Cylinder device

Abstract

A cylinder device C according to the present invention is provided with: a telescopic unit 1 having a cylinder 2, a rod 3, a piston 4 for partitioning the inside of the cylinder 2 into a rod-side chamber 5 and a piston-side chamber 6, and a housing 7 for forming a reservoir tank 8 between the cylinder 2 and the piston 4; a pump unit (20) having a pump (22) capable of supplying liquid from the liquid storage tank (8) to the rod-side chamber (5); a variable pressure reducing valve (30) capable of imparting resistance to the flow of liquid flowing from the rod-side chamber (5) to the liquid storage tank (8); a first switching valve (40) provided between the rod-side chamber (5) and the piston-side chamber (6); and a second switching valve (41) provided between the piston-side chamber (6) and the reservoir tank (8). A part of a passage connecting the rod-side chamber (5) and the first switching valve (40) or a part of a passage connecting the piston-side chamber (6) and the first switching valve (40) is formed by an outer duct (50) disposed outside the housing (7).

Description

[TECHNICAL FIELD]

[0001] The present application relates to a cylinder device. [BACKGROUND]

[0002] Conventionally, such a cylinder device is used on a vibration object, with the aim of suppressing vibration generated by the vibration object. For example, in order to suppress vibration in the left-right direction with respect to the direction of travel of a vehicle body in a railway vehicle, a cylinder device that is inserted between the vehicle body and a bogie is known.

[0003] This cylinder device is used by being sandwiched between the bogie of a railway vehicle and a kingpin provided at the lower portion of the vehicle body of the railway vehicle, and is able to suppress vibration of the vehicle body in the lateral direction with respect to the direction of travel of the railway vehicle using the output damping force or thrust force, and improve the ride comfort of the railway vehicle.

[0004] A cylinder device, as shown in Japanese Patent JP7352710B, has a telescopic unit having a cylinder, a housing that covers the cylinder and forms a liquid reservoir between the cylinder, a rod member that is inserted into the cylinder so as to be movable in the axial direction, a piston that is freely slidably inserted into the cylinder and is coupled to the rod member and divides the inside of the cylinder into a rod member side chamber and a piston side chamber, a pump unit that is provided in the middle of a supply passage that communicates the rod member side chamber and the liquid reservoir and has a pump that is able to supply liquid from the liquid reservoir to the rod member side chamber and a motor that drives the pump, a variable pressure reducing valve that is provided in the middle of a discharge passage that communicates the rod member side chamber and the liquid reservoir, a first on-off valve that is provided in the middle of a first passage that communicates the rod member side chamber and the piston side chamber, and a second on-off valve that is provided in the middle of a second passage that communicates the piston side chamber and the liquid reservoir. The cylinder device suppresses vibration of the vehicle body by the drive of the pump to exert thrust force. [SUMMARY]

[0005] [PROBLEMS TO BE SOLVED BY THE INVENTION]

[0006] In some railway vehicles that utilize a cylinder device, i.e. a vibration object, it is possible that they are incorporated into a marshalling train in which trains with different destinations are coupled to each other. When such a marshalling train enters a tunnel, the phenomenon of airflow turbulence occurs at the coupled portion in the marshalling train and the vehicle body vibrates at high speed, but if the vehicle body vibrates at high speed and the telescopic unit telescopes, the flow rate of the pump cannot follow the volume change in the cylinder, which can result in the cylinder device being unable to control the vibration of the vehicle body.

[0007] To increase the flow rate of the pump, it is only necessary to make the pump large, but if the pump is simply made large and the motor is able to output a small torque, the discharge pressure of the pump decreases and the thrust exerted by the cylinder device becomes small, so the motor is also made large while the pump is made large. Thus, if the cylinder device is used in a case where it is possible to be extended and contracted at high speed by an external force, it is necessary to make the pump unit large.

[0008] If the pump unit is made large, the size of the entire cylinder device increases, which results in a decrease in the mounting performance on the vibration-damping object, so it is possible to reduce the diameter of the housing as much as possible to avoid the large size of the cylinder device.

[0009] On the other hand, in the conventional cylinder device, since it is necessary to communicate the rod-side chamber with the piston-side chamber, a pipeline that forms a passage in communication with the rod-side chamber and isolated from the liquid reservoir between the cylinder and the housing is housed in the liquid reservoir, and the first on-off valve is communicated with the rod-side chamber using the passage as a part of the first passage. The conventional cylinder device needs to house the pipeline in the liquid reservoir, and also needs to ensure the passage area in the pipeline, so even if the volume of the cylinder device is reduced by shortening the outer diameter of the housing, it is not possible to achieve miniaturization.

[0010] Therefore, the conventional cylinder device has a problem in that if the size of the pump unit is increased so that the thrust can be exerted even at high speed, the mounting performance on the vibration-damping object decreases.

[0011] Therefore, the conventional cylinder device has a problem in that if the size of the pump unit is increased so that the thrust can be exerted even at high speed, the mounting performance on the vibration-damping object decreases.

[0012] [Means for solving the problem]

[0013] To achieve the object, the cylinder device of the present application has: an extension unit having a cylinder, a rod member that is inserted into the cylinder so as to be movable in the axial direction, a piston that is inserted into the cylinder so as to be movable in the axial direction and is connected to the rod member and that divides the inside of the cylinder into a rod-side chamber and a piston-side chamber, and a housing that is cylindrical and is disposed on the outer periphery of the cylinder and that forms a liquid reservoir for storing a liquid between the cylinder; a pump unit that is provided between the rod-side chamber and the liquid reservoir and that has a pump that is capable of supplying the liquid from the liquid reservoir toward the rod-side chamber and a motor that is used to drive the pump; a variable pressure-reducing valve that is provided between the rod-side chamber and the liquid reservoir and that is used to apply resistance to the flow of the liquid flowing from the rod-side chamber toward the liquid reservoir; a first on-off valve that is provided between the rod-side chamber and the piston-side chamber; and a second on-off valve that is provided between the piston-side chamber and the liquid reservoir. A part of the passage that connects the rod-side chamber and the first on-off valve or a part of the passage that connects the piston-side chamber and the first on-off valve is formed by an external pipeline that is disposed on the outside of the housing.

[0014] In this type of cylinder device, in order to switch the connection and disconnection between the rod-side chamber and the piston-side chamber via the first switching valve, it is necessary to connect the rod-side chamber and the piston-side chamber. However, since the passage connecting the rod-side chamber and the first switching valve, or part of the passage connecting the piston-side chamber and the first switching valve, is formed by an external pipe located outside the housing, in order to ensure the thrust during high-speed extension and retraction, even if the pump capacity is increased and the size of the motor is also increased, it is no longer necessary to install a pipeline covering the entire axial length of the reservoir inside the housing to connect the rod-side chamber and the piston-side chamber. The outer diameter of the housing can be reduced, thereby reducing the size of the cylinder device. [Image Description]

[0015] Figure 1 This is a side view of a cylinder assembly in one embodiment.

[0016] Figure 2 This is a partially enlarged side view of the cylinder assembly in one embodiment.

[0017] Figure 3 This is a cross-sectional view of the pump section of the cylinder assembly in one embodiment.

[0018] Figure 4 This is a cross-sectional view of the ring portion of the cylinder assembly in one embodiment.

[0019] Figure 5 This is a partially enlarged longitudinal cross-sectional view of the cylinder assembly in a variation of one implementation method. [Detailed Implementation]

[0020] The present invention will now be described with reference to the embodiments shown in the figures. In one embodiment, the cylinder device C, as... Figure 1 and Figure 2 As shown, the device comprises a telescopic unit 1, a pump unit 20, a variable pressure reducing valve 30, a first switching valve 40, a second switching valve 41, and an external pipe 50. Although not shown in detail, the cylinder device C of this embodiment is designed to dampen vibrations in railway vehicles. It is mounted between the railway vehicle body and the trolley, and suppresses horizontal lateral vibrations of the vehicle body relative to the vehicle's direction of travel through the damping force generated during telescopic movement. Furthermore, the cylinder device C can also be used for damping vibrations in non-railway vehicles, such as non-railway vehicles or machinery.

[0021] The following is a detailed explanation of each part. For example... Figure 1 and Figure 2As shown, the telescopic unit 1 is provided with a cylinder 2, a rod member 3 which is inserted into the cylinder 2 so as to be movable in the axial direction, a piston 4 which is inserted into the cylinder 2 so as to be movable in the axial direction and is connected to the rod member 3, and separates the inside of the cylinder 2 into a rod member side chamber 5 and a piston side chamber 6, a housing 7 which is cylindrical and is arranged on the outer periphery of the cylinder 2 and forms a liquid storage tank 8 for storing liquid between the cylinder 2, and an intermediate cylinder 9 which covers the left end to the vicinity of the center of the cylinder 2.

