Cylinder Device

Abstract

To provide a cylinder device capable of improving a damping coefficient when the cylinder device functions as a damper while exhibiting a function as an actuator without increasing the weight and size.SOLUTION: A cylinder device C includes a telescopic unit 1, a tank 7, and an actuator circuit A and a damper circuit D provided between a cylinder 2 and the tank 7 in the telescopic unit 1. The actuator circuit A has a thrust adjustment unit FT provided in a control passage 40 communicating a rod side chamber 5 with the tank 7. The damper circuit D includes a pressure side relief valve 27 on a pressure side damping passage 26 for connecting a piston side chamber 6 to the thrust adjustment unit FT.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a cylinder device. [Background technology]

[0002] Conventionally, cylinder devices exert thrust to drive an object on which the thrust acts, assist in the displacement of the object, or suppress vibration of the object. For example, in the case of a railroad car body, a cylinder device is installed horizontally between the car body and the bogie of the railroad car to suppress vibration in the lateral direction relative to the direction of travel of the car body. Some cylinder devices can function as actuators that actively apply thrust to the car body to suppress vibration of the car body, and as dampers that generate a damping force when expanding and contracting due to vibration of the car body to suppress vibration of the car body.

[0003] Such a cylinder device includes, for example, a cylinder, a rod movably inserted into the cylinder, a piston movably inserted into the cylinder and connected to the rod, and dividing the interior of the cylinder into a rod-side chamber and a piston-side chamber filled with hydraulic oil, a tank for storing the hydraulic oil, a first on-off valve provided in a first passage connecting the rod-side chamber and the piston-side chamber, a second on-off valve provided in a second passage connecting the piston-side chamber and the tank, a pump for supplying liquid to the rod-side chamber, a motor for driving the pump, a discharge passage connecting the rod-side chamber and the tank, a variable relief valve provided in the discharge passage capable of changing the valve opening pressure, a rectification passage that allows liquid to flow only from the piston-side chamber to the rod-side chamber, and a suction passage that allows liquid to flow only from the tank to the piston-side chamber (see, for example, Patent Document 1).

[0004] The cylinder device configured in this way enters damper mode when the pump is stopped and the first and second on-off valves are closed, and when it receives external force and performs extension / contraction operation, the hydraulic oil functions as a uniflow damper in which the hydraulic oil circulates through the tank, piston-side chamber, and rod-side chamber in that order before reaching the tank.The cylinder device then uses the variable relief valve to provide resistance to the flow of hydraulic oil discharged from the cylinder through the discharge passage to the tank during extension / contraction, generating a damping force that inhibits extension / contraction. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-060438 Summary of the Invention [Problem to be solved by the invention]

[0006] As mentioned above, conventional cylinder devices can function as both an actuator and a damper as needed, but in damper mode, they function as a uniflow damper. In a cylinder device in damper mode, hydraulic oil is discharged from the rod-side chamber, which contracts during extension, to the tank through the adjustable relief valve, and hydraulic oil is supplied from the tank via the suction passage to the piston-side chamber, which expands. Therefore, when a cylinder device in damper mode extends, the pressure in the rod-side chamber, which is increased by the adjustable relief valve, acts on the pressure-receiving surface of the piston facing the rod-side chamber, and tank pressure acts on the pressure-receiving surface of the piston facing the piston-side chamber. If the tank pressure is considered to be 0, a cylinder device in damper mode during extension generates a damping force equal to the pressure in the rod-side chamber multiplied by the pressure-receiving area on the rod-side chamber side of the piston.

[0007] On the other hand, when the cylinder device in the damper mode performs a contraction operation, hydraulic oil moves from the contracted piston side chamber to the rod side chamber through the rectifying passage, and hydraulic oil equivalent to the volume of the rod entering the cylinder is discharged from the cylinder to the tank through the variable relief valve. Therefore, when the cylinder device in the damper mode performs a contraction operation, the pressure-receiving portion of the piston on the rod side chamber side is Face and The pressure inside the cylinder, which has been increased by the variable relief valve, acts equally on both the pressure-receiving surface on the rod side chamber and the pressure-receiving surface on the piston side chamber. The difference between the pressure-receiving area on the rod side chamber of the piston and the pressure-receiving area on the piston side chamber is equal to the cross-sectional area of ​​the rod, so a cylinder device in damper mode during contraction generates a damping force equal to the pressure inside the cylinder multiplied by the cross-sectional area of ​​the rod.

[0008] Since the cylinder device suppresses lateral vibration of the car body relative to the bogie, if there is an imbalance between the damping force during extension and the damping force during retraction, the car body will undesirably shift toward the operating direction with the smaller damping force relative to the bogie as the extension and retraction movements are repeated. Therefore, a cylinder device that functions as a uniflow damper has a rod cross-sectional area set to half the cross-sectional area of ​​the piston, so that if the stroke amount within the cylinder is the same whether the cylinder is extended or retracted, the same flow rate of hydraulic oil passes through the variable relief valve, making it possible to generate the same damping force during extension and retraction. As such, conventional cylinder devices have design constraints on the rod diameter and piston diameter.

[0009] Here, hydraulic oil, which is the working medium of the cylinder device, has viscoelasticity, and in order to increase the damping coefficient of the cylinder device and generate a large damping force, it is necessary to increase the oil column rigidity. In order to increase the oil column rigidity, it is necessary to increase the pressure-receiving area of ​​the piston, so it is sufficient to increase the cylinder diameter, but doing so would also increase the rod diameter. Cylinder device with other equipment on the railcar but It is difficult to increase the cylinder diameter due to the risk of interference.

[0010] On the other hand, in a bi-flow damper, which generates an extension-side damping force by using an extension-side relief valve to resist the flow of hydraulic oil moving from the rod-side chamber to the piston-side chamber during extension, and generates a compression-side damping force by using a compression-side relief valve to resist the flow of hydraulic oil moving from the piston-side chamber to the tank during contraction, the extension-side damping force and the compression-side damping force can be set as desired using the extension-side relief valve and the compression-side relief valve, respectively, so the damping coefficient can be increased without increasing the cylinder diameter. However, with a bi-flow damper, when hydraulic oil is supplied to the piston-side chamber, the hydraulic oil escapes from the compression-side relief valve to the tank, making it difficult to use it as an actuator.

[0011] As described above, conventional cylinder devices have the drawback that increasing the damping coefficient results in an increase in the size of the cylinder device or causes problems in its use as an actuator. Note that this problem is not limited to cylinder devices used for railway vehicles, but is also the same when the object to which the cylinder device applies thrust is a vehicle, structure, machine, etc. other than railway vehicles, and increasing the damping coefficient results in an increase in the size of the cylinder device or causes problems in its use as an actuator.

[0012] Therefore, an object of the present invention is to provide a cylinder device that can function as an actuator without increasing its size, and can increase the damping coefficient when functioning as a damper. [Means for solving the problem]

[0013] The cylinder device of the present invention includes a telescopic unit having a cylinder, a rod movably inserted into the cylinder, and a piston movably inserted into the cylinder and connected to the rod to divide the inside of the cylinder into a rod-side chamber and a piston-side chamber; a tank; a pump capable of supplying liquid from the tank to the cylinder; an adjustment passage communicating between the rod-side chamber and the tank and having a variable relief valve provided therein; a bypass passage communicating between the rod-side chamber and the tank and having a relief valve and a bypass passage opening / closing valve provided in series therein, and capable of driving the telescopic unit to extend and retract; an extension-side damping passage communicating between the rod-side chamber and the piston-side chamber; an extension-side relief valve provided in the extension-side damping passage to provide resistance to the flow of liquid from the rod-side chamber to the piston-side chamber; a damper circuit including: a compression side damping passage connected between the bypass passage on-off valve; a compression side relief valve provided in the compression side damping passage to provide resistance to the flow of liquid from the piston side chamber to the tank; a suction passage connecting the tank and the piston side chamber; and a suction check valve provided in the suction passage to allow the flow of liquid from the tank to the piston side chamber; the variable relief valve and the bypass passage on-off valve are electromagnetic valves driven by the same solenoid, and the variable relief valve is capable of adjusting its valve opening pressure when the solenoid is energized, and the bypass passage on-off valve closes when the solenoid is energized and opens when the solenoid is not energized, and closes the bypass passage on-off valve to shut off the bypass passage in an actuator mode in which the pump is driven, and opens the bypass passage on-off valve to open the bypass passage in a damper mode in which the pump is stopped.

[0014] The cylinder device of this embodiment configured in this manner can function as both an actuator and a damper, and when functioning as a damper, the damping force characteristics during extension operation and the damping force characteristics during contraction operation can be set to the same characteristics by setting the extension side relief valve and the compression side relief valve, regardless of the settings of the rod diameter and the cylinder diameter.

[0015] Furthermore, the cylinder device configured in this manner can function as an actuator by supplying fluid from the pump to the cylinder via the actuator circuit and blocking the compression side damping passage with the bypass path on-off valve, and can also function as a damper by stopping the pump and opening the compression side damping passage with the bypass path on-off valve and using the damper circuit.Furthermore, when functioning as a damper, the cylinder device configured in this manner can generate damping force via the extension side relief valve when the telescopic unit is extended, and generate damping force via the compression side relief valve when the telescopic unit is retracted.

[0016] Another cylinder device of the present invention includes a telescopic unit having a cylinder, a rod movably inserted into the cylinder, and a piston movably inserted into the cylinder and connected to the rod to divide the inside of the cylinder into a rod-side chamber and a piston-side chamber; a tank, a pump capable of supplying liquid from the tank to the cylinder, a control passage connecting the rod-side chamber and the tank, and a thrust adjuster provided in the control passage, and capable of driving the telescopic unit to extend and retract; an extension-side damping passage connecting the rod-side chamber and the piston-side chamber; an extension-side relief valve provided in the extension-side damping passage and providing resistance to the flow of liquid from the rod-side chamber to the piston-side chamber; and a compression-side damping valve connecting the piston-side chamber to the thrust adjuster. the thrust adjustment unit includes a damper circuit including a damping passage, a compression side relief valve provided in the compression side damping passage and providing resistance to the flow of liquid from the piston side chamber to the tank, a suction passage connecting the tank and the piston side chamber, and a suction check valve provided in the suction passage and allowing the flow of liquid from the tank to the piston side chamber, and the thrust adjustment unit has an adjustment passage provided in the middle of the control passage, a relief valve that opens when the pressure on the rod side chamber side reaches a valve opening pressure, and a variable relief valve whose valve opening pressure can be adjusted by energizing, and the relief valve and the variable relief valve are arranged in series in the adjustment passage from the rod side chamber side, and the compression side damping passage is connected to the piston side chamber between the relief valve in the adjustment passage and the variable relief valve.

[0017] Another cylinder device of the present invention configured in this manner can function as both an actuator and a damper, and when functioning as a damper, the damping force characteristics during extension operation and the damping force characteristics during contraction operation can be set to the same characteristics by setting the extension side relief valve and the compression side relief valve, regardless of the settings of the rod diameter and the cylinder diameter.

[0018] In a cylinder device configured in this manner, even if the thrust adjustment unit does not have an on-off valve that blocks the compression side damping passage in the actuator mode, the compression side damping force can be generated using the compression side relief valve in the damper mode.This simplifies the configuration of the thrust adjustment unit and does not require an on-off valve, thereby reducing manufacturing costs.

[0019] Furthermore, the cylinder device may have an actuator circuit that has an adjustable valve opening pressure that adjusts the pressure of the fluid supplied from the pump into the cylinder by adjusting the valve opening pressure, and the valve opening pressure of the extension-side relief valve may be set to be higher than the maximum valve opening pressure that the adjustable relief valve can attain in actuator mode. With the cylinder device configured in this way, when it functions as an actuator, the fluid supplied from the pump into the cylinder is not allowed to escape from the rod-side chamber to the piston-side chamber, so that it can generate a contraction-side thrust efficiently and also reduce energy consumption. [Effects of the Invention]

[0020] According to the cylinder device of the present invention, it is possible to improve the damping coefficient when functioning as a damper while still functioning as an actuator without increasing the size. [Brief explanation of the drawings]

[0021] [Figure 1] 2 is a circuit diagram of the cylinder device according to the first embodiment. FIG. [Figure 2] FIG. 1 is a diagram showing a state in which a cylinder device is interposed between a car body and a bogie of a railway vehicle. [Figure 3] FIG. 6 is a circuit diagram of a cylinder device according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0022] The present invention will be described below based on the embodiments shown in the drawings. In the cylinder devices of the embodiments, members and components assigned common reference numerals have the same configuration. Therefore, to avoid repetition, a detailed description of a configuration that has been explained in detail in the explanation of a cylinder device of one embodiment will not be repeated in the explanation of cylinder devices of other embodiments. Note that, in explaining the cylinder device of the present invention, each embodiment uses a cylinder device applied to a railway vehicle as an example, but the cylinder device of the present invention can also be used to suppress the drive and vibration of vehicles other than railway vehicles, structures, buildings, and even machines.

