Fluid supply and discharge device

Abstract

This prevents the pressurized working fluid from flowing back into the working chamber of the fluid supply and discharge device. [Solution] The pressurized oil supply and discharge device (2) comprises a piston member (5), an operating chamber (9) through which hydraulic fluid (F) is supplied and discharged by the movement of the piston member (5), and a check valve (12) provided in a supply and discharge passage (25) communicating with the operating chamber (9). The piston member (5) has a valve operating part (55) that opens the check valve (12) according to the axial position of the piston member (5).

Description

Technical Field

[0002]

[0001] The present disclosure relates to a fluid supply and discharge device that supplies and discharges a working fluid to and from a cylinder device.

Background Art

[0002] Conventionally, in order to fix a workpiece, a clamp device (cylinder device) is known in which a locked state or a released state is switched by a working fluid supplied to and discharged from a working chamber. This type of clamp device can be used together with a fluid supply and discharge device that supplies and discharges a working fluid to and from the clamp device (Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the conventional technology, for example, when an external force as a large reaction force acts on the clamp device, the pressurized working fluid may flow backward into the working chamber of the fluid supply and discharge device and push back the piston member. In this case, after the reaction force no longer acts on the clamp device, a pressure drop of the working fluid occurs by the amount by which the piston member is pushed back, and there is a possibility that the clamping force of the clamp device becomes insufficient.

[0005] One aspect of the present disclosure aims to prevent the pressurized working fluid from flowing backward into the working chamber of the fluid supply and discharge device.

Means for Solving the Problems

[0006] ​​​ The fluid supply and discharge devices (pressure oil supply and discharge devices) 2, 2A, and 2B each include a housing 10, a piston member 5 inserted into the housing 10 so as to be movable in the axial direction, an operating chamber 9 through which working fluid (hydraulic oil) F is supplied and discharged by the axial movement of the piston member 5, a supply and discharge passage 25 provided in the housing 10 in communication with the operating chamber 9 and through which the working fluid F passes, and check valves 12 and 12B arranged in the supply and discharge passage 25 in a direction that restricts the flow of working fluid F supplied to the operating chamber 9. The piston member 5 has a valve operating part (55) that opens the check valves 12 and 12B according to the axial position of the piston member 5.

[0008] One aspect of this disclosure, configured as described above, produces the following effects. In the fluid supply and discharge device of this disclosure, a check valve is positioned in the supply and discharge passage in a direction that restricts the flow of working fluid supplied to the working chamber. Therefore, when the check valve is closed, working fluid is not supplied to the working chamber. As a result, even if the working fluid is excessively pressurized on the side of an external device (e.g., a cylinder device) connected to the fluid supply and discharge device, the excessively pressurized working fluid is not supplied to the working chamber through the supply and discharge passage. Consequently, it is possible to prevent the pressurized working fluid from flowing back into the working chamber of the fluid supply and discharge device.

[0009] Furthermore, the piston member has a valve operating section that opens a check valve according to the axial position of the piston member. Therefore, it is possible to open the check valve when the piston member moves to a desired axial position, and the timing of the supply of working fluid to the working chamber can be controlled.

[0010] The above disclosure is preferably further enhanced by the following configurations (1) to (4).

[0011] (1) For example, as shown in Figures 1 to 10, the piston member 5 is a bottomed cylindrical shape having a guide hole 53 inside the piston member 5, and further comprises a screw shaft 6 inserted into the guide hole 53, and a ball nut 7 that moves the piston member 5 in the axial direction as the screw shaft 6 rotates. In this case, since a ball screw is provided as the mechanism for moving the piston member in the axial direction, the force required to rotate the piston member in the axial direction using, for example, a rotational force transmission tool is reduced compared to conventional sliding screws. As a result, the operability of the fluid supply and discharge device is improved.

[0012] (2) For example, as shown in Figures 2, 7, and 10, the piston member 5 moves between a first stroke end on one axial end and a second stroke end on the other axial end, and the valve operating unit 55 opens the check valves 12 and 12B when the piston member 5 moves to the first stroke end or the second stroke end. In this case, when the piston member moves to the position of the first stroke end or the second stroke end, the valve operating unit can open the check valve and start supplying working fluid to the working chamber.

[0013] (3) For example, as shown in Figures 2, 7, and 10, the valve operating part 55 is provided on the outer circumferential surface of the piston member 5, and when the piston member 5 moves to the first stroke end or the second stroke end, the valve operating part 55 presses the valve bodies 121 and 121B of the check valves 12 and 12B to open the check valve 12. In this case, a valve operating section that operates the check valve according to the axial position of the piston member can be suitably provided on the piston member. Furthermore, by changing the axial position of the valve operating section on the piston member, the timing of the supply of working fluid to the working chamber can be controlled.

[0014] (4) For example, as shown in Figures 8 to 10, the supply and discharge passage 25 includes a discharge passage 25A through which the working fluid F discharged from the working chamber 9 passes, and a supply passage 25B through which the working fluid F supplied to the working chamber 9 passes, and the valve operating unit 55 opens a check valve (second check valve) 12B provided in the supply passage 25B. In this case, since a check valve is arranged in the supply passage for supplying the working fluid to the working chamber, it is possible to prevent the working fluid with excessive pressure from being supplied to the working chamber through the supply passage. Further, when the piston member moves to a desired position in the axial direction, it becomes possible to open the check valve, and the timing of supplying the working fluid to the working chamber can be controlled.

