Hydraulic actuator driving device

Abstract

To provide a hydraulic actuator driving device that can be easily miniaturized.SOLUTION: A directional control valve 21 can selectively switch between a first position where a hydraulic pump 19 can supply and discharge hydraulic fluid only to and from a first actuator 16, a second position where the hydraulic pump 19 can supply and discharge hydraulic fluid only to and from a second actuator 17, and a neutral position where the hydraulic pump 19 cannot supply and discharge hydraulic fluid to and from both of the first actuator 16 and the second actuator 17. The hydraulic pump 19 can switch between a state in which the hydraulic pump supplies and discharges hydraulic fluid to and from the target actuator (the first actuator 16, the second actuator 17) so that the target actuator extends and a state in which the hydraulic pump supplies and discharges hydraulic fluid to and from the target actuator so that the target actuator contracts, depending on a rotation direction of the hydraulic pump itself.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a hydraulic actuator drive. [Background technology]

[0002] 2. Description of the Related Art Wing trucks, which are configured so that cargo can be loaded and unloaded from a rectangular box-shaped loading platform in the width direction of the vehicle, are becoming popular among logistics trucks.

[0003] The cargo bed of a wing truck has a pair of wings on both sides in the width direction of the vehicle. Each wing is an opening and closing door made up of a roof panel and a side panel. The end of the roof panel that makes up each wing, located on the center side in the width direction of the vehicle, is connected to a fixed frame of the cargo bed that does not rotate or move relative to the chassis when the wings are opened or closed, allowing it to swing around a swing axis facing the fore-and-aft direction.

[0004] An actuator that can extend and retract its entire length is installed between the front and / or rear end of the roof panel that constitutes each wing and the fixed frame of the cargo bed, and the extension and contraction of the actuator causes each wing to swing relative to the fixed frame of the cargo bed, thereby opening and closing the wing. Specifically, when the actuator extends, each wing swings in the opening direction, and when the actuator contracts, each wing swings in the closing direction.

[0005] As the actuator capable of extending and contracting the entire length, a hydraulic actuator or an electric actuator can be used, but conventionally, a hydraulic actuator has been generally used.

[0006] For example, Japanese Patent Application Laid-Open No. 2003-120613 describes a hydraulic actuator drive device that includes a hydraulic actuator and is used in a wing opening / closing device. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-120613 Summary of the Invention [Problem to be solved by the invention]

[0008] FIG. 9 shows a hydraulic actuator driving device 100 of a prior invention having the same basic configuration as the hydraulic actuator driving device described in Japanese Patent Application Laid-Open No. 2003-120613.

[0009] The hydraulic actuator driving device 100 of the previous invention includes two first actuators 101, two second actuators 102, a hydraulic pump 103, a motor 104, a first directional control valve 106, and a second directional control valve 107.

[0010] The two first actuators 101 are used to open and close one of a pair of left and right wings, and extend and contract based on the supply and discharge of hydraulic oil.

[0011] The two second actuators 102 are used to open and close the other of the pair of left and right wings, and expand and contract based on the supply and discharge of hydraulic oil.

[0012] The hydraulic pump 103 is configured as a rotary pump, and is driven to rotate in only one direction by a motor 104 .

[0013] The two first actuators 101 and the two second actuators 102 are connected to the hydraulic pump 103 by a supply / discharge oil passage 105, which is a flow passage for hydraulic oil.

[0014] The first directional control valve 106 is disposed in a portion of the supply / discharge oil passage 105 that is located between the first actuator 101 and the hydraulic pump 103 .

[0015] The first directional control valve 106 is configured by an electromagnetic valve, and has a first extension solenoid 106a and a first contraction solenoid 106b. The first directional control valve 106 is switched to a position where hydraulic oil can be supplied or discharged to the first actuator 101 by the hydraulic pump 103 when current is applied only to the first extension solenoid 106a out of the first extension solenoid 106a and the first retraction solenoid 106b, and is switched to a position where hydraulic oil can be supplied or discharged to the first actuator 101 by the hydraulic pump 103 when current is applied only to the first retraction solenoid 106b out of the first extension solenoid 106a and the first retraction solenoid 106b, and is switched to a position where hydraulic oil cannot be supplied or discharged to the first actuator 101 by the hydraulic pump 103 when current is not applied to either the first extension solenoid 106a or the first retraction solenoid 106b.

[0016] The second directional control valve 107 is disposed in a portion of the supply / discharge oil passage 105 that is located between the second actuator 102 and the hydraulic pump 103 .

[0017] The second directional control valve 107 is configured by an electromagnetic valve, and has a second extension solenoid 107a and a second contraction solenoid 107b. The second directional control valve 107 is switched to a position where hydraulic oil can be supplied or discharged to the second actuator 102 by the hydraulic pump 103 to extend the second actuator 102 when current is applied only to the second extension solenoid 107a out of the second extension solenoid 107a and the second retraction solenoid 107b, and is switched to a position where hydraulic oil can be supplied or discharged to the second actuator 102 by the hydraulic pump 103 when current is applied only to the second retraction solenoid 107b out of the second extension solenoid 107a and the second retraction solenoid 107b, and is switched to a position where hydraulic oil cannot be supplied or discharged to the second actuator 102 by the hydraulic pump 103 when current is not applied to either the second extension solenoid 107a or the second retraction solenoid 107b.

[0018] When opening or closing one wing, current is applied to the first extension solenoid 106a or the first retraction solenoid 106b of the first direction control valve 106 while current is not applied to either the second extension solenoid 107a or the second retraction solenoid 107b of the second direction control valve 107. This causes the hydraulic pump 103 to supply or discharge hydraulic oil to the two first actuators 101 so that the two first actuators 101 extend or retract.

[0019] When opening or closing the other wing, the second extension solenoid 107a or the second retraction solenoid 107b of the second direction control valve 107 is energized while neither the first extension solenoid 106a nor the first retraction solenoid 106b of the first direction control valve 106 is energized. This causes the hydraulic pump 103 to supply or discharge hydraulic oil to the two second actuators 102 so that the two second actuators 102 extend or retract.

[0020] Such a hydraulic actuator drive device 100 of the prior invention is easily made larger because it is equipped with two directional control valves in total (first directional control valve 106 and second directional control valve 107), one for each of the pair of left and right wings.

[0021] An object of the present disclosure is to provide a hydraulic actuator drive device that can be easily downsized. [Means for solving the problem]

[0022] The hydraulic actuator drive device according to the first aspect of the present disclosure includes: a first actuator and a second actuator that expand and contract based on the supply and discharge of hydraulic oil; a reversible hydraulic pump for supplying and discharging hydraulic oil to and from the first actuator and the second actuator; a motor for rotating the hydraulic pump; and a directional control valve that is disposed between the hydraulic pump and the first and second actuators and is capable of selectively switching between a first position in which the hydraulic pump can supply or discharge hydraulic oil only to the first of the first and second actuators, a second position in which the hydraulic pump can supply or discharge hydraulic oil only to the second of the first and second actuators, and a neutral position in which the hydraulic pump cannot supply or discharge hydraulic oil to either the first or second actuator.

