LPG fuel flowing through the fuel return pipe 8 passes through the downstream pressure regulator 16 without flowing through the bypass pipe 17, as indicated by an arrow in FIG. Flowing. When the bypass fuel cutoff valve 18 is opened, the LPG fuel is returned to the fuel tank 3 through the bypass pipe 17 without flowing through the downstream pressure regulator 16.

  In FIG. 2, each fuel cutoff valve 11, 12, 14, 18 is shown with sectional drawing. Each fuel shut-off valve 11, 12, 14, 18 includes a valve body 21, a fuel passage 22 formed inside the valve body 21, and a valve seat 23 provided corresponding to the outlet 22 a of the fuel passage 22. A valve body 24 provided so as to be capable of reciprocating toward the valve seat 23, a spring 25 as a biasing member that biases the valve body 24 in a direction in which the valve body 24 is pressed against the valve seat 23 (a valve closing direction), and a valve body And a coil 26 for moving 24 by magnetic force. FIG. 2 shows a closed state in which the valve body 24 is pressed against the valve seat 23 by the urging force of the spring 25. The fuel pumped by the fuel pump 4 flows in the same direction as the valve closing direction of the valve body 24 as shown by the arrow. Each fuel cutoff valve 11, 12, 14, 18 excites the coil 26 by energization to move the valve body 24 in a direction opposite to the fuel flow direction against the biasing force and fuel pressure of the spring 25. Thus, the valve body 24 is opened. In this embodiment, the fuel shut-off valves 11, 12, 14, 18 are connected to the pipes 5, 8 so that the flow direction of fuel (indicated by arrows) is the valve closing direction of the valve body 24 as shown in FIG. , 17.

  As shown in FIG. 1, in this embodiment, an electronic control unit (ECU) 20 is provided to control the fuel pump 4, each injector 6, each fuel cutoff valve 11, 12, 14, 18 and the like. The ECU 20 is connected to the fuel pump 4, each injector 6, and each fuel cutoff valve 11, 12, 14, 18. Various sensors (not shown) including an ignition switch and a rotation speed sensor are connected to the ECU 20. The ECU 20 executes various controls according to a predetermined control program.

  Next, the fuel supply control of this embodiment will be described. FIG. 4 is a flowchart showing the contents of the fuel supply control program. The ECU 20 periodically executes this routine.

  First, in step 100, the ECU 20 determines whether or not the LPG engine 1 is stopped. The ECU 20 makes this determination based on, for example, whether or not the ignition switch is off.

  If the determination result in step 100 is affirmative, the ECU 20 stops the fuel pump 4 in step 101, and closes the fuel cutoff valves 11, 12, 14, 18 in step 102. Thereby, in the storage site | part 13 of the fuel supply piping 5, the LPG fuel in a liquid state is hold | maintained in a pressurized state.

  On the other hand, if the determination result in step 100 is negative, in step 110, the ECU 20 determines whether or not the LPG engine 1 is being started. The ECU 20 makes this determination based on, for example, whether or not the ignition switch is on.

  If the determination result in step 110 is affirmative, the ECU 20 drives the fuel pump 4 in step 111, and in step 112, of the fuel cutoff valves 11, 12, 14, and 18, the ECU 20 delivers the fuel pump 4. The side fuel cutoff valve 12 is opened. As a result, the LPG fuel held in the pressurized state in the storage portion 13 of the fuel supply pipe 5 is released, and when the LPG engine 1 is started, the pressurized LPG fuel is supplied to the delivery pipe 7 and each injector 6 at once. Is done. At this time, since the return fuel cutoff valve 14 is closed, the pressure of the LPG fuel in the delivery pipe 7 quickly becomes higher than the normal pressure.

  On the other hand, if the determination result in step 110 is negative, in step 120, the ECU 20 determines whether or not the LPG engine 1 has been started. The ECU 20 makes this determination based on, for example, the engine rotation speed detected by the rotation speed sensor.

  If the determination result in step 120 is affirmative, the ECU 20 drives the fuel pump 4 in step 121, and in step 122, among the fuel cutoff valves 11, 12, 14, 18, the tank side fuel cutoff valve 11, delivery The side fuel cutoff valve 12 and the return fuel cutoff valve 14 are opened. As a result, the remaining fuel that is not injected from each injector 6 by the delivery pipe 7 returns to the fuel tank 3 via the fuel return pipe 8. At this time, since the bypass fuel cutoff valve 18 is closed, the two pressure regulators 15 and 16 on the fuel return pipe 8 act on the LPG fuel, and the LPG fuel is adjusted to a relatively high pressure. .

