JP7400915B1 - Pump system and vehicle equipped with it - Google Patents

Abstract

The present invention suppresses the occurrence of pressure pulsations when driving a double-acting cylinder while reducing the number of pump units connected to a plurality of flow paths. A pump system 100 includes a pump unit 10, a pressure accumulator 30, a double-acting cylinder 20 having a first chamber 22 and a second chamber 23, first flow paths L1a, L1b, and a second flow path. L1c, L1d, a third flow path L1e that connects the second flow paths L1c, L1d and the fluid tank 70, a fourth flow path L2, and a connection point between the second flow paths L1c, L1d and the third flow path L1e. The three-way valve 24 and the control section 60 are provided. When the three-way valve 24 sends fluid from the pump unit 10 to the first chamber 22, the flow path is switched so that the fluid flows from the second flow path L1d to the second flow path L1c. 23, the flow path can be switched so that the fluid flows from the second flow path L1c to the third flow path L1e. [Selection diagram] Figure 2

Description

The present disclosure relates to a pump system and a vehicle equipped with the same.

BACKGROUND ART Conventionally, multi-system pumps having a pump function and a motor function are known. Such multi-system pumps can control the flow rate of multiple systems connected to the pump, and the number of pump systems can be adjusted depending on the number of hydraulic cylinders, hydraulic motors, pressure accumulators, etc. in the installed equipment. Need to decide.

Here, a conventional example in which a multi-system pump is applied to a forklift will be described using FIGS. 5 and 6. Vehicle 101 shown in FIG. 5 is a forklift truck equipped with pump system 200 shown in FIG. 6. FIG. 6 is a hydraulic circuit diagram showing a conventional pump system 200, and is an example in which the pump system 200 is mounted on a forklift.

The conventional pump system 200 includes a pump unit 10 having a motor section 11 and a pump section 12, a fluid tank 70 connected to the pump unit 10, and a control section 160 that controls the pump unit 10. The pump unit 10 is also connected to a pressure accumulator 30 via a flow path L13, connected to a single-acting cylinder 40 for lift via a flow path L14, and connected to a hydraulic motor for driving tires via a flow path L15. 50 is connected. Further, the pump unit 10 is configured to drive the double-acting cylinder 20 for tilting using two systems, a flow path L11 and a flow path L12.

Furthermore, Patent Document 1 discloses that a pressure accumulator and a first chamber of a double-acting cylinder are connected by a communication passage, and that a high-pressure port of a first actuating part that can switch between a function as a pump and a function as a motor; It is disclosed that the communication path is communicated. Further, Patent Document 1 discloses that the first actuating section is made to function as a pump to supply fluid to the second chamber of the double-acting cylinder, and discharge fluid in the first chamber to the pressure accumulator via a communication path. By doing so, the piston of the double-acting cylinder is moved in one direction, the first actuating section is made to function as a motor, and fluid is supplied from the pressure accumulator to the first chamber via the communication path. , it is disclosed that the piston of the double-acting cylinder is moved in the other direction by discharging the fluid in the second chamber to the outside.

JP 2021-55693 Publication

As the number of systems included in a pump increases, the size of the pump and the number of parts (for example, valve parts, piping parts, controllers, wiring parts, etc.) increase, and manufacturing costs also increase. Therefore, there is a need to configure a pump with as few systems as possible.

The number of systems is determined according to the number of cylinders and motors required for the installed equipment, but double-acting cylinders use two systems for operation, so equipment equipped with many double-acting cylinders requires The number of strains tends to increase. In particular, construction machinery and the like are equipped with many double-acting cylinders, so when applying multi-system pumps, the number of systems tends to increase.

In Patent Document 1, the number of systems is reduced by connecting both the pressure accumulator and the first chamber of the double-acting cylinder to the first actuating section via a common communication path. However, the fluid pressure circuit device described in Patent Document 1 has a problem in suppressing pressure pulsations when the fluid in the first chamber is discharged to the pressure accumulator via the communication path and the piston is moved toward the first chamber. , there was room for improvement.