[0023] The hydraulic pump can switch between a state in which hydraulic oil is supplied or discharged to a target actuator, one of the first actuator and the second actuator, so that the target actuator expands, and a state in which hydraulic oil is supplied or discharged to the target actuator contracts, depending on the direction of rotation of the hydraulic pump itself.

[0024] A hydraulic actuator drive device of a second aspect of the present disclosure is the hydraulic actuator drive device of the first aspect of the present disclosure, The hydraulic oil pump further includes an oil tank for storing hydraulic oil and a flow control valve. each of the first actuator and the second actuator includes a cylinder, a piston fitted in the cylinder to divide the interior of the cylinder into an extension-side cylinder chamber and a contraction-side cylinder chamber, and a piston rod having one end coupled to the piston and inserted into the contraction-side cylinder chamber; The flow control valve opens based on the pressure of hydraulic oil flowing between the direction control valve and a port of the hydraulic pump from which hydraulic oil is discharged when the first actuator or the second actuator contracts, and releases a portion of the hydraulic oil flowing between the direction control valve and a port of the hydraulic pump from which hydraulic oil is sucked when the first actuator or the second actuator contracts, to the oil tank.

[0025] A hydraulic actuator drive device of a third aspect of the present disclosure is the hydraulic actuator drive device of the first or second aspect of the present disclosure, wherein the first actuator is composed of a plurality of first actuators and / or the second actuator is composed of a plurality of second actuators.

[0026] A hydraulic actuator drive device according to a fourth aspect of the present disclosure is the hydraulic actuator drive device according to any one of the first to third aspects of the present disclosure, the first actuator is used to open and close one of a pair of left and right wings swingably supported on a fixed frame in a loading platform of a winged vehicle; The second actuator is used to open and close the other of the pair of left and right wings. That is, the hydraulic actuator drive device according to the fourth aspect of the present disclosure is used in a wing opening and closing device. [Effects of the Invention]

[0027] According to the hydraulic actuator drive device of one aspect of the present disclosure, miniaturization can be easily achieved. [Brief explanation of the drawings]

[0028] [Figure 1] FIG. 1 is a perspective view, seen from the rear, of a wing vehicle incorporating a hydraulic actuator drive device according to an embodiment of the present disclosure. [Figure 2] FIG. 2 is a hydraulic circuit diagram of the hydraulic actuator drive device, showing a state in which the pair of left and right wings are closed. [Figure 3] FIG. 3 is a hydraulic circuit diagram of the hydraulic actuator drive unit, showing the process of opening the left wing while the right wing is closed. [Figure 4] FIG. 4 is a hydraulic circuit diagram of the hydraulic actuator drive device, showing a state in which the left wing is open and the right wing is maintained closed. [Figure 5]FIG. 5 is a hydraulic circuit diagram of the hydraulic actuator drive unit, showing the process of closing the left wing while the right wing is closed. [Figure 6] FIG. 6 is a hydraulic circuit diagram of the hydraulic actuator drive unit, showing the process of opening the right wing while the left wing is closed. [Figure 7] FIG. 7 is a hydraulic circuit diagram of the hydraulic actuator drive unit, showing a state in which the right wing is open and the left wing is maintained closed. [Figure 8] FIG. 8 is a hydraulic circuit diagram of the hydraulic actuator drive unit, showing the process of closing the right wing while the left wing is closed. [Figure 9] FIG. 9 is a hydraulic circuit diagram of a hydraulic actuator drive device according to the prior invention. DETAILED DESCRIPTION OF THE INVENTION

[0029] An example of an embodiment of the present disclosure will be described with reference to FIGS. 1 to 8. FIG.

[0030] A hydraulic actuator drive device according to one embodiment of the present disclosure can be widely used (applied) to devices that drive moving parts of various types of machinery, such as devices that drive moving parts of vehicles such as logistics trucks (for example, wing opening and closing devices for wing trucks, tailgate operating devices for tailgate trucks), and devices that drive moving parts of construction machinery and industrial machinery.

[0031] This example is an example in which a hydraulic actuator drive device according to one aspect of the present disclosure is used in a wing opening and closing device for a wing vehicle.

[0032] FIG. 1 shows a wing vehicle 2 incorporating a hydraulic actuator drive device 1 of this embodiment.

[0033] The wing truck 2 has a loading platform 3 that has a rectangular box shape when closed. The loading platform 3 has a bottom 4, a front panel 5, a rear frame 6, an upper central frame 7, a pair of left and right rear doors 8, a pair of left and right flap panels 9, a pair of left and right wings 10a, 10b, and a hydraulic actuator drive unit 1.

[0034] The bottom part 4 has a rectangular flat plate shape that extends in the front-to-rear direction when viewed from above, and forms the lower part of the loading platform 3. The bottom part 4 is supported and fixed to the upper part of the chassis 11 of the winged vehicle 2, at a part rearward of the cabin 12.

[0035] The front panel 5 has a rectangular flat plate shape when viewed from the front-rear direction, and constitutes the front portion of the loading platform 3. The lower end of the front panel 5 is joined and fixed to the front end of the bottom part 4.

[0036] The rear frame 6 has a rectangular frame shape when viewed from the front-rear direction, and forms the outer periphery of the rear portion of the loading platform 3. The lower end of the rear frame 6 is joined and fixed to the rear end of the bottom 4.

[0037] The upper central frame 7 has a beam shape that extends in the front-to-rear direction, and constitutes the center in the vehicle width direction of the upper part of the cargo bed 3. The upper central frame 7 spans between the center in the vehicle width direction of the upper end of the front panel 5 and the center in the vehicle width direction of the upper end of the rear frame 6. In other words, the front end of the upper central frame 7 is joined and fixed to the center in the vehicle width direction of the upper end of the front panel 5, and the rear end of the upper central frame 7 is joined and fixed to the center in the vehicle width direction of the upper end of the rear frame 6.

[0038] Of the cargo bed 3, the bottom 4, front panel 5, rear frame 6, and upper central frame 7 are fixed frames that do not rotate or displace relative to the chassis 11, even when the respective wings 10a, 10b are opened or closed to load or unload cargo.

[0039] The pair of left and right rear doors 8, together with the rear frame 6, constitute the rear portion of the cargo bed 3. The pair of left and right rear doors 8 are attached to the inside of the rear frame 6 so as to be able to be opened and closed in a double door style.

[0040] A pair of left and right flapboards 9 constitute the lower portions of both sides of the loading platform 3 in the vehicle width direction. The lower end of each flapboard 9 is connected to the end of the bottom 4 in the vehicle width direction so as to be able to swing about an axis facing in the front-to-rear direction. Each flapboard 9 can be opened and closed by swinging it outward in the vehicle width direction.

