Fluid supply and discharge device

Abstract

The present invention reduces the impact of accumulated grease so as to make the movement of a piston member more smooth.　This pressure-oil supply and discharge device (2) comprises: a closed-end cylindrical piston member (5); a female screw member (6) provided in the piston member (5); and a male screw member (7) that is inserted into a guide hole (53) of the piston member (5) and threadedly engages the female screw member (6) to move the piston member (5) in the axial direction, the male screw member (7) having an internal passage (70) that allows the passage of grease (G) applied to the male screw member (7).

Description

Fluid supply / drainage device

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

[0002] A fluid supply / discharge device is known that supplies and discharges hydraulic fluid to and from a clamping device (cylinder device) that is switched between a locked state and a released state by the hydraulic fluid. A conventional fluid supply / discharge device of this type is described in Patent Document 1. This conventional technology is configured as follows.

[0003] A conventional fluid supply / discharge device includes a female screw member provided on a cylindrical piston member with a bottom, a male screw member inserted into the piston member and threadedly engaging with the female screw member to move the piston member in the axial direction, and a working chamber into which working fluid is supplied and discharged as the piston member moves. As the male screw member rotates, the female screw member moves in the axial direction, thereby moving the piston member.

[0004] Japanese Patent Application Publication No. 2024-067886

[0005] In this type of fluid supply / discharge device, semi-solid grease (lubricant) is applied to the female and male threaded members to reduce wear at the threaded portions and ensure smooth operation. Grease tends to accumulate on the end of the male threaded member as the female threaded member moves back and forth in the axial direction, which can hinder the smooth movement of the piston member.

[0006] One aspect of the present disclosure aims to reduce the effects of grease accumulation and smooth the movement of a piston member.

[0007] In order to achieve the above object, the present disclosure provides a fluid supply and discharge device configured as follows, as shown in Figures 1 to 6, for example: The fluid supply and discharge device (pressure oil supply and discharge device) 2 includes a bottomed, cylindrical piston member 5 that is inserted into a housing 10 so as to be axially movably and has a guide hole 53 therein, a female screw member 6 provided on the piston member 5, a male screw member 7 that is inserted into the guide hole 53 and threadably engages with the female screw member 6 to move the piston member 5 in the axial direction, the male screw member 7 having an internal passage 70 through which grease G applied to the male screw member 7 passes, and a working chamber 9 to and from which working fluid F is supplied and discharged as the piston member 5 moves.

[0008] According to one aspect of the present disclosure, the influence of grease accumulation can be reduced, and the movement of the piston member can be made smoother.

[0009] Fig. 1 is a cross-sectional view showing a main part of a hydraulic cylinder unit according to an embodiment. Fig. 2 is a cross-sectional view showing an initial state in which a piston member of a pressure oil supply / discharge device is at an upper stroke end position. Fig. 3 is a cross-sectional view showing a state in which the piston member has moved from the upper stroke end position shown in Fig. 2 to a middle stroke position. Fig. 4 is a cross-sectional view showing a state in which the piston member has moved from the middle stroke position shown in Fig. 3 to a lower stroke end position. Fig. 5 is a cross-sectional view showing a state in which the piston member has moved from the lower stroke end position to the middle stroke position shown in Fig. 5.

[0010] An embodiment of the present disclosure will be described below. Note that the following description is an example of a fluid supply / drainage device according to the present disclosure, and the technical scope of the present disclosure is not limited to the illustrated example.

[0011] [Configuration of Hydraulic Cylinder Unit] Figure 1 is a cross-sectional view showing a main part of a hydraulic cylinder unit 1 according to this embodiment. As shown in Figure 1, the hydraulic cylinder unit 1 includes a pressure oil supply / discharge device (fluid supply / discharge device) 2, and a cylinder device 3 that receives a hydraulic oil (working fluid) F from the pressure oil supply / discharge device 2 and discharges the hydraulic oil F to the pressure oil supply / discharge device 2. The hydraulic cylinder unit 1 also includes a pressure accumulator 4 that is provided between the pressure oil supply / discharge device 2 and the cylinder device 3 and that maintains the hydraulic pressure of the hydraulic oil F in the event of a pressure drop (drop in hydraulic pressure) due to a leak of the hydraulic oil F, etc.