The present disclosure has been made in view of the above problems. That is, an object of the present disclosure is to suppress the occurrence of pressure pulsations when driving a double-acting cylinder while reducing the number of pump units connected to a plurality of flow paths.

A pump system according to an embodiment of the present disclosure includes:
A pump unit connected to multiple flow paths,
A pressure accumulator for energy regeneration,
a double-acting cylinder having a first chamber and a second chamber;
a first flow path connecting the pump unit and the pressure accumulator;
a second flow path connecting the first chamber and the first flow path;
a third flow path connecting the second flow path and the fluid tank;
a fourth flow path connecting the pump unit and the second chamber;
a three-way valve provided at a connection point between the second flow path and the third flow path;
a control unit that controls switching of the flow path by the three-way valve,
The three-way valve, based on a control signal from the control section,
When sending fluid from the pump unit to the first chamber, the fluid is sent from the second flow path closer to the first flow path than the three-way valve to the second flow path closer to the first chamber than the three-way valve. The flow path can be switched so that the
When sending fluid from the pump unit to the second chamber, the flow path is switched so that the fluid flows from the second flow path closer to the first chamber than the three-way valve to the third flow path.

According to the present disclosure, it is possible to reduce the number of systems of pump units connected to a plurality of flow paths while suppressing the occurrence of pressure pulsations when driving a double-acting cylinder.

FIG. 1 is a schematic diagram showing a vehicle according to an embodiment of the present disclosure. FIG. 2 is a hydraulic circuit diagram showing a pump system according to an embodiment of the present disclosure. FIG. 3 is a schematic diagram showing an example of the operation of the double-acting cylinder in the pump system shown in FIG. 2. FIG. 4 is a schematic diagram showing another example of the operation of the double-acting cylinder in the pump system shown in FIG. 2. FIG. 5 is a schematic diagram showing an example of a vehicle equipped with a conventional pump system. FIG. 6 is a hydraulic circuit diagram showing an example of a conventional pump system.

Hereinafter, a pump system and a vehicle according to an embodiment of the present disclosure will be described with reference to the drawings. In each drawing, the same or equivalent components are denoted by the same reference numerals, and redundant explanations will be omitted as appropriate. Further, the dimensions of each component shown in each drawing are for convenience of explanation, and may differ from actual dimensions.

First, a pump system and a vehicle according to an embodiment of the present disclosure will be described using FIGS. 1 and 2. Vehicle 1 shown in FIG. 1 is a forklift truck equipped with pump system 100 shown in FIG. 2. A forklift is an example of a vehicle to which pump system 100 can be applied. Pump system 100 can also be applied to other vehicles such as hydraulic excavators. Furthermore, the pump system 100 may be applied to other machines such as machine tools and construction machines instead of vehicles.

As shown in FIG. 2, a pump system 100 according to an embodiment of the present disclosure includes a pump unit 10, a double-acting cylinder 20, a pressure accumulator 30, a single-acting cylinder 40, a hydraulic motor 50, and a control system. 60 and a fluid tank 70. The pump system 100 also includes first flow paths L1a, L1b, second flow paths L1c, L1d, third flow path L1e, fourth flow path L2, flow paths L3 to L5, and three-way valve 24. , and a check valve 25. In this embodiment, the pump system 100 is hydraulic and uses oil as the fluid, but the pump system 100 may use other fluids than oil.

The pump unit 10 includes a motor section 11 and a pump section 12. The motor section 11 is an engine that serves as a driving source for the pump section 12 . The pump section 12 is, for example, a variable displacement pump, and is connected to a plurality of channels. The pump unit 10 performs pumping and motoring to each channel connected to the pump unit 10 based on a control signal from the control section 60 .

The pressure accumulator 30 is provided for energy regeneration and can store fluid at high pressure. The pressure accumulator 30 is connected to the pump section 12 via first channels L1a and L1b. The first flow paths L1a and L1b are connected to the first chamber 22 via the second flow paths L1c and L1d. The first flow path L1a is a flow path closer to the pump unit 10 than the connection point between the first flow paths L1a, L1b and the second flow path L1d. The first flow path L1b is a flow path closer to the pressure accumulator 30 than the connection point between the first flow paths L1a, L1b and the second flow path L1d. Further, as will be described in detail later, the pressure accumulator 30 is involved in the piston movement of the double-acting cylinder 20.