[0041] A pair of left and right wings 10a, 10b constitute the upper portions of both sides of the cargo bed 3 in the vehicle width direction. Each wing 10a, 10b is formed by combining a roof panel 13 and a side panel 14 to form an L-shape when viewed from the front to rear. That is, when closed, each wing 10a, 10b has a rectangular roof panel 13 arranged approximately parallel to the bottom 4 and a rectangular side panel 14 bent downward from the outer end of the roof panel 13 in the vehicle width direction. When each wing 10a, 10b is closed, the lower end of the side panel 14 abuts or closely faces the upper end of the gate 9, or is positioned outward and lower than the upper end of the gate 9 in the vehicle width direction. This closes off the interior space of the cargo bed 3. However, when each wing 10a, 10b is closed, the lower end of the side panel 14 can also be positioned higher than the upper end of the gate 9.

[0042] The end portion of the roof panel 13 constituting each of the wings 10a, 10b on the vehicle widthwise center side is connected to the end portion of the upper central frame 7 on the vehicle widthwise outer side so as to be able to swing about a swing axis facing in the front-to-rear direction. By swinging and displacing each of the wings 10a, 10b in the vertical direction about the swing axis, the wings 10a, 10b can be opened and closed.

[0043] The hydraulic actuator drive device 1 is used to open and close a pair of left and right wings 10a, 10b that are swingably supported on a fixed frame on the loading platform 3 of the wing vehicle 2.

[0044] As shown in FIG. 2, the hydraulic actuator driving device 1 includes a first actuator 16, a second actuator 17, a hydraulic pump 19, a motor 20, and a directional control valve 21.

[0045] The first actuator 16 is used to open and close one wing 10a of the pair of left and right wings 10a, 10b, and is configured as a hydraulic actuator that expands and contracts based on the supply and discharge of hydraulic oil. In this example, the one wing 10a is the left wing in the forward direction of the wing vehicle 2, and in the following explanation, it may be referred to as the left wing 10a as appropriate.

[0046] The first actuator 16 can be made up of one or more first actuators 16. In this example, the first actuator 16 is made up of two first actuators 16.

[0047] The two first actuators 16 are installed spaced apart in the front-to-rear direction, as shown in Fig. 1. Specifically, one end of the front first actuator 16 in the extension / contraction direction is connected to the upper end of the front panel 5, which is a fixed frame, so as to be able to swing about an axis facing the front-to-rear direction, and the other end of the front first actuator 16 in the extension / contraction direction is connected to the front end of the roof panel 13, which constitutes the left wing 10a, so as to be able to swing about an axis facing the front-to-rear direction. Furthermore, one end of the rear first actuator 16 in the extension / contraction direction is connected to the upper end of the rear frame 6, which is a fixed frame, so as to be able to swing about an axis facing the front-to-rear direction, and the other end of the rear first actuator 16 in the extension / contraction direction is connected to the rear end of the roof panel 13, which constitutes the left wing 10a, so as to be able to swing about an axis facing the front-to-rear direction.

[0048] The two first actuators 16 are configured to expand and contract in sync with each other based on the supply and discharge of hydraulic oil to each of them. When the two first actuators 16 expand, the left wing 10a swings in the opening direction, whereas when the two first actuators 16 contract, the left wing 10a swings in the closing direction.

[0049] More specifically, each first actuator 16 includes a cylinder 22, a piston 23, and a piston rod 24. The piston 23 is fitted into the cylinder 22. The interior of the cylinder 22 is divided by the piston 23 into an extension-side cylinder chamber 25 and a contraction-side cylinder chamber 26. The piston rod 24 has one end connected to the piston 23 and extends through the contraction-side cylinder chamber 26.

[0050] Each first actuator 16 extends when the pressure of hydraulic oil introduced into the extension-side cylinder chamber 25 becomes higher than the pressure of hydraulic oil introduced into the contraction-side cylinder chamber 26, and contracts when the pressure of hydraulic oil introduced into the contraction-side cylinder chamber 26 becomes higher than the pressure of hydraulic oil introduced into the extension-side cylinder chamber 25.

[0051] The second actuator 17 is used to open and close the other wing 10b of the pair of left and right wings 10a, 10b, and is configured as a hydraulic actuator that expands and contracts based on the supply and discharge of hydraulic oil. In this example, the other wing 10b is the right wing in the forward direction of the wing vehicle 2, and in the following explanation, it may be referred to as the right wing 10b as appropriate.

[0052] The second actuator 17 can be made up of one or more second actuators 17. In this example, the second actuator 17 is made up of two second actuators 17.

[0053] The two second actuators 17 are installed spaced apart in the front-to-rear direction, as shown in Fig. 1. Specifically, one end of the front second actuator 17 in the extension / contraction direction is connected to the upper end of the front panel 5, which is a fixed frame, so as to be able to swing about an axis facing the front-to-rear direction, and the other end of the front second actuator 17 in the extension / contraction direction is connected to the front end of the roof panel 13, which constitutes the right wing 10b, so as to be able to swing about an axis facing the front-to-rear direction. Furthermore, one end of the rear second actuator 17 in the extension / contraction direction is connected to the upper end of the rear frame 6, which is a fixed frame, so as to be able to swing about an axis facing the front-to-rear direction, and the other end of the rear second actuator 17 in the extension / contraction direction is connected to the rear end of the roof panel 13, which constitutes the right wing 10b, so as to be able to swing about an axis facing the front-to-rear direction.

[0054] The two second actuators 17 are configured to expand and contract in sync with each other based on the supply and discharge of hydraulic oil to and from them. When the two second actuators 17 expand, the right wing 10b swings in the opening direction, whereas when the two second actuators 17 contract, the right wing 10b swings in the closing direction.

[0055] More specifically, each second actuator 17 includes a cylinder 27, a piston 28, and a piston rod 29. The piston 28 is fitted into the cylinder 27. The interior of the cylinder 27 is divided by the piston 28 into an extension-side cylinder chamber 30 and a contraction-side cylinder chamber 31. The piston rod 29 has one end connected to the piston 28 and extends through the contraction-side cylinder chamber 31.

[0056] Each second actuator 17 extends when the pressure of hydraulic oil introduced into the extension-side cylinder chamber 30 becomes higher than the pressure of hydraulic oil introduced into the contraction-side cylinder chamber 31, and contracts when the pressure of hydraulic oil introduced into the contraction-side cylinder chamber 31 becomes higher than the pressure of hydraulic oil introduced into the extension-side cylinder chamber 30.

[0057] Hydraulic pump 19 is used to supply and discharge hydraulic oil to first actuator 16 and second actuator 17. Hydraulic pump 19 is configured as a reversible rotation hydraulic pump that can change the direction of hydraulic oil flow by changing the direction of rotation, and is rotationally driven by motor 20.

[0058] The hydraulic pump 19 has a first port P1 and a second port P2. When the hydraulic pump 19 is driven to rotate in the forward direction by the motor 20, the first port P1 becomes the port from which hydraulic oil is drawn in, and the second port P2 becomes the port from which hydraulic oil is discharged. When the hydraulic pump 19 is driven to rotate in the reverse direction by the motor 20, the second port P2 becomes the port from which hydraulic oil is drawn in, and the first port P1 becomes the port from which hydraulic oil is discharged.

[0059] The hydraulic pump 19 can switch between a state in which hydraulic oil is supplied or discharged to the target actuator, either the first actuator 16 or the second actuator 17, to which hydraulic oil is supplied or discharged so that the target actuator extends, and a state in which hydraulic oil is supplied or discharged so that the target actuator contracts, depending on the direction of its own rotation.

