EP4752379A1

EP4752379A1 - Fluid pressure circuit

Info

Publication number: EP4752379A1
Application number: EP24845298.9A
Authority: EP
Inventors: Koji Sato; Yoshiyuki Shimada; Tatsuhiro Arikawa
Original assignee: Eagle Industry Co Ltd
Current assignee: Eagle Industry Co Ltd
Priority date: 2023-07-25
Filing date: 2024-06-26
Publication date: 2026-06-03
Also published as: JPWO2025022916A1; CN121399380A; WO2025022916A1; KR20260027331A

Abstract

A fluid pressure circuit in which efficiency of pressure accumulation is high is provided. A fluid pressure circuit 100 includes a plurality of drive portions 5, 6, 7 connected to a single load 4, and an accumulator 10 configured for accumulating pressure. The drive portions 5, 6, 7 include at least one drive portion 7 of which a return flow passage 23-2 branches and is connected to the accumulator 10.

Description

{TECHNICAL FIELD}

The present invention relates to a fluid pressure circuit, for example, a fluid pressure circuit including an accumulator for accumulating pressure of a working fluid.

{BACKGROUND ART}

In various fields, a fluid pressure circuit in which a working fluid such as a working oil fed from a fluid supply device such as a pump is utilized and an actuator is driven is known. In such a fluid pressure circuit, for example, pressure of an oil discharged from the hydraulic cylinder device following a contraction action of a hydraulic cylinder device serving as the actuator is accumulated in an accumulator and regeneration is also performed at the time of an extension action of the hydraulic cylinder device.
For example, a fluid pressure circuit illustrated in Patent Citation 1 mainly includes a pump, a control valve, two boom cylinders, an accumulator, and a valve. When an operation lever is operated to the lowering side, the control valve is switched to a lowering position, an oil from the pump is supplied to rod side oil chambers of the two boom cylinders, and oils of head side oil chambers are discharged. Thereby, the two boom cylinders are lowered, and a boom is driven and lowered. Pressure of part of the oils discharged from the head side oil chambers is accumulated in the accumulator through the valve, and the other part is discharged to the tank.
Also, when the operation lever is operated to the raising side, the control valve is switched to a raising position, the oil from the pump is supplied to the head side oil chambers of the two boom cylinders, and the oils from the rod side oil chambers are discharged to the tank. Also, at this time, the valve is opened, and the oil whose pressure is accumulated in the accumulator is regenerated in the head side oil chambers of the two boom cylinders. Thereby, a discharge flow rate of the pump can be reduced.

{CITATION LIST}

{Patent Literature}

Patent Citation 1: JP 2009-150462 A (Page 13, FIG. 2)

{SUMMARY OF INVENTION}

{Technical Problem}

In the fluid pressure circuit as in Patent Citation 1, the head side oil chambers of the two boom cylinders join together and are connected to the accumulator. According to this, at the time of raising the boom, discharge pressure of the pump acts on a total pressure receiving area of two pistons. Thus, a thrust force at the time of raising the boom is increased. However, at the time of lowering the boom, a load of the boom is dispersed in the total pressure receiving area of the two pistons. Thus, there is a problem that efficiency of pressure accumulation into the accumulator is lowered.
The present invention has been made in view of such a problem, and an object of the present invention is to provide a fluid pressure circuit in which efficiency of pressure accumulation is high.