[0012] The pressure oil supply / discharge device 2 and the cylinder device 3 are in communication with each other via a pressure accumulator 4 and a fluid passage 11 through which hydraulic oil F passes. In this embodiment, the hydraulic oil F discharged from the pressure oil supply / discharge device 2 flows into the fluid passage 11 via the pressure accumulator 4, and is supplied to the cylinder device 3 through the fluid passage 11. Furthermore, 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 accumulator 4. The pressure oil supply / discharge device 2, the cylinder device 3, and the pressure accumulator 4 may be provided on a plate-shaped conveying member configured to be movable along a track, for example.

[0013] In the following description, the direction in which the bottomed cylindrical piston member 5 provided in the pressurized oil supply / discharge device 2 moves will be referred to as the up-down direction (axial direction), and the bottom 54 side of the piston member 5 in the up-down direction will be referred to as the lower side (lower part), and the side opposite the lower side will be referred to as the upper side (upper part), etc.

[0014] (Pressure Oil Supply and Discharge Device) The pressure oil supply and discharge device 2 comprises a hollow housing 10, a cylindrical piston member 5 with a bottom that is inserted into the housing 10 so as to be axially movably, a female screw member 6 provided in an accommodating hole 51 formed in the upper part of the piston member 5, and a male screw member 7 that screws into the female screw member 6. The pressure oil supply and discharge device 2 also comprises a cap member 8 that is connected to an upper end (base end) opposite to a lower end (tip end) that is the male threaded end of the male screw member 7, and that transmits a rotational force around the axis to the male screw member 7, and a working chamber 9 that is formed on the lower side (bottom 54 side) of the piston member 5 and into which hydraulic oil F is supplied and discharged as the piston member 5 moves.

[0015] The cap member 8 is a cylindrical member connected to the upper end of the male screw member 7 by a bolt 21. When the cap member 8 rotates around its axis, the male screw member 7 rotates.

[0016] The cap member 8 has an operating portion 81 at its top for receiving a rotational force around the axis. The operating portion 81 has a polygonal protrusion that fits into a recess formed in a rotational force transmission tool T (see FIG. 2) for transmitting a rotational force to the cap member 8.

[0017] The cap member 8 also has an insertion hole 82 into which the non-male-threaded portion on the upper end side of the male-threaded member 7 is inserted, and a guide groove 83 formed in the axial direction on the inner peripheral surface of the insertion hole 82. The insertion hole 82 is provided in the lower part of the cap member 8. A parallel pin 22 that engages with the guide groove 83 is provided between the inner peripheral surface of this insertion hole 82 and the outer peripheral surface of the male-threaded member 7. Furthermore, the cap member 8 has a sliding groove 84 formed in the circumferential direction on the lower part of its outer peripheral surface. A plurality of bearings (ball members) 23 are mounted in this sliding groove 84.

[0018] The piston member 5 is a bottomed, cylindrical member having a bottom 54 on the axially lower side. The piston member 5 is hermetically fitted into the housing 10 so as to be movable in the axial direction. The piston member 5 has a female thread member 6 provided on the upper part of its inner circumferential surface (inner circumferential wall). The piston member 5 also has a guide groove 52 formed in the axial direction on its outer circumferential surface (outer circumferential wall). A parallel pin 24 that engages with the guide groove 52 is provided between the outer circumferential surface of the piston member 5 and the housing 10. The piston member 5 also has a guide hole 53 formed therein into which the male thread member 7 can be inserted.