Advantages of the Invention

[0015] According to one aspect of the present disclosure, it is possible to prevent the pressurized working fluid from flowing back into the working chamber of the fluid supply and discharge device.

Brief Description of the Drawings

[0016] [Figure 1] It is a cross-sectional view showing a main part of a hydraulic cylinder unit according to Embodiment 1. [Figure 2] It is a cross-sectional view showing a state (decompression state) where the piston member of the pressure oil supply and discharge device is at the stroke retracted end. [Figure 3] It is a cross-sectional view showing a state where the piston member shown in FIG. 2 is at the stroke intermediate position. [Figure 4] It is a cross-sectional view showing a state (compression state) where the piston member shown in FIG. 2 is at the stroke advanced position. [Figure 5] It is a cross-sectional view showing a main part of a hydraulic cylinder unit according to Embodiment 2, and shows a state (compression state) where the piston member of the pressure oil supply and discharge device is at the stroke retracted end. [Figure 6] It is a cross-sectional view showing a state where the piston member shown in FIG. 5 is at the stroke intermediate position. [Figure 7] It is a cross-sectional view showing a state (decompression state) where the piston member shown in FIG. 5 is at the stroke advanced position. [Figure 8] It is a cross-sectional view showing a main part of a hydraulic cylinder unit according to Embodiment 3, and shows a state (compression state) where the piston member of the pressure oil supply and discharge device is at the stroke retracted end. [Figure 9] It is a cross-sectional view showing a state where the piston member shown in FIG. 8 is at the stroke intermediate position. [Figure 10] It is a cross-sectional view showing the state (pressure reduction state) where the piston member shown in FIG. 8 is in the stroke advanced position.

Mode for Carrying Out the Invention

[0017] 〔Embodiment 1〕 Hereinafter, an embodiment of the present disclosure will be described. Hereinafter, an example of a hydraulic cylinder unit provided with a fluid supply / discharge device according to the present invention will be described. Note that the following description is an example of the fluid supply / discharge device according to the present invention, and the technical scope of the present invention is not limited to the illustrated example.

[0018] [Configuration of Hydraulic Cylinder Unit 1] FIG. 1 is a cross-sectional view showing a main part of a hydraulic cylinder unit 1 according to the present embodiment. As shown in FIG. 1, the hydraulic cylinder unit 1 includes a pressure oil supply / discharge device (fluid supply / discharge device) 2, and a plurality of cylinder devices 3 to which hydraulic oil (operating fluid) F is supplied from the pressure oil supply / discharge device 2 and which discharge the hydraulic oil F to the pressure oil supply / discharge device 2. Further, the hydraulic cylinder unit 1 is disposed in a fluid passage 11 connecting the pressure oil supply / discharge device 2 and each cylinder device 3, and includes a pressure reducing device 4 that restricts the flow of the hydraulic oil F supplied from the pressure oil supply / discharge device 2 to the cylinder device 3 when the pressure on the cylinder device 3 side reaches a predetermined value.

[0019] In the hydraulic cylinder unit 1, the hydraulic oil F discharged from the pressure oil supply / discharge device 2 flows into the fluid passage 11 and is supplied to the cylinder device 3 via the pressure reducing device 4. Further, the hydraulic oil F discharged from the cylinder device 3 flows into the fluid passage 11 and is supplied to the pressure oil supply / discharge device 2 via the pressure reducing device 4. These pressure oil supply / discharge device 2, cylinder device 3, and pressure reducing device 4 may be provided on, for example, a plate-shaped conveying member (not shown) configured to be movable along a track.

[0020] In the example shown in Figure 1, the pressurized oil supply and discharge device 2 is positioned so that the axial direction, which is the direction in which the piston member 5 moves, is horizontal. In the following description, the direction in which the bottomed cylindrical piston member 5 of the pressurized oil supply and discharge device 2 moves will be referred to as the left-right direction (axial direction), and the side of the piston member 5 with the bottom 54 will be referred to as the left side, and the side opposite the bottom 54 will be referred to as the right side. However, the pressurized oil supply and discharge device 2 may also be positioned so that the axial direction is vertical.

[0021] (Pressurized oil supply and discharge device) The pressurized oil supply and discharge device 2 comprises a hollow housing 10, a bottomed cylindrical piston member 5 inserted into the housing 10 so as to be movable in the axial direction, a screw shaft 6 inserted inside the piston member 5, and a ball nut 7 that moves the piston member 5 in the axial direction as the screw shaft 6 rotates (rotates) around its axis.

[0022] Furthermore, the pressurized oil supply and discharge device 2 includes a cap member 8 connected to the base end (axial right end) opposite to the tip end (axial left end) which is the threaded end of the screw shaft 6, and which transmits rotational force in the direction of the axis to the screw shaft 6, and an operating chamber 9 through which hydraulic fluid F is supplied and discharged (supplied and discharged) by the axial movement of the piston member 5.