{Solution to Problem}

In order to solve the foregoing problem, a fluid pressure circuit according to the present invention is a fluid pressure circuit, including a plurality of drive portions connected to a single load; and an accumulator configured for accumulating pressure, wherein the drive portions include at least one first drive portion of which a return flow passage branches off and is connected to the accumulator. According to the feature of the present invention, at the time of cancelling drive of the load, a force acting from the load concentrates on the first drive portion whose number is less than the number of the drive portions that work at the time of driving the load. Thus, it is possible to accumulate pressure of a fluid in the accumulator at high pressure.
It may be preferable that the drive portions except the first drive portion include at least one second drive portion of which a return flow passage is connected to a tank. According to this preferable configuration, the load can be driven by at least the second drive portion at the time of driving the load, a returning fluid flows from the second drive portion to the tank at the time of cancelling the drive of the load, and the force acting from the load concentrates on the first drive portion. Thus, it is possible to accumulate the pressure of the fluid in the accumulator at high pressure.
It may be preferable that the fluid pressure circuit further includes a pressure booster provided between the return flow passage of the first drive portion and the accumulator. According to this preferable configuration, the accumulator can ensure high fluid pressure by the pressure booster. Thereby, it is possible to enhance freedom of sizes and combination of the drive portions.
It may be preferable that a plurality of the first drive portions are provided. According to this preferable configuration, even when a flow rate of the returning fluid per first drive portion is small, it is possible to ensure a high flow rate of the returning fluid over all the drive portions.
It may be preferable that a size of a pressure receiving surface of the first drive portion is smaller than a size of a pressure receiving surface of the second drive portion. According to this preferable configuration, it is possible to make an attachment space of the first drive portion small. Thus, attachment freedom is high.
It may be preferable that the drive portions are cylinder devices. According to this preferable configuration, it is possible to control and drive the plurality of cylinder devices with high precision.
It may be preferable that the first drive portions are smaller in number than the second drive portions. According to this preferable configuration, reaction of the load acting on the first drive portion becomes large. Thus, it is possible to accumulate the pressure of the fluid in the accumulator at higher pressure.

{BRIEF DESCRIPTION OF DRAWINGS}

FIG. 1 is an overview diagram illustrating a fluid pressure circuit according to a first embodiment of the present invention.
FIG. 2 is an overview diagram illustrating a fluid pressure circuit according to a second embodiment of the present invention.
FIG. 3 is an overview diagram illustrating a fluid pressure circuit according to a third embodiment of the present invention.
FIG. 4 is an overview diagram illustrating a fluid pressure circuit according to a fourth embodiment of the present invention.

{DESCRIPTION OF EMBODIMENTS}

Modes for implementing a fluid pressure circuit according to the present invention will be described below based on embodiments.