[0019] The female screw member 6 has a female screw formed on its inner peripheral surface. The male screw member 7 has a male screw formed on its outer peripheral surface that screws into the female screw. When the male screw member 7 rotates, the female screw member 6 moves up and down along the male screw member 7. As the female screw member 6 moves, the piston member 5 moves up and down.

[0020] As the piston member 5 moves up and down, the hydraulic oil F in the working chamber 9 is pressurized or depressurized, and the hydraulic oil F is supplied to and discharged from the cylinder device 3. For example, when the piston member 5 moves downward in the axial direction, the hydraulic oil F in the working chamber 9 is compressed. As a result, the hydraulic oil F is supplied to the cylinder device 3 through the supply and discharge path 25 provided in the housing 10. On the other hand, when the piston member 5 moves upward in the axial direction, the hydraulic oil F is depressurized. As a result, the hydraulic oil F is discharged from the cylinder device 3.

[0021] Here, semi-solid grease G is applied to the female screw member 6 and the male screw member 7 to reduce wear at the threaded portions and ensure smooth operation. If this grease G accumulates, for example, on the upper or lower part of the male screw member 7, it may interfere with smooth movement of the piston member 5, as will be described later. Therefore, in the pressure oil supply / discharge device 2, an internal passage 70 is formed in the male screw member 7 to allow the grease G to pass through.

[0022] In this embodiment, the internal passage 70 includes a first passage 71 that passes through the axial center of the male screw member 7 and opens at the lower end of the male screw member located on the bottom 54 side of the piston member 5, a second passage 72 that branches off from the first passage 71 and opens at the outer peripheral surface of the upper end side of the male screw member 7 located opposite the lower end, and a third passage 73 that branches off from the first passage 71 and opens at the outer peripheral surface of the lower end side of the second passage 72.

[0023] The first passage 71 is formed through the axial center of the male screw member 7 and communicates with a first opening 71A that opens at the lower end of the male screw member 7. The second passage 72 is formed radially from the first passage 71 and communicates with a second opening 72A that opens on the outer peripheral surface of the upper end side of the male screw member 7. The third passage 73 is formed radially from the first passage 71 and communicates with a third opening 73A that opens on the outer peripheral surface of the lower end side of the second opening 72A. Note that a plurality of second passages 72 and a plurality of third passages 73 may be provided in the male screw member 7.

[0024] The housing 10 also has an internal space S, separated from the operating chamber 9 by the piston member 5 hermetically fitted within the housing 10, in which the female screw member 6 and the male screw member 7 are disposed. This internal space S may be airtight to prevent air from entering or leaving. In other words, the housing 10 does not need to be provided with a breathing hole for discharging air from the internal space S, including the guide hole 53 of the piston member 5, to the outside or for introducing external air into the internal space S. This prevents grease G from scattering (leaking) to the outside through the breathing hole, thereby preventing a decrease in lubricity due to a decrease in grease G and an increase in drive resistance. Furthermore, this also prevents damage to components within the internal space S due to corrosion or wear caused by liquid, debris, etc. that has flowed into the internal space S from the outside.

[0025] (Cylinder Device) The cylinder device 3 is a device that is operated by hydraulic oil F. The cylinder device 3 may be, for example, a clamp device that is switched between a locked state and a released state by the hydraulic oil F.

[0026] The cylinder device 3 has 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 arranged below the piston member 31. The cylinder device 3 also has a spring chamber 34 arranged on the opposite side of the piston member 31 from the operating chamber 33, i.e., above the piston member 31, and a biasing spring 35 attached to the spring chamber 34 and biasing the piston member 31 toward the operating chamber 33. The operating chamber 33 is in communication with the fluid passage 11.

[0027] When hydraulic oil F is supplied to the cylinder device 3 through the fluid passage 11, the pressing force based on the hydraulic oil F supplied to the working chamber 33 moves the piston member 31 toward the output rod 32, i.e., axially upward, against the biasing force of the biasing spring 35. On the other hand, when the hydraulic oil F is discharged from the cylinder device 3 through the fluid passage 11, the pressing force based on the hydraulic oil F supplied to the working chamber 33 decreases, and the biasing force of the biasing spring 35 moves the piston member 31 axially downward.