[0022] The cylinder 2 is cylindrical, Figure 2 The inner periphery of the left end is fitted with a ring-shaped guide 10, and Figure 2 The inner periphery of the right end is fitted with a valve housing 11. The left end of the cylinder 2 is closed by the guide 10, and the right end of the cylinder 2 is closed by the valve housing 11. Further, the outer periphery of the intermediate portion of the cylinder 2 is formed with an enlarged diameter portion 2a which has a larger outer diameter than the other portions. Further, the cylinder 2 is provided with a through-hole 2b which penetrates the wall thickness in the vicinity of the left end. Figure 2

[0023] Further, the rod member 3 which is freely inserted into the cylinder 2 is freely slidably inserted into the guide 10. One end of this rod member 3 projects out of the cylinder 2, and the other end in the cylinder 2 is connected to the piston 4 which is freely slidably inserted into the cylinder 2. Further, a bracket 3a is provided at the other end of the rod member 3, and the bracket can be mounted on a mounting portion provided on a bogie of a railway vehicle.

[0024] Further, the inside of the cylinder 2 is divided by the piston 4 into the rod member side chamber 5 for passing through the rod member 3 and the piston side chamber 6 which does not pass through the rod member 3. These rod member side chamber 5 and piston side chamber 6 are filled with liquid such as hydraulic oil. The piston 4 is provided with a flow regulating passage 14 which allows the liquid to flow from the piston side chamber 6 to the rod member side chamber 5 but prevents the liquid from flowing from the rod member side chamber 5 to the piston side chamber 6.

[0025] The flow regulating passage 14 communicates the piston side chamber 6 and the rod member side chamber 5, has a check valve 14a in the middle, and is set as a one-way passage which allows the hydraulic oil to flow only from the piston side chamber 6 to the rod member side chamber 5.

[0026] Next, the outer periphery of the cylinder 2 is provided with the cylindrical housing 7 which covers the outer periphery of the cylinder 2. The inner periphery of the left end of the housing 7 is fitted with the guide 10, and the left end of the housing 7 is closed by the guide 10. Further, the left end of the housing 7 is mounted with the ring-shaped seal housing 12 which is fitted in the left side of the guide 10. Figure 2 Figure 2 Further, the left end of the housing 7 is mounted with the ring-shaped seal housing 12 which is fitted in the left side of the guide 10. Figure 2 Further, the left end of the housing 7 is mounted with the ring-shaped seal housing 12 which is fitted in the left side of the guide 10.

[0027] The outer periphery of the housing 7​​Figure 2 The right end of the outer shell 7 is closed by a bottom cover 13. The bottom cover 13 is joined to the right end of the outer shell 7 by welding or the like, and has a bracket 13a at the right end, which can be fitted to an unillustrated mounting portion provided on a vehicle body of a railway vehicle. Thus, by means of the bracket 3a of the rod member 3 and the bracket 13a of the bottom cover 13, the telescopic unit 1 of the cylinder device C can be fitted between the unillustrated vehicle body and a bogie.

[0028] Furthermore, if the bottom cover 13 is fitted to the right end of the outer shell 7 and the seal housing 12 is fitted to the left end of the outer shell 7, the guide member 10, the cylinder 2, and the valve housing 11 housed in the outer shell 7 are sandwiched between the bottom cover 13 and the seal housing 12 and fixed in the outer shell 7.

[0029] Thus, an annular liquid reservoir 8 storing a liquid is formed between the outer shell 7 and the cylinder 2 housed inside the outer shell 7. Specifically, the same liquid as that filled in the cylinder 2 is filled in the liquid reservoir 8, and also a gas is filled, and the pressure of the liquid reservoir 8 is substantially atmospheric pressure.

[0030] The valve housing 11 fitted to the end portion of the cylinder 2 has a cylindrical fitting shaft 11a extending in the axial direction from the right end in Figure 2 and has a vertical hole 11b opening at the right end of the fitting shaft 11a to communicate with the piston-side chamber 6, and a suction passage 19 allowing only the liquid to flow from the liquid reservoir 8 to the piston-side chamber 6. The suction passage 19 communicates the liquid reservoir 8 and the piston-side chamber 6 while avoiding the portion of the fitting shaft 11a of the valve housing 11 in the axial direction, and has a check valve 19a thereon, which is set as a one-way passage allowing only the hydraulic oil to flow from the liquid reservoir 8 to the piston-side chamber 6.

[0031] The bottom cover 13 has a recess 13b in which the inner diameter is reduced in the middle, a cutout groove 13c formed at the left end in Figure 2 to communicate the large-diameter portion of the recess 13b with the liquid reservoir 8, a piston-side chamber communication passage 13d opening at the front end of the recess 13b to communicate with Figure 2 the lower end in Figure 2 the lower end in

[0032] The small diameter portion of the recess 13b of the bottom cover 13, which is reduced in diameter, is fitted with the fitting shaft 11a of the valve housing 11, and the bottom cover 13 is fitted into the recess 13b by the fitting shaft 11a to position the valve housing 11 in the radial direction with respect to the case 7. Since the piston-side chamber communication passage 13d opens at the front end of the recess 13b, it communicates with the piston-side chamber 6 through the vertical hole 11b of the valve housing 11. Further, one end of the suction passage 19 provided on the valve housing 11 communicates with the recess 13b of the bottom cover 13, and communicates with the reservoir 8 through the recess 13b and the cutout groove 13c. Further, one end of the reservoir communication passage 13e communicates with the reservoir 8 through the cutout groove 13c facing the reservoir 8.

[0033] Next, the case 7 is provided with a hole 7a penetrating the wall thickness on the left upper side in Figure 2 , and a hole 7b penetrating the wall thickness on the lower side near the center in Figure 1 . Further, a valve seat 15 for mounting the variable pressure reducing valve 30 to the case 7 is mounted on the position of the annular surrounding hole 7a on the outer periphery of the case 7, and similarly, a seat 16 for mounting the pump unit 20 to the case 7 is mounted on the position of the annular surrounding hole 7b on the outer periphery of the case 7.

[0034] The valve seat 15 is rectangular when viewed in the radial direction of the case 7, has a curved surface along the outer periphery of the case 7 on the end portion toward the case 7 side, and has a flat surface for easy mounting of the variable pressure reducing valve 30 on the end portion toward the side opposite to the case, as shown in Figure 2 , and has a hole 15a communicating with the hole 7a in the center. When the valve seat 15 is mounted to the outer periphery of the case 7 with the curved surface facing the case 7, the hole 15a communicates with the inside of the reservoir 8 with the hole 7a directly opposite.

[0035] As shown in Figure 3 , Figure 3 and Figure 3 , the seat 16 has a base portion 16a which is circular plate-shaped when viewed in the radial direction of the case 7 and has a curved surface along the outer periphery of the case 7 on the side facing the case 7, a support portion 16b connected to the side opposite to the case of the base portion 16a and having a flat mounting surface 16c for mounting the pump unit 20 to the side opposite to the case, a through hole 16d opening in the mounting surface 16c and penetrating the support portion 16b and the base portion 16a, which, if fixed to the outer periphery of the case 7, has the through hole 16d directly opposite to the hole 7b, and which communicates with the inside of the reservoir 8. Further, the rod member 3 is omitted in Figure 3 .

[0036] The base portion 16a is cylindrical, and has a curved surface 16a1 along the outer periphery of the case 7 on the end portion on the case 7 side. Although the center of curvature of the curved surface 16a1 coincides with the center of the outer periphery of the case 7, as shown in Figure 3As shown, the axis Z passing through the center of the circular base 16a is offset to the left from the axis Y of the outer casing 7. Therefore, the axial length of the base 16a is... Figure 2 Compared to the middle left side Figure 3 The right side is longer.

[0037] Support part 16b in Figure 3 When viewed from below the outer shell 7, it appears rectangular, as shown below. Figure 3 As shown, the center extends from the center of the disk-shaped base 16a towards... Figure 3 It is eccentric on the left side and connected to the base 16a. The support part 16b... Figure 3 The middle right end and the base 16a Figure 3 The right end of the middle part is roughly coplanar, but due to the support part 16b Figure 3 The length of the support portion 16b in the left-right direction is longer than the diameter of the base 16a; therefore, the support portion 16b extends from the base 16a... Figure 3 The support portion 16b protrudes to the left. Thus, the support portion 16b relative to the base 16a... Figure 3 The connection is offset to the left, so if the base 16 is mounted on the housing 7, the line X perpendicular to the mounting surface 16c of the support 16b and passing through the center of the mounting surface 16c and the axis Y of the housing 7 are in a torsional position that do not intersect each other. The mounting surface 16c is positioned on... Figure 3 It is located at a position offset to the left relative to the outer shell 7.

