Fluid pressure drive unit

Abstract

This fluid pressure drive unit (100) is provided with: a hydraulic cylinder (10); a bidirectional pump (20) which discharges hydraulic oil from one of a first pump port (20A) and a second pump port (20B) in accordance with the rotation direction of a drive shaft; a bottom-side passage (1) which connects a bottom-side chamber (14) of the hydraulic cylinder (10) and the first pump port (20A); a rod-side passage (2) which connects a rod-side chamber (15) of the hydraulic cylinder (10) and the second pump port (20B); a first communication passage (1C) that is branched from the bottom-side passage (1) and can communicate with the hydraulic cylinder (50); a first solenoid valve (31) provided in the first communication passage (1C); and a second solenoid valve (32) provided closer to the hydraulic cylinder (10) than a branching point of the bottom-side passage (1), the first communication passage (1C) being branched from the bottom-side passage (1) at the branching point.

Description

Fluid pressure drive unit

[0001] The present invention relates to a fluid pressure drive unit.

[0002] Japanese Unexamined Patent Publication No. 2021-152393 discloses a hydraulic control device configured to drive a fluid pressure cylinder by a hydraulic pump (bi-directional pump).

[0003] In the hydraulic control device described in Patent Document 1, one hydraulic pump (bi-directional pump) is used for one actuator. For this reason, the number of hydraulic pumps (bi-directional pumps) increases, leading to an increase in cost.

[0004] An object of the present invention is to implement a fluid pressure drive unit capable of driving a plurality of actuators at low cost.

[0005] According to an aspect of the present invention, there is provided: a fluid pressure cylinder; a bi-directional pump that discharges working fluid from one of a first pump port and a second pump port in accordance with the rotation direction of a drive shaft, and supplies the working fluid to the fluid pressure cylinder; a first passage that connects a first pressure chamber of the fluid pressure cylinder and the first pump port of the bi-directional pump; a second passage that connects a second pressure chamber of the fluid pressure cylinder and the second pump port of the bi-directional pump; a first communication passage branched from the first passage and capable of communicating with an external fluid pressure actuator; a first switching unit provided in the first communication passage and configured to control the flow of working fluid in the first communication passage; and a second switching unit provided closer to the fluid pressure cylinder side than a branch point with the first communication passage in the first passage, and configured to control the flow of working fluid in the first passage.

[0006] According to another aspect of the present invention, the fluid pressure drive unit includes a bidirectional pump that discharges working fluid from one of a first pump port and a second pump port depending on the rotation direction of the drive shaft; a first passage connected to the first pump port of the bidirectional pump and connectable to a first fluid pressure cylinder; a second passage connected to the second pump port of the bidirectional pump and connectable to the first fluid pressure cylinder; a first connecting passage branching off from the first passage and connectable to the second fluid pressure cylinder; a first switching unit provided in the first connecting passage for controlling the flow of fluid in the second fluid pressure cylinder of the first connecting passage; and a second switching unit provided on the side of the first passage away from the bidirectional pump at the branching point with the first connecting passage for controlling the flow of fluid in the second fluid pressure cylinder of the first passage.

[0007] In this configuration, the second fluid pressure cylinder discharged from the pump can be supplied to the second switching unit via a branch from the first passage and to the first switching unit via a first connecting passage, thereby enabling the first and second fluid pressure cylinders to be driven.

[0008] This is a front view of a fluid pressure drive unit according to an embodiment of the present invention. This is a top view of a fluid pressure drive unit according to an embodiment of the present invention. This is a hydraulic circuit diagram of a fluid pressure drive unit according to an embodiment of the present invention. This is a hydraulic circuit diagram when two single-acting hydraulic cylinders are connected to a fluid pressure drive unit according to an embodiment of the present invention. This is a hydraulic circuit diagram of a fluid pressure drive unit according to a modified example. This is a hydraulic circuit diagram of a fluid pressure drive unit according to a modified example.

[0009] Embodiments of the present invention will be described below with reference to the drawings.

[0010] First, the configuration of the fluid pressure drive unit 100 according to an embodiment of the present invention will be described with reference to Figures 1 and 2.

[0011] The fluid pressure drive unit 100 includes a hydraulic cylinder 10 which extends and retracts by supplying and discharging hydraulic fluid as a working fluid, a pump 20 which is a bidirectional pump having a pair of pump ports and selectively discharging hydraulic fluid from one of the pair of pump ports, an electric motor M which drives the pump 20, a tank T which stores hydraulic fluid, a first valve unit 30 which controls the flow of hydraulic fluid to the hydraulic cylinder 10 and a hydraulic cylinder 50 (see Figure 3, etc.) which is a fluid pressure actuator provided externally (separate from the fluid pressure drive unit 100) as a fluid pressure actuator, and a second valve unit 40 which controls the flow of hydraulic fluid between the first valve unit 30 and the pump 20. The fluid pressure drive unit 100 is constructed by integrating the hydraulic cylinder 10, the pump 20, the electric motor M, the tank T, the first valve unit 30, and the second valve unit 40 by bolting them together. The hydraulic cylinder 10 corresponds to the first fluid pressure cylinder described in the claims, and the hydraulic cylinder 50 corresponds to the second fluid pressure cylinder described in the claims.

[0012] Next, a more specific configuration of the fluid pressure drive unit 100 will be described with reference to Figures 1 to 3. Figure 3 is a hydraulic circuit diagram of the fluid pressure drive unit 100.

[0013] As shown in Figure 3, the hydraulic cylinder 10 includes a cylindrical cylinder tube 11, a piston rod 12 inserted into the cylinder tube 11, and a piston 13 provided at the end of the piston rod 12 that slides along the inner circumferential surface of the cylinder tube 11.

