CN116658560A

CN116658560A - Cylinder device

Info

Publication number: CN116658560A
Application number: CN202210904528.6A
Authority: CN
Inventors: 山崎晋平
Original assignee: KYB Corp
Current assignee: KYB Corp
Priority date: 2022-02-17
Filing date: 2022-07-29
Publication date: 2023-08-29
Also published as: JP2023119628A

Abstract

The cylinder device of the present invention comprises: a telescoping unit; a liquid storage tank; the actuator circuit and the shock absorber circuit are arranged between the cylinder and the liquid storage tank of the telescopic unit, the actuator circuit is provided with a thrust adjusting part which is arranged on a control channel which communicates the rod piece side chamber with the liquid storage tank, and the shock absorber circuit is provided with a compression side pressure reducing valve on a compression side damping channel which connects the piston side chamber to the thrust adjusting part.

Description

Cylinder device

Technical Field

The present invention relates to a cylinder device.

Background

Conventionally, a cylinder device generates thrust, drives an object to which the thrust acts, assists displacement of the object, and suppresses vibration of the object. For example, when the body of the railway vehicle is the object, the cylinder device is horizontally mounted between the body of the railway vehicle and the bogie, and suppresses the left-right direction vibration with respect to the advancing direction of the body. Further, the cylinder device may be used, for example, as an actuator that actively applies a thrust force to the vehicle body to suppress vibration of the vehicle body, or as a damper that generates a damping force to suppress vibration of the vehicle body when the vehicle body vibrates to expand and contract.

Such a cylinder device is provided with, for example, as disclosed in JP 2016-060438A: a cylinder; a rod freely movably inserted into the cylinder; a piston movably inserted into the cylinder, coupled with the rod, and dividing the cylinder into a rod-side chamber filled with hydraulic oil and a piston-side chamber; the liquid storage tank is used for storing hydraulic oil; a first switching valve provided on a first passage that communicates the rod-side chamber with the piston-side chamber; a second switching valve provided on a second passage that communicates the piston-side chamber with the reservoir; a pump that supplies liquid to the rod-side chamber; a motor that drives a pump; a discharge passage that communicates the rod-side chamber with the liquid tank; a variable pressure reducing valve provided in the discharge passage, the variable pressure reducing valve being capable of changing a valve opening pressure; a rectifying passage that allows only a flow of liquid from the piston-side chamber to the rod-side chamber; and a suction passage that allows only the liquid flow of the liquid reservoir to the piston-side chamber.

The cylinder device thus constructed is configured to enter a damper mode after the first and second switching valves are closed by the stop pump, and is used as a one-way flow type damper in which hydraulic oil sequentially passes through the liquid storage tank, the piston-side chamber, the rod-side chamber and reaches the liquid storage tank after an external force is applied to perform a telescoping action. Further, the cylinder device applies a resistance to the flow of the hydraulic oil discharged from the cylinder through the discharge passage to the reservoir tank when the expansion and contraction operation is performed by the variable relief valve, and generates a damping force that hinders the expansion and contraction.

Disclosure of Invention

Problems to be solved by the invention

As described above, the conventional cylinder device can be used as an actuator or a damper as needed, and can be used as a one-way flow damper in the damper mode. In the shock absorber mode cylinder device, hydraulic oil is discharged from within the contracted rod-side chamber through the variable relief valve to the reservoir tank when the extension operation is performed, and hydraulic oil is supplied from the reservoir tank to the expanded piston-side chamber via the suction passage. Therefore, when the shock absorber mode cylinder device performs the extension operation, the rod side chamber pressure raised by the variable relief valve acts on the pressure receiving surface of the piston facing the rod side chamber, and the tank pressure acts on the pressure receiving surface of the piston facing the piston side chamber. When the reservoir pressure is set to 0, a damping force is generated when the shock absorber mode cylinder device executes an extension operation, and the damping force is the number of the rod side chamber internal pressure multiplied by the rod side chamber side pressure receiving area of the piston.

On the other hand, when the shock absorber mode cylinder device performs the contracting action, the hydraulic oil moves from the contracted piston-side chamber to the rod-side chamber through the rectifying passage, and the volume amount of the hydraulic oil that the rod enters the cylinder is discharged from the cylinder to the reservoir through the variable relief valve. Therefore, when the damper mode cylinder device performs the contracting operation, the in-cylinder pressure raised by the variable relief valve acts equally on the rod side chamber side pressure receiving surface and the piston side chamber side pressure receiving surface of the piston, respectively. The difference between the pressure receiving area of the rod side chamber side of the piston and the pressure receiving area of the piston side chamber side is equal to the sectional area of the rod, so that the shock absorber mode cylinder device generates damping force when executing the contraction action, and the value is the in-cylinder pressure multiplied by the sectional area of the rod.

Since the cylinder device is used to suppress the left-right vibration of the vehicle body with respect to the carriage, if the damping force when the extension operation is performed and the damping force when the contraction operation is performed are deviated, the vehicle body is deviated in the operation direction in which the damping force is small with respect to the carriage during the repeated extension and retraction, which is not preferable. Therefore, the cylinder device used as a one-way flow type shock absorber sets the rod cross-sectional area to one half of the piston cross-sectional area, and as long as the stroke amount in the cylinder is the same, hydraulic oil having the same flow rate can pass through the variable relief valve, and the same damping force can be generated when the extension motion is performed and when the contraction motion is performed. In summary, in the conventional cylinder device, the rod diameter and the piston diameter are limited in design.

Here, the hydraulic oil, which is a working medium of the cylinder device, has viscoelasticity, and if the damping coefficient of the cylinder device is to be increased to generate a large damping force, the rigidity of the oil column is to be increased. In order to increase the rigidity of the oil column, the pressure receiving area of the piston is increased, so that the diameter of the cylinder is only increased, but in this way, the diameter of the rod is also increased, and the cylinder device possibly collides with other equipment of the railway vehicle, so that the diameter of the cylinder is difficult to increase.

On the other hand, in the two-way flow shock absorber, the expansion-side damping force is generated by applying resistance to the flow of hydraulic oil moving from the rod-side chamber to the piston-side chamber by the expansion-side pressure reducing valve during expansion, the compression-side damping force is generated by applying resistance to the flow of hydraulic oil moving from the piston-side chamber to the reservoir by the compression-side pressure reducing valve during contraction, and the expansion-side damping force and the compression-side damping force can be arbitrarily set by the expansion-side pressure reducing valve and the compression-side pressure reducing valve, respectively, so that the damping coefficient can be improved without increasing the cylinder diameter. However, in the two-way flow type shock absorber, when hydraulic oil is supplied to the piston-side chamber, the hydraulic oil escapes from the compression-side pressure reducing valve into the reservoir tank, and is difficult to use as an actuator.

As described above, the conventional cylinder device has problems such as an increase in the size of the cylinder device and a problem in use as an actuator when the damping coefficient is increased. In addition, such problems are not only present in the cylinder devices used in railway vehicles, but also in the case where the object to which the thrust force of the cylinder device acts is a vehicle other than railway vehicles, a structure, a machine, or the like, but also in the case where the cylinder device is increased in size or used as an actuator to increase the damping coefficient.

Accordingly, an object of the present invention is to provide a cylinder device capable of improving a damping coefficient when used as a shock absorber while functioning as an actuator without increasing the size.

Means for solving the problems

The cylinder device of the present invention comprises: the telescopic unit is provided with a cylinder, a rod and a piston, wherein the rod is movably inserted into the cylinder, and the piston is movably inserted into the cylinder and is connected with the rod to divide the cylinder into a rod side chamber and a piston side chamber; a liquid storage tank; an actuator circuit having a pump that can supply liquid from a tank to a cylinder, an adjustment passage that communicates a rod-side chamber with the tank and is provided with a variable pressure-reducing valve in the middle, and a bypass passage that communicates the rod-side chamber with the tank and is provided with a pressure-reducing valve and a bypass passage switching valve in the middle in series, and that can drive the expansion unit to expand and contract; and a shock absorber circuit including an extension side damping passage that communicates the rod side chamber with the piston side chamber, an extension side damping valve that is provided on the extension side damping passage and that applies resistance to liquid flow from the rod side chamber to the piston side chamber, a compression side damping passage that connects the piston side chamber between the pressure reducing valve of the bypass passage and the bypass passage switching valve, that is provided on the compression side damping passage and that applies resistance to liquid flow from the piston side chamber to the reservoir tank, a suction passage that communicates the reservoir tank with the piston side chamber, and a suction check valve that is provided on the suction passage and that allows liquid flow from the reservoir tank to the piston side chamber, the variable pressure reducing valve and the bypass passage switching valve being solenoid valves driven by the same solenoid, the variable pressure reducing valve being adjustable in opening valve pressure when the solenoid is energized, the bypass passage switching valve being closed when the solenoid is energized and being opened when the solenoid is not energized, closing the bypass passage switching valve when the actuator mode of the pump is driven to open the bypass passage switching valve to thereby open the bypass passage.

The cylinder device of the present embodiment thus constructed can be used as an actuator or a shock absorber, and when used as a shock absorber, the damping force characteristics when the extension operation is performed and the damping force characteristics when the contraction operation is performed can be set to the same characteristics by the setting of the extension-side pressure reducing valve and the compression-side pressure reducing valve, regardless of the setting of the rod diameter and the cylinder diameter.

Further, the cylinder device thus constituted can supply the liquid from the pump to the cylinder by the actuator circuit, cut off the compression-side damping passage by the bypass passage switching valve to serve as an actuator, and stop the pump from opening the compression-side damping passage by the bypass passage switching valve to serve as a shock absorber by the shock absorber circuit. When the cylinder device thus configured is used as a shock absorber, the expansion-side pressure reducing valve can be used to generate a damping force when the expansion unit performs an expansion operation, and the compression-side pressure reducing valve can be used to generate a damping force when the expansion unit performs a contraction operation.

Further, another cylinder device according to the present invention includes: the telescopic unit is provided with a cylinder, a rod and a piston, wherein the rod is movably inserted into the cylinder, and the piston is movably inserted into the cylinder and is connected with the rod to divide the cylinder into a rod side chamber and a piston side chamber; a liquid storage tank; an actuator circuit having a pump that can supply liquid from the liquid tank to the cylinder, a control passage that communicates the rod-side chamber with the liquid tank, and a thrust adjustment portion provided on the control passage, and that can drive the expansion unit to expand and contract; and a shock absorber circuit including an extension side damping passage that communicates the rod side chamber with the piston side chamber, an extension side damping valve that is provided on the extension side damping passage and that applies resistance to a liquid flow from the rod side chamber to the piston side chamber, a compression side damping passage that connects the piston side chamber to a thrust adjustment portion that is provided on the compression side damping passage and that applies resistance to a liquid flow from the piston side chamber to the reservoir tank, a suction passage that communicates the reservoir tank with the piston side chamber, a suction check valve that is provided on the suction passage and that allows a liquid flow from the reservoir tank to the piston side chamber, a thrust adjustment portion that has an adjustment passage that is provided midway on a control passage, a pressure reducing valve that opens when the rod side chamber side pressure reaches a valve opening pressure, a pressure reducing valve that can be adjusted by energization, and a pressure reducing valve that can be adjusted by energization is provided on the adjustment passage from the rod side chamber to the reservoir tank side chamber and the piston side chamber, and a pressure reducing valve that can be connected in series between the compression side chamber and the compression side damping valve.

In the present invention, the cylinder device is configured to be used as a damper, and the damping force characteristic when the expansion operation is performed and the damping force characteristic when the contraction operation is performed can be set to be the same by the setting of the expansion side pressure reducing valve and the compression side pressure reducing valve, regardless of the setting of the rod diameter and the cylinder diameter.

In the cylinder device having the above configuration, even if the thrust adjustment unit does not have the switching valve for shutting off the compression-side damping passage in the actuator mode, the compression-side damping force can be generated by the compression-side pressure reducing valve in the shock absorber mode, and the thrust adjustment unit can be simply configured without the switching valve, so that the manufacturing cost can be reduced.

Drawings

Fig. 1 is a circuit diagram of a cylinder device of a first embodiment.

Fig. 2 is a diagram showing a state in which the cylinder device is mounted between the body of the railway vehicle and the bogie.

Fig. 3 is a circuit diagram of the cylinder device of the second embodiment.

Detailed Description

The present invention will be described below based on the embodiments shown in the drawings. In the cylinder device according to each embodiment, the common reference numeral means and members have the same configuration. Therefore, in order to avoid repetitive description, the cylinder device description of one embodiment is described in detail, and the cylinder device description of the other embodiment is not described in detail. In the description of the cylinder device of the present invention, the cylinder device applied to the railway vehicle is described as an example, but the cylinder device of the present invention may be used for driving a vehicle other than the railway vehicle, a structure, a building, a machine, or the like, and suppressing vibration.