[0038] Furthermore, the axis of the through hole 16d is aligned with line X, orthogonal to the mounting surface 16c, and passes through the center of the mounting surface 16c, and is positioned on the base 16. Figure 2 In the middle, it is positioned offset to the left from the center of the base 16a relative to the base 16a. The axis Z passing through the center of the circular base 16a is in... Figure 2 The wall thickness of the base 16 is offset to the left from the axis Y of the outer casing 7, and the left side of the wall thickness along the axis Z of the base 16a is thicker than the right side. The through hole 16d is offset from the center of the base 16a to the left side where the wall thickness is thicker, so the reduction in strength of the base 16 due to the setting of the through hole 16d can be mitigated.

[0039] Next, the guide 10 is ring-shaped and is inserted into the housing 7. Figure 2 The inner circumference of the left end and Figure 2 The right end has a protrusion 10a that protrudes to the right. The front end side of the protrusion 10a, i.e. Figure 2 The outer diameter of the right end is reduced, and it has a small diameter portion 10a1 on the front end side and a large diameter portion 10a2 on the base end side. The guide 10 fits the small diameter portion 10a1 into the cylinder 2. Figure 2 The inner circumference of the middle left end is clamped to the housing 7. Figure 2 The sealing housing 12 on the left side is between and fixed inside the outer casing 7 and the cylinder 2.

[0040] Further, the guide 10 has a seal ring 10b in sliding contact with the outer periphery of the rod member 3 and a cylindrical boss 10c on the inner periphery. The seal ring 10b prevents liquid from leaking from the inside of the extension unit 1. Since the rod member 3 is guided to move in the axial direction by the boss 10c, the rod member 3 can smoothly move in the axial direction without axial shake with respect to the cylinder 2.

[0041] Further, the outer periphery of the large-diameter portion 10a2 of the guide 10 is fitted with the intermediate cylinder 9 Figure 2 at the left end thereof, which covers the position from the right end to the intermediate portion of the cylinder 2 Figure 2 . The right end of the intermediate cylinder 9 is fitted to the outer periphery of the enlarged diameter portion 2a of the cylinder 2. Figure 2

[0042] Further, the enlarged diameter portion 2a of the cylinder 2 has a flange 2a1 opposite to the right end of the intermediate cylinder 9. When the intermediate cylinder 9 is fitted to the large-diameter portion 10a2 and the enlarged diameter portion 2a of the guide 10, the movement of the intermediate cylinder 9 in the left-right direction with respect to the axial direction of the cylinder 2, i.e., the direction of the arrow A, is restricted by the flange 2a1 and the guide 10. Figure 2 Figure 2

[0043] The intermediate cylinder 9 has a hole 9a penetrating the wall thickness in the radial direction at the left upper side, a hole 9b penetrating the wall thickness in the radial direction at the right lower side, a ring-shaped sleeve 9c protruding in the radial direction from the outer periphery and surrounding the hole 9a, and a ring-shaped sleeve 9d protruding in the radial direction from the outer periphery and surrounding the hole 9b. Figure 2 Figure 2 Further, the right end of the intermediate cylinder 9 is fitted to the outer periphery of the enlarged diameter portion 2a of the cylinder 2, and a ring-shaped passage P1 is formed between the intermediate cylinder 9 and the cylinder 2. Further, the left end of the ring-shaped passage P1 is closed due to the fitting of the guide 10 to the left end of the intermediate cylinder 9, and the right end thereof is closed due to the fitting of the enlarged diameter portion 2a to the right end of the intermediate cylinder 9, which communicates with the inside of the rod member side chamber 5 through the through hole 2b provided on the cylinder 2, but does not communicate with the inside of the liquid reservoir 8. In this way, the ring-shaped passage P1 is formed by the intermediate cylinder 9 covering the cylinder 2 and a part of the outer periphery of the cylinder 2.

[0044] Further, the right end of the intermediate cylinder 9 is fitted to the outer periphery of the enlarged diameter portion 2a of the cylinder 2, and a ring-shaped passage P1 is formed between the intermediate cylinder 9 and the cylinder 2. Further, the left end of the ring-shaped passage P1 is closed due to the fitting of the guide 10 to the left end of the intermediate cylinder 9, and the right end thereof is closed due to the fitting of the enlarged diameter portion 2a to the right end of the intermediate cylinder 9, which communicates with the inside of the rod member side chamber 5 through the through hole 2b provided on the cylinder 2, but does not communicate with the inside of the liquid reservoir 8. In this way, the ring-shaped passage P1 is formed by the intermediate cylinder 9 covering the cylinder 2 and a part of the outer periphery of the cylinder 2. Figure 2 Figure 1 Figure 2

[0045] As shown in Figs. 1 and 2, the extension unit 1 has a cylinder 2, a rod member 3, a guide 10, a liquid reservoir 8, and a liquid supply mechanism 4. Figure 2 Figure 2 ​​​​​​​​As shown, the pump unit 20 is provided with: a pump housing 21 provided with a pump 22 and mounted on the mounting surface 16c of the base 16; and a motor 23 held on the pump housing 21. The pump 22 is a one-way jet type pump that sucks liquid from the liquid reservoir 8 and supplies the liquid to the rod-side chamber 5, and can be, for example, a gear pump. In addition, the pump 22 can also be a two-way jet type pump or a piston pump, etc.

[0046] The pump housing 21 is provided with: a main body 21a that is a rectangular parallelepiped having a flat mounting surface 21b opposite the mounting surface 16c and fixed to the base 16; a pump accommodating portion 21c that protrudes to the right from the right end of the main body 21a, i.e., the side opposite the rod, and internally accommodates the pump 22; a blind hole 21d that opens near the center of the mounting surface 21b; a suction passage 21e that opens from the portion of the mounting surface 21b opposite the through-hole 16d of the base 16 and communicates with the suction port of the pump 22; a supply passage 21f that communicates the discharge port of the pump 22 and the blind hole 21d; a pipe insertion hole 21g that opens on the side of the main body 21a closer to the housing 7, i.e., the upper side, than the pump accommodating portion 21c; and a branch passage 21h that communicates the supply passage 21f and the pipe insertion hole 21g. Figure 2 Figure 2 The pump accommodating portion 21c protrudes to the right from the right end of the main body 21a, i.e., the side opposite the rod, and internally accommodates the pump 22. The blind hole 21d opens near the center of the mounting surface 21b. The suction passage 21e opens from the portion of the mounting surface 21b opposite the through-hole 16d of the base 16 and communicates with the suction port of the pump 22. The supply passage 21f communicates the discharge port of the pump 22 and the blind hole 21d. The pipe insertion hole 21g opens on the side of the main body 21a closer to the housing 7, i.e., the upper side, than the pump accommodating portion 21c. The branch passage 21h communicates the supply passage 21f and the pipe insertion hole 21g.

[0047] The motor 23 is provided with a rotor 23a and is mounted on the left side of the middle side portion of the main body 21a of the pump housing 21. The rotor 23a is linked to the non-illustrated drive shaft of the pump 22. Figure 2

[0048] Furthermore, since the blind hole 21d and the sleeve 9d of the intermediate cylinder 9 are directly opposite, the pump housing 21 and the intermediate cylinder 9 are provided with a cylindrical connection pipe 17 that makes the supply passage 21f and the annular passage P1 inside the intermediate cylinder 9 communicate. One end of the connection pipe 17 is fitted inside the blind hole 21d, and the other end is fitted inside the sleeve 9d, and is fixed to the pump housing 21 and the intermediate cylinder 9.

[0049] Therefore, the supply passage 21f connected to the discharge port of the pump 22 communicates with the rod-side chamber 5 through the connection pipe 17 and the annular passage P1. On the other hand, the suction passage 21e connected to the suction port of the pump 22 communicates with the liquid reservoir 8. When the motor 23 is driven, the pump 22 can suck liquid from inside the liquid reservoir 8 through the suction passage 21e and supply the liquid to inside the rod-side chamber 5 through the supply passage 21f.