[0014] The inside of the cylinder tube 11 is divided by the piston 13 into a bottom chamber 14 and a rod chamber 15. The bottom chamber 14 and the rod chamber 15 are filled with hydraulic fluid.

[0015] In the hydraulic cylinder 10, hydraulic fluid is supplied to the bottom chamber 14 and discharged from the rod chamber 15, causing the piston rod 12 to move in the extension direction, thus performing an extension operation. In the hydraulic cylinder 10, hydraulic fluid is supplied to the rod chamber 15 and discharged from the bottom chamber 14, causing the piston rod 12 to move in the contraction direction, thus performing a contraction operation.

[0016] Pump 20 is, for example, a gear pump and has a pair of first pump ports 20A and second pump ports 20B. Pump 20 is installed in the first valve block 21 (see Figures 1 and 2) together with the second valve unit 40. The drive shaft of pump 20 is connected to the rotating shaft of an electric motor M and is driven by the rotation of the rotating shaft of the electric motor M. When the rotating shaft of the electric motor M is driven in the forward direction, pump 20 discharges the hydraulic fluid drawn in from the second pump port 20B from the first pump port 20A, and when the rotating shaft of the electric motor M is driven in the reverse direction, pump 20 discharges the hydraulic fluid drawn in from the first pump port 20A from the second pump port 20B. In this way, the discharge direction of the hydraulic fluid discharged from pump 20 is switched according to the rotation direction of the electric motor M (the rotation direction of the drive shaft of pump 20).

[0017] As shown in Figure 3, the first pump port 20A of the pump 20 is connected to the bottom chamber 14, which serves as the first pressure chamber of the hydraulic cylinder 10, through the bottom passage 1, which serves as the first passage. The second pump port 20B of the pump 20 is connected to the rod chamber 15, which serves as the second pressure chamber of the hydraulic cylinder 10, through the rod passage 2, which serves as the second passage.

[0018] As shown in Figure 3, the first valve unit 30 includes a first communication passage 1C that branches off from the bottom passage 1 and can communicate with an external hydraulic actuator, a first solenoid valve 31 provided in the first communication passage 1C as a first switching unit that controls the flow of hydraulic fluid in the first communication passage 1C, a second solenoid valve 32 provided on the hydraulic cylinder 10 side (opposite pump 20 side) of the branching point between the bottom passage 1 and the first communication passage 1C as a second switching unit that controls the flow of hydraulic fluid in the bottom passage 1, and a second solenoid valve 32 that branches off from the rod-side passage 2 and can communicate with an external hydraulic actuator. The system includes a double passage 2C, a third solenoid valve 33 provided in the second passage 2C as a third switching unit that controls the flow of hydraulic fluid in the second passage 2C, a fourth solenoid valve 34 provided on the hydraulic cylinder 10 side of the branching point of the second passage 2C in the rod-side passage 2 as a fourth switching unit that controls the flow of hydraulic fluid through the rod-side passage 2, and a second valve block 35 (see Figures 1 and 2) to which the first to fourth solenoid valves 31 to 34 are attached, and which has the first and second passages 1C and 2C, the bottom-side passage 1 and a part of the rod-side passage 2 formed inside.

[0019] The first to fourth solenoid valves 31 to 34 in this embodiment are composed of two-port, two-position solenoid switching valves. As shown in Figures 1 and 2, the second valve block 35 is provided so as to be sandwiched between the hydraulic cylinder 10 and the first valve block 21, and is connected to the hydraulic cylinder 10 and the first valve block 21, respectively. In this embodiment, the second valve block 35 is detachably provided between the hydraulic cylinder 10 and the pump 20. Therefore, the hydraulic cylinder 10 and the pump 20 can be directly connected even without the second valve block 35.

[0020] The side surface of the second valve block 35 is provided with a first port 36 through which the first communication passage 1C opens, and a second port 37 through which the second communication passage 2C opens (see Figure 2, etc.). In this embodiment, the first port 36 and the second port 37 open on opposite sides of the second valve block 35, but the first port 36 and the second port 37 may be provided to open on the same side surface.

[0021] The first port 36 and the second port 37 are used to connect piping for supplying hydraulic fluid to an external fluid pressure actuator, respectively. In this embodiment, when the first port 36 and the second port 37 are not used (when the hydraulic cylinder 50 is not connected), the first port 36 and the second port 37 are closed by plugs (see Figures 1 and 2).

[0022] As shown in Figure 3, the second valve unit 40 includes a first operate check valve 41 provided in the bottom passage 1 to block the flow of hydraulic fluid from the bottom chamber 14 to the pump 20, a second operate check valve 42 provided in the rod passage 2 to block the flow of hydraulic fluid from the rod chamber 15 to the pump 20, and a switching valve 43 that controls communication between the tank T and the bottom passage 1 and between the tank T and the rod passage 2.

[0023] The first operate check valve 41 opens when the pressure on the upstream side of the second operate check valve 42 increases, or in other words, when the pressure of the hydraulic fluid discharged from the second pump port 20B is guided through the pilot passage 41A. When the first operate check valve 41 is open, the flow of hydraulic fluid from the bottom side chamber 14 to the pump 20 is permitted. Similarly, the second operate check valve 42 opens when the pressure on the upstream side of the first operate check valve 41 increases, or in other words, when the pressure of the hydraulic fluid discharged from the first pump port 20A is guided through the pilot passage 42A. When the first operate check valve 41 is open, the flow of hydraulic fluid from the rod side chamber 15 to the pump 20 is permitted.

[0024] Furthermore, a first relief passage 1A, which communicates with the tank T, is connected between the first operate check valve 41 and the second solenoid valve 32 in the bottom passage 1. The first relief passage 1A is provided with a first relief valve 44 that opens when the pressure downstream of the first operate check valve 41 in the bottom passage 1 reaches a predetermined relief pressure, releasing the pressure to the tank T. A second relief passage 2A, which communicates with the tank T, is connected between the second operate check valve 42 and the fourth solenoid valve 34 in the rod passage 2. The second relief passage 2A is provided with a second relief valve 45 that opens when the pressure downstream of the second operate check valve 42 in the rod passage 2 reaches a predetermined relief pressure, releasing the pressure to the tank T.