< first embodiment >

The present invention will be described below based on the embodiments shown in the drawings. As shown in fig. 1, the cylinder device C of the first embodiment includes and is constituted by: a telescopic unit 1, a reservoir 7, an actuator circuit a, a damper circuit D. As shown in fig. 2, in the present embodiment, 2 cylinder devices C are installed in parallel between the body S of the railway vehicle T and the bogie B to suppress the horizontal vibration of the body S, but 1 cylinder device C may be installed between the body S and the bogie B to be used.

Next, each portion of the cylinder device C will be described. The expansion unit 1 includes: a cylinder 2; a rod 3, the rod 3 being movably inserted into the cylinder 2; a piston 4, the piston 4 is movably inserted into the cylinder 2 and connected with the rod 3, dividing the cylinder 2 into a rod side chamber 5 and a piston side chamber 6.

In addition, the rod-side chamber 5 and the piston-side chamber 6 are filled with hydraulic oil as a liquid, and in addition, the reservoir tank 7 is filled with a gas in addition to the hydraulic oil. Besides hydraulic oil, water and aqueous solutions may also be used for the liquid. The inside of the liquid reservoir 7 is not particularly required to be pressurized by compressing and filling with gas, but may be pressurized.

The cylinder 2 has a cylindrical shape, the right end of which is closed by a cover 19 in fig. 1, and the left end of which is fitted with an annular rod guide 20 in fig. 1. Further, the rod 3 freely movably inserted into the cylinder 2 is movably inserted into the inner circumference of the rod guide 20. One end of the rod 3 is coupled to a piston 4 movably inserted into the cylinder 2, and the other end protrudes out of the cylinder 2 and is axially movable with respect to the cylinder 2.

The cylinder device C further includes an outer tube 21 covering the outer periphery of the cylinder 2. The left and right ends of the outer tube 21 in fig. 1 are closed by the cover 19 and the rod guide 20 as with the cylinder 2, and the reservoir tank 7 is formed by an annular gap between the outer tube 21 and the cylinder 2. A cover 19 closing the left end of the rod 3 and the right end of the cylinder 2 in fig. 1 is provided with a mounting portion, not shown, and the cylinder device C can be mounted between the body S of the railway vehicle T and the carriage B.

The actuator circuit a is a circuit that includes a pump 14 to drive the expansion unit 1 to expand and contract, and the pump 14 is provided between the cylinder 2 and the reservoir 7 and is capable of supplying hydraulic oil from the reservoir 7 to the cylinder 2. After driving the pump 14, the actuator circuit a supplies hydraulic oil into the cylinder 2, selects one of the expansion direction and the contraction direction of the expansion unit 1, and adjusts the thrust force generated by the expansion unit 1 in the selected direction.

Specifically, as shown in fig. 1, the actuator circuit a includes: a pump 14, the pump 14 being provided between the cylinder 2 and the reservoir 7, for supplying hydraulic oil to the rod-side chamber 5; a motor 15, said motor 15 driving the pump 14; a control passage 40, the control passage 40 communicating the rod-side chamber 5 with the liquid reservoir 7; a thrust adjustment portion FT provided in the control passage 40; a first passage 10, the first passage 10 communicating the rod-side chamber 5 with the piston-side chamber 6; a first on-off valve 11, the first on-off valve 11 being provided on the first passage 10; a second passage 12, the second passage 12 communicating the piston-side chamber 6 with the reservoir 7; a second switching valve 13, the second switching valve 13 being disposed on the second passage 12.

The pump 14 is driven by a motor 15, and hydraulic oil is discharged in only one direction in the cylinder device C of the present embodiment. The discharge port of the pump 14 communicates with the rod-side chamber 5 through a supply passage 22 that communicates the rod-side chamber 5 with the liquid reservoir 7, and the suction port communicates with the liquid reservoir 7 through the supply passage 22. Therefore, the pump 14 is driven by the motor 15, and then sucks hydraulic oil from the reservoir tank 7 and supplies the hydraulic oil to the rod side chamber 5.

As described above, since the pump 14 discharges the hydraulic oil only in one direction and does not switch the rotation direction, there is no problem that the discharge amount changes when switching the rotation, and a low-cost gear pump or the like can be used. Further, since the rotation direction of the pump 14 is always the same, the motor 15, which is a driving source for driving the pump 14, is not required to have high response to the switching rotation, and accordingly, a low-cost motor can be used for the motor 15. In addition, a check valve 23 that prevents the hydraulic oil from flowing back from the rod-side chamber 5 to the pump 14 is provided on the supply passage 22.

In the actuator circuit a of the present embodiment, a first on-off valve 11 is provided in a first passage 10 that communicates the rod-side chamber 5 with the piston-side chamber 6, and a second on-off valve 13 is provided in a second passage 12 that communicates the piston-side chamber 6 with the reservoir 7.

In the present embodiment, the first switching valve 11 is an electromagnetic switching valve, and includes and is constituted by: a valve body 11a, the valve body 11a having a communication position 11b and a shut-off position 11c, the communication position 11b opening the first passage 10 to communicate the rod-side chamber 5 with the piston-side chamber 6, the shut-off position 11c shutting off communication between the rod-side chamber 5 and the piston-side chamber 6; a spring 11d, the spring 11d applying a force to the valve body 11a to select the cut-off position 11c; a solenoid 11e that, when energized, switches the valve body 11a to the communication position 11b against the spring 11 d.

In the present embodiment, the second on-off valve 13 is an electromagnetic on-off valve, and includes and is constituted by: a valve body 13a, the valve body 13a having a communication position 13b and a shut-off position 13c, the communication position 13b opening the second passage 12 to communicate the piston-side chamber 6 with the reservoir 7, the shut-off position 13c shutting off communication between the piston-side chamber 6 and the reservoir 7; a spring 13d, the spring 13d applying a force to the valve body 13a to select the cut-off position 13c; a solenoid 13e that, when energized, opposes the spring 13d to switch the valve body 13a to the communication position 13b.

The thrust adjustment unit FT includes: a tuning passage P1 and a bypass passage P2, the tuning passage P1 and the bypass passage P2 being connected in parallel to the midway of the control passage 40 that communicates the rod-side chamber 5 with the reservoir 7; a variable pressure reducing valve 41, the variable pressure reducing valve 41 being provided on the adjustment passage P1; a pressure reducing valve 43 and a bypass passage switching valve 44, which pressure reducing valve 43 and bypass passage switching valve 44 are provided in series in this order on the bypass passage P2 from the rod-side chamber 5 side.

In this way, in the cylinder device C of the first embodiment, the rod-side chamber 5 and the liquid reservoir 7 are connected through the control passage 40, the adjustment passage P1 and the bypass passage P2 provided midway in the control passage 40. As described above, the variable relief valve 41 that can change the valve opening pressure is provided in the adjustment passage P1, and the relief valve 43 and the bypass passage switching valve 44 are provided in series in the bypass passage P2.

The pressure reducing valve 43 includes and is constituted by: a valve body 43a, the valve body 43a being disposed on the bypass passage P2; a spring 43b, the spring 43b biasing the valve body 43a to shut off the bypass passage P2; a pilot passage 43c for applying a rod-side chamber side pressure on an upstream side of the valve body 43a to the valve body 43a so as to urge the spring 43b in a valve opening direction. The valve opening pressure of the relief valve 43 is set to a valve opening pressure specified in advance in accordance with the urging force of the spring 43b against the valve body 43 a.

When the pressure in the rod-side chamber 5 upstream of the bypass passage P2 acting on the valve body 43a exceeds the pressure of the pressure reduction valve 43 (valve opening pressure) in the open state of the bypass passage switching valve 44 provided downstream of the pressure reduction valve 43, the force pushing the valve body 43a overcomes the urging force of the spring 43b on the valve body 43a, the valve body 43a retreats, and the pressure reduction valve 43 opens the bypass passage P2.

The bypass passage switching valve 44 includes and is constituted by: a valve body 44a, the valve body 44a being provided downstream of the pressure reducing valve 43 of the bypass passage P2, i.e., on the tank side and being openable and closable; a spring 44b, the spring 44b biasing the valve body 44a to open the bypass passage P2; a solenoid Sol that generates a thrust force against the spring 44b when energized, and switches the valve body 44a to a position that shuts off the bypass passage P2. As described above, the bypass passage switching valve 44 is a solenoid valve, and when a current equal to or greater than a predetermined value is applied to the solenoid Sol, the solenoid Sol generates a thrust force exceeding the biasing force of the spring 44b, and the bypass passage P2 is shut off.

When no current is supplied to the solenoid Sol, the valve body 44a of the bypass passage switching valve 44 is biased by the spring 44b, and the bypass passage P2 is opened. That is, when the solenoid Sol is not energized, the bypass passage switching valve 44 is opened, and the bypass passage P2 is opened.

The variable pressure reducing valve 41 includes and is constituted by: a valve body 41a, the valve body 41a being disposed on the adjustment passage P1; a spring 41b, wherein the spring 41b biases the valve body 41a to cut off the adjustment passage P1; a pilot passage 41c for applying a rod-side chamber side pressure on an upstream side of the valve body 41a to the valve body 41a so as to urge the spring 41b in a valve opening direction; a solenoid Sol that generates a thrust force against the spring 41b when energized. The variable relief valve 41 is a solenoid valve, and the valve opening pressure can be adjusted by adjusting the amount of current flowing through the solenoid Sol. In addition, the thrust of the solenoid Sol is transmitted to the valve body 41a of the variable relief valve 41 through the valve body 44 a. More specifically, when a current equal to or greater than a predetermined value is supplied to the solenoid Sol, the valve body 44a of the bypass passage switching valve 44 cuts off the bypass passage P2, and contacts the valve body 41a of the variable relief valve 41, thereby transmitting the thrust of the solenoid Sol to the valve body 41a.

When the pressure in the rod-side chamber 5 upstream of the control passage 40 acting on the valve body 41a exceeds the relief pressure (valve opening pressure) of the variable relief valve 41, the pressure and the force of the solenoid Sol pushing the valve body 41a cancel the resultant force of the urging force of the spring 41b against the valve body 41a and the urging force of the spring 44b against the valve body 44a, the valve body 41a retreats, and the variable relief valve 41 opens the adjustment passage P1.

Further, with the variable relief valve 41, if the amount of current supplied to the solenoid Sol is increased, the thrust generated by the solenoid Sol can be increased. Therefore, when the amount of current supplied to the solenoid Sol is adjusted to the maximum, the valve opening pressure of the variable relief valve 41 becomes the minimum, whereas when no current is supplied to the solenoid Sol at all, the valve opening pressure of the variable relief valve 41 becomes the maximum. When the amount of current supplied to the solenoid Sol is adjusted to a predetermined value or more and the amount of current is changed, the valve opening pressure of the variable relief valve 41 can be changed while the bypass passage switching valve 44 is closed. Thus, the variable relief valve 41 and the bypass passage switching valve 44 are solenoid valves that share 1 solenoid Sol and are driven by the same solenoid Sol. Accordingly, the thrust force of the solenoid Sol can be applied to the respective valve bodies 41a,44a of the variable relief valve 41 and the bypass passage switching valve 44, respectively.

When the solenoid Sol is energized, the opening pressure of the variable relief valve 41 can be adjusted according to the amount of current supplied to the solenoid Sol, and the bypass passage switching valve 44 can be closed. Conversely, when no current is supplied to the solenoid Sol, the valve opening pressure of the variable relief valve 41 is maximized and the bypass passage switching valve 44 is opened.

Further, regardless of the on/off states of the first and second on/off valves 11 and 13, when an excessive input is made to the expansion/contraction unit 1 in the expansion/contraction direction, the pressure in the rod side chamber 5 exceeds the valve opening pressure, and the variable pressure reducing valve 41 opens the adjustment passage P1 to communicate the rod side chamber 5 with the liquid tank 7. In this way, for an excessive input to the telescopic unit 1, the variable relief valve 41 discharges the pressure in the rod-side chamber 5 to the liquid tank 7, protecting the entire system of the cylinder device C.