[0060] The directional control valve 21 is disposed between the hydraulic pump 19 and the first actuator 16 and the second actuator 17 .

[0061] That is, the first actuator 16, the second actuator 17 and the hydraulic pump 19 are connected by a supply / discharge oil passage 18, which is a flow passage for hydraulic oil. The directional control valve 21 is arranged in the supply / discharge oil passage 18, between the hydraulic pump 19 and the first actuator 16 and the second actuator 17.

[0062] The directional control valve 21 is configured as a three-position solenoid valve, and can be selectively switched between a first position in which the hydraulic pump 19 can supply or discharge hydraulic oil only to the first actuator 16 of the first actuator 16 and the second actuator 17; a second position in which the hydraulic pump 19 can supply or discharge hydraulic oil only to the second actuator 17 of the first actuator 16 and the second actuator 17; and a neutral position in which the hydraulic pump 19 cannot supply or discharge hydraulic oil to either the first actuator 6 or the second actuator 17.

[0063] Regarding the directional control valve 21, the configuration for selectively switching between the respective positions (first position, second position, neutral position) can be determined arbitrarily.

[0064] In this example, the directional control valve 21 has a first solenoid 32 and a second solenoid 33, and is switched to a first position by energizing only the first solenoid 32, is switched to a second position by energizing only the second solenoid 33, and is switched to a neutral position by not energizing either the first solenoid 32 or the second solenoid 33.

[0065] In this example, the directional control valve 21 has a first pump side port A1, a second pump side port A2, a tank side port T, a first load side port B1, a second load side port B2, a third load side port B3, and a fourth load side port B4.

[0066] When the directional control valve 21 is switched to the first position, as shown in Figures 3 and 5, the first pump side port A1 and the first load side port B1 are connected to each other, the second pump side port A2 and the second load side port B2 are connected to each other, and the tank side port T and the third load side port B3 and the fourth load side port B4 are connected to each other.

[0067] When the directional control valve 21 is switched to the second position, as shown in Figures 6 and 8, the first pump side port A1 and the third load side port B3 are connected to each other, the second pump side port A2 and the fourth load side port B4 are connected to each other, and the tank side port T and the first load side port B1 and the second load side port B2 are connected to each other.

[0068] When the directional control valve 21 is switched to the neutral position, as shown in Figures 2, 4, and 7, the first pump side port A1 and the second pump side port A2 are closed, and the tank side port T is connected to the first load side port B1 to the fourth load side port B4.

[0069] In this example, the supply / discharge oil passage 18 includes a first pump side oil passage 34, a second pump side oil passage 35, a tank side oil passage 44, a first load side oil passage 45, a second load side oil passage 47, a third load side oil passage 49, and a fourth load side oil passage 51.

[0070] The first pump-side oil passage 34 connects the first pump-side port A1 of the directional control valve 21 and the first port P1 of the hydraulic pump 19.

[0071] The second pump-side oil passage 35 connects the second pump-side port A2 of the directional control valve 21 and the second port P2 of the hydraulic pump 19.

[0072] The hydraulic actuator driving device 1 of this example further includes an oil tank 15 that stores hydraulic oil, and the tank-side oil passage 44 connects the tank-side port T of the directional control valve 21 and the oil tank 15.

[0073] The first load-side oil passage 45 connects the first load-side port B1 of the directional control valve 21 and the extension-side cylinder chambers 25 of the two first actuators 16. The end of the first load-side oil passage 45 on the side of the two first actuators 16 is configured as a pair of bifurcated first branch oil passages 46. The tip end of each of the first branch oil passages 46 is connected to the extension-side cylinder chambers 25 of the respective first actuators 16.

[0074] The second load-side oil passage 47 connects the second load-side port B2 of the directional control valve 21 and the contraction-side cylinder chambers 26 of the two first actuators 16. The end of the second load-side oil passage 47 on the side of the two first actuators 16 is configured as a pair of bifurcated second branch oil passages 48. The tip end of each second branch oil passage 48 is connected to the contraction-side cylinder chamber 26 of the corresponding first actuator 16.

[0075] The third load side oil passage 49 connects the third load side port B3 of the directional control valve 21 and the extension side cylinder chamber 30 of the second actuator 17. The two second actuator 17 side ends of the third load side oil passage 49 are configured as a pair of bifurcated third branch oil passages 50. The tip end of each third branch oil passage 50 is connected to the extension side cylinder chamber 30 of the corresponding second actuator 17.

[0076] The fourth load side oil passage 51 connects the fourth load side port B4 of the directional control valve 21 and the contraction side cylinder chamber 31 of the second actuator 17. The ends of the fourth load side oil passage 51 on the two second actuator 17 sides are configured as a pair of bifurcated fourth branch oil passages 52. The tip end of each of the fourth branch oil passages 52 is connected to the contraction side cylinder chamber 31 of the corresponding second actuator 17.

[0077] The hydraulic actuator driving device 1 of this example further includes a flow control valve 63 .

[0078] The flow control valve 63 opens based on the pressure of the hydraulic oil flowing between the port of the first port P1 or the second port P2 of the hydraulic pump 19 from which hydraulic oil is discharged when the first actuator 16 or the second actuator 17 contracts and the directional control valve 21 (in this example, the second pump side oil passage 35), and releases a portion of the hydraulic oil flowing between the port of the first port P1 or the second port P2 of the hydraulic pump 19 from which hydraulic oil is sucked when the first actuator 16 or the second actuator 17 contracts and the directional control valve 21 (in this example, the first pump side oil passage 34) to the oil tank 15.

[0079] For this reason, in this example, the supply / discharge oil passage 18 further includes a flow rate control oil passage 64 that connects a part of the first pump side oil passage 34 to the oil tank 15. The flow rate control valve 63 is arranged in the flow rate control oil passage 64.

[0080] In this example, the supply and discharge oil passage 18 further includes a first supply oil passage 66 connecting a portion of the first pump side oil passage 34 to the oil tank 15, and a second supply oil passage 67 connecting a portion of the second pump side oil passage 35 to the oil tank 15.

[0081] In the first oil supply passage 66, a first filter 36 and a first pump side check valve 37 are arranged in this order from the oil tank 15 side. The first pump side check valve 37 prevents backflow of hydraulic oil from the first pump side oil passage 34 side to the oil tank 15 side. The first filter 36 filters the hydraulic oil passing through it.

[0082] In the second supply oil passage 67, a second filter 38 and a second pump side check valve 39 are arranged in this order from the oil tank 15 side. The second pump side check valve 39 prevents backflow of hydraulic oil from the second pump side oil passage 35 side to the oil tank 15 side. The second filter 38 filters the hydraulic oil passing through it.

[0083] In this example, the supply / discharge oil passage 18 further includes a first relief oil passage 40 that connects a portion of the first pump-side oil passage 34 to the oil tank 15. A first relief valve 41, which is a safety valve, is arranged in the first relief oil passage 40.