[0025] A relief passage 1B communicating with the tank T is connected between the first operate check valve 41 and the pump 20 in the bottom-side passage 1, and a relief valve 46 is provided in the relief passage 1B. A relief passage 2B communicating with the tank T is connected between the second operate check valve 42 and the pump 20 in the rod-side passage 2, and a relief valve 47 is provided in the relief passage 2B. The relief valves 46 and 47, located upstream (on the pump 20 side) of the first operate check valve 41 and the second operate check valve 42, limit the pressure discharged from the pump 20.

[0026] As shown in Figure 3, the switching valve 43 is connected to a first sub-passage 3 which is connected to the bottom-side passage 1 between the first pump port 20A and the first operate check valve 41, a second sub-passage 4 which is connected to the rod-side passage 2 which is connected to the second pump port 20B and the second operate check valve 42, and a tank passage 5 which communicates with the tank T.

[0027] The switching valve 43 has a neutral position A that blocks communication between the tank passage 5 and the first sub-passage 3 and the second sub-passage 4, a first position B that connects the first sub-passage 3 and the tank passage 5 and blocks communication between the second sub-passage 4 and the tank passage 5, and a second position C that connects the second sub-passage 4 and the tank passage 5 and blocks communication between the first sub-passage 3 and the tank passage 5.

[0028] The switching valve 43 is held in the neutral position A by the biasing force of a pair of biasing members, springs 43A and 43B.

[0029] The switching valve 43 is switched to the second position C when the pressure of the hydraulic fluid discharged from the first pump port 20A of the pump 20 (hydraulic pressure in the bottom-side passage 1) is introduced as pilot pressure, causing the spool to move against the other spring 43B. The switching valve 43 is also switched to the first position B when the pressure of the hydraulic fluid discharged from the second pump port 20B of the pump 20 (hydraulic pressure in the rod-side passage 2) is introduced as pilot pressure, causing the spool (not shown) to move against the other spring 43A.

[0030] Next, the operation of the fluid pressure drive unit 100 will be explained in detail.

[0031] When the electric motor M does not rotate and the pump 20 stops operating, all of the first to fourth solenoid valves 31 to 34 are closed. As a result, the hydraulic cylinders 10 and 50 remain in a load-holding state, holding the load without operating.

[0032] Next, the case in which the hydraulic cylinder 10 is extended will be described. When the hydraulic cylinder 10 is extended, the second solenoid valve 32 and the fourth solenoid valve 34 are opened, and the first solenoid valve 31 and the third solenoid valve 33 are closed, and the electric motor M is driven in the forward direction.

[0033] When the electric motor M is driven in the forward direction, the pump 20 draws in hydraulic fluid from the second pump port 20B and discharges it from the first pump port 20A. The hydraulic fluid discharged from the first pump port 20A of the pump 20 is guided to the bottom side passage 1 and supplied to the bottom side chamber 14 of the hydraulic cylinder 10 through the first operate check valve 41 and the second solenoid valve 32. In addition, the pressure of the hydraulic fluid discharged from the first pump port 20A is guided as pilot pressure to the second operate check valve 42 through the pilot passage 42A, causing the second operate check valve 42 to open. As a result, the hydraulic fluid discharged from the rod side chamber 15 of the hydraulic cylinder 10 is guided to the rod side passage 2 and drawn into the second pump port 20B of the pump 20 through the fourth solenoid valve 34 and the second operate check valve 42. In this way, the hydraulic cylinder 10 extends as the pump 20 draws in the hydraulic fluid discharged from the rod side chamber 15 through the second pump port 20B and discharges it from the first pump port 20A to supply it to the bottom side chamber 14.

[0034] Furthermore, the hydraulic fluid discharged from the first pump port 20A of the pump 20 is guided to the switching valve 43 as pilot pressure, causing the switching valve 43 to switch to the second position C. In the second position C, the rod-side passage 2 communicates with the tank T through the second sub-passage 4, the switching valve 43, and the tank passage 5. As a result, when the hydraulic cylinder 10 extends, hydraulic fluid equivalent to the volume of the piston rod 12 retracting from the cylinder tube 11 is drawn from the tank T into the second pump port 20B through the tank passage 5, the switching valve 43, the second sub-passage 4, and the rod-side passage 2, thereby compensating for the volume difference between the bottom chamber 14 and the rod-side chamber 15.

[0035] Next, the case in which the hydraulic cylinder 10 is retracted will be described. When the hydraulic cylinder 10 is retracted, the second solenoid valve 32 and the fourth solenoid valve 34 are opened, and the first solenoid valve 31 and the third solenoid valve 33 are closed, and the electric motor M is driven in reverse.

[0036] When the electric motor M is driven in reverse, the pump 20 draws in hydraulic fluid from the first pump port 20A and discharges it from the second pump port 20B. The hydraulic fluid discharged from the second pump port 20B of the pump 20 is guided to the rod-side passage 2 and supplied to the rod-side chamber 15 of the hydraulic cylinder 10 through the second operate check valve 42 and the fourth solenoid valve 34. In addition, the pressure of the hydraulic fluid discharged from the second pump port 20B is guided as pilot pressure to the first operate check valve 41 through the pilot passage 41A, causing the first operate check valve 41 to open. As a result, the hydraulic fluid discharged from the bottom-side chamber 14 of the hydraulic cylinder 10 is guided to the bottom-side passage 1 and drawn into the first pump port 20A of the pump 20 through the second solenoid valve 32 and the first operate check valve 41. In this way, the pump 20 draws in the hydraulic fluid discharged from the bottom chamber 14 through the first pump port 20A and discharges it through the second pump port 20B to supply it to the rod chamber 15, causing the hydraulic cylinder 10 to contract.

