Cylinder device

Abstract

To provide a cylinder device which can function as an actuator even if the cylinder device is a single rod type cylinder.SOLUTION: A cylinder device 1 of the invention comprises: a cylinder 2; a rod 3; a piston 4 that demarcates the inside of the cylinder 2 into a rod-side room R1 and a piston-side room R2; a reservoir room R that stores a liquid; an attenuation passage 5 that allows the rod-side room R1 and the piston-side room R2 to communicate with each other, and applies resistance to a flow of the liquid passing therethrough; a pressure-side attenuation passage 6 that applies resistance to a flow of the liquid from the piston-side room R2 to the reservoir room R; an extension-side suction passage 7 that allows only a flow of the liquid from the reservoir room R to the rod-side room R1; a pressure-side suction passage 8 that allows only a flow of the liquid from the reservoir room R to the piston-side room R2; a pump flow passage 9 allowing the rod-side room R1 and the piston-side room R2 to communicate with each other; a pump 10 midway on the pump flow passage 9; and a motor 11 that drives the pump 10.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] A conventional cylinder device is applied, for example, to an active suspension interposed between the body and axle of a vehicle, and specifically comprises a cylinder, a piston that is movably inserted into the cylinder and divides the interior of the cylinder into an upper chamber and a lower chamber, a rod connected to the piston, a damping passage that connects the upper chamber and the lower chamber and provides resistance to the flow of liquid passing through it, a pump passage that is parallel to the damping passage and connects the upper chamber and the lower chamber, a two-way discharge pump provided midway through the pump passage, and a motor that drives the pump (see, for example, Patent Document 1).

[0003] When a conventional cylinder device is used as an active suspension, the cylinder is connected to one of the vehicle body and the axle, and the rod is connected to the other of the vehicle body and the axle.The pump is driven by a motor to function as an actuator, generating thrust that can suppress vibrations of the vehicle body, and when it expands and contracts due to vibrations of the vehicle body, it can also function as a damper that generates a damping force to suppress vibrations of the vehicle body. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-196597 Summary of the Invention [Problem to be solved by the invention]

[0005] Conventional cylinder devices are so-called double-rod type cylinder devices in which the rod is inserted into the cylinder over the entire axial length of the cylinder and both ends of the rod protrude to the outside from both ends of the cylinder. Therefore, a double-rod type damper can function as an actuator simply by providing a pump flow path that connects the upper and lower chambers and a pump installed in the pump flow path.

[0006] However, when using a single-rod cylinder device, simply adding a pump flow path and a pump to a single-rod damper will not allow it to function as an actuator. This is because the amount of liquid in the upper chamber, through which the rod is inserted, and the lower chamber, through which the rod is not inserted, are not equal when the cylinder device extends or contracts. Therefore, when liquid is sent from the upper chamber to the lower chamber to drive the pump to extend the cylinder device, the amount of liquid that needs to be supplied to the lower chamber cannot be secured in the upper chamber, and negative pressure occurs in the upper chamber.

[0007] Therefore, an object of the present invention is to provide a cylinder device that can function as an actuator even if it is a single rod type. [Means for solving the problem]

[0008] In order to achieve the above object, the cylinder device in the problem-solving means of the present invention is configured to include a cylinder, a rod that is inserted into the cylinder so as to be movably axially, a piston that is connected to the rod and is inserted into the cylinder so as to be movably free, dividing the inside of the cylinder into a rod-side chamber and a piston-side chamber, a reservoir chamber that stores liquid, a damping passage that communicates between the rod-side chamber and the piston-side chamber and provides resistance to the flow of liquid passing through, a compression-side damping passage that provides resistance to the flow of liquid from the piston-side chamber to the reservoir chamber, an extension-side suction passage that allows only the flow of liquid from the reservoir chamber to the rod-side chamber, a compression-side suction passage that allows only the flow of liquid from the reservoir chamber to the piston-side chamber, a pump flow path that communicates between the rod-side chamber and the piston-side chamber, a bidirectional discharge pump provided in the pump flow path, and a motor that drives the pump.

