JP2023181948A - energy regeneration system - Google Patents

Abstract

To suppress an increase of a cost of a system and an increase of a necessary on-vehicle space, in the energy regeneration system of a hydraulic shovel.SOLUTION: Common drive shafts for driving working machine cylinders 12, 13 and 14, double-series variable displacement hydraulic pump motors 20, 21 and 22 having bi-directionally-tiltable swash plates, and a variable displacement hydraulic pump motor 23 connected to the variable displacement hydraulic pump motors 20, 21 and 22 having swirling/traveling bi-directionally-tiltable swash plates, and having a bi-directionally-tiltable swash plate are driven by a prime motor 18 via a gear device 19. A variable displacement hydraulic motor 24 connected to the gear device 19, and increased in a capacity accompanied by drive pressure is provided, a hydraulic accumulator 25 is provided at a hydraulic circuit located between and among the variable displacement hydraulic pump motor 23, the variable displacement hydraulic motor 24, and swirling/traveling variable displacement hydraulic pump motors 15, 16 and 17, thus pressure-accumulating regeneration energy at the hydraulic accumulator 25 by controlling a capacity of the variable displacement hydraulic pump motor 23 so that the input torque of the gear device 19 from the prime motor 18 does not become negative.SELECTED DRAWING: Figure 2

Description

The present invention relates to improvements in energy regeneration systems in hydraulic excavators.

As shown in FIG. 1, the hydraulic excavator has a structure in which an upper revolving body 1 including a boom 3, an arm 5, and a bucket 7, which are working machines, rotates with respect to a lower traveling body 2. As an example of basic work, the cycle of excavating earth and sand, lifting it, turning it, loading it onto a dump truck, turning it, and lifting it is repeated. During this cycle of loading work, the work equipment and the excavated earth and sand have potential energy as the work equipment lifts up. After loading onto the dump truck, the work equipment's potential energy is converted into heat as throttling loss by the hydraulic valve. It becomes energy. Moreover, the rotational inertia energy accompanying the swinging drive of the upper revolving body turns into thermal energy as throttling loss due to the hydraulic valve when the swinging is stopped.
Systems for regenerating these energies have been proposed. An example of this is Patent Document 1 (FIG. 6). The boom cylinder 53 is driven by a generator motor 57 driven by an internal combustion engine 56 via an AC/DC converter 58 and an inverter 59 to drive a dual pump 67 connected to the boom cylinder 53. The potential energy is regenerated as electrical energy by the generator motor 63. The rotation of the upper revolving body is driven by a generator motor 64 via an inverter 60, and rotational inertial energy is regenerated as electrical energy. These electrical energies are stored in a capacitor 69 via inverters 59 and 60 and a converter 68. The generator motors 65 and 66 are for driving the undercarriage. Further, the arm cylinder 54 and the bucket cylinder 55 are connected to a variable displacement hydraulic pump 70 and controlled via a hydraulic controller 71.

JP2002-242234

According to the system shown in FIG. 6, many electric power generators such as a generator motor 63 for the boom cylinder 53, a generator motor 64 for swinging, a generator motor 65, 66 for traveling, inverters 59, 60, 61, 62, a capacitor 69, etc. Equipment is required. Therefore, there are problems in that the cost of the system increases and the space required to be mounted on the vehicle increases.

Two variable displacement hydraulic pump motors with a common drive shaft and a swash plate that can tilt in both directions drive the boom, arm, and bucket cylinder, respectively, and a swash plate that can tilt in both directions for swinging or for swinging and traveling. A variable displacement hydraulic pump motor having a swash plate that can be tilted in both directions is driven by a common prime mover through a gear system, and a variable displacement hydraulic pump motor having a plate for driving a variable displacement hydraulic pump motor having a swash plate that can be tilted in both directions is driven by a common prime mover through a gear system. A hydraulic accumulator is provided in the hydraulic circuit between the variable displacement hydraulic pump motor and the variable displacement hydraulic pump motor, and a variable displacement hydraulic motor whose capacity increases in proportion to the driving pressure is connected to a gear device, and is used for swinging or for swinging and By controlling the capacity of the variable displacement pump motor that drives the variable displacement hydraulic pump motor for travel so that the driving pressure is at a predetermined value, and also so that the input torque from the prime mover of the gear device does not become negative. The regenerated energy is stored in a hydraulic accumulator.