[0037] Furthermore, the hydraulic fluid discharged from the second pump port 20B of the pump 20 is guided to the switching valve 43 as pilot pressure, causing the switching valve 43 to switch to the first position B. In the first position B, the bottom passage 1 communicates with the tank T through the first sub-passage 3, the switching valve 43, and the tank passage 5. As a result, when the hydraulic cylinder 10 retracts, the hydraulic fluid equivalent to the volume of the piston rod 12 entering the cylinder tube 11 is discharged from the bottom chamber 14 to the tank T through the first sub-passage 3, the switching valve 43, and the tank passage 5, thereby compensating for the volume difference between the rod chamber 15 and the bottom chamber 14.

[0038] Next, we will describe the case in which the hydraulic cylinder 50 connected to the first port 36 and the second port 37 is operated. In the example shown in Figure 3, the first port 36 is connected to the bottom side chamber 51 of the hydraulic cylinder 50, and the second port 37 is connected to the rod side chamber 52 of the hydraulic cylinder 50.

[0039] When extending the hydraulic cylinder 50, the first solenoid valve 31 and the third solenoid valve 33 are opened, and the second solenoid valve 32 and the fourth solenoid valve 34 are closed, and the electric motor M is driven in the forward direction. At this time, the connection state of the hydraulic circuit is the same as when extending the hydraulic cylinder 10. For this reason, the explanation of the operation of each valve in the second valve unit 40 when the hydraulic cylinder 50 is extended is omitted.

[0040] Furthermore, when the hydraulic cylinder 50 is retracted, the first solenoid valve 31 and the third solenoid valve 33 are opened, and the second solenoid valve 32 and the fourth solenoid valve 34 are closed, and the electric motor M is driven in reverse. At this time, the connection state of the hydraulic circuit is the same as when the hydraulic cylinder 10 is retracted. For this reason, the explanation of the operation of each valve in the second valve unit 40 when the hydraulic cylinder 50 is retracted is omitted.

[0041] As described above, the fluid pressure drive unit 100 of this embodiment is equipped with a first port 36 and a second port 37 for supplying hydraulic fluid to an external fluid pressure actuator, so that a single bidirectional pump (pump 20) can drive multiple hydraulic actuators (hydraulic cylinders 10, 50).

[0042] Furthermore, the fluid pressure drive unit 100 is configured as a single unit by integrating the hydraulic cylinder 10, pump 20, tank T, electric motor M, first valve unit 30, and second valve unit 40 by bolting them together. This eliminates the need for piping and other components.

[0043] Furthermore, in the fluid pressure drive unit 100, the second valve block 35 is detachably provided between the hydraulic cylinder 10 and the pump 20. This makes it possible to operate multiple fluid pressure actuators simply by adding the first valve unit 30 to an existing fluid pressure drive unit that does not have the first valve unit 30.

[0044] In the example shown in FIG. 3, the description has been given taking, as an example, a case where a double-acting hydraulic cylinder is connected to the first port 36 and the second port 37. However, as shown in FIG. 4, single-acting hydraulic cylinders 60 and 61 may be connected to the first port 36 and the second port 37.

[0045] Herein, an operation when a single-acting hydraulic cylinder 60 is connected to the first port 36 will be briefly described.

[0046] When driving the hydraulic cylinder 60, the first solenoid valve 31 is opened, the second solenoid valve 32, the third solenoid valve 33, and the fourth solenoid valve 34 are closed, and the electric motor M is driven to rotate forward.

[0047] When the electric motor M is driven to rotate forward, the pump 20 sucks hydraulic fluid from the second pump port 20B and discharges the hydraulic fluid from the first pump port 20A. The hydraulic fluid discharged from the first pump port 20A of the pump 20 is guided to the bottom-side passage 1, and is supplied to the bottom-side chamber 60a of the hydraulic cylinder 60 through the first pilot operated check valve 41, the first communication passage 1C, the first solenoid valve 31, and the first port 36.

[0048] When the hydraulic cylinder 60 is driven to extend, since the hydraulic cylinder 60 is of the single-acting type, no hydraulic fluid is discharged from the hydraulic cylinder 60, and no hydraulic fluid is supplied from the hydraulic cylinder 60 to the rod-side passage 2. However, the hydraulic fluid discharged from the first pump port 20A of the pump 20 is guided to the switching valve 43 as a pilot pressure, and the switching valve 43 is switched to the second position C. Therefore, when the pump 20 is driven to rotate forward, the hydraulic fluid in the tank T passes through the tank passage 5, the switching valve 43, the second sub-passage 4, and the rod-side passage 2, and is sucked from the second pump port 20B of the pump 20. In this way, the pump 20 sucks the hydraulic fluid in the tank T from the second pump port 20B, discharges the hydraulic fluid from the first pump port 20A, and supplies the hydraulic fluid to the bottom-side chamber 60a, whereby the hydraulic cylinder 60 extends.

[0049] When contracting the hydraulic cylinder 60, the first solenoid valve 31 is opened, the second solenoid valve 32, the third solenoid valve 33, and the fourth solenoid valve 34 are closed, and the electric motor M is driven to rotate in reverse.

[0050] When the electric motor M is driven in reverse, the pump 20 draws in hydraulic fluid from the first pump port 20A and discharges it from the second pump port 20B. At this time, since the third solenoid valve 33 and the fourth solenoid valve 34 are closed, no hydraulic fluid is supplied to the hydraulic cylinders 10 and 61, and the pressure in the rod-side passage 2 rises. When the pressure of the hydraulic fluid in the rod-side passage 2 rises further and exceeds the set pressure of the relief valve 47, the relief valve 47 opens, and the hydraulic fluid in the rod-side passage 2 is discharged into the tank T.