[0023] Furthermore, the pressurized oil supply and discharge device 2 includes a supply and discharge passage 25 provided in the housing 10 in communication with the working chamber 9 and through which the hydraulic oil F passes, and a check valve 12 provided in the supply and discharge passage 25 in a direction that restricts the flow of hydraulic oil F supplied to the working chamber 9.

[0024] The cap member 8 is a cylindrical member connected to the base end of the screw shaft 6 by a bolt 21. As the cap member 8 rotates in the direction of its axis, the screw shaft 6 rotates in conjunction with it.

[0025] The cap member 8 has an operating portion 81 for receiving rotational force in the direction of the axis. This operating portion 81 has a polygonal protrusion that fits into a recess formed in a rotational force transmission tool T (see Figure 2) for transmitting rotational force to the cap member 8.

[0026] Furthermore, the cap member 8 has an insertion hole 82 into which the non-threaded portion at the base end of the screw shaft 6 is inserted, and a guide groove 83 formed axially on the inner circumferential surface of the insertion hole 82. A parallel pin 22 that engages with the guide groove 83 is provided between the inner circumferential surface of the insertion hole 82 and the outer circumferential surface of the screw shaft 6. In addition, a sliding groove 84 is formed circumferentially on the outer circumferential surface of the cap member 8, which is positioned inside the housing 10. Multiple bearings (ball members) 23 are mounted in this sliding groove 84.

[0027] The piston member 5 is a bottomed cylindrical member having a bottom 54 at its axial left end. The piston member 5 is tightly fitted into the housing 10 so as to be movable in the axial direction. The piston member 5 has a guide hole 53 formed axially inside it. A screw shaft 6 can be inserted into this guide hole 53. The piston member 5 also has a housing hole 51 on the opening 5A side (axial right side) opposite to the bottom 54, which has a larger diameter than the guide hole 53. A ball nut 7 is fixed to the inner circumferential surface (inner circumferential wall) of this housing hole 51. A parallel pin 24 that engages with a guide groove 52 is provided between the inner circumferential surface of the housing hole 51 and the outer circumferential surface of the ball nut 7.

[0028] The screw shaft 6 has threads formed on its outer circumferential surface for screwing into the ball nut 7. The ball nut 7 includes a nut 71 and a plurality of ball members 72 arranged in grooves on the inner circumferential surface of the nut 71. The nut 71 is provided on the outer circumferential surface of the screw shaft 6 via the ball members 72 so as to be movable in the axial direction.

[0029] The screw shaft 6 and the ball nut 7 constitute a ball screw, which is a mechanism for moving the piston member 5 in the axial direction. The rotation of the screw shaft 6 causes the ball nut 7 to move axially along the screw shaft 6. This movement of the ball nut 7 causes the piston member 5 to move axially.

[0030] The check valve 12 is installed in the supply and discharge passage 25 in a manner that allows the flow of hydraulic fluid F discharged from the working chamber 9 and restricts the flow of hydraulic fluid F supplied to the working chamber 9. The check valve 12 has a ball-shaped valve body 121, a valve seat 122 with an opening in the center, and a biasing spring 123 that biases the valve body 121. The valve body 121 is biased toward the valve seat 122 by the biasing spring 123. The check valve 12 closes when the valve body 121 seats on the valve seat 122, thereby restricting the flow of hydraulic fluid F supplied to the working chamber 9. When the valve body 121 is seated on the valve seat 122, a part of it is positioned (protruding) into the working chamber 9.

[0031] The piston member 5 has a valve operating section 55 that operates the check valve 12. The valve operating section 55 contacts the valve body 121 as the piston member 5 moves in the axial direction, thereby opening the check valve 12 (see Figure 2).

[0032] In this embodiment, the valve operating section 55 is provided on the outer circumferential surface near the bottom 54 of the piston member 5. This valve operating section 55 is formed, for example, by providing a groove (notch) 56 on the outer circumferential surface of the piston member 5. The groove 56 is provided axially along the outer circumferential surface of the piston member 5 on the check valve 12 side, thereby creating an axially extending gap between the inner circumferential surface of the working chamber 9 and the groove 56. A part of the valve body 121 of the check valve 12 is positioned in this gap so as to protrude from the inner circumferential surface of the working chamber 9. In other words, the check valve 12 is positioned in the supply and discharge passage 25 such that a part of the valve body 121 is located on the movement path of the piston member 5 (valve operating section 55) within the working chamber 9. Therefore, as the piston member 5 moves axially, the valve operating section 55 comes into contact with the valve body 121, and the check valve 12 opens when the valve operating section 55 pushes the valve body 121.

[0033] The valve operating portion 55 may be formed integrally with or separately from the piston member 5, on the outer circumferential surface of the piston member 5 on the bottom 54 side, so as to protrude radially outward from the piston member 5. In this case, the groove 56 can be omitted.

[0034] In the pressurized oil supply and discharge device 2, the working chamber 9 is formed on the opposite side (axial left) from the cap member 8 relative to the piston member 5. Therefore, when the piston member 5 moves axially to the left, the hydraulic fluid F in the working chamber 9 is compressed. The compressed hydraulic fluid F pushes the valve body 121 against the biasing force of the biasing spring 123, causing the valve body 121 to separate from the valve seat 122 and the check valve 12 to open. As a result, the hydraulic fluid F in the working chamber 9 is discharged through the supply and discharge passage 25 and supplied to the cylinder device 3.

