Cylinder assembly

Abstract

The cylinder device of the present invention includes: a telescopic unit; a liquid reservoir; an actuator circuit and a damper circuit, wherein the actuator circuit and the damper circuit are disposed between the cylinder of the telescopic unit and the liquid reservoir, the actuator circuit has a thrust adjustment section disposed on a control channel that connects the rod-side chamber to the liquid reservoir, and the damper circuit has a compression-side pressure reducing valve on a compression-side damping channel that connects the piston-side chamber to the thrust adjustment section.

Description

Technical Field

[0001] This invention relates to a cylinder device. Background Technology

[0002] Traditionally, cylinder devices exert thrust to drive an object, assisting in object displacement and suppressing object vibration. For example, when the object is the body of a railway vehicle, the cylinder device is horizontally mounted between the vehicle body and the trolley to suppress lateral vibration relative to the vehicle's forward direction. Furthermore, the cylinder device can be used, for example, as an actuator that actively applies thrust to the vehicle body to suppress vibration, or as a shock absorber that generates damping force to suppress vibration when the vehicle body vibrates and extends or contracts.

[0003] Such a cylinder device, for example as disclosed in JP2016-060438A, includes: a cylinder; a rod that is freely movably inserted into the cylinder; a piston that is movably inserted into the cylinder, connected to the rod, and divides the cylinder into a rod-side chamber and a piston-side chamber filled with hydraulic oil; a reservoir that stores hydraulic oil; a first switching valve disposed on a first channel connecting the rod-side chamber and the piston-side chamber; and a second switching valve, wherein... A second switching valve is disposed on a second channel connecting the piston-side chamber to the reservoir; a pump supplies liquid to the rod-side chamber; a motor drives the pump; a discharge channel connects the rod-side chamber to the reservoir; a variable pressure reducing valve is disposed on the discharge channel and can change the valve opening pressure; a rectifier channel allows liquid flow only from the piston-side chamber to the rod-side chamber; and a suction channel allows liquid flow only from the reservoir to the piston-side chamber.

[0004] This cylinder assembly, after the pump stops and the first and second switching valves are closed, enters damper mode. It can be used as a unidirectional flow damper where, after being subjected to external force to perform a telescopic action, the hydraulic oil sequentially passes through the reservoir, piston-side chamber, and rod-side chamber before reaching the reservoir. Furthermore, the cylinder assembly utilizes a variable pressure relief valve to apply resistance to the flow of hydraulic oil discharged from the cylinder through the discharge channel to the reservoir during the telescopic action, generating a damping force that hinders the telescopic movement. Summary of the Invention

[0005] The problem that the invention aims to solve

[0006] As mentioned earlier, conventional cylinder devices can be used as both actuators and shock absorbers as needed, and in shock absorber mode, they can be used as unidirectional flow shock absorbers. In the shock absorber mode cylinder device, during the extension action, hydraulic oil is discharged from the shrinking rod-side chamber through a variable pressure relief valve to the reservoir, and hydraulic oil is supplied from the reservoir to the enlarged piston-side chamber through the intake passage. Therefore, during the extension action of the shock absorber mode cylinder device, the increased pressure in the rod-side chamber due to the variable pressure relief valve acts on the piston's pressure-bearing surface facing the rod-side chamber, and the reservoir pressure acts on the piston's pressure-bearing surface facing the piston-side chamber. If the reservoir pressure is set to 0, the shock absorber mode cylinder device generates a damping force during the extension action, the value of which is the rod-side chamber pressure multiplied by the piston's rod-side chamber pressure-bearing area.

[0007] On the other hand, when the shock absorber-mode cylinder device performs the retraction action, hydraulic oil moves from the reduced piston-side chamber to the rod-side chamber through the rectifier channel, and the volume of hydraulic oil entering the cylinder through the rod is discharged from the cylinder to the reservoir through the variable pressure relief valve. Therefore, when the shock absorber-mode cylinder device performs the retraction action, the increased cylinder pressure due to the variable pressure relief valve acts equally on both the rod-side chamber and piston-side chamber pressure-bearing surfaces of the piston. The difference between the rod-side chamber pressure-bearing area and the piston-side chamber pressure-bearing area is equal to the rod cross-sectional area. Therefore, the shock absorber-mode cylinder device generates a damping force when performing the retraction action, the value of which is the cylinder pressure multiplied by the rod cross-sectional area.

[0008] The cylinder assembly is used to suppress the lateral vibration of the vehicle body relative to the trolley. Therefore, if the damping force during the extension action deviates from that during the retraction action, the vehicle body will tend to deviate towards the direction of the smaller damping force during repeated extension and retraction, which is not optimal. Therefore, the cylinder assembly used as a unidirectional flow damper sets the rod cross-sectional area to half the piston cross-sectional area. Whether performing an extension or retraction action, as long as the stroke within the cylinder is the same, an equal flow of hydraulic oil through the variable pressure reducing valve can generate equal damping forces during extension and retraction. In summary, the rod and piston diameters in conventional cylinder assemblies are subject to design constraints.

[0009] Here, the working medium of the cylinder device, hydraulic oil, has viscoelasticity. To increase the damping coefficient of the cylinder device to generate a larger damping force, the rigidity of the oil column must be increased. To increase the rigidity of the oil column, the pressure-bearing area of ​​the piston must be increased, so simply increasing the cylinder diameter is sufficient. However, this would also increase the diameter of the rod, and the cylinder device might collide with other equipment on the railway vehicle, making it difficult to increase the cylinder diameter.

[0010] On the other hand, in a two-way flow type shock absorber, during extension, the extension-side pressure reducing valve applies resistance to the flow of hydraulic oil moving from the rod-side chamber to the piston-side chamber to generate extension-side damping force; during contraction, the compression-side pressure reducing valve applies resistance to the flow of hydraulic oil moving from the piston-side chamber to the reservoir to generate compression-side damping force. The extension-side and compression-side damping forces can be arbitrarily set using the extension-side and compression-side pressure reducing valves respectively, so the damping coefficient can be increased without increasing the cylinder diameter. However, in a two-way flow type shock absorber, if hydraulic oil is supplied to the piston-side chamber, the hydraulic oil escapes from the compression-side pressure reducing valve into the reservoir, making it difficult to use as an actuator.

[0011] In summary, conventional cylinder systems suffer from challenges such as requiring larger cylinder sizes or causing problems when used as actuators if the damping coefficient is increased. Furthermore, these challenges extend beyond railway vehicle cylinder systems; they also exist when the cylinder's thrust is applied to vehicles, structures, or machinery other than railway vehicles.

[0012] Therefore, the object of the present invention is to provide a cylinder device that can function as an actuator without being large-scaled and can improve the damping coefficient when used as a shock absorber.

[0013] Solution for solving the problem

[0014] The cylinder device of the present invention comprises: a telescopic unit having a cylinder, a rod, and a piston, the rod being movably inserted into the cylinder, the piston being movably inserted into the cylinder and connected to the rod, dividing the cylinder into a rod-side chamber and a piston-side chamber; a liquid reservoir; an actuator circuit having a pump, an adjustment channel, and a bypass channel, and capable of driving the telescopic unit to extend and retract, the pump supplying liquid from the liquid reservoir to the cylinder, the adjustment channel connecting the rod-side chamber to the liquid reservoir and having a variable pressure reducing valve provided in the middle, the bypass channel connecting the rod-side chamber to the liquid reservoir and having a pressure reducing valve and a bypass channel switching valve connected in series in the middle; and a shock absorber circuit including an extension-side damping channel, an extension-side pressure reducing valve, a compression-side damping channel, a compression-side pressure reducing valve, a suction channel, and a suction check valve, the extension-side damping channel connecting the rod-side chamber and the piston-side chamber. The system is interconnected. The extension-side pressure reducing valve is located on the extension-side damping channel, applying resistance to the liquid flow from the rod-side chamber to the piston-side chamber. The compression-side damping channel connects the piston-side chamber to the pressure reducing valve and the bypass channel switching valve of the bypass channel. The compression-side pressure reducing valve is located on the compression-side damping channel, applying resistance to the liquid flow from the piston-side chamber to the reservoir. The suction channel connects the reservoir to the piston-side chamber. The suction check valve is located on the suction channel, allowing liquid flow from the reservoir to the piston-side chamber. The variable pressure reducing valve and the bypass channel switching valve are solenoid valves driven by the same solenoid. The variable pressure reducing valve can adjust the opening pressure when the solenoid is energized. The bypass channel switching valve is closed when the solenoid is energized and opened when the solenoid is not energized. In the actuator mode of the pump, the bypass channel switching valve is closed to cut off the bypass channel. In the damper mode of the pump, the bypass channel switching valve is opened to open the bypass channel.

[0015] The cylinder device configured in this embodiment can be used as both an actuator and a shock absorber. When used as a shock absorber, regardless of the setting of the rod diameter and the cylinder diameter, the damping force characteristics when performing the extension action and the damping force characteristics when performing the contraction action can be set to the same characteristics by using the setting of the extension-side pressure reducing valve and the compression-side pressure reducing valve.

[0016] Furthermore, this cylinder assembly can utilize an actuator circuit to supply liquid from the pump to the cylinder, and a bypass channel switching valve to cut off the compression-side damping channel as an actuator. Conversely, the pump can be stopped by opening the compression-side damping channel using the bypass channel switching valve, and a damper circuit can be used as a damper. Moreover, when this cylinder assembly is used as a damper, if the telescopic unit extends, a damping force can be generated using the extension-side pressure relief valve; if the telescopic unit retracts, a damping force can be generated using the compression-side pressure relief valve.

[0017] Furthermore, other cylinder devices of the present invention include: a telescopic unit having a cylinder, a rod, and a piston, the rod being movably inserted into the cylinder, the piston being movably inserted into the cylinder and connected to the rod, dividing the cylinder into a rod-side chamber and a piston-side chamber; a reservoir; an actuator circuit having a pump, a control channel, and a thrust adjustment unit, and capable of driving the telescopic unit to extend or retract, the pump supplying liquid from the reservoir to the cylinder, the control channel communicating the rod-side chamber with the reservoir, and the thrust adjustment unit being disposed on the control channel; and a shock absorber circuit including an extension-side damping channel, an extension-side pressure reducing valve, a compression-side damping channel, a compression-side pressure reducing valve, an intake channel, and an intake check valve, the extension-side damping channel communicating the rod-side chamber with the piston-side chamber, and the extension-side pressure reducing valve being disposed on the extension-side damping channel. The compression-side damping channel applies resistance to the liquid flow from the rod-side chamber to the piston-side chamber. The compression-side damping channel connects the piston-side chamber to the thrust adjustment unit. The compression-side pressure reducing valve is installed on the compression-side damping channel to apply resistance to the liquid flow from the piston-side chamber to the reservoir. The suction channel connects the reservoir to the piston-side chamber. The suction check valve is installed on the suction channel to allow liquid flow from the reservoir to the piston-side chamber. The thrust adjustment unit has an adjustment channel, a pressure reducing valve, and a variable pressure reducing valve. The adjustment channel is located in the middle of the control channel. The pressure reducing valve opens when the pressure on the rod-side chamber side reaches the opening pressure. The variable pressure reducing valve can adjust the opening pressure by energizing it. The pressure reducing valve and the variable pressure reducing valve are sequentially connected in series on the adjustment channel from the rod-side chamber side. The compression-side damping channel connects the piston-side chamber to the pressure reducing valve and the variable pressure reducing valve in the adjustment channel.

[0018] Other cylinder devices of the present invention configured in this way can be used as both actuators and shock absorbers. When used as a shock absorber, regardless of the setting of the rod diameter and the cylinder diameter, the damping force characteristics when performing the extension action and the damping force characteristics when performing the contraction action can be set to the same characteristics by using the setting of the extension-side pressure reducing valve and the compression-side pressure reducing valve.

[0019] Even if the thrust adjustment unit does not have a switching valve that cuts off the compression-side damping channel in actuator mode, the cylinder device configured in this way can generate compression-side damping force in shock absorber mode by using the compression-side pressure reducing valve. The configuration of the thrust adjustment unit becomes simple and does not require a switching valve, thus reducing manufacturing costs. Attached Figure Description

[0020] Figure 1 This is a circuit diagram of the cylinder device in the first embodiment.

[0021] Figure 2 This diagram shows the state in which the cylinder assembly is installed between the body of a railway vehicle and the bogie.

[0022] Figure 3 This is a circuit diagram of the cylinder device in the second embodiment. Detailed Implementation

[0023] The present invention will now be described based on the embodiments shown in the figures. In the cylinder devices of each embodiment, components and members with common symbols have the same configuration. Therefore, to avoid repetition, details of configurations described in detail in one embodiment of the cylinder device will be omitted in the descriptions of cylinder devices in other embodiments. Furthermore, in describing the cylinder device of the present invention, each embodiment is described using a cylinder device suitable for railway vehicles as an example; however, the cylinder device of the present invention can also be used to drive vehicles, structures, buildings, and even machinery other than railway vehicles, and to suppress vibrations.