By using a dual variable displacement hydraulic pump motor with a swash plate that can tilt in both directions, it is possible to control the rotation speed individually with a configuration driven by a common prime mover through a gear system, and also for turning or turning. A variable displacement hydraulic pump motor with a swash plate that can tilt in both directions for traveling is driven by a common prime mover through a gear system, and a variable displacement hydraulic pump motor whose capacity increases in proportion to the driving pressure. By combining the motors in a configuration that drives them at a constant pressure, it becomes possible to control individual rotations and to accumulate pressure in the accumulator of regenerated energy. It is possible to reduce the number of inverters, boom cylinder generator motors, inverters, capacitors, etc., thereby suppressing increases in system costs and required vehicle space.

It is a conceptual diagram of a hydraulic excavator. 1 is an embodiment (system diagram) of the present invention. FIG. 3 is an explanatory diagram of a control method. 1 is an embodiment of the present invention (outline diagram of a dual variable displacement hydraulic pump motor having a common drive shaft and a bidirectionally tiltable swash plate); FIG. 1 is a cross-sectional view of a dual variable displacement hydraulic pump motor with a common drive shaft and a bidirectionally tiltable swash plate according to an embodiment of the present invention; FIG. It is an example (system diagram) of a prior art document.

FIG. 1 is a conceptual diagram of a hydraulic excavator. The hydraulic excavator consists of an upper rotating body 1 and a lower traveling body 2, and the upper rotating body 1 includes a boom 3, a boom cylinder 4, an arm 5, an arm cylinder 6, a bucket 7, and a bucket cylinder 8. The upper rotating body 1 is rotated by a rotating motor 9, and the lower traveling body 2 is equipped with traveling motors 10 and 11.
FIG. 2 is a system diagram of an embodiment of the device of the present invention. The prime mover 18 is controlled to have a constant rotation.
One of the output ports of one of the two hydraulic pump motors constituting a dual variable displacement hydraulic pump motor connected to each of the boom cylinder 12, arm cylinder 13, and bucket cylinder 14 is connected to the head side of the hydraulic cylinder. The other output port communicates with the tank port, one of the output ports of the other hydraulic pump motor communicates with the head side of the hydraulic cylinder, and the other output port communicates with the rod side of the hydraulic cylinder. In this structure, the ratio of the capacity to the head side and the capacity to the rod side is set to the ratio of the pressure receiving area on the head side and the pressure receiving area on the rod side of the hydraulic cylinder. The expansion and contraction of the cylinders is controlled by changing the capacity of these hydraulic pump motors.
A variable displacement hydraulic pump motor 23 with a common drive shaft and a bidirectionally tiltable swashplate, 20 , 21 , 22 and a bidirectionally tiltable swashplate, is driven by the prime mover 18 via a gearing 19 .
Further, a variable displacement hydraulic motor 24 is connected to the gear device 19 . The output of the variable displacement hydraulic motor 24 is output to the gear system, and no loss occurs due to the flow rate flowing through this hydraulic motor.
The variable displacement hydraulic pump motor 23 and the variable displacement hydraulic motor 24 include a variable displacement hydraulic pump motor 15 having a bidirectionally tiltable swash plate that drives the upper rotating body, and a bidirectionally tiltable swash plate that drives the lower rotating body. Variable displacement hydraulic pump motors 16 and 17 having plates are connected, and a hydraulic accumulator 25 for accumulating regenerative energy is connected to the hydraulic circuit thereof.
The driving pressures of the variable displacement hydraulic pump motors 15, 16, and 17 for swinging and traveling are controlled to be constant by controlling the flow rate flowing through the variable displacement hydraulic motor 24 by the variable displacement hydraulic pump motor 23. Specifically, the flow rate from the variable displacement hydraulic pump motor 23 is increased by a constant flow rate less than the maximum flow rate that the hydraulic motor 24 can flow relative to the total flow rate of the variable displacement pump motors 15, 16, and 17 for swinging and traveling. Control the flow. This constant flow will flow through the variable displacement hydraulic motor 24. FIG. 3-1 shows the relationship between the capacity and driving pressure of the variable displacement hydraulic motor 24. The driving pressure becomes P1 at the capacity q0, and the variable displacement hydraulic motor 24 reaches its maximum capacity. Since the product of the capacity and the rotational speed is the flow rate, the driving pressure to flow the constant flow rate is determined. In this way, the driving pressures of the variable displacement pump motors 15, 16, and 17 for swinging and traveling are controlled to be greater than or equal to P0 and less than or equal to P1. By controlling the tilting angles of the variable displacement pump motors 15, 16, and 17 with respect to this driving pressure, the driving torque is controlled and turning and traveling are controlled.