Next, the damper circuit D includes: an extension-side damping passage 24, the extension-side damping passage 24 communicating the rod-side chamber 5 with the piston-side chamber 6; an extension-side pressure reducing valve 25 provided on the extension-side damping passage 24, which exerts resistance to the flow of hydraulic oil from the rod-side chamber 5 to the piston-side chamber 6; a compression-side damping passage 26, the compression-side damping passage 26 connecting the piston-side chamber 6 to the thrust adjustment portion FT; a first compression-side pressure reducing valve 27, the first compression-side pressure reducing valve 27 being provided as a compression-side pressure reducing valve on the compression-side damping passage 26, imparting resistance to the flow of hydraulic oil from the piston-side chamber 6 to the reservoir 7; a suction passage 28, the suction passage 28 communicating the reservoir 7 with the piston-side chamber 6; a suction check valve 29 provided on the suction passage 28, allowing the hydraulic oil of the reservoir tank 7 to the piston-side chamber 6 to flow; an elongated side suction passage 30, the elongated side suction passage 30 communicating the liquid reservoir 7 with the rod side chamber 5; an extension-side check valve 31 provided on the extension-side suction passage 30, allowing only the hydraulic oil of the reservoir tank 7 to the rod-side chamber 5 to flow; a compression-side passage 32, the compression-side passage 32 communicating the piston-side chamber 6 with the rod-side chamber 5; a second compression-side pressure reducing valve 33, the second compression-side pressure reducing valve 33 being provided on the compression-side passage 32, imparting resistance to the flow of hydraulic oil from the piston-side chamber 6 to the rod-side chamber 5.

An extension-side damping passage 24 is provided on the piston 4, communicating the rod-side chamber 5 with the piston-side chamber 6. Further, the extension-side pressure reducing valve 25 is provided in the piston 4, and if the pressure in the rod-side chamber 5 exceeds the pressure in the piston-side chamber 6, and the difference between the pressure in the rod-side chamber 5 and the pressure in the piston-side chamber 6 reaches the valve opening pressure, the extension-side pressure reducing valve 25 opens, and applies resistance to the flow of hydraulic oil from the rod-side chamber 5 to the piston-side chamber 6. In addition, for the flow of hydraulic oil from the piston-side chamber 6 to the rod-side chamber 5 in the extension-side damper passage 24, the extension-side pressure reducing valve 25 is closed, shutting off the extension-side damper passage 24. Therefore, the extension-side damping passage 24 is set as a one-way passage that allows only the hydraulic oil of the rod-side chamber 5 to the piston-side chamber 6 to flow using the extension-side pressure reducing valve 25.

The valve opening pressure of the expansion-side pressure reducing valve 25 is set to be equal to or higher than the difference between the pressure in the rod-side chamber 5 and the pressure in the piston-side chamber 6 when the expansion unit 1 generates the maximum thrust to the contraction side by the actuator circuit a. Therefore, even if the pump 14 of the actuator circuit a is driven to generate the maximum thrust in the retraction direction of the extension unit 1, the extension-side pressure reducing valve 25 is not opened, and the state of shutting off the extension-side damping passage 24 is maintained.

The compression-side damping passage 26 connects the piston-side chamber 6 to the thrust adjustment portion FT. Specifically, the compression-side damping passage 26 connects the piston-side chamber 6 between the relief valve 43 and the bypass passage switching valve 44 of the bypass passage P2. Therefore, when the bypass passage switching valve 44 is in the open state, the piston side chamber 6 communicates with the reservoir 7 via the compression side damping passage 26, the bypass passage switching valve 44, the bypass passage P2, and the thrust adjustment portion FT of the control passage 40 downstream. When the bypass passage switching valve 44 is in the closed state, communication between the piston side chamber 6 and the reservoir 7 via the compression side damper passage 26 is cut off. The compression-side damper passage 26 is connected between the pressure reducing valve 43 and the bypass passage switching valve 44 of the bypass passage P2, so that the shut-off and communication of the compression-side damper passage 26 can be switched by the switching of the bypass passage switching valve 44 disposed downstream of the compression-side damper passage 26.

When the bypass passage switching valve 44 is opened, if the pressure in the piston-side chamber 6 exceeds the pressure in the reservoir tank 7, and the difference between the pressure in the piston-side chamber 6 and the pressure in the reservoir tank 7 reaches the opening pressure, the first compression-side pressure reducing valve 27, which is a compression-side pressure reducing valve, is opened, and resistance is applied to the flow of hydraulic oil from the piston-side chamber 6 to the reservoir tank 7. In addition, for the flow of the hydraulic oil from the reservoir 7 to the piston side chamber 6 in the compression side damping passage 26, the first compression side pressure reducing valve 27 is closed, shutting off the compression side damping passage 26. Therefore, the compression-side damping passage 26 is set as a one-way passage that allows only the hydraulic oil of the piston-side chamber 6 to the reservoir 7 to flow using the first compression-side relief valve 27. When the bypass passage switching valve 44 is closed, the communication between the piston-side chamber 6 and the reservoir 7 via the compression-side damper passage 26 is shut off, and therefore the first compression-side pressure reducing valve 27 is not opened.

Next, the suction passage 28 communicates the reservoir tank 7 with the piston-side chamber 6. Further, if the pressure in the reservoir tank 7 exceeds the pressure in the piston-side chamber 6, the suction check valve 29 opens, and the hydraulic oil from the reservoir tank 7 to the piston-side chamber 6 is allowed to pass without exerting too much resistance. In addition, for the flow of the hydraulic oil from the piston-side chamber 6 to the reservoir 7 in the suction passage 28, the suction check valve 29 is closed, shutting off the suction passage 28. Therefore, the suction passage 28 is set as a one-way passage that allows only the hydraulic oil of the reservoir tank 7 to the piston-side chamber 6 to flow by the suction check valve 29.

Further, the extension-side suction passage 30 communicates the liquid reservoir 7 with the rod-side chamber 5. Further, if the pressure in the reservoir tank 7 exceeds the pressure in the rod side chamber 5, the extension side check valve 31 opens, and does not exert too much resistance, allowing the passage of the hydraulic oil from the reservoir tank 7 to the rod side chamber 5. In addition, for the flow of the hydraulic oil from the rod side chamber 5 to the reservoir 7 in the extension side suction passage 30, the extension side check valve 31 is closed, shutting off the extension side suction passage 30. Therefore, the extension-side suction passage 30 is set as a one-way passage that allows only the hydraulic oil of the reservoir tank 7 to the rod-side chamber 5 to flow using the extension-side check valve 31.

Further, a compression-side passage 32 is provided on the piston 4, communicating the piston-side chamber 6 with the rod-side chamber 5. Further, the second compression-side pressure reducing valve 33 is provided in the piston 4, and if the pressure in the piston-side chamber 6 exceeds the pressure in the rod-side chamber 5, and the difference between the pressure in the piston-side chamber 6 and the pressure in the rod-side chamber 5 reaches the valve opening pressure, the second compression-side pressure reducing valve 33 opens, and applies resistance to the flow of hydraulic oil from the piston-side chamber 6 to the rod-side chamber 5. In addition, with respect to the flow of the hydraulic oil from the rod side chamber 5 to the piston side chamber 6 in the compression side passage 32, the second compression side pressure reducing valve 33 is closed, shutting off the compression side passage 32. Therefore, the compression-side passage 32 is set as a one-way passage that allows the flow of hydraulic oil only from the piston-side chamber 6 to the rod-side chamber 5 by the second compression-side pressure reducing valve 33.

The cylinder device C is configured as described above, and the operation of the cylinder device C will be described below. First, an actuator mode in which the cylinder device C is used as an actuator by the actuator circuit a will be described. When the cylinder device C is caused to generate thrust in the extension direction, the first switching valve 11 is adjusted to the communication position 11b, the second switching valve 13 is adjusted to the shutoff position 13C, the pump 14 is driven by the motor 15, and the hydraulic oil is supplied from the reservoir tank 7 into the cylinder 2. Further, a current equal to or higher than a predetermined value is applied to the solenoid Sol, the bypass passage switching valve 44 is closed, the bypass passage P2 is shut off, and the valve opening pressure of the variable relief valve 41 is adjusted in accordance with the thrust force that the cylinder device C needs to exert.

In this way, after the first on-off valve 11 is opened, the rod-side chamber 5 and the piston-side chamber 6 are placed in communication through the first passage 10, and hydraulic oil is supplied from the pump 14 to the rod-side chamber 5 and the piston-side chamber 6. Further, the bypass passage switching valve 44 is closed, so the compression-side damping passage 26 is shut off, and therefore the hydraulic oil supplied into the cylinder 2 cannot move from the piston-side chamber 6 to the reservoir tank 7. In this way, when the cylinder device C is used as the actuator mode of the actuator, the compression-side damping passage 26 is shut off by the bypass passage switching valve 44.

Therefore, when the first switching valve 11 is set to the communication position 11b, the second switching valve 13 is set to the blocking position 13C, and the pump 14 is driven by the motor 15, the hydraulic oil supplied from the pump 14 into the cylinder 2 presses the piston 4 leftward in fig. 1 with respect to the cylinder 2, so that the cylinder device C generates an extension direction thrust.

When the pressure in the rod-side chamber 5 and the piston-side chamber 6 exceeds the valve opening pressure of the variable relief valve 41, the variable relief valve 41 opens, and the hydraulic oil is discharged to the reservoir 7 through the adjustment passage P1, so that the pressure in the rod-side chamber 5 and the piston-side chamber 6 becomes equal to the valve opening pressure of the variable relief valve 41. In this way, the variable relief valve 41 adjusts the pressure of the hydraulic oil supplied from the pump 14 into the cylinder 2 by adjusting the valve opening pressure. Accordingly, the cylinder device C generates an expansion direction thrust force, the value of which is the difference between the piston-side chamber-side and rod-side chamber-side pressure receiving areas of the piston 4 multiplied by the valve opening pressure of the variable relief valve 41, and the thrust force can be adjusted by adjusting the valve opening pressure of the variable relief valve 41. In this state, even if the expansion and contraction unit 1 is forced to contract forcibly by an external force, the pressure in the rod side chamber 5 and the pressure in the piston side chamber 6 are controlled to be equal to the valve opening pressure of the variable pressure reducing valve 41, so that an expansion direction thrust is generated to suppress contraction.

In the process of generating the thrust force in the extension direction by the cylinder device C, the expansion unit 1 is contracted at a high speed by an external force, and when the pressure in the piston side chamber 6 is abnormally high, the second compression side pressure reducing valve 33 is opened, so that the hydraulic oil in the piston side chamber 6 moves to the rod side chamber 5, and the cylinder device C is protected.

In contrast, when the cylinder device C is caused to generate the contraction direction thrust force, the first switching valve 11 is adjusted to the shut-off position 11C, the second switching valve 13 is adjusted to the communication position 13b, the pump 14 is driven by the motor 15, and the hydraulic oil is supplied from the reservoir tank 7 to the rod side chamber 5. Further, a current equal to or higher than a predetermined value is applied to the solenoid Sol, the bypass passage switching valve 44 is closed, the bypass passage P2 is shut off, and the valve opening pressure of the variable relief valve 41 is adjusted in accordance with the thrust force that the cylinder device C needs to exert.

In this way, after the second on-off valve 13 is opened, the piston side chamber 6 and the reservoir tank 7 are placed in communication through the second passage 12, the first on-off valve 11 is closed, and the communication between the rod side chamber 5 and the piston side chamber 6 is cut off, so that the hydraulic oil discharged from the pump 14 is supplied only to the rod side chamber 5. Further, the bypass passage switching valve 44 is closed, so the compression-side damping passage 26 is shut off, but the piston-side chamber 6 communicates with the reservoir tank 7 through the second passage 12.

Therefore, when the first switching valve 11 is set to the off position 11C and the second switching valve 13 is set to the on position 13b and the pump 14 is driven by the motor 15, the hydraulic oil supplied from the pump 14 to the rod-side chamber 5 presses the piston 4 rightward in fig. 1 against the cylinder 2, so that the cylinder device C generates a contraction direction thrust. The cylinder device C generates a contraction direction thrust force, the value of which is equal to the value obtained by subtracting the product of the piston-side chamber-side pressure receiving area of the piston 4 and the pressure of the reservoir tank 7 from the product of the rod-side chamber-side pressure receiving area of the piston 4 multiplied by the valve opening pressure of the variable pressure reducing valve 41, and the thrust force can be adjusted by adjusting the valve opening pressure of the variable pressure reducing valve 41. In this state, even if the expansion and contraction unit 1 is forced to expand by an external force, the pressure in the rod side chamber 5 can be controlled to be equal to the valve opening pressure of the variable pressure reducing valve 41, and thus a contraction direction thrust force for suppressing the expansion and contraction is generated.