[0050] ​​Next, the variable pressure reducing valve 30 is provided on a valve block 31 mounted on the valve base 15, and constitutes a pressure reducing valve unit together with the valve block 31. The valve block 31 has a valve housing 31a mounted on the valve base 15 in a state of abutting against the flat surface of the valve base 15, a cylindrical protrusion 31b protruding from the lower side of the valve housing 31a and fitted in the hole 15a of the valve base 15, two blind holes 31c, 31d opened from the lower side of the cylindrical protrusion 31b and facing each other in the upper side, an inner block passage 31e opened from the bottom of the blind hole 31c and communicating with the bottom of the blind hole 31d. Figure 2 Figure 4 The two blind holes 31c, 31d opened from the lower side of the cylindrical protrusion 31b and facing each other in the upper side, the inner block passage 31e opened from the bottom of the blind hole 31c and communicating with the bottom of the blind hole 31d.

[0051] If the valve block 31 is mounted on the valve base 15, the blind hole 31c facing the liquid tank 8 side is opposed to the sleeve 9c of the intermediate cylinder 9 in the radial direction of the housing 7 through the hole 7a. One end of the inner block passage 31e opened from the bottom of the blind hole 31c communicates with the hole 9a surrounded by the sleeve 9c of the intermediate cylinder 9 through the connection pipe 18. One end of the connection pipe 18 is fitted in the blind hole 31c, and the other end is fitted in the sleeve 9c, and is fixed to the valve block 31 and the intermediate cylinder 9.

[0052] Further, one end of the cylindrical discharge pipe 32 is fitted in the blind hole 31d facing the liquid tank 8 side through the hole 7a. The discharge pipe 32 is mounted on the valve block 31, extends in the radial direction of the housing 7, and protrudes into the liquid tank 8. The other end of the discharge pipe 32 is fitted in the ring 33 mounted on the outer periphery of the intermediate cylinder 9 as shown in Figs. 4 and 5. Figure 2 Figure 2 The ring 33 is annular, is fitted in the outer periphery of the intermediate cylinder 9, and has an annular groove 33a formed in the inner periphery and formed in the circumferential direction, a through hole 33b provided at a position opposed to the blind hole 31d of the valve block 31 in the radial direction of the housing 7, opened from the bottom of the annular groove 33a and radially penetrating the wall thickness, and a discharge hole 33c penetrating the wall thickness from the outer periphery of the lowermost portion and communicating with the annular groove 33a. Figure 2

[0053] If the ring 33 is fitted in the outer periphery of the intermediate cylinder 9, the sealing rings 33d, 33e mounted on both sides of the annular groove 33a in the inner periphery of the ring 33 and in the axial direction are in close contact with the outer periphery of the intermediate cylinder 9. Therefore, when the ring 33 is fitted in the outer periphery of the intermediate cylinder 9, the annular groove 33a and the discharge hole 33c form the liquid tank inner passage P2.

[0054] Further, the discharge pipe 32 is fitted in the through hole 33b of the ring 33, and the other end of the inner block passage 31e communicates with the annular groove 33a of the ring 33 through the inside of the discharge pipe 32. The inside of the discharge pipe 32 communicates with the other end of the inner block passage 31e through the liquid tank inner passage P2, and communicates with the liquid tank 8 through the hole 7a. Figure 4 ​​​In addition to being connected to the lower part of the middle section, it is also connected to the internal channel 31e of the valve block 31. Therefore, the internal channel 31e is connected to the lower part of the storage tank 8 through the discharge pipe 32 and the internal channel P2 of the storage tank.

[0055] The variable pressure reducing valve 30 is disposed in the intra-block passage 31e within the valve block 31. It includes a valve body 30a for opening or closing the intra-block passage 31e, a spring 30b applying a force to the valve body 30a in the direction of closing the intra-block passage 31e, a pilot passage 30c applying pressure to the valve body 30a in the direction of opening the intra-block passage 31e, and a solenoid 30d mounted on the valve block 31 for driving the valve body 30a. One end of the intra-block passage 31e is connected to the rod-side chamber 5 via a connecting pipe 18 and an annular passage P1, while the other end is connected to the interior of the storage tank 8 via a discharge pipe 32 and a storage tank passage P2. Therefore, the intra-block passage 31e, connecting pipe 18, annular passage P1, through hole 2b, discharge pipe 32, and storage tank passage P2 form a discharge passage EP, and the variable pressure reducing valve 30 is disposed in the discharge passage EP.

[0056] The pilot passage 30c of the variable pressure reducing valve 30 causes the pressure in the stem-side chamber 5 to act on the valve body 30a in the opening direction. The solenoid 30d is mounted on the valve block 31. Figure 4 Although not shown in detail, the right end of the device includes a plunger 30d1, a coil for driving the plunger 30d1, a fixed iron core that attracts the plunger 30d1 when the coil is energized, and a frame 30d2 for housing the coil and the fixed iron core. Furthermore, when energized, the solenoid 30d drives the plunger 30d1 in a direction protruding from the frame 30d2, applying a thrust to the valve body 30a of the variable pressure reducing valve 30 to resist the force of the spring 30b and press the valve body 30a towards the opening direction. In addition, the solenoid 30d can adjust the magnitude of the thrust according to the applied current, and when not energized, it does not apply a thrust to the valve body 30a.

[0057] Thus, since the solenoid 30d can adjust the magnitude of the thrust applied to the valve body 30a according to the current supplied, the opening pressure of the variable pressure reducing valve 30 can be adjusted. In this embodiment, if the current supplied to the solenoid 30d is set to the maximum, the opening pressure of the variable pressure reducing valve 30 is set to the minimum; if no current is supplied to the solenoid 30d, the opening pressure is set to the maximum. Furthermore, when the variable pressure reducing valve 30 is open, liquid is allowed to move from the rod-side chamber 5 to the reservoir 8 through the discharge channel EP, and the opening pressure of the variable pressure reducing valve 30 can be adjusted according to the current supplied to the solenoid 30d. Therefore, the variable pressure reducing valve 30 can control the pressure in the upstream rod-side chamber 5 connected through the discharge channel EP by the current supplied to the solenoid 30d.

[0058] Further, the liquid passing through the variable pressure reducing valve 30 is discharged from the discharge hole 33c to the lower side of the reservoir tank 8 through the discharge line 32 and the reservoir tank passage P2. Therefore, even if the variable pressure reducing valve 30 is arranged above the housing 7 when the cylinder device C is used horizontally, the liquid passing through the variable pressure reducing valve 30 can be discharged to the lower side of the liquid surface in the reservoir tank 8. Therefore, even if the variable pressure reducing valve 30 is arranged above the housing 7, the liquid passing through the variable pressure reducing valve 30 can be discharged to the upper side of the liquid surface in the reservoir tank 8, so that the gas entrainment in the liquid in the reservoir tank 8 can be prevented. Further, since the arrangement position of the through hole 33b and the discharge hole 33c of the ring 33 can be arbitrarily changed with respect to the ring 33 depending on the arrangement position of the variable pressure reducing valve 30 with respect to the housing 7, by forming the reservoir tank passage P2 by the ring 33, the discharge hole 33c can be easily arranged to the lower side of the liquid surface in the reservoir tank 8 in correspondence with the arrangement position of the variable pressure reducing valve 30. Further, if the opening position of the discharge hole 33c of the ring 33 in the reservoir tank 8 is below the lower side of the reservoir tank 8, the gas entrainment prevention effect is better, but as shown in Figure 2 , if the liquid surface S of at least the liquid O in the reservoir tank 8 is below the lower side of the reservoir tank 8, the liquid passing through the variable pressure reducing valve 30 can be discharged to the lower side of the liquid surface S, so that the liquid in the reservoir tank 8 can be prevented from being entrained into the gas. Further, in Figure 2 , the rod member 3 is omitted.

[0059] The first and second on-off valves 40 and 41 are arranged on the valve block 42 mounted on the lower side of the bottom cover 13, i.e., the side surface, and constitute an on-off valve unit together with the valve block 42. The valve block 42 is attached to the side of the bottom cover 13, and has a line insertion hole 42a which is opened at the left end in the axial direction of the housing 7, i.e., the end facing the pump unit 20, and a first passage 42b which is opened at the bottom of the line insertion hole 42a and communicates with the upper end in the axial direction of the housing 7. Figure 2 Figure 2 Figure 2 Figure 2

[0060] ​​​​The first switch valve 40 is provided at a position on the first passage 42b that is closer to the line insertion hole 42a than the connection point with the second passage 42c. The first switch valve 40 has a valve body 40a that has a communication position that opens the first passage 42b and a cutoff position that cuts off the first passage 42b, a spring 40b that applies a force to the valve body 40a to move it to the cutoff position, and a solenoid 40c that can apply a pushing force to the valve body 40a to move it to the communication position against the force of the spring 40b. In a state in which the solenoid 40c is not energized, the valve body 40a is in the cutoff position to cut off the first passage 42b, and if the solenoid 40c is energized, the valve body 40a is in the communication position to open the first passage 42b.