[0024] <First Implementation Method>

[0025] The present invention will now be described based on the embodiments shown in the figures. Figure 1 As shown, the cylinder device C of the first embodiment includes and is composed of the following parts: a telescopic unit 1, a liquid reservoir 7, an actuator circuit A, and a shock absorber circuit D. Figure 2 As shown, in this embodiment, two cylinder devices C are installed side by side between the body S and the trolley B of the railway vehicle T to suppress the horizontal vibration of the body S. However, one cylinder device C can also be installed between the body S and the trolley B.

[0026] The following will describe the various parts of the cylinder assembly C. The telescopic unit 1 includes: a cylinder 2; a rod 3, which is movably inserted into the cylinder 2; and a piston 4, which is movably inserted into the cylinder 2 and connected to the rod 3, dividing the cylinder 2 into a rod-side chamber 5 and a piston-side chamber 6.

[0027] Furthermore, the rod-side chamber 5 and the piston-side chamber 6 are filled with hydraulic oil as a liquid, and the reservoir 7 is filled with gas in addition to hydraulic oil. Besides hydraulic oil, water and aqueous solutions can also be used as the liquid. Additionally, while it is not specifically necessary to create a pressurized state by compressing and filling gas into the reservoir 7, a pressurized state can still be achieved.

[0028] Cylinder 2 is cylindrical, and its Figure 1 The right end of the middle section is covered by 19. Figure 1 A ring-shaped rod guide 20 is installed at the left end. Furthermore, a rod 3, which is 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 connected to a piston 4, which is movably inserted into the cylinder 2, and the other end protrudes outside the cylinder 2 and is axially movable relative to the cylinder 2.

[0029] Furthermore, the cylinder assembly C includes an outer cylinder 21 that covers the outer periphery of the cylinder 2. The outer cylinder 21... Figure 1 The left and right ends, like cylinder 2, are closed by cover 19 and rod guide 20, and a liquid storage tank 7 is formed by the annular gap between the outer cylinder 21 and cylinder 2. The rod 3... Figure 1 The cover 19, which is closed at the left end of the middle section and the right end of the cylinder 2, is provided with a mounting part (not shown) so that the cylinder device C can be installed between the body S of the railway vehicle T and the trolley B.

[0030] Actuator circuit A is a circuit equipped with a pump 14 to drive the telescopic unit 1 to extend and retract. The pump 14 is located 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, actuator circuit A supplies hydraulic oil to the cylinder 2, selects one of the extension or retraction directions for the telescopic unit 1, and causes the telescopic unit 1 to generate thrust in the selected direction. This thrust can be adjusted.

[0031] Specifically, such as Figure 1 As shown, actuator circuit A includes: a pump 14 disposed between cylinder 2 and reservoir 7, supplying hydraulic oil to rod-side chamber 5; a motor 15 driving pump 14; a control channel 40 connecting rod-side chamber 5 and reservoir 7; a thrust adjustment unit FT disposed on control channel 40; a first channel 10 connecting rod-side chamber 5 and piston-side chamber 6; a first switching valve 11 disposed on first channel 10; a second channel 12 connecting piston-side chamber 6 and reservoir 7; and a second switching valve 13 disposed on second channel 12.

[0032] Pump 14 is driven by motor 15, and in this embodiment, hydraulic oil is sprayed out in only one direction in cylinder device C. The outlet of pump 14 is connected to rod-side chamber 5 via supply channel 22, which connects rod-side chamber 5 and reservoir 7, and the inlet is connected to reservoir 7 via supply channel 22. Therefore, after pump 14 is driven by motor 15, it draws in hydraulic oil from reservoir 7 and supplies hydraulic oil to rod-side chamber 5.

[0033] As mentioned earlier, pump 14 sprays hydraulic oil in only one direction without switching rotation direction. Therefore, there are no issues such as changes in spray volume during rotation switching, and inexpensive gear pumps can be used. Furthermore, since the rotation direction of pump 14 is always the same, the drive source for pump 14, i.e., motor 15, is not required to have high responsiveness to rotation switching, and correspondingly, inexpensive motors can also be used for motor 15. In addition, a check valve 23 is provided on the supply channel 22 to prevent hydraulic oil from flowing back from the rod-side chamber 5 to pump 14.

[0034] Furthermore, in the actuator circuit A of this embodiment, a first switching valve 11 is provided on the first channel 10 that connects the rod-side chamber 5 and the piston-side chamber 6, and a second switching valve 13 is provided on the second channel 12 that connects the piston-side chamber 6 and the liquid storage tank 7.

[0035] In this embodiment, the first switching valve 11 is an electromagnetic switching valve, comprising the following components: a valve body 11a, which has a connecting position 11b and a cutting-off position 11c. The connecting position 11b opens the first channel 10 to connect the rod-side chamber 5 and the piston-side chamber 6, and the cutting-off position 11c cuts off the connection between the rod-side chamber 5 and the piston-side chamber 6; a spring 11d, which applies force to the valve body 11a to select the cutting-off position 11c; and a solenoid 11e, which, when energized, counteracts the spring 11d to switch the valve body 11a to the connecting position 11b.

[0036] In this embodiment, the second switching valve 13 is an electromagnetic switching valve, comprising the following components: a valve body 13a, which has a connecting position 13b and a cutting-off position 13c. The connecting position 13b opens the second channel 12 to connect the piston-side chamber 6 with the liquid storage tank 7, and the cutting-off position 13c cuts off the connection between the piston-side chamber 6 and the liquid storage tank 7; a spring 13d, which applies force to the valve body 13a to select the cutting-off position 13c; and a solenoid 13e, which, when energized, counteracts the spring 13d to switch the valve body 13a to the connecting position 13b.

[0037] The thrust adjustment unit FT includes: an adjustment channel P1 and a bypass channel P2, which are connected in parallel to the control channel 40 that connects the rod-side chamber 5 to the liquid storage tank 7; a variable pressure reducing valve 41, which is installed on the adjustment channel P1; a pressure reducing valve 43 and a bypass channel switching valve 44, which are sequentially connected in series on the bypass channel P2 from the rod-side chamber 5 side.

[0038] Thus, in the cylinder device C of the first embodiment, the rod-side chamber 5 and the liquid storage tank 7 are connected through a control channel 40, an adjustment channel P1 located in the middle of the control channel 40, and a bypass channel P2. Moreover, as mentioned above, a variable pressure reducing valve 41 with adjustable valve opening pressure is provided on the adjustment channel P1, and a pressure reducing valve 43 and a bypass channel switching valve 44 are connected in series on the bypass channel P2.

[0039] The pressure reducing valve 43 comprises the following parts: a valve body 43a, which is disposed on the bypass passage P2; a spring 43b, which applies force to the valve body 43a to cut off the bypass passage P2; and a pilot passage 43c, which applies the upstream side (rod side chamber side) pressure of the valve body 43a to the valve body 43a, causing it to exert a force against the spring 43b in the valve opening direction. The opening pressure of the pressure reducing valve 43 is set to a predetermined opening pressure based on the force exerted by the spring 43b on the valve body 43a.

[0040] Furthermore, when the bypass channel switch valve 44 located downstream of the pressure reducing valve 43 is open, if the pressure in the upstream rod side chamber 5 of the bypass channel P2 acting on the valve body 43a exceeds the pressure reducing pressure (opening pressure) of the pressure reducing valve 43, the force of this pressure pushing the valve body 43a overcomes the force of the spring 43b on the valve body 43a, the valve body 43a retracts, and the pressure reducing valve 43 opens the bypass channel P2.

[0041] The bypass channel switching valve 44 comprises the following parts: a valve body 44a, which is located downstream of the pressure reducing valve 43 in the bypass channel P2, i.e., on the reservoir side, and is operable to open and close; a spring 44b, which applies force to the valve body 44a to open the bypass channel P2; and a solenoid Sol, which, when energized, generates a thrust opposing the spring 44b, switching the valve body 44a to the position of cutting off the bypass channel P2. Thus, the bypass channel switching valve 44 is a solenoid valve. When a current of a specified value or higher is applied to the solenoid Sol, if the solenoid Sol generates a thrust exceeding the force of the spring 44b, the bypass channel P2 is cut off.

[0042] Furthermore, when the solenoid Sol is not energized and no current is supplied, the valve body 44a of the bypass channel switch valve 44 is forced by the spring 44b to select the position where the bypass channel P2 is open. That is, when the solenoid Sol is not energized, the bypass channel switch valve 44 opens, and the bypass channel P2 is opened.

[0043] The variable pressure reducing valve 41 comprises the following parts: a valve body 41a, which is disposed on an adjustment channel P1; a spring 41b, which applies force to the valve body 41a to cut off the adjustment channel P1; a pilot channel 41c, which applies the upstream side (rod side chamber side) pressure of the valve body 41a to the valve body 41a, causing it to exert a force against the spring 41b in the valve opening direction; and a solenoid Sol, which generates a thrust against the spring 41b when energized. The variable pressure reducing valve 41 is a solenoid valve, and the valve opening pressure can be adjusted by regulating the amount of current flowing through the solenoid Sol. Furthermore, the thrust of the solenoid Sol is transmitted to the valve body 41a of the variable pressure reducing valve 41 through the valve body 44a. More specifically, if a current of a specified value or higher is supplied to the solenoid Sol, the valve body 44a of the bypass channel switching valve 44 cuts off the bypass channel P2 and contacts the valve body 41a of the variable pressure reducing valve 41, transmitting the thrust of the solenoid Sol to the valve body 41a.

[0044] Furthermore, if the pressure in the upstream rod side chamber 5 of the control channel 40 acting on the valve body 41a exceeds the pressure reduction pressure (opening pressure) of the variable pressure reducing valve 41, then the pressure and the force of the solenoid Sol pushing the valve body 41a overcome the combined force of the force of the spring 41b on the valve body 41a and the force of the spring 44b on the valve body 44a, the valve body 41a retracts, and the variable pressure reducing valve 41 opens the adjustment channel P1.

[0045] Furthermore, for the variable pressure reducing valve 41, increasing the current supplied to the solenoid Sol increases the thrust generated by the solenoid Sol. Therefore, if the current supplied to the solenoid Sol is maximized, the opening pressure of the variable pressure reducing valve 41 becomes minimum; conversely, if no current is supplied to the solenoid Sol, the opening pressure of the variable pressure reducing valve 41 becomes maximum. Moreover, if the current supplied to the solenoid Sol is adjusted to a value above a specified value and the current is changed, the opening pressure of the variable pressure reducing valve 41 can be changed even with the bypass channel switching valve 44 closed. Thus, the variable pressure reducing valve 41 and the bypass channel switching valve 44 are solenoid valves that share one solenoid Sol and are driven by the same solenoid Sol. Therefore, the thrust of the solenoid Sol can be applied to the valve bodies 41a and 44a of the variable pressure reducing valve 41 and the bypass channel switching valve 44, respectively.

[0046] Furthermore, when the solenoid Sol is energized, the opening pressure of the variable pressure reducing valve 41 can be adjusted according to the amount of current supplied to the solenoid Sol, and the bypass channel switch valve 44 can also be closed. Conversely, when the solenoid Sol is not energized and no current is supplied, the opening pressure of the variable pressure reducing valve 41 can be adjusted to the maximum, and the bypass channel switch valve 44 can be opened.

[0047] Furthermore, regardless of the on / off states of the first switching valve 11 and the second switching valve 13, if there is an excessive input in the telescopic unit 1 in the telescopic direction, and the pressure in the rod-side chamber 5 exceeds the valve opening pressure, the variable pressure reducing valve 41 opens the adjustment channel P1, connecting the rod-side chamber 5 to the liquid storage tank 7. Thus, for excessive input to the telescopic unit 1, the variable pressure reducing valve 41 discharges the pressure in the rod-side chamber 5 to the liquid storage tank 7, protecting the entire system of the cylinder device C.

[0048] Next, the shock absorber circuit D includes: an extension-side damping channel 24, which connects the rod-side chamber 5 and the piston-side chamber 6; an extension-side pressure-reducing valve 25, which is disposed on the extension-side damping channel 24 and applies resistance to the flow of hydraulic oil from the rod-side chamber 5 to the piston-side chamber 6; a compression-side damping channel 26, which connects the piston-side chamber 6 to the thrust adjustment unit FT; a first compression-side pressure-reducing valve 27, which acts as a compression-side pressure-reducing valve and is disposed on the compression-side damping channel 26 to apply resistance to the flow of hydraulic oil from the piston-side chamber 6 to the reservoir 7; and a suction channel 28, which connects the reservoir 7 to the piston-side chamber 6. The piston-side chamber 6 is connected; a suction check valve 29 is installed on the suction channel 28, allowing hydraulic oil to flow from the reservoir 7 to the piston-side chamber 6; an extension-side suction channel 30 connects the reservoir 7 to the rod-side chamber 5; an extension-side check valve 31 is installed on the extension-side suction channel 30, allowing only hydraulic oil to flow from the reservoir 7 to the rod-side chamber 5; a compression-side channel 32 connects the piston-side chamber 6 to the rod-side chamber 5; and a second compression-side pressure reducing valve 33 is installed on the compression-side channel 32, applying resistance to the flow of hydraulic oil from the piston-side chamber 6 to the rod-side chamber 5.