As described above, when the cylinder device C of the present embodiment is caused to generate the contraction direction thrust force, it is necessary to supply the hydraulic oil to the rod side chamber 5 in a state where the communication between the rod side chamber 5 and the piston side chamber 6 is cut off. Here, if the extension-side pressure reducing valve 25 is opened, the extension-side damping passage 24 of the shock absorber circuit D allows the hydraulic oil of the rod-side chamber 5 to the piston-side chamber 6 to flow. Therefore, when the cylinder device C of the present embodiment is caused to generate the contraction direction thrust force, the hydraulic oil escapes from the rod side chamber 5 to the piston side chamber 6 when the extension side pressure reducing valve 25 is opened, and therefore the efficiency is deteriorated, but the valve opening pressure of the extension side pressure reducing valve 25 is set to be equal to or higher than the difference between the pressure in the rod side chamber 5 and the pressure in the piston side chamber 6 when the expansion unit 1 generates the maximum thrust force to the contraction side by the actuator circuit a. The maximum thrust in the contraction direction of the cylinder device C in the actuator mode is generated when the variable relief valve 41 maximizes the valve opening pressure. Therefore, when the cylinder device C of the present embodiment is used as an actuator for generating a contraction direction thrust force, even if the opening pressure of the variable relief valve 41 is set to the maximum, the extension side relief valve 25 does not open, and the hydraulic oil is prevented from moving from the rod side chamber 5 to the piston side chamber 6 through the extension side damping passage 24. In this way, if the valve opening pressure of the expansion-side pressure reducing valve 25 is set to be equal to or greater than the difference between the pressure in the rod-side chamber 5 and the pressure in the piston-side chamber 6 when the expansion unit 1 generates the maximum thrust in the contraction side by the actuator circuit a, the thrust can be efficiently generated when the cylinder device C is used as the actuator to generate the thrust in the contraction direction, and the energy consumption is small. As described above, in the cylinder device C of the present embodiment, even if the variable pressure reducing valve 41 that controls the pressure in the rod side chamber 5 is set to the maximum valve opening pressure, the extension side pressure reducing valve 25 does not need to be opened, and therefore the valve opening pressure of the extension side pressure reducing valve 25 only needs to be higher than the maximum valve opening pressure of the variable pressure reducing valve 41. In this case, the opening pressure of the extension side pressure reducing valve 25 is not the maximum opening pressure in terms of the hardware of the variable pressure reducing valve 41, and may be higher than the maximum opening pressure selectable in terms of the control of the variable pressure reducing valve 41 in the actuator mode.

As described above, from the viewpoint of efficiency, the valve opening pressure of the expansion-side pressure reducing valve 25 may be set to be equal to or greater than the difference between the pressure in the rod-side chamber 5 and the pressure in the piston-side chamber 6 when the expansion unit 1 generates the maximum thrust in the contraction side by the actuator circuit a.

In the process that the cylinder device C generates the thrust in the contraction direction, the telescopic unit 1 is stretched at a high speed by an external force, and when the pressure in the rod side chamber 5 is abnormally high, the stretching side pressure reducing valve 25 is opened, so that the hydraulic oil in the rod side chamber 5 moves to the piston side chamber 6, and the cylinder device C is protected.

In this way, the cylinder device C can generate thrust in any direction of the expansion direction and the contraction direction within the adjustment range of the opening pressure of the variable relief valve 41 by opening and closing the first and second opening and closing valves 11 and 13 and adjusting the opening pressure of the variable relief valve 41. Accordingly, in the actuator mode, the cylinder device C is driven and the first switching valve 11, the second switching valve 13, and the variable pressure reducing valve 41 are controlled, whereby the cylinder device C can be used as an actuator to suppress vibration of the vehicle body S.

Next, a damper mode in which the cylinder device C is used as a damper by the damper circuit D will be described. When the cylinder device C is set to the damper mode, the first switching valve 11 is set to the off position 11C, the second switching valve 13 is set to the off position 13C, the motor 15 is not driven, and the pump 14 is stopped. Further, the solenoid Sol is de-energized, and in the non-energized state, the bypass passage switching valve 44 is opened, and the bypass passage P2 is opened.

In this state, the communication between the rod-side chamber 5 and the piston-side chamber 6 via the first passage 10 is cut off, and the communication between the piston-side chamber 6 and the reservoir 7 via the second passage 12 is cut off. Then, after the solenoid Sol is de-energized, the bypass passage switching valve 44 is opened, so that the piston side chamber 6 and the reservoir 7 communicate through the compression side damping passage 26. In this way, when the cylinder device C is used as the damper in the damper mode, the bypass passage switching valve 44 is opened and the compression-side damper passage 26 is opened.

When the expansion and contraction unit 1 is expanded by an external force in a state where the cylinder device C is set to the damper mode, the piston 4 moves leftward in fig. 1 with respect to the cylinder 2, and the rod side chamber 5 is contracted and the piston side chamber 6 is expanded. The hydraulic oil in the contracted rod-side chamber 5 passes through one or both of the relief valve 43 of the bypass passage P2 and the extension-side relief valve 25 of the extension-side damping passage 24, receives resistance of one or both of the relief valve 43 and the extension-side relief valve 25, and moves to the reservoir 7 or the enlarged piston-side chamber 6. When the expansion unit 1 performs the expansion operation, the rod 3 is withdrawn from the cylinder 2, so that the hydraulic oil in the cylinder 2 is insufficient, but after the suction check valve 29 is opened, the insufficient hydraulic oil is supplied from the reservoir 7 to the piston-side chamber 6 through the suction passage 28. When the cylinder device C enters the damper mode and the expansion unit 1 executes the expansion operation in this way, the pressure in the rod side chamber 5 increases due to the pressure reducing valve 43 and the expansion side pressure reducing valve 25, and the pressure in the piston side chamber 6 becomes equal to the tank pressure. Therefore, the cylinder device C generates a damping force in a direction that hinders the expansion and contraction unit 1, and the damping force is equal to a value obtained by multiplying the rod-side chamber-side pressure receiving area of the piston 4 by the pressure in the rod-side chamber 5 minus a product obtained by multiplying the piston-side chamber-side pressure receiving area of the piston 4 by the pressure in the reservoir tank 7.

When the expansion and contraction unit 1 is contracted by an external force while the cylinder device C is in the damper mode, the piston 4 moves rightward in fig. 1 with respect to the cylinder 2, and the piston-side chamber 6 is contracted and the rod-side chamber 5 is expanded. The hydraulic oil in the contracted piston-side chamber 6 moves to the expanded rod-side chamber 5 through the second compression-side pressure reducing valve 33 of the compression-side passage 32. When the expansion unit 1 performs the contraction operation, the rod 3 enters the cylinder 2, so that the hydraulic oil in the cylinder 2 is excessive, but after the first compression-side pressure reducing valve 27 is opened, the excessive part of the hydraulic oil is discharged from the piston-side chamber 6 to the reservoir tank 7 through the compression-side damping passage 26. As described above, when the cylinder device C enters the damper mode and the expansion and contraction unit 1 performs the expansion and contraction operation, the pressure in the piston side chamber 6 is increased by the first compression side pressure reducing valve 27 and the second compression side pressure reducing valve 33, the pressure in the rod side chamber 5 is reduced, and the pressure in the piston side chamber 6 becomes higher than the pressure in the rod side chamber 5. Therefore, the cylinder device C generates a damping force in a direction that prevents the expansion and contraction unit 1 from contracting, and the damping force is equal to a value obtained by multiplying the piston-side chamber-side pressure receiving area of the piston 4 by the pressure in the piston-side chamber 6 minus the product obtained by multiplying the rod-side chamber-side pressure receiving area of the piston 4 by the pressure in the rod-side chamber 5. In the cylinder device C of the present embodiment, since the damper circuit D includes the expansion-side intake passage 30 and the expansion-side check valve 31, when the expansion unit 1 of the damper mode cylinder device C is contracted, if the pressure in the rod-side chamber 5 is lower than the tank pressure, the expansion-side check valve 31 is opened, and the hydraulic oil is supplied from the tank 7 to the rod-side chamber 5. Therefore, when the cylinder device C of the present embodiment is contracted in the damper mode, no negative pressure is generated in the rod side chamber 5, and there is no risk of aeration and damping force hysteresis occurring during the switching of the expansion and contraction unit 1 from contraction to extension.

In this way, in the damper mode, when the expansion unit 1 is expanded or contracted by an external force, the cylinder device C generates a damping force that prevents the expansion unit 1 from expanding or contracting. The cylinder device C in the damper mode generates a damping force by one or both of the pressure reducing valve 43 and the expansion side pressure reducing valve 25 when the expansion unit 1 expands, and generates a damping force by the first compression side pressure reducing valve 27 and the second compression side pressure reducing valve 33 when the expansion unit 1 contracts. Accordingly, the damping force characteristics of the damping force generated by the piston speed when the expansion operation is performed with respect to the shock absorber mode cylinder device C are set by the pressure reducing valve 43 and the expansion side pressure reducing valve 25, and the damping force characteristics of the damping force generated by the piston speed when the contraction operation is performed with respect to the shock absorber mode cylinder device C are set by the first compression side pressure reducing valve 27 and the second compression side pressure reducing valve 33, so that the damping force characteristics when the expansion operation is performed and the contraction operation is performed can be set independently.

That is, the damping force characteristics of the cylinder device C of the present embodiment in the shock absorber mode can be independently adjusted by the settings of the pressure reducing valve 43, the extension side pressure reducing valve 25, the first compression side pressure reducing valve 27, and the second compression side pressure reducing valve 33, regardless of the settings of the rod side chamber side pressure receiving area and the piston side chamber side pressure receiving area of the piston 4. In other words, when the two damping force characteristics at the time of executing the extension operation and the time of executing the contraction operation of the cylinder device C of the present embodiment of the shock absorber mode are set to be the same, it is not necessary to set the cross-sectional area of the rod 3 to be one half of the cross-sectional area of the piston 4, and after the rod 3 diameter and the piston 4 diameter (cylinder 2 diameter) are arbitrarily determined within the allowable strength range, it is only necessary to adjust the two damping force characteristics to be the same by setting the pressure reducing valve 43, the extension side pressure reducing valve 25, the first compression side pressure reducing valve 27, and the second compression side pressure reducing valve 33.

In addition, the shock absorber circuit D of the present embodiment includes the expansion-side suction passage 30 and the expansion-side check valve 31, and allows the hydraulic oil from the reservoir tank 7 to the expanded rod-side chamber 5 to flow when the expansion unit 1 of the shock absorber mode cylinder device C performs the contraction operation, so that the compression-side passage 32 and the second compression-side pressure reducing valve 33 can be omitted. In this case, the two damping force characteristics at the time of executing the extension operation and at the time of executing the contraction operation of the cylinder device C of the present embodiment of the shock absorber mode may be adjusted to be the same by setting the pressure reducing valve 43, the extension side pressure reducing valve 25, and the first compression side pressure reducing valve 27.

However, when the compression-side passage 32 and the second compression-side pressure reducing valve 33 are provided, the following advantages are provided: when the expansion and contraction unit 1 of the damper mode cylinder device C performs the contraction operation, if the pressure in the piston side chamber 6 is abnormally high, the second compression side pressure reducing valve 33 is opened, so that the hydraulic oil in the piston side chamber 6 moves to the rod side chamber 5, and the cylinder device C can be protected.

Further, since the shock absorber circuit D of the present embodiment has the compression-side passage 32 and the second compression-side pressure reducing valve 33, when the expansion and contraction unit 1 of the shock absorber mode cylinder device C performs the contraction operation, if there is no concern that the hydraulic oil supplied from the piston-side chamber 6 to the rod-side chamber 5 through the compression-side passage 32 causes the rod-side chamber 5 to form a negative pressure, the extension-side suction passage 30 and the extension-side check valve 31 may be omitted.

Further, instead of the second compression-side pressure reducing valve 33, a check valve that does not exert too much resistance to the hydraulic oil passing therethrough is provided in the compression-side passage 32, and when the expansion and contraction unit 1 of the shock absorber mode cylinder device C performs the contraction action, the damping force can be generated by only the resistance of the first compression-side pressure reducing valve 27. In this case, the damping force characteristic of the damping force generated by the piston speed when the expansion operation is performed with respect to the shock absorber mode cylinder device C may be set by the expansion side pressure reducing valve 25, and the damping force characteristic of the damping force generated by the piston speed when the contraction operation is performed with respect to the shock absorber mode cylinder device C may be set by the first compression side pressure reducing valve 27. Therefore, the damping force characteristics when the shock absorber mode cylinder device C performs the extension operation and when the contraction operation can be set to the same characteristics regardless of the setting of the rod-side chamber-side pressure receiving area and the piston-side chamber-side pressure receiving area of the piston 4.