[0023] First Embodiment The present invention will be described below based on the embodiments shown in the drawings. As shown in Fig. 1, the cylinder device C in the first embodiment is configured to include an extension unit 1, a tank 7, an actuator circuit A, and a damper circuit D. In this embodiment, two cylinder devices C are installed in parallel between the car body S and the bogie B of the railway vehicle T as shown in Fig. 2, to suppress horizontal vibration of the car body S, but it is also possible to use a single cylinder device C installed between the car body S and the bogie B.

[0024] Below, we will explain each part of the cylinder device C. The telescopic unit 1 includes a cylinder 2, a rod 3 that is movably inserted into the cylinder 2, and a piston 4 that is movably inserted into the cylinder 2 and connected to the rod 3 to divide the inside of the cylinder 2 into a rod-side chamber 5 and a piston-side chamber 6.

[0025] The rod side chamber 5 and the piston side chamber 6 are filled with hydraulic oil as a liquid, and the tank 7 is filled with gas in addition to hydraulic oil. In addition to hydraulic oil, water or an aqueous solution can also be used as the liquid. The inside of the tank 7 does not need to be pressurized by compressing and filling the gas, but it may be pressurized.

[0026] 1 is closed by a lid 19, and an annular rod guide 20 is attached to the left end in FIG. 1. A rod 3 is movably inserted into the cylinder 2 on the inner periphery of the rod guide 20. One end of the rod 3 is connected to a piston 4 that is movably inserted into the cylinder 2, and the other end protrudes outside the cylinder 2, so that the rod 3 is axially movable relative to the cylinder 2.

[0027] The cylinder device C also includes an outer cylinder 21 that covers the outer periphery of the cylinder 2. The left and right ends of the outer cylinder 21 in FIG. 1 are closed by a lid 19 and a rod guide 20, similar to the cylinder 2, and a tank 7 is formed in the annular gap between the outer cylinder 21 and the cylinder 2. The lid 19 that closes the left end of the rod 3 in FIG. 1 and the right end of the cylinder 2 is provided with a mounting portion (not shown), and the cylinder device C can be interposed between the car body S and the bogie B of the railway vehicle T.

[0028] The actuator circuit A is provided between the cylinder 2 and the tank 7, and includes a pump 14 capable of supplying hydraulic oil from the tank 7 to the cylinder 2, and is a circuit that drives the extension and retraction of the telescopic unit 1. By driving the pump 14, the actuator circuit A supplies hydraulic oil into the cylinder 2 to select either the extension direction or the retraction direction of the telescopic unit 1, causing the telescopic unit 1 to generate thrust in the selected direction, and can also adjust the thrust.

[0029] Specifically, as shown in FIG. 1 , the actuator circuit A is provided between the cylinder 2 and the tank 7, and includes a pump 14 that supplies hydraulic oil to the rod-side chamber 5, a motor 15 that drives the pump 14, a control passage 40 that connects the rod-side chamber 5 and the tank 7, a thrust adjustment unit FT provided in the control passage 40, a first passage 10 that connects the rod-side chamber 5 and the piston-side chamber 6, a first on-off valve 11 provided in the first passage 10, a second passage 12 that connects the piston-side chamber 6 and the tank 7, and a second on-off valve 13 provided in the second passage 12.

[0030] The pump 14 is driven by the motor 15, and in the cylinder device C of this embodiment, the pump 14 discharges hydraulic oil in only one direction. The discharge port of the pump 14 is connected to the rod side chamber 5 through a supply passage 22 that connects the rod side chamber 5 and the tank 7, and the suction port is connected to the tank 7 through the supply passage 22. Therefore, when the pump 14 is driven by the motor 15, it draws hydraulic oil from the tank 7 and supplies the hydraulic oil to the rod side chamber 5.

[0031] As described above, the pump 14 discharges hydraulic oil in only one direction and does not switch its rotation direction, so there is no problem with the discharge amount changing when the rotation direction is switched, and an inexpensive gear pump or the like can be used. Furthermore, because the rotation direction of the pump 14 is always the same, the motor 15, which is the drive source that drives the pump 14, does not require high responsiveness to rotation switching, so an inexpensive motor 15 can be used. The supply passage 22 is provided with a check valve 23 that prevents backflow of hydraulic oil from the rod-side chamber 5 to the pump 14.

[0032] In addition, in the actuator circuit A of this embodiment, a first on-off valve 11 is provided in a first passage 10 that communicates between the rod side chamber 5 and the piston side chamber 6, and a second on-off valve 13 is provided in a second passage 12 that communicates between the piston side chamber 6 and the tank 7.

[0033] In this embodiment, the first on-off valve 11 is an electromagnetic on-off valve, and is configured to include a valve element 11a having a communication position 11b that opens the first passage 10 to communicate between the rod side chamber 5 and the piston side chamber 6 and a blocking position 11c that blocks communication between the rod side chamber 5 and the piston side chamber 6, a spring 11d that urges the valve element 11a to take the blocking position 11c, and a solenoid 11e that switches the valve element 11a to the communication position 11b against the spring 11d when energized.

[0034] In this embodiment, the second on-off valve 13 is an electromagnetic on-off valve, and is configured to include a valve element 13a having a communication position 13b that opens the second passage 12 to communicate between the piston side chamber 6 and the tank 7 and a blocking position 13c that blocks communication between the piston side chamber 6 and the tank 7, a spring 13d that urges the valve element 13a to take the blocking position 13c, and a solenoid 13e that switches the valve element 13a to the communication position 13b against the spring 13d when energized.

[0035] The thrust adjustment section FT includes an adjustment passage P1 and a bypass passage P2 connected in parallel midway through a control passage 40 that communicates between the rod side chamber 5 and the tank 7, a variable relief valve 41 provided in the adjustment passage P1, and a relief valve 43 and a bypass passage opening / closing valve 44 provided in series in the bypass passage P2 in this order from the rod side chamber 5 side.

[0036] As described above, in the cylinder device C of the first embodiment, the rod-side chamber 5 and the tank 7 are connected to each other through the control passage 40, the adjustment passage P1, and the bypass passage P2 provided in the middle of the control passage 40. As described above, the adjustment passage P1 is provided with the variable relief valve 41 capable of changing the valve opening pressure, and the bypass passage P2 is provided with the relief valve 43 and the bypass passage opening / closing valve 44 in series.

[0037] The relief valve 43 includes a valve element 43a provided in the bypass passage P2, a spring 43b that biases the valve element 43a so as to block the bypass passage P2, and a pilot passage 43c that causes the pressure on the rod-side chamber upstream of the valve element 43a to act on the valve element 43a in the valve-opening direction against the force of the spring 43b. The valve-opening pressure of the relief valve 43 is set in advance to a predetermined valve-opening pressure by the force of the spring 43b that biases the valve element 43a.

[0038] When the bypass passage opening / closing valve 44 provided downstream of the relief valve 43 is in an open state, if the pressure in the rod side chamber 5 upstream of the bypass passage P2 acting on the valve body 43a exceeds the relief pressure (valve opening pressure) of the relief valve 43, the force of this pressure pressing on the valve body 43a overcomes the force of the spring 43b biasing the valve body 43a, causing the valve body 43a to move backward and the relief valve 43 to open the bypass passage P2.

[0039] The bypass passage on-off valve 44 is configured to include an openable and closable valve element 44a provided on the tank side of the bypass passage P2 downstream of the relief valve 43, a spring 44b that biases the valve element 44a to open the bypass passage P2, and a solenoid Sol that, when energized, generates a thrust that counteracts the spring 44b and switches the valve element 44a to a position that blocks the bypass passage P2. In this way, the bypass passage on-off valve 44 is a solenoid valve that blocks the bypass passage P2 when a current of a predetermined value or more is applied to the solenoid Sol, causing the solenoid Sol to generate a thrust that exceeds the biasing force of the spring 44b.

[0040] Furthermore, when the solenoid Sol is not energized, that is, when no current is supplied to the solenoid Sol, the valve element 44a of the bypass passage opening / closing valve 44 is biased by the spring 44b to assume a position that opens the bypass passage P2. In other words, when the solenoid Sol is not energized, the bypass passage opening / closing valve 44 opens to open the bypass passage P2.

[0041] The adjustable relief valve 41 includes a valve element 41a provided in the adjustment passage P1, a spring 41b that biases the valve element 41a to close the adjustment passage P1, a pilot passage 41c that causes pressure in the rod-side chamber upstream of the valve element 41a to act on the valve element 41a in the valve-opening direction against the spring 41b, and a solenoid Sol that generates a thrust force that counteracts the spring 41b when energized. The adjustable relief valve 41 is an electromagnetic valve that can adjust the valve-opening pressure by adjusting the amount of current flowing through the solenoid Sol. The thrust force of the solenoid Sol is transmitted to the valve element 41a of the adjustable relief valve 41 via a valve element 44a. More specifically, when a current of a predetermined value or more is supplied to the solenoid Sol, the valve element 44a of the bypass passage opening / closing valve 44 blocks the bypass passage P2 and contacts the valve element 41a of the variable relief valve 41 to transmit the thrust of the solenoid Sol to the valve element 41a.

[0042] Then, when the pressure in the rod side chamber 5 upstream of the control passage 40 acting on the valve body 41a exceeds the relief pressure (valve opening pressure) of the variable relief valve 41, the force of this pressure and the solenoid Sol pushing the valve body 41a overcomes the combined force of the biasing force of the spring 41b biasing the valve body 41a and the biasing force of the spring 44b biasing the valve body 44a, causing the valve body 41a to move back and the variable relief valve 41 to open the adjustment passage P1.

[0043] Furthermore, in the adjustable relief valve 41, increasing the amount of current supplied to the solenoid Sol can increase the thrust generated by the solenoid Sol. Therefore, when the amount of current supplied to the solenoid Sol is maximized, the valve opening pressure of the adjustable relief valve 41 is minimized. Conversely, when no current is supplied to the solenoid Sol, the valve opening pressure of the adjustable relief valve 41 is maximized. Furthermore, when the amount of current supplied to the solenoid Sol is changed while being equal to or greater than a predetermined value, the valve opening pressure of the adjustable relief valve 41 can be changed while the bypass passage opening / closing valve 44 is closed. In this way, the adjustable relief valve 41 and the bypass passage opening / closing valve 44 share a single solenoid Sol and are electromagnetic valves driven by the same solenoid Sol. Therefore, the thrust of the solenoid Sol can be applied to the valve bodies 41a, 44a of the adjustable relief valve 41 and the bypass passage opening / closing valve 44, respectively.

[0044] When the solenoid Sol is energized, not only can the valve opening pressure of the adjustable relief valve 41 be adjusted according to the amount of current supplied to the solenoid Sol, but also the bypass passage opening / closing valve 44 can be closed. Conversely, when the solenoid Sol is not energized, that is, when no current is supplied to the solenoid Sol, the valve opening pressure of the adjustable relief valve 41 can be maximized, while the bypass passage opening / closing valve 44 can be opened.

[0045] Regardless of the open / closed states of the first on-off valve 11 and the second on-off valve 13, when an excessive input in the extension / retraction direction is applied to the telescopic unit 1 and the pressure in the rod side chamber 5 exceeds the valve opening pressure, the adjustable relief valve 41 opens the adjustment passage P1 to connect the rod side chamber 5 to the tank 7. In this way, in response to an excessive input to the telescopic unit 1, the adjustable relief valve 41 discharges the pressure in the rod side chamber 5 to the tank 7, protecting the entire system of the cylinder device C.