  Thereafter, in step 123, the ECU 20 determines whether or not a “low pressure request” is made for the pressure of the LPG fuel. If the determination result is affirmative, the ECU 20 opens the bypass fuel cutoff valve 18 in step 124. As a result, the fuel that has passed through the upstream pressure regulator 15 bypasses the downstream pressure regulator 16 and flows through the bypass pipe 17, so that only one pressure regulator 15 acts on the LPG fuel, and the LPG fuel is relatively Adjusted to low pressure.

  As described above, according to the fuel supply device 2 of this embodiment, when the LPG engine 1 is started, the return fuel shutoff valve 14 shuts off the flow of LPG fuel in the fuel return pipe 8, thereby opening the storage site 13. By supplying the LPG fuel thus supplied to the delivery pipe 7 and each injector 6, the pressure of the supplied fuel is quickly increased. For this reason, only when the LPG engine 1 is started, the LPG fuel pressure can be increased earlier than during normal operation after starting.

  In this embodiment, the bypass fuel cutoff valve provided corresponding to the downstream pressure regulator 16 of the two pressure regulators 15 and 16 of the fuel return pipe 8 after the LPG engine 1 is started, that is, during normal operation. By selectively opening and closing 18, the downstream pressure regulator 16 is selectively functioned. For this reason, the pressure of the LPG fuel in the delivery pipe 7 can be variably set in two stages.

[Second Embodiment]
Next, a second embodiment of the fuel supply device according to the present invention will be described in detail with reference to the drawings.

  In each of the following embodiments including this embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted. Hereinafter, different points will be mainly described.

  FIG. 5 is a schematic configuration diagram showing the fuel supply device in this embodiment. This embodiment differs from the first embodiment in the configuration associated with the fuel return pipe 8. In other words, in this embodiment, the fuel return pipe 8 is provided with one pressure regulator 31 and one return fuel cutoff valve 32 arranged in series. The pressure regulator 31 is disposed on the upstream side of the return fuel cutoff valve 32. The return fuel cutoff valve 32 is connected to the ECU 20. What is characteristic in this embodiment is that the arrangement direction of the return fuel cutoff valve 32 is opposite to that of the return fuel cutoff valve 14 in the first embodiment. That is, as shown in FIG. 6, the basic structure of the return fuel cutoff valve 32 is the same as that of each of the fuel cutoff valves 11, 12, 14, 18 shown in FIG. 2, but the fuel flow direction (indicated by arrows). Are arranged in the valve opening direction of the valve body 24. With this arrangement, the valve body 24 of the return fuel cutoff valve 32 is opened by moving in the fuel flow direction, and is closed by moving in the direction opposite to the fuel flow direction. With this arrangement, the return fuel cutoff valve 32 has a fuel pressure regulating function for adjusting the pressure of the LPG fuel. That is, as shown in FIG. 7, when the fuel pressure is smaller than the spring pressure, the valve body 24 moves in the direction opposite to the fuel flow direction and closes. On the other hand, as shown in FIG. 8, when the fuel pressure is larger than the spring pressure, the valve body 24 moves in the fuel flow direction against the spring 25 and opens. The degree of valve opening is determined by the balance between the fuel pressure and the urging force of the spring 25. In this way, the return fuel cutoff valve 32 performs the fuel pressure regulation function. That is, the fuel return pipe 8 includes a return fuel cutoff valve 32 having a fuel pressure regulation function, and a single pressure regulator 31 that is provided separately from the fuel return pipe 8 and exhibits the original fuel pressure regulation function (pressure regulation function). Provided. The pressure regulator 32 corresponds to a separate pressure adjusting unit in the present invention.

  FIG. 9 is a flowchart showing the contents of the fuel supply control program executed by the ECU 20 in this embodiment. As shown in FIG. 9, this flowchart differs from the flowchart of FIG. 4 in that the processing of steps 123 and 124 shown in FIG. 4 is omitted. Therefore, when the engine is stopped, when the engine is started, and after the engine is started, the fuel cutoff valves 11, 12, 32 and the fuel pump 4 are controlled in the same manner as in the first embodiment.