[0084] In this example, the supply / discharge oil passage 18 further includes a second relief oil passage 42 that connects a part of the second pump-side oil passage 35 to the oil tank 15. A second relief valve 43, which is a safety valve, is arranged in the second relief oil passage 42.

[0085] In this example, a first pilot check valve 53 is arranged in the first load side oil passage 45, in a portion located closer to the directional control valve 21 than the pair of first branch oil passages 46, to prevent backflow of hydraulic oil toward the directional control valve 21.

[0086] In this example, a second pilot check valve 54 is arranged in the second load side oil passage 47 in a portion located closer to the directional control valve 21 than the pair of second branch oil passages 48 to prevent backflow of hydraulic oil toward the directional control valve 21.

[0087] A pilot circuit 53 a of the first pilot check valve 53 is connected to a portion of the second load-side oil passage 47 that is located closer to the directional control valve 21 than the second pilot check valve 54 .

[0088] A pilot circuit 54 a of the second pilot check valve 54 is connected to a portion of the first load-side oil passage 45 that is located closer to the directional control valve 21 than the first pilot check valve 53 .

[0089] In this example, a third pilot check valve 55 is arranged in the third load side oil passage 49, in a portion located closer to the directional control valve 21 than the pair of third branch oil passages 50, to prevent backflow of hydraulic oil toward the directional control valve 21.

[0090] In this example, a fourth pilot check valve 56 is arranged in the fourth load side oil passage 51 in a portion located closer to the directional control valve 21 than the pair of fourth branch oil passages 52 to prevent backflow of hydraulic oil toward the directional control valve 21.

[0091] A pilot circuit 55 a of the third pilot check valve 55 is connected to a portion of the fourth load-side oil passage 51 that is located closer to the directional control valve 21 than the fourth pilot check valve 56 .

[0092] A pilot circuit 56 a of the fourth pilot check valve 56 is connected to a portion of the third load-side oil passage 49 that is located closer to the directional control valve 21 than the third pilot check valve 55 .

[0093] In this example, a first slow return valve 57 is disposed in a portion of first load-side oil passage 45 that is located between first pilot check valve 53 and the pair of first branch oil passages 46. First slow return valve 57 is composed of a check valve 57a and a throttle valve 57b. When hydraulic oil is supplied to the extension-side cylinder chambers 25 of the two first actuators 16, check valve 57a is opened. When hydraulic oil is discharged from the extension-side cylinder chambers 25 of the two first actuators 16, check valve 57a is closed and the hydraulic oil is gradually returned to the oil tank 15 through throttle valve 57b, preventing the left wing 10a from being suddenly closed.

[0094] In this example, a second slow return valve 58 is disposed in a portion of the third load side oil passage 49 that is located between the third pilot check valve 55 and the pair of third branch oil passages 50. The second slow return valve 58 is composed of a check valve 58a and a throttle valve 58b. When hydraulic oil is supplied to the extension-side cylinder chambers 30 of the two second actuators 17, the check valve 58a of the second slow return valve 58 is opened. However, when hydraulic oil is discharged from the extension-side cylinder chambers 30 of the two second actuators 17, the check valve 58a is closed and the hydraulic oil is gradually returned to the oil tank 15 through the throttle valve 58b, thereby preventing the right wing 10b from closing suddenly.

[0095] In this example, the supply / discharge oil passage 18 further includes a first discharge passage 59 that connects a portion of the first load-side oil passage 45 that is located between the first pilot check valve 53 and the first slow return valve 57 to the oil tank 15. A first stop valve 60 that is opened only in the event of an emergency is disposed in the first discharge passage 59.

[0096] If an emergency occurs in which the hydraulic pump 19 is unable to supply or discharge hydraulic oil to the two first actuators 16 due to a malfunction or other reason when the first actuators 16 are extended, i.e., when the left wing 10a is open, an operator can manually open the first stop valve 60, which will return the hydraulic oil in the extension side cylinder chambers 25 of the two first actuators 16 to the oil tank 15 through the first load side oil passage 45 and the first discharge passage 59, thereby contracting the two first actuators 16 and closing the left wing 10a.

[0097] In this example, the supply / discharge oil passage 18 further includes a second discharge passage 61 that connects a portion of the third load-side oil passage 49 that is located between the third pilot check valve 55 and the second slow return valve 58 to the oil tank 15. A second stop valve 62 that is opened only in the event of an emergency is disposed in the second discharge passage 61.

[0098] If an emergency occurs in which the hydraulic pump 19 is unable to supply or discharge hydraulic oil to the two second actuators 17 due to a malfunction or other reason when the second actuators 17 are extended, i.e., when the right wing 10b is open, an operator can manually open the second stop valve 62, which will return the hydraulic oil in the extension side cylinder chambers 30 of the two second actuators 17 to the oil tank 15 via the third load side oil passage 49 and the second discharge passage 61, thereby contracting the two second actuators 17 and closing the right wing 10b.

[0099] The hydraulic actuator drive device 1 of this example includes a controller 65 for opening and closing the pair of left and right wings 10a, 10b. The controller 65 includes a left switch 65a that an operator uses to issue an opening / closing command for the left wing 10a, and a right switch 65b that an operator uses to issue an opening / closing command for the right wing 10b.

[0100] The operation of the hydraulic actuator driving device 1 of this embodiment will be described below.

[0101] While the wing vehicle 2 is traveling, the left wing 10a and the right wing 10b are each maintained in a closed state.

[0102] That is, at this time, the two first actuators 16 for opening and closing the left wing 10a and the two second actuators 17 for opening and closing the right wing 10b are each maintained in a contracted state.

[0103] 2, the directional control valve 21 is switched to a neutral position by stopping (turning OFF) the supply of current to the first solenoid 32 and the second solenoid 33, thereby closing the first pump-side port A1 and the second pump-side port A2 and connecting the tank-side port T with the first load-side port B1 to the fourth load-side port B4. In addition, the supply of current to the motor 20 for driving the hydraulic pump 19 is stopped, thereby stopping the rotation of the hydraulic pump 19.

[0104] When loading or unloading cargo onto or from the bed 3 of the wing vehicle 2, when opening the left wing 10a, the worker can issue an opening command from the left switch 65a (for example, by pressing the opening command button) to cause the left wing 10a to open.

[0105] That is, when an operator issues an open command from the left switch 65a, as shown in Fig. 3, the first solenoid 32 of the directional control valve 21 is energized (turned ON). As a result, the directional control valve 21 is switched to the first position, thereby connecting the first pump-side port A1 to the first load-side port B1, connecting the second pump-side port A2 to the second load-side port B2, and connecting the tank-side port T to the third load-side port B3 and the fourth load-side port B4. This allows hydraulic oil from the hydraulic pump 19 to be supplied to and discharged only from the extension-side cylinder chamber 25 and the contraction-side cylinder chamber 26 of the two first actuators 16. Furthermore, when the motor 20 is energized, the motor 20 drives the hydraulic pump 19 to rotate in the forward direction.