{First embodiment}

A fluid pressure circuit according to a first embodiment of the present invention will be described with reference to FIG. 1.
The fluid pressure circuit according to the first embodiment is to accumulate pressure of a working fluid discharged from a cylinder device of a working machine, a construction machine, a material handling machine, an automobile, an industrial machine, etc., in an accumulator, and to regenerate in a hydraulic cylinder device.
As illustrated in FIG. 1, a fluid pressure circuit 100 is mainly configured by a hydraulic pump 1, a drive source 2 that drives the hydraulic pump 1, a switching valve 3, a load 4, cylinder devices 5, 6, 7 serving as drive portions, a check valve 8, a pressure accumulation switching valve 9, an accumulator 10 serving as a hydraulic accumulator, a regeneration switching valve 11, and a tank 14. The cylinder device 7 is a first drive portion in the present invention, and the cylinder devices 5, 6 are the second drive portions in the present invention.
The switching valve 3 is connected to the hydraulic pump 1 by a flow passage 20, and connected to the tank 14 by a flow passage 21.
The three cylinder devices 5, 6, 7 are connected to the single load 4 in parallel. Since specifications of these cylinder devices 5, 6, 7 are the same as each other, it is possible to easily control and drive the load 4 with high precision.
First oil chambers 5-1, 6-1, 7-1 of the three cylinder devices 5, 6, 7 are connected to a flow passage 23 extending from the switching valve 3 in parallel. The check valve 8 is provided in a portion extending from the flow passage 23 to the first oil chamber 7-1.
A flow passage 23-1 that connects the check valve 8 and the first oil chamber 7-1 is connected to the pressure accumulation switching valve 9 by a flow passage 23-2 serving as a return flow passage.
The pressure accumulation switching valve 9 is connected to the switching valve 3 side of the cylinder devices 5, 6, 7 in the flow passage 23 by a flow passage 23-5.
Also, separately from the flow passage 23-5, a branch flow passage 23-3 is connected to the pressure accumulation switching valve 9, and the branch flow passage 23-3 is connected to the accumulator 10. Also, the accumulator 10 is connected to the flow passage 23 via a flow passage 23-4 and the regeneration switching valve 11.
Also, second oil chambers 5-2, 6-2, 7-2 of the cylinder devices 5, 6, 7 are connected to a flow passage 24 extending from the switching valve 3 in parallel.
When the switching valve 3 is placed at a raising position R, an oil discharged from the hydraulic pump 1 is supplied to the first oil chambers 5-1, 6-1, 7-1 of the cylinder devices 5, 6, 7 through the flow passages 20, 23, and oils of the second oil chambers 5-2, 6-2, 7-2 are discharged to the tank 14 through the flow passages 24, 21. Thereby, the cylinder devices 5, 6, 7 are brought into a raising action, that is, the load 4 is brought into a drive and raising state.
At the time of the raising action of the cylinder devices 5, 6, 7, the pressure accumulation switching valve 9 is placed at a position where the flow passage 23-2 and the flow passage 23-5 communicate with each other, the regeneration switching valve 11 is placed at an open position, and the flow passage 23-4 communicates with the flow passage 23.
Thereby, the oil accumulated in the accumulator 10 to be described later is regenerated in the first oil chambers 5-1, 6-1, 7-1 of the cylinder devices 5, 6, 7 through the regeneration switching valve 11. Therefore, it is possible to reduce a flow rate of the hydraulic pump 1, and to obtain an energy saving effect. For example, in a case where the hydraulic pump 1 is a swash plate type variable capacity pump as in FIG. 1, a pump swash plate may be controlled and the flow rate may be adjusted.
Meanwhile, when the switching valve 3 is placed at a lowering position D, the oil discharged from the hydraulic pump 1 is supplied to the second oil chambers 5-2, 6-2, 7-2 of the cylinder devices 5, 6, 7 through the flow passages 20, 24, and the oils of the first oil chambers 5-1, 6-1 of the cylinder devices 5, 6 are discharged to the tank 14 through the flow passages 23, 21. Thereby, the cylinder devices 5, 6, 7 are brought into a lowering action, that is, into a state where drive and raising of the load 4 is cancelled.
At the time of the lowering action of the cylinder devices 5, 6, 7, the pressure accumulation switching valve 9 is switched to provide communication between the flow passage 23-2 and the branch flow passage 23-3, the regeneration switching valve 11 is placed at a closed position, and the flow passage 23-4 does not communicate with the flow passage 23 any more.
Thereby, the oil of the first oil chamber 7-1 of the cylinder device 7 passes through the flow passages 23-1, 23-2, the pressure accumulation switching valve 9, and the branch flow passage 23-3, and pressure of the oil is accumulated in the accumulator 10.
Also, when the switching valve 3 is placed at a neutral position N, drive of the hydraulic pump 1 is stopped, the first oil chambers 5-1, 6-1 of the cylinder devices 5, 6 are connected to the tank 14 through the flow passages 23, 21, the first oil chamber 7-1 of the cylinder device 7 is connected to the tank 14 through the flow passage 23-2, the pressure accumulation switching valve 9, and the flow passages 23-5, 21, and the second oil chambers 5-2, 6-2, 7-2 of the cylinder devices 5, 6, 7 are connected to the tank 14 through the flow passages 24, 21.
When the switching valve 3 is placed at the neutral position N, the cylinder devices 5, 6, 7 hardly move. For example, after drive and raising of the load 4, and when the drive is cancelled, the switching valve 3 is switched to the neutral position N. Strictly speaking, at the neutral position N of the switching valve 3, the pressure accumulation switching valve 9 is switched to provide communication between the flow passage 23-2 and the flow passage 23-5, and a flow rate of the oil of the first oil chamber 7-1 of the cylinder device 7 is decreased by a throttle flow passage of the pressure accumulation switching valve 9. Thus, the cylinder devices 5, 6, 7 perform the lowering action extremely slowly.
In the fluid pressure circuit 100 as in FIG. 1, an area of piston heads serving as pressure receiving surfaces of the cylinder devices 5, 6 is A1, an area of a piston head serving as a pressure receiving surface of the cylinder device 7 is A2, pressure in the first oil chambers 5-1, 6-1 at the time of lowering pistons of the cylinder devices 5, 6 is P1, pressure in the first oil chamber 7-1 at the time of lowering a piston of the cylinder device 7 is P2, pressure in the second oil chambers 5-2, 6-2 at the time of raising the pistons is P1', pressure in the second oil chamber 7-2 at the time of raising the piston is P2', and a total load to the cylinder devices 5, 6, 7 is W1.
Regarding balance of forces at the time of raising the pistons, a relationship of A1×P1'×2+A2×P2'=W1 is established.
Meanwhile, at the time of lowering the pistons, the first oil chambers 5-1, 6-1 of the cylinder devices 5, 6 are connected to the tank 14. Thus, a relationship P1=0 is established, and regarding P2, a fixed load is applied by the throttle flow passage of the pressure accumulation switching valve 9. Therefore, a relationship P2>0 is established. Thus, a relationship A2×P2=W1 is established.
In such a way, at the time of raising the pistons, the pressures P1', P2' act on a total area A1×2+A2 of the piston heads. Thus, a thrust force at the time of raising the pistons is increased. Also, at the time of lowering the pistons, the total load W1 concentrates on the total area A2 of the piston heads. Thus, it is possible to accumulate the oil in the accumulator 10 at high pressure.
Also, one cylinder device 7 serving as the first drive portion utilized for pressure accumulation is provided, and two cylinder devices 5, 6 serving as the second drive portions for driving the load 4 are provided. That is, the number of the first drive portion is smaller than the number of the second drive portions. According to this, it is possible to reduce the total area of the piston heads at the time of lowering the pistons. Thus, it is possible to accumulate the oil in the accumulator 10 efficiently.
It is noted that one or three or more cylinder devices for driving the load may be provided.
Also, the cylinder device 7 is preferably arranged at a position where the load 4 can be supported in a well-balanced manner at the time of lowering the pistons, for example, may be arranged immediately below the vicinity of a gravity center of the load 4.