[0035] On the other hand, when the piston member 5 moves to the right in the axial direction, the pressure inside the working chamber 9 is reduced. As a result, a pressure difference is created between the working chamber 9 side and the fluid passage 11 side, with the check valve 12 in between. With this pressure difference present, the valve operating part 55 of the piston member 5 contacts the valve body 121 and pushes the valve body 121 against the biasing force of the biasing spring 123, causing the valve body 121 to separate from the valve seat 122 and the check valve 12 to open. As a result, the hydraulic fluid F discharged from the cylinder device 3 is supplied to the working chamber 9 through the supply and discharge passage 25.

[0036] (Cylinder device) The cylinder device 3 is a device that operates using hydraulic fluid F. The cylinder device 3 may also be, for example, a clamping device whose locked state or released state is switched by the hydraulic fluid F.

[0037] The cylinder device 3 comprises a hollow housing 30, a piston member 31 inserted into the housing 30 so as to be movable in the axial direction (up and down), an output rod 32 protruding from the upper part of the piston member 31, and an operating chamber 33 located axially above the piston member 31 (on the output rod 32 side). The cylinder device 3 also comprises a spring chamber 34 located on the opposite side of the piston member 31 from the operating chamber 33, i.e., axially below the piston member 31, and a biasing spring 35 mounted in the spring chamber 34 that biases the piston member 31 toward the operating chamber 33. The operating chamber 33 is in communication with a fluid passage 11, and hydraulic fluid F is supplied to and discharged from the operating chamber 33 through this fluid passage 11.

[0038] When hydraulic fluid F is supplied to the cylinder device 3 through the fluid passage 11, the pressing force based on the hydraulic fluid F supplied to the working chamber 33 moves the piston member 31 toward the biasing spring 35, i.e., downward in the axial direction, against the biasing force of the biasing spring 35. On the other hand, when the hydraulic fluid F is discharged from the cylinder device 3 through the fluid passage 11, the pressing force based on the hydraulic fluid F in the working chamber 33 decreases, and the biasing force of the biasing spring 35 moves the piston member 31 upward in the axial direction.

[0039] Furthermore, the hydraulic cylinder unit 1 only needs to be equipped with one or more cylinder devices 3. Also, the cylinder device 3 can be any device that operates using hydraulic fluid F, and is not limited to clamping devices.

[0040] (Depressurization device) The pressure reducing device 4 is a device that, when hydraulic fluid F is supplied from the pressurized oil supply and discharge device 2 to the cylinder device 3, closes its valve when the pressure on the cylinder device 3 side reaches a predetermined value, thereby limiting the supply of hydraulic fluid F from the pressurized oil supply and discharge device 2 to the cylinder device 3. By keeping the pressure on the cylinder device 3 side (secondary side) lower (a predetermined value) than the pressure on the pressurized oil supply and discharge device 2 side (primary side) with the pressure reducing device 4, it is possible to reduce damage to the cylinder device 3 due to excessive supply of hydraulic fluid F, for example.

[0041] Specifically, when the pressure on the cylinder device 3 side is below a predetermined value, the pressure reducing device 4 is open. As a result, the supply of hydraulic fluid F from the pressurized oil supply and discharge device 2 side to the cylinder device 3 side is not restricted, and the pressure on the cylinder device 3 side gradually increases in accordance with the amount of hydraulic fluid F supplied. When the cylinder device 3 side reaches the predetermined pressure, the pressure reducing device 4 closes. This restricts the supply of hydraulic fluid F from the pressurized oil supply and discharge device 2 side to the cylinder device 3 side, and the pressure on the cylinder device 3 side is kept constant.

[0042] In this way, the cylinder device 3 can be protected by placing the pressure reducing device 4 between the pressurized oil supply and discharge device 2 and the cylinder device 3. However, the pressure reducing device 4 is not mandatory and can be omitted. In this case, the pressurized oil supply and discharge device 2 and the cylinder device 3 can be directly connected by the fluid passage 11 without going through the pressure reducing device 4.

[0043] [Operation of hydraulic cylinder unit 1] Next, an example of the operation of the hydraulic cylinder unit 1 will be described. Figures 2 to 4 are cross-sectional views showing an example of the operation of the hydraulic cylinder unit 1. Figure 2 shows the state in which the piston member 5 of the pressurized oil supply and discharge device 2 is at the stroke retraction end (first stroke end) on the axial right side (depressurized state). Figure 3 shows the state in which the piston member 5 is at the intermediate stroke position. Figure 4 shows the state in which the piston member 5 is at the stroke advance end (second stroke end) (compressed state).

[0044] The piston member 5 moves between the stroke retraction end on the axial right side (see Figure 2) and the stroke advancement end on the axial left side (see Figure 4). The pressurized oil supply and discharge device 2 supplies hydraulic fluid F to the cylinder device 3 when the piston member 5 moves from the stroke retraction end to the stroke advancement position. The pressurized oil supply and discharge device 2 also discharges the hydraulic fluid F from the cylinder device 3 when the piston member 5 moves from the stroke advancement position to the stroke retraction end.