[0028] It should be noted that the hydraulic cylinder unit 1 may be provided with a plurality of cylinder devices 3. Furthermore, the cylinder device 3 may be any device that is actuated by the hydraulic oil F, and is not limited to a clamp device.

[0029] (Pressure Accumulator) The pressure accumulator 4 is an accumulator connected to the pressure oil supply / discharge device 2. The pressure accumulator 4 includes a housing 40 having a pressure accumulator chamber 41 formed therein for storing hydraulic oil F, a pressure accumulator piston member 42 inserted into the housing 40 so as to be movable in the axial direction (up and down direction in the drawing), and a compression spring 43 which is an elastic member that biases the pressure accumulator piston member 42 toward the pressure accumulator chamber 41.

[0030] The housing 40 includes a first accommodating hole 40A and a second accommodating hole 40B having a larger diameter than the first accommodating hole 40A. A pressure accumulator piston member 42 is hermetically fitted into the first accommodating hole 40A so as to be movable in the axial direction. The pressure accumulator chamber 41 is disposed axially below the pressure accumulator piston member 42.

[0031] The accumulator chamber 41 communicates with the pressure oil supply and discharge device 2 via a first supply and discharge passage 44A provided in the housing 40. The accumulator chamber 41 also communicates with the fluid passage 11 via a second supply and discharge passage 44B provided in the housing 40. A sealing member 45 is provided in the circumferential direction on the inner peripheral surface of the first accommodating hole 40A that faces the outer peripheral surface of the accumulator piston member 42. The sealing member 45 is capable of hermetically engaging with the outer peripheral surface of the accumulator piston member 42.

[0032] The pressure accumulator 4 also includes an indicator rod 46 that is provided axially above the pressure accumulator piston member 42 and protrudes in the axial direction. The indicator rod 46 is housed in the second accommodating hole 40B. A spring chamber 47 that houses a compression spring 43 is formed between the outer circumferential surface of the indicator rod 46 and the inner circumferential surface of the second accommodating hole 40B. The compression spring 43 that urges the indicator rod 46 toward the pressure accumulator chamber 41 is disposed around the outer circumferential surface of the indicator rod 46 in the spring chamber 47. The indicator rod 46 has a flange on the end side that is connected to the pressure accumulator piston member 42, and the flange functions as a spring bearing 46A that receives the compression spring 43.

[0033] As will be described later, a tip 46B of the indicator rod 46 on the opposite side to the spring bearing 46A passes through a through-hole 40C formed in the housing 40 and protrudes to the outside of the housing 40 as the accumulator piston member 42 moves axially upward (see FIG. 4 ). Therefore, when hydraulic oil F is stored in the accumulator chamber 41, the tip 46B of the indicator rod 46 protrudes to the outside of the housing 40. This makes it possible to visually check whether the accumulator piston member 42 is moving normally based on the protruding state of the tip 46B, making it easier to discover any malfunctions in the accumulator device 4.

[0034] (Operation of Hydraulic Clamp Unit) Next, an example of operation of the hydraulic cylinder unit 1 will be described. Figures 2 to 6 are cross-sectional views showing an example of operation of the hydraulic cylinder unit 1. Specifically, Figure 2 shows an initial state in which the piston member 5 of the pressure oil supply / discharge device 2 is at the upper stroke end position. Figure 3 shows a state in which the piston member 5 has moved from the upper stroke end position shown in Figure 2 to the middle stroke position, and Figure 4 shows a state in which the piston member 5 has moved from the middle stroke position shown in Figure 3 to the lower stroke end position. Furthermore, Figure 5 shows a state in which the piston member 5 has moved from the lower stroke end position shown in Figure 4 to the middle stroke position, and Figure 6 shows a state in which the piston member 5 has moved from the middle stroke position shown in Figure 5 to the upper stroke end position.