[0049] An extension-side damping channel 24 is provided on the piston 4, connecting the rod-side chamber 5 and the piston-side chamber 6. Furthermore, an extension-side pressure-reducing valve 25 is provided on the piston 4. If the pressure inside the rod-side chamber 5 exceeds the pressure inside the piston-side chamber 6, and the pressure difference between the rod-side chamber 5 and the piston-side chamber 6 reaches the valve opening pressure, the extension-side pressure-reducing valve 25 opens, applying resistance to the flow of hydraulic oil from the rod-side chamber 5 to the piston-side chamber 6. Conversely, for the flow of hydraulic oil from the piston-side chamber 6 to the rod-side chamber 5 within the extension-side damping channel 24, the extension-side pressure-reducing valve 25 closes, cutting off the extension-side damping channel 24. Therefore, the extension-side damping channel 24, using the extension-side pressure-reducing valve 25, is configured as a unidirectional passage allowing only the flow of hydraulic oil from the rod-side chamber 5 to the piston-side chamber 6.

[0050] The opening pressure of the extension-side pressure reducing valve 25 is set to be greater than or equal to the difference between the pressure in the rod-side chamber 5 and the pressure in the piston-side chamber 6 when the telescopic unit 1 generates maximum thrust towards the contraction side using actuator circuit A. Therefore, even if the pump 14 driving actuator circuit A generates maximum thrust in the contraction direction of the telescopic unit 1, the extension-side pressure reducing valve 25 will not open, but will remain in a state where the extension-side damping channel 24 is cut off.

[0051] The compression-side damping channel 26 connects the piston-side chamber 6 to the thrust adjustment unit FT. Specifically, the compression-side damping channel 26 connects the piston-side chamber 6 between the pressure reducing valve 43 and the bypass channel switching valve 44 of the bypass channel P2. Therefore, if the bypass channel switching valve 44 is open, the piston-side chamber 6 is connected to the reservoir 7 via the compression-side damping channel 26, the bypass channel switching valve 44, the bypass channel P2, and downstream of the thrust adjustment unit FT of the control channel 40. Conversely, if the bypass channel switching valve 44 is closed, the connection between the piston-side chamber 6 and the reservoir 7 via the compression-side damping channel 26 is cut off. Since the compression-side damping channel 26 is connected between the pressure reducing valve 43 and the bypass channel switching valve 44 of the bypass channel P2, the opening and closing of the compression-side damping channel 26 can be switched by switching the bypass channel switching valve 44 located downstream of the compression-side damping channel 26.

[0052] Furthermore, when the bypass channel switch valve 44 is open, if the pressure inside the piston-side chamber 6 exceeds the pressure inside the reservoir 7, and the pressure difference between the piston-side chamber 6 and the reservoir 7 reaches the valve opening pressure, then the first compression-side pressure reducing valve 27, acting as a compression-side pressure reducing valve, opens, applying resistance to the flow of hydraulic oil from the piston-side chamber 6 to the reservoir 7. Conversely, for the flow of hydraulic oil from the reservoir 7 to the piston-side chamber 6 in the compression-side damping channel 26, the first compression-side pressure reducing valve 27 closes, cutting off the compression-side damping channel 26. Therefore, the compression-side damping channel 26 is configured as a one-way passage that allows only the flow of hydraulic oil from the piston-side chamber 6 to the reservoir 7 via the first compression-side pressure reducing valve 27. Additionally, when the bypass channel switch valve 44 is closed, the connection between the piston-side chamber 6 and the reservoir 7 via the compression-side damping channel 26 is cut off, therefore the first compression-side pressure reducing valve 27 will not open.

[0053] Next, the suction passage 28 connects the reservoir 7 to the piston-side chamber 6. Furthermore, if the pressure inside the reservoir 7 exceeds the pressure inside the piston-side chamber 6, the suction check valve 29 opens, allowing hydraulic oil to flow from the reservoir 7 to the piston-side chamber 6 without applying significant resistance. Conversely, for hydraulic oil flowing from the piston-side chamber 6 to the reservoir 7 through the suction passage 28, the suction check valve 29 closes, cutting off the suction passage 28. Therefore, the suction passage 28 is configured as a one-way passage that allows only the flow of hydraulic oil from the reservoir 7 to the piston-side chamber 6 using the suction check valve 29.

[0054] Furthermore, the extended-side suction passage 30 connects the reservoir 7 to the rod-side chamber 5. Additionally, if the pressure inside the reservoir 7 exceeds the pressure inside the rod-side chamber 5, the extended-side check valve 31 opens, allowing hydraulic oil to flow from the reservoir 7 to the rod-side chamber 5 without applying significant resistance. Conversely, for hydraulic oil flow from the rod-side chamber 5 to the reservoir 7 within the extended-side suction passage 30, the extended-side check valve 31 closes, cutting off the extended-side suction passage 30. Therefore, the extended-side suction passage 30 is configured as a unidirectional passage that allows only the flow of hydraulic oil from the reservoir 7 to the rod-side chamber 5 using the extended-side check valve 31.

[0055] Furthermore, a compression-side passage 32 is provided on the piston 4, connecting the piston-side chamber 6 and the rod-side chamber 5. Additionally, a second compression-side pressure-reducing valve 33 is provided on the piston 4. If the pressure inside the piston-side chamber 6 exceeds the pressure inside the rod-side chamber 5, and the pressure difference between the piston-side chamber 6 and the rod-side chamber 5 reaches the valve opening pressure, the second compression-side pressure-reducing valve 33 opens, applying resistance to the flow of hydraulic oil from the piston-side chamber 6 to the rod-side chamber 5. Conversely, for the flow of 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 closes, cutting off the compression-side passage 32. Therefore, the compression-side passage 32 is configured as a unidirectional passage that allows only the flow of hydraulic oil from the piston-side chamber 6 to the rod-side chamber 5 using the second compression-side pressure-reducing valve 33.

[0056] The cylinder assembly C is configured as described above. The operation of the cylinder assembly C will now be explained. First, the actuator mode, in which the cylinder assembly C is used as an actuator via actuator circuit A, will be explained. When the cylinder assembly C generates thrust in the extension direction, the first switching valve 11 is adjusted to the connected position 11b, and the second switching valve 13 is adjusted to the cut-off position 13c. The pump 14 is driven by the motor 15 to supply hydraulic oil from the reservoir 7 to the cylinder 2. Furthermore, a current exceeding a specified value is applied to the solenoid Sol, the bypass channel switching valve 44 is closed, the bypass channel P2 is cut off, and the opening pressure of the variable pressure reducing valve 41 is adjusted according to the thrust required by the cylinder assembly C.

[0057] Thus, when the first switching valve 11 is opened, the rod-side chamber 5 and the piston-side chamber 6 are connected through the first channel 10, allowing hydraulic oil to be supplied from the pump 14 to both chambers. Furthermore, the bypass channel switching valve 44 is closed, so the compression-side damping channel 26 is cut off, preventing the hydraulic oil supplied to the cylinder 2 from moving from the piston-side chamber 6 to the reservoir 7. Therefore, when the cylinder assembly C is used as the actuator in actuator mode, the compression-side damping channel 26 is cut off by the bypass channel switching valve 44.

[0058] Therefore, if the first switching valve 11 is adjusted to the connected position 11b and the second switching valve 13 is adjusted to the cut-off position 13c, and the pump 14 is driven by the motor 15, the hydraulic oil supplied from the pump 14 to the cylinder 2 will push the piston 4 relative to the cylinder 2. Figure 1 The left side pushes, so the cylinder device C generates a thrust in the extension direction.

[0059] Furthermore, if the pressure in the rod-side chamber 5 and the piston-side chamber 6 exceeds the opening pressure of the variable pressure reducing valve 41, the variable pressure reducing valve 41 opens, and hydraulic oil is discharged to the reservoir 7 via the adjustment channel P1. The pressure in the rod-side chamber 5 and the piston-side chamber 6 then becomes equal to the opening pressure of the variable pressure reducing valve 41. Thus, the variable pressure reducing valve 41 adjusts the pressure of the hydraulic oil supplied from the pump 14 to the cylinder 2 by adjusting its opening pressure. Therefore, the cylinder assembly C generates a thrust in the extension direction, the value of which is the difference in pressure-bearing area between the piston-side chamber and the rod-side chamber of the piston 4 multiplied by the opening pressure of the variable pressure reducing valve 41. This thrust can be adjusted by regulating the opening pressure of the variable pressure reducing valve 41. Additionally, in this state, even if the telescopic unit 1 is forced to contract by an external force, the pressure in the rod-side chamber 5 and the piston-side chamber 6 can be controlled to be equal to the opening pressure of the variable pressure reducing valve 41, thus generating a thrust in the extension direction that inhibits contraction.

[0060] During the process of the cylinder device C generating thrust in the extension direction, the telescopic unit 1 is subjected to external force and contracts at high speed. When there is abnormal high pressure in the piston side chamber 6, the second compression side pressure reducing valve 33 opens, causing the hydraulic oil in the piston side chamber 6 to move to the rod side chamber 5, so the cylinder device C is protected.

[0061] In contrast, when the cylinder assembly C generates a thrust in the contraction direction, the first switching valve 11 is adjusted to the cut-off position 11c, the second switching valve 13 is adjusted to the connected position 13b, and the pump 14 is driven by the motor 15 to supply hydraulic oil from the reservoir 7 to the rod-side chamber 5. Furthermore, a current exceeding a specified value is applied to the solenoid Sol, the bypass channel switching valve 44 is closed, the bypass channel P2 is cut off, and the opening pressure of the variable pressure reducing valve 41 is adjusted according to the thrust required by the cylinder assembly C.

[0062] Thus, when the second switching valve 13 opens, the piston-side chamber 6 and the reservoir 7 are connected through the second channel 12. The first switching valve 11 closes, cutting off the connection between the rod-side chamber 5 and the piston-side chamber 6. Therefore, the hydraulic oil injected by the pump 14 is only supplied to the rod-side chamber 5. In addition, the bypass channel switching valve 44 closes, so the compression-side damping channel 26 is cut off, but the piston-side chamber 6 and the reservoir 7 are still connected through the second channel 12.

[0063] Therefore, if the first switching valve 11 is adjusted to the cut-off position 11c and the second switching valve 13 is adjusted to the connected 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 will push the piston 4 relative to the cylinder 2. Figure 1 The cylinder C generates a contraction thrust due to the pressure applied from the right. Furthermore, the value of this contraction thrust is equal to the product of the pressure area on the rod side of piston 4 multiplied by the opening pressure of the variable pressure reducing valve 41, minus the product of the pressure area on the piston side of piston 4 multiplied by the pressure in the reservoir 7. This thrust can be adjusted by regulating the opening pressure of the variable pressure reducing valve 41. In this state, even if the telescopic unit 1 is forced to extend by an external force, the pressure in the rod side chamber 5 can be controlled to be equal to the opening pressure of the variable pressure reducing valve 41, thus generating a contraction thrust that inhibits extension.