  Therefore, according to the fuel supply device 2 of this embodiment, when the LPG engine 1 is started, the fuel pressure adjustment function of the return fuel cutoff valve 32 when the coil 26 is not energized and the fuel pressure adjustment of the separate pressure regulator 31 are performed. By cooperating with the pressure function, the LPG fuel pressure in the delivery pipe 7 and each injector 6 is adjusted to be relatively high. In addition, after the LPG engine 1 is started, the return fuel cutoff valve 32 is opened by energizing the coil 26, so that the LPG fuel pressure in the delivery pipe 7 and each injector 6 is obtained only by the fuel pressure regulating function by the separate pressure regulator 31. Is adjusted relatively low.

  That is, also in this embodiment, after the LPG engine 1 is started, that is, during normal operation, the return fuel shut-off valve 32 and the pressure regulator 31 in the fuel return pipe 8 are caused to exhibit the fuel pressure regulating function by the return fuel shut-off valve 32 in the fuel return pipe 8. As a result, the pressure of the LPG fuel in the delivery pipe 7 can be variably adjusted in two stages. Obtaining this two-stage fuel pressure regulation function is the same as in the first embodiment. In addition, in order to obtain a two-stage fuel pressure regulation function, in this embodiment, only one return fuel shut-off valve 32 and a separate pressure regulator 31 are provided on the fuel return pipe 8, respectively. Unlike the above, it is not necessary to provide the two pressure regulators 15, 16, the bypass pipe 17, and the bypass fuel cutoff valve 18, and the configuration of the fuel supply device 2 can be simplified by the amount omitted.

  In this embodiment, the solenoid valve constituting the return fuel cutoff valve 32 exhibits a fuel cutoff function and a fuel pressure regulation function. Therefore, the return fuel cutoff valve 32 and the separate pressure regulator 31 are connected to each other. It becomes possible to arrange in series. This also contributes to simplification of the configuration of the fuel supply device 2. Further, by changing the setting of the urging force of the spring 26 in the return fuel cutoff valve 32, the fuel pressure regulation value by the cutoff valve 32 can be easily changed. For this reason, according to the structural variation which concerns on the LPG engine 1, the fuel pressure regulation function by the return fuel cutoff valve 32 can be easily adapted.

  Further, in this embodiment, the arrangement direction of the return fuel cutoff valve 32 is opposite to the normal arrangement direction. For this reason, if the return fuel shut-off valve 32 is in a normal orientation, the fuel pressure in the delivery pipe 7 suddenly drops when the shut-off valve 32 is opened as shown in FIG. After that, there were concerns about engine stalls. On the other hand, in this embodiment, as shown in FIG. 11, even when the return fuel cutoff valve 32 is in the closed state, some fuel flows to the downstream side of the cutoff valve 32. When opened, the fuel pressure in the delivery pipe 7 does not drop too much, and the fuel pressure can be converged to a target value that does not cause engine stall.

[Third Embodiment]
Next, a third embodiment of the fuel supply device according to the present invention will be described in detail with reference to the drawings.

  FIG. 12 is a schematic configuration diagram showing the fuel supply device in this embodiment. This embodiment differs from the first embodiment in the configuration associated with the fuel supply pipe 5 and the fuel return pipe 8. In other words, in this embodiment, the storage site 13 of the fuel supply pipe 5 is provided with a relief pipe 41 that communicates with the fuel tank 3. The relief pipe 41 is provided with a relief valve 42. The relief valve 42 is opened to relieve the LPG fuel when the fuel pressure applied to the valve 42 exceeds a predetermined value. The relief pipe 41 and the relief valve 42 are the relief means of the present invention for relieving the LPG fuel held in the storage site 13 to the fuel tank 3 when the fuel pressure in the storage site 13 exceeds a predetermined value. It corresponds to. On the other hand, in this embodiment, unlike the second embodiment, the return fuel cutoff valve 32 is arranged upstream of the pressure regulator 31 in the fuel return pipe 8. In addition, a pressure sensor 43 for detecting the pressure of the LPG fuel is provided in the storage portion 13 of the fuel supply pipe 5. The pressure of the LPG fuel detected by the pressure sensor 43 is input to the ECU 20. Therefore, the ECU 20 can monitor the pressure of the LPG fuel in the storage region 13 based on the input signal related to the fuel pressure.

  FIG. 13 is a flowchart showing the contents of the fuel supply control program executed by the ECU 20 in this embodiment. In this flowchart, steps 103, 113, and 125 are provided in place of the processing of steps 102, 112, and 122 shown in FIG.