[0061] On the other hand, the second switch valve 41 is provided on the second passage 42c. The second switch valve 41 has a valve body 41a that has a communication position that opens the second passage 42c and a cutoff position that cuts off the second passage 42c, a spring 41b that applies a force to the valve body 41a to move it to the cutoff position, and a solenoid 41c that can apply a pushing force to the valve body 41a to move it to the communication position against the force of the spring 41b. In a state in which the solenoid 41c is not energized, the valve body 41a is in the cutoff position to cut off the second passage 42c, and if the solenoid 41c is energized, the valve body 41a is in the communication position to open the second passage 42c.

[0062] If the valve block 42 of the switch valve unit thus configured is attached to the bottom cover 13, the first passage 42b is connected to the piston-side chamber communication passage 13d of the bottom cover 13, and the second passage 42c is connected to the reservoir communication passage 13e. In addition, if the valve block 42 of the switch valve unit is attached to the bottom cover 13, the line insertion hole 42a of the valve block 42 and the line insertion hole 21g of the pump seat 21 are opposed in the axial direction of the housing 7. Thus, the external pipe 50 that communicates the first passage 42b and the branch passage 21h is provided on the outside of the housing 7 and is attached and fixed to the valve block 42 of the switch valve unit and the pump seat 21 of the pump unit 20.

[0063] The external pipe 50 is formed of a metal pipe, and by fitting one end of the pipe into the line insertion hole 42a and the other end into the line insertion hole 21g, it can be arranged on the outside of the housing 7 and attached and fixed to the valve block 42 of the switch valve unit and the pump seat 21 of the pump unit 20. In addition, the external pipe 50 can be formed of a flexible pressure-resistant hose in addition to a pipe.

[0064] A first channel 42b, equipped with a first switching valve 40, is connected at one end to the rod-side chamber 5 via an external pipe 50, a branch channel 21h and a supply channel 21f of the pump seat 21, a connecting pipe 17, an annular channel P1, and a through hole 2b. The other end is connected to the piston-side chamber 6 via a piston-side chamber connecting channel 13d and a vertical hole 11b. Therefore, if the first switching valve 40 is opened, the rod-side chamber 5 and the piston-side chamber 6 are connected via the first channel 42b. If the first switching valve 40 is closed, the first channel 42b is cut off, and the connection between the rod-side chamber 5 and the piston-side chamber 6 via the first channel 42b is also cut off.

[0065] Additionally, a second channel 42c, equipped with a second switching valve 41, is connected at one end to the piston-side chamber 6 via a first channel 42b, a piston-side chamber connecting channel 13d, and a vertical hole 11b, and at the other end to the storage tank 8 via a storage tank connecting channel 13e and a notch 13c. Therefore, if the second switching valve 41 is opened, the piston-side chamber 6 and the storage tank 8 are connected via the second channel 42c; if the second switching valve 41 is closed, the second channel 42c is cut off, and the connection between the piston-side chamber 6 and the storage tank 8 via the second channel 42c is also severed.

[0066] The structure of cylinder device C is as described above. The operation of cylinder device C will be explained below. First, the operation of cylinder device C will be explained with pump 22 stopped and both the first switching valve 40 and the second switching valve 41 closed. With pump 22 stopped and both the first switching valve 40 and the second switching valve 41 closed, cylinder device C functions as a passive damper.

[0067] In cylinder device C, which functions as a passive damper, if telescopic unit 1 extends, piston 4 moves relative to cylinder 2 towards... Figure 2 The piston moves to the left, thus shrinking the rod-side chamber 5 and expanding the piston-side chamber 6. In this case, the check valve 14a, located in the rectifier channel 14, is closed by the pressure of the rod-side chamber 5. Therefore, the liquid in the shrunken rod-side chamber 5 moves to the storage tank 8 through the discharge channel EP formed by the block channel 31e, connecting pipe 18, annular channel P1, through hole 2b, discharge pipe 32 and storage tank channel P2, and the variable pressure reducing valve 30.

[0068] Since the variable pressure reducing valve 30 exerts resistance against such movement of the liquid, the pressure of the rod side chamber 5 is regulated to be higher than the pressure of the liquid tank 8 and equal to the opening pressure of the variable pressure reducing valve 30. In addition, the piston side chamber 6 expands in volume due to the movement of the piston 4, and a liquid deficiency is generated, and the liquid of the deficiency is supplied from the liquid tank 8 to the piston side chamber 6 through the suction passage 19 due to the opening of the check valve 19a. Thus, the pressure of the piston side chamber 6 is substantially equal to the pressure of the liquid tank 8.

[0069] When the telescopic unit 1 performs the extension operation in this manner, the pressure of the rod side chamber 5 acting on the rod side chamber side surface of the piston 4 is higher than the pressure of the piston side chamber 6 acting on the piston side chamber side surface of the piston 4, and the cylinder device C generates an extension side damping force for hindering the extension operation of the telescopic unit 1. In addition, the liquid corresponding to the volume amount of the rod 3 withdrawn from the inside of the cylinder 2 is supplied from the liquid tank 8 to the piston side chamber 6 to compensate for the volume of the rod 3 withdrawn from the inside of the cylinder 2. Further, since the size of the opening pressure of the variable pressure reducing valve 30 can be regulated in accordance with the amount of current supplied to the solenoid 30d, the size of the damping force generated by the cylinder device C when the telescopic unit 1 performs the extension operation can be regulated.

[0070] The liquid accelerates in flow rate when passing through the variable pressure reducing valve 30, reaches the liquid tank 8 through the discharge passage 32 and the liquid tank internal passage P2, but since the liquid decelerates in flow rate when passing through the annular groove 33a of the ring 33 forming the liquid tank internal passage P2, and the outlet end of the liquid tank 8, i.e., the discharge hole 33c of the ring 33 is opened at the lower side of the liquid tank 8, the gas in the liquid tank 8 can be prevented from being entrained in the liquid passing through the variable pressure reducing valve 30, and the gas can be prevented from entering the cylinder 2, so that the good responsiveness of the cylinder device C when generating the damping force can be maintained.

[0071] In addition, the outlet end of the discharge passage EP, i.e., the discharge hole 33c is arranged at the guide side of the liquid tank 8, and by sufficiently spacing the suction passage 19 provided on the bottom cover 13 and the inside of the liquid tank 8, the liquid passing through the variable pressure reducing valve 30 which can possibly entrain the gas when the telescopic unit 1 performs the extension operation can be prevented from being sucked from the liquid tank 8 into the cylinder 2 through the suction passage 19.

[0072] Thus, in the cylinder device C of the present embodiment, the gas can be effectively prevented from entering the cylinder 2, and the good responsiveness of the cylinder device C when generating the damping force can be better maintained.

[0073] Next, the operation when the telescopic unit 1 of the cylinder device C functioning as a passive damper is contracted will be described. When the telescopic unit 1 performs the contraction operation, the piston 4 is withdrawn from the inside of the cylinder 2 with respect to the cylinder 2 toward the Figure 2rightward, the piston-side chamber 6 is reduced in volume and the rod-side chamber 5 is enlarged in volume. In this case, since the check valve 19a provided on the way of the suction passage 19 is closed by the pressure of the piston-side chamber 6, on the other hand, the check valve 14a provided on the way of the straight passage 14 is opened by the pressure of the piston-side chamber 6, and therefore, the liquid in the reduced piston-side chamber 6 moves toward the enlarged rod-side chamber 5 through the straight passage 14.

[0074] Further, when the telescopic unit 1 performs the contraction operation, since the rod 3 enters into the cylinder 2, the liquid in the cylinder 2 is in excess, and the amount of the excess liquid corresponds to the volume amount of the rod 3 entering into the cylinder 2. As in the case of the extension operation, the excess liquid in the cylinder 2 moves toward the liquid reservoir 8 through the discharge passage EP and the variable pressure-reducing valve 30. Since the variable pressure-reducing valve 30 exerts resistance to the movement of such liquid, the pressure of the rod-side chamber 5 is regulated to be higher than the pressure in the liquid reservoir 8 and equal to the opening pressure of the variable pressure-reducing valve 30. Further, since the piston-side chamber 6 is in communication with the rod-side chamber 5 through the straight passage 14, the pressure of the piston-side chamber 6 is substantially equal to the pressure of the rod-side chamber 5.