[0064] Furthermore, as mentioned above, when the cylinder device C of this embodiment generates a thrust in the contraction direction, hydraulic oil needs to be supplied to the rod-side chamber 5 while 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 open, the extension-side damping channel 24 of the damper circuit D allows hydraulic oil to flow from the rod-side chamber 5 to the piston-side chamber 6. Therefore, when the cylinder device C of this embodiment generates a thrust in the contraction direction, if the extension-side pressure reducing valve 25 is open, hydraulic oil escapes from the rod-side chamber 5 to the piston-side chamber 6, thus reducing efficiency. However, the opening pressure of the extension-side pressure reducing valve 25 is set to be greater than or equal to the difference between the pressure in the rod-side chamber 5 and the pressure in the piston-side chamber 6 when the telescopic unit 1 generates the maximum thrust to the contraction side using the actuator circuit A. The maximum thrust in the contraction direction of the cylinder device C in actuator mode is generated when the variable pressure reducing valve 41 sets the opening pressure to the maximum. Therefore, when the cylinder device C of this embodiment is used as an actuator to generate thrust in the contraction direction, even if the opening pressure of the variable pressure reducing valve 41 is set to the maximum, the extension-side pressure reducing valve 25 will not open, preventing hydraulic oil from moving from the rod-side chamber 5 to the piston-side chamber 6 through the extension-side damping channel 24. Thus, if the opening pressure of the extension-side pressure reducing valve 25 is set to be greater than or equal to the difference between the pressure in the rod-side chamber 5 and the pressure in the piston-side chamber 6 when the telescopic unit 1 generates maximum thrust in the contraction direction using actuator circuit A, the cylinder device C can efficiently generate thrust in the contraction direction with less energy consumption. As mentioned above, in the cylinder device C of this embodiment, even if the variable pressure reducing valve 41, which controls the pressure in the rod-side chamber 5, is set to the maximum opening pressure, the extension-side pressure reducing valve 25 only needs to remain closed. Therefore, the opening pressure of the extension-side pressure reducing valve 25 only needs to be higher than the maximum opening pressure of the variable pressure reducing valve 41. In this case, the opening pressure of the extended side pressure reducing valve 25 is not the maximum opening pressure of the variable pressure reducing valve 41 in terms of hardware, but can be higher than the maximum opening pressure that can be selected in terms of control of the variable pressure reducing valve 41 in actuator mode.

[0065] In addition, as mentioned above, from the point of view of efficiency, the opening pressure of the extension side pressure reducing valve 25 can be set to be greater than or equal to the difference between the pressure in the rod side chamber 5 and the pressure in the piston side chamber 6 when the telescopic unit 1 generates the maximum thrust to the contraction side using the actuator circuit A. However, even if the opening pressure is set to be less than the difference, the cylinder device C can still be used as an actuator to generate thrust in the contraction direction.

[0066] During the process of the cylinder device C generating a thrust in the contraction direction, the telescopic unit 1 is subjected to external force and extends at high speed. When there is abnormal high pressure in the rod side chamber 5, the extension side pressure reducing valve 25 opens, causing the hydraulic oil in the rod side chamber 5 to move to the piston side chamber 6, so the cylinder device C is protected.

[0067] Thus, the cylinder device C can generate thrust in any direction, either in the extension or contraction direction, within the adjustment range of the opening pressure of the variable pressure reducing valve 41, by switching the first switching valve 11 and the second switching valve 13 and adjusting the opening pressure of the variable pressure reducing valve 41. Therefore, in actuator mode, the cylinder device C can be used as an actuator to suppress the vibration of the vehicle body S by driving the pump 14 and controlling the first switching valve 11, the second switching valve 13, and the variable pressure reducing valve 41.

[0068] Next, the damper mode of using cylinder assembly C as a damper using damper circuit D will be explained. When cylinder assembly C is switched to damper mode, the first switch valve 11 is switched to the off position 11c, the second switch valve 13 is switched to the off position 13c, the motor 15 is not driven, and the pump 14 is stopped. In addition, the solenoid Sol is de-energized, and in the de-energized state, the bypass channel switch valve 44 is opened, opening the bypass channel P2.

[0069] In this state, the connection between the rod-side chamber 5 and the piston-side chamber 6 via the first channel 10 is cut off, and the connection between the piston-side chamber 6 and the reservoir 7 via the second channel 12 is also cut off. Furthermore, after the solenoid Sol is de-energized, the bypass channel switch valve 44 opens, thus connecting the piston-side chamber 6 and the reservoir 7 via the compression-side damping channel 26. Therefore, when the cylinder assembly C is used as a shock absorber in shock absorber mode, the compression-side damping channel 26 is opened after the bypass channel switch valve 44 is opened.

[0070] Furthermore, when the cylinder assembly C is in damper mode, if the telescopic unit 1 is extended by an external force, the piston 4 will move relative to the cylinder 2. Figure 1The telescopic unit 1 moves to the left, shrinking the rod-side chamber 5 and expanding the piston-side chamber 6. The hydraulic oil in the shrunken rod-side chamber 5 is resisted by one or both of the pressure-reducing valve 43 in the bypass channel P2 and the extension-side pressure-reducing valve 25 in the extension-side damping channel 24, and moves to the reservoir 7 or the expanded piston-side chamber 6. When the telescopic unit 1 extends, the rod 3 retracts from the cylinder 2, resulting in insufficient hydraulic oil in the cylinder 2. However, after the suction check valve 29 opens, the insufficient hydraulic oil is supplied from the reservoir 7 to the piston-side chamber 6 through the suction channel 28. Thus, if the cylinder device C enters the damper mode and the telescopic unit 1 extends, the pressure in the rod-side chamber 5 increases due to the pressure-reducing valve 43 and the extension-side pressure-reducing valve 25, and the pressure in the piston-side chamber 6 becomes equal to the reservoir pressure. Therefore, the cylinder device C generates a damping force in the direction that hinders the extension of the telescopic unit 1. The value of this force is equal to the product of the pressure area on the rod side chamber of piston 4 multiplied by the pressure inside the rod side chamber 5, minus the product of the pressure area on the piston side chamber of piston 4 multiplied by the pressure in the liquid storage tank 7.

[0071] Furthermore, when the cylinder assembly C is set to shock absorber mode, if the telescopic unit 1 is contracted by an external force, the piston 4 will move relative to the cylinder 2. Figure 1The telescopic unit 1 moves to the right, shrinking the piston-side chamber 6 and expanding the rod-side chamber 5. Hydraulic oil in the shrunken piston-side chamber 6 moves to the expanded rod-side chamber 5 through the second compression-side pressure-reducing valve 33 in the compression-side channel 32. When the telescopic unit 1 retracts, the rod 3 enters the cylinder 2, resulting in excess hydraulic oil in the cylinder 2. However, after the first compression-side pressure-reducing valve 27 opens, the excess hydraulic oil is discharged from the piston-side chamber 6 to the reservoir 7 through the compression-side damping channel 26. Thus, if the cylinder device C enters the damper mode and the telescopic unit 1 retracts, the pressure in the piston-side chamber 6 increases due to the first compression-side pressure-reducing valve 27 and the second compression-side pressure-reducing valve 33, while the pressure in the rod-side chamber 5 decreases, making the pressure in the piston-side chamber 6 higher than that in the rod-side chamber 5. Therefore, the cylinder device C generates a damping force in the direction that hinders the contraction of the telescopic unit 1. The value of this force is equal to the product of the piston-side chamber pressure area of ​​piston 4 multiplied by the pressure inside piston-side chamber 6, minus the product of the rod-side chamber pressure area of ​​piston 4 multiplied by the pressure inside rod-side chamber 5. Furthermore, in this embodiment, the cylinder device C includes an extension-side intake channel 30 and an extension-side check valve 31. Therefore, when the telescopic unit 1 of the cylinder device C in shock absorber mode contracts, if the pressure inside rod-side chamber 5 is lower than the pressure in the reservoir, the extension-side check valve 31 opens, and hydraulic oil is supplied from the reservoir 7 to rod-side chamber 5. Thus, when the cylinder device C in this embodiment contracts in shock absorber mode, a negative pressure does not form inside rod-side chamber 5, preventing aeration and the occurrence of damping force lag during the transition of the telescopic unit 1 from contraction to extension.

[0072] Thus, in shock absorber mode, if the telescopic unit 1 is subjected to an external force and extends or retracts, the cylinder device C generates a damping force that hinders the extension or retraction of the telescopic unit 1. Furthermore, in shock absorber mode, the cylinder device C generates a damping force using one or both of the pressure reducing valve 43 and the extension-side pressure reducing valve 25 when the telescopic unit 1 extends, and generates a damping force using the first compression-side pressure reducing valve 27 and the second compression-side pressure reducing valve 33 when the telescopic unit 1 retracts. Therefore, the damping force characteristics relative to the piston speed generated during the extension action of the cylinder device C in shock absorber mode are set using the pressure reducing valve 43 and the extension-side pressure reducing valve 25, and the damping force characteristics relative to the piston speed generated during the retraction action of the cylinder device C in shock absorber mode are set using the first compression-side pressure reducing valve 27 and the second compression-side pressure reducing valve 33. Therefore, the damping force characteristics during the extension and retraction actions can be set independently.

[0073] That is, regardless of the settings of the pressure-bearing area on the rod side and the piston side of the piston 4, the damping force characteristics of the cylinder device C in this embodiment of the shock absorber mode during both the extension and contraction actions can be independently adjusted using 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. In other words, when the two damping force characteristics of the cylinder device C in this embodiment of the shock absorber mode during both the extension and contraction actions are set to be the same, it is not necessary to set the cross-sectional area of ​​the rod 3 to half the cross-sectional area of ​​the piston 4. After arbitrarily determining the diameters of the rod 3 and the piston 4 (the diameter of the cylinder 2) within the strength allowable range, it is only necessary to adjust the two damping force characteristics to be the same using 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.

[0074] Furthermore, the shock absorber circuit D in this embodiment includes an extension-side intake channel 30 and an extension-side check valve 31. When the telescopic unit 1 of the shock absorber-mode cylinder device C performs a retraction action, hydraulic oil is allowed to flow from the reservoir 7 to the enlarged rod-side chamber 5, so the compression-side channel 32 and the second compression-side pressure-reducing valve 33 can be omitted. In this case, by setting the pressure-reducing valve 43, the extension-side pressure-reducing valve 25, and the first compression-side pressure-reducing valve 27, the two damping force characteristics of the cylinder device C in the shock absorber-mode of this embodiment during the extension and retraction actions can be adjusted to be the same.

[0075] However, when the compression side passage 32 and the second compression side pressure reducing valve 33 are provided, the following advantages are available: when the telescopic unit 1 of the shock absorber mode cylinder device C performs the retraction action, if the pressure in the piston side chamber 6 is abnormally high, the second compression side pressure reducing valve 33 will open, allowing the hydraulic oil in the piston side chamber 6 to move to the rod side chamber 5, which can protect the cylinder device C.

[0076] Furthermore, the shock absorber circuit D of this embodiment has a compression side channel 32 and a second compression side pressure reducing valve 33. Therefore, when the telescopic unit 1 of the shock absorber mode cylinder device C performs the retraction action, 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 channel 32 will cause negative pressure to form in the rod side chamber 5, the extension side suction channel 30 and the extension side check valve 31 can be omitted.

[0077] Furthermore, a check valve that does not exert too much resistance on the hydraulic oil passing through is installed on the compression side channel 32 instead of the second compression side pressure reducing valve 33. When the telescopic unit 1 of the shock absorber mode cylinder device C performs a retraction action, the damping force can be generated solely by the resistance of the first compression side pressure reducing valve 27. In this case, the damping force characteristic relative to the piston speed generated when the shock absorber mode cylinder device C performs an extension action can be set using the extension side pressure reducing valve 25, and the damping force characteristic relative to the piston speed generated when the shock absorber mode cylinder device C performs a retraction action can be set using the first compression side pressure reducing valve 27. Therefore, regardless of the settings of the rod-side chamber-side pressure area and the piston-side chamber-side pressure area of ​​the piston 4, the damping force characteristics of the shock absorber mode cylinder device C during the extension action and the retraction action can be set to the same characteristics.

[0078] In summary, the cylinder device C of this embodiment includes: a telescopic unit 1, which has a cylinder 2, a rod 3, and a piston 4. The rod 3 is movably inserted into the cylinder 2, and the piston 4 is movably inserted into the cylinder 2 and connected to the rod 3, dividing the cylinder 2 into a rod-side chamber 5 and a piston-side chamber 6; a reservoir 7; an actuator circuit A, which has a pump 14, a control channel 40, and a thrust adjustment unit FT, and can drive the telescopic unit 1 to extend and retract. The pump 14 can supply hydraulic oil (liquid) from the reservoir 7 to the cylinder 2. The control channel 40 connects the rod-side chamber 5 to the reservoir 7, and the thrust adjustment unit FT is provided on the control channel 40; an extension-side damping channel 24, which connects the rod-side chamber 5 to the piston-side chamber 6; and an extension-side damping channel 24. Pressure reducing valve 25, the extension-side pressure reducing valve 25 is disposed on the extension-side damping channel 24, and applies resistance to the flow of hydraulic oil (liquid) from the rod-side chamber 5 to the piston-side chamber 6; compression-side damping channel 26, the compression-side damping channel 26 connects the piston-side chamber 6 to the thrust adjustment unit FT; 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 is disposed on the compression-side damping channel 26, and applies resistance to the flow of hydraulic oil (liquid) from the piston-side chamber 6 to the reservoir 7; suction channel 28, the suction channel 28 connects the reservoir 7 to the piston-side chamber 6; shock absorber circuit D, the shock absorber circuit D includes suction check valve 29, the suction check valve 29 is disposed on the suction channel 28, and allows the flow of hydraulic oil (liquid) from the reservoir 7 to the piston-side chamber 6.