  That is, when the engine is stopped, the routine proceeds from step 101, and in step 103, the ECU 20 closes the tank side fuel cutoff valve 11 and the delivery side fuel cutoff valve 12, and opens the return fuel cutoff valve 32. At this time, the relief valve 42 of the relief pipe 41 is closed. One of the aims of the fuel supply device 2 when the engine is stopped is to maintain the LPG fuel in a liquid phase state by maintaining the upstream side of the delivery side fuel cutoff valve 12 at a high pressure (relief pressure by the relief valve 42). . Another aim is to adjust the LPG fuel that returns to the fuel tank 3 via the fuel return pipe 8 by the pressure regulator 31 so that the fuel pressure in the storage region 13 is lower than the relief pressure. This is to prevent fuel leakage.

  When the engine is started, the routine proceeds from step 111, and in step 113, the ECU 20 opens the tank side fuel cutoff valve 11 and the delivery side fuel cutoff valve 12, and closes the return fuel cutoff valve 32. At this time, the relief valve 42 of the relief pipe 41 is closed. The aim of the fuel supply device 2 when starting the engine is to cut off the LPG fuel that returns to the fuel tank 3 via the fuel return pipe 8, thereby increasing the fuel pressure in the delivery pipe 7 to be higher than the relief pressure by the relief valve 31. The LPG fuel is maintained in a liquid phase state.

  Further, after the engine is started, the routine proceeds from step 121 and in step 125, the ECU 20 opens the tank side fuel cutoff valve 11 and the delivery side fuel cutoff valve 12, and opens the return fuel cutoff valve 32. At this time, the relief valve 42 of the relief pipe 41 is closed. The aim of the fuel supply device 2 after the engine is started is to adjust the LPG fuel returning to the fuel tank 3 via the fuel return pipe 8 by the pressure regulator 31 to ensure the fuel flow rate with respect to the engine load.

  Therefore, according to the fuel supply device 2 of this embodiment, the fuel pressure in the storage region 13 does not become too high due to the action of the relief valve 42. For this reason, especially when the engine is stopped, the fuel pressure in the storage region 13 can be made lower than the relief pressure, and fuel leakage due to high pressure can be prevented in the fuel supply pipe 5 beforehand. Other functions and effects are basically the same as those of the first embodiment.

[Fourth Embodiment]
Next, a fourth embodiment in which the fuel supply device according to the present invention is embodied will be described in detail with reference to the drawings.

  In FIG. 14, the fuel supply apparatus in this embodiment is shown with a schematic block diagram. This embodiment differs from the third embodiment in the configuration associated with the fuel supply pipe 5. That is, in this embodiment, the relief pipe 41 and the relief valve 42 in the third embodiment are omitted. Instead, a check valve 44 is provided near the discharge port of the fuel pump 4 in the fuel supply pipe 5 in the fuel tank 3. Similarly, in the fuel tank 3, the fuel supply pipe 5 is provided with a relief valve 45 on the downstream side of the check valve 44.

  In this embodiment, the content of the fuel supply control program executed by the ECU 20 is basically the same as the flowchart of FIG. That is, when the engine is stopped, the ECU 20 closes the tank-side fuel cutoff valve 11 and the delivery-side fuel cutoff valve 12 and opens the return fuel cutoff valve 32. At this time, the check valve 44 and the relief valve 45 are closed. One of the aims of the fuel supply device 2 when the engine is stopped is to maintain the LPG fuel in the liquid phase state by maintaining the upstream side of the delivery side fuel cutoff valve 12 at a high pressure (relief pressure by the relief valve 45). . Another aim is to adjust the LPG fuel that returns to the fuel tank 3 via the fuel return pipe 8 by the pressure regulator 31 so that the fuel pressure in the delivery pipe 7 is lower than the relief pressure. This is to prevent fuel leakage.

  When the engine is started, the ECU 20 opens the tank-side fuel cutoff valve 11 and the delivery-side fuel cutoff valve 12 and closes the return fuel cutoff valve 32. At this time, the check valve 44 is opened and the relief valve 45 is closed. The aim of the fuel supply device 2 when starting the engine is to cut off the LPG fuel that returns to the fuel tank 3 via the fuel return pipe 8, thereby increasing the fuel pressure in the delivery pipe 7 to be higher than the relief pressure by the relief valve 31. The LPG fuel is maintained in a liquid phase state.