[0045] As shown in Figure 2, when the piston member 5 of the pressurized oil supply and discharge device 2 is at its stroke retracted end on the axial right side, the ball nut 7 is on the base end side of the screw shaft 6, and the piston member 5 is located near the cap member 8. At this time, the valve operating portion 55 of the piston member 5 pushes the valve body 121 against the biasing force of the biasing spring 123, causing the check valve 12 to open.

[0046] In this initial state, the recess formed at the tip of the rotational force transmission tool T, which transmits rotational force to the cap member 8, is first fitted into the operating portion 81 of the cap member 8. Then, when the rotational force transmission tool T is rotated in a first direction around its axis by an operator or robot, the cap member 8 fitted into the recess of the rotational force transmission tool T transmits rotational force to the screw shaft 6. As the screw shaft 6 rotates due to this rotational force, the ball nut 7 that is screwed onto the screw shaft 6 moves to the left in the axial direction, and the piston member 5 fixed to the ball nut 7 moves to the left in the axial direction so as to move away from the cap member 8.

[0047] As the piston member 5 moves axially to the left, the valve operating part 55 separates from the valve body 121 of the check valve 12, and the hydraulic fluid F, pressurized by the piston member 5, pushes the valve body 121 against the biasing force of the biasing spring 123, thereby maintaining the valve body 121 in the open state. As a result, the hydraulic fluid F in the working chamber 9 is supplied to the cylinder device 3 through the supply and discharge passage 25. As the hydraulic fluid F is supplied to the working chamber 33 of the cylinder device 3, a pressing force corresponding to the hydraulic fluid F supplied to the working chamber 33 acts to move the piston member 31 axially downward.

[0048] Next, as shown in Figure 4, when the piston member 5 is moved to the forward stroke end, the piston member 31 of the cylinder device 3 moves to the lower stroke end, and the cylinder device 3 locks into place. When the pressure on the cylinder device 3 side reaches a predetermined value, the pressure reducing device 4 closes. This restricts the supply of hydraulic fluid F from the pressurized oil supply and discharge device 2 side to the cylinder device 3 side, keeping the pressure on the cylinder device 3 side lower than the pressure on the pressurized oil supply and discharge device 2 side.

[0049] When the pressure reducing device 4 closes, the pressure in the pressurized oil supply and discharge device 2 becomes balanced between the working chamber 9 side and the fluid passage 11 side, with the check valve 12 in between. In other words, there is no pressure difference between the working chamber 9 side and the fluid passage 11 side. As a result, the biasing force of the biasing spring 123 moves the valve body 121 toward the valve seat 122 side, and the check valve 12 closes.

[0050] Here, in the compressed state of the hydraulic fluid F as shown in Figure 4, if a large external force acting as a reaction force acts on the cylinder device 3, for example, the excessively pressurized hydraulic fluid F may flow back into the working chamber 9 of the pressurized oil supply and discharge device 2 and push back the piston member 5. In this case, after the reaction force no longer acts on the cylinder device 3, a pressure drop in the hydraulic fluid F occurs by the amount the piston member 5 was pushed back, which could result in insufficient clamping force for the cylinder device 3. For this reason, in conventional pressurized oil supply and discharge devices, it was necessary to use a sliding screw (trapezoidal screw) with a relatively large frictional force between the screw shaft and the nut as a mechanism to move the piston member 5 in the axial direction, so as not to push back the piston member 5 by the hydraulic fluid F that has flowed back into the working chamber 9.

[0051] In contrast, in the pressurized oil supply and discharge device 2 of this disclosure, a check valve 12 is arranged in the supply and discharge passage 25, so that even if the hydraulic fluid F on the cylinder device 3 side becomes excessively pressurized, the excessively pressurized hydraulic fluid F is not supplied to the working chamber 9. Therefore, with the pressurized oil supply and discharge device 2, the excessively pressurized hydraulic fluid F does not flow back into the working chamber 9, and the pressure inside the working chamber 9 is maintained, thus reliably preventing the aforementioned deficiency of clamping force. In addition, in the pressurized oil supply and discharge device 2, the piston member 5 is not pushed back by the hydraulic fluid F that has flowed back into the working chamber 9, so it is possible to use a ball screw, which has a lower frictional force compared to a conventional sliding screw, as the mechanism for moving the piston member 5 in the axial direction. As a result, the force required to rotate the cap member 8 by the rotational force transmission tool T is reduced, and the operability of the pressurized oil supply and discharge device 2 can be improved.

[0052] Next, with the piston member 5 at the stroke forward end, when the rotational force transmission tool T rotates in a second direction opposite to the first direction around the axis, the piston member 5 moves axially to the right so as to approach the cap member 8. At this time, the hydraulic fluid F in the working chamber 9 is depressurized, creating a pressure difference between the working chamber 9 side and the fluid passage 11 side with the check valve 12 in between. As a result, in addition to the biasing force of the biasing spring 123, the valve body 121 is pushed toward the valve seat 122 side by the pressing force due to the aforementioned pressure difference, and the check valve 12 maintains a closed state.