[0106] As a result, as shown by the thick solid arrows in FIG. 3 , the hydraulic oil discharged from the first port P1 of the hydraulic pump 19 is supplied to the extension-side cylinder chambers 25 of the two first actuators 16 via the first pump-side oil passage 34 → the directional control valve 21 → a portion of the first load-side oil passage 45 that is closer to the directional control valve 21 than the pair of first branch oil passages 46 → the first pilot check valve 53 → the check valve 57a of the first slow return valve 57 → the pair of first branch oil passages 46.

[0107] At the same time, hydraulic oil pressure is applied from the primary side (direction control valve 21 side) of the first pilot check valve 53 to the second pilot check valve 54 via the pilot circuit 54a, causing the second pilot check valve 54 to open, allowing the hydraulic oil to flow back toward the direction control valve 21 side in the second pilot check valve 54.

[0108] Then, as shown by the thick dashed arrows in FIG. 3 , the hydraulic oil in the contraction-side cylinder chambers 26 of the two first actuators 16 is sucked into the hydraulic pump 19 from the second port P2 of the hydraulic pump 19 via a portion of the pair of second branch oil passages 48 → the second pilot check valve 54 → the second load-side oil passage 47 that is closer to the direction control valve 21 than the pair of second branch oil passages 48 → the direction control valve 21 → the second pump-side oil passage 35.

[0109] As a result of the above-described supply and discharge of hydraulic oil to the extension side cylinder chamber 25 and the contraction side cylinder chamber 26 of the two first actuators 16, the two first actuators 16 perform extension operations in synchronization, and the left wing 10a gradually swings in the opening direction.

[0110] Thereafter, when the left wing 10a is opened to a predetermined opening degree, as shown in Figure 4, the first solenoid 32 of the directional control valve 21 is de-energized (turned OFF), and the directional control valve 21 returns to the neutral position. At the same time, the motor 20 is de-energized, and the rotation of the hydraulic pump 19 stops. In this state, the same holding state as the closed state shown in Figure 2 is created, so the left wing 10a can be maintained open at the predetermined opening degree.

[0111] In addition, before the left wing 10a is opened to the specified opening degree, the operator can cancel the opening command from the left switch 65a (for example, by pressing the command cancel button), thereby canceling the power supply to the first solenoid 32 and the power supply to the motor 20, thereby stopping the opening operation of the left wing 10a.

[0112] Next, when closing the opened left wing 10a, the worker can issue a closing command from the left switch 65a (for example, by pressing a closing command button) to perform the closing operation of the left wing 10a.

[0113] That is, when the operator issues a close command from the left switch 65a, the first solenoid 32 of the directional control valve 21 is energized (turned ON) as shown in Fig. 5. This switches the directional control valve 21 to the first position. In addition, the motor 20 is energized, and the motor 20 drives the hydraulic pump 19 in the reverse rotation direction.

[0114] As a result, the hydraulic oil discharged from the second port P2 of the hydraulic pump 19 is supplied to the contraction-side cylinder chambers 26 of the two first actuators 16 via the second pump-side oil passage 35 → the directional control valve 21 → a portion of the second load-side oil passage 47 that is closer to the directional control valve 21 than the pair of second branch oil passages 48 → the second pilot check valve 54 → the pair of second branch oil passages 48, as shown by the thick dashed arrow in FIG. 5.

[0115] At the same time, hydraulic oil pressure is applied from the primary side (direction control valve 21 side) of the second pilot check valve 54 to the first pilot check valve 53 via the pilot circuit 53a, opening the first pilot check valve 53 and allowing the hydraulic oil to flow back toward the direction control valve 21 side in the first pilot check valve 53.

[0116] Then, as shown by thick solid arrows in FIG. 5 , the hydraulic oil in the extension-side cylinder chambers 25 of the two first actuators 16 passes through the pair of first branch oil passages 46 → the throttle valve 57b of the first slow return valve 57 → the first pilot check valve 53 → a portion of the first load-side oil passage 45 that is closer to the directional control valve 21 than the pair of first branch oil passages 46 → the directional control valve 21 → the first pump-side oil passage 34, and is then sucked into the hydraulic pump 19 from the first port P1 of the hydraulic pump 19.

[0117] As a result of the above-described supply and discharge of hydraulic oil to the extension side cylinder chamber 25 and the contraction side cylinder chamber 26 of the two first actuators 16, the two first actuators 16 perform contraction operations in synchronization, and the left wing 10a gradually swings in the closing direction.

[0118] Thereafter, when the left wing 10a is completely closed, as shown in Figure 2, the first solenoid 32 of the directional control valve 21 is de-energized (turned OFF), and the directional control valve 21 returns to the neutral position. At the same time, the motor 20 is de-energized, and the rotation of the hydraulic pump 19 stops. In this state, the same holding state as that described above when the left wing 10a is closed is created, so the left wing 10a can remain closed.

[0119] In addition, before the left wing 10a is completely closed, the operator can cancel the closing command from the left switch 65a (for example, by pressing the command cancel button), thereby canceling the power supply to the first solenoid 32 and the motor 20, thereby stopping the closing operation of the left wing 10a.

[0120] When loading or unloading luggage onto or from the bed 3 of the wing vehicle 2, the worker can open the right wing 10b by issuing an opening command from the right switch 65b.

[0121] That is, when an operator issues an open command from the right switch 65b, as shown in Fig. 6, the second solenoid 33 of the directional control valve 21 is energized (turned ON). As a result, the directional control valve 21 is switched to the second position, thereby connecting the first pump-side port A1 to the third load-side port B3, connecting the second pump-side port A2 to the fourth load-side port B4, and connecting the tank-side port T to the first load-side port B1 and the second load-side port B2. This allows hydraulic oil from the hydraulic pump 19 to be supplied to and discharged only from the extension-side cylinder chamber 30 and the contraction-side cylinder chamber 31 of the two second actuators 17. In addition, when the motor 20 is energized, the motor 20 rotates the hydraulic pump 19 in the forward direction.

[0122] As a result, as shown by the thick solid arrows in FIG. 6 , the hydraulic oil discharged from the first port P1 of the hydraulic pump 19 is supplied to the extension-side cylinder chambers 30 of the two second actuators 17 via the first pump-side oil passage 34 → the directional control valve 21 → a portion of the third load-side oil passage 49 that is closer to the directional control valve 21 than the pair of third branch oil passages 50 → the third pilot check valve 55 → the check valve 58a of the second slow return valve 58 → the pair of third branch oil passages 50.

[0123] At the same time, hydraulic oil pressure is applied from the primary side (directional control valve 21 side) of the third pilot check valve 55 to the fourth pilot check valve 56 via the pilot circuit 56a, causing the fourth pilot check valve 56 to open, allowing hydraulic oil to flow back toward the directional control valve 21 side in the fourth pilot check valve 56.

[0124] Then, as shown by the thick dashed arrow in FIG. 6 , the hydraulic oil in the contraction-side cylinder chambers 31 of the two second actuators 17 is sucked into the hydraulic pump 19 from the second port P2 of the hydraulic pump 19 via a pair of fourth branch oil passages 52 → the fourth pilot check valve 56 → a portion of the fourth load-side oil passage 51 that is closer to the directional control valve 21 than the pair of fourth branch oil passages 52 → the directional control valve 21 → the second pump-side oil passage 35.