  Further, after the engine is started, the ECU 20 opens the tank side fuel cutoff valve 11 and the delivery side fuel cutoff valve 12 and opens the return fuel cutoff valve 32. At this time, the check valve 44 is opened and the relief valve 45 is closed. The aim of the fuel supply device 2 after the engine is started is to adjust the LPG fuel returning to the fuel tank 3 via the fuel return pipe 8 by the pressure regulator 31 to ensure the fuel flow rate with respect to the engine load.

  Therefore, according to the fuel supply device 2 of this embodiment, the fuel pressure in the storage region 13 does not become too high due to the action of the relief valve 45. For this reason, especially when the engine is stopped, the fuel pressure in the storage region 13 can be made lower than the relief pressure, and fuel leakage due to high pressure can be prevented in the fuel supply pipe 5 beforehand. Further, since the relief valve 45 is provided in the fuel supply pipe 5 in the vicinity of the discharge port of the fuel pump 4, unlike the third embodiment, the relief pipe 41 can be omitted, and the configuration is simplified accordingly. be able to. Furthermore, since the check valve 44 and the relief valve 45 are provided in the fuel tank 3, it is possible to reduce the criteria regarding the pressure resistance of the valve body constituting the valves 44 and 45.

[Fifth Embodiment]
Next, a fifth embodiment in which the fuel supply apparatus according to the present invention is embodied will be described in detail with reference to the drawings.

  FIG. 15 is a schematic configuration diagram showing the fuel supply device in this embodiment. In this embodiment, unlike the fuel supply device of the fourth embodiment, a relief pipe 46 communicating with the fuel tank 3 is provided for the fuel return pipe 8 upstream of the return fuel cutoff valve 32. The return pipe 46 is provided with another return fuel cutoff valve 47. The fuel cutoff valve 47 is connected to the ECU 20.

  FIG. 16 is a flowchart showing the contents of the fuel supply control program executed by the ECU 20 in this embodiment. In this flowchart, steps 104, 114, and 126 are provided in place of the processing of steps 103, 113, and 125 shown in FIG.

  That is, when the engine is stopped, the routine proceeds from step 101, and in step 104, the ECU 20 closes the tank side fuel cutoff valve 11 and the delivery side fuel cutoff valve 12, and returns the fuel cutoff valve 32 and another return fuel cutoff valve 47. Open the valve. At this time, the check valve 44 and the relief valve 45 are closed. One of the aims of the fuel supply device 2 when the engine is stopped is to maintain the LPG fuel in the liquid phase state by maintaining the upstream side of the delivery side fuel cutoff valve 12 at a high pressure (relief pressure by the relief valve 45). . Another aim is to adjust the LPG fuel that returns to the fuel tank 3 via the fuel return pipe 8 by opening another return fuel cutoff valve 47, and to reduce the fuel pressure in the delivery pipe 7 to the internal pressure of the fuel tank 3. Thus, fuel leakage from the delivery pipe 7 and each injector 6 is prevented. Another aim is to promote cooling of the delivery pipe 7 by vaporizing the fuel with the delivery pipe 7 under reduced pressure.

  Further, when starting the engine, the routine proceeds from step 111, and in step 114, the ECU 20 opens the tank side fuel cutoff valve 11 and the delivery side fuel cutoff valve 12, and returns the fuel cutoff valve 32 and another return fuel cutoff valve 47. Is closed. At this time, the check valve 44 is opened and the relief valve 45 is closed. The aim of the fuel supply device 2 when starting the engine is to cut off the LPG fuel that returns to the fuel tank 3 via the fuel return pipe 8, thereby increasing the fuel pressure in the delivery pipe 7 to be higher than the relief pressure by the relief valve 31. The LPG fuel is maintained in a liquid phase state.

  Further, after the engine is started, the routine proceeds from step 121, and in step 126, the ECU 20 opens the tank side fuel cutoff valve 11, the delivery side fuel cutoff valve 12, and the return fuel cutoff valve 32, and another return fuel cutoff valve. 47 is closed. At this time, the check valve 44 is opened and the relief valve 45 is closed. The aim of the fuel supply device 2 after the engine is started is to adjust the LPG fuel returning to the fuel tank 3 via the fuel return pipe 8 by the pressure regulator 31 to ensure the fuel flow rate with respect to the engine load.