[0079] The cylinder device C configured in this embodiment can be used as an actuator by supplying hydraulic oil (liquid) from pump 14 to cylinder 2 via actuator circuit A, and can be used as a damper by stopping pump 14 via damper circuit D.

[0080] Furthermore, when the cylinder device C of this embodiment is used as a shock absorber, if the telescopic unit 1 performs an extension action, a damping force can be generated using the extension-side pressure reducing valve 25; if the telescopic unit 1 performs a retraction action, a damping force can be generated using the first compression-side pressure reducing valve (compression-side pressure reducing valve) 27. Therefore, when the cylinder device C of this embodiment is used as a shock absorber, regardless of the settings of the diameter of the rod 3 and the diameter of the piston 4 (the diameter of the cylinder 2), the damping force characteristics during the extension action and the damping force characteristics during the retraction action can be set to be the same by using the settings of the extension-side pressure reducing valve 25 and the first compression-side pressure reducing valve (compression-side pressure reducing valve) 27.

[0081] That is, in the cylinder device C of this embodiment, even if the diameter of the rod 3 is reduced instead of the diameter of the cylinder 2 within the strength allowable range, the damping force characteristics during the extension action and the damping force characteristics during the retraction action can be set to be the same when used as a shock absorber. As long as the diameter of the rod 3 is reduced instead of the diameter of the cylinder 2 within the strength allowable range, the pressure area of ​​the piston 4 can be increased, and the oil column rigidity (liquid column rigidity) of the hydraulic oil (liquid) in the telescopic unit 1 can be improved. Therefore, when the cylinder device C of this embodiment is used as a shock absorber with an increased damping coefficient, it can generate a high damping force with good responsiveness. Therefore, according to the cylinder device C of this embodiment, it can function as an actuator without increasing the diameter, and the damping coefficient can be improved when used as a shock absorber.

[0082] Furthermore, in the cylinder device C of the first embodiment, the thrust adjustment unit FT includes: an adjustment channel P1 and a bypass channel P2, which are arranged in parallel in the middle of the control channel 40; a variable pressure reducing valve 41, which is arranged on the adjustment channel P1; a pressure reducing valve 43 and a bypass channel switching valve 44, which are arranged in series from the rod-side chamber 5 side on the bypass channel P2; and a compression-side damping channel 26 connecting the piston-side chamber 6 to the bypass channel P2. Between the pressure reducing valve 43 and the bypass channel switching valve 44, the variable pressure reducing valve 41 and the bypass channel switching valve 44 are solenoid valves driven by the same solenoid Sol. The variable pressure reducing valve 41 can adjust the valve opening pressure when the solenoid Sol is energized. The bypass channel switching valve 44 is closed when the solenoid Sol is energized and opened when the solenoid Sol is not energized. When the pump 14 is in actuator mode, the bypass channel switching valve 44 is closed to cut off the bypass channel P2. When the pump 14 is in damper mode, the bypass channel switching valve 44 is opened to open the bypass channel P2.

[0083] The cylinder device C configured in this embodiment can supply hydraulic oil (liquid) from pump 14 to cylinder 2 using actuator circuit A, cut off compression-side damping channel 26 using bypass channel switching valve 44 as an actuator, and stop pump 14 to open compression-side damping channel 26 using bypass channel switching valve 44, using shock absorber circuit D as a shock absorber.

[0084] Furthermore, when the cylinder device C of this embodiment is used as a shock absorber, if the telescopic unit 1 performs an extension action, a damping force can be generated using the extension-side pressure reducing valve 25; if the telescopic unit 1 performs a retraction action, a damping force can be generated using the first compression-side pressure reducing valve (compression-side pressure reducing valve) 27. Therefore, when the cylinder device C of this embodiment is used as a shock absorber, regardless of the settings of the diameter of the rod 3 and the diameter of the piston 4 (the diameter of the cylinder 2), the damping force characteristics during the extension action and the damping force characteristics during the retraction action can be set to be the same by using the settings of the extension-side pressure reducing valve 25 and the first compression-side pressure reducing valve (compression-side pressure reducing valve) 27.

[0085] That is, in the cylinder device C of this embodiment, even if the diameter of the rod 3 is reduced instead of the diameter of the cylinder 2 within the strength allowable range, the damping force characteristics during the extension action and the damping force characteristics during the retraction action can be set to be the same when used as a shock absorber. As long as the diameter of the rod 3 is reduced instead of the diameter of the cylinder 2 within the strength allowable range, the pressure area of ​​the piston 4 can be increased, and the oil column rigidity (liquid column rigidity) of the hydraulic oil (liquid) in the telescopic unit 1 can be improved. Therefore, when the cylinder device C of this embodiment is used as a shock absorber with an increased damping coefficient, it can generate a high damping force with good responsiveness. Therefore, according to the cylinder device C of this embodiment, it can function as an actuator without increasing the diameter, and the damping coefficient can be improved when used as a shock absorber. Furthermore, as shown in the unidirectional flow damper, even if the cross-sectional area of ​​the rod 3 is set to half the cross-sectional area of ​​the piston 4, as long as the compression-side channel 32 and the second compression-side pressure-reducing valve 33 are provided, 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 contracts. Therefore, the damping coefficient during the contraction action can be set higher than that of conventional cylinder devices. Thus, if the compression-side channel 32 and the second compression-side pressure-reducing valve 33 are provided, the degree of freedom in setting the cross-sectional areas of the rod 3 and the piston 4 is increased.

[0086] Furthermore, in the cylinder device C of this embodiment, if the motor 15 and solenoid valves 11, 13, 41, 44 of the cylinder device C are not energized, the bypass channel switch valve 44 automatically connects the compression-side damping channel 26, and the cylinder device C switches to shock absorber mode. Therefore, according to the cylinder device C of this embodiment, the shock absorber circuit D is automatically activated and switched to shock absorber mode when the vehicle is in distress, thus suppressing the vibration of the railway vehicle T's body S even when it is in distress.

[0087] Furthermore, in the cylinder device C of this embodiment, the shock absorber circuit D includes: an extension-side intake channel 30, which connects the reservoir 7 to the rod-side chamber 5; and an extension-side check valve 31, which is installed on the extension-side intake channel 30 and allows only hydraulic oil (liquid) from the reservoir 7 to the rod-side chamber 5 to flow. With this cylinder device C configuration, when the telescopic unit 1 performs a retraction action, no negative pressure is formed in the rod-side chamber 5, and there is no aeration or damping force lag during the transition of the telescopic unit 1 from retraction to extension.

[0088] Furthermore, in the cylinder device C of this embodiment, the actuator circuit A has an adjustable opening pressure and includes a variable pressure reducing valve 41 that allows adjustment of the hydraulic oil (liquid) pressure supplied from the pump 14 to the cylinder 2 by adjusting the opening pressure. The opening pressure of the extension-side pressure reducing valve 25 is higher than the maximum opening pressure selectable by the variable pressure reducing valve 41 in actuator mode. In this cylinder device C, when used as an actuator, the hydraulic oil (liquid) supplied from the pump 14 to the cylinder 2 will not escape from the rod-side chamber 5 to the piston-side chamber 6, thus efficiently generating contraction-side thrust and reducing energy consumption.

[0089] <Second Implementation Method>

[0090] like Figure 3 As shown, the cylinder device C1 in the second embodiment includes and is composed of the following parts: a telescopic unit 1, a liquid reservoir 7, an actuator circuit A1, and a shock absorber circuit D1. In this embodiment, two cylinder devices C1 are installed in parallel between the body S and the trolley B of the railway vehicle T, just like cylinder device C, to suppress the horizontal vibration of the body S. However, it is also possible to install only one cylinder device C1 between the body S and the trolley B.

[0091] The following will describe each part of the cylinder assembly C1. The telescopic unit 1 of the cylinder assembly C1 has the same structure as the telescopic unit 1 of the cylinder assembly C.

[0092] Actuator circuit A1 is a circuit equipped with a pump 14 to drive the telescopic unit 1 to extend and retract. The pump 14 is located 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, actuator circuit A1 supplies hydraulic oil to the cylinder 2, selects one of the extension or retraction directions, and causes the telescopic unit 1 to generate thrust in the selected direction, and the thrust can be adjusted.

[0093] Specifically, such as Figure 3As shown, actuator circuit A includes: a pump 14 disposed between cylinder 2 and reservoir 7, supplying hydraulic oil to rod-side chamber 5; a motor 15 driving pump 14; a control channel 40 connecting rod-side chamber 5 and reservoir 7; a thrust adjustment unit FT1 disposed on control channel 40; a first channel 10 connecting rod-side chamber 5 and piston-side chamber 6; a first switching valve 11 disposed on first channel 10; a second channel 12 connecting piston-side chamber 6 and reservoir 7; and a second switching valve 13 disposed on second channel 12.

[0094] The actuator circuit A1 of the cylinder device C1 in the second embodiment is the same as the actuator circuit A of the cylinder device C in the first embodiment, except that the configuration of the thrust adjustment part FT1 is different.

[0095] In the cylinder device C1 of the second embodiment, the rod-side chamber 5 is connected to the liquid storage tank 7 via a control channel 40, and the thrust adjustment unit FT1 is located in the middle of the control channel 40. The thrust adjustment unit FT1 includes: an adjustment channel P3 located in the middle of the control channel 40; a pressure reducing valve 46 that opens after the pressure on the rod-side chamber 5 reaches the opening pressure; and a variable pressure reducing valve 47 that can adjust the opening pressure by energizing it. The pressure reducing valve 46 and the variable pressure reducing valve 47 are sequentially connected in series on the adjustment channel P3 from the rod-side chamber 5.

[0096] The pressure reducing valve 46 comprises the following parts: a valve body 46a, which is disposed on the adjustment channel P3; a spring 46b, which applies force to the valve body 46a to cut off the adjustment channel P3; and a pilot channel 46c, which applies pressure from the upstream side of the valve body 46a, i.e., the rod-side chamber 5, to the valve body 46a, causing it to exert a force against the spring 46b in the valve opening direction. The opening pressure of the pressure reducing valve 46 is set to a predetermined opening pressure based on the force exerted by the spring 46b on the valve body 46a.

[0097] The variable pressure reducing valve 47 comprises the following parts: a valve body 47a, which is disposed on the adjustment channel P3; a spring 47b, which applies force to the valve body 47a to cut off the adjustment channel P3; a pilot channel 47c, which applies pressure from the upstream side of the valve body 47a, i.e., the rod-side chamber 5, to the valve body 47a, causing it to exert a force against the spring 47b in the valve opening direction; and a solenoid 47d, which generates a thrust against the spring 47b when energized. The variable pressure reducing valve 47 is a solenoid valve, and the valve opening pressure can be adjusted by regulating the amount of current flowing through the solenoid 47d.

[0098] Furthermore, if the pressure upstream of the variable pressure reducing valve 47 and downstream of the pressure reducing valve 46 acting on the adjustment channel P3 of the valve body 47a exceeds the pressure reducing pressure (opening pressure) of the variable pressure reducing valve 47, then the pressure and the force of the solenoid 47d pushing the valve body 47a overcome the force of the spring 47b on the valve body 47a, the valve body 47a retracts, and the variable pressure reducing valve 47 opens the adjustment channel P3.

[0099] Furthermore, for the variable pressure reducing valve 47, increasing the current supplied to the solenoid 47d increases the thrust generated by the solenoid 47d. Therefore, if the current supplied to the solenoid 47d is adjusted to the maximum, the opening pressure of the variable pressure reducing valve 47 becomes the minimum; conversely, if no current is supplied to the solenoid 47d at all, the opening pressure of the variable pressure reducing valve 47 becomes the maximum.

[0100] Next, the shock absorber circuit D1 includes: an extension-side damping channel 24, which connects the rod-side chamber 5 and the piston-side chamber 6; an extension-side pressure-reducing valve 25, which is disposed on the extension-side damping channel 24 and applies resistance to the flow of hydraulic oil from the rod-side chamber 5 to the piston-side chamber 6; a compression-side damping channel 26, which connects the piston-side chamber 6 to the thrust adjustment unit FT1; a first compression-side pressure-reducing valve 27, which acts as a compression-side pressure-reducing valve and is disposed on the compression-side damping channel 26 to apply resistance to the flow of hydraulic oil from the piston-side chamber 6 to the reservoir 7; and a suction channel 28, which connects the reservoir 7 to the reservoir 7. The system includes: a piston-side chamber 6; a suction check valve 29, which is located on the suction channel 28 and allows hydraulic oil to flow from the reservoir 7 to the piston-side chamber 6; an extension-side suction channel 30, which connects the reservoir 7 to the rod-side chamber 5; an extension-side check valve 31, which is located on the extension-side suction channel 30 and only allows hydraulic oil to flow from the reservoir 7 to the rod-side chamber 5; a compression-side channel 32, which connects the piston-side chamber 6 to the rod-side chamber 5; and a second compression-side pressure-reducing valve 33, which is located on the compression-side channel 32 and applies resistance to the flow of hydraulic oil from the piston-side chamber 6 to the rod-side chamber 5.