The single-acting cylinder 40 is a cylinder for lifting, and is involved in the lifting operation of a fork of a forklift. The single-acting cylinder 40 is connected to the pump section 12 via a flow path L4. The hydraulic motor 50 is a motor for driving the tires of a forklift. Hydraulic motor 50 is connected to pump section 12 via flow path L5. The fluid tank 70 stores oil used as a fluid. In this embodiment, the fluid tank 70 is connected to the pump section 12 via a plurality of channels.

The double-acting cylinder 20 is involved in the tilting movement of the fork of the forklift. The double-acting cylinder 20 has a piston 21, a first chamber 22, and a second chamber 23. The first chamber 22 is connected to the first channels L1a, L1b via second channels L1c, L1d having a three-way valve 24. The second flow path L1c is a flow path closer to the double-acting cylinder 20 than the three-way valve 24. The second flow path L1d is a flow path closer to the pump unit 10 than the three-way valve 24. The third flow path L1e is connected to the three-way valve 24, and communicates the second flow paths L1c, L1d with the fluid tank 70. The check valve 25 is provided on the third flow path L1e. The second chamber 23 is connected to the pump section 12 via the fourth flow path L2.

The three-way valve 24 is provided at a connection point between the second flow path L1c, L1d and the third flow path L1e. Based on a control signal from the control unit 60, the three-way valve 24 connects a path in which the second flow path L1c and the second flow path L1d communicate with each other, and a path in which the second flow path L1c and the third flow path L1e communicate with each other. and switch. The structure of the three-way valve 24 is not particularly limited, and any conventionally known structure can be adopted as appropriate. The check valve 25 regulates the flow from the fluid tank 70 toward the three-way valve 24 . The structure of the check valve 25 is not particularly limited, and any conventionally known structure can be adopted as appropriate. Furthermore, the check valve 25 regulates the minimum pressure within the flow path using cracking pressure. It is preferable that the cracking pressure of the check valve 25 is, for example, 0.2 to 5 MPa. Note that when the check valve 25 is closed, the pressure in the third flow path L1e is the same as the pressure in the fluid tank 70, and is, for example, about atmospheric pressure.

The control unit 60 includes, for example, a CPU (Central Processing Unit), a ROM (Read Only Memory), and a RAM (Random Access Memory). The CPU reads a program according to the processing content from the ROM, loads it into the RAM, and performs various controls on the pump system 100 in cooperation with the loaded program.

The control unit 60 uses, for example, the operation of the forklift by the operator as input information, and controls the operations of the motor unit 11, the pump unit 12, and the three-way valve 24 based on the input information. For example, the control unit 60 outputs a control signal that controls the current supply to a solenoid valve (not shown) provided at a connection port with each flow path in the pump unit 12, and controls the opening and closing of the solenoid valve. Pumping and motoring for each channel can be controlled individually. The control unit 60 controls the operations of the motor unit 11 and the pump unit 12 based on input information, etc., so that the forklift performs various operations according to the operations of the operator. In addition, the control unit 60 outputs a control signal for switching the path within the three-way valve 24, for example, so that the second flow path L1c and the second flow path L1d communicate with each other, and the second flow path L1c and the second flow path L1d communicate with each other. Controls switching between the three flow paths L1e and the path that communicates with each other.

Next, the operation of the double-acting cylinder 20 in the pump system 100 shown in FIG. 2 will be described using FIGS. 3 and 4. FIG. 3 is a schematic diagram showing an example of the operation of the double-acting cylinder in the pump system shown in FIG. 2. Specifically, FIG. 2 is an example of the operation when the piston 21 is moved toward the first chamber 22 side.