  Therefore, according to the fuel supply device 2 of this embodiment, the LPG fuel in the delivery pipe 7 is returned to the fuel tank 3 via the return pipe 46 when the LPG engine 1 is stopped, so that the fuel pressure in the delivery pipe 7 is high. It won't be too much. For this reason, when the engine is stopped, the delivery pipe 7 and each injector 6 can prevent fuel leakage due to high pressure. Further, the LPG fuel is vaporized under reduced pressure in the delivery pipe 7, whereby the delivery pipe 7 is cooled. For this reason, liquefaction of the LPG fuel supplied to the delivery pipe 7 when the engine is started can be promoted. Other functions and effects are basically the same as those of the fourth embodiment.

[Sixth Embodiment]
Next, a sixth embodiment in which the fuel supply device according to the present invention is embodied will be described in detail with reference to the drawings.

  In FIG. 17, the fuel supply apparatus in this embodiment is shown with a schematic block diagram. In this embodiment, unlike the fuel supply device of the fifth embodiment, the tip of the relief pipe 46 provided for the fuel return pipe 8 upstream of the return fuel cutoff valve 32 is provided separately from the fuel tank 3. Connected to canister 48. A check valve 50 is provided in the atmospheric port of the canister 48. A purge pipe 49 is provided between the canister 48 and the intake pipe (not shown) of the LPG engine 1. A purge control valve 51 is provided in the purge pipe 49. When the LPG engine 1 is stopped, the return fuel cutoff valve 47 and the purge control valve 51 are opened so that the fuel remaining in the delivery pipe 7 is collected in a canister 48 separate from the fuel tank 3. It has become. In this embodiment, the relief pipe 46, another return fuel cutoff valve 47, the purge control valve 51, and the canister 48 correspond to the fuel collecting means of the present invention.

  In this embodiment, the content of the fuel supply control program executed by the ECU 20 is basically the same as the flowchart of FIG. That is, when the engine is stopped, the ECU 20 closes the tank side fuel cutoff valve 11 and the delivery side fuel cutoff valve 12 and opens the return fuel cutoff valve 32, another return fuel cutoff valve 47 and the purge control valve 51. At this time, the check valve 44 and the relief valve 45 are closed. One of the aims of the fuel supply device 2 when the engine is stopped is to maintain the LPG fuel in the liquid phase state by maintaining the upstream side of the delivery side fuel cutoff valve 12 at a high pressure (relief pressure by the relief valve 45). . Another aim is to adjust the LPG fuel that returns to the fuel tank 3 via the fuel return pipe 8 by opening another return fuel shut-off valve 47 and purge control valve 51, and to adjust the fuel pressure in the delivery pipe 7 to the canister 48. It is to prevent fuel leakage from the delivery pipe 7 and each injector 6 by dropping to the atmospheric pressure that acts. Another aim is to promote cooling of the delivery pipe 7 by vaporizing the fuel with the delivery pipe 7 under reduced pressure.

  When the engine is started, the ECU 20 opens the tank-side fuel cutoff valve 11 and the delivery-side fuel cutoff valve 12 and closes the return fuel cutoff valve 32 and another return fuel cutoff valve 47. At this time, the check valve 44 is opened and the relief valve 45 is closed. The aim of the fuel supply device 2 when starting the engine is to cut off the LPG fuel that returns to the fuel tank 3 via the fuel return pipe 8, thereby increasing the fuel pressure in the delivery pipe 7 to be higher than the relief pressure by the relief valve 31. The LPG fuel is maintained in a liquid phase state.

  Further, after the engine is started, the ECU 20 opens the tank-side fuel cutoff valve 11, the delivery-side fuel cutoff valve 12, and the return fuel cutoff valve 32, and closes another return fuel cutoff valve 47. At this time, the check valve 44 is opened and the relief valve 45 is closed. The aim of the fuel supply device 2 after the engine is started is to adjust the LPG fuel returning to the fuel tank 3 via the fuel return pipe 8 by the pressure regulator 31 to ensure the fuel flow rate with respect to the engine load.