[0053] Then, as the piston member 5 moves further to the right axially and returns to its stroke retraction end, the valve operating part 55 contacts the valve body 121 and pushes the valve body 121 against the biasing force of the biasing spring 123 and the pressing force due to the aforementioned pressure difference, thereby opening the check valve 12. As a result, the hydraulic fluid F is supplied to the working chamber 9 through the supply and discharge passage 25, and the pressurized oil supply and discharge device 2 returns to the initial state shown in Figure 2.

[0054] [Summary of Pressurized Oil Supply and Discharge System 2] As described above, the pressurized oil supply and discharge device 2 according to this embodiment includes a housing 10, a piston member 5 inserted into the housing 10 so as to be movable in the axial direction, an operating chamber 9 through which hydraulic fluid F is supplied and discharged by the axial movement of the piston member 5, a supply and discharge passage 25 provided in the housing 10 and communicating with the operating chamber through which the hydraulic fluid F passes, and a check valve 12 positioned in the supply and discharge passage 25 in a direction that restricts the flow of hydraulic fluid F supplied to the operating chamber 9. The piston member 5 has a valve operating part 55 that opens the check valve 12 according to the axial position of the piston member 5.

[0055] In the pressurized oil supply and discharge device 2, a check valve 12 is positioned in the supply and discharge passage 25 in a direction that restricts the flow of hydraulic fluid F supplied to the working chamber 9. Therefore, when the check valve 12 is closed, hydraulic fluid F is not supplied to the working chamber 9. As a result, even if the hydraulic fluid F is excessively pressurized on the cylinder device 3 side, the excessively pressurized hydraulic fluid F is not supplied to the working chamber 9 through the supply and discharge passage 25. Consequently, it is possible to prevent the pressurized hydraulic fluid F from flowing back into the working chamber 9 of the pressurized oil supply and discharge device 2.

[0056] Furthermore, the piston member 5 has a valve operating section 55 that opens the check valve 12 according to the axial position of the piston member 5. Therefore, the check valve 12 can be opened when the piston member 5 moves to a desired axial position, and the timing of the supply of hydraulic fluid F to the working chamber 9 can be controlled.

[0057] [Embodiment 2] Other embodiments of this disclosure are described below. For the sake of convenience, components having the same function as those described in the above embodiments are denoted by the same reference numerals, and their descriptions are not repeated.

[0058] The hydraulic cylinder unit 1A according to this embodiment differs from the hydraulic cylinder unit 1 described above mainly in that it includes a pressurized oil supply and discharge device 2A in which an operating chamber 9 is formed on the side of the cap member 8 (right side in the axial direction) relative to the piston member 5.

[0059] [Configuration of Hydraulic Cylinder Unit 1A] Figure 5 is a cross-sectional view showing the piston member 5 of the pressurized oil supply and discharge device 2A in the retracted stroke position. Figure 6 is a cross-sectional view showing the piston member 5 shown in Figure 5 moved to the intermediate stroke position. Figure 7 is a cross-sectional view showing the piston member shown in Figure 5 moved to the advanced stroke position.

[0060] As shown in Figures 5 to 7, in the pressurized oil supply and discharge device 2A, an operating chamber 9 is formed on the side of the piston member 5 that is on the cap member 8 side (right side in the axial direction), and the housing hole 51 and guide hole 53 of the piston member 5 function as part of the operating chamber 9. On the other hand, the side of the piston member 5 opposite to the cap member 8 side (left side in the axial direction) is an air chamber 57. The housing 10 is provided with a breathing hole 58 for supplying and discharging air from the air chamber 57 to the outside in accordance with the axial movement of the piston member 5. In addition, the screw shaft 6 is provided with an internal passage 61 that extends in the axial direction of the screw shaft 6. Through this internal passage 61, the hydraulic fluid F can move inside the screw shaft 6 and into the operating chamber 9.

[0061] In the pressurized oil supply and discharge device 2A, the valve operating section 55 is provided on the outer circumferential surface near the opening 5A on the opposite side (axial right side) from the bottom 54 of the piston member 5. When the piston member 5 is at the stroke forward end on the axial left side, the valve operating section 55 pushes the valve body 121, causing the check valve 12 to open (see Figure 7).

[0062] In the pressurized oil supply and discharge device 2A, when the piston member 5 moves to the right in the axial direction, the hydraulic fluid F in the working chamber 9 is compressed. The compressed hydraulic fluid F pushes the valve body 121 against the biasing force of the biasing spring 123, causing the valve body 121 to separate from the valve seat 122 and the check valve 12 to open. As a result, the hydraulic fluid F in the working chamber 9 is discharged through the supply and discharge passage 25 and supplied to the cylinder device 3.

[0063] On the other hand, when the piston member 5 moves axially to the left, the pressure inside the working chamber 9 is reduced. As a result, a pressure difference is created between the working chamber 9 side and the fluid passage 11 side, with the check valve 12 in between. With this pressure difference present, the valve operating part 55 of the piston member 5 contacts the valve body 121 and pushes the valve body 121 against the biasing force of the biasing spring 123, causing the valve body 121 to separate from the valve seat 122 and the check valve 12 to open. As a result, the hydraulic fluid F discharged from the cylinder device 3 is supplied to the working chamber 9 through the supply and discharge passage 25.