These variable displacement hydraulic pump motors are equipped with a brake and a torque sensor, and control is performed to hold the pump when stopped and to prevent reverse rotation when starting.
The regenerated energy from the work machine cylinders 12, 13, and 14 is mutually used by the work machine cylinders 12, 13, and 14 via the gear device 19, and is also used for rotation via the gear device 19 and the variable displacement hydraulic pump motor 23. , and are used in variable displacement hydraulic pump motors 15, 16, and 17 for travel. In addition, the regenerated energy from the variable displacement hydraulic pump motors 15, 16, 17 for swinging and traveling is mutually used by the variable displacement hydraulic pump motors 15, 16, 17 for swinging and traveling, and the variable displacement hydraulic pump motor 23, gear It is utilized by the working machine cylinders 12, 13, 14 via the device 19. If there is a surplus of regenerated energy, it is accumulated in the hydraulic accumulator 25.
Specifically, when a surplus of regenerative energy occurs, the input torque from the prime mover 18 to the gear device 19 becomes negative, so the capacity of the variable displacement hydraulic pump motor 23 is reduced to the prime mover of the gear device 19, as shown in FIG. 3-2. In order to prevent the input torque from the variable displacement hydraulic pump motor 23 from becoming negative, the capacity q is increased by Δq/Δt with respect to the value at the time of the drive pressure control described above, and the input torque of the variable displacement hydraulic pump motor 23 is increased. P1 at the maximum displacement q0 of the characteristics of the variable displacement hydraulic motor 24 shown in FIG. 3-1 is set to the minimum accumulated pressure of the hydraulic accumulator 25. The driving pressure increases due to the increase in capacity, and after the capacity of the variable capacity hydraulic motor 24 reaches the maximum capacity q0, the flow rate corresponding to the increase in the capacity of the variable capacity hydraulic pump motor 23 is accumulated in the accumulator 25.
If the capacity of the hydraulic accumulator 25 is set to a value greater than or equal to the maximum value of surplus regenerative energy in the assumed cycle work, in principle only the energy required for excavation and lifting of earth and sand will be consumed, resulting in a significant reduction in energy consumption. Become.
4 and 5 are an external view and a sectional view of a dual variable displacement hydraulic pump motor for a working machine cylinder. 41 and 42 are cylinder connection ports, and 47 is a tank port.
The variable displacement hydraulic pump motors 29 and 30 are driven by a common drive shaft 28, and a common swash plate 31 supported by a trunnion 32 is tilted and controlled by a servo piston 33 via a slider 34 to maintain a constant ratio. The capacitance changes while maintaining .
The output port 43 of the hydraulic pump motor 29 communicates with the head side of the hydraulic cylinder, the other output port communicates with the tank port 47 through the inside of the case 39, and the output port 44 of the hydraulic pump motor 30 communicates with the head side of the hydraulic cylinder. The other output port merges with the output port 43 of the hydraulic pump motor 29 via a communication path 40 and communicates with the head side of the hydraulic cylinder. In this configuration, the ratio of the capacity to the head side, which is the sum of the capacity of the hydraulic pump motor 29 and the capacity of the hydraulic pump motor 30, to the capacity to the rod side, which is the capacity of the hydraulic pump motor 30, is equal to the capacity of the hydraulic cylinder head side. It is set to the ratio of the pressure receiving area and the pressure receiving area on the rod side.
The tilt angle of the swash plate 31 is controlled by electromagnetic control valves 50 and 51 and a tilt angle sensor 52 provided on the trunnion 32 to measure the tilt angle of the swash plate 31.
If the flow rate from the cylinder chamber is larger than the suction flow rate of the hydraulic pump motor due to machining errors, etc., muffled pressure will be generated, and if it is smaller, negative pressure will be generated. On the other hand, in the servo piston 33 that controls the swash plate 31, the output port 43 of the hydraulic pump motor 29 and the output port 44 of the hydraulic pump motor 30 are connected to the tank port 47 through the inside of the case 39, and the swash plate 31 is connected to the tank port 47 through the inside of the case 39. Cutouts 35 and 36 are provided that communicate with each other at 0 degrees and at the suction position to suppress the generation of trapped pressure. Further, there are passages provided with check valves 45 and 46 between the output ports 43 and 44 of the hydraulic pump motor and the connection ports 41 and 42 of the hydraulic cylinder, and the passages are closed by the servo piston when the tilt angle is 0 degrees. A passage is provided which is opened by a cutout in the servo piston when the swash plate is in the suction position.
Regarding negative pressure, suction valves 48 and 49 are provided at connection ports 41 and 42 connected to the hydraulic cylinders, and are communicated with the tank port 47 through the inside of the case 39 to prevent negative pressure.