{Second embodiment}

Next, a fluid pressure circuit according to a second embodiment of the present invention will be described with reference to FIG. 2. It is noted that a description of the same and duplicated configurations as the first embodiment will be omitted.
In a fluid pressure circuit 200 illustrated in FIG. 2, a flow dividing valve 29 is provided between a flow passage 223-2 and a flow passage 223-5. The flow dividing valve 29 and an accumulator 210 are connected to each other by a branch flow passage 223-3. A pressure booster 215 is provided in this branch flow passage 223-3.
At the time of a lowering action of cylinder devices 25, 26, 27, an oil of a first oil chamber 27-1 of the cylinder device 27 flows into the flow dividing valve 29 through flow passages 223-1, 223-2. The oil flowing into the flow dividing valve 29 is divided into the flow passage 223-5 and the branch flow passage 223-3.
The oil flowing through the branch flow passage 223-3 is introduced to the pressure booster 215. The pressure booster 215 is a cylinder device including, for example, a stepped cylindrical case having a large diameter portion and a small diameter portion, and a piston having a large diameter portion and a small diameter portion, in which the piston is moved by inputting the oil from the first oil chamber 27-1 into an input chamber on the large diameter portion side, pressure of an oil of an output chamber on the small diameter portion side is intensified, and the oil is fed out.
The oil whose pressure is intensified by the pressure booster 215 is accumulated in the accumulator 210.
In such a way, the accumulator 210 can ensure high accumulation pressure by the pressure booster 215. Thus, it is possible to enhance freedom of dimeters of piston heads of the cylinder devices 25, 26, 27 and combination of those.
In detail, in a case where the pressure booster 215 is not provided, in order to accumulate the pressure of the oil in the accumulator 210 at high pressure, there is a need to make the diameter of the piston head of the cylinder device 27 small. When making the diameter of the piston head of the cylinder device 27 small, a relationship A1×P1'×2+A2×P2'<W1 is established, and in order to raise the piston, there is a need to increase a flow rate of a hydraulic pump 1.
Meanwhile, in order to increase a thrust force at the time of raising the piston, there is a need to make the diameter of the piston head of the cylinder device 27 large. When making the diameter of the piston head of the cylinder device 27 large, there is a defect that P2=W1/A2 becomes small and efficiency of pressure accumulation into the accumulator 210 is lowered. Therefore, there is a limit to design freedom of the diameter of the piston head that meets both pressure accumulation and drive of a load.
In the fluid pressure circuit 200 of the second embodiment, the pressure booster 215 is provided. Thus, even when making the diameter of the piston head of the cylinder device 27 for pressure accumulation large and improving the thrust force at the time of a raising action of the cylinder device 27, the accumulator 210 can accumulate high fluid pressure. That is, the freedom of the dimeters of the piston heads of the cylinder devices 25, 26, 27 and combination of those is high.
It is noted that in the second embodiment, the mode in which the pressure booster 215 utilizes a returning oil of the cylinder device 27 for pressure accumulation as primary pressure is shown as an example. However, the present invention is not limited to this, but the returning oil of the cylinder device 27 for pressure accumulation may be introduced into an oil chamber, and the returning oil may be pressurized by a piston activated by other drive source, and output to an accumulator as secondary pressure.
Also, the pressure booster is not limited to the hydraulic cylinder device, but may be a cylinder device to be driven by a fluid other than hydraulic pressure, or may be a cylinder device to be driven by a motor.