[0035] 2 to 4, the pressure oil supply / discharge device 2 supplies hydraulic oil F to the cylinder device 3 when the piston member 5 moves from the initial state of the upper stroke end position to the lower stroke end position. Also, as shown in FIGS. 4 to 6, the pressure oil supply / discharge device 2 discharges hydraulic oil F from the cylinder device 3 when the piston member 5 moves from the lower stroke end position to the upper stroke end position.

[0036] As shown in Figure 2, when the piston member 5 of the pressure oil supply / discharge device 2 is at the upper stroke end position, the female screw member 6 is located above the male screw forming portion of the male screw member 7, and the piston member 5 is located directly below the cap member 8.

[0037] First, a recess formed at the tip of the torque transmission tool T for transmitting torque to the cap member 8 is fitted into the operating portion 81 of the cap member 8. Thereafter, when the torque transmission tool T is rotated in a first direction about its axis by operation by an operator or a robot, the cap member 8 fitted into the recess of the torque transmission tool T transmits the torque to the male screw member 7. When the male screw member 7 rotates due to the torque, the female screw member 6 that threads onto the male screw member 7 moves axially downward, and the piston member 5 provided on the female screw member 6 moves axially downward so as to move away from the cap member 8.

[0038] At this time, as shown in Figure 3, as the female screw member 6 that threads onto the male screw member 7 moves downward in the axial direction, a portion of the grease G (reference symbol G1 in the figure) that has been applied to the male screw member 7 is pushed downward by the female screw member 6 and moves. For this reason, as shown in Figure 4, when the piston member 5 moves to the vicinity of the lower end of the stroke, a grease pool G2 may form at the lower end of the male screw member 7.

[0039] As the piston member 5 moves downward in the axial direction, the pressure of the hydraulic oil F is increased in the working chamber 9, and the pressurized hydraulic oil F flows into the fluid passage 11 via the pressure accumulator 4 and is supplied to the working chamber 33 of the cylinder device 3 through the fluid passage 11. As the hydraulic oil F is supplied to the working chamber 33 of the cylinder device 3, a pressing force based on the hydraulic oil F supplied to the working chamber 33 acts to move the piston member 31 upward.

[0040] Next, with the piston member 31 of the cylinder device 3 moved to the upper stroke end position, the torque transmitting tool T further rotates the cap member 8 of the pressure oil supply / discharge device 2 in the first direction about its axis. This further increases the pressure of the hydraulic oil F. As a result, the hydraulic oil F in the working chamber 9 of the pressure oil supply / discharge device 2 is supplied to the accumulator chamber 41 of the pressure accumulator 4.

[0041] 4, a pressing force corresponding to the oil pressure of the hydraulic oil F supplied to the pressure accumulator chamber 41 moves the pressure accumulator piston member 42 axially upward against the biasing force of the compression spring 43. As the pressure accumulator piston member 42 moves axially upward, the tip end 46B of the indicator rod 46 projects outward from the housing 40. This makes it possible to visually confirm that the hydraulic oil F is being supplied to the pressure accumulator chamber 41 based on the projecting state of the tip end 46B.

[0042] For example, when a pressure drop of the hydraulic oil F in the fluid passage 11 occurs due to leakage of the hydraulic oil F or the like, the accumulator piston member 42 of the pressure accumulator device 4 compresses the accumulator chamber 41 due to the biasing force of the compression spring 43. Therefore, the hydraulic oil F stored in the accumulator chamber 41 is discharged to the fluid passage 11 in response to the pressure drop of the hydraulic oil F. This makes it possible to mitigate the pressure drop of the hydraulic oil F.