As described above, the cylinder device C of the present embodiment includes: a telescopic unit 1, wherein the telescopic unit 1 is provided with a cylinder 2, a rod 3 and a piston 4, the rod 3 is movably inserted into the cylinder 2, the piston 4 is movably inserted into the cylinder 2 and is connected with the rod 3, and the cylinder 2 is divided into a rod side chamber 5 and a piston side chamber 6; a liquid storage tank 7; an actuator circuit a having a pump 14, a control passage 40, a rod-side chamber 5 and a tank 7, and a thrust adjuster FT provided in the control passage 40, the actuator circuit a being capable of driving the expansion and contraction unit 1 to expand and contract, the pump 14 being capable of supplying hydraulic oil (liquid) from the tank 7 to the cylinder 2; an extension-side damping passage 24, the extension-side damping passage 24 communicating the rod-side chamber 5 with the piston-side chamber 6; an extension-side pressure reducing valve 25 provided on the extension-side damping passage 24, which exerts resistance to the flow of hydraulic oil (liquid) from the rod-side chamber 5 to the piston-side chamber 6; a compression-side damping passage 26, the compression-side damping passage 26 connecting the piston-side chamber 6 to the thrust adjustment portion FT; a first compression-side pressure reducing valve (compression-side pressure reducing valve) 27, the first compression-side pressure reducing valve (compression-side pressure reducing valve) 27 being provided on the compression-side damping passage 26, imparting resistance to the flow of hydraulic oil (liquid) from the piston-side chamber 6 to the reservoir 7; a suction passage 28, the suction passage 28 communicating the reservoir 7 with the piston-side chamber 6; a shock absorber circuit D including a suction check valve 29, the suction check valve 29 being provided on the suction passage 28, allowing hydraulic oil (liquid) of the reservoir tank 7 to the piston-side chamber 6 to flow.

The cylinder device C of the present embodiment thus constructed can supply hydraulic oil (liquid) from the pump 14 to the cylinder 2 by the actuator circuit a to serve as an actuator, and can stop the pump 14 from serving as a damper by the damper circuit D.

When the cylinder device C of the present embodiment is used as a shock absorber, the damping force can be generated by the expansion side pressure reducing valve 25 when the expansion unit 1 performs the expansion operation, and the damping force can be generated by the first compression side pressure reducing valve (compression side pressure reducing valve) 27 when the expansion unit 1 performs the contraction operation. Therefore, when the cylinder device C of the present embodiment is used as a shock absorber, the damping force characteristics when the extension operation is performed and the damping force characteristics when the contraction operation is performed can be set to the same characteristics by setting the extension-side pressure reducing valve 25 and the first compression-side pressure reducing valve (compression-side pressure reducing valve) 27, regardless of the setting of the rod 3 diameter and the piston 4 diameter (cylinder 2 diameter).

That is, in the cylinder device C of the present embodiment, even if the rod 3 diameter is reduced within the allowable strength range instead of the cylinder 2 diameter being increased, the damping force characteristics when the expansion operation is performed and the damping force characteristics when the contraction operation is performed can be set to be the same when the device is used as a shock absorber. In the cylinder device C of the present embodiment, since the pressure receiving area of the piston 4 can be increased and the column rigidity (column rigidity) of the hydraulic oil (liquid) in the expansion and contraction unit 1 can be increased by reducing the diameter of the rod 3 within the allowable range of strength instead of increasing the diameter of the cylinder 2, a high damping force with good responsiveness can be generated when the cylinder device C is used as a shock absorber by increasing the damping coefficient. Therefore, according to the cylinder device C of the present embodiment, the function as an actuator can be exhibited without increasing the diameter, and the damping coefficient can be increased when the cylinder device C is used as a shock absorber.

In the cylinder device C according to the first embodiment, the thrust adjuster FT includes: a tuning passage P1 and a bypass passage P2, the tuning passage P1 and the bypass passage P2 being provided in parallel in the middle of the control passage 40; a variable pressure reducing valve 41, the variable pressure reducing valve 41 being provided on the adjustment passage P1; a pressure reducing valve 43 and a bypass passage switching valve 44, which pressure reducing valve 43 and bypass passage switching valve 44 are provided in series in this order on the bypass passage P2 from the rod side chamber 5 side, the compression side damping passage 26 connects the piston side chamber 6 between the pressure reducing valve 43 and bypass passage switching valve 44 of the bypass passage P2, the variable pressure reducing valve 41 and bypass passage switching valve 44 are solenoid valves driven by the same solenoid Sol, the variable pressure reducing valve 41 is adjustable in valve opening pressure when the solenoid Sol is energized, the bypass passage switching valve 44 is closed when the solenoid Sol is energized, and is opened when the solenoid Sol is not energized, the bypass passage switching valve 44 is closed to shut off the bypass passage P2 when the actuator mode of the pump 14 is driven, and the bypass passage switching valve 44 is opened to open the bypass passage P2 when the damper mode of the pump 14 is stopped.

The cylinder device C of the present embodiment thus configured can supply hydraulic oil (liquid) from the pump 14 to the cylinder 2 by the actuator circuit a, shut off the compression-side damping passage 26 by the bypass passage switching valve 44 to serve as an actuator, and stop the pump 14 from opening the compression-side damping passage 26 by the bypass passage switching valve 44 to serve as a shock absorber by the shock absorber circuit D.

That is, in the cylinder device C of the present embodiment, even if the rod 3 diameter is reduced within the allowable strength range instead of the cylinder 2 diameter being increased, the damping force characteristics when the expansion operation is performed and the damping force characteristics when the contraction operation is performed can be set to be the same when the device is used as a shock absorber. In the cylinder device C of the present embodiment, since the pressure receiving area of the piston 4 can be increased and the column rigidity (column rigidity) of the hydraulic oil (liquid) in the expansion and contraction unit 1 can be increased by reducing the diameter of the rod 3 within the allowable range of strength instead of increasing the diameter of the cylinder 2, a high damping force with good responsiveness can be generated when the cylinder device C is used as a shock absorber by increasing the damping coefficient. Therefore, according to the cylinder device C of the present embodiment, the function as an actuator can be exhibited without increasing the diameter, and the damping coefficient can be increased when the cylinder device C is used as a shock absorber. In addition, as shown in the one-way flow damper, even if the sectional area of the rod 3 is set to be half of the sectional area of the piston 4, the pressure in the piston-side chamber 6 can be set higher than the pressure in the rod-side chamber 5 when the cylinder device C is contracted by providing the compression-side passage 32 and the second compression-side pressure reducing valve 33, and therefore the damping coefficient when the contraction operation is performed can be set higher than that of the conventional cylinder device. Therefore, if the compression-side passage 32 and the second compression-side pressure reducing valve 33 are provided, the degree of freedom in setting the sectional area of the rod 3 and the sectional area of the piston 4 increases.

In the cylinder device C of the present embodiment, when the motor 15 and the solenoid valves, that is, the valves 11,13,41,44 of the cylinder device C are not energized, the bypass passage switching valve 44 automatically communicates the compression-side damper passage 26, and the cylinder device C is switched to the shock absorber mode. Therefore, according to the cylinder device C of the present embodiment, the damper circuit D is automatically activated when the vehicle is collapsed, and the vehicle body S of the railway vehicle T is also prevented from vibrating when the vehicle is collapsed, while switching to the damper mode.

In the cylinder device C of the present embodiment, the damper circuit D includes: an elongated side suction passage 30, the elongated side suction passage 30 communicating the liquid reservoir 7 with the rod side chamber 5; an extension-side check valve 31, the extension-side check valve 31 being provided on the extension-side suction passage 30 to allow only the hydraulic oil (liquid) of the reservoir tank 7 to the rod-side chamber 5 to flow. According to the cylinder device C thus configured, when the expansion and contraction unit 1 performs the contraction operation, no negative pressure is generated in the rod side chamber 5, and there is no risk of aeration occurring and damping force hysteresis occurring during the switching of the expansion and contraction unit 1 from contraction to extension.

Further, in the cylinder device C of the present embodiment, the actuator circuit a has a variable relief valve 41 that can adjust the pressure of the hydraulic oil (liquid) supplied from the pump 14 into the cylinder 2 by adjusting the valve opening pressure, and the valve opening pressure of the extension-side relief valve 25 is higher than the maximum valve opening pressure selectable by the variable relief valve 41 in the actuator mode. In the cylinder device C thus configured, when used as an actuator, the hydraulic oil (liquid) supplied from the pump 14 into the cylinder 2 is not allowed to escape from the rod side chamber 5 to the piston side chamber 6, so that contraction side thrust can be efficiently generated, and energy consumption is reduced.

< second embodiment >

As shown in fig. 3, the cylinder device C1 of the second embodiment includes and is constituted by: a telescopic unit 1, a reservoir 7, an actuator circuit A1, and a damper circuit D1. In the present embodiment, the two cylinder devices C1 are installed in parallel between the body S of the railway vehicle T and the bogie B as in the cylinder device C to suppress the horizontal vibration of the body S, but only one cylinder device C1 may be installed between the body S and the bogie B to be used.

Next, each portion of the cylinder device C1 will be described. The expansion unit 1 of the cylinder device C1 has the same configuration as the expansion unit 1 of the cylinder device C.

The actuator circuit A1 is a circuit that includes a pump 14 to drive the expansion unit 1 to expand and contract, and the pump 14 is provided between the cylinder 2 and the reservoir 7 and can supply hydraulic oil from the reservoir 7 to the cylinder 2. After driving the pump 14, the actuator circuit a supplies hydraulic oil into the cylinder 2, selects one of the expansion direction and the contraction direction, and causes the expansion unit 1 to generate a thrust force in the selected direction, and the thrust force can be adjusted.

Specifically, as shown in fig. 3, the actuator circuit a includes: a pump 14, the pump 14 being provided between the cylinder 2 and the reservoir 7, for supplying hydraulic oil to the rod-side chamber 5; a motor 15, said motor 15 driving the pump 14; a control passage 40, the control passage 40 communicating the rod-side chamber 5 with the liquid reservoir 7; a thrust adjustment unit FT1, the thrust adjustment unit FT1 being provided in the control passage 40; a first passage 10, the first passage 10 communicating the rod-side chamber 5 with the piston-side chamber 6; a first on-off valve 11, the first on-off valve 11 being provided on the first passage 10; a second passage 12, the second passage 12 communicating the piston-side chamber 6 with the reservoir 7; a second switching valve 13, the second switching valve 13 being disposed on the second passage 12.

The actuator circuit A1 of the cylinder device C1 of the second embodiment is different from the actuator circuit a of the cylinder device C of the first embodiment only in the configuration of the thrust adjuster FT1, and the other portions have the same configuration.

In the cylinder device C1 of the second embodiment, the rod-side chamber 5 and the reservoir 7 are connected by the control passage 40, and the thrust adjuster FT1 is provided in the middle of the control passage 40. The thrust adjustment unit FT1 includes: a tuning passage P3, the tuning passage P3 being provided midway in the control passage 40; a pressure reducing valve 46, wherein the pressure reducing valve 46 is opened after the pressure of the rod side chamber 5 reaches the valve opening pressure; the variable pressure reducing valve 47 is configured such that the opening pressure of the variable pressure reducing valve 47 is adjusted by energization, and the pressure reducing valve 46 and the variable pressure reducing valve 47 are sequentially connected in series from the rod side chamber 5 side in the adjustment passage P3.

The pressure reducing valve 46 includes and is constituted of: a valve body 46a, the valve body 46a being disposed on the adjustment passage P3; a spring 46b, wherein the spring 46b applies force to the valve body 46a to cut off the adjusting passage P3; a pilot passage 46c for applying a pressure to the valve body 46a in the upstream side of the valve body 46a, that is, in the rod-side chamber 5, so as to urge the valve body against the spring 46b in the valve opening direction. The valve opening pressure of the relief valve 46 is set to a valve opening pressure specified in advance in accordance with the urging force of the spring 46b against the valve body 46 a.

The variable relief valve 47 includes and is constituted by: a valve body 47a, the valve body 47a being provided on the adjustment passage P3; a spring 47b, wherein the spring 47b biases the valve body 47a to cut off the adjustment passage P3; a pilot passage 47c for applying a pressure to the valve body 47a from a rod-side chamber 5, which is an upstream side of the valve body 47a, to the valve body 47a so as to urge the spring 47b in a valve opening direction; a solenoid 47d that generates a thrust force against the spring 47b when the solenoid 47d is energized. The variable relief valve 47 is a solenoid valve, and the valve opening pressure can be adjusted by adjusting the amount of current flowing through the solenoid 47 d.

When the pressure upstream of the variable relief valve 47 and downstream of the relief valve 46 acting on the adjustment passage P3 of the valve body 47a exceeds the relief pressure (valve opening pressure) of the variable relief valve 47, the pressure and the force of the solenoid 47d pushing the valve body 47a overcomes the urging force of the spring 47b on the valve body 47a, the valve body 47a retreats, and the variable relief valve 47 opens the adjustment passage P3.

Further, with the variable relief valve 47, if the amount of current supplied to the solenoid 47d is increased, the thrust generated by the solenoid 47d can be increased. Therefore, when the amount of current supplied to the solenoid 47d is adjusted to the maximum, the valve opening pressure of the variable relief valve 47 becomes the minimum, whereas when no current is supplied to the solenoid 47d at all, the valve opening pressure of the variable relief valve 47 becomes the maximum.