{Third embodiment}

Next, a fluid pressure circuit according to a third embodiment of the present invention will be described with reference to FIG. 3. It is noted that a description of the same and duplicated configurations as the second embodiment will be omitted.
In a fluid pressure circuit 300 illustrated in FIG. 3, piston diameters serving as pressure receiving surfaces are different between cylinder devices 35, 36, and a cylinder device 37. In detail, a piston diameter D1 of the single cylinder device 37 is smaller than each of piston diameters D2, D2 of the cylinder devices 35, 36.
According to this, at the time of lowering the cylinder devices 35, 36, 37, it is possible to efficiently increase pressure of an oil flowing from a first oil chamber 37-1 of the cylinder device 37 toward an accumulator 310.
Also, since it is possible to compactify the cylinder device 37, attachment freedom of the cylinder device 37 is high.
Also, it is possible to make a returning oil from the first oil chamber 37-1 of the cylinder device 37 extremely high pressure by intensifying the pressure by a pressure booster 315 in addition to the small piston diameter D1 of the cylinder device 37. Thus, it is possible to accumulate the oil of high pressure in the accumulator 310. According to this, it is possible to regenerate by using the accumulated oil of high pressure by the small accumulator 310.
It is noted that in the third embodiment, the mode in which the cylinder devices 35, 36, 37 are installed in the fluid pressure circuit 300 in advance is shown as an example. However, the cylinder device 37 may be additionally installed in the existing fluid pressure circuit in which the cylinder devices 35, 36 are provided. According to this, by additionally installing the compact cylinder device 37 in the existing fluid pressure circuit, it is possible to increase the pressure of the oil accumulated in the accumulator 310.
Also, this third embodiment can also be applied to the first embodiment. For example, instead of the cylinder device 7 of the first embodiment, the cylinder device 37 and the pressure booster 315 of the third embodiment may be applied.