[0075] When the telescopic unit 1 performs the contraction operation in this manner, the pressure of the rod-side chamber 5 acting on the rod-side chamber side surface of the piston 4 is substantially equal to the pressure of the piston-side chamber 6 acting on the piston-side chamber side surface of the piston 4, but since the pressure-receiving area of the piston 4 receiving the pressure of the rod-side chamber 5 is smaller than the pressure-receiving area of the piston 4 receiving the pressure of the piston-side chamber 6, the cylinder device C generates a compression-side damping force that hinders the contraction operation. Further, since the opening pressure of the variable pressure-reducing valve 30 can be regulated according to the amount of current supplied to the solenoid 30d, the size of the damping force generated by the cylinder device C when the telescopic unit 1 performs the contraction operation can be regulated. In addition, the liquid corresponding to the volume amount of the rod 3 entering into the cylinder 2 is discharged from the cylinder 2 to the liquid reservoir 8 to compensate for the volume of the rod 3 entering into the cylinder 2.

[0076] Thus, the cylinder device C of the present embodiment generates a damping force when performing the extension and contraction operations, thereby functioning as a damper that suppresses the vibration of the vibration object. Further, in the cylinder device C, the cross-sectional area of the rod 3 is made half of the cross-sectional area of the piston 4, and the pressure-receiving area of the rod-side chamber side of the piston 4 is made half of the pressure-receiving area of the piston-side chamber side of the piston 4. Therefore, when the cylinder device C performs the extension and contraction operations, the flow rate of the liquid discharged from the cylinder 2 to the liquid reservoir 8 by the variable pressure-reducing valve 30 is equal. Therefore, if the opening pressures of the variable pressure-reducing valves 30 are the same, the cylinder device C can exhibit the same damping force when the piston 4 moves at the same speed during the extension operation and the contraction operation.

[0077] Next, the operation of the cylinder device C when the pump 22 is stopped and the first on-off valve 40 or the second on-off valve 41 is opened will be described. If the pump 22 is stopped, the first on-off valve 40 is opened and the second on-off valve 41 is closed, the cylinder device C functions as a single-action damper that generates a damping force only when the extension operation is performed, and if the pump 22 is stopped, the first on-off valve 40 is closed and the second on-off valve 41 is opened, the cylinder device C functions as a single-action damper that generates a damping force only when the contraction operation is performed.

[0078] In the case where the pump 22 is stopped and the first on-off valve 40 is opened and the second on-off valve 41 is closed, if the extension operation is performed by the telescopic unit 1, the piston 4 moves to the left in the Figure 2 , and thus the rod-side chamber 5 is reduced and the piston-side chamber 6 is enlarged. The first on-off valve 40 is opened, and the rod-side chamber 5 and the piston-side chamber 6 are communicated through the first passage 42b, the external pipe 50, the branch passage 21h, the supply passage 21f, the connection pipe 17, the annular passage PI, the through-hole 2b, the piston-side chamber communication passage 13d, and the vertical hole lib. Thus, the liquid is freely moved from the rod-side chamber 5 to the piston-side chamber 6. In addition, when the extension operation is performed by the telescopic unit 1, the rod 3 is withdrawn from the inside of the cylinder 2, and thus the liquid corresponding to the volume of the withdrawal is supplied to the reservoir 8 through the suction passage 19. Therefore, since the pressures of the rod-side chamber 5 and the piston-side chamber 6 are equal to the reservoir pressure when the extension operation is performed by the telescopic unit 1, the cylinder device C is in an unloading state, and the extension operation can be performed without resistance.

[0079] Next, the operation of the cylinder device C when the pump 22 is stopped and the first on-off valve 40 is opened and the second on-off valve 41 is closed will be described. If the pump 22 is stopped, the first on-off valve 40 is opened and the second on-off valve 41 is closed, the cylinder device C functions as a single-action damper that generates a damping force only when the extension operation is performed, and if the pump 22 is stopped, the first on-off valve 40 is closed and the second on-off valve 41 is opened, the cylinder device C functions as a single-action damper that generates a damping force only when the contraction operation is performed. Figure 2 , and thus the rod-side chamber 5 is reduced and the piston-side chamber 6 is enlarged. The first on-off valve 40 is opened, and the rod-side chamber 5 and the piston-side chamber 6 are communicated through the first passage 42b, the external pipe 50, the branch passage 21h, the supply passage 21f, the connection pipe 17, the annular passage PI, the through-hole 2b, the piston-side chamber communication passage 13d, and the vertical hole lib. Thus, the liquid is freely moved from the rod-side chamber 5 to the piston-side chamber 6. In addition, when the extension operation is performed by the telescopic unit 1, the rod 3 is withdrawn from the inside of the cylinder 2, and thus the liquid corresponding to the volume of the withdrawal is supplied to the reservoir 8 through the suction passage 19. Therefore, since the pressures of the rod-side chamber 5 and the piston-side chamber 6 are equal to the reservoir pressure when the extension operation is performed by the telescopic unit 1, the cylinder device C is in an unloading state, and the extension operation can be performed without resistance.

[0080] In addition, when the telescopic unit 1 performs the contraction operation, since the rod member 3 enters into the cylinder 2, excess liquid is generated in the cylinder 2, the amount of which corresponds to the volume amount of the rod member 3 entering into the cylinder 2. As in the case of the extension operation, the excess liquid in the cylinder 2 moves to the liquid reservoir 8 through the discharge passage EP and the variable pressure reducing valve 30. Since the variable pressure reducing valve 30 exerts resistance to the movement of such liquid, the pressure of the rod member side chamber 5 is regulated to be higher than the pressure in the liquid reservoir 8 and equal to the opening pressure of the variable pressure reducing valve 30. Further, since the piston side chamber 6 is in a state of communication with the rod member side chamber 5 through the flow regulating passage 14, the pressure of the piston side chamber 6 is substantially equal to the pressure of the rod member side chamber 5.

[0081] Therefore, when the telescopic unit 1 performs the contraction operation in this manner, the pressure of the rod member side chamber 5 acting on the rod member side surface of the piston 4 is substantially equal to the pressure of the piston side chamber 6 acting on the piston side surface of the piston 4, but since the pressure receiving area receiving the pressure of the piston side chamber 6 is larger than the pressure receiving area receiving the pressure of the rod member side chamber 5 of the piston 4, the cylinder device C generates a compression side damping force which hinders the contraction operation. Further, since the size of the opening pressure of the variable pressure reducing valve 30 can be regulated according to the amount of current supplied to the solenoid 30d, the size of the damping force generated by the cylinder device C when the telescopic unit 1 performs the contraction operation can be regulated. In addition, liquid corresponding to the volume amount of the rod member 3 entering into the cylinder 2 is discharged from the cylinder 2 to the liquid reservoir 8 to compensate for the volume of the rod member 3 entering into the cylinder 2.

[0082] Thus, in the case where the pump 22 is stopped and the first on-off valve 40 is opened and the second on-off valve 41 is closed, the cylinder device C functions as a single acting damper which generates a damping force only when the contraction operation is performed.

[0083] On the other hand, in the case where the pump 22 is stopped and the first on-off valve 40 is closed and the second on-off valve 41 is opened, in the cylinder device C, when the telescopic unit 1 performs the extension operation, the piston 4 moves to the left with respect to the cylinder 2 in the drawing, and thus the rod member side chamber 5 is reduced and the piston side chamber 6 is enlarged. In this case, the check valve 14a provided in the middle of the flow regulating passage 14 is closed by the pressure of the rod member side chamber 5, and thus the liquid in the reduced rod member side chamber 5 moves to the liquid reservoir 8 through the discharge passage EP and the variable pressure reducing valve 30. Figure 2

[0084] ​Since the variable pressure reducing valve 30 exerts resistance against such movement of the liquid, the pressure of the rod side chamber 5 is regulated to be higher than the pressure of the liquid tank 8 and equal to the opening pressure of the variable pressure reducing valve 30. In addition, the piston side chamber 6 expands in volume due to the movement of the piston 4, and a liquid deficiency is generated, and the liquid of the deficiency portion is supplied from the liquid tank 8 to the piston side chamber 6 through the second passage 42c, the first passage 42b, the piston side chamber communication passage 13d, the vertical hole lib, the liquid tank communication passage 13e, and the cutout groove 13c due to the opening of the second on-off valve 41. Thus, the liquid is able to move freely from the liquid tank 8 toward the piston side chamber 6, and the pressure of the piston side chamber 6 is substantially equal to the pressure of the liquid tank 8.