[0051] Furthermore, the hydraulic fluid discharged from the second pump port 20B (hydraulic fluid in the rod-side passage 2) is guided to the first operate check valve 41 through the pilot passage 41A, causing the first operate check valve 41 to open.

[0052] Therefore, when the electric motor M is driven in reverse, the hydraulic fluid in the bottom chamber 60a of the hydraulic cylinder 60 is discharged to the tank T through the first port 36, the first communication passage 1C, the first solenoid valve 31, the bottom passage 1, the first operate check valve 41, the pump 20, the rod passage 2, the relief passage 2B, and the relief valve 47. As a result, the hydraulic cylinder 60 contracts.

[0053] The operation of the hydraulic cylinder 61 is the same as that of the hydraulic cylinder 60, so a detailed explanation will be omitted. However, to briefly explain, when extending the hydraulic cylinder 61, the third solenoid valve 33 should be opened and the electric motor M driven in reverse. When retracting the hydraulic cylinder 61, the third solenoid valve 33 should be opened and the electric motor M driven in forward.

[0054] Thus, with the fluid pressure drive unit 100, even if single-acting hydraulic cylinders 60 and 61 are connected to the first port 36 and the second port 37, they can be driven.

[0055] In the embodiments described above, the fluid pressure drive unit 100 was described in a form in which the hydraulic cylinder 10, pump 20, electric motor M, tank T, first valve unit 30, and second valve unit 40 are integrated into a single unit by bolting or the like. However, the fluid pressure drive unit may be unitized without including the hydraulic cylinder 10. In other words, the fluid pressure drive unit may have a configuration in which the pump 20, electric motor M, tank T, first valve unit 30, and second valve unit 40 are integrated into a single unit by bolting or the like. In this case, the hydraulic cylinder 10 is connected to this unitized configuration for use.

[0056] In the above embodiment, the case in which the first valve unit 30 has first to fourth solenoid valves 31 to 34 was described as an example, but it is not limited to this. For example, as shown in Figure 5, two three-port, two-position solenoid valves 131 and 133 may be provided instead of the first to fourth solenoid valves 31 to 34. Below, a fluid pressure driven unit 200 according to the modified example shown in Figure 5 will be described in detail.

[0057] The fluid pressure drive unit 200 in this modified example differs from the fluid pressure drive unit 100 in that the first solenoid valve 31 and the second solenoid valve 32 in the above embodiment are composed of a single solenoid valve 131, and the third solenoid valve 33 and the fourth solenoid valve 34 are composed of a single solenoid valve 133. In the following, only this difference will be explained, and identical components will be given the same numbering and their explanations will be omitted.

[0058] The solenoid valve 131 is configured, for example, as a spool-type two-position solenoid valve. The solenoid valve 131 has a first position D that connects the passage downstream of the first operate check valve 41 in the bottom-side passage 1 (hereinafter, the passage between the first operate check valve 41 and the solenoid valve 131 in the bottom-side passage 1 is referred to as "passage 1a") to the bottom-side chamber 14 and blocks communication between the first connecting passage 1C and passage 1a, and a second position E that blocks communication between passage 1a and the bottom-side chamber 14 and connects the first connecting passage 1C and passage 1a.

[0059] The solenoid valve 133 is, for example, a spool-type two-position solenoid valve. The solenoid valve 133 has a first position F that connects the passage downstream of the second operate check valve 42 in the rod-side passage 2 (hereinafter, the passage between the second operate check valve 42 and the solenoid valve 133 in the rod-side passage 2 is referred to as "passage 2a") to the rod-side chamber 15 and blocks communication between the second communication passage 2C and passage 2a, and a second position G that blocks communication between passage 2a and the rod-side chamber 15 and connects the second communication passage 2C and passage 2a.

[0060] In this modified example, in the fluid pressure drive unit 200, a land (not shown) that controls the communication between passage 1a and the first connecting passage 1C in the spool (not shown) of the solenoid valve 131 corresponds to the "first switching section" in the claims, and a land (not shown) that controls the communication between passage 1a and the bottom side chamber 14 corresponds to the "second switching section" in the claims. Furthermore, the region in which the flow of hydraulic fluid flowing in from the port to which passage 1a of the solenoid valve 131 is connected splits into a flow toward the first connecting passage 1C and a flow toward the bottom side chamber 14, specifically the region near the space between the two lands in the spool of the solenoid valve 131, corresponds to the "branching point between the first passage and the first connecting passage" in the claims. Furthermore, a land (not shown) in the spool (not shown) of the solenoid valve 133 that controls communication between passage 2a and the second connecting passage 2C corresponds to the "third switching section" in the claims, and a land (not shown) that controls communication between passage 2a and the rod side chamber 15 corresponds to the "fourth switching section" in the claims. Moreover, the region in which the flow of hydraulic fluid flowing in from the port to which passage 2a of the solenoid valve 133 is connected splits into a flow toward the second connecting passage 2C and a flow toward the rod side chamber 15, specifically the region near the space between the two lands in the spool of the solenoid valve 133, corresponds to the "branching point between the second passage and the second connecting passage" in the claims.

[0061] Next, the operation of the fluid pressure drive unit 200 will be described.

[0062] When the electric motor M does not rotate and the pump 20 stops operating, the first operate check valve 41 and the second operate check valve 42 are closed. Therefore, regardless of the position of the solenoid valves 131 and 133, the hydraulic cylinder 10 remains in a load-holding state, maintaining the load without operating.