[0046] Next, the damper circuit D includes an extension-side damping passage 24 communicating between the rod-side chamber 5 and the piston-side chamber 6, an extension-side relief valve 25 provided in the extension-side damping passage 24 and providing resistance to the flow of hydraulic oil from the rod-side chamber 5 toward the piston-side chamber 6, a compression-side damping passage 26 connecting the piston-side chamber 6 to the thrust adjusting unit FT, a first compression-side relief valve 27 provided in the compression-side damping passage 26 and providing resistance to the flow of hydraulic oil from the piston-side chamber 6 toward the tank 7, and a suction passage 28 communicating between the tank 7 and the piston-side chamber 6. a suction check valve 29 provided in the suction passage 28 to allow the flow of hydraulic oil from the tank 7 to the piston-side chamber 6; an extension-side suction passage 30 communicating between the tank 7 and the rod-side chamber 5; an extension-side check valve 31 provided in the extension-side suction passage 30 to allow only the flow of hydraulic oil from the tank 7 to the rod-side chamber 5; a compression-side passage 32 communicating between the piston-side chamber 6 and the rod-side chamber 5; and a second compression-side relief valve 33 provided in the compression-side passage 32 to provide resistance to the flow of hydraulic oil from the piston-side chamber 6 to the rod-side chamber 5.

[0047] The extension-side damping passage 24 is provided in the piston 4 and communicates between the rod-side chamber 5 and the piston-side chamber 6. The extension-side relief valve 25 is provided in the piston 4 and opens when the pressure in the rod-side chamber 5 exceeds the pressure in the piston-side chamber 6 and the difference between the pressure in the rod-side chamber 5 and the pressure in the piston-side chamber 6 reaches a valve-opening pressure, thereby providing resistance to the flow of hydraulic oil from the rod-side chamber 5 to the piston-side chamber 6. The extension-side relief valve 25 closes the extension-side damping passage 24 against the flow of hydraulic oil from the piston-side chamber 6 to the rod-side chamber 5, thereby blocking the extension-side damping passage 24. Therefore, the extension-side relief valve 25 sets the extension-side damping passage 24 as a one-way passage that only allows the flow of hydraulic oil from the rod-side chamber 5 to the piston-side chamber 6.

[0048] The opening pressure of the extension side relief valve 25 is set to be equal to or greater than the difference between the pressure in the rod side chamber 5 and the pressure in the piston side chamber 6 when the telescopic unit 1 generates the maximum thrust in the retraction direction by the actuator circuit A. Therefore, even if the pump 14 in the actuator circuit A is driven to generate the maximum thrust in the retraction direction in the telescopic unit 1, the extension side relief valve 25 does not open, and keeps the extension side damping passage 24 blocked.

[0049] The compression side damping passage 26 connects the piston side chamber 6 to the thrust adjustment unit FT. Specifically, the compression side damping passage 26 connects the piston side chamber 6 to a position between the relief valve 43 and the bypass passage on-off valve 44 of the bypass passage P2. Therefore, when the bypass passage on-off valve 44 is in an open state, the piston side chamber 6 is connected to the tank 7 via the compression side damping passage 26, the bypass passage on-off valve 44, the bypass passage P2, and the control passage 40 downstream of the thrust adjustment unit FT. Note that when the bypass passage on-off valve 44 is in a closed state, communication between the piston side chamber 6 and the tank 7 via the compression side damping passage 26 is cut off. Because the compression side damping passage 26 is connected between the relief valve 43 and the bypass passage on-off valve 44 of the bypass passage P2, the compression side damping passage 26 can be switched between being blocked and being connected by opening or closing the bypass passage on-off valve 44, which is arranged downstream of the compression side damping passage 26.

[0050] Furthermore, when the bypass passage opening / closing valve 44 is open, the first compression-side relief valve 27, which serves as a compression-side relief valve, opens when the pressure in the piston-side chamber 6 exceeds the pressure in the tank 7 and the difference between the pressure in the piston-side chamber 6 and the pressure in the tank 7 reaches a valve-opening pressure, thereby providing resistance to the flow of hydraulic oil from the piston-side chamber 6 to the tank 7. The first compression-side relief valve 27 closes the compression-side damping passage 26 to block the flow of hydraulic oil from the tank 7 to the piston-side chamber 6. Therefore, the first compression-side relief valve 27 sets the compression-side damping passage 26 as a one-way passage that allows only the flow of hydraulic oil from the piston-side chamber 6 to the tank 7. When the bypass passage opening / closing valve 44 is closed, communication between the piston-side chamber 6 and the tank 7 via the compression-side damping passage 26 is cut off, and therefore the first compression-side relief valve 27 does not open.

[0051] Next, the suction passage 28 communicates between the tank 7 and the piston-side chamber 6. Furthermore, the suction check valve 29 opens when the pressure in the tank 7 exceeds the pressure in the piston-side chamber 6, allowing the passage of hydraulic oil from the tank 7 to the piston-side chamber 6 without much resistance. The suction check valve 29 closes the suction passage 28 to block the flow of hydraulic oil from the piston-side chamber 6 to the tank 7. Therefore, the suction passage 28 is set by the suction check valve 29 as a one-way passage that allows the flow of hydraulic oil only from the tank 7 to the piston-side chamber 6.

[0052] Furthermore, the extension-side suction passage 30 communicates between the tank 7 and the rod-side chamber 5. Furthermore, the extension-side check valve 31 opens when the pressure in the tank 7 exceeds the pressure in the rod-side chamber 5, allowing the passage of hydraulic oil from the tank 7 to the rod-side chamber 5 without much resistance. Note that the extension-side check valve 31 closes the extension-side suction passage 30 against the flow of hydraulic oil from the rod-side chamber 5 to the tank 7, thereby blocking the extension-side suction passage 30. Therefore, the extension-side check valve 31 sets the extension-side suction passage 30 as a one-way passage that allows only the flow of hydraulic oil from the tank 7 to the rod-side chamber 5.

[0053] The compression-side passage 32 is provided in the piston 4, and connects the piston-side chamber 6 and the rod-side chamber 5. The second compression-side relief valve 33 is provided in the piston 4, and opens when the pressure in the piston-side chamber 6 exceeds the pressure in the rod-side chamber 5 and the difference between the pressures in the piston-side chamber 6 and the rod-side chamber 5 reaches a valve-opening pressure, thereby providing resistance to the flow of hydraulic oil from the piston-side chamber 6 to the rod-side chamber 5. The second compression-side relief valve 33 closes the compression-side passage 32 to block the flow of hydraulic oil from the rod-side chamber 5 to the piston-side chamber 6. Therefore, the second compression-side relief valve 33 sets the compression-side passage 32 as a one-way passage that only allows the flow of hydraulic oil from the piston-side chamber 6 to the rod-side chamber 5.

[0054] The cylinder device C is configured as described above, and the operation of the cylinder device C will be described below. First, the actuator mode in which the cylinder device C functions as an actuator using the actuator circuit A will be described. When generating thrust in the extension direction in the cylinder device C, the first on-off valve 11 is set to the communicating position 11b, the second on-off valve 13 is set to the blocking position 13c, and the pump 14 is driven by the motor 15 to supply hydraulic oil from the tank 7 to the cylinder 2. Also, a current of a predetermined value or more is applied to the solenoid Sol to close the bypass passage on-off valve 44 and block the bypass passage P2, and the valve opening pressure of the variable relief valve 41 is adjusted according to the thrust to be generated by the cylinder device C.

[0055] In this manner, the rod side chamber 5 and the piston side chamber 6 are placed in a state of communication through the first passage 10 by opening the first on-off valve 11, and hydraulic oil is supplied from the pump 14 to the rod side chamber 5 and the piston side chamber 6. Furthermore, the bypass passage on-off valve 44 is closed, and therefore the compression side damping passage 26 is blocked, and therefore the hydraulic oil supplied into the cylinder 2 cannot move from the piston side chamber 6 to the tank 7. In this way, during the actuator mode in which the cylinder device C functions as an actuator, the compression side damping passage 26 is blocked by the bypass passage on-off valve 44.

[0056] Therefore, when the first on-off valve 11 is set to the communication position 11b and the second on-off valve 13 is set to the shut-off position 13c and the pump 14 is driven by the motor 15, the hydraulic oil supplied from the pump 14 into the cylinder 2 presses the piston 4 against the cylinder 2 in a direction that pushes it out to the left in Figure 1, and the cylinder device C generates a thrust in the extension direction.

[0057] When the pressure in the rod-side chamber 5 and the piston-side chamber 6 exceeds the valve opening pressure of the adjustable relief valve 41, the adjustable relief valve 41 opens and the hydraulic oil is discharged to the tank 7 via the adjustment passage P1, and the pressure in the rod-side chamber 5 and the piston-side chamber 6 becomes equal to the valve opening pressure of the adjustable relief valve 41. In this way, the adjustable relief valve 41 adjusts the pressure of the hydraulic oil supplied from the pump 14 to the cylinder 2 by adjusting the valve opening pressure. Therefore, the cylinder device C generates a thrust in the extension direction calculated by multiplying the pressure-receiving area difference between the piston-side chamber side and the rod-side chamber side of the piston 4 by the valve opening pressure of the adjustable relief valve 41, and the thrust can be adjusted by adjusting the valve opening pressure of the adjustable relief valve 41. In this state, even if the telescopic unit 1 is forcibly retracted by an external force, the pressure in the rod-side chamber 5 and the piston-side chamber 6 is controlled to be equal to the valve opening pressure of the adjustable relief valve 41, so a thrust in the extension direction that suppresses the retraction is generated.

[0058] If the telescopic unit 1 contracts at high speed due to an external force while the cylinder device C is generating thrust in the extension direction, causing the pressure inside the piston side chamber 6 to become abnormally high, the second compression-side relief valve 33 opens to move the hydraulic oil inside the piston side chamber 6 to the rod-side chamber 5, thereby protecting the cylinder device C.

[0059] On the other hand, when a thrust in the contraction direction is to be generated in the cylinder device C, the first on-off valve 11 is set to the shutoff position 11c, the second on-off valve 13 is set to the communication position 13b, the pump 14 is driven by the motor 15, and hydraulic oil is supplied from the tank 7 to the rod-side chamber 5. Also, a current of a predetermined value or more is applied to the solenoid Sol to close the bypass passage on-off valve 44 and shut off the bypass passage P2, and the valve opening pressure of the variable relief valve 41 is adjusted according to the thrust to be exerted by the cylinder device C.

[0060] By doing so, the piston-side chamber 6 and the tank 7 are brought into a state of communication through the second passage 12 by opening the second on-off valve 13, and the first on-off valve 11 is closed to cut off communication between the rod-side chamber 5 and the piston-side chamber 6, so that the hydraulic oil discharged from the pump 14 is supplied only to the rod-side chamber 5. In addition, the bypass passage on-off valve 44 is closed to cut off the compression-side damping passage 26, but the piston-side chamber 6 and the tank 7 are communicated with each other through the second passage 12.

[0061] Therefore, when the pump 14 is driven by the motor 15 with the first on-off valve 11 at the shutoff position 11c and the second on-off valve 13 at the communicating position 13b, hydraulic oil supplied from the pump 14 to the rod side chamber 5 presses the piston 4 toward the right in FIG. 1 relative to the cylinder 2, causing the cylinder device C to generate a thrust in the contraction direction. The cylinder device C generates a thrust in the contraction direction equal to the value obtained by multiplying the pressure-receiving area of ​​the piston 4 on the rod side chamber side by the valve opening pressure of the adjustable relief valve 41 minus the value obtained by multiplying the pressure-receiving area of ​​the piston 4 on the piston side chamber side by the pressure of the tank 7, and the thrust can be adjusted by adjusting the valve opening pressure of the adjustable relief valve 41. In this state, even if the telescopic unit 1 is forcibly extended by an external force, the pressure in the rod side chamber 5 is controlled to be equal to the valve opening pressure of the adjustable relief valve 41, so a thrust in the contraction direction that suppresses extension is generated.