[0085] When the telescopic unit 1 performs the extension operation in this manner, the pressure of the rod side chamber 5 acting on the rod side chamber side of the piston 4 becomes higher than the pressure of the piston side chamber 6 acting on the piston side chamber side of the piston 4, and the cylinder device C generates an extension-side damping force for hindering the extension operation of the telescopic unit 1. In addition, the liquid corresponding to the volume amount of the rod 3 withdrawn from the inside of the cylinder 2 is supplied from the liquid tank 8 to the piston side chamber 6 to compensate for the volume of the rod 3 withdrawn from the inside of the cylinder 2. Further, since the size of the opening pressure of the variable pressure reducing valve 30 can be regulated in accordance with the amount of current supplied to the solenoid 30d, the size of the damping force generated by the cylinder device C when the telescopic unit 1 performs the extension operation can be regulated. Thus, the cylinder device C of the present embodiment generates a damping force when performing the telescopic operation, thereby functioning as a damper that suppresses the vibration of the object to be damped.

[0086] Next, the operation when the telescopic unit 1 of the cylinder device C is contracted will be described in the case where the pump 22 is stopped and the first on-off valve 40 is closed and the second on-off valve 41 is opened. When the telescopic unit 1 performs the contraction operation, the piston 4 moves to the right in Fig. 1 with respect to the cylinder 2, and thus the piston side chamber 6 is reduced in volume and the rod side chamber 5 is expanded in volume. In this case, since the second on-off valve 41 is opened, the liquid is able to move freely between the piston side chamber 6 and the liquid tank 8 through the second on-off valve 41. In addition, since the check valve 14a provided on the way of the rectification passage 14 is opened by the pressure of the piston side chamber 6, the liquid in the reduced piston side chamber 6 moves toward the expanded rod side chamber 5 through the rectification passage 14. Figure 5

[0087] ​Furthermore, when the telescopic unit 1 retracts, because the rod 3 enters the cylinder 2, excess liquid is generated in the cylinder 2. The amount of excess liquid is equivalent to the volume of the rod 3 entering the cylinder 2. Since the excess liquid in the cylinder 2 is discharged from the piston-side chamber 6 to the reservoir 8 through the second switching valve 41, the liquid will not pass through the discharge channel EP and the variable pressure reducing valve 30. Therefore, the pressure in the rod-side chamber 5 and the piston-side chamber 6 is the same as the reservoir pressure, the cylinder device C is in an unloaded state, and the retraction action can be performed without resistance.

[0088] Thus, when the pump 22 is stopped and the first switching valve 40 is closed while the second switching valve 41 is opened, the cylinder device C functions as a single-acting damper that generates damping force only during the extension action.

[0089] In addition, as mentioned above, if the first switching valve 40 of the cylinder device C is opened, it is in an unloaded state when performing the extension action; if the second switching valve 41 is opened, it is in an unloaded state when performing the retraction action. Therefore, if both the first switching valve 40 and the second switching valve 41 are opened, it is in an unloaded state on both the extension and retraction sides, and no damping force is generated.

[0090] Next, the operation of cylinder assembly C as an actuator will be explained. First, the case where cylinder assembly C applies thrust in the extension direction will be explained. When telescopic unit 1 extends... ​ When a thrust is applied in the direction of the left-hand push, i.e., in the extension direction, the first switching valve 40 is opened and the second switching valve 41 is closed. Simultaneously, while driving the pump 22, the opening pressure of the variable pressure reducing valve 30 is adjusted to the desired thrust output by the cylinder assembly C. In this state, liquid is supplied from the pump 22 to the rod-side chamber 5. Meanwhile, the first switching valve 40 is open, connecting the rod-side chamber 5 and the piston-side chamber 6. The connection between the piston-side chamber 6 and the reservoir 8 is severed by the closing of the second switching valve 41.

[0091] Liquid is supplied from pump 22 into cylinder 2. Since the pressure in the rod-side chamber 5 and piston-side chamber 6 can be adjusted to be equal to the opening pressure of the variable pressure reducing valve 30, the telescopic unit 1 generates a thrust in the extension direction. The value of this thrust is the product of the difference in the pressure-bearing areas of the rod-side chamber and piston-side chamber of piston 4 and the pressure. Furthermore, the cylinder device C can adjust the pressure in the rod-side chamber 5 and piston-side chamber 6 using the variable pressure reducing valve 30, thus enabling the telescopic unit 1 to exert its own thrust in the extension direction, and also enabling the control of this thrust.

[0092] On the other hand, the case where the cylinder assembly C applies a thrust in the retraction direction will be explained. When the telescopic unit 1 moves towards... ​When a pushing force in the direction of pushing and pressing to the right side, that is, in the contraction direction is applied, the first switching valve 40 is closed, the second switching valve 41 is opened, and the opening pressure of the variable pressure reducing valve 30 is adjusted to the pushing force to be output to the cylinder device C while the pump 22 is driven. In this state, the liquid is supplied from the pump 22 to the rod side chamber 5, the first switching valve 40 is closed, the communication of the rod side chamber 5 and the piston side chamber 6 through the first switching valve 40 is cut off, and the second switching valve 41 is opened, the piston side chamber 6 and the liquid reservoir 8 are communicated through the second switching valve 41.

[0093] In this state, since the first switching valve 40 is closed, the liquid is supplied from the pump 22 only to the rod side chamber 5, on the one hand, the pressure of the rod side chamber 5 is adjusted to the opening pressure of the variable pressure reducing valve 30, on the other hand, since the piston side chamber 6 is communicated with the liquid reservoir 8 through the second switching valve 41, the pressure of the piston side chamber 6 is the reservoir pressure. Therefore, if the reservoir pressure is regarded as 0, the extension and contraction unit 1 generates a pushing force to the right, the value of the force is the value obtained by multiplying the pressure of the rod side chamber 5 by the pressure receiving area of the rod side chamber side of the piston 4. Moreover, the cylinder device C can adjust the pressure of the rod side chamber 5 by the variable pressure reducing valve 30, thus can make the extension and contraction unit 1 generate a pushing force in the contraction direction thereof, and can control the pushing force.

[0094] As described above, the cylinder device C of the present embodiment is provided with: the extension and contraction unit 1 having the cylinder 2, the rod 3 which is axially movably inserted into the cylinder 2, the piston 4 which is axially movably inserted into the cylinder 2 and connected with the rod 3 and which divides the inside of the cylinder 2 into the rod side chamber 5 and the piston side chamber 6, and the housing 7 which is cylindrical and which is arranged at the outer periphery of the cylinder 2 and which forms the liquid reservoir 8 for storing the liquid between the cylinder 2; the pump unit 20 which is provided between the rod side chamber 5 and the liquid reservoir 8 and which has the pump 22 which can supply the liquid from the liquid reservoir 8 to the rod side chamber 5 and the motor 23 for driving the pump 22; the variable pressure reducing valve 30 which is provided between the rod side chamber 5 and the liquid reservoir 8 and which is used to apply resistance to the flow of the liquid flowing from the rod side chamber 5 to the liquid reservoir 8; the first switching valve 40 which is provided between the rod side chamber 5 and the piston side chamber 6; and the second switching valve 41 which is provided between the piston side chamber 6 and the liquid reservoir 8. A part of the passage connecting the rod side chamber 5 and the first switching valve 40 is formed by the external pipe 50 which is arranged outside the housing 7. Since the external pipe 50 is arranged in the unused space between the pump unit 20 and the switching valve unit where no component is originally arranged, the arrangement of the external pipe 50 does not cause the size of the cylinder device C to increase.

[0095] In the cylinder device C according to this configuration, in order to switch the communication and the cutoff of the rod-side chamber 5 and the piston-side chamber 6 by the first switching valve 40, the rod-side chamber 5 and the piston-side chamber 6 need to be communicated, but since a part of the passage connecting the rod-side chamber 5 and the first switching valve 40 is formed by the external pipe 50 arranged outside the housing 7, even if the motor 23 is made large in order to ensure the thrust at the time of high-speed extension and contraction while the capacity of the pump 22 is increased, it is no longer necessary to provide a pipe line covering the entire axial length of the reservoir tank 8 in the housing 7 in order to communicate the rod-side chamber 5 and the piston-side chamber 6, and thus the outer diameter of the housing 7 can be reduced. When the outer diameter of the housing 7 is reduced, the pump unit 20 and the variable pressure reducing valve 30 are arranged at a position radially deviated toward the central side of the cylinder device C by an amount corresponding to the amount by which the outer diameter of the housing 7 is reduced, and the size of the bottom cover 13 closing the end portion of the housing 7 is also reduced in the radial direction, and thus the switching valve unit is also arranged at a position deviated correspondingly toward the central side of the cylinder device C. Further, since the external pipe 50 is arranged in the unused space between the pump unit 20 and the switching valve unit where no component was originally arranged, the arrangement of the external pipe 50 does not cause the size of the cylinder device C to increase. As described above, according to the cylinder device C of the present embodiment, since the external pipe 50 is utilized, even if the motor 23 is made large, it is no longer necessary to provide a pipe line covering the entire axial length of the reservoir tank 8 in the housing 7, and thus the outer diameter of the housing 7 can be reduced to reduce the size of the cylinder device C.