In the example of FIG. 3, the pump unit 10 performs pumping to send out fluid to the fourth flow path L2, and makes the pressure on the second chamber 23 side higher than the pressure on the first chamber 22 side. When pumping to the fourth flow path L2, the three-way valve 24 is switched to a path that communicates the second flow path L1c and the third flow path L1e based on a control signal from the control unit 60. Then, the fluid in the first chamber 22 is pushed out to the second flow path L1c due to the pressure difference between the first chamber 22 side and the second chamber 23 side, and when the fluid reaches the cracking pressure of the check valve 25, It is sent to the fluid tank 70 through the third flow path L1e. The differential pressure generated by these operations causes the piston 21 to move toward the first chamber 22.

In the example of FIG. 3, the fluid on the first chamber 22 side is not drawn out by the motoring of the pump unit 10, but is sent to the fluid tank 70 by the differential pressure between the first chamber 22 and the fluid tank 70. . Therefore, sudden pressure changes in the first chamber 22 are less likely to occur than when motoring is performed by the pump unit 10, and it is possible to suppress the occurrence of pressure pulsations when driving the double-acting cylinder. Moreover, as a result, it is possible to suppress jerky cylinder operation and vibration of the cylinder, and similarly, it is possible to prevent the operational loss of the piston 21 from increasing.

Furthermore, by providing the check valve 25, it is possible to prevent the pressure in the first chamber 22 from becoming lower than necessary, and as a result, the occurrence of pressure pulsations when driving the double-acting cylinder is further suppressed. can do. As a result, it is possible to further suppress jerky cylinder operation and vibration of the cylinder, and similarly, it is possible to further prevent the operational loss of the piston 21 from increasing.

FIG. 4 is a schematic diagram showing another example of the operation of the double-acting cylinder 20 in the pump system 100 shown in FIG. 2. Specifically, FIG. 4 shows an example of the operation when the piston 21 is moved toward the second chamber 23 side.

In the example of FIG. 4, the pump unit 10 performs motoring on the fourth flow path L2 to remove fluid, and makes the pressure on the second chamber 23 side lower than the pressure on the first chamber 22 side. Further, when motoring is carried out to the fourth flow path L2, the three-way valve 24 is switched to a path that communicates the second flow path L1c and the second flow path L1d based on a control signal from the control unit 60. . Then, for example, the pump unit 10 performs pumping to the first flow path L1a to send out the fluid, and the fluid is supplied to the first chamber 22 through the second flow path L1c and the second flow path L1d. The differential pressure generated by these operations causes the piston 21 to move toward the second chamber 23.

Moreover, in the example of FIG. 4, when the pump unit 10 performs pumping to the first flow path L1a, a part of the fluid is sent to the pressure accumulator 30 through the first flow path L1b. When a sufficient amount of fluid is stored in the pressure accumulator 30, the fluid may be supplied from the pressure accumulator 30 to the first chamber 22 without pumping the first flow path L1a by the pump unit 10. . By supplying fluid from the pressure accumulator 30, it becomes easier to suppress the occurrence of pressure pulsations. Also, when the double-acting cylinder 20 is not operating, the three-way valve 24 is switched to a path that communicates the second flow path L1c and the third flow path L1e, and the pump unit 10 is connected to the first flow path L1a. By performing pumping, a sufficient amount of fluid may be stored in the pressure accumulator 30 in advance. Whether the fluid is supplied to the pump unit 10 or the pressure accumulator 30 depends on the control unit, for example, depending on the amount of fluid stored in the pressure accumulator 30, in other words, the amount of energy stored in the pressure accumulator 30. 60.

Although one embodiment according to the present disclosure has been described in detail above, the present invention is not limited to the above-described embodiment, and can be modified, improved, etc. as appropriate. For example, the pump system 100 may not include one or more of the single-acting cylinder 40 and the hydraulic motor 50, or may include other components. The present invention is defined by the scope of the claims, and includes all changes within the meaning and range equivalent to the scope of the claims.