  Therefore, according to the fuel supply device 2 of this embodiment, the LPG fuel in the delivery pipe 7 is collected in the canister 48 via the return pipe 46 when the LPG engine 1 is stopped, so that the fuel pressure in the delivery pipe 7 is reduced. It will not be too high. For this reason, when the engine is stopped, the delivery pipe 7 and each injector 6 can prevent fuel leakage due to high pressure. Further, the LPG fuel is vaporized under reduced pressure in the delivery pipe 7, whereby the delivery pipe 7 is cooled. For this reason, liquefaction of the LPG fuel supplied to the delivery pipe 7 when the engine is started can be promoted. Further, when the LPG engine 1 is in operation, the purge control valve 51 can be opened as needed to purge the fuel collected in the canister 48 to the intake pipe via the purge pipe 49 and supply it to the LPG engine 1. Become. At this time, in the canister 48, the intake of the atmosphere is allowed by the check valve 50 and the fuel is prevented from escaping, so that the fuel can be purged. For this reason, the fuel collected by the canister 48 can be processed without waste. Other functions and effects are basically the same as those of the fourth embodiment.

  The present invention is not limited to the above-described embodiments, and a part of the configuration can be changed as appropriate without departing from the spirit of the invention. For example, in each of the embodiments described above, the fuel storage site is the upstream of the fuel supply site of the injector 6 and the delivery pipe 7, but the portion including the fuel supply site may be the fuel storage site.

The schematic block diagram which shows a fuel supply apparatus. Sectional drawing which shows a fuel cutoff valve. Explanatory drawing which shows a part of FIG. The flowchart which shows a fuel supply control program. The schematic block diagram which shows a fuel supply apparatus. Sectional drawing which shows a fuel cutoff valve. Sectional drawing which shows a part of fuel cutoff valve. Sectional drawing which shows a part of fuel cutoff valve. The flowchart which shows a fuel supply control program. The graph which shows the behavior of fuel pressure and engine speed. The graph which shows the behavior of fuel pressure and engine speed. The schematic block diagram which shows a fuel supply apparatus. The flowchart which shows a fuel supply control program. The schematic block diagram which shows a fuel supply apparatus. The schematic block diagram which shows a fuel supply apparatus. The flowchart which shows a fuel supply control program. The schematic block diagram which shows a fuel supply apparatus.

Explanation of symbols

1 LPG engine (internal combustion engine)
2 Fuel supply device 3 Fuel tank 4 Fuel pump 5 Fuel supply pipe (fuel supply path)
6 Injector (fuel supply area)
7 Delivery pipe (fuel supply area)
8 Fuel return piping (fuel return path)
11 Tank side fuel cutoff valve 12 Delivery side fuel cutoff valve 13 Storage part 14 Return fuel cutoff valve (shutoff means)
24 Valve body 25 Spring (biasing member)
31 Pressure regulator (separate pressure regulator)
32 Return fuel shutoff valve 41 Relief piping (relief means)
42 Relief valve (relief means)
46 Relief piping (fuel collecting means)
47 Another return fuel shut-off valve (fuel collecting means)
48 canister (fuel collecting means)

Claims (7)

The fuel in the fuel tank is supplied to the fuel supply site by the fuel pump via the fuel supply path, and when the internal combustion engine is stopped, the fuel is supplied to the storage site including a part or all of the fuel supply path to the fuel supply site. In a pressurized state, and at the time of starting the internal combustion engine, the fuel in the storage part is released to supply liquid fuel from the fuel supply part to the internal combustion engine.
A fuel supply apparatus comprising: a fuel return path for returning fuel from the fuel supply site to a fuel tank; The fuel supply apparatus according to claim 1, wherein the shut-off means has a fuel pressure regulation function, and a separate pressure regulation means is provided in the fuel return path. The said shut-off means is an electromagnetic valve including a valve body that opens by acting in the same direction as the fuel flow and closes by a biasing member by acting in the opposite direction to the fuel flow. Item 3. The fuel supply device according to Item 2. The fuel supply according to any one of claims 1 to 3, further comprising a relief means for relieving the fuel in the storage portion to the fuel tank when the fuel pressure in the storage portion becomes a predetermined value or more. apparatus. 5. The fuel supply device according to claim 1, wherein when the internal combustion engine is stopped, the fuel remaining in the fuel supply portion is returned to the fuel tank through the fuel return path. 6. 5. The fuel supply according to claim 1, further comprising a fuel collecting unit that collects fuel remaining in the fuel supply portion separately from the fuel tank when the internal combustion engine is stopped. 6. apparatus. The fuel supply device according to any one of claims 1 to 6, wherein the shut-off means is closed when the internal combustion engine is started and opened after the internal combustion engine is started.

Images