[0062]

[0043] When generating a thrust in the contraction direction in the cylinder device C of this embodiment, as described above, it is necessary to supply hydraulic oil to the rod-side chamber 5 with the communication between the rod-side chamber 5 and the piston-side chamber 6 cut off. Here, the extension-side damping passage 24 in the damper circuit D allows hydraulic oil to flow from the rod-side chamber 5 to the piston-side chamber 6 when the extension-side relief valve 25 opens. Therefore, when generating a thrust in the contraction direction in the cylinder device C of this embodiment, if the extension-side relief valve 25 opens, hydraulic oil escapes from the rod-side chamber 5 to the piston-side chamber 6, reducing efficiency. However, the valve opening pressure of the extension-side relief valve 25 is set to be equal to or greater than the difference between the pressure in the rod-side chamber 5 and the pressure in the piston-side chamber 6 when the actuator circuit A causes the telescopic unit 1 to generate a maximum thrust in the contraction direction. The maximum thrust in the contraction direction of the cylinder device C in the actuator mode is generated when the valve opening pressure of the adjustable relief valve 41 is maximized. Therefore, when the cylinder device C of this embodiment functions as an actuator that generates thrust in the contraction direction, the extension-side relief valve 25 does not open even when the valve opening pressure of the adjustable relief valve 41 is set to its maximum, and prevents hydraulic oil from moving from the rod-side chamber 5 to the piston-side chamber 6 through the extension-side damping passage 24. In this way, if the valve opening pressure of the extension-side relief valve 25 is set to be equal to or greater than the difference between the pressure in the rod-side chamber 5 and the pressure in the piston-side chamber 6 when the telescopic unit 1 generates the maximum thrust in the contraction side by the actuator circuit A, the cylinder device C can generate thrust efficiently when generating thrust in the contraction direction as an actuator, and energy consumption is also reduced. As described above, in the cylinder device C of this embodiment, it is sufficient that the extension-side relief valve 25 does not open even when the variable relief valve 41 that controls the pressure in the rod-side chamber 5 reaches its maximum valve opening pressure, and therefore the valve opening pressure of the extension-side relief valve 25 only needs to be higher than the maximum valve opening pressure of the adjustable relief valve 41. In this case, the valve opening pressure of the extension side relief valve 25 may be higher than the maximum valve opening pressure that the adjustable relief valve 41 can control in the actuator mode, rather than the maximum valve opening pressure that the adjustable relief valve 41 can control in the actuator mode.

[0063] As mentioned above, from the viewpoint of efficiency, it is advisable to set the valve opening pressure of the extension-side relief valve 25 to be equal to or greater than the difference between the pressure in the rod-side chamber 5 and the pressure in the piston-side chamber 6 when the telescopic unit 1 generates the maximum thrust to the contraction side by the actuator circuit A. However, even if the valve opening pressure is set to be less than the difference, the cylinder device C can generate thrust in the contraction direction as an actuator.

[0064] If the telescopic unit 1 is extended at high speed by an external force while the cylinder device C is generating thrust in the contraction direction, causing the pressure inside the rod-side chamber 5 to become abnormally high, the extension-side relief valve 25 opens to move the hydraulic oil inside the rod-side chamber 5 to the piston-side chamber 6, thereby protecting the cylinder device C.

[0065] In this way, the cylinder device C can generate thrust in both the extension direction and the contraction direction within the adjustment range of the valve opening pressure of the variable relief valve 41 by opening and closing the first on-off valve 11 and the second on-off valve 13 and adjusting the valve opening pressure of the variable relief valve 41. Therefore, in the actuator mode, the cylinder device C can suppress vibration of the vehicle body S by controlling the first on-off valve 11, the second on-off valve 13, and the variable relief valve 41 while driving the pump 14.

[0066] Next, a damper mode will be described in which the cylinder device C functions as a damper using the damper circuit D. When the cylinder device C is set to the damper mode, the first on-off valve 11 is set to the shut-off position 11c, the second on-off valve 13 is set to the shut-off position 13c, the motor 15 is not driven, and the pump 14 is stopped. In addition, the solenoid Sol is de-energized, and the bypass passage on-off valve 44 is opened to open the bypass passage P2.

[0067] In this state, communication between the rod-side chamber 5 and the piston-side chamber 6 through the first passage 10 is cut off, and communication between the piston-side chamber 6 and the tank 7 through the second passage 12 is cut off. Then, the bypass passage opening / closing valve 44 is opened by stopping the supply of current to the solenoid Sol, so that the piston-side chamber 6 and the tank 7 are communicated with each other through the compression-side damping passage 26. In this way, in the damper mode in which the cylinder device C functions as a damper, the compression-side damping passage 26 is opened by opening the bypass passage opening / closing valve 44.

[0068] When the telescopic unit 1 is extended by an external force with the cylinder device C in the damper mode, the piston 4 moves leftward in FIG. 1 relative to the cylinder 2, contracting the rod-side chamber 5 and expanding the piston-side chamber 6. The hydraulic oil in the contracting rod-side chamber 5 passes through either the relief valve 43 in the bypass passage P2 or the extension-side relief valve 25 in the extension-side damping passage 24, or both, and moves to the tank 7 or the expanding piston-side chamber 6 while being resisted by either the relief valve 43 or the extension-side relief valve 25. When the telescopic unit 1 is extended, the rod 3 retracts from the cylinder 2, causing a shortage of hydraulic oil in the cylinder 2. However, the suction check valve 29 opens, and the shortage of hydraulic oil is supplied from the tank 7 to the piston-side chamber 6 through the suction passage 28. In this way, when the cylinder device C is in the damper mode and the telescopic unit 1 is extended, the pressure in the rod-side chamber 5 increases due to the relief valve 43 and the extension-side relief valve 25, and the pressure in the piston-side chamber 6 becomes equal to the tank pressure. Therefore, the cylinder device C generates a damping force in a direction that hinders the extension of the telescopic unit 1, the damping force being equal to the value obtained by multiplying the pressure-receiving area on the rod-side chamber side of the piston 4 by the pressure in the rod-side chamber 5 minus the value obtained by multiplying the pressure-receiving area on the piston-side chamber side of the piston 4 by the pressure in the tank 7.

[0069] Furthermore, when the telescopic unit 1 is contracted by an external force with the cylinder device C in the damper mode, the piston 4 moves rightward in FIG. 1 relative to the cylinder 2, contracting the piston-side chamber 6 and expanding the rod-side chamber 5. The hydraulic oil in the contracting piston-side chamber 6 passes through the second compression-side relief valve 33 of the compression-side passage 32 and moves to the expanding rod-side chamber 5. When the telescopic unit 1 is contracted, the rod 3 enters the cylinder 2, causing an excess of hydraulic oil in the cylinder 2. However, the first compression-side relief valve 27 opens and the excess hydraulic oil is discharged from the piston-side chamber 6 to the tank 7 through the compression-side damping passage 26. In this way, when the cylinder device C is in the damper mode and the telescopic unit 1 is contracted, the pressure in the piston-side chamber 6 increases due to the first compression-side relief valve 27 and the second compression-side relief valve 33, the pressure in the rod-side chamber 5 is reduced, and the pressure in the piston-side chamber 6 becomes higher than the pressure in the rod-side chamber 5. Therefore, the cylinder device C generates a damping force in a direction that hinders contraction of the telescopic unit 1, equal to the value obtained by multiplying the pressure-receiving area on the piston-side chamber side of the piston 4 by the pressure in the piston-side chamber 6 minus the value obtained by multiplying the pressure-receiving area on the rod-side chamber side of the piston 4 by the pressure in the rod-side chamber 5. In the cylinder device C of this embodiment, since the damper circuit D is equipped with the extension-side suction passage 30 and the extension-side check valve 31, when the telescopic unit 1 contracts in the cylinder device C in the damper mode, if the pressure in the rod-side chamber 5 falls below the tank pressure, the extension-side check valve 31 opens and hydraulic oil is supplied from the tank 7 to the rod-side chamber 5. Therefore, when the cylinder device C of this embodiment contracts in the damper mode, the pressure in the rod-side chamber 5 does not become negative, and aeration or a delay in the generation of the damping force when the telescopic unit 1 switches from contraction to extension is avoided.

[0070] In this way, in the damper mode, when the telescopic unit 1 is extended or retracted by an external force, the cylinder device C generates a damping force that hinders the extension or retraction of the telescopic unit 1. Then, when the telescopic unit 1 is extended, the cylinder device C in the damper mode generates a damping force by one or both of the relief valve 43 and the extension-side relief valve 25, and when the telescopic unit 1 is retracted, the cylinder device C generates a damping force by the first compression-side relief valve 27 and the second compression-side relief valve 33. Therefore, the damping force characteristics of the damping force generated in response to the piston speed during extension operation of the cylinder device C in the damper mode are set by the relief valve 43 and the extension-side relief valve 25, and the damping force characteristics of the damping force generated in response to the piston speed during retraction operation of the cylinder device C in the damper mode are set by the first compression-side relief valve 27 and the second compression-side relief valve 33, so that the damping force characteristics during extension operation and retraction operation can be set independently.

[0071] That is, the damping force characteristics during extension operation and during retraction operation of the cylinder device C of this embodiment in the damper mode can be adjusted independently by setting the relief valve 43, the extension-side relief valve 25, the first compression-side relief valve 27, and the second compression-side relief valve 33, regardless of the settings of the pressure-receiving area on the rod-side chamber side and the pressure-receiving area on the piston-side chamber side of the piston 4. In other words, when making the two damping force characteristics during extension operation and during retraction operation of the cylinder device C of this embodiment in the damper mode 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 determining the diameter of the rod 3 and the diameter of the piston 4 (diameter of the cylinder 2) arbitrarily within a range permissible in terms of strength, the two damping force characteristics can be adjusted to be the same by setting the relief valve 43, the extension-side relief valve 25, the first compression-side relief valve 27, and the second compression-side relief valve 33.

[0072] Since the damper circuit D of this embodiment is equipped with the extension-side suction passage 30 and the extension-side check valve 31, and allows hydraulic oil to flow from the tank 7 toward the expanding rod-side chamber 5 when the telescopic unit 1 of the cylinder device C in the damper mode retracts, the compression-side passage 32 and the second compression-side relief valve 33 may be omitted. In this case, the settings of the relief valve 43, the extension-side relief valve 25, and the first compression-side relief valve 27 can be adjusted to make the two damping force characteristics identical during extension and retraction of the cylinder device C of this embodiment in the damper mode.

[0073] However, when the compression-side passage 32 and the second compression-side relief valve 33 are provided, if the pressure in the piston-side chamber 6 becomes abnormally high when the telescopic unit 1 in the cylinder device C in the damper mode is contracted, the second compression-side relief valve 33 opens to move the hydraulic oil in the piston-side chamber 6 to the rod-side chamber 5, thereby protecting the cylinder device C, which is an advantage.

[0074] Furthermore, since the damper circuit D of this embodiment is equipped with the compression-side passage 32 and the second compression-side relief valve 33, when the telescopic unit 1 in the cylinder device C in the damper mode contracts, if there is no concern that the rod-side chamber 5 will become negative pressure due to the hydraulic oil supplied from the piston-side chamber 6 to the rod-side chamber 5 through the compression-side passage 32, the extension-side suction passage 30 and the extension-side check valve 31 can be omitted.

[0075] Furthermore, instead of the second compression side relief valve 33, a check valve that does not provide much resistance to the hydraulic oil passing through may be provided in the compression side passage 32, so that when the telescopic unit 1 of the cylinder device C in damper mode is retracted, damping force may be generated only by the resistance of the first compression side relief valve 27. In this case, the damping force characteristics of the damping force generated in relation to the piston speed during extension operation of the cylinder device C in damper mode can be set by the extension side relief valve 25, and the damping force characteristics of the damping force generated in relation to the piston speed during retraction operation of the cylinder device C in damper mode can be set by the first compression side relief valve 27. Therefore, regardless of the settings of the pressure receiving area on the rod side chamber side and the pressure receiving area on the piston side chamber side of the piston 4, the damping force characteristics during extension operation and retraction operation of the cylinder device C in damper mode can be set to the same characteristics.