[0101] The damper circuit D1 of the cylinder device C1 in the second embodiment differs from the damper circuit D of the cylinder device C in the first embodiment in that the pressure reducing valve 46 and the variable pressure reducing valve 47 of the adjustment channel P3 of the thrust adjustment unit FT1 are connected in the compression-side damping channel 26. Otherwise, they have the same configuration.

[0102] In addition, as mentioned above, the compression-side damping channel 26 is connected to the thrust adjustment unit FT1. However, unlike the cylinder device C in the first embodiment, no switching valve is provided on the adjustment channel P3 of the thrust adjustment unit FT1, so the connection between the compression-side damping channel 26 and the liquid storage tank 7 will not be cut off.

[0103] The cylinder assembly C1 is configured as described above. The operation of the cylinder assembly C1 will now be explained. First, the actuator mode, in which the cylinder assembly C1 is used as an actuator via actuator circuit A1, will be explained. When the cylinder assembly C1 generates thrust in the extension direction, the first switching valve 11 is adjusted to the connected position 11b, and the second switching valve 13 is adjusted to the cut-off position 13c. The pump 14 is driven by the motor 15 to supply hydraulic oil from the reservoir 7 to the cylinder 2. Furthermore, the current supplied to the solenoid 47d is adjusted, and the opening pressure of the variable pressure reducing valve 47 is adjusted according to the thrust required by the cylinder assembly C1.

[0104] Thus, after the first switching valve 11 is opened, the rod-side chamber 5 and the piston-side chamber 6 are connected through the first channel 10, and hydraulic oil is supplied from the pump 14 to the rod-side chamber 5 and the piston-side chamber 6.

[0105] Therefore, if the first switching valve 11 is adjusted to the connected position 11b and the second switching valve 13 is adjusted to the cut-off position 13c, and the pump 14 is driven by the motor 15, the hydraulic oil supplied from the pump 14 to the cylinder 2 will push the piston 4 relative to the cylinder 2. Figure 1 The left side pushes, so the cylinder device C1 generates a thrust in the extension direction.

[0106] In the cylinder device C1 of the second embodiment, the compression-side damping channel 26 is not cut off by the switching valve. Therefore, the hydraulic oil supplied to the cylinder 2 can move from the rod-side chamber 5 to the reservoir 7 via the control channel 40 and the thrust adjustment unit FT1, and from the piston-side chamber 6 to the reservoir 7 via the compression-side damping channel 26, the first compression-side pressure reducing valve 27, and the thrust adjustment unit FT1.

[0107] Furthermore, both the pressure inside the rod-side chamber 5 and the pressure inside the piston-side chamber 6, which is connected to the rod-side chamber 5 via the first channel 10, exceed the opening pressure of the pressure reducing valve 46 and the first compression-side pressure reducing valve 27. If the variable pressure reducing valve 47 is opened, the hydraulic oil in the rod-side chamber 5 moves to the reservoir 7 via the control channel 40 and the adjustment channel P3, and the hydraulic oil in the piston-side chamber 6 moves to the reservoir 7 via the compression-side damping channel 26 and the adjustment channel P3.

[0108] That is, when the first switch valve 11 is adjusted to the connected position 11b and the second switch valve 13 is adjusted to the cut-off position 13c, the following circuit configuration is formed: a pressure reducing valve 46 and a first compression-side pressure reducing valve 27 are connected in parallel between the cylinder 2 and the liquid storage tank 7, and a variable pressure reducing valve 47 is configured downstream of these pressure reducing valves 46 and the first compression-side pressure reducing valve 27.

[0109] When the first switching valve 11 is adjusted to the connected position 11b and the second switching valve 13 is adjusted to the cut-off position 13c, if hydraulic oil is supplied from the pump 14 into the cylinder 2, and there is excess hydraulic oil in the cylinder 2, the hydraulic oil pushed out of the cylinder 2 will pass through one or both of the pressure reducing valve 46 and the first compression-side pressure reducing valve 27, and will definitely move to the reservoir 7 through the variable pressure reducing valve 47. Therefore, the pressure inside the cylinder 2 can be adjusted by adjusting the opening pressure of the variable pressure reducing valve 47. Thus, in the cylinder device C1 of the second embodiment, when the first switching valve 11 is adjusted to the connected position 11b and the second switching valve 13 is adjusted to the cut-off 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 inside the cylinder 2 increases, and the cylinder device C1 generates a thrust in the extension direction.

[0110] In summary, when the cylinder device C1 of the second embodiment adjusts the first switching valve 11 to the connected position 11b and the second switching valve 13 to the cut-off position 13c, it generates a thrust in the extension direction, similar to the cylinder device C. The value of this thrust is the difference in pressure area between the piston-side chamber and the rod-side chamber of the piston 4 multiplied by the pressure in the rod-side chamber 5. This thrust can be adjusted by regulating the opening pressure of the variable pressure reducing valve 47. Furthermore, in this state, even if the telescopic unit 1 is forced to contract by an external force, the pressure in the rod-side chamber 5 and the piston-side chamber 6 can be controlled using the variable pressure reducing valve 47, generating a thrust in the extension direction that suppresses contraction.

[0111] In addition, during the process of the cylinder device C1 generating the thrust in the extension direction, the telescopic unit 1 is subjected to external force and contracts at high speed. When the piston-side chamber 6 is under abnormally high pressure, the second compression-side pressure reducing valve 33 opens, causing the hydraulic oil in the piston-side chamber 6 to move to the rod-side chamber 5, so the cylinder device C1 is protected.

[0112] In contrast, when the cylinder assembly C1 generates a thrust in the contraction direction, the first switching valve 11 is adjusted to the cut-off position 11c, and the second switching valve 13 is adjusted to the open position 13b. The pump 14 is driven by the motor 15 to supply hydraulic oil from the reservoir 7 to the rod-side chamber 5. In addition, the current supplied to the solenoid 47d is adjusted, and the opening pressure of the variable pressure reducing valve 47 is adjusted according to the thrust required by the cylinder assembly C1.

[0113] Thus, when the second switching valve 13 opens, the piston-side chamber 6 and the reservoir 7 are connected through the second channel 12. The first switching valve 11 closes, cutting off the connection between the rod-side chamber 5 and the piston-side chamber 6. Therefore, the hydraulic oil injected by the pump 14 is only supplied to the rod-side chamber 5. Furthermore, in the cylinder assembly C1, the compression-side damping channel 26 is not cut off by the switching valve. However, when the piston-side chamber 6 and the reservoir 7 are connected through the second channel 12, if the cylinder assembly C1 contracts, the hydraulic oil only moves from the piston-side chamber 6 to the reservoir 7 through the second channel 12.

[0114] Therefore, if the first switching valve 11 is adjusted to the cut-off position 11c and the second switching valve 13 is adjusted to the connected 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 will push the piston 4 relative to the cylinder 2. Figure 1 The right-hand side pushes, so the cylinder device C1 generates a thrust in the contraction direction.

[0115] In the cylinder device C1 of the second embodiment, if the first switching valve 11 is adjusted to the cut-off position 11c and the second switching valve 13 is adjusted to the connected position 13b, and the pump 14 is driven by the motor 15, then only hydraulic oil is supplied to the rod-side chamber 5. If there is excess hydraulic oil in the rod-side chamber 5, 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. Therefore, the pressure inside the cylinder 2 can be adjusted by adjusting the opening pressure of the variable pressure reducing valve 47. Thus, in the cylinder device C1 of the second embodiment, when the first switching valve 11 is adjusted to the cut-off position 11c and the second switching valve 13 is adjusted to the connected position 13b, the pressure reducing valve 46 and the variable pressure reducing valve 47 create resistance, the pressure inside the cylinder 2 increases, and the cylinder device C1 generates a thrust in the contraction direction.

[0116] In summary, when the cylinder device C1 of the second embodiment adjusts the first switching valve 11 to the cut-off position 11c and the second switching valve 13 to the connected position 13b, it generates a contraction thrust, similar to the cylinder device C. The value of this thrust is equal to the product of the pressure area on the rod-side chamber side of the piston 4 multiplied by the opening pressure of the variable pressure reducing valve 47, minus the product of the pressure area on the piston-side chamber side of the piston 4 multiplied by the pressure of the reservoir 7. Furthermore, the thrust can be adjusted by regulating the opening pressure of the variable pressure reducing valve 47. In this state, even if the telescopic unit 1 is forced to extend by an external force, the pressure inside the rod-side chamber 5 can be controlled using the variable pressure reducing valve 47, thus generating a contraction thrust that inhibits extension.

[0117] Furthermore, as mentioned above, when the cylinder device C1 of this embodiment generates a thrust in the contraction direction, hydraulic oil needs to be supplied to the rod-side chamber 5 while the communication between the rod-side chamber 5 and the piston-side chamber 6 is cut off. Here, if the extension-side pressure relief valve 25 is opened, the extension-side damping channel 24 of the shock absorber circuit D1 allows hydraulic oil to flow from the rod-side chamber 5 to the piston-side chamber 6.

[0118] Therefore, when the cylinder device C1 of this embodiment generates thrust in the contraction direction, if the extension-side pressure reducing valve 25 opens, hydraulic oil escapes from the rod-side chamber 5 to the piston-side chamber 6, thus reducing efficiency. However, the opening pressure of the extension-side pressure reducing valve 25 is set to be greater than or equal to the difference between the pressure in the rod-side chamber 5 and the pressure in the piston-side chamber 6 when the telescopic unit 1 generates maximum thrust in the contraction direction using the actuator circuit A1. The maximum thrust in the contraction direction of the cylinder device C1 in actuator mode is generated when the variable pressure reducing valve 47 sets the opening pressure to the maximum. Therefore, when the cylinder device C1 of this embodiment is used as an actuator to generate thrust in the contraction direction, even if the opening pressure of the variable pressure reducing valve 47 is set to the maximum, the extension-side pressure reducing valve 25 will not open, preventing hydraulic oil from moving from the rod-side chamber 5 to the piston-side chamber 6 through the extension-side damping channel 24. Thus, if the opening pressure of the extension-side pressure reducing valve 25 is set to be greater than or equal to the difference between the pressure in the rod-side chamber 5 and the pressure in the piston-side chamber 6 when the telescopic unit 1 generates maximum thrust towards the contraction side using the actuator circuit A1, then the cylinder device C1 can efficiently generate thrust in the contraction direction when used as an actuator, with less energy consumption. As mentioned above, in the cylinder device C1 of this embodiment, even if the variable pressure reducing valve 47, which controls the pressure in the rod-side chamber 5, sets its opening pressure to the maximum, as long as the extension-side pressure reducing valve 25 does not open, the opening pressure of the extension-side pressure reducing valve 25 only needs to be higher than the pressure loss generated by the pressure reducing valve 46 and the variable pressure reducing valve 47 when the variable pressure reducing valve 47 is set to the maximum opening pressure, that is, higher than the pressure loss generated by the thrust adjustment unit FT1. In this case, the opening pressure of the extension-side pressure reducing valve 25 is not the maximum pressure loss in terms of the thrust adjustment unit FT1 hardware, and can be higher than the maximum pressure loss selectable in terms of the thrust adjustment unit FT1 control in actuator mode.

[0119] In addition, as mentioned above, from the point of view of efficiency, the opening pressure of the extension side pressure reducing valve 25 can be set to be greater than or equal to the difference between the pressure in the rod side chamber 5 and the pressure in the piston side chamber 6 when the telescopic unit 1 generates the maximum thrust to the contraction side using the actuator circuit A1. However, even if the opening pressure is set to be less than the difference, the cylinder device C1 can still be used as an actuator to generate thrust in the contraction direction.

[0120] During the process of the cylinder device C1 generating a thrust in the contraction direction, the telescopic unit 1 is subjected to external force and extends at high speed. When there is abnormal high pressure in the rod side chamber 5, the extension side pressure reducing valve 25 opens, causing the hydraulic oil in the rod side chamber 5 to move to the piston side chamber 6, so the cylinder device C1 is protected.

[0121] Thus, the cylinder assembly C1 can generate thrust in any direction within the adjustable range, either in the extension or contraction direction, by switching the first switching valve 11 and the second switching valve 13 and adjusting the opening pressure of the variable pressure reducing valve 47. Therefore, in actuator mode, the cylinder assembly C1 can be used as an actuator to suppress vibrations of the vehicle body S by driving the pump 14 and controlling the first switching valve 11, the second switching valve 13, and the variable pressure reducing valve 47.