[0063] Next, we will explain the case in which the hydraulic cylinder 10 is extended. When extending the hydraulic cylinder 10, the solenoid valve 131 is set to the first position D, and the solenoid valve 133 is set to the first position F, and the electric motor M is driven in the forward direction. The connection state of the hydraulic circuit at this time is the same as when the hydraulic cylinder 10 is extended in the fluid pressure drive unit 100. Therefore, the hydraulic cylinder 10 is extended in the same way as in the fluid pressure drive unit 100, so a detailed explanation will be omitted.

[0064] To retract the hydraulic cylinder 10, the solenoid valve 131 is set to the first position D, and the solenoid valve 133 is set to the first position F, and the electric motor M is driven in reverse. The connection state of the hydraulic circuit at this time is the same as when the hydraulic cylinder 10 is retracted in the fluid pressure drive unit 100. Therefore, the hydraulic cylinder 10 retracts in the same manner as in the fluid pressure drive unit 100, so a detailed explanation is omitted.

[0065] Next, we will explain the case in which the hydraulic cylinder 50 is extended. When extending the hydraulic cylinder 50, the solenoid valve 131 is set to the second position E and the solenoid valve 133 is set to the second position G, and the electric motor M is driven in the forward direction. The connection state of the hydraulic circuit at this time is the same as when the hydraulic cylinder 50 is extended in the fluid pressure drive unit 100. Therefore, the hydraulic cylinder 50 is extended in the same way as in the fluid pressure drive unit 100, so a detailed explanation will be omitted.

[0066] To retract the hydraulic cylinder 50, the solenoid valve 131 is set to the second position E and the solenoid valve 133 is set to the second position G, and the electric motor M is driven in reverse. The connection state of the hydraulic circuit at this time is the same as when retracting the hydraulic cylinder 50 in the fluid pressure drive unit 100. Therefore, the hydraulic cylinder 50 retracts in the same manner as in the fluid pressure drive unit 100, so a detailed explanation is omitted.

[0067] Thus, in the fluid pressure drive unit 200, multiple hydraulic actuators (hydraulic cylinders 10, 50) can be driven by a single bidirectional pump (pump 20).

[0068] Next, with reference to Figure 6, a further modified example, a fluid pressure drive unit 300, will be described.

[0069] The fluid pressure drive unit 300 in this modified example differs from the fluid pressure drive unit 100 in that it does not include the third solenoid valve 33 and the fourth solenoid valve 34 found in the fluid pressure drive unit 100 of the above embodiment. In the following, only this difference will be explained, and identical components will be given the same numbering and their explanations will be omitted.

[0070] In this modified example, the fluid pressure drive unit 300 is used when the load is applied only when the hydraulic cylinders 10 and 50 are extended or retracted. In the example shown in Figure 6, the bottom chambers 14 and 51 of the hydraulic cylinders 10 and 50 are designated as the load side.

[0071] The operation of the fluid pressure drive unit 300 will be explained in detail.

[0072] When the electric motor M does not rotate and the pump 20 stops operating, the first solenoid valve 31 and the second solenoid valve 32 are closed. As a result, the hydraulic cylinders 10 and 50 remain in a load-holding state, holding the load without operating.

[0073] Next, the case in which the hydraulic cylinder 10 is extended will be described. When the hydraulic cylinder 10 is extended, the second solenoid valve 32 is opened and the first solenoid valve 31 is closed, and the electric motor M is driven in the forward direction. The connection state of the hydraulic circuit at this time is almost the same as when the hydraulic cylinder 10 is extended in the fluid pressure drive unit 100. Therefore, the hydraulic cylinder 10 is extended in the same manner as in the fluid pressure drive unit 100, so a detailed explanation of the extension operation will be omitted here. In this modified example, since the third solenoid valve 33 is not provided in the second communication passage 2C, the pressure of the hydraulic fluid discharged from the rod side chamber 15 of the hydraulic cylinder 10 acts on the rod side chamber 52 of the hydraulic cylinder 50. However, since the first solenoid valve 31 is closed, the hydraulic cylinder 50 does not operate.

[0074] Next, the case of retracting the hydraulic cylinder 10 will be described. When retracting the hydraulic cylinder 10, the second solenoid valve 32 is opened and the first solenoid valve 31 is closed, and the electric motor M is driven in reverse. The connection state of the hydraulic circuit at this time is the same as when retracting the hydraulic cylinder 10 in the fluid pressure drive unit 100. Therefore, the hydraulic cylinder 10 retracts in the same way as in the fluid pressure drive unit 100, so a detailed explanation will be omitted. In this modified example, since the third solenoid valve 33 is not provided in the second communication passage 2C, the pressure of the hydraulic fluid supplied to the rod side chamber 15 of the hydraulic cylinder 10 acts on the rod side chamber 52 of the hydraulic cylinder 50. However, since the first solenoid valve 31 is closed, the hydraulic cylinder 50 does not operate.

[0075] Next, we will describe the case in which the hydraulic cylinder 50 connected to the first port 36 and the second port 37 is operated.

[0076] When extending the hydraulic cylinder 50, the first solenoid valve 31 is opened and the second solenoid valve 32 is closed, and the electric motor M is driven in the forward direction. At this time, the connection state of the hydraulic circuit is the same as when extending the hydraulic cylinder 10. Therefore, the hydraulic cylinder 50 extends in the same manner as the fluid pressure drive unit 100, so a detailed explanation is omitted. In this modified example, since the fourth solenoid valve 34 is not provided in the rod-side passage 2, the pressure of the hydraulic fluid discharged from the rod-side chamber 52 of the hydraulic cylinder 50 acts on the rod-side chamber 15 of the hydraulic cylinder 10. However, since the second solenoid valve 32 is closed, the hydraulic cylinder 10 does not operate.