[0076] As described above, the cylinder device C of this embodiment includes the telescopic unit 1 having the cylinder 2, the rod 3 movably inserted into the cylinder 2, the piston 4 movably inserted into the cylinder 2 and connected to the rod 3 to divide the inside of the cylinder 2 into a rod-side chamber 5 and a piston-side chamber 6, the tank 7, the pump 14 capable of supplying hydraulic oil (liquid) from the tank 7 to the cylinder 2, the control passage 40 connecting the rod-side chamber 5 and the tank 7, and the thrust adjustment unit FT provided in the control passage 40, and the actuator circuit A capable of driving the telescopic unit 1 to extend and retract, and the extension-side damper 14 connecting the rod-side chamber 5 and the piston-side chamber 6. a damper circuit D including: a damping passage 24; an extension-side relief valve 25 provided in the extension-side damping passage 24 and providing resistance to the flow of hydraulic oil (liquid) from the rod-side chamber 5 to the piston-side chamber 6; a compression-side damping passage 26 connecting the piston-side chamber 6 to the thrust adjustment unit FT; a first compression-side relief valve (compression-side relief valve) 27 provided in the compression-side damping passage 26 and providing resistance to the flow of hydraulic oil (liquid) from the piston-side chamber 6 to the tank 7; a suction passage 28 connecting the tank 7 and the piston-side chamber 6; and a suction check valve 29 provided in the suction passage 28 and allowing the flow of hydraulic oil (liquid) from the tank 7 to the piston-side chamber 6.

[0077] The cylinder device C of this embodiment configured in this manner can function as an actuator by supplying hydraulic oil (liquid) from the pump 14 to the cylinder 2 via the actuator circuit A, and can also function as a damper by stopping the pump 14 and using the damper circuit D.

[0078] When the cylinder device C of this embodiment functions as a damper, it generates a damping force by utilizing the extension side relief valve 25 when the telescopic unit 1 is extended, and generates a damping force by utilizing the first compression side relief valve (compression side relief valve) 27 when the telescopic unit 1 is retracted. Therefore, when the cylinder device C of this embodiment functions as a damper, the damping force characteristics during extension and retraction can be set to the same characteristics by configuring the extension side relief valve 25 and the first compression side relief valve (compression side relief valve) 27, regardless of the settings of the diameter of the rod 3 and the diameter of the piston 4 (diameter of the cylinder 2).

[0079] In other words, with the cylinder device C of this embodiment, even if the diameter of the rod 3 is reduced within the range of strength permissible instead of increasing the diameter of the cylinder 2, the damping force characteristics during extension and contraction can be set to be the same when functioning as a damper. If the diameter of the rod 3 is reduced within the range of strength permissible instead of increasing the diameter of the cylinder 2, the pressure-receiving 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 increased. Therefore, the cylinder device C of this embodiment can increase the damping coefficient and generate a high damping force with good responsiveness when functioning as a damper. Therefore, the cylinder device C of this embodiment can improve the damping coefficient when functioning as a damper while still functioning as an actuator without increasing its size.

[0080] In the cylinder device C of the first embodiment, the thrust adjustment section FT has an adjustment passage P1 and a bypass passage P2 provided in parallel in the middle of the control passage 40, a variable relief valve 41 provided in the adjustment passage P1, and a relief valve 43 and a bypass passage opening / closing valve 44 provided in series in this order from the rod-side chamber 5 side in the bypass passage P2, and the compression-side damping passage 26 connects the piston-side chamber 6 between the relief valve 43 and the bypass passage opening / closing valve 44 of the bypass passage P2, and the variable relief valve 41 and the bypass passage opening / closing valve 44 are The variable relief valve 41 is an electromagnetic valve driven by the same solenoid Sol, and its opening pressure can be adjusted when the solenoid Sol is energized. The bypass passage opening / closing valve 44 closes when the solenoid Sol is energized and opens when the solenoid Sol is not energized. In an actuator mode in which the pump 14 is driven, the bypass passage opening / closing valve 44 closes to block the bypass passage P2, and in a damper mode in which the pump 14 is stopped, the bypass passage opening / closing valve 44 opens to open the bypass passage P2.

[0081] The cylinder device C of this embodiment configured as described above can function as an actuator by supplying hydraulic oil (liquid) from the pump 14 to the cylinder 2 via the actuator circuit A and blocking the compression side damping passage 26 with the bypass passage opening / closing valve 44, and can also function as a damper by stopping the pump 14 and opening the compression side damping passage 26 with the bypass passage opening / closing valve 44 and using the damper circuit D.

[0082] When the cylinder device C of this embodiment functions as a damper, it generates a damping force by the extension side relief valve 25 when the telescopic unit 1 is extended, and generates a damping force by the first compression side relief valve (compression side relief valve) 27 when the telescopic unit 1 is retracted. Therefore, when the cylinder device C of this embodiment functions as a damper, the damping force characteristics during extension and retraction can be set to the same characteristics by setting the extension side relief valve 25 and the first compression side relief valve (compression side relief valve) 27, regardless of the settings of the diameter of the rod 3 and the diameter of the piston 4 (diameter of the cylinder 2).

[0083] In other words, with the cylinder device C of this embodiment, even if the diameter of the rod 3 is reduced within the range of strength permissible instead of increasing the diameter of the cylinder 2, the damping force characteristics during extension and contraction can be set to be the same when functioning as a damper. If the diameter of the rod 3 is reduced within the range of strength permissible instead of increasing the diameter of the cylinder 2, the pressure-receiving 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 increased. Therefore, the cylinder device C of this embodiment can increase the damping coefficient and generate a high damping force with good responsiveness when functioning as a damper. Therefore, the cylinder device C of this embodiment can improve the damping coefficient when functioning as a damper while still functioning as an actuator without increasing its size. Incidentally, even if the cross-sectional area of ​​the rod 3 is set to half the cross-sectional area of ​​the piston 4 as in a uniflow damper, if the compression-side passage 32 and the second compression-side relief valve 33 are provided, the pressure in the piston-side chamber 6 when the cylinder device C is contracted can be made higher than the pressure in the rod-side chamber 5, so the damping coefficient during contraction operation can be made higher than in conventional cylinder devices. Therefore, if the compression-side passage 32 and the second compression-side relief valve 33 are provided, the degree of freedom in setting the cross-sectional area of ​​the rod 3 and the cross-sectional area of ​​the piston 4 is improved.

[0084] Furthermore, in the cylinder device C of the present embodiment, when it becomes impossible to energize the motor 15 of the cylinder device C and the valves 11, 13, 41, 44 which are solenoid valves, the bypass passage opening / closing valve 44 automatically opens the compression side damping passage 26, and the cylinder device C switches to the damper mode. Therefore, according to the cylinder device C of the present embodiment, in the event of a malfunction, the damper circuit D is automatically enabled and the mode is switched to the damper mode, and vibration of the carbody S of the railway vehicle T can be suppressed even in the event of a malfunction.

[0085] In the cylinder device C of this embodiment, the damper circuit D includes an extension-side suction passage 30 that communicates the tank 7 and the rod-side chamber 5, and an extension-side check valve 31 that is provided in the extension-side suction passage 30 and allows only the flow of hydraulic oil (liquid) from the tank 7 to the rod-side chamber 5. With the cylinder device C configured in this way, when the telescopic unit 1 retracts, the pressure inside the rod-side chamber 5 does not become negative, and this prevents aeration and a delay in the generation of damping force when the telescopic unit 1 switches from retraction to extension.

[0086] Furthermore, in the cylinder device C of the present embodiment, the actuator circuit A is capable of adjusting the valve opening pressure and has the variable relief valve 41 that adjusts the pressure of the hydraulic oil (liquid) supplied from the pump 14 into the cylinder 2 by adjusting the valve opening pressure, and the valve opening pressure of the extension-side relief valve 25 is higher than the maximum valve opening pressure that the variable relief valve 41 can attain in the actuator mode. In the cylinder device C configured in this way, when it functions as an actuator, the hydraulic oil (liquid) supplied from the pump 14 into the cylinder 2 is not allowed to escape from the rod-side chamber 5 to the piston-side chamber 6, so that it can efficiently generate a contraction-side thrust and also reduces energy consumption.

[0087] <Second embodiment> As shown in Fig. 3, the cylinder device C1 in the second embodiment is configured to include an extension unit 1, a tank 7, an actuator circuit A1, and a damper circuit D1. In this embodiment, two cylinder devices C1 are installed in parallel between the car body S and the bogie B of the railway vehicle T, similar to the cylinder device C, to suppress horizontal vibration of the car body S, but only one cylinder device C1 may be installed between the car body S and the bogie B.

[0088] The various components of the cylinder device C1 will be described below. The extension unit 1 of the cylinder device C1 has the same configuration as the extension unit 1 of the cylinder device C.

[0089] The actuator circuit A1 is provided between the cylinder 2 and the tank 7, and includes a pump 14 capable of supplying hydraulic oil from the tank 7 to the cylinder 2, and is a circuit that drives the extension and retraction of the telescopic unit 1. By driving the pump 14, the actuator circuit A supplies hydraulic oil into the cylinder 2 to select either the extension direction or the retraction direction, causing the telescopic unit 1 to generate thrust in the selected direction and can also adjust the thrust.

[0090] Specifically, as shown in FIG. 3 , the actuator circuit A is provided between the cylinder 2 and the tank 7, and includes a pump 14 that supplies hydraulic oil to the rod-side chamber 5, a motor 15 that drives the pump 14, a control passage 40 that connects the rod-side chamber 5 and the tank 7, a thrust adjustment unit FT1 provided in the control passage 40, a first passage 10 that connects the rod-side chamber 5 and the piston-side chamber 6, a first on-off valve 11 provided in the first passage 10, a second passage 12 that connects the piston-side chamber 6 and the tank 7, and a second on-off valve 13 provided in the second passage 12.

[0091] The actuator circuit A1 in the cylinder device C1 of the second embodiment and the actuator circuit A in the cylinder device C of the first embodiment differ only in the configuration of the thrust adjustment section FT1, and otherwise have the same configuration.

[0092] In the cylinder device C1 of the second embodiment, the rod side chamber 5 and the tank 7 are connected through a control passage 40, and a thrust adjustment unit FT1 is provided in the middle of the control passage 40. The thrust adjustment unit FT1 includes an adjustment passage P3 provided in the middle of the control passage 40, a relief valve 46 that opens when the pressure on the rod side chamber 5 side reaches a valve opening pressure, and a variable relief valve 46 that can adjust the valve opening pressure by energizing. 47 A relief valve 46 and a variable relief valve 47 are provided in series in this order from the rod side chamber 5 side in the adjustment passage P3.

[0093] The relief valve 46 includes a valve element 46a provided in the adjustment passage P3, a spring 46b that biases the valve element 46a so as to close the adjustment passage P3, and a pilot passage 46c that causes the pressure on the rod-side chamber 5 side, which is upstream of the valve element 46a, to act on the valve element 46a in the valve-opening direction against the force of the spring 46b. The valve-opening pressure of the relief valve 46 is set in advance to a predetermined valve-opening pressure by the force of the spring 46b that biases the valve element 46a.

[0094] The variable relief valve 47 is configured to include a valve element 47a provided in the adjustment passage P3, a spring 47b that biases the valve element 47a so as to close the adjustment passage P3, a pilot passage 47c that causes the pressure on the rod-side chamber 5 side, which is upstream of the valve element 47a, to act on the valve element 47a in the valve opening direction against the force of the spring 47b, and a solenoid 47d that generates a thrust force against the spring 47b when energized. 47 is a solenoid valve whose valve opening pressure can be adjusted by adjusting the amount of current flowing through the solenoid 47d.

[0095] Then, when the pressure acting on the valve body 47a upstream of the variable relief valve 47 in the adjustment passage P3 and downstream of the relief valve 46 exceeds the relief pressure (valve opening pressure) of the variable relief valve 47, the force of this pressure and the solenoid 47d pressing on the valve body 47a overcomes the biasing force of the spring 47b biasing the valve body 47a, causing the valve body 47a to move backward and the variable relief valve 47 to open the adjustment passage P3.

[0096] Furthermore, in the adjustable relief valve 47, increasing the amount of current supplied to the solenoid 47d can increase the thrust generated by the solenoid 47d. Therefore, when the amount of current supplied to the solenoid 47d is maximized, the valve opening pressure of the adjustable relief valve 47 is minimized, and conversely, when no current is supplied to the solenoid 47d at all, the valve opening pressure of the adjustable relief valve 47 is maximized.