Next, the damper circuit D1 includes: an extension-side damping passage 24, the extension-side damping passage 24 communicating the rod-side chamber 5 with the piston-side chamber 6; an extension-side pressure reducing valve 25 provided on the extension-side damping passage 24, which exerts resistance to the flow of hydraulic oil from the rod-side chamber 5 to the piston-side chamber 6; a compression-side damping passage 26, the compression-side damping passage 26 being connected to the piston-side chamber 6 and to the thrust adjustment portion FT1; a first compression-side pressure reducing valve 27, the first compression-side pressure reducing valve 27 being provided as a compression-side pressure reducing valve on the compression-side damping passage 26, imparting resistance to the flow of hydraulic oil from the piston-side chamber 6 to the reservoir 7; a suction passage 28, the suction passage 28 communicating the reservoir 7 with the piston-side chamber 6; a suction check valve 29 provided on the suction passage 28, allowing the hydraulic oil of the reservoir tank 7 to the piston-side chamber 6 to flow; an elongated side suction passage 30, the elongated side suction passage 30 communicating the liquid reservoir 7 with the rod side chamber 5; an extension-side check valve 31 provided on the extension-side suction passage 30, allowing only the hydraulic oil of the reservoir tank 7 to the rod-side chamber 5 to flow; a compression-side passage 32, the compression-side passage 32 communicating the piston-side chamber 6 with the rod-side chamber 5; a second compression-side pressure reducing valve 33, the second compression-side pressure reducing valve 33 being provided on the compression-side passage 32, imparting resistance to the flow of hydraulic oil from the piston-side chamber 6 to the rod-side chamber 5.

The shock absorber circuit D1 of the cylinder device C1 according to the second embodiment is different from the shock absorber circuit D of the cylinder device C according to the first embodiment in that the compression-side damper passage 26 is connected to the pressure reducing valve 46 and the variable pressure reducing valve 47 of the adjustment passage P3 of the thrust adjustment portion FT1, and the other portions have the same configuration.

As described above, the compression-side damper passage 26 is connected to the thrust adjuster FT1, but unlike the cylinder device C of the first embodiment, the on-off valve is not provided in the adjustment passage P3 of the thrust adjuster FT1, so that the communication between the compression-side damper passage 26 and the reservoir tank 7 is not interrupted.

The cylinder device C1 is configured as described above, and the operation of the cylinder device C1 will be described below. First, an actuator mode in which the cylinder device C1 is used as an actuator by the actuator circuit A1 will be described. When the cylinder device C1 is caused to generate thrust in the extension direction, the first switching valve 11 is set to the communication position 11b, the second switching valve 13 is set to the cut-off position 13C, the pump 14 is driven by the motor 15, and the hydraulic oil is supplied from the reservoir 7 into the cylinder 2. The amount of current supplied to the solenoid 47d is adjusted, and the valve opening pressure of the variable relief valve 47 is adjusted according to the thrust force that the cylinder device C1 needs to exert.

In this way, after the first on-off valve 11 is opened, the rod-side chamber 5 and the piston-side chamber 6 are placed in communication through the first passage 10, and hydraulic oil is supplied from the pump 14 to the rod-side chamber 5 and the piston-side chamber 6.

Therefore, when the first switching valve 11 is set to the communication position 11b, the second switching valve 13 is set to the blocking position 13C, and the pump 14 is driven by the motor 15, the hydraulic oil supplied from the pump 14 into the cylinder 2 presses the piston 4 leftward in fig. 1 with respect to the cylinder 2, so that the cylinder device C1 generates an extension direction thrust.

In the cylinder device C1 of the second embodiment, the compression-side damping passage 26 is not shut off by the on-off valve. Therefore, the hydraulic oil supplied into the cylinder 2 can be moved from the rod-side chamber 5 to the reservoir tank 7 via the control passage 40 and the thrust adjuster FT1, and from the piston-side chamber 6 to the reservoir tank 7 via the compression-side damping passage 26, the first compression-side pressure reducing valve 27, and the thrust adjuster FT 1.

Moreover, both the pressure in the rod-side chamber 5 and the pressure in the piston-side chamber 6 that communicates with the rod-side chamber 5 via the first passage 10 exceed the valve opening pressures of the relief valve 46 and the first compression-side relief valve 27, and if the variable relief valve 47 is opened, the hydraulic oil in the rod-side chamber 5 moves to the reservoir tank 7 via the control passage 40 and the adjustment passage P3, and the hydraulic oil in the piston-side chamber 6 moves to the reservoir tank 7 via the compression-side damping passage 26 and the adjustment passage P3.

That is, when the first switching valve 11 is set to the communication position 11b and the second switching valve 13 is set to the blocking position 13c, the following circuit configuration is formed: a pressure reducing valve 46 and a first compression side pressure reducing valve 27 are arranged in parallel between the cylinder 2 and the reservoir 7, and a variable pressure reducing valve 47 is arranged downstream of these pressure reducing valves 46 and 27.

When the first switching valve 11 is set to the communication position 11b and the second switching valve 13 is set to the blocking position 13c, if hydraulic oil is supplied from the pump 14 into the cylinder 2 and the hydraulic oil in the cylinder 2 is excessive, the hydraulic oil pushed out from the cylinder 2 passes through one or both of the pressure reducing valve 46 and the first compression side pressure reducing valve 27 and then is necessarily moved to the reservoir 7 through the variable pressure reducing valve 47, so that the pressure in the cylinder 2 can be adjusted by adjusting the valve opening pressure of the variable pressure reducing valve 47. In this way, in the cylinder device C1 according to the second embodiment, when the first switching valve 11 is set to the communication position 11b and the second switching valve 13 is set to the blocking position 13C, the pressure reducing valve 46, the first compression-side pressure reducing valve 27, and the variable pressure reducing valve 47 form resistance, the pressure in the cylinder 2 increases, and the cylinder device C1 generates thrust in the extension direction.

As described above, in the cylinder device C1 according to the second embodiment, when the first switching valve 11 is adjusted to the communication position 11b and the second switching valve 13 is adjusted to the blocking position 13C, the thrust in the extension direction is generated as in the cylinder device C, and the thrust is adjusted by multiplying the difference between the piston-side chamber-side and rod-side chamber-side pressure receiving areas of the piston 4 by the rod-side chamber 5 pressure, and by adjusting the opening pressure of the variable relief valve 47. In this state, even if the expansion and contraction unit 1 is forced to contract forcibly by an external force, the pressures in the rod side chamber 5 and the piston side chamber 6 can be controlled by the variable pressure reducing valve 47, and an expansion direction thrust force suppressing contraction can be generated.

In addition, in the process of generating the thrust force in the extension direction by the cylinder device C1, the expansion unit 1 is contracted at a high speed by the external force, and when the pressure in the piston side chamber 6 is abnormally high, the second compression side pressure reducing valve 33 is opened, so that the hydraulic oil in the piston side chamber 6 moves to the rod side chamber 5, and the cylinder device C1 is protected.

In contrast, when the cylinder device C1 is caused to generate the contraction direction thrust force, the first switching valve 11 is adjusted to the shut-off position 11C, the second switching valve 13 is adjusted to the communication position 13b, the pump 14 is driven by the motor 15, and the hydraulic oil is supplied from the reservoir tank 7 to the rod side chamber 5. The amount of current supplied to the solenoid 47d is adjusted, and the valve opening pressure of the variable relief valve 47 is adjusted according to the thrust force that the cylinder device C1 needs to exert.

In this way, after the second on-off valve 13 is opened, the piston side chamber 6 and the reservoir tank 7 are placed in communication through the second passage 12, the first on-off valve 11 is closed, and the communication between the rod side chamber 5 and the piston side chamber 6 is cut off, so that the hydraulic oil discharged from the pump 14 is supplied only to the rod side chamber 5. In the cylinder device C1, the compression-side damper passage 26 is not shut off by the on-off valve, but when the cylinder device C1 contracts in a state in which the piston-side chamber 6 and the reservoir tank 7 are communicated with each other through the second passage 12, the hydraulic oil moves from the piston-side chamber 6 to the reservoir tank 7 only through the second passage 12.

Therefore, when the first switching valve 11 is set to the off position 11C and the second switching valve 13 is set to the on position 13b and the pump 14 is driven by the motor 15, the hydraulic oil supplied from the pump 14 to the rod-side chamber 5 presses the piston 4 rightward in fig. 1 against the cylinder 2, so that the cylinder device C1 generates a contraction direction thrust.

In the cylinder device C1 of the second embodiment, when the first on-off valve 11 is set to the off position 11C, the second on-off valve 13 is set to the on position 13b, and the pump 14 is driven by the motor 15, only the hydraulic oil is supplied to the rod side chamber 5. If the hydraulic oil in the rod-side chamber 5 is excessive, the hydraulic oil pushed out from the rod-side chamber 5 moves to the reservoir 7 through the pressure reducing valve 46 and the variable pressure reducing valve 47, so that the pressure in the cylinder 2 can be adjusted by adjusting the valve opening pressure of the variable pressure reducing valve 47. Therefore, in the cylinder device C1 of the second embodiment, when the first switching valve 11 is set to the off position 11C and the second switching valve 13 is set to the communication position 13b, the pressure reducing valve 46 and the variable pressure reducing valve 47 form resistance, the pressure in the cylinder 2 increases, and the cylinder device C1 generates contraction direction thrust.

As described above, in the cylinder device C1 according to the second embodiment, when the first switching valve 11 is set to the shut-off position 11C and the second switching valve 13 is set to the communication position 13b, similarly to the cylinder device C, the contraction direction thrust force is generated, the value of which is equal to the value obtained by subtracting the product of the piston-side chamber-side pressure receiving area of the piston 4 multiplied by the valve opening pressure of the variable relief valve 47 from the product of the piston-side chamber-side pressure receiving area of the piston 4 multiplied by the pressure of the reservoir tank 7, and the thrust force can be adjusted by adjusting the valve opening pressure of the variable relief valve 47. In this state, even if the expansion and contraction unit 1 is forced to expand by an external force, the pressure in the rod side chamber 5 is controlled by the variable pressure reducing valve 47, so that a contraction direction thrust force that suppresses the expansion and contraction is generated.

As described above, when the cylinder device C1 of the present embodiment is caused to generate the contraction direction thrust force, it is necessary to supply the hydraulic oil to the rod side chamber 5 in a state where the communication between the rod side chamber 5 and the piston side chamber 6 is cut off. Here, if the extension-side pressure reducing valve 25 is opened, the extension-side damping passage 24 of the shock absorber circuit D1 allows the hydraulic oil of the rod-side chamber 5 to the piston-side chamber 6 to flow.

Therefore, when the cylinder device C1 of the present embodiment is caused to generate the contraction direction thrust force, the hydraulic oil escapes from the rod side chamber 5 to the piston side chamber 6 when the extension side pressure reducing valve 25 is opened, and therefore the efficiency is deteriorated, but the valve opening pressure of the extension side pressure reducing valve 25 is set to be equal to or higher than the difference between the pressure in the rod side chamber 5 and the pressure in the piston side chamber 6 when the expansion unit 1 generates the maximum thrust force to the contraction side by the actuator circuit A1. The maximum thrust in the contraction direction of the cylinder device C1 in the actuator mode is generated when the variable relief valve 47 maximizes the valve opening pressure. Therefore, when the cylinder device C1 of the present embodiment is used as an actuator for generating a contraction direction thrust force, the extension side pressure reducing valve 25 does not open even when the opening pressure of the variable pressure reducing valve 47 is maximized, and the hydraulic oil is prevented from moving from the rod side chamber 5 to the piston side chamber 6 through the extension side damping passage 24. In this way, if the valve opening pressure of the expansion-side pressure reducing valve 25 is set to be equal to or greater than the difference between the pressure in the rod-side chamber 5 and the pressure in the piston-side chamber 6 when the expansion unit 1 generates the maximum thrust in the contraction side by the actuator circuit A1, the thrust can be efficiently generated when the cylinder device C1 is used as an actuator to generate the thrust in the contraction direction, and the energy consumption is small. As described above, in the cylinder device C1 of the present embodiment, even if the variable relief valve 47 that controls the pressure in the rod side chamber 5 is set to the maximum valve opening pressure, the valve opening pressure of the extension side relief valve 25 only needs to be higher than the pressure loss generated by the relief valve 46 and the variable relief valve 47 when the variable relief valve 47 is set to the maximum valve opening pressure, that is, the pressure loss generated by the thrust adjuster FT1, as long as the extension side relief valve 25 is not opened. In this case, the opening pressure of the extension-side pressure reducing valve 25 may be higher than the maximum pressure loss in terms of the hardware of the thrust adjuster FT1, which may be selectable in terms of the control of the thrust adjuster FT1 in the actuator mode.