[0077] Next, the case of retracting the hydraulic cylinder 50 will be described. When retracting the hydraulic cylinder 50, the first solenoid valve 31 is opened and the second solenoid valve 32 is closed, and the electric motor M is driven in reverse. The connection state of the hydraulic circuit at this time is the same as when retracting the hydraulic cylinder 10 in the fluid pressure drive unit 100. Therefore, the hydraulic cylinder 50 retracts in the same way as the fluid pressure drive unit 100, so a detailed explanation will be omitted. In this modified example, since the fourth solenoid valve 34 is not provided in the rod-side passage 2, the pressure of the hydraulic fluid supplied to the rod-side chamber 52 of the hydraulic cylinder 50 acts on the rod-side chamber 15 of the hydraulic cylinder 10. However, since the second solenoid valve 32 is closed, the hydraulic cylinder 10 does not operate.

[0078] Thus, even with a fluid pressure drive unit 300 equipped only with a first solenoid valve 31 and a second solenoid valve 32, multiple hydraulic actuators (hydraulic cylinders 10, 50) can be driven by a single bidirectional pump (pump 20).

[0079] In this modified example, the bottom chambers 14 and 51 of the hydraulic cylinders 10 and 50 are designated as the load side, but the rod chambers 15 and 52 may also be designated as the load side. Even in this case, solenoid valves only need to be provided in the rod-side passage 2 and the second connecting passage 2C, which are the load side. Furthermore, in this modified example, the bottom chamber 14 of the hydraulic cylinder 10 may be designated as the load side, and the rod-side chamber 52 of the hydraulic cylinder 10 may also be designated as the load side. Alternatively, the rod-side chamber 15 of the hydraulic cylinder 10 may be designated as the load side, and the bottom chamber 51 of the hydraulic cylinder 10 may also be designated as the load side.

[0080] In the above embodiments and modifications, a switching valve was used as an example of a solenoid valve, but the invention is not limited to this, and a solenoid proportional control valve may also be used as the solenoid valve. In this case, the speed control of the hydraulic cylinders 10 and 50 can be easily performed. In addition, to control the speed of the hydraulic cylinders 10 and 50, for example, a meter-out control type flow control valve may be provided.

[0081] Furthermore, in the above embodiments and modifications, not all valves in the second valve unit 40 are essential. For example, relief valves 46, 47, etc., do not need to be provided.

[0082] The configuration, operation, and effects of the embodiments of the present invention will be described below.

[0083] The fluid pressure drive units 100, 200, and 300 include a hydraulic cylinder 10 (fluid pressure cylinder), a pump 20 (bidirectional pump) that discharges hydraulic fluid from one of the first pump port 20A and the second pump port 20B according to the rotation direction of the drive shaft and supplies hydraulic fluid to the hydraulic cylinder 10 (fluid pressure cylinder), a bottom side passage 1 (first passage) that connects the bottom side chamber 14 (first pressure chamber) of the hydraulic cylinder 10 (fluid pressure cylinder) and the first pump port 20A of the pump 20 (bidirectional pump), and the rod side chamber 15 (second pressure chamber) of the hydraulic cylinder 10 (fluid pressure cylinder) and the pump 20 (bidirectional pump). The system includes a rod-side passage 2 (second passage) connecting to the second pump port 20B, a first communication passage 1C branching off from the bottom-side passage 1 (first passage) and capable of communicating with external hydraulic cylinders 50, 60 (fluid pressure actuators), a first solenoid valve 31 and solenoid valve 131 (first switching unit) provided in the first communication passage 1C to control the flow of hydraulic oil (working fluid) in the first communication passage 1C, and a second solenoid valve 32 and solenoid valve 131 (second switching unit) provided on the hydraulic cylinder 10 (fluid pressure cylinder) side of the branching point between the bottom-side passage 1 (first passage) and the first communication passage 1C, to control the flow of hydraulic oil (working fluid) in the bottom-side passage 1 (first passage).

[0084] In this configuration, the hydraulic fluid discharged from the pump 20 (bidirectional pump) can be supplied to the external hydraulic cylinders 50 and 60 (fluid pressure actuators) through the first communication passage 1C. This allows a single pump 20 (bidirectional pump) to drive multiple fluid pressure actuators. Therefore, a fluid pressure drive unit capable of driving multiple fluid pressure actuators can be realized at low cost.

[0085] Furthermore, the fluid pressure drive units 100, 200 are characterized by further comprising: a second communication passage 2C that branches off from the rod-side passage 2 (second passage) and can communicate with external hydraulic cylinders 50, 60 (fluid pressure actuators); a third solenoid valve 33 and solenoid valve 133 (third switching unit) provided in the second communication passage 2C to control the flow of hydraulic oil (working fluid) in the second communication passage 2C; and a fourth solenoid valve 34 and solenoid valve 133 (fourth switching unit) provided on the hydraulic cylinder 10 (fluid pressure cylinder) side of the branching point between the rod-side passage 2 (second passage) and the second communication passage 2C, to control the flow of hydraulic oil (working fluid) flowing through the rod-side passage 2 (second passage).

[0086] In this configuration, two pressures can be supplied to the outside from the fluid pressure drive units 100 and 200 and controlled externally, thereby enabling the driving of a double-acting cylinder.

[0087] Furthermore, the fluid pressure drive unit 200 is configured such that the first and second switching sections are each made up of a single solenoid valve 131, and the third and fourth switching sections are each made up of a single solenoid valve 133.

[0088] This configuration allows for a reduction in the number of valves, thus suppressing cost increases.

[0089] Furthermore, the fluid pressure drive units 100, 200, and 300 further include a second valve block 35 (valve block) on which a first solenoid valve 31, a solenoid valve 131 (first switching section), and a second solenoid valve 32 and a solenoid valve 131 (second switching section) are provided. The second valve block 35 (valve block), hydraulic cylinder 10 (fluid pressure cylinder), and pump 20 (bidirectional pump) are configured as a single unit.

[0090] This configuration eliminates the need for piping and other components, allowing for a more compact unit.