[0096] Thus, according to the cylinder device C of the present embodiment, even if the pump unit 20 is made large, the overall size of the cylinder device C can be prevented from increasing by reducing the diameter of the housing 7, and thus sufficient thrust can be exerted even at high-speed extension and contraction, and good mounting performance can also be achieved. Further, since it is not necessary to provide a passage in the bottom cover 13 to communicate the first switching valve 40 and the rod-side chamber 5, the number of passages provided in the bottom cover 13 can be reduced, which is advantageous in reducing the size of the bottom cover 13.

[0097] Further, the extension and contraction unit 1 of the cylinder device C of the present embodiment is provided with the intermediate cylinder 9 arranged between the cylinder 2 and the housing 7, covering at least a part of the cylinder 2 and forming an annular passage P1 communicating with the rod-side chamber 5 between the cylinder 2, and the pump 22, the variable pressure reducing valve 30, and the first switching valve 40 are connected to the rod-side chamber 5 through the annular passage.

[0098] According to the cylinder device C of this structure, by having the intermediate cylinder 9, it is possible to smoothly form the annular passage P1 that communicates with the rod member side chamber 5 between the cylinder 2 and the housing 7. Also, according to the cylinder device C of this structure, since it is only necessary to connect the pump unit 20 and the variable pressure reducing valve 30 to the annular passage P1, the pump unit 20 and the variable pressure reducing valve 30 can be disposed at any position in the circumferential direction and the axial direction of the outer periphery of the housing 7, so it is possible to optimize the disposition position of the pump unit 20 and the variable pressure reducing valve 30 on the housing 7 according to the disposition object of the cylinder device C, and it is possible to further improve the mounting performance of the cylinder device C. Furthermore, the intermediate cylinder 9 does not necessarily cover the entire length of the cylinder 2 in correspondence with the disposition position of the pump unit 20 and the variable pressure reducing valve 30 on the housing 7, so it is possible to avoid unnecessarily reducing the capacity of the reservoir 8.

[0099] Further, the extension unit 1 of the cylinder device C of the present embodiment also has a base 16 that is installed to the outer periphery of the housing 7 and has a mounting surface 16c on which the pump unit 20 is installed, and a line X that is perpendicular to the mounting surface 16c and passes through the center of the mounting surface 16c and the axis Y of the extension unit 1 are in a twisted position.

[0100] According to the cylinder device C of this structure, the line X that is perpendicular to the mounting surface 16c and passes through the center of the mounting surface 16c and the axis Y of the housing 7 are in a twisted position that does not intersect each other, and since the mounting surface 16c is disposed at an offset position from the housing 7, it is possible to install the pump unit 20 at a position that is offset with respect to the housing 7, the pump unit is installed to the base 16, it is possible to easily avoid interference with other components in the disposition object of the pump unit 20 and the cylinder device C, and further improve the mounting performance of the cylinder device C on the disposition object.

[0101] Furthermore, it is also possible to set the line X that is perpendicular to the mounting surface 16c of the base 16 and passes through the center of the mounting surface 16c to pass through the axis Y of the extension unit 1 without necessarily offsetting the pump unit 20 in the radial direction with respect to the housing 7 of the cylinder device C in this way.

[0102] Further, in the cylinder device C of the present embodiment, the variable pressure reducing valve 30 is installed to the outer periphery of the housing 7, and has a discharge passage EP that communicates the variable pressure reducing valve 30 with the reservoir 8, the discharge passage EP is formed by a discharge pipe 32 that extends from the variable pressure reducing valve 30 into the reservoir 8 and an annular reservoir inner passage P2 that is provided on the ring 33 that fits to the outer periphery of the intermediate cylinder 9 and that communicates with the discharge pipe 32 and communicates at least below the liquid surface in the reservoir 8.

[0103] According to the cylinder device C with this structure, since the flow rate of the liquid passing through the variable pressure reducing valve 30 is reduced from the channel P2 inside the liquid tank, and the liquid is discharged from below the liquid surface S of the liquid O in the liquid tank 8, it is possible to suppress the liquid from carrying away gas in the liquid tank 8 through the variable pressure reducing valve 30, suppress the gas from entering the cylinder 2, and maintain good responsiveness when the cylinder device C generates damping force.

[0104] Furthermore, in the above-described case, the first switching valve 40 is mounted on the bottom cover 13, but if ​ As shown in the cylinder assembly C1 of one variation, when the guide 10 protrudes outward from the end of the housing 7 and the first switching valve 40 is mounted on the guide 10, or when the first switching valve 40 is mounted near the guide 10 on the housing 7, a portion of the passage connecting the first switching valve 40 to the piston-side chamber 6 can be formed using an external pipe 60 disposed on the outside of the housing 7. Alternatively, the first switching valve 40 and the second switching valve 41 can be integrated together in the valve block 42 to form a switching valve unit, but the first switching valve 40 and the second switching valve 41 can also be mounted separately on the telescopic unit 1, or the first switching valve 40 can be integrated into the pump unit 20 or into the valve block 31 for accommodating the variable pressure reducing valve 30.

[0105] The preferred embodiments of the present invention have been described in detail above, but modifications, variations and alterations are possible without departing from the scope of the claims.

[0106] Symbol Explanation

[0107] 1 Telescopic Unit

[0108] 2 cylinders

[0109] 3 rods

[0110] 4 Pistons

[0111] 5. Rod side chamber

[0112] 6 Piston side chamber

[0113] 7. Outer shell

[0114] 8. Liquid storage tank

[0115] 9. Intermediate cylinder

[0116] 16 bases

[0117] 16c mounting surface

[0118] 20 pump units

[0119] 22 pumps

[0120] 23 Motors

[0121] 30 variable pressure reducing valve

[0122] 32 discharge line

[0123] 33 ring

[0124] 40 first on-off valve

[0125] 41 second on-off valve

[0126] 50, 60 external pipe

[0127] C, C1 cylinder device

[0128] EP discharge passage

[0129] O liquid

[0130] P1 annular passage

[0131] P2 passage in liquid storage tank

[0132] S liquid surface

Claims

1. A cylinder device comprising: a telescopic unit having a cylinder, a rod member which is inserted into the cylinder so as to be movable in an axial direction, a piston which is inserted into the cylinder so as to be movable in the axial direction and is coupled to the rod member and which divides an inside of the cylinder into a rod member side chamber and a piston side chamber, and a housing which is cylindrical and is disposed at an outer periphery of the cylinder so as to form a liquid storage tank for storing a liquid between the cylinder; a pump unit which is provided between the rod member side chamber and the liquid storage tank and has a pump which is capable of supplying the liquid from the liquid storage tank toward the rod member side chamber and a motor which is used to drive the pump; a variable pressure reducing valve which is provided between the rod member side chamber and the liquid storage tank and which is used to apply a resistance to a flow of the liquid flowing from the rod member side chamber toward the liquid storage tank; a first on-off valve which is provided between the rod member side chamber and the piston side chamber; a second on-off valve which is provided between the piston side chamber and the liquid storage tank; and a part of a passage which connects the rod member side chamber and the first on-off valve or a part of a passage which connects the piston side chamber and the first on-off valve is formed by an external pipe which is disposed outside the housing.

2. The cylinder device according to claim 1, wherein the telescopic unit has an intermediate cylinder which is provided between the cylinder and the housing, covers at least a part of the cylinder and forms an annular passage which communicates with the rod member side chamber between the cylinder, the pump, the variable pressure reducing valve and the first on-off valve are connected to the rod member side chamber through the annular passage.

3. The cylinder device according to claim 2, wherein the variable pressure reducing valve is mounted to an outer periphery of the housing, an exhaust passage which communicates the variable pressure reducing valve with the liquid storage tank is provided, the exhaust passage is formed by an exhaust pipe and an annular liquid storage tank inner passage, the exhaust pipe extends from the variable pressure reducing valve into the liquid storage tank, the liquid storage tank inner passage is provided on a ring which is fitted to the outer periphery of the intermediate cylinder, communicates with the exhaust pipe and communicates with at least a lower side of a liquid surface of the liquid in the liquid storage tank. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

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