As described above, from the viewpoint of efficiency, the valve opening pressure of the expansion-side pressure reducing valve 25 may be set to be equal to or greater than the difference between the pressure in the rod-side chamber 5 and the pressure in the piston-side chamber 6 when the expansion unit 1 generates the maximum thrust in the contraction side by the actuator circuit A1, but the cylinder device C1 may be used as an actuator to generate thrust in the contraction direction even if the valve opening pressure is set to be smaller than the difference.

In the process of generating the thrust force in the contraction direction by the cylinder device C1, the expansion unit 1 is expanded at a high speed by an external force, and when the pressure in the rod-side chamber 5 is abnormally high, the expansion-side pressure reducing valve 25 is opened, so that the hydraulic oil in the rod-side chamber 5 moves to the piston-side chamber 6, and the cylinder device C1 is protected.

In this way, the cylinder device C1 can generate thrust in any direction of the expansion direction and the contraction direction within the adjustable range by opening and closing the first and second opening and closing valves 11 and 13 and adjusting the opening pressure of the variable pressure reducing valve 47. Accordingly, in the actuator mode, the cylinder device C1 drives the pump 14 and controls the first switching valve 11, the second switching valve 13, and the variable relief valve 47, whereby the cylinder device C1 can be used as an actuator to suppress vibration of the vehicle body S.

Next, a damper mode in which the cylinder device C is used as a damper by the damper circuit D1 will be described. When the cylinder device C1 is set to the damper mode, the first switching valve 11 is set to the off position 11C, the second switching valve 13 is set to the off position 13C, the motor 15 is not driven, and the pump 14 is stopped. The solenoid 47d may be energized or may be de-energized.

In this state, the communication between the rod-side chamber 5 and the piston-side chamber 6 via the first passage 10 is cut off, and the communication between the piston-side chamber 6 and the reservoir 7 via the second passage 12 is cut off. In this way, when the cylinder device C1 is used as a shock absorber in the shock absorber mode, the compression-side damping passage 26 also communicates with the reservoir tank 7 via the variable relief valve 47 of the thrust adjustment portion FT 1.

When the expansion and contraction unit 1 is expanded by an external force in a state where the cylinder device C1 is set to the damper mode, the piston 4 moves leftward in fig. 1 with respect to the cylinder 2, and the rod side chamber 5 is contracted and the piston side chamber 6 is expanded. The hydraulic oil in the contracted rod-side chamber 5 is subjected to resistance by one or both of the thrust adjuster FT1 and the extension-side pressure reducing valve 25 of the extension-side damping passage 24 by one or both of the thrust adjuster FT1 and the extension-side pressure reducing valve 25, and moves to the reservoir 7 or the enlarged piston-side chamber 6. When the expansion unit 1 performs the expansion operation, the rod 3 is withdrawn from the cylinder 2, so that the hydraulic oil in the cylinder 2 is insufficient, but after the suction check valve 29 is opened, the insufficient hydraulic oil is supplied from the reservoir 7 to the piston-side chamber 6 through the suction passage 28. As described above, when the cylinder device C1 enters the damper mode and the expansion unit 1 executes the expansion operation, the pressure in the rod side chamber 5 increases due to the thrust adjustment portion FT1 and the expansion side pressure reducing valve 25, and the pressure in the piston side chamber 6 becomes equal to the tank pressure. Therefore, the cylinder device C1 generates a damping force in a direction that hinders the expansion and contraction unit 1, and the damping force is equal to a value obtained by multiplying the rod-side chamber-side pressure receiving area of the piston 4 by the pressure in the rod-side chamber 5 minus a product obtained by multiplying the piston-side chamber-side pressure receiving area of the piston 4 by the pressure in the reservoir tank 7.

When the expansion and contraction unit 1 is contracted by an external force while the cylinder device C1 is in the damper mode, the piston 4 moves rightward in fig. 1 with respect to the cylinder 2, and the piston-side chamber 6 is contracted and the rod-side chamber 5 is expanded. The hydraulic oil in the contracted piston-side chamber 6 moves to the expanded rod-side chamber 5 through the second compression-side pressure reducing valve 33 of the compression-side passage 32. When the expansion/contraction unit 1 performs the contraction operation, the rod 3 enters the cylinder 2, and thus the hydraulic oil in the cylinder 2 is excessive, but after the first compression-side pressure reducing valve 27 and the variable pressure reducing valve 47 are opened, the excessive part of the hydraulic oil is discharged from the piston-side chamber 6 to the reservoir 7 through the compression-side damper passage 26, the adjustment passage P3, and the control passage 40. As described above, when the cylinder device C1 enters the damper mode and the expansion and contraction unit 1 executes the expansion and contraction operation, the pressure in the piston-side chamber 6 increases due to the first compression-side pressure reducing valve 27, the variable pressure reducing valve 47, and the second compression-side pressure reducing valve 33, the pressure in the rod-side chamber 5 is reduced, and the pressure in the piston-side chamber 6 becomes higher than the pressure in the rod-side chamber 5. Therefore, the cylinder device C1 generates a damping force in a direction that prevents the expansion and contraction unit 1 from contracting, and the damping force is equal to a value obtained by multiplying the piston-side chamber-side pressure receiving area of the piston 4 by the pressure in the piston-side chamber 6 minus the product obtained by multiplying the rod-side chamber-side pressure receiving area of the piston 4 by the pressure in the rod-side chamber 5. In the cylinder device C1 of the present embodiment, since the damper circuit D1 includes the expansion-side suction passage 30 and the expansion-side check valve 31, when the expansion unit 1 of the damper mode cylinder device C1 is contracted, if the pressure in the rod-side chamber 5 is lower than the tank pressure, the expansion-side check valve 31 is opened, and the hydraulic oil is supplied from the tank 7 to the rod-side chamber 5. Therefore, when the cylinder device C1 of the present embodiment is contracted in the damper mode, no negative pressure is generated in the rod side chamber 5, and no aeration occurs, and no damping force hysteresis occurs in the process of switching the expansion and contraction unit 1 from contraction to extension.

In this way, in the damper mode, when the expansion unit 1 is expanded or contracted by an external force, the cylinder device C1 generates a damping force that prevents the expansion unit 1 from expanding or contracting. The cylinder device C1 in the damper mode generates a damping force by one or both of the thrust adjuster FT1 and the expansion-side pressure reducing valve 25 when the expansion unit 1 expands, and generates a damping force by the first compression-side pressure reducing valve 27, the variable pressure reducing valve 47, and the second compression-side pressure reducing valve 33 when the expansion unit 1 contracts. Accordingly, the damping force characteristics of the damping force generated by the piston speed when the expansion operation is performed with respect to the shock absorber mode cylinder device C1 are set by the relief valve 46, the variable relief valve 47, and the expansion side relief valve 25 of the thrust adjustment unit FT1, and the damping force characteristics of the damping force generated by the piston speed when the contraction operation is performed with respect to the shock absorber mode cylinder device C1 are set by the first compression side relief valve 27, the variable relief valve 47, and the second compression side relief valve 33, so that the damping force characteristics when the expansion operation is performed and the contraction operation is performed can be set independently.

That is, the damping force characteristics of the cylinder device C of the present embodiment in the shock absorber mode can be independently adjusted by the settings of the pressure reducing valve 46, the variable pressure reducing valve 47, the extension side pressure reducing valve 25, the first compression side pressure reducing valve 27, and the second compression side pressure reducing valve 33, regardless of the settings of the rod side chamber side pressure receiving area and the piston side chamber side pressure receiving area of the piston 4. In other words, when the two damping force characteristics at the time of executing the extension operation and the time of executing the contraction operation of the cylinder device C1 of the present embodiment of the shock absorber mode are set to be the same, it is not necessary to set the cross-sectional area of the rod 3 to be one half of the cross-sectional area of the piston 4, and after the rod 3 diameter and the piston 4 diameter (cylinder 2 diameter) are arbitrarily determined within the allowable strength range, it is only necessary to adjust the two damping force characteristics to be the same by setting the pressure reducing valve 46, the variable pressure reducing valve 47, the extension side pressure reducing valve 25, the first compression side pressure reducing valve 27, and the second compression side pressure reducing valve 33.

In addition, the shock absorber circuit D1 of the present embodiment includes the expansion-side suction passage 30 and the expansion-side check valve 31, and allows the hydraulic oil from the reservoir tank 7 to the expanded rod-side chamber 5 to flow when the expansion unit 1 of the shock absorber mode cylinder device C1 performs the contraction operation, so that the compression-side passage 32 and the second compression-side pressure reducing valve 33 can be omitted. In this case, the two damping force characteristics at the time of executing the expansion operation and at the time of executing the contraction operation of the cylinder device C1 of the present embodiment of the shock absorber mode may be adjusted to be identical by setting the pressure reducing valve 46, the variable pressure reducing valve 47, the expansion side pressure reducing valve 25, and the first compression side pressure reducing valve 27.

However, when the compression-side passage 32 and the second compression-side pressure reducing valve 33 are provided, the following advantages are provided: when the expansion and contraction unit 1 of the damper mode cylinder device C1 performs the expansion and contraction operation, if the pressure in the piston side chamber 6 is abnormally high, the second compression side pressure reducing valve 33 is opened, so that the hydraulic oil in the piston side chamber 6 moves to the rod side chamber 5, and the cylinder device C1 can be protected.

Further, since the shock absorber circuit D1 of the present embodiment includes the compression-side passage 32 and the second compression-side pressure reducing valve 33, when the expansion and contraction unit 1 of the shock absorber mode cylinder device C1 performs the contraction operation, if there is no concern that the hydraulic oil supplied from the piston-side chamber 6 to the rod-side chamber 5 through the compression-side passage 32 causes the rod-side chamber 5 to form a negative pressure, the extension-side suction passage 30 and the extension-side check valve 31 may be omitted.

Further, the compression-side passage 32 is provided with a check valve that does not exert too much resistance against the hydraulic oil passing therethrough, instead of the second compression-side pressure reducing valve 33, and when the expansion and contraction unit 1 of the shock absorber mode cylinder device C1 performs the contraction operation, the damping force can be generated by the resistance of the first compression-side pressure reducing valve 27 and the variable pressure reducing valve 47. In this case, the damping force characteristics of the damping force generated by the piston speed when the expansion operation is performed with respect to the shock absorber mode cylinder device C1 may be set by the expansion side pressure reducing valve 25, the pressure reducing valve 46, and the variable pressure reducing valve 47, and the damping force characteristics of the damping force generated by the piston speed when the contraction operation is performed with respect to the shock absorber mode cylinder device C may be set by the first compression side pressure reducing valve 27 and the variable pressure reducing valve 47. Therefore, the damping force characteristics when the shock absorber mode cylinder device C1 performs the extension operation and when the contraction operation can be set to the same characteristics regardless of the setting of the rod-side chamber-side pressure receiving area and the piston-side chamber-side pressure receiving area of the piston 4.

As described above, the cylinder device C1 of the present embodiment includes: a telescopic unit 1, wherein the telescopic unit 1 is provided with a cylinder 2, a rod 3 and a piston 4, the rod 3 is movably inserted into the cylinder 2, the piston 4 is movably inserted into the cylinder 2 and is connected with the rod 3, and the cylinder 2 is divided into a rod side chamber 5 and a piston side chamber 6; a liquid storage tank 7; an actuator circuit A1, wherein the actuator circuit A1 has a pump 14, a control passage 40, and a thrust adjuster FT1, and the telescopic unit 1 is driven to be telescopic, the pump 14 can supply hydraulic oil (liquid) from the tank 7 to the cylinder 2, the control passage 40 communicates the rod side chamber 5 with the tank 7, and the thrust adjuster FT1 is provided in the control passage 40; an extension-side damping passage 24, the extension-side damping passage 24 communicating the rod-side chamber 5 with the piston-side chamber 6; an extension-side pressure reducing valve 25 provided on the extension-side damping passage 24, which exerts resistance to the flow of hydraulic oil (liquid) from the rod-side chamber 5 to the piston-side chamber 6; a compression-side damping passage 26, the compression-side damping passage 26 connecting the piston-side chamber 6 to the thrust adjustment portion FT1; a first compression-side pressure reducing valve (compression-side pressure reducing valve) 27, the first compression-side pressure reducing valve (compression-side pressure reducing valve) 27 being provided on the compression-side damping passage 26, imparting resistance to the flow of hydraulic oil (liquid) from the piston-side chamber 6 to the reservoir 7; a suction passage 28, the suction passage 28 communicating the reservoir 7 with the piston-side chamber 6; a shock absorber circuit D1, the shock absorber circuit D1 including a suction check valve 29, the suction check valve 29 being provided on a suction passage 28, allowing hydraulic oil (liquid) of the reservoir tank 7 to the piston-side chamber 6 to flow.

The cylinder device C1 of the present embodiment thus configured can supply hydraulic oil (liquid) from the pump 14 to the cylinder 2 by the actuator circuit A1 to serve as an actuator, and can stop the pump 14 from serving as a damper by the damper circuit D1.