{Fourth embodiment}

Next, a fluid pressure circuit according to a fourth embodiment of the present invention will be described with reference to FIG. 4. It is noted that a description of the same and duplicated configurations as the second embodiment will be omitted.
In a fluid pressure circuit 400 illustrated in FIG. 4, four cylinder devices 45, 46, 47, 48 are connected to a load 44.
The cylinder device 48 has the same specification as and is arranged in parallel with the cylinder devices 45, 46, 47. A first oil chamber 48-1 of this cylinder device 48 is connected to a flow passage 43 via a flow passage 423-1' and a check valve 8'.
The flow passage 423-1' is connected to a flow passage 423-2 extending from the flow passage 423-1 of the cylinder device 47 to a flow dividing valve 49. That is, the first oil chamber 48-1 of the cylinder device 48 is connected to an accumulator 410 together with a first oil chamber 47-1 of the cylinder device 47.
According to this, it is possible to have the accumulator 410 accumulate an oil by using the two cylinder devices 47, 48 for pressure accumulation. Thus, even when a flow rate of a returning oil of each of the cylinder devices 47, 48 is a small amount, it is possible to ensure a high flow rate of returning oils in total.
It is noted that the number of the cylinder devices for pressure accumulation may be three or more.
Also, this fourth embodiment can also be applied to the first embodiment and the third embodiment. For example, the cylinder device 48 of the fourth embodiment may be added to the fluid pressure circuit 100 of the first embodiment and the fluid pressure circuit 300 of the third embodiment.
Also, in the fourth embodiment, the mode in which the cylinder devices 47, 48 for pressure accumulation have the same specification is shown as an example. However, the diameters of the piston heads of the plurality of cylinder devices for pressure accumulation may be different from each other. In this case, it is preferable that pressure introduced from each of the cylinder devices for pressure accumulation to the accumulator is adjusted to be the same by a pressure adjusting valve, etc.
The embodiments of the present invention are described above based on the drawings. However, specific configurations are not limited to these embodiments and the present invention includes changes and additions within a range not departing from the scope of the present invention.
For example, in the first to fourth embodiments described above, the mode in which the cylinder device is utilized as the drive portion is shown as an example. However, a change may be freely made with an actuator that utilizes a fluid.
Also, in the first to fourth embodiments described above, the mode in which the first drive portion and the second drive portions drive and raise the load together is shown as an example. However, as long as at least the second drive portions drive and raise the load, the first drive portion is not required to contribute to drive and raising of the load.
Also, in the first to third embodiments described above, the mode in which the number of the first drive portion is smaller than the number of the second drive portions is shown as an example, and in the fourth embodiment, the mode in which the number of the first drive portions is the same as the number of the second drive portions is shown as an example. However, the number of the first drive portions may be more than the number of the second drive portions, and it is only required that the number of drive portions that contribute to pressure accumulation is smaller than the number of drive portions that contribute to drive and raising of the load.
Also, in the first to fourth embodiments described above, the fluid pressure circuit is described as a hydraulic circuit in which an oil is pressure-fed. However, the present invention is not limited to this but the working fluid may be a fluid other than the oil, and a fluid to be applied may be appropriately changed.
Also, in the first to fourth embodiments described above, the mode in which the first drive portion is connected to the accumulator and the second drive portions are connected to the tank and not connected to the accumulator is shown as an example. However, the return flow passages of all the drive portions may be connected to the accumulator. For example, a flow passage switching valve may be provided between each of the return flow passages and the accumulator, and the accumulator or the tank may be appropriately selected as a connection destination of each of the return flow passages.

{REFERENCE SIGNS LIST}

1: Hydraulic pump
3: Switching valve
4: Load
5, 6: Cylinder device (second drive portion)
5-1, 6-1: First oil chamber
5-2, 6-2: Second oil chamber
7: Cylinder device (first drive portion)
7-1: First oil chamber
7-2: Second oil chamber
8, 8': Check valve
9: Pressure accumulation switching valve
10: Accumulator
11: Regeneration switching valve
14: Tank
23-2, 23-5: Flow passage (return flow passage)
100: Fluid pressure circuit

Claims

A fluid pressure circuit, comprising:
a plurality of drive portions connected to a single load; and

an accumulator configured for accumulating pressure,

wherein the drive portions include at least one first drive portion of which a return flow passage branches off and is connected to the accumulator.
The fluid pressure circuit according to claim 1,
wherein the drive portions except the first drive portion include at least one second drive portion of which a return flow passage is connected to a tank.
The fluid pressure circuit according to claim 2, further comprising
a pressure booster provided between the return flow passage of the first drive portion and the accumulator.
The fluid pressure circuit according to claim 3,
wherein a plurality of the first drive portions are provided.
The fluid pressure circuit according to claim 2,
wherein a size of a pressure receiving surface of the first drive portion is smaller than a size of a pressure receiving surface of the second drive portion.
The fluid pressure circuit according to claim 1,
wherein the drive portions are cylinder devices.
The fluid pressure circuit according to claim 2,
wherein the first drive portions are smaller in number than the second drive portions.