[0064] [Operation of Hydraulic Cylinder Unit 1A] Next, an example of the operation of the hydraulic cylinder unit 1A will be described. As shown in Figure 5, in the hydraulic cylinder unit 1A, when the piston member 5 is at the stroke retracted end, compressed hydraulic fluid F is supplied to the cylinder device 3, and the cylinder device 3 is in a locked state. At this time, the check valve 12 is closed because the valve body 121 is biased toward the valve seat 122 by the biasing force of the biasing spring 123.

[0065] Next, as shown in Figure 6, when the piston member 5 moves axially to the left from the stroke retraction end to the stroke intermediate position, the pressure inside the working chamber 9 is reduced, and a pressure difference is created between the working chamber 9 side and the fluid passage 11 side with the check valve 12 in between. As a result, the check valve 12 remains closed, and the hydraulic fluid F is not supplied to the working chamber 9.

[0066] Next, as shown in Figure 7, when the piston member 5 moves further axially to the left from the intermediate stroke position to the forward stroke end, the valve operating part 55 comes into contact with the valve body 121, pushing the valve body 121 away from the valve seat 122. As a result, the check valve 12 opens, and the hydraulic fluid F is supplied to the working chamber 9 through the supply and discharge passage 25.

[0067] [Summary of Pressurized Oil Supply and Discharge System 2A] As described above, in this embodiment, the pressurized oil supply and discharge device 2A compresses the hydraulic fluid F by moving the piston member 5 toward the stroke retraction end and discharges the hydraulic fluid F, and when the piston member 5 is at the stroke retraction end, the check valve 12 is closed.

[0068] In the pressurized oil supply and discharge device 2A, even if the hydraulic fluid F is excessively pressurized on the cylinder device 3 side, the excessively pressurized hydraulic fluid F is not supplied to the working chamber 9 through the supply and discharge passage 25. Therefore, it is possible to prevent the excessively pressurized hydraulic fluid F from flowing back into the working chamber 9 of the pressurized oil supply and discharge device 2A.

[0069] [Embodiment 3] Other embodiments of this disclosure are described below. For the sake of convenience, components having the same function as those described in the above embodiments are denoted by the same reference numerals, and their descriptions are not repeated.

[0070] The hydraulic cylinder unit 1B according to this embodiment differs from the hydraulic cylinder unit 1A described above mainly in that it includes a pressurized oil supply and discharge device 2B which includes a discharge passage 25A through which the hydraulic oil F discharged from the working chamber 9 passes, and a supply passage 25B through which the hydraulic oil F supplied to the working chamber 9 passes.

[0071] [Configuration of Hydraulic Cylinder Unit 1B] Figure 8 is a cross-sectional view showing the piston member 5 of the pressurized oil supply and discharge device 2B in the stroke retracted end position (compression state). Figure 9 is a cross-sectional view showing the piston member 5 shown in Figure 8 in the stroke intermediate position. Figure 10 is a cross-sectional view showing the piston member shown in Figure 8 in the stroke advanced position (depressurization state).

[0072] As shown in Figures 8 to 10, in the pressurized oil supply and discharge device 2B, the supply and discharge passage 25 includes a discharge passage 25A through which the hydraulic oil F discharged from the working chamber 9 passes, and a supply passage 25B through which the hydraulic oil F supplied to the working chamber 9 passes.

[0073] A first check valve 12A is provided in the discharge passage 25A in a manner that allows the flow of hydraulic fluid F discharged from the working chamber 9 and restricts the flow of hydraulic fluid F supplied to the working chamber 9. The first check valve 12A has a ball-shaped first valve body 121A, a first valve seat 122A with an opening in the center, and a first biasing spring 123A that biases the first valve body 121A. The first valve body 121A is biased toward the first valve seat 122A by the first biasing spring 123A. The first check valve 12A closes when the first valve body 121A seats on the first valve seat 122A, restricting the flow of hydraulic fluid F supplied to the working chamber 9 through the discharge passage 25A.

[0074] A second check valve (non-return valve) 12B is provided in the supply passage 25B in a manner that allows the flow of hydraulic fluid F discharged from the working chamber 9 and restricts the flow of hydraulic fluid F supplied to the working chamber 9. The second check valve 12B includes a ball-shaped second valve body 121B, a second valve seat 122B with an opening in the center, a second biasing spring 123B that biases the second valve body 121B, and a rod-shaped pressing member 124 connected to the second valve body 121B. The second valve body 121B is biased toward the second valve seat 122B by the second biasing spring 123B. The second check valve 12B closes when the second valve body 121B seats on the second valve seat 122B, restricting the flow of hydraulic fluid F supplied to the working chamber 9 through the supply passage 25B.

[0075] The pressing member 124 is positioned within a communication passage 26 formed in the housing 10 to connect the working chamber 9 and the supply passage 25B. The pressing member 124 is tightly fitted into the communication passage 26 so that it can move in the axial direction of the pressing member 124.

[0076] The pressing member 124 has one end on the supply passage 25B side connected to the second valve body 121B. The pressing member 124 is positioned such that, when the second valve body 121B is seated on the valve seat 122, the other end on the operating chamber 9 side is positioned (protruding) inside the operating chamber 9. In other words, the second check valve 12B is positioned in the communication passage 26 such that a part of the pressing member 124 is located on the movement path of the piston member 5 (valve operating part 55) inside the operating chamber 9. As a result, the axial movement of the piston member 5 causes the valve operating part 55 to contact the pressing member 124, and by pushing the second valve body 121B via the pressing member 124, the second check valve 12B opens (see Figure 10).