[0122] Next, the damper mode of using cylinder assembly C as a damper using damper circuit D1 will be explained. When cylinder assembly C1 is switched to damper mode, the first switching valve 11 is switched to the off position 11c, the second switching valve 13 is switched to the off position 13c, the motor 15 is not driven, and the pump 14 is stopped. In addition, the solenoid 47d can be energized or de-energized.

[0123] In this state, the connection between the rod-side chamber 5 and the piston-side chamber 6 via the first channel 10 is cut off, and the connection between the piston-side chamber 6 and the reservoir 7 via the second channel 12 is also cut off. Thus, when the cylinder assembly C1 is used as the damper mode of the shock absorber, the compression-side damping channel 26 is also connected to the reservoir 7 via the variable pressure relief valve 47 of the thrust adjustment unit FT1.

[0124] Furthermore, when the cylinder assembly C1 is in shock absorber mode, if the telescopic unit 1 is extended by an external force, the piston 4 will move relative to the cylinder 2. Figure 1The telescopic unit 1 moves to the left, shrinking the rod-side chamber 5 and expanding the piston-side chamber 6. The hydraulic oil in the shrunken rod-side chamber 5 is resisted by one or both of the thrust adjustment unit FT1 and the extension-side pressure reducing valve 25 of the extension-side damping channel 24, and moves to the reservoir 7 or the expanded piston-side chamber 6. When the telescopic unit 1 performs the extension action, the rod 3 retracts from the cylinder 2, resulting in insufficient hydraulic oil in the cylinder 2. However, after the suction check valve 29 opens, the insufficient hydraulic oil is supplied from the reservoir 7 to the piston-side chamber 6 through the suction channel 28. Thus, if the cylinder device C1 enters the damper mode and the telescopic unit 1 performs the extension action, the pressure in the rod-side chamber 5 increases due to the thrust adjustment unit FT1 and the extension-side pressure reducing valve 25, and the pressure in the piston-side chamber 6 becomes equal to the pressure in the reservoir. Therefore, the cylinder device C1 generates a damping force in the direction that hinders the extension of the telescopic unit 1. The value of this force is equal to the product of the pressure area on the rod side chamber of piston 4 multiplied by the pressure inside the rod side chamber 5, minus the product of the pressure area on the piston side chamber of piston 4 multiplied by the pressure in the liquid storage tank 7.

[0125] Furthermore, when the cylinder assembly C1 is in shock absorber mode, if the telescopic unit 1 is contracted by an external force, the piston 4 will move relative to the cylinder 2. Figure 1The telescopic unit 1 moves to the right, shrinking the piston-side chamber 6 and expanding the rod-side chamber 5. Hydraulic oil in the shrunken piston-side chamber 6 moves to the expanded rod-side chamber 5 through the second compression-side pressure-reducing valve 33 in the compression-side channel 32. When the telescopic unit 1 retracts, the rod 3 enters the cylinder 2, resulting in excess hydraulic oil in the cylinder 2. However, after the first compression-side pressure-reducing valve 27 and the variable pressure-reducing valve 47 open, the excess hydraulic oil is discharged from the piston-side chamber 6 to the reservoir 7 through the compression-side damping channel 26, the adjustment channel P3, and the control channel 40. Thus, if the cylinder device C1 enters the damper mode and the telescopic unit 1 retracts, 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, while the pressure in the rod-side chamber 5 decreases, making the pressure in the piston-side chamber 6 higher than that in the rod-side chamber 5. Therefore, the cylinder device C1 generates a damping force in the direction that hinders the contraction of the telescopic unit 1. The value of this force is equal to the product of the piston-side chamber pressure area of ​​piston 4 multiplied by the pressure inside piston-side chamber 6, minus the product of the rod-side chamber pressure area of ​​piston 4 multiplied by the pressure inside rod-side chamber 5. Furthermore, in this embodiment, the cylinder device C1 includes an extension-side intake channel 30 and an extension-side check valve 31. Therefore, when the telescopic unit 1 of the cylinder device C1 in shock absorber mode contracts, if the pressure inside rod-side chamber 5 is lower than the pressure in the reservoir, the extension-side check valve 31 opens, and hydraulic oil is supplied from the reservoir 7 to rod-side chamber 5. Thus, when the cylinder device C1 in this embodiment contracts in shock absorber mode, a negative pressure does not form inside rod-side chamber 5, and there is no aeration or lag in damping force generation during the transition of the telescopic unit 1 from contraction to extension.

[0126] Thus, in shock absorber mode, if the telescopic unit 1 is subjected to an external force and extends or retracts, the cylinder device C1 generates a damping force that hinders the extension or retraction of the telescopic unit 1. Moreover, in shock absorber mode, the cylinder device C1 generates a damping force using one or both of the thrust adjustment unit FT1 and the extension-side pressure reducing valve 25 when the telescopic unit 1 extends, and generates a damping force using 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 telescopic unit 1 retracts. Therefore, the damping force characteristics of the piston speed generated when the shock absorber mode cylinder device C1 performs the extension action are set using the pressure reducing valve 46 and variable pressure reducing valve 47 of the thrust adjustment unit FT1 and the extension side pressure reducing valve 25. The damping force characteristics of the piston speed generated when the shock absorber mode cylinder device C1 performs the contraction action are set using the first compression side pressure reducing valve 27 and variable pressure reducing valve 47 and second compression side pressure reducing valve 33. Therefore, the damping force characteristics when performing the extension action and when performing the contraction action can be set independently.

[0127] That is, regardless of the settings of the pressure-bearing area on the rod side and the pressure-bearing area on the piston side of piston 4, the damping force characteristics of the cylinder device C in this embodiment of the shock absorber mode during both the extension and contraction actions can be independently adjusted using 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. In other words, when the two damping force characteristics of the cylinder device C1 in this embodiment of the shock absorber mode during both the extension and contraction actions are set to be the same, it is not necessary to set the cross-sectional area of ​​the rod 3 to half the cross-sectional area of ​​the piston 4. After arbitrarily determining the diameters of the rod 3 and the piston 4 (the diameter of the cylinder 2) within the strength allowable range, it is only necessary to adjust the two damping force characteristics to be the same using 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.

[0128] Furthermore, the shock absorber circuit D1 in this embodiment includes an extension-side intake channel 30 and an extension-side check valve 31. When the telescopic unit 1 of the shock absorber-mode cylinder device C1 performs a retraction action, hydraulic oil is allowed to flow from the reservoir 7 to the enlarged rod-side chamber 5, so the compression-side channel 32 and the second compression-side pressure-reducing valve 33 can be omitted. In this case, by setting the pressure-reducing valve 46, the variable pressure-reducing valve 47, the extension-side pressure-reducing valve 25, and the first compression-side pressure-reducing valve 27, the two damping force characteristics of the cylinder device C1 in this embodiment of the shock absorber mode when performing the extension action and when performing the retraction action can be adjusted to be the same.

[0129] However, when the compression side passage 32 and the second compression side pressure reducing valve 33 are provided, the following advantages are available: when the telescopic unit 1 of the shock absorber mode cylinder device C1 performs the retraction action, if the pressure in the piston side chamber 6 is abnormally high, the second compression side pressure reducing valve 33 will open, allowing the hydraulic oil in the piston side chamber 6 to move to the rod side chamber 5, which can protect the cylinder device C1.

[0130] Furthermore, the shock absorber circuit D1 of this embodiment includes a compression side channel 32 and a second compression side pressure reducing valve 33. Therefore, when the telescopic unit 1 of the shock absorber mode cylinder device C1 performs a retraction action, 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 channel 32 will cause negative pressure to form in the rod side chamber 5, the extension side suction channel 30 and the extension side check valve 31 can be omitted.

[0131] Furthermore, a check valve that does not exert too much resistance on the passing hydraulic oil is installed on the compression side channel 32 instead of the second compression side pressure reducing valve 33. When the telescopic unit 1 of the shock absorber mode cylinder device C1 performs a retraction action, the resistance of the first compression side pressure reducing valve 27 and the variable pressure reducing valve 47 can be used to generate a damping force. In this case, the damping force characteristics relative to the piston speed generated when the shock absorber mode cylinder device C1 performs an extension action can be set using the extension side pressure reducing valve 25, the pressure reducing valve 46, and the variable pressure reducing valve 47, and the damping force characteristics relative to the piston speed generated when the shock absorber mode cylinder device C1 performs a retraction action can be set using the first compression side pressure reducing valve 27 and the variable pressure reducing valve 47. Therefore, regardless of the setting of the pressure-bearing area on the rod side chamber side of the piston 4 and the pressure-bearing area on the piston side chamber side, the damping force characteristics of the shock absorber mode cylinder device C1 when performing an extension action and when performing a retraction action can be set to the same characteristics.

[0132] In summary, the cylinder device C1 of this embodiment includes: a telescopic unit 1, which has a cylinder 2, a rod 3, and a piston 4. The rod 3 is movably inserted into the cylinder 2, and the piston 4 is movably inserted into the cylinder 2 and connected to the rod 3, dividing the cylinder 2 into a rod-side chamber 5 and a piston-side chamber 6; a reservoir 7; an actuator circuit A1, which has a pump 14, a control channel 40, and a thrust adjustment unit FT1, and can drive the telescopic unit 1 to extend or retract. The pump 14 can supply hydraulic oil (liquid) from the reservoir 7 to the cylinder 2. The control channel 40 connects the rod-side chamber 5 to the reservoir 7, and the thrust adjustment unit FT1 is provided on the control channel 40; an extension-side damping channel 24, which connects the rod-side chamber 5 to the piston-side chamber 6; and an extension... The system includes: a side pressure relief valve 25, which is disposed on the extension side damping channel 24 and applies resistance to the flow of hydraulic oil (liquid) from the rod side chamber 5 to the piston side chamber 6; a compression side damping channel 26, which connects the piston side chamber 6 to the thrust adjustment unit FT1; a first compression side pressure relief valve 27, which is disposed on the compression side damping channel 26 and applies resistance to the flow of hydraulic oil (liquid) from the piston side chamber 6 to the reservoir 7; a suction channel 28, which connects the reservoir 7 to the piston side chamber 6; and a shock absorber circuit D1, which includes a suction check valve 29, which is disposed on the suction channel 28 and allows the flow of hydraulic oil (liquid) from the reservoir 7 to the piston side chamber 6.

[0133] The cylinder device C1 configured in this embodiment can be used as an actuator by supplying hydraulic oil (liquid) from pump 14 to cylinder 2 via actuator circuit A1, and can be used as a damper by stopping pump 14 via damper circuit D1.

[0134] Furthermore, when the cylinder device C1 of this embodiment is used as a shock absorber, if the telescopic unit 1 performs an extension action, a damping force can be generated using the extension-side pressure reducing valve 25; if the telescopic unit 1 performs a retraction action, a damping force can be generated using the first compression-side pressure reducing valve (compression-side pressure reducing valve) 27. Therefore, when the cylinder device C1 of this embodiment is used as a shock absorber, regardless of the settings of the diameter of the rod 3 and the diameter of the piston 4 (the diameter of the cylinder 2), the damping force characteristics during the extension action and the damping force characteristics during the retraction action can be set to be the same by using the settings of the extension-side pressure reducing valve 25 and the first compression-side pressure reducing valve (compression-side pressure reducing valve) 27.

[0135] That is, in the cylinder device C1 of this embodiment, even if the diameter of the rod 3 is reduced instead of the diameter of the cylinder 2 within the strength allowable range, the damping force characteristics during the extension action and the damping force characteristics during the retraction action can be set to be the same when used as a shock absorber. As long as the diameter of the rod 3 is reduced instead of the diameter of the cylinder 2 within the strength allowable range, the pressure area of ​​the piston 4 can be increased, and the oil column rigidity (liquid column rigidity) of the hydraulic oil (liquid) in the telescopic unit 1 can be improved. Therefore, when the cylinder device C1 of this embodiment is used as a shock absorber with an increased damping coefficient, it can generate a high damping force with good responsiveness. Therefore, according to the cylinder device C1 of this embodiment, it can function as an actuator without increasing the diameter, and the damping coefficient can be improved when used as a shock absorber.

[0136] In the cylinder device C of the first embodiment, the compression-side damping channel 26, which is equipped with a first compression-side pressure reducing valve 27, is connected between the pressure reducing valve 43 and the bypass channel switching valve 44 of the bypass channel P2 of the thrust adjustment unit FT. In actuator mode, the bypass channel switching valve 44 is shut off, thus shutting off the compression-side damping channel 26. However, in the cylinder device C1 of the second embodiment, in actuator mode, the switching valve is not used to shut off the compression-side damping channel 26. Instead, the compression-side damping channel 26 is connected upstream of the variable pressure reducing valve 47 of the thrust adjustment unit 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, in damper mode, both the cylinder device C of the first embodiment and the cylinder device C1 of the second embodiment necessarily utilize the first compression-side pressure reducing valve 27 to generate damping force. Thus, the thrust adjustment units FT and FT1 can be configured to generate damping force using the first compression-side pressure relief valve 27 when in shock absorber mode. In actuator mode, the compression-side damping channel 26, which is equipped with the first compression-side pressure relief valve 27, can be completely cut off as shown in cylinder device C of the first embodiment, or the compression-side damping channel 26 can be kept connected without cutting off, as shown in cylinder device C1 of the second embodiment.