When the cylinder device C1 of the present embodiment is used as a shock absorber, the damping force can be generated by the expansion side pressure reducing valve 25 when the expansion unit 1 performs the expansion operation, and the damping force can be generated by the first compression side pressure reducing valve (compression side pressure reducing valve) 27 when the expansion unit 1 performs the contraction operation. Therefore, when the cylinder device C1 of the present embodiment is used as a shock absorber, the damping force characteristic when the extension operation is performed and the damping force characteristic when the contraction operation is performed can be set to the same characteristic by setting the extension-side pressure reducing valve 25 and the first compression-side pressure reducing valve (compression-side pressure reducing valve) 27 regardless of the setting of the rod 3 diameter and the piston 4 diameter (cylinder 2 diameter).

That is, in the cylinder device C1 of the present embodiment, even if the rod 3 diameter is reduced within the allowable strength range instead of the cylinder 2 diameter being increased, the damping force characteristics when the expansion operation is performed and the damping force characteristics when the contraction operation is performed can be set to be the same when the device is used as a shock absorber. In the cylinder device C1 of the present embodiment, since the pressure receiving area of the piston 4 can be increased and the column rigidity (column rigidity) of the hydraulic oil (liquid) in the expansion and contraction unit 1 can be increased by reducing the diameter of the rod 3 within the allowable strength range instead of increasing the diameter of the cylinder 2, a high damping force with good responsiveness can be generated when the cylinder device C1 is used as a shock absorber. Therefore, according to the cylinder device C1 of the present embodiment, the function as an actuator can be exhibited without increasing the diameter, and the damping coefficient can be improved when the cylinder device is used as a shock absorber.

In the cylinder device C of the first embodiment, the compression-side damping passage 26 provided with the first compression-side pressure reducing valve 27 is connected between the pressure reducing valve 43 of the bypass passage P2 provided with the bypass passage switching valve 44 and the bypass passage switching valve 44, and the bypass passage switching valve 44 is cut off in the actuator mode, so that the compression-side damping passage 26 is cut off without the switching valve in the actuator mode, but in the cylinder device C1 of the second embodiment, the compression-side damping passage 26 is connected to the upstream of the variable pressure reducing valve 47 of the thrust adjusting portion FT1, and the first compression-side pressure reducing valve 27 is used to generate the thrust of the actuator mode cylinder device C1. On the other hand, the cylinder device C of the first embodiment and the cylinder device C1 of the second embodiment certainly generate damping force by the first compression-side pressure reducing valve 27 in the shock absorber mode. In this way, the thrust adjuster FT, FT1 may be configured to generate the damping force by the first compression-side pressure reducing valve 27 in the shock absorber mode, and in the actuator mode, the compression-side damping passage 26 provided with the first compression-side pressure reducing valve 27 may be completely shut off as in the cylinder device C of the first embodiment, or the communication state may be maintained without shutting off the compression-side damping passage 26 as in the cylinder device C1 of the second embodiment.

That is, as shown in the thrust adjustment portion FT1 of the second embodiment, when only one adjustment passage P3 having the variable relief valve 47 that can adjust the thrust force is provided, the compression-side damper passage 26 may be connected upstream of the variable relief valve 47. As shown in the thrust adjuster FT of the first embodiment, when the adjustment passage P1 having the variable pressure reducing valve 41 for adjusting the thrust and the bypass passage P2 having the bypass passage switching valve 44 that is opened in the damper mode are provided, the compression-side damper passage 26 may be connected to the upstream side of the bypass passage switching valve 44 of the bypass passage P2 that is activated in the damper mode. Further, the thrust adjuster FT, FT1 may have three or more parallel passages, and the compression-side damper passage 26 may be connected to the variable relief valve or the on-off valve upstream of the passage in which the variable relief valve or the on-off valve is provided. As described above, the thrust adjuster FT, FT1 may control the pressure in the cylinder 2 upstream in the actuator mode, that is, may adjust the thrust of the cylinder devices C, C1, and may include a passage in which a variable relief valve or a switching valve is provided and which is in a communication state in the damper mode, and the compression-side damper passage 26 may be connected to the upstream of the variable relief valve or the switching valve of the passage in the communication state in the damper mode.

In the cylinder device C1 according to the second embodiment, the thrust adjuster FT1 includes: a tuning passage P3, the tuning passage P3 being provided midway in the control passage 40; a pressure reducing valve 46, wherein the pressure reducing valve 46 is opened after the pressure of the rod side chamber 5 reaches the valve opening pressure; the variable pressure reducing valve 46 is configured such that the pressure of the opening valve is adjusted by energization, the pressure reducing valve 46 and the variable pressure reducing valve 47 are sequentially arranged in series from the rod side chamber 5 side in the adjustment passage P3, and the compression side damping passage 26 connects the piston side chamber 6 between the pressure reducing valve 46 and the variable pressure reducing valve 47 in the adjustment passage P3.

In the cylinder device C1 of the present embodiment thus configured, even if the thrust adjustment unit FT1 does not have the on-off valve for shutting off the compression-side damping passage 26 in the actuator mode, the compression-side damping force can be generated by the first compression-side pressure reducing valve 27 in the shock absorber mode, and the configuration of the thrust adjustment unit FT1 becomes simple, and the on-off valve is not required, so that the manufacturing cost of the cylinder device C1 can be reduced.

That is, in the cylinder device C1 of the present embodiment, even if the rod 3 diameter is reduced within the allowable strength range instead of the cylinder 2 diameter being increased, the damping force characteristics when the expansion operation is performed and the damping force characteristics when the contraction operation is performed can be set to be the same when the device is used as a shock absorber. In the cylinder device C of the present embodiment, since the pressure receiving area of the piston 4 can be increased and the column rigidity (column rigidity) of the hydraulic oil (liquid) in the expansion and contraction unit 1 can be increased by reducing the diameter of the rod 3 within the allowable range of strength instead of increasing the diameter of the cylinder 2, a high damping force with good responsiveness can be generated when the cylinder device C is used as a shock absorber by increasing the damping coefficient. Therefore, according to the cylinder device C1 of the present embodiment, the function as an actuator can be exhibited without increasing the diameter, and the damping coefficient can be improved when the cylinder device is used as a shock absorber. In addition, as shown in the one-way flow damper, even if the sectional area of the rod 3 is set to be half of the sectional area of the piston 4, the pressure in the piston-side chamber 6 can be set higher than the pressure in the rod-side chamber 5 when the cylinder device C1 is contracted by providing the compression-side passage 32 and the second compression-side pressure reducing valve 33, and therefore the damping coefficient when the contraction operation is performed can be set higher than that of the conventional cylinder device. Therefore, if the compression-side passage 32 and the second compression-side pressure reducing valve 33 are provided, the degree of freedom in setting the sectional area of the rod 3 and the sectional area of the piston 4 increases.

In the cylinder device C of the present embodiment, when the motor 15 and the solenoid valves, that is, the valves 11,13,47 of the cylinder device C are not energized, the cylinder device C1 is automatically switched to the damper mode. Therefore, according to the cylinder device C1 of the present embodiment, the damper circuit D1 is automatically activated when the vehicle is collapsed, and the vehicle body S of the railway vehicle T is also prevented from vibrating when the vehicle is collapsed, while switching to the damper mode.

In the cylinder device C1 of the present embodiment, the damper circuit D1 includes: an elongated side suction passage 30, the elongated side suction passage 30 communicating the liquid reservoir 7 with the rod side chamber 5; an extension-side check valve 31, the extension-side check valve 31 being provided on the extension-side suction passage 30 to allow only the hydraulic oil (liquid) of the reservoir tank 7 to the rod-side chamber 5 to flow. According to the cylinder device C1 thus configured, when the expansion and contraction unit 1 performs the contraction operation, no negative pressure is generated in the rod side chamber 5, and there is no risk of aeration occurring and damping force hysteresis occurring during the switching of the expansion and contraction unit 1 from the contraction to the expansion.

Further, in the cylinder device C1 of the present embodiment, the actuator circuit A1 has a variable relief valve 47 that can adjust the pressure in the cylinder 2 by adjusting the valve opening pressure, and the valve opening pressure of the extension-side relief valve 25 is higher than the maximum pressure loss selectable by the thrust adjuster FT1 in the actuator mode. In the cylinder device C1 thus configured, when used as an actuator, the hydraulic oil (liquid) supplied from the pump 14 into the cylinder 2 is not allowed to escape from the rod side chamber 5 to the piston side chamber 6, so that contraction side thrust can be efficiently generated, and energy consumption is reduced.

As described above, the description of the embodiments of the present invention is completed, but the scope of the present invention is not limited to the content shown in the drawings or the detailed description.

Symbol description

1. Telescopic unit

2. Cylinder

3. Rod piece

4. Piston

5. Rod piece side chamber

6. Piston side chamber

7. Liquid storage tank

14. Pump with a pump body

24. Elongated side damping channel

25. Extension side pressure reducing valve

26. Compression side damping channel

27. First compression side pressure reducing valve (compression side pressure reducing valve)

28. Suction channel

29. Suction check valve

30. Elongated side suction channel

31. Extension side check valve

40. Control channel

41,47 variable pressure reducing valve

42. Bypass channel

43,46 pressure reducing valve

44. Bypass channel switching valve

A, A1 actuator circuit

C, C1 cylinder device

D, D1 shock absorber circuit

FT, FT1 thrust adjustment portion

P1, P3 modulation channel

P2 bypass channel

Sol solenoid

Claims

1. A cylinder device is provided with:

the telescopic unit is provided with a cylinder, a rod and a piston, wherein the rod is movably inserted into the cylinder, and the piston is movably inserted into the cylinder and is connected with the rod to divide the cylinder into a rod side chamber and a piston side chamber;

A liquid storage tank;

an actuator circuit having a pump that can supply liquid from the tank to the cylinder, an adjustment passage that communicates the rod-side chamber with the tank and is provided with a variable pressure-reducing valve in the middle, and a bypass passage that communicates the rod-side chamber with the tank and is provided with a pressure-reducing valve and a bypass passage switching valve in the middle in series, and that can drive the expansion unit to expand and contract; and

a shock absorber circuit including an extension side damping passage that communicates the rod side chamber with the piston side chamber, an extension side pressure reducing valve provided on the extension side damping passage that applies resistance to liquid flow from the rod side chamber to the piston side chamber, a compression side damping passage that connects the piston side chamber to between the pressure reducing valve of the bypass passage and the bypass passage switching valve, a compression side pressure reducing valve provided on the compression side damping passage that applies resistance to liquid flow from the piston side chamber to the liquid reservoir, a suction passage that communicates the liquid reservoir with the piston side chamber, a suction check valve provided on the suction passage that allows liquid flow from the liquid reservoir to the piston side chamber,

The variable relief valve and the bypass passage switching valve are solenoid valves driven by the same solenoid,

the variable relief valve may adjust a valve opening pressure when the solenoid is energized,

the bypass passage switching valve is closed when the solenoid is energized, and is opened when the solenoid is not energized,

the bypass passage switching valve is closed to shut off the bypass passage when the actuator mode of the pump is driven,

the bypass passage switching valve is opened to open the bypass passage when the shock absorber mode of the pump is stopped.

2. A cylinder device is provided with:

a liquid storage tank;

an actuator circuit having a pump that can supply liquid from the liquid tank to the cylinder, a control passage that communicates the rod-side chamber with the liquid tank, and a thrust adjustment portion that is provided on the control passage, and that can drive the expansion unit to expand and contract; and

A shock absorber circuit including an extension side damping passage that communicates the rod side chamber with the piston side chamber, an extension side pressure reducing valve provided on the extension side damping passage that applies resistance to liquid flow from the rod side chamber to the piston side chamber, a compression side damping passage that connects the piston side chamber to the thrust adjustment portion, a compression side pressure reducing valve provided on the compression side damping passage that applies resistance to liquid flow from the piston side chamber to the liquid reservoir, a suction passage that communicates the liquid reservoir with the piston side chamber, a suction check valve provided on the suction passage that allows liquid flow from the liquid reservoir to the piston side chamber,

the thrust adjustment section includes an adjustment passage provided in the middle of the control passage, a pressure reducing valve that opens when the rod-side chamber side pressure reaches a valve opening pressure, and a variable pressure reducing valve that adjusts the valve opening pressure by energization, the pressure reducing valve and the variable pressure reducing valve being arranged in series in this order from the rod-side chamber side in the adjustment passage,

The compression-side damping passage connects the piston-side chamber between the pressure reducing valve and the variable pressure reducing valve of the adjustment passage.

3. A cylinder device as claimed in claim 1 or 2, wherein,

the opening pressure of the extension side pressure reducing valve is higher than a maximum opening pressure selectable by the variable pressure reducing valve in the actuator mode.