[0097] Next, the damper circuit D1 includes an extension-side damping passage 24 communicating between the rod-side chamber 5 and the piston-side chamber 6, an extension-side relief valve 25 provided in the extension-side damping passage 24 and providing resistance to the flow of hydraulic oil from the rod-side chamber 5 toward the piston-side chamber 6, a compression-side damping passage 26 connecting the piston-side chamber 6 and the thrust adjustment unit FT1, a first compression-side relief valve 27 provided in the compression-side damping passage 26 and serving as a compression-side relief valve providing resistance to the flow of hydraulic oil from the piston-side chamber 6 toward the tank 7, and a suction passage 28 communicating between the tank 7 and the piston-side chamber 6. a suction check valve 29 provided in the suction passage 28 to allow the flow of hydraulic oil from the tank 7 to the piston-side chamber 6; an extension-side suction passage 30 communicating between the tank 7 and the rod-side chamber 5; an extension-side check valve 31 provided in the extension-side suction passage 30 to allow only the flow of hydraulic oil from the tank 7 to the rod-side chamber 5; a compression-side passage 32 communicating between the piston-side chamber 6 and the rod-side chamber 5; and a second compression-side relief valve 33 provided in the compression-side passage 32 to provide resistance to the flow of hydraulic oil from the piston-side chamber 6 to the rod-side chamber 5.

[0098] The damper circuit D1 in the cylinder device C1 of the second embodiment and the damper circuit D in the cylinder device C of the first embodiment differ in that the compression side damping passage 26 is connected between the relief valve 46 and the variable relief valve 47 of the adjustment passage P3 in the thrust adjustment section FT1, but otherwise have the same configuration.

[0099] As described above, the compression side damping passage 26 is connected to the thrust adjustment unit FT1. However, unlike the cylinder device C of the first embodiment, no opening / closing valve is provided in the adjustment passage P3 of the thrust adjustment unit FT1. Therefore, the communication between the compression side damping passage 26 and the tank 7 is not interrupted.

[0100] The cylinder device C1 is configured as described above, and the operation of the cylinder device C1 will be described below. First, the actuator mode in which the cylinder device C1 functions as an actuator using the actuator circuit A1 will be described. When generating thrust in the extension direction in the cylinder device C1, the first on-off valve 11 is set to the communicating position 11b, the second on-off valve 13 is set to the blocking position 13c, and the pump 14 is driven by the motor 15 to supply hydraulic oil from the tank 7 to the cylinder 2. In addition, the amount of current supplied to the solenoid 47d is adjusted to adjust the valve opening pressure of the variable relief valve 47 according to the thrust to be generated by the cylinder device C1.

[0101] In this way, when the first on-off valve 11 is opened, the rod side chamber 5 and the piston side chamber 6 are placed in a state of communication through the first passage 10, and hydraulic oil is supplied from the pump 14 to the rod side chamber 5 and the piston side chamber 6.

[0102] Therefore, when the first on-off valve 11 is set to the communication position 11b and the second on-off valve 13 is set to the shut-off position 13c and the pump 14 is driven by the motor 15, the hydraulic oil supplied from the pump 14 into the cylinder 2 presses the piston 4 against the cylinder 2 in a direction that pushes it out to the left in Figure 1, and the cylinder device C1 generates thrust in the extension direction.

[0103] In the cylinder device C1 of the second embodiment, the compression side damping passage 26 is not blocked by an on-off valve. Therefore, the hydraulic oil supplied into the cylinder 2 can move from the rod side chamber 5 to the tank 7 via the control passage 40 and thrust adjustment unit FT1, and can also move from the piston side chamber 6 to the tank 7 via the compression side damping passage 26, the first compression side relief valve 27, and thrust adjustment unit FT1.

[0104] Then, when both the pressure in the rod side chamber 5 and the pressure in the piston side chamber 6, which is connected to the rod side chamber 5 by the first passage 10, exceed the valve opening pressures of the relief valve 46 and the first compression side relief valve 27 and the variable relief valve 47 opens, the hydraulic oil in the rod side chamber 5 moves to the tank 7 via the control passage 40 and the adjustment passage P3, and the hydraulic oil in the piston side chamber 6 moves to the tank 7 via the compression side damping passage 26 and the adjustment passage P3.

[0105] In other words, when the first on-off valve 11 is in the communication position 11b and the second on-off valve 13 is in the shut-off position 13c, the relief valve 46 and the first compression side relief valve 27 are arranged in parallel between the cylinder 2 and the tank 7, and the variable relief valve 47 is arranged downstream of these relief valves 46 and the first compression side relief valve 27.

[0106] When the first on-off valve 11 is in the communicating position 11b and the second on-off valve 13 is in the shutoff position 13c, if hydraulic oil is supplied from the pump 14 into the cylinder 2 and an excess of hydraulic oil occurs in the cylinder 2, the hydraulic oil forced out of the cylinder 2 passes through one or both of the relief valve 46 and the first compression side relief valve 27, and then necessarily passes through the adjustable relief valve 47 and moves to the tank 7, so that the pressure in the cylinder 2 can be adjusted by adjusting the valve opening pressure of the adjustable relief valve 47. Thus, in the cylinder device C1 of the second embodiment, when the first on-off valve 11 is in the communicating position 11b and the second on-off valve 13 is in the shutoff position 13c, the relief valve 46, the first compression side relief valve 27, and the adjustable relief valve 47 act as resistance, causing the pressure in the cylinder 2 to increase and causing the cylinder device C1 to generate thrust in the extension direction.

[0107] As described above, when the first on-off valve 11 is in the communicating position 11b and the second on-off valve 13 is in the shutoff position 13c, the cylinder device C1 of the second embodiment generates a thrust in the extension direction equal to the pressure difference between the pressure-receiving areas of the piston-side chamber and the rod-side chamber of the piston 4 multiplied by the pressure of the rod-side chamber 5, just like the cylinder device C, and the thrust can be adjusted by adjusting the valve opening pressure of the adjustable relief valve 47. In this state, even if the telescopic unit 1 is forcibly retracted by an external force, the pressure in the rod-side chamber 5 and the piston-side chamber 6 is controlled by the adjustable relief valve 47, and a thrust in the extension direction that suppresses the retraction is generated.

[0108] If the telescopic unit 1 contracts at high speed due to an external force while the cylinder device C1 is generating thrust in the extension direction, causing the pressure inside the piston side chamber 6 to become abnormally high, the second compression-side relief valve 33 opens to move the hydraulic oil inside the piston side chamber 6 to the rod-side chamber 5, thereby protecting the cylinder device C1.

[0109] On the other hand, when generating a thrust in the contraction direction in the cylinder device C1, the first on-off valve 11 is set to the shutoff position 11c, the second on-off valve 13 is set to the communication position 13b, and the motor 15 drives the pump 14 to supply hydraulic oil from the tank 7 to the rod-side chamber 5. Also, the amount of current supplied to the solenoid 47d is adjusted to adjust the valve opening pressure of the variable relief valve 47 according to the thrust to be exerted by the cylinder device C1.

[0110] In this manner, the piston-side chamber 6 and the tank 7 are placed in a state of communication through the second passage 12 by opening the second on-off valve 13, and the first on-off valve 11 is closed to cut off communication between the rod-side chamber 5 and the piston-side chamber 6, so that the hydraulic oil discharged from the pump 14 is supplied only to the rod-side chamber 5. Furthermore, in the cylinder device C1, the compression-side damping passage 26 is not blocked by an on-off valve, but in a state in which the piston-side chamber 6 and the tank 7 are connected by the second passage 12, when the cylinder device C1 contracts, the hydraulic oil moves from the piston-side chamber 6 to the tank 7 through only the second passage 12.

[0111] Therefore, when the first on-off valve 11 is set to the shutoff position 11c and the second on-off valve 13 is set to the communication position 13b and the pump 14 is driven by the motor 15, the hydraulic oil supplied from the pump 14 to the rod side chamber 5 presses the piston 4 toward the right in FIG. 1 relative to the cylinder 2, and the cylinder device C1 generates thrust in the contraction direction.

[0112] In the cylinder device C1 of the second embodiment, when the first on-off valve 11 is in the shutoff position 11c and the second on-off valve 13 is in the communicating position 13b and the pump 14 is driven by the motor 15, hydraulic oil is supplied only to the rod-side chamber 5. If there is an excess of hydraulic oil in the rod-side chamber 5, the hydraulic oil pushed out from the rod-side chamber 5 passes through the relief valve 46 and the adjustable relief valve 47 and moves to the tank 7, so that the pressure in the cylinder 2 can be adjusted by adjusting the valve opening pressure of the adjustable relief valve 47. Therefore, in the cylinder device C1 of the second embodiment, when the first on-off valve 11 is in the shutoff position 11c and the second on-off valve 13 is in the communicating position 13b, the relief valve 46 and the adjustable relief valve 47 act as resistance, causing the pressure in the cylinder 2 to increase and causing the cylinder device C1 to generate thrust in the contraction direction.

[0113] As described above, the cylinder device C1 of the second embodiment has the first on-off valve 11. Shut-off position 13c The second on-off valve 13 Communication position 11b In this case, similarly to the cylinder device C, the pressure-receiving area of ​​the piston 4 on the rod side chamber side is The value multiplied by the opening pressure of the variable relief valve 47 is A thrust in the contraction direction is generated that is equal to the value obtained by subtracting the product of the pressure-receiving area on the piston side chamber side and the pressure in the tank 7, and the thrust can be adjusted by adjusting the valve opening pressure of the adjustable relief valve 47. In this state, even if the telescopic unit 1 is forcibly extended by an external force, the pressure in the rod side chamber 5 is controlled by the adjustable relief valve 47, so a thrust in the contraction direction that suppresses the extension is generated.

[0114] In addition, when generating a thrust in the contraction direction in the cylinder device C1 of the present embodiment, as described above, it is necessary to supply hydraulic oil to the rod-side chamber 5 in a state in which communication between the rod-side chamber 5 and the piston-side chamber 6 is cut off. Here, the extension-side damping passage 24 in the damper circuit D1 allows hydraulic oil to flow from the rod-side chamber 5 to the piston-side chamber 6 when the extension-side relief valve 25 opens.

[0115] Therefore, when generating a thrust in the contraction direction in the cylinder device C1 of this embodiment, if the extension-side relief valve 25 opens, hydraulic oil will escape from the rod-side chamber 5 to the piston-side chamber 6, resulting in poor efficiency. However, the valve opening pressure of the extension-side relief valve 25 is set to be equal to or greater than the difference between the pressure in the rod-side chamber 5 and the pressure in the piston-side chamber 6 when the actuator circuit A1 causes the telescopic unit 1 to generate a maximum thrust in the contraction direction. The maximum thrust in the contraction direction of the cylinder device C1 in the actuator mode is generated when the valve opening pressure of the adjustable relief valve 47 is maximized. Therefore, when the cylinder device C1 of this embodiment functions as an actuator that generates a thrust in the contraction direction, the extension-side relief valve 25 does not open even if the valve opening pressure of the adjustable relief valve 47 is maximized, thereby preventing hydraulic oil from moving from the rod-side chamber 5 to the piston-side chamber 6 through the extension-side damping passage 24. In this way, when the valve opening pressure of the extension-side relief valve 25 is set to be equal to or greater than the difference between the pressure in the rod-side chamber 5 and the pressure in the piston-side chamber 6 when the telescopic unit 1 generates a maximum thrust toward the retraction side by the actuator circuit A1, the cylinder device C1 can efficiently generate thrust in the retraction direction when generating thrust as an actuator, and energy consumption is reduced. As described above, in the cylinder device C1 of this embodiment, the extension-side relief valve 25 does not need to open even when the variable relief valve 47, which controls the pressure in the rod-side chamber 5, reaches its maximum valve opening pressure. Therefore, the valve opening pressure of the extension-side relief valve 25 only needs to be higher than the pressure loss generated by the relief valves 46 and 47 when the variable relief valve 47 is set to its maximum valve opening pressure, i.e., the pressure loss generated in the thrust adjustment unit FT1. In this case, the valve opening pressure of the extension-side relief valve 25 may be higher than the maximum pressure loss that the thrust adjustment unit FT1 can control in the actuator mode, rather than the maximum pressure loss in the hardware of the thrust adjustment unit FT1.