[0077] [Operation of Hydraulic Cylinder Unit 1B] Next, an example of the operation of the hydraulic cylinder unit 1B will be described. As shown in Figure 8, in the hydraulic cylinder unit 1A, when the piston member 5 is at the stroke retracted end, compressed hydraulic fluid F is supplied to the cylinder device 3 mainly through the discharge passage 25A, and the cylinder device 3 is in a locked state. At this time, the first check valve 12A is closed because the biasing force of the first biasing spring 123A biases the first valve body 121A toward the first valve seat 122A. Similarly, the second check valve 12B is closed because the biasing force of the second biasing spring 123B biases the second valve body 121B toward the second valve seat 122B.

[0078] Next, as shown in Figure 9, when the piston member 5 moves axially to the left from the stroke retraction end to the stroke intermediate position, the pressure inside the working chamber 9 is reduced, and a pressure difference is created between the working chamber 9 side and the fluid passage 11 side in the discharge passage 25A, with the first check valve 12A in between. Similarly, in the supply passage 25B, a pressure difference is created between the supply passage 25B on the working chamber 9 side and the supply passage 25B on the fluid passage 11 side, with the second check valve 12B in between. As a result, the first check valve 12A and the second check valve 12B remain closed, preventing the hydraulic fluid F from being supplied to the working chamber 9.

[0079] Next, as shown in Figure 10, when the piston member 5 moves further axially to the left from the intermediate stroke position to the forward stroke end, the valve operating part 55 comes into contact with the pressing member 124, and the second valve body 121B is pushed away from the second valve seat 122B via the pressing member 124. As a result, the second check valve 12B opens, and the hydraulic fluid F flows through the supply passage 25B in the direction of arrow A in the figure, and the hydraulic fluid F is supplied to the working chamber 9.

[0080] [Summary of Pressurized Oil Supply and Discharge System 2B] As described above, in the pressurized oil supply and discharge device 2B according to this embodiment, the supply and discharge passage 25 includes a discharge passage 25A through which the hydraulic oil F discharged from the working chamber 9 passes, and a supply passage 25B through which the hydraulic oil F supplied to the working chamber 9 passes, and the valve operating unit 55 is configured to open the second check valve 12B provided in the supply passage 25B.

[0081] In the pressurized oil supply and discharge device 2B, a second check valve 12B is located in the supply passage 25B that supplies hydraulic fluid F to the working chamber 9. This prevents excessively pressurized hydraulic fluid F from being supplied to the working chamber 9 through the supply passage 25B. Therefore, it is possible to prevent excessively pressurized hydraulic fluid F from flowing back into the working chamber 9 of the pressurized oil supply and discharge device 2B.

[0082] In the embodiments described above, an example of a pressurized oil supply and discharge device that supplies hydraulic pressure to a cylinder device was given, but the disclosure is not limited thereto. For example, the disclosure can also be applied to an air supply and discharge device that supplies compressed air to a cylinder device instead of hydraulic pressure.

[0083] The present invention is not limited to the embodiments described above, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention. Furthermore, new technical features can be formed by combining the technical means disclosed in each embodiment. [Explanation of Symbols]

[0084] 1, 1A, 1B: Hydraulic cylinder unit 2, 2A, 2B: Pressure oil supply and discharge device (fluid supply and discharge device) 5: Piston member 6: Screw shaft 7: Ball nut 9: Working Room 12: Check valve 12B: Second check valve (check valve) 53: Guide hole 55; Valve operating section 71: Nut 72: Ball F: Hydraulic oil (working fluid)

Claims

1. Housing and A piston member is inserted into the housing so as to be movable in the axial direction, An operating chamber through which working fluid is supplied and discharged by the axial movement of the piston member, The housing is provided in communication with the working chamber and includes a supply and discharge passage for the working fluid, The system includes a check valve positioned in the supply and discharge passage in a manner that restricts the flow of the working fluid supplied to the working chamber, The piston member has a valve operating section that opens the check valve according to the axial position of the piston member, in a fluid supply and discharge device.

2. The piston member is a bottomed cylindrical shape with a guide hole inside the piston member, The screw shaft inserted into the guide hole, A ball nut moves the piston member in the axial direction as the screw shaft rotates, The fluid supply and discharge device according to claim 1, further comprising:

3. The piston member moves between a first stroke end on one axial end and a second stroke end on the other axial end. The fluid supply and discharge device according to claim 1 or 2, wherein the valve operating section opens the check valve when the piston member moves to the first stroke end or the second stroke end.

4. The valve operating section is provided on the outer circumferential surface of the piston member, The fluid supply and discharge device according to claim 3, wherein when the piston member moves to the first stroke end or the second stroke end, the valve operating part pushes the valve body of the check valve to open the check valve.

5. The aforementioned supply and discharge passage is A discharge passage through which the working fluid discharged from the working chamber passes, Includes a supply passage through which the working fluid supplied to the working chamber passes, The fluid supply and discharge device according to claim 1 or 2, wherein the valve operating unit opens the check valve provided in the supply passage.

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