[0043] On the other hand, when the piston member 5 is at the stroke lower end position shown in Fig. 4 and the rotational force transmitting tool T rotates about its axis in a second direction opposite to the first direction, the piston member 5 moves axially upward so as to approach the cap member 8, as shown in Fig. 5 and Fig. 6. Then, the pressure of the hydraulic oil F decreases, and first, the hydraulic oil F stored in the accumulator chamber 41 of the accumulator 4 is discharged to the supply / discharge path 25 by the biasing force of the compression spring 43, and then the hydraulic oil F in the cylinder device 3 is discharged into the working chamber 9 of the pressure oil supply / discharge device 2 through the fluid passage 11.

[0044] At this time, as shown in Fig. 5, as the female screw member 6 that threads onto the male screw member 7 moves axially upward, a portion of the grease G applied to the male screw member 7 is pushed upward and moved by the female screw member 6 (reference symbol G3 in the figure). For this reason, as shown in Fig. 6, when the piston member 5 moves near the upper end of the stroke, a grease pool G4 may form on the outer peripheral surface near the upper end of the male screw member 7.

[0045] If grease pools G2 and G4 are formed, when the piston member 5 moves to the vicinity of the upper stroke end position, the grease pools G2 and G4 will resist the upward axial movement of the piston member 5, hindering smooth movement of the piston member 5. For this reason, a greater rotational force will be required to rotate the cap member 8 in the second direction, and a load will be applied to the rotational force transmission tool T that rotates the cap member 8 in the second direction.

[0046] As described above, the male thread member 7 is formed with an internal passage 70 for passing the grease G, which includes the first passage 71, the second passage 72, and the third passage 73. Therefore, the pressure oil supply / discharge device 2 is able to reduce the effects of the grease pools G2 and G4.

[0047] 6, when the piston member 5 reaches the upper stroke end position, a portion of the grease G forming the grease pool G2 at the lower end of the male thread member 7 flows from the first opening 71A into the first passage 71 (arrow A1 in the figure). Furthermore, a portion of the grease G forming the grease pool G2 on the outer peripheral surface near the upper end of the male thread member 7 flows from the second opening 72A into the second passage 72 (arrow A2 in the figure). This reduces the influence of the grease pools G2 and G4, allowing the piston member 5 to move smoothly.

[0048] Furthermore, the grease G that flows into the first passage 71 from the first opening 71A passes through the third passage 73 and is discharged from the third opening 73A. Similarly, the grease G that flows into the second passage 72 from the second opening 72A passes through the first passage 71 and the third passage 73 and is discharged from the third opening 73A (arrow A3 in the figure). Therefore, the grease G that flows into the internal passage 70 is discharged to the outer circumferential surface of the male thread member 7, allowing the grease G to be reused.

[0049] When the piston member 5 is at the upper end of its stroke, it is preferable that the second passage 72 opens at the upper end side relative to the female screw member 6, and the third passage 73 opens at the lower end side relative to the female screw member 6. In other words, when the piston member 5 is at the upper end of its stroke, it is preferable that the second opening 72A is located at the upper end side relative to the female screw member 6, and the third opening 73A is located at the lower end side relative to the female screw member 6. This allows the second passage 72 and the third passage 73 to be positioned so as to avoid the female screw member 6. In addition, the grease G that has flowed into the internal passage 70 can be discharged to the outer peripheral surface of the male screw member 7 from approximately the middle position in the axial direction of the male screw member 7.

[0050] Furthermore, it is preferable that the air pressure (internal pressure) within the internal space S of the housing 10 be adjusted so that it is equal to the external air pressure (1 atmosphere, atmospheric pressure) when the piston member 5 is at the midpoint of the piston stroke length. As the volume of the internal space S changes with the axial movement of the piston member 5, the air pressure within the airtight internal space S changes. For example, the air pressure within the internal space S is maximum when the piston member 5 is at the upper end of the stroke, and is minimum when the piston member 5 is at the lower end of the stroke.