[0137] That is, as shown in the thrust adjustment unit FT1 of the second embodiment, when only one adjustment channel P3 with an adjustable thrust variable pressure reducing valve 47 is provided, it is only necessary to connect the compression-side damping channel 26 upstream of the variable pressure reducing valve 47. Furthermore, as shown in the thrust adjustment unit FT of the first embodiment, when it is provided with an adjustment channel P1 with an adjustable thrust variable pressure reducing valve 41 and a bypass channel switch valve P2 that is open in damper mode, it is only necessary to connect the compression-side damping channel 26 upstream of the bypass channel switch valve 44 of the bypass channel P2 that is activated in damper mode. Moreover, the thrust adjustment unit FT1 can have three or more parallel channels; it is only necessary to connect the compression-side damping channel 26 upstream of the variable pressure reducing valve or switch valve in the channel where the variable pressure reducing valve or switch valve is provided. As described above, the thrust adjustment units FT and FT1 can control the pressure in the upstream cylinder 2 and adjust the thrust of the cylinder devices C and C1 in actuator mode. They only need to have a channel equipped with a variable pressure reducing valve or a switching valve that is in a connected state in shock absorber mode. The compression side damping channel 26 only needs to be connected upstream of the variable pressure reducing valve or the switching valve of the channel that is in a connected state in shock absorber mode.

[0138] Furthermore, in the cylinder device C1 of the second embodiment, the thrust adjustment unit FT1 includes: an adjustment channel P3, which is located in the middle of the control channel 40; a pressure reducing valve 46, which opens after the pressure on the rod-side chamber 5 reaches the opening pressure; and a variable pressure reducing valve 46, which can adjust the opening pressure by energizing it. The pressure reducing valve 46 and the variable pressure reducing valve 47 are sequentially connected in series on the adjustment channel P3 from the rod-side chamber 5. The compression-side damping channel 26 connects the piston-side chamber 6 between the pressure reducing valve 46 and the variable pressure reducing valve 47 in the adjustment channel P3.

[0139] Even if the thrust adjustment unit FT1 does not have a switch valve to cut off the compression-side damping channel 26 in actuator mode, the cylinder device C1 configured in this embodiment can generate compression-side damping force using the first compression-side pressure reducing valve 27 in shock absorber mode. The configuration of the thrust adjustment unit FT1 becomes simple and no switch valve is required, thus reducing the manufacturing cost of the cylinder device C1.

[0140] Furthermore, when the cylinder device C1 of this embodiment is used as a shock absorber, if the telescopic unit 1 performs an extension action, a damping force can be generated using the extension-side pressure reducing valve 25; if the telescopic unit 1 performs a retraction action, a damping force can be generated using the first compression-side pressure reducing valve (compression-side pressure reducing valve) 27. Therefore, when the cylinder device C1 of this embodiment is used as a shock absorber, regardless of the settings of the diameter of the rod 3 and the diameter of the piston 4 (the diameter of the cylinder 2), the damping force characteristics during the extension action and the damping force characteristics during the retraction action can be set to be the same by using the settings of the extension-side pressure reducing valve 25 and the first compression-side pressure reducing valve (compression-side pressure reducing valve) 27.

[0141] That is, in the cylinder device C1 of this embodiment, even if the diameter of the rod 3 is reduced instead of the diameter of the cylinder 2 within the strength allowable range, the damping force characteristics during the extension action and the damping force characteristics during the retraction action can be set to be the same when used as a shock absorber. As long as the diameter of the rod 3 is reduced instead of the diameter of the cylinder 2 within the strength allowable range, the pressure area of ​​the piston 4 can be increased, and the oil column rigidity (liquid column rigidity) of the hydraulic oil (liquid) in the telescopic unit 1 can be improved. Therefore, when the cylinder device C1 of this embodiment is used as a shock absorber with improved damping coefficient, it can generate a high damping force with good responsiveness. Therefore, according to the cylinder device C1 of this embodiment, it can function as an actuator without increasing the diameter, and the damping coefficient can be improved when used as a shock absorber. Furthermore, as shown in the unidirectional flow damper, even if the cross-sectional area of ​​the rod 3 is set to half the cross-sectional area of ​​the piston 4, as long as the compression-side channel 32 and the second compression-side pressure-reducing valve 33 are provided, 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 contracts. Therefore, the damping coefficient during the contraction action can be set higher than that of conventional cylinder devices. Thus, if the compression-side channel 32 and the second compression-side pressure-reducing valve 33 are provided, the degree of freedom in setting the cross-sectional areas of the rod 3 and the piston 4 is increased.

[0142] Furthermore, in the cylinder device C of this embodiment, if the motor 15 and solenoid valves 11, 13, and 47 of the cylinder device C are not energized, the cylinder device C1 automatically switches to the shock absorber mode. Therefore, according to the cylinder device C1 of this embodiment, the shock absorber circuit D1 is automatically activated and switched to the shock absorber mode when the vehicle is stuck, thus suppressing the vibration of the railway vehicle T's body S when it is stuck.

[0143] Furthermore, in the cylinder device C1 of this embodiment, the shock absorber circuit D1 includes: an extension-side intake channel 30, which connects the reservoir 7 to the rod-side chamber 5; and an extension-side check valve 31, which is installed on the extension-side intake channel 30 and allows only hydraulic oil (liquid) from the reservoir 7 to the rod-side chamber 5 to flow. With this cylinder device C1 configuration, when the telescopic unit 1 performs a retraction action, a negative pressure will not form in the rod-side chamber 5, and there will be no aeration or damping force lag during the transition of the telescopic unit 1 from retraction to extension.

[0144] Furthermore, in the cylinder device C1 of this embodiment, the actuator circuit A1 has an adjustable valve opening pressure and a variable pressure reducing valve 47 that allows adjustment of the pressure inside the cylinder 2 by adjusting the valve opening pressure. The opening pressure of the extension-side pressure reducing valve 25 is higher than the maximum pressure loss selectable by the thrust adjustment unit FT1 in actuator mode. In the cylinder device C1 configured in this way, when used as an actuator, the hydraulic oil (liquid) supplied from the pump 14 to the cylinder 2 will not escape from the rod-side chamber 5 to the piston-side chamber 6, so the contraction-side thrust can be generated efficiently and energy consumption is also reduced.

[0145] As shown above, the description of the embodiments of the present invention ends, but the scope of the present invention is of course not limited to the contents of the illustrations or detailed description.

[0146] Symbol Explanation

[0147] 1 Telescopic Unit

[0148] 2 cylinders

[0149] 3 rods

[0150] 4 Pistons

[0151] 5. Rod side chamber

[0152] 6 Piston side chamber

[0153] 7. Liquid Storage Tank

[0154] 14 pumps

[0155] 24 Elongation-side damping channel

[0156] 25 Extended-side pressure reducing valve

[0157] 26 Compression-side damping channel

[0158] 27 First compression-side pressure reducing valve (compression-side pressure reducing valve)

[0159] 28. Inhalation Channel

[0160] 29. Suction check valve

[0161] 30. Extended side inhalation channel

[0162] 31 Extended side check valve

[0163] 40 control channels

[0164] 41,47 Variable pressure reducing valve

[0165] 42 Bypass lane

[0166] 43,46 Pressure reducing valve

[0167] 44 Bypass channel switch valve

[0168] A,A1 Actuator Circuit

[0169] C,C1 cylinder assembly

[0170] D,D1 shock absorber circuit

[0171] FT, FT1 Thrust Adjustment Unit

[0172] P1, P3 Adjust Channels

[0173] P2 Bypass

[0174] Sol solenoid

Claims

1. A cylinder device, comprising: a telescopic unit having a cylinder, a rod member movably inserted into the cylinder, and a piston movably inserted into the cylinder and connected to the rod member to divide the cylinder into a rod member side chamber and a piston side chamber; a liquid tank; an actuator circuit having a pump, an adjustment passage, and a bypass passage, and capable of driving the telescopic unit to extend and retract, the pump being capable of supplying liquid from the liquid tank to the cylinder, the adjustment passage communicating the rod member side chamber with the liquid tank and having a variable pressure reducing valve provided thereon, and the bypass passage communicating the rod member side chamber with the liquid tank and having a pressure reducing valve and a bypass passage on-off valve provided thereon in series; and a damper circuit including an extension side damping passage, an extension side pressure reducing valve, a compression side damping passage, a compression side pressure reducing valve, a suction passage, and a suction check valve, the extension side damping passage communicating the rod member side chamber with the piston side chamber, the extension side pressure reducing valve being provided on the extension side damping passage to exert resistance to liquid flow from the rod member side chamber to the piston side chamber, the compression side damping passage connecting the piston side chamber to the pressure reducing valve and the bypass passage on-off valve of the bypass passage, the compression side pressure reducing valve being provided on the compression side damping passage to exert resistance to liquid flow from the piston side chamber to the liquid tank, and the suction passage communicating the liquid tank with the piston side chamber, the suction check valve being provided on the suction passage to allow liquid flow from the liquid tank to the piston side chamber, the variable pressure reducing valve and the bypass passage on-off valve being solenoid valves driven by the same solenoid, the variable pressure reducing valve being capable of adjusting the opening pressure when the solenoid is energized, the bypass passage on-off valve being closed when the solenoid is energized and opened when the solenoid is not energized, the bypass passage being shut off by closing the bypass passage on-off valve when the actuator mode of driving the pump is selected, and the bypass passage being opened by opening the bypass passage on-off valve when the damper mode of stopping the pump is selected.

2. The cylinder device according to claim 1, wherein the opening pressure of the extension side pressure reducing valve is higher than the maximum opening pressure selectable by the variable pressure reducing valve when the actuator mode is selected.

3. A cylinder device, comprising: a telescopic unit having a cylinder, a rod member movably inserted into the cylinder, and a piston movably inserted into the cylinder and connected to the rod member to divide the cylinder into a rod member side chamber and a piston side chamber; a liquid tank; an actuator circuit having a pump, a control passage, and a thrust adjusting portion, and capable of driving the telescopic unit to extend and retract, the pump being capable of supplying liquid from the liquid tank to the cylinder, the control passage communicating the rod member side chamber with the liquid tank, and the thrust adjusting portion being provided on the control passage; and a damper circuit including an extension side damping passage, an extension side pressure reducing valve, a compression side damping passage, a compression side pressure reducing valve, a suction passage, and a suction check valve, the extension side damping passage communicating the rod member side chamber with the piston side chamber, the extension side pressure reducing valve being provided on the extension side damping passage to exert resistance to liquid flow from the rod member side chamber to the piston side chamber, the compression side damping passage connecting the piston side chamber to the control passage, the compression side pressure reducing valve being provided on the compression side damping passage to exert resistance to liquid flow from the piston side chamber to the liquid tank, and the suction passage communicating the liquid tank with the piston side chamber, the suction check valve being provided on the suction passage to allow liquid flow from the liquid tank to the piston side chamber, the variable pressure reducing valve and the bypass passage on-off valve being solenoid valves driven by the same solenoid, the variable pressure reducing valve being capable of adjusting the opening pressure when the solenoid is energized, the bypass passage on-off valve being closed when the solenoid is energized and opened when the solenoid is not energized, the bypass passage being shut off by closing the bypass passage on-off valve when the actuator mode of driving the pump is selected, and the bypass passage being opened by opening the bypass passage on-off valve when the damper mode of stopping the pump is selected. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ A shock absorber circuit includes an extension-side damping passage that communicates the rod-side chamber and the piston-side chamber, an extension-side pressure-reducing valve that is provided on the extension-side damping passage and exerts 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 adjusting section, a compression-side pressure-reducing valve that is provided on the compression-side damping passage and exerts resistance to liquid flow from the piston-side chamber to the reservoir tank, a suction passage that communicates the reservoir tank and the piston-side chamber, and a suction check valve that is provided on the suction passage and allows liquid flow from the reservoir tank to the piston-side chamber, The thrust adjusting section has an adjusting passage that is provided midway through the control passage, a pressure-reducing valve that opens when the rod-side chamber side pressure reaches an opening pressure, and a variable pressure-reducing valve that can adjust the opening pressure by energization, the pressure-reducing valve and the variable pressure-reducing valve being arranged in series on the adjusting passage from the rod-side chamber side, The compression-side damping passage connects the piston-side chamber to the pressure-reducing valve and the variable pressure-reducing valve of the adjusting passage.

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