1 Upper rotating body 2 Lower traveling body 3 Boom 4 Boom cylinder 5 Arm 6 Arm cylinder 7 Bucket 8 Bucket cylinder 9 Swing motor 10 Travel motor 11 Travel motor 12 Boom cylinder 13 Arm cylinder 14 Bucket cylinder 15 Variable displacement hydraulic pump motor for swing 16 Traveling variable displacement hydraulic pump motor 17 Traveling variable displacement hydraulic pump motor 18 Prime mover 19 Gear system 20 Dual variable displacement hydraulic pump motor for boom 21 Dual variable displacement hydraulic pump motor for arm 22 Dual variable displacement hydraulic pump motor for bucket 23 Variable displacement hydraulic pump motor that drives the variable displacement hydraulic pump motor for swinging and traveling 24 Variable displacement hydraulic motor for pressure control 25 Hydraulic accumulator for regeneration 26 Charge pump 27 Hydraulic accumulator for charge pump 28 Common drive shaft 29 Variable displacement hydraulic pump Motor 30 Variable displacement hydraulic pump motor 31 Common swash plate 32 Trunnion 33 Servo piston 34 Slider 35 Notch 36 Notch 37 Notch 38 Notch 39 Case 40 Communication path 41 Cylinder connection port 42 Cylinder connection port 43 Output port 44 Output port 45 Check valve 46 Check valve 47 Tank port 48 Suction valve 49 Suction valve 50 Electromagnetic proportional control valve 51 Electromagnetic proportional control valve 52 Swash plate angle sensor 53 Boom cylinder 54 Arm cylinder 55 Bucket cylinder 56 Internal combustion engine 57 Generator motor 58 AC/DC conversion device 59 Boom inverter 60 Swing inverter 61 Travel inverter 62 Travel inverter 63 Boom generator motor 64 Swing generator motor 65 Travel generator motor 66 Travel generator motor 67 Boom dual pump motor 68 Converter 69 Capacitor 70 Variable displacement pump 71 for arm and bucket Hydraulic controller

Claims (5)

This is an energy regeneration system for a hydraulic excavator, which includes a dual variable displacement hydraulic pump motor with a common drive shaft and a swash plate that can tilt in both directions, which drives the work machine cylinder, and a hydraulic pump motor for swinging or for swinging and traveling. Driving a variable displacement hydraulic pump motor with a bidirectionally tiltable swashplate An energy regeneration system in which variable displacement hydraulic pump motors with a bidirectionally tiltable swashplate are driven by a common prime mover through a gear system. 2. The energy regeneration system according to claim 1, wherein a hydraulic accumulator is provided in a hydraulic circuit that drives a variable displacement hydraulic pump motor for swinging or for swinging and traveling. In claim 2, a hydraulic circuit for driving a variable displacement hydraulic pump motor for swinging or for swinging and traveling is provided with a variable displacement hydraulic motor connected to the gear device and whose capacity increases in proportion to the driving pressure. By controlling the capacity of the variable displacement pump motor that drives the variable displacement hydraulic pump motor for swinging or for swinging and traveling, the drive pressure is set to a predetermined value and the input torque from the prime mover of the gear device is controlled. An energy regeneration system that stores regenerative energy in the hydraulic accumulator by controlling the capacity of the variable displacement pump motor so that the pressure does not become negative. The output hydraulic circuit of the variable displacement hydraulic pump motor is provided with a variable displacement hydraulic motor whose drive shaft is coupled directly or through a gear device and whose capacity increases as the driving pressure increases, and the variable displacement hydraulic pump motor A hydraulic system that controls driving pressure by controlling the capacity of Of the output ports of one of the two hydraulic pump motors that drive the hydraulic cylinder, one communicates with the head side of the hydraulic cylinder, and the other output port communicates with the tank port through the inside of the case. One of the output ports of the other hydraulic pump motor communicates with the head side of the hydraulic cylinder, and the other output port communicates with the rod side of the hydraulic cylinder. The capacity ratio is set to the ratio of the pressure receiving area on the head side of the hydraulic cylinder and the pressure receiving area on the rod side, and it has a common drive shaft and a swash plate that can be tilted in both directions, and the piston for controlling the swash plate has a configuration. The output port where the two hydraulic pump motors are combined and the output port of one hydraulic pump motor communicate with the tank port through the inside of the case and a predetermined area at the swash plate's 0 degrees and the suction position. A notch is provided to suppress the generation of trapped pressure, and the connection port between the output port of the hydraulic pump motor and the hydraulic cylinder is closed by a passage equipped with a check valve and a servo piston when the tilt angle is 0 degrees. , A passage is provided that opens through a notch in the servo piston when the swash plate is in the suction position, and a suction valve is provided at the cylinder connection port and communicates with the tank port through the case to prevent negative pressure. Variable displacement hydraulic pump motor.