[0125] As a result of the above-described supply and discharge of hydraulic oil to the extension side cylinder chamber 30 and the contraction side cylinder chamber 31 of the two second actuators 17, the two second actuators 17 perform extension operations in synchronization, and the right wing 10b gradually swings in the opening direction.

[0126] Thereafter, when the right wing 10b is opened to a predetermined opening degree, the second solenoid 33 of the directional control valve 21 is de-energized (turned OFF), and the directional control valve 21 returns to the neutral position, as shown in Figure 7. At the same time, the motor 20 is de-energized, and the rotation of the hydraulic pump 19 stops. In this state, the same holding state as when the right wing 10b is closed as shown in Figure 2 is created, so the right wing 10b can be maintained open at the predetermined opening degree.

[0127] In addition, before the right wing 10b is opened to the specified opening degree, the operator can cancel the opening command from the right switch 65b, thereby de-energizing the second solenoid 33 and the motor 20, thereby stopping the opening operation of the right wing 10b.

[0128] Next, when closing the opened right wing 10b, the worker can issue a closing command from the right switch 65b to perform the closing operation of the right wing 10b.

[0129] That is, when the operator issues a close command from the right switch 65b, the second solenoid 33 of the directional control valve 21 is energized (turned ON) as shown in Fig. 8. This switches the directional control valve 21 to the second position. In addition, the motor 20 is energized, and the motor 20 drives the hydraulic pump 19 to rotate in the reverse direction.

[0130] As a result, the hydraulic oil discharged from the second port P2 of the hydraulic pump 19 is supplied to the contraction-side cylinder chambers 31 of the two second actuators 17 via the second pump-side oil passage 35 → the directional control valve 21 → a portion of the fourth load-side oil passage 51 that is closer to the directional control valve 21 than the pair of fourth branch oil passages 52 → the fourth pilot check valve 56 → the pair of fourth branch oil passages 52, as shown by the thick dashed arrow in FIG. 8.

[0131] At the same time, hydraulic oil pressure is applied from the primary side (directional control valve 21 side) of the fourth pilot check valve 56 to the third pilot check valve 55 via the pilot circuit 55a, causing the third pilot check valve 55 to open, allowing the hydraulic oil to flow back toward the directional control valve 21 side in the third pilot check valve 55.

[0132] Then, as shown by the thick solid arrows in FIG. 8 , the hydraulic oil in the extension-side cylinder chambers 30 of the two second actuators 17 passes through a pair of third branch oil passages 50 → the throttle valve 58b of the second slow return valve 58 → the third pilot check valve 55 → a portion of the third load-side oil passage 49 that is closer to the directional control valve 21 than the pair of third branch oil passages 50 → the directional control valve 21 → the first pump-side oil passage 34, and is then sucked into the hydraulic pump 19 from the first port P1 of the hydraulic pump 19.

[0133] As a result of the above-described supply and discharge of hydraulic oil to the extension side cylinder chamber 30 and the contraction side cylinder chamber 31 of the two second actuators 17, the two second actuators 17 perform contraction operations in synchronization, and the right wing 10b gradually swings in the closing direction.

[0134] Thereafter, when the right wing 10b is completely closed, as shown in Figure 2, the second solenoid 33 of the directional control valve 21 is de-energized (turned OFF), and the directional control valve 21 returns to the neutral position. At the same time, the motor 20 is de-energized, and the rotation of the hydraulic pump 19 stops. In this state, the same holding state as that described above when the right wing 10b is closed is created, so the right wing 10b can remain closed.

[0135] In addition, before the right wing 10b is completely closed, the operator can cancel the closing command from the right switch 65b, thereby de-energizing the second solenoid 33 and the motor 20, thereby stopping the closing operation of the right wing 10b.

[0136] The hydraulic actuator driving device 1 of this example can open and close the left wing 10a while the right wing 10b is open, and can also open and close the right wing 10b while the left wing 10a is open.

[0137] 2, 4, and 7, when the directional control valve 21 is switched to the neutral position, the tank-side port T communicates with the first load-side port B1 to the fourth load-side port B4. At this time, if hydraulic oil is present in the first load-side oil passage 45, the second load-side oil passage 47, the third load-side oil passage 49, and the fourth load-side oil passage 51 in a portion closer to the directional control valve 21 than the pilot check valves (first pilot check valve 53, second pilot check valve 54, third pilot check valve 55, fourth pilot check valve 56) arranged in each oil passage, the hydraulic oil is returned to the oil tank 15 via the directional control valve 21 → tank-side oil passage 44.

[0138] 3 and 5, when the directional control valve 21 is switched to the first position, the tank-side port T communicates with the third load-side port B3 and the fourth load-side port B4. At this time, if hydraulic oil is present in the third load-side oil passage 49 and the fourth load-side oil passage 51 in a portion closer to the directional control valve 21 than the pilot check valves (third pilot check valve 55, fourth pilot check valve 56) arranged in the respective oil passages, the hydraulic oil is returned to the oil tank 15 via the directional control valve 21 → tank-side oil passage 44.

[0139] 6 and 8, when the directional control valve 21 is switched to the second position, the tank-side port T communicates with the first load-side port B1 and the second load-side port B2. At this time, if hydraulic oil is present in the first load-side oil passage 45 and the second load-side oil passage 47 in a portion closer to the directional control valve 21 than the pilot check valves (first pilot check valve 53, second pilot check valve 54) arranged in the respective oil passages, the hydraulic oil is returned to the oil tank 15 via the directional control valve 21 → tank-side oil passage 44.

[0140] In this example, when the two first actuators 16 shown in FIG. 3 are extending and / or the two second actuators 17 shown in FIG. 6 are extending, if there is a shortage of hydraulic oil discharged from the first port P1 of the hydraulic pump 19, the shortage of hydraulic oil is sucked (replenished) into the hydraulic pump 19 from the second port P2 via the oil tank 15 → second supply oil passage 67 → second filter 38 → second pump side check valve 39 → second pump side oil passage 35, as shown by the thin solid arrow α1.

[0141] In this example, when the two first actuators 16 shown in FIG. 3 and / or the two second actuators 17 shown in FIG. 6 are extending, if an abnormality occurs, such as a load being applied to the wings (10a, 10b) that inhibits the extension of the actuators (first actuator 16, second actuator 17), and the pressure of the hydraulic oil in the first pump-side oil passage 34 reaches the set pressure of the first relief valve 41, the first relief valve 41 opens. Then, as indicated by thin solid arrow β1, the hydraulic oil in the first pump-side oil passage 34 is released to the oil tank 15 via the first relief oil passage 40 and the first relief valve 41. As a result, the pressure of the hydraulic oil in the first pump-side oil passage 34 is regulated to be equal to or lower than the set pressure of the first relief valve 41, and the safety of the hydraulic circuit is maintained.

[0142] In this example, if there is a shortage of hydraulic oil discharged from the second port P2 of the hydraulic pump 19 during the contraction operation of the two first actuators 16 shown in Figure 5 and / or during the contraction operation of the two second actuators 17 shown in Figure 8, the shortage of hydraulic oil is sucked (replenished) into the hydraulic pump 19 from the second port P2 via the oil tank 15 → first supply oil passage 66 → first filter 36 → first pump side check valve 37 → first pump side oil passage 34, as shown by the thin dashed arrow α2.