[0116] As mentioned above, from the viewpoint of efficiency, it is advisable to set the valve opening pressure of the extension-side relief valve 25 to be equal to or greater than the difference between the pressure in the rod-side chamber 5 and the pressure in the piston-side chamber 6 when the telescopic unit 1 generates the maximum thrust to the contraction side by the actuator circuit A1. However, even if the valve opening pressure is set to be less than the difference, the cylinder device C1 can generate thrust in the contraction direction as an actuator.

[0117] If the telescopic unit 1 is extended at high speed by an external force while the cylinder device C1 is generating thrust in the contraction direction, causing the pressure in the rod-side chamber 5 to become abnormally high, the extension-side relief valve 25 opens to move the hydraulic oil in the rod-side chamber 5 to the piston-side chamber 6, thereby protecting the cylinder device C1.

[0118] In this way, the cylinder device C1 can generate thrust within an adjustable range in both the extension direction and the contraction direction by opening and closing the first on-off valve 11 and the second on-off valve 13 and adjusting the valve opening pressure of the variable relief valve 47. Therefore, in the actuator mode, the cylinder device C1 operates the first on-off valve 11, the second on-off valve 13, and the variable relief valve 47 while driving the pump 14. 47 By controlling the above, the cylinder device C1 can function as an actuator to suppress vibration of the vehicle body S.

[0119] Next, a damper mode in which the damper circuit D1 is used to cause the cylinder device C to function as a damper will be described. When the cylinder device C1 is in the damper mode, the first on-off valve 11 is set to the shut-off position 11c, the second on-off valve 13 is set to the shut-off position 13c, the motor 15 is not driven, and the pump 14 is stopped. In addition, the solenoid 47d may be energized or de-energized.

[0120] In this state, communication between the rod-side chamber 5 and the piston-side chamber 6 through the first passage 10 is cut off, and communication between the piston-side chamber 6 and the tank 7 through the second passage 12 is cut off. Even in the damper mode in which the cylinder device C1 functions as a damper in this way, the compression-side damping passage 26 is connected to the tank 7 via the variable relief valve 47 in the thrust adjustment unit FT1.

[0121] When the telescopic unit 1 is extended by an external force with the cylinder device C1 in the damper mode, the piston 4 moves leftward in FIG. 1 relative to the cylinder 2, contracting the rod-side chamber 5 and expanding the piston-side chamber 6. The hydraulic oil in the contracting rod-side chamber 5 passes through either the thrust adjustment unit FT1 or the extension-side relief valve 25 of the extension-side damping passage 24, or both, and moves to the tank 7 or the expanding piston-side chamber 6 while being resisted by either the thrust adjustment unit FT1 or the extension-side relief valve 25. When the telescopic unit 1 is extended, the rod 3 retracts from the cylinder 2, causing a shortage of hydraulic oil in the cylinder 2. However, the suction check valve 29 opens, and the shortage of hydraulic oil is supplied from the tank 7 to the piston-side chamber 6 through the suction passage 28. In this way, when the cylinder device C1 is in the damper mode and the telescopic unit 1 is extended, the pressure in the rod-side chamber 5 increases due to the thrust adjustment unit FT1 and the extension-side relief valve 25, and the pressure in the piston-side chamber 6 becomes equal to the tank pressure. Therefore, the cylinder device C1 generates a damping force in a direction that hinders the extension of the telescopic unit 1, the damping force being equal to the value obtained by multiplying the pressure-receiving area on the rod-side chamber side of the piston 4 by the pressure in the rod-side chamber 5 minus the value obtained by multiplying the pressure-receiving area on the piston-side chamber side of the piston 4 by the pressure in the tank 7.

[0122] Furthermore, when the telescopic unit 1 is contracted by an external force with the cylinder device C1 in the damper mode, the piston 4 moves to the right in FIG. 1 relative to the cylinder 2, contracting the piston-side chamber 6 and expanding the rod-side chamber 5. The hydraulic oil in the contracting piston-side chamber 6 passes through the second compression-side relief valve 33 of the compression-side passage 32 and moves to the expanding rod-side chamber 5. When the telescopic unit 1 is contracted, the rod 3 enters the cylinder 2, causing an excess of hydraulic oil in the cylinder 2. However, the first compression-side relief valve 27 and the adjustable relief valve 47 open, and the excess hydraulic oil is discharged from the piston-side chamber 6 to the tank 7 through the compression-side damping passage 26, the adjustment passage P3, and the control passage 40. In this way, when the cylinder device C1 is in the damper mode and the telescopic unit 1 is contracted, the pressure in the piston side chamber 6 is increased by the first compression-side relief valve 27, the variable relief valve 47, and the second compression-side relief valve 33, the pressure in the rod side chamber 5 is reduced, and the pressure in the piston side chamber 6 becomes higher than the pressure in the rod-side chamber 5. Therefore, the cylinder device C1 generates a damping force in a direction that prevents the contraction of the telescopic unit 1, equal to the value obtained by multiplying the pressure-receiving area on the piston side chamber side of the piston 4 by the pressure in the piston side chamber 6 minus the value obtained by multiplying the pressure-receiving area on the rod side chamber side of the piston 4 by the pressure in the rod-side chamber 5. In the cylinder device C1 of this embodiment, since the damper circuit D1 is equipped with the extension-side suction passage 30 and the extension-side check valve 31, when the telescopic unit 1 is contracted in the cylinder device C1 in the damper mode, if the pressure in the rod-side chamber 5 becomes lower than the tank pressure, the extension-side check valve 31 opens and hydraulic oil is supplied from the tank 7 to the rod-side chamber 5. Therefore, when the cylinder device C1 of this embodiment contracts in the damper mode, the pressure inside the rod side chamber 5 does not become negative, and aeration or a delay in the generation of the damping force when the telescopic unit 1 switches from contraction to extension is avoided.

[0123] In this way, in the damper mode, when the telescopic unit 1 is extended or retracted by an external force, the cylinder device C1 generates a damping force that hinders the extension or retraction of the telescopic unit 1. In the damper mode, the cylinder device C1 generates a damping force by one or both of the thrust adjustment unit FT1 and the extension-side relief valve 25 when the telescopic unit 1 is extended, and generates a damping force by the first compression-side relief valve 27, the variable relief valve 47, and the second compression-side relief valve 33 when the telescopic unit 1 is retracted. Therefore, the damping force characteristics of the damping force generated in response to the piston speed during extension operation of the cylinder device C1 in the damper mode are set by the relief valve 46 and the variable relief valve 47 in the thrust adjustment unit FT1 and the extension-side relief valve 25, and the damping force characteristics of the damping force generated in response to the piston speed during contraction operation of the cylinder device C1 in the damper mode are set by the first compression-side relief valve 27 and the variable relief valve 47 and the second compression-side relief valve 33, so that the damping force characteristics during extension operation and contraction operation can be set independently.

[0124] That is, the damping force characteristics of the cylinder device C of this embodiment in the damper mode during extension and contraction can be independently adjusted by the settings of the relief valve 46, the variable relief valve 47, the extension-side relief valve 25, the first compression-side relief valve 27, and the second compression-side relief valve 33, regardless of the settings of the pressure-receiving area on the rod-side chamber side and the pressure-receiving area on the piston-side chamber side of the piston 4. In other words, the cylinder device C1 of this embodiment in the damper mode Growth When making the two damping force characteristics during long operation and during retraction operation identical, it is not necessary to make the cross-sectional area of ​​the rod 3 half that of the piston 4. The diameters of the rod 3 and the piston 4 (diameter of the cylinder 2) can be arbitrarily determined within a range permissible in terms of strength, and then the relief valve 46, the variable relief valve 47, the extension side relief valve 25, the first compression side relief valve 27, and the second compression side relief valve 33 can be set to adjust the two damping force characteristics to be identical.

[0125] Since the damper circuit D1 of this embodiment includes the extension-side suction passage 30 and the extension-side check valve 31, and allows hydraulic oil to flow from the tank 7 toward the expanding rod-side chamber 5 when the telescopic unit 1 of the cylinder device C1 in the damper mode retracts, the compression-side passage 32 and the second compression-side relief valve 33 may be omitted. In this case, the two damping force characteristics during extension and retraction of the cylinder device C1 of this embodiment in the damper mode can be adjusted to be the same by setting the relief valve 46, the variable relief valve 47, the extension-side relief valve 25, and the first compression-side relief valve 27.

[0126] However, when the compression-side passage 32 and the second compression-side relief valve 33 are provided, if the pressure in the piston-side chamber 6 becomes abnormally high when the telescopic unit 1 in the cylinder device C1 in the damper mode is contracted, the second compression-side relief valve 33 opens to move the hydraulic oil in the piston-side chamber 6 to the rod-side chamber 5, thereby protecting the cylinder device C1.

[0127] Furthermore, since the damper circuit D1 of the present embodiment is equipped with the compression-side passage 32 and the second compression-side relief valve 33, when the telescopic unit 1 in the cylinder device C1 in the damper mode contracts, if there is no concern that the rod-side chamber 5 will become negative pressure due to the hydraulic oil supplied from the piston-side chamber 6 to the rod-side chamber 5 through the compression-side passage 32, the extension-side suction passage 30 and the extension-side check valve 31 can be omitted.

[0128] Furthermore, instead of the second compression side relief valve 33, a check valve that does not provide much resistance to the hydraulic oil passing through may be provided in the compression side passage 32, and when the telescopic unit 1 in the cylinder device C1 in the damper mode contracts, a damping force may be generated by the resistance of the first compression side relief valve 27 and the variable relief valve 47. In this case, the damping force characteristics of the damping force generated in relation to the piston speed during the extension operation of the cylinder device C1 in the damper mode may be controlled by the extension side relief valve 25. , relief valve 46 and variable relief valve 47The damping force characteristics of the damping force generated in relation to the piston speed during the contraction operation of the cylinder device C in the damper mode can be set by the first compression side relief valve 27 and the variable relief valve 47. Therefore, regardless of the settings of the pressure receiving area on the rod side chamber side and the pressure receiving area on the piston side chamber side of the piston 4, the damping force characteristics during the extension operation and the contraction operation of the cylinder device C1 in the damper mode can be set to the same characteristics.

[0129] As described above, the cylinder device C1 of this embodiment includes the telescopic unit 1 having the cylinder 2, the rod 3 movably inserted into the cylinder 2, the piston 4 movably inserted into the cylinder 2 and connected to the rod 3 to divide the inside of the cylinder 2 into a rod-side chamber 5 and a piston-side chamber 6, the tank 7, the pump 14 capable of supplying hydraulic oil (liquid) from the tank 7 to the cylinder 2, the control passage 40 connecting the rod-side chamber 5 and the tank 7, and the thrust adjustment unit FT1 provided in the control passage 40, and the actuator circuit A1 capable of driving the telescopic unit 1 to telescope and extend; The damper circuit D1 includes a damping passage 24, an extension-side relief valve 25 that is provided in the extension-side damping passage 24 and provides resistance to the flow of hydraulic oil (liquid) from the rod-side chamber 5 to the piston-side chamber 6, a compression-side damping passage 26 that connects the piston-side chamber 6 to the thrust adjustment unit FT1, a first compression-side relief valve (compression-side relief valve) 27 that is provided in the compression-side damping passage 26 and provides resistance to the flow of hydraulic oil (liquid) from the piston-side chamber 6 to the tank 7, a suction passage 28 that connects the tank 7 and the piston-side chamber 6, and a suction check valve 29 that is provided in the suction passage 28 and allows the flow of hydraulic oil (liquid) from the tank 7 to the piston-side chamber 6.

[0130] The cylinder device C1 of this embodiment configured in this manner can function as an actuator by supplying hydraulic oil (liquid) from the pump 14 to the cylinder 2 via the actuator circuit A1, and can also function as a damper by stopping the pump 14 and using the damper circuit D1.

[0131] When the cylinder device C1 of this embodiment functions as a damper, it generates a damping force by utilizing the extension side relief valve 25 when the telescopic unit 1 is extended, and generates a damping force by utilizing the first compression side relief valve (compression side relief valve) 27 when the telescopic unit 1 is retracted. Therefore, when the cylinder device C1 of this embodiment functions as a damper, the damping force characteristics during extension and retraction can be set to the same characteristics by configuring the extension side relief valve 25 and the first compression side relief valve (compression side relief valve) 27, regardless of the settings of the diameter of the rod 3 and the diameter of the piston 4 (diameter of the cylinder 2).