[0051] Therefore, when the piston member 5 is at the intermediate position of the piston stroke length, that is, when the piston member 5 is at the intermediate position between the upper and lower stroke end positions as shown in Figures 3 and 5, the air pressure in the internal space S is adjusted to, for example, 1 atmosphere. This makes it possible to prevent the air pressure in the internal space S from becoming extremely high or low. This reduces the effect that changes in the air pressure in the internal space S have on the piston member 5, allowing the piston member 5 to move smoothly.

[0052] [Summary of the pressurized oil supply and discharge device] As described above, the pressurized oil supply and discharge device 2 according to this embodiment comprises: a bottomed, cylindrical piston member 5 that is inserted into the housing 10 so as to be axially movably and has a guide hole 53 therein; a female screw member 6 provided on the piston member 5; a male screw member 7 that is inserted into the guide hole 53 and screws into the female screw member 6 to move the piston member 5 in the axial direction, the male screw member 7 having an internal passage 70 through which grease G applied to the male screw member 7 passes; and a working chamber 9 to and from which hydraulic oil F is supplied and discharged as the piston member 5 moves.

[0053] In the pressure oil supply / discharge device 2, the piston member 5 provided on the female screw member 6 moves as the female screw member 6 moves along the axial direction of the male screw member 7. At this time, the grease G is pushed as the female screw member 6 moves in the axial direction, which may result in grease pools G2 and G4 forming on both end sides of the male screw member 7. In the pressure oil supply / discharge device 2, the male screw member 7 has an internal passage 70 through which grease passes, so the grease G can move inside the male screw member 7 through the internal passage 70. Therefore, according to this embodiment, the effects of the grease pools G2 and G4 can be reduced, and the movement of the piston member 5 can be made smoother.

[0054] Although the present embodiment has been described with reference to an example of a pressure oil supply / discharge device that supplies hydraulic pressure to a cylinder device, the present disclosure is not limited thereto. For example, the present disclosure can also be applied to an air supply / discharge device that supplies compressed air to a cylinder device instead of hydraulic pressure.

[0055] The present disclosure is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in the embodiments are also included in the technical scope of the present disclosure. Furthermore, new technical features can be formed by combining the technical means disclosed in the embodiments.

[0056] 1 to 6 , the present disclosure provides a fluid supply and discharge device configured as follows: A fluid supply and discharge device (pressurized oil supply and discharge device) 2 includes a bottomed, cylindrical piston member 5 that is inserted into a housing 10 so as to be axially movably and has a guide hole 53 therein, a female screw member 6 provided on the piston member 5, a male screw member 7 that is inserted into the guide hole 53 and threadably engages with the female screw member 6 to move the piston member 5 in the axial direction, the male screw member 7 having an internal passage 70 through which grease G applied to the male screw member 7 passes, and a working chamber 9 to and from which working fluid F is supplied and discharged as the piston member 5 moves.

[0057] One aspect of the present disclosure provides the following advantageous effects. When the female screw member moves along the axial direction of the male screw member, the piston member provided in the female screw member moves. At this time, the grease is pushed as the female screw member moves in the axial direction, and grease accumulation may occur, for example, on the end side of the male screw member. In the fluid supply / discharge device, the male screw member has an internal passage through which grease passes, allowing the grease to move inside the male screw member through the internal passage. Therefore, the effects of grease accumulation can be reduced, and the piston member can move smoothly.

[0058] The present disclosure preferably includes the following configurations (1) to (4).

[0059] (1) As shown in Figure 6, for example, the internal passage 70 includes a first passage 71 that passes through the axial center of the male thread member 7 and opens at the tip of the male thread member 7 located on the bottom 54 side of the piston member 5, a second passage 72 that branches off from the first passage 71 and opens on the outer circumferential surface of the base end of the male thread member located opposite the tip, and a third passage 73 that branches off from the first passage 71 and opens on the outer circumferential surface of the male thread member located on the tip side of the second passage 72. In this case, grease that accumulates on the tip end side of the male thread member can be made to flow into the first passage and discharged from the outer circumferential surface of the male thread member via the third passage for reuse. Also, grease that accumulates on the base end side of the male thread member can be made to flow into the second passage and discharged from the outer circumferential surface of the male thread member via the first and third passages for reuse.