[Additional notes]
As mentioned above, the following matters are disclosed in this specification.
(1) A pump unit connected to multiple channels,
A pressure accumulator for energy regeneration,
a double-acting cylinder having a first chamber and a second chamber;
a first flow path connecting the pump unit and the pressure accumulator;
a second flow path connecting the first chamber and the first flow path;
a third flow path connecting the second flow path and the fluid tank;
a fourth flow path connecting the pump unit and the second chamber;
a three-way valve provided at a connection point between the second flow path and the third flow path;
a control unit that controls switching of the flow path by the three-way valve,
The three-way valve, based on a control signal from the control section,
When sending fluid from the pump unit to the first chamber, the fluid is sent from the second flow path closer to the first flow path than the three-way valve to the second flow path closer to the first chamber than the three-way valve. The flow path can be switched so that the
When sending fluid from the pump unit to the second chamber, the flow path is switched so that the fluid flows from the second flow path closer to the first chamber than the three-way valve to the third flow path.
pump system.
According to this pump system, it is possible to reduce the number of pump units connected to a plurality of flow paths and to suppress the occurrence of pressure pulsations when driving a double-acting cylinder.
Specifically, the pressure accumulator and the first chamber are connected to the pump unit through a flow path branched by a three-way valve, thereby reducing the number of systems by one. Therefore, the pump system can be made more compact, lighter, and lower in cost.
In addition, when sending fluid from the pump unit to the second chamber, by switching the flow path so that the fluid flows from the second flow path on the first chamber side to the third flow path than the three-way valve, the first chamber side The fluid is not removed by the motoring of the pump unit, but is sent to the fluid tank by the differential pressure between the first chamber and the fluid tank. Therefore, sudden pressure changes in the first chamber are less likely to occur than when motoring is performed by the pump unit, and it is possible to suppress the occurrence of pressure pulsations when driving the double-acting cylinder. Further, as a result, for example, it is possible to suppress jerky cylinder operation and vibration of the cylinder, and similarly, it is possible to make it difficult to increase the operating loss of the piston.

(2) Further, a check valve is provided on the third flow path to regulate the flow in the direction toward the three-way valve.
The pump system according to (1) above.
According to this pump system, when the flow path is switched so that the fluid flows from the second flow path closer to the first chamber than the three-way valve to the third flow path, the pressure in the first chamber becomes lower than necessary. As a result, it is possible to further suppress the occurrence of pressure pulsations when driving the double-acting cylinder.

(3) A vehicle equipped with the pump system described in (1) or (2) above.
This vehicle is equipped with a pump system that can be made compact, lightweight, and low cost by reducing the number of systems, so the vehicle can be made compact, lightweight, and low cost. In addition, since the above pump system can suppress the occurrence of pressure pulsations in the double-acting cylinder, jerky cylinder operation and cylinder vibration are less likely to occur during vehicle operation, and operational loss in the double-acting cylinder is reduced. It becomes difficult to increase.

1,101: Vehicle 10: Pump unit 11: Motor section 12: Pump section 20: Double acting cylinder 21: Piston 22: First chamber 23: Second chamber 24: Three-way valve 25: Check valve 30: Pressure accumulator 40 : Single acting cylinder 50: Hydraulic motor 60, 160: Control unit 70: Fluid tank 100, 200: Pump system L1a, L1b: First flow path L1c, L1d: Second flow path L1e: Third flow path L2: Fourth flow path L3-5, L11-15: flow path

Claims (3)

A pump unit connected to multiple flow paths,
A pressure accumulator for energy regeneration,
a double-acting cylinder having a first chamber and a second chamber;
a first flow path connecting the pump unit and the pressure accumulator;
a second flow path connecting the first chamber and the first flow path;
a third flow path connecting the second flow path and the fluid tank;
a fourth flow path connecting the pump unit and the second chamber;
a three-way valve provided at a connection point between the second flow path and the third flow path;
a control unit that controls switching of the flow path by the three-way valve,
The three-way valve, based on a control signal from the control section,
When sending fluid from the pump unit to the first chamber, the fluid is sent from the second flow path closer to the first flow path than the three-way valve to the second flow path closer to the first chamber than the three-way valve. The flow path can be switched so that the
When sending fluid from the pump unit to the second chamber, the flow path is switched so that the fluid flows from the second flow path closer to the first chamber than the three-way valve to the third flow path.
pump system. Further, a check valve is provided on the third flow path for regulating flow in a direction toward the three-way valve.
A pump system according to claim 1. A vehicle comprising the pump system according to claim 1 or claim 2.

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