[0143] In this example, when the two first actuators 16 shown in FIG. 5 and / or the two second actuators 17 shown in FIG. 8 are contracting, if an abnormality occurs, such as a load being applied to the wings (10a, 10b) that inhibits the contraction of the actuators (first actuators 16, second actuators 17), and the pressure of the hydraulic oil in the second pump-side oil passage 35 reaches the set pressure of the second relief valve 43, the second relief valve 43 opens. Then, as indicated by a thin solid arrow β2, the hydraulic oil in the second pump-side oil passage 35 is released to the oil tank 15 via the second relief oil passage 42 and the second relief valve 43. As a result, the pressure of the hydraulic oil in the second pump-side oil passage 35 is regulated to be equal to or lower than the set pressure of the second relief valve 43, thereby maintaining the safety of the hydraulic circuit.

[0144] 5 and / or the two second actuators 17 shown in Fig. 8, in each actuator (first actuator 16, second actuator 17), the amount of hydraulic oil discharged from the extension-side cylinder chamber (25, 30) is greater than the amount of hydraulic oil supplied to the contraction-side cylinder chamber (26, 31) by the volume of the piston rod (24, 29) inserted through the contraction-side cylinder chamber (26, 31). As a result, the pressure of the hydraulic oil in the second pump-side oil passage 35 that delivers the hydraulic oil toward the contraction-side cylinder chamber (26, 31) tends to increase.

[0145] In this example, when the pressure of the hydraulic oil in the second pump-side oil passage 35 reaches the set pressure of the flow control valve 63, the flow control valve 63 opens and releases a portion of the hydraulic oil flowing in the first pump-side oil passage 34 to the oil tank 15 via the flow control oil passage 64 and the flow control valve 63. This suppresses unnecessary pressure increases in the hydraulic oil flowing in the second pump-side oil passage 35. In this example, the power consumption of the motor 20 for rotationally driving the hydraulic pump 19 can be reduced by the amount that such unnecessary pressure increases are suppressed.

[0146] The set pressure for opening the flow control valve 63 is sufficiently smaller than the set pressure for opening the second relief valve 43 when an abnormality occurs. Therefore, the second relief valve 43 does not open during normal operation when no abnormality occurs.

[0147] As described above, in the hydraulic actuator drive system 1 of this example, the directional control valves for opening and closing the pair of left and right wings 10a, 10b, i.e., for extending and retracting the first actuator 16 and the second actuator 17, can be configured with a single directional control valve 21. This makes it easy to reduce the size, cost, and number of parts of the hydraulic actuator drive system 1. [Explanation of symbols]

[0148] 1 Hydraulic actuator drive unit 2 Winged vehicles 3 Cargo bed 4 Bottom 5 Front Panel 6 Rear frame 7 Upper center frame 8 Rear door 9. Provocation Board 10a, 10b Wing 11 Chassis 12 Cabins 13 Roof Panels 14 Side Panel 15 Oil Tank 16 First Actuator 17 Second Actuator 18 Oil supply and drainage passage 19 Hydraulic pump 20 Motor 21 Directional control valve 22 cylinders 23 Piston 24 Piston rod 25 Extension side cylinder chamber 26 Contraction side cylinder chamber 27 cylinders 28 Piston 29 Piston rod 30 Extension side cylinder chamber 31 Contraction side cylinder chamber 32 First solenoid 33 Second solenoid 34 First pump side oil passage 35 Second pump side oil passage 36 First filter 37 First pump side check valve 38 Second Filter 39 Second pump side check valve 40 First relief oil passage 41 First relief valve 42 Second relief oil passage 43 Second relief valve 44 Tank side oil passage 45 1st load side oil path 46 First Branch Oil Channel 47 2nd load side oil path 48 Second Branch Oil Channel 49 3rd load side oil path 50 Third Branch Oil Channel 51 4th load side oil path 52 4th Branch Oil Channel 53 First pilot check valve 53a Pilot Circuit 54 Second pilot check valve 54a Pilot circuit 55 Third pilot check valve 55a Pilot Circuit 56 4th pilot check valve 56a Pilot Circuit 57 First slow return valve 57a Check valve 57b Throttle valve 58 Second slow return valve 58a Check valve 58b Throttle valve 59 1st discharge channel 60 First stop valve 61 2nd discharge channel 62 Second stop valve 63 Flow control valve 64 Oil passage for flow control 65 Controller 65a Left switch 65b Right switch 66 First oil supply line 67 Second oil supply line 100 Hydraulic actuator drive unit 101 First Actuator 102 Second Actuator 103 Hydraulic pump 104 Motor 105 Oil supply and drainage path 106 First directional control valve 106a First extension solenoid 106b First contraction solenoid 107 Second directional control valve 107a Second extension solenoid 107b Second contraction solenoid

Claims

1. a first actuator and a second actuator that expand and contract based on the supply and discharge of hydraulic oil; a reversible hydraulic pump for supplying and discharging hydraulic oil to and from the first actuator and the second actuator; a motor for rotating the hydraulic pump; a directional control valve that is disposed between the hydraulic pump and the first and second actuators and is selectively switchable between a first position where the hydraulic pump can supply or discharge hydraulic oil only to the first actuator of the first and second actuators, a second position where the hydraulic pump can supply or discharge hydraulic oil only to the second actuator of the first and second actuators, and a neutral position where the hydraulic pump cannot supply or discharge hydraulic oil to either the first or second actuator, The hydraulic pump is capable of switching, depending on its rotation direction, between a state in which hydraulic oil is supplied or discharged to a target actuator, one of the first actuator and the second actuator, so that the target actuator expands, and a state in which hydraulic oil is supplied or discharged to the target actuator so that the target actuator contracts. Hydraulic actuator drive unit.

2. The hydraulic oil pump further includes an oil tank for storing hydraulic oil and a flow control valve. each of the first actuator and the second actuator includes a cylinder, a piston fitted in the cylinder to divide the interior of the cylinder into an extension-side cylinder chamber and a contraction-side cylinder chamber, and a piston rod having one end coupled to the piston and inserted into the contraction-side cylinder chamber; the flow rate control valve opens based on the pressure of hydraulic oil flowing between the direction control valve and a port of the hydraulic pump from which hydraulic oil is discharged when the first actuator or the second actuator contracts, and releases a portion of the hydraulic oil flowing between the direction control valve and a port of the hydraulic pump from which hydraulic oil is sucked when the first actuator or the second actuator contracts, to the oil tank; The hydraulic actuator drive device according to claim 1 .

3. 2. The hydraulic actuator drive device according to claim 1, wherein the first actuator is made up of a plurality of first actuators, and / or the second actuator is made up of a plurality of second actuators.

4. the first actuator is used in the bed of a winged vehicle to open and close one of a pair of left and right wings swingably supported on a fixed frame, the second actuator is used to open and close the other of the pair of left and right wings; The hydraulic actuator drive device according to any one of claims 1 to 3.

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