[0060] (2) For example, as shown in Figures 2 and 6, when the piston member 5 is located at the stroke end on the base end side of the male screw member 7, the second passage 72 opens on the base end side relative to the female screw member 6, and the third passage 73 opens on the tip end side relative to the female screw member 6. In this case, the second passage and the third passage can be arranged to avoid the female screw member. Also, for example, grease that has flowed into the internal passage from the tip end side and base end side of the male screw member can be discharged from near the middle position in the axial direction of the male screw member to the outer circumferential surface of the male screw member.

[0061] (3) As shown in Figures 1 to 6, for example, the housing 10 is separated from the operating chamber 9 by the piston member 5 and has an internal space S in which the female screw member 6 and the male screw member 7 are disposed. The internal space S is airtight to prevent air from entering or leaving. In this case, no suction hole (breath hole) is provided for supplying or exhausting air from the internal space of the housing to the outside, so grease does not scatter (leak) to the outside through the breathing hole. This prevents a decrease in lubrication due to a decrease in grease and an increase in drive resistance. It also prevents damage to components in the internal space due to corrosion or wear caused by liquid, debris, etc. that has entered the internal space from the outside.

[0062] (4) For example, as shown in Figures 1, 3, and 5, the air pressure in the internal space S is adjusted to be equal to the external air pressure (1 atmosphere, atmospheric pressure) when the piston member 5 is at the midpoint of the piston stroke length. In this case, the air pressure in the airtight internal space can be prevented from becoming extremely high or low. Therefore, the effect of changes in air pressure in the internal space on the piston member can be reduced, and the movement of the piston member can be made smoother.

[0063] 2: Pressure oil supply / discharge device (fluid supply / discharge device) 5: Piston member 6: Female thread member 7: Male thread member 10: Housing 53: Guide hole 54: Bottom 70: Internal passage 71: First passage 72: Second passage 73: Third passage 71A: First opening 72A: Second opening 73A: Third opening F: Hydraulic oil (hydraulic fluid) G: Grease G1: Grease G2: Grease reservoir G3: Grease G4: Grease reservoir S: Internal space

Claims

1. A fluid supply and discharge device comprising: a cylindrical piston member with a bottom and an internal guide hole that is inserted into a housing so as to be axially movable; a female screw member provided on the piston member; a male screw member that is inserted into the guide hole and threadably engages with the female screw member to move the piston member in the axial direction, the male screw member having an internal passage through which grease applied to the male screw member passes; and a working chamber into which working fluid is supplied and discharged as the piston member moves.

2. A fluid supply / discharge device as described in claim 1, wherein the internal passage includes: a first passage that passes through the axial center of the male screw member and opens at the tip of the male screw member located on the bottom side of the piston member; a second passage that branches off from the first passage and opens at the outer peripheral surface of the base end side of the male screw member located opposite the tip; and a third passage that branches off from the first passage and opens at the outer peripheral surface on the tip side of the second passage.

3. A fluid supply / discharge device as described in claim 2, wherein, when the piston member is positioned at the stroke end on the base end side of the male screw member, the second passage opens on the base end side relative to the female screw member, and the third passage opens on the tip end side relative to the female screw member.

4. A fluid supply / discharge device as described in any one of claims 1 to 3, wherein the housing has an internal space separated from the operating chamber by the piston member and in which the female screw member and the male screw member are arranged, and the internal space is airtight to prevent air from entering or leaving.

5. A fluid supply / discharge device according to claim 4, wherein the air pressure in said internal space is adjusted to be equal to the external air pressure when said piston member is at an intermediate position of the piston stroke length of said piston member.

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