[0091] Furthermore, the fluid pressure drive units 100, 200, and 300 are configured such that the second valve block 35 (valve block) is detachably installed between the hydraulic cylinder 10 (fluid pressure cylinder) and the pump 20 (bidirectional pump).

[0092] In this configuration, if the first solenoid valve 31, solenoid valve 131 (first switching section), and second solenoid valve 32 and solenoid valve 131 (second switching section) are not needed, the second valve block 35 (valve block) can be removed from the fluid pressure drive units 100, 200, and 300 and used separately. Furthermore, if the first solenoid valve 31, solenoid valve 131 (first switching section), and second solenoid valve 32 and solenoid valve 131 (second switching section) become necessary, the second valve block 35 (valve block) can be added to drive multiple fluid pressure actuators. Moreover, even if the type or method of use of the external fluid pressure actuator changes, the fluid pressure drive units 100, 200, and 300 can be used as is by replacing the second valve block 35 (valve block) with the corresponding one.

[0093] Furthermore, the fluid pressure drive unit includes a pump 20 (bidirectional pump) that discharges hydraulic oil (working fluid) from either the first pump port 20A or the second pump port 20B depending on the rotation direction of the drive shaft, a bottom-side passage 1 (first passage) connected to the first pump port 20A of the pump 20 (bidirectional pump) and connectable to the hydraulic cylinder 10 (first fluid pressure cylinder), and a rod-side passage 2 connected to the second pump port 20B of the pump 20 (bidirectional pump) and connectable to the hydraulic cylinder 10 (first fluid pressure cylinder). The system includes a second passage, a first connecting passage 1C that branches off from the bottom passage 1 (first passage) and is connectable to the hydraulic cylinder 50 (second fluid pressure cylinder), a first solenoid valve 31 (first switching unit) provided in the first connecting passage 1C for controlling the flow of hydraulic oil (working fluid) in the first connecting passage 1C, and a second solenoid valve 32 (second switching unit) provided on the side of the bottom passage 1 (first passage) away from the pump 20 (bidirectional pump) from the branching point with the first connecting passage 1C for controlling the flow of hydraulic oil (working fluid) in the bottom passage 1 (first passage).

[0094] In this configuration, hydraulic cylinders 10 can be connected to the bottom-side passage 1 and the rod-side passage 2, and hydraulic cylinder 50 can be connected to the first connecting passage 1C. This allows a single pump 20 (bidirectional pump) to drive multiple fluid pressure actuators. Therefore, a fluid pressure drive unit capable of driving multiple fluid pressure actuators can be realized at low cost.

[0095] Although embodiments of the present invention have been described above, these embodiments only represent a part of the application examples of the present invention, and are not intended to limit the technical scope of the present invention to the specific configurations of the above embodiments.

[0096] In the above embodiment, the case in which the hydraulic cylinders 10 and 50 are driven individually in the fluid pressure drive unit 100 was described as an example, but it is also possible to operate the hydraulic cylinders 10 and 50 simultaneously.

[0097] In the above embodiments and modifications, the case in which the hydraulic cylinder 10 and the first valve unit 30, and the first valve unit 30 and the second valve unit 40 are directly connected without using piping has been described, but they may also be connected using piping.

[0098] This application claims priority under Japanese Patent Application No. 2025-47980, filed with the Japan Patent Office on 24 March 2025, and all contents of that application are incorporated herein by reference.

Claims

1. A fluid pressure drive unit comprising: a fluid pressure cylinder; a bidirectional pump that discharges working fluid from one of a first pump port and a second pump port according to the rotation direction of the drive shaft and supplies working fluid to the fluid pressure cylinder; a first passage connecting the first pressure chamber of the fluid pressure cylinder and the first pump port of the bidirectional pump; a second passage connecting the second pressure chamber of the fluid pressure cylinder and the second pump port of the bidirectional pump; a first connecting passage branching off from the first passage and capable of communicating with an external fluid pressure actuator; a first switching unit provided in the first connecting passage for controlling the flow of working fluid in the first connecting passage; and a second switching unit provided on the fluid pressure cylinder side of the branching point between the first connecting passage and the first connecting passage for controlling the flow of working fluid in the first passage.

2. A fluid pressure drive unit according to claim 1, further comprising: a second communication passage branching from the second passage and communicating with an external fluid pressure actuator; a third switching unit provided in the second communication passage for controlling the flow of working fluid in the second communication passage; and a fourth switching unit provided on the fluid pressure cylinder side of the branching point between the second communication passage and the second communication passage for controlling the flow of working fluid flowing through the second passage.

3. A fluid pressure drive unit according to claim 2, wherein the first switching section and the second switching section are composed of one solenoid valve, and the third switching section and the fourth switching section are composed of one solenoid valve.

4. A fluid pressure drive unit according to claim 1, further comprising a valve block on which the first switching unit and the second switching unit are provided, wherein the valve block, the fluid pressure cylinder and the bidirectional pump are configured as a single unit.

5. A fluid pressure drive unit according to claim 4, wherein the valve block is detachably provided between the fluid pressure cylinder and the bidirectional pump.

6. A fluid pressure drive unit comprising: a bidirectional pump that discharges working fluid from one of a first pump port and a second pump port according to the rotation direction of the drive shaft; a first passage connected to the first pump port of the bidirectional pump and connectable to a first fluid pressure cylinder; a second passage connected to the second pump port of the bidirectional pump and connectable to the first fluid pressure cylinder; a first connecting passage branching off from the first passage and connectable to a second fluid pressure cylinder; a first switching unit provided in the first connecting passage for controlling the flow of working fluid in the first connecting passage; and a second switching unit provided on the side of the first passage away from the bidirectional pump at the branching point with the first connecting passage for controlling the flow of working fluid in the first passage.

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