[0132] In other words, with the cylinder device C1 of this embodiment, even if the diameter of the rod 3 is reduced within the range of strength permissible instead of increasing the diameter of the cylinder 2, the damping force characteristics during extension and contraction can be set to be the same when functioning as a damper. If the diameter of the rod 3 is reduced within the range of strength permissible instead of increasing the diameter of the cylinder 2, the pressure-receiving 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 increased. Therefore, the cylinder device C1 of this embodiment can increase the damping coefficient and generate a high damping force with good responsiveness when functioning as a damper. Therefore, the cylinder device C1 of this embodiment can improve the damping coefficient when functioning as a damper while still functioning as an actuator without increasing its size.

[0133] In the cylinder device C of the first embodiment, the compression side damping passage 26 provided with the first compression side relief valve 27 is connected between the relief valve 43 of the bypass passage P2 provided with the bypass passage on-off valve 44 in the thrust adjustment unit FT and the bypass passage on-off valve 44, and in the actuator mode, the bypass passage on-off valve 44 is shut off to shut off the compression side damping passage 26, but in the cylinder device C1 of the second embodiment, even in the actuator mode, the compression side damping passage 26 is not shut off by an on-off valve, but is connected upstream of the variable relief valve 47 of the thrust adjustment unit FT1, and the first compression side relief valve 27 is used to generate thrust of the cylinder device C1 in the actuator mode. On the other hand, the cylinder device C of the first embodiment and the cylinder device C1 of the second embodiment always generate damping force by utilizing the first compression side relief valve 27 in the damper mode. In this way, the thrust adjustment units FT, FT1 only need to be configured to be able to generate a damping force by utilizing the first compression side relief valve 27 in the damper mode, and in the actuator mode, the compression side damping passage 26 in which the first compression side relief valve 27 is provided may be completely blocked as in the cylinder device C of the first embodiment, or the compression side damping passage 26 may be open and not blocked as in the cylinder device C1 of the second embodiment.

[0134] That is, in the case where only one adjustment passage P3 equipped with a variable relief valve 47 capable of adjusting thrust is provided, as in the thrust adjustment unit FT1 of the second embodiment, the compression side damping passage 26 may be connected upstream of the variable relief valve 47. Also, in the case where the thrust adjustment unit FT of the first embodiment is provided with an adjustment passage P1 equipped with a variable relief valve 41 capable of adjusting thrust and a bypass passage P2 equipped with a bypass passage opening / closing valve 44 that opens in the damper mode, the compression side damping passage 26 may be connected upstream of the bypass passage opening / closing valve 44 of the bypass passage P2 that is active in the damper mode. Furthermore, the thrust adjustment units FT and FT1 may be provided with three or more parallel passages, and the compression side damping passage 26 may be connected upstream of the variable relief valve or opening / closing valve of a passage provided with the variable relief valve or opening / closing valve. As described above, the thrust adjustment units FT, FT1 can adjust the thrust of the cylinder devices C, C1 by controlling the pressure in the cylinder 2, which is upstream, in the actuator mode, and only need to be provided with a passage that is provided with a variable relief valve or an on-off valve and is open in the damper mode, and the compression side damping passage 26 only needs to be connected upstream of the variable relief valve or on-off valve of the passage that is open in the damper mode.

[0135] Moreover, in the cylinder device C1 of the second embodiment, the thrust adjustment unit FT1 includes an adjustment passage P3 provided in the middle of the control passage 40, a relief valve 46 that opens when the pressure on the rod-side chamber 5 side reaches a valve opening pressure, and a variable relief valve 47 that can adjust the valve opening pressure by energizing, and the relief valve 46 and the variable relief valve 47 are arranged in series in this order from the rod-side chamber 5 side in the adjustment passage P3, and the compression-side damping passage 26 connects the piston-side chamber 6 between the relief valve 46 and the variable relief valve 47 of the adjustment passage P3.

[0136] The cylinder device C1 of the present embodiment configured as described above does not have an on-off valve in the thrust adjustment unit FT1 that blocks the compression side damping passage 26 in the actuator mode, but can generate a compression side damping force by utilizing the first compression side relief valve 27 in the damper mode. This simplifies the configuration of the thrust adjustment unit FT1 and does not require an on-off valve, thereby reducing the manufacturing cost of the cylinder device C1.

[0137] When the cylinder device C1 of this embodiment functions as a damper, it generates a damping force by the extension side relief valve 25 when the telescopic unit 1 is extended, and generates a damping force by the first compression side relief valve (compression side relief valve) 27 when the telescopic unit 1 is retracted. Therefore, when the cylinder device C1 of this embodiment functions as a damper, the damping force characteristics during extension and retraction can be set to the same characteristics by setting the extension side relief valve 25 and the first compression side relief valve (compression side relief valve) 27, regardless of the settings of the diameter of the rod 3 and the diameter of the piston 4 (diameter of the cylinder 2).

[0138] In other words, with the cylinder device C1 of this embodiment, even if the diameter of the rod 3 is reduced within the range of strength permissible instead of increasing the diameter of the cylinder 2, the damping force characteristics during extension and contraction can be set to be the same when functioning as a damper. If the diameter of the rod 3 is reduced within the range of strength permissible instead of increasing the diameter of the cylinder 2, the pressure-receiving 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 increased. Therefore, the cylinder device C of this embodiment can increase the damping coefficient and generate a high damping force with good responsiveness when functioning as a damper. Therefore, the cylinder device C1 of this embodiment can improve the damping coefficient when functioning as a damper while functioning as an actuator without increasing its size. Incidentally, even if the cross-sectional area of ​​the rod 3 is set to half the cross-sectional area of ​​the piston 4 as in a uniflow damper, if the compression-side passage 32 and the second compression-side relief valve 33 are provided, the pressure in the piston-side chamber 6 when the cylinder device C1 is contracted can be made higher than the pressure in the rod-side chamber 5, so the damping coefficient during contraction operation can be made higher than in conventional cylinder devices. Therefore, if the compression-side passage 32 and the second compression-side relief valve 33 are provided, the degree of freedom in setting the cross-sectional area of ​​the rod 3 and the cross-sectional area of ​​the piston 4 is improved.

[0139] Furthermore, in the cylinder device C of this embodiment, when it becomes impossible to energize the motor 15 of the cylinder device C and the solenoid valves 11, 13, and 47, the cylinder device C1 automatically switches to the damper mode. Therefore, according to the cylinder device C1 of this embodiment, in the event of a malfunction, the damper circuit D1 is automatically enabled and the mode is switched to the damper mode, and vibration of the carbody S of the railway vehicle T can be suppressed even in the event of a malfunction.

[0140] In the cylinder device C1 of this embodiment, the damper circuit D1 includes an extension-side suction passage 30 that communicates the tank 7 with the rod-side chamber 5, and an extension-side check valve 31 that is provided in the extension-side suction passage 30 and allows only the flow of hydraulic oil (liquid) from the tank 7 toward the rod-side chamber 5. According to the cylinder device C1 configured in this way, when the telescopic unit 1 retracts, the inside of the rod-side chamber 5 does not become negative pressure, and this prevents aeration and a delay in the generation of damping force when the telescopic unit 1 switches from retraction to extension.

[0141] Furthermore, in the cylinder device C1 of the present embodiment, the actuator circuit A1 is capable of adjusting the valve opening pressure and has a variable relief valve 47 that adjusts the pressure inside the cylinder 2 by adjusting the valve opening pressure, and the valve opening pressure of the extension-side relief valve 25 is higher than the maximum pressure loss that the thrust adjustment unit FT1 can achieve in the actuator mode. In the cylinder device C1 configured in this manner, when it functions as an actuator, the hydraulic oil (liquid) supplied from the pump 14 into the cylinder 2 is not allowed to escape from the rod-side chamber 5 to the piston-side chamber 6, so that it can efficiently generate a contraction-side thrust and also reduces energy consumption.

[0142] Although the description of the embodiment of the present invention has been completed above, it goes without saying that the scope of the present invention is not limited to the exact details shown or described. [Explanation of symbols]

[0143] 1 Telescopic unit, 2 Cylinder, 3 Rod, 4 Piston, 5 Rod side chamber, 6 Piston side chamber, 7 Tank, 14 Pump, 24 Rebound side damping passage, 25 Rebound side relief valve, 26 Compression side damping passage, 27 First compression side relief valve (compression side relief valve), 28 Suction passage, 29 Suction check valve, 30 Rebound side suction passage, 3 1···Extension side check valve, 40···Control passage, 41, 47···Adjustable relief valve, 42···Bypass passage, 43, 46···Relief valve, 44···Bypass passage opening / closing valve, A, A1···Actuator circuit, C, C1···Cylinder device, D, D1···Damper circuit, FT, FT1···Thrust adjustment section, P1, P3···Adjustment passage, P2···Bypass path, Sol···Solenoid

Claims

1. an extension unit including a cylinder, a rod movably inserted into the cylinder, and a piston movably inserted into the cylinder and connected to the rod to divide the interior of the cylinder into a rod-side chamber and a piston-side chamber; Tank and an actuator circuit having a pump capable of supplying liquid from the tank to the cylinder, an adjustment passage communicating between the rod side chamber and the tank and having a variable relief valve provided therein, and a bypass passage communicating between the rod side chamber and the tank and having a relief valve and a bypass passage opening / closing valve provided in series therein, and capable of driving the telescopic unit to telescope; a damper circuit including: an extension-side damping passage communicating between the rod-side chamber and the piston-side chamber; an extension-side relief valve provided in the extension-side damping passage and providing resistance to a flow of liquid from the rod-side chamber to the piston-side chamber; a compression-side damping passage connecting the piston-side chamber to a position between the relief valve and the bypass passage opening / closing valve of the bypass passage; a compression-side relief valve provided in the compression-side damping passage and providing resistance to a flow of liquid from the piston-side chamber to the tank; a suction passage communicating between the tank and the piston-side chamber; and a suction check valve provided in the suction passage and allowing a flow of liquid from the tank to the piston-side chamber, the variable relief valve and the bypass passage opening / closing valve are electromagnetic valves driven by the same solenoid, The variable relief valve is capable of adjusting a valve opening pressure when the solenoid is energized, the bypass passage opening / closing valve is closed when the solenoid is energized and is open when the solenoid is not energized; In an actuator mode in which the pump is driven, the bypass passage opening / closing valve is closed to block the bypass passage, and in a damper mode in which the pump is stopped, the bypass passage opening / closing valve is opened to open the bypass passage. A cylinder device characterized by:

2. an extension unit including a cylinder, a rod movably inserted into the cylinder, and a piston movably inserted into the cylinder and connected to the rod to divide the interior of the cylinder into a rod-side chamber and a piston-side chamber; Tank and an actuator circuit including a pump capable of supplying liquid from the tank to the cylinder, a control passage communicating the rod side chamber and the tank, and a thrust adjustment unit provided in the control passage, and capable of driving the telescopic unit to telescope; a damper circuit including: an extension-side damping passage communicating between the rod-side chamber and the piston-side chamber; an extension-side relief valve provided in the extension-side damping passage and providing resistance to a flow of liquid from the rod-side chamber to the piston-side chamber; a compression-side damping passage connecting the piston-side chamber to the thrust adjuster; a compression-side relief valve provided in the compression-side damping passage and providing resistance to a flow of liquid from the piston-side chamber to the tank; a suction passage communicating between the tank and the piston-side chamber; and a suction check valve provided in the suction passage and allowing a flow of liquid from the tank to the piston-side chamber, the thrust adjustment unit includes an adjustment passage provided in the middle of the control passage, a relief valve that opens when the pressure on the rod side chamber side reaches a valve opening pressure, and a variable relief valve that can adjust the valve opening pressure by energizing, and the relief valve and the variable relief valve are arranged in series in the adjustment passage in this order from the rod side chamber side, The compression-side damping passage connects the piston-side chamber to the adjustment passage between the relief valve and the variable relief valve. A cylinder device characterized by:

3. The opening pressure of the extension-side relief valve is higher than the maximum opening pressure that the variable relief valve can attain in the actuator mode.

2. The cylinder device according to claim 1.

Images