[0009] According to the cylinder device configured in this manner, even if the pump is driven to supply liquid from the rod-side chamber to the piston-side chamber, the extension-side suction passage makes it possible to supply liquid from the reservoir chamber to the rod-side chamber, and the pressure in the rod-side chamber does not become negative. [Effects of the Invention]

[0010] As described above, according to the cylinder device of the present invention, even if it is a single rod type, it can function as an actuator. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a circuit diagram of a cylinder device according to one embodiment. [Figure 2] FIG. 2 is a diagram showing the characteristics of thrust and extension / contraction speed of the cylinder device in one embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] The present invention will be described below based on the embodiments shown in the drawings. As shown in FIG. 1, a cylinder device 1 in one embodiment includes a cylinder 2, a rod 3 inserted into the cylinder 2 so as to be movably axially, a piston 4 connected to the rod 3 and inserted into the cylinder 2 so as to be movably disposed therein, dividing the interior of the cylinder 2 into a rod-side chamber R1 and a piston-side chamber R2, a reservoir chamber R that stores liquid, a damping passage 5 that connects the rod-side chamber R1 and the piston-side chamber R2 and provides resistance to the flow of liquid passing therethrough, a compression-side damping passage 6 that provides resistance to the flow of liquid from the piston-side chamber R2 to the reservoir chamber R, an extension-side suction passage 7 that only allows liquid to flow from the reservoir chamber R to the rod-side chamber R1, a compression-side suction passage 8 that only allows liquid to flow from the reservoir chamber R to the piston-side chamber R2, a pump flow path 9 that connects the rod-side chamber R1 and the piston-side chamber R2, a bidirectional discharge pump 10 provided in the pump flow path 9, and a motor 11 that drives the pump 10.

[0013] When applying the cylinder device 1 to a vehicle, the cylinder 2 is connected to the unsprung member of the vehicle, and the rod 3 is connected to the sprung member, and the cylinder device 1 is interposed between the sprung member and the unsprung member. When applied to a vehicle, the cylinder device 1 suppresses vibrations of the vehicle body, which is the sprung member, and the vehicle wheels, which are the unsprung members, by exerting thrust.

[0014] Below, we will explain in detail each part of the cylinder device 1. The cylinder 2 is cylindrical, and has an annular rod guide 19 attached to its upper end in Fig. 1, and its lower end in Fig. 1 is closed by a lid 20. The rod 3 is inserted into the cylinder 2 via the inner periphery of the rod guide 19 so as to be movable in the axial direction, and its upper end in Fig. 1 protrudes outward from the cylinder 2.

[0015] The cylinder device 1 also includes an outer cylinder 21 that covers the outer periphery of the cylinder 2. The upper and lower ends of the outer cylinder 21 in FIG. 1 are closed by a rod guide 19 and a lid 20, similar to the cylinder 2, and a reservoir chamber R is formed in the annular gap between the cylinder 2 and the outer cylinder 21.

[0016] The tip of the rod 3, which is the lower end in FIG. 1, is connected to a piston 4 inserted into the cylinder 2, and the base end of the rod 3, which is the upper end in FIG. 1, protrudes outside the cylinder 2 through the inner periphery of a rod guide 19. In addition, although not shown, brackets are provided on the upper end of the rod 3 in FIG. 1 and on a cover 20 that closes the lower end of the cylinder 2 so that the cylinder device 1 can be attached to an installation location between the car body and the bogie.

[0017] As described above, the cylinder 2 is divided by the piston 4 into a rod-side chamber R1 (upper chamber in FIG. 1 ), through which the rod 3 is inserted over its entire length, and a piston-side chamber R2 (lower chamber in FIG. 1 ), through which the rod 3 is not inserted over its entire length. The rod-side chamber R1 and the piston-side chamber R2 are filled with a liquid such as hydraulic oil. The reservoir chamber R is filled with a liquid and a gas. The liquid in the rod-side chamber R1, the piston-side chamber R2, and the reservoir chamber R may be other liquids such as water or an aqueous solution, in addition to hydraulic oil. The gas in the reservoir chamber R is preferably an inert gas such as nitrogen, but may also be air. As described above, the cylinder device 1 is a single-rod hydraulic cylinder. When the rod 3 moves vertically in FIG. 1 together with the piston 4 relative to the cylinder 2, the volume displaced by the rod 3 within the cylinder 2 changes.

[0018] In the cylinder device 1 of the present embodiment, the damping passage 5 is provided in the piston 4. The damping passage 5 includes a passage 5a that communicates the rod-side chamber R1 and the piston-side chamber R2, and a damping valve 5b provided in the passage 5a. The damping valve 5b resists the flow of liquid passing through it while allowing the flow of liquid from the rod-side chamber R1 to the piston-side chamber R2 and from the piston-side chamber R2 to the rod-side chamber R1. Therefore, the damping passage 5 is configured as a passage that permits both the flow of liquid from the rod-side chamber R1 to the piston-side chamber R2 and the flow of liquid from the piston-side chamber R2 to the rod-side chamber R1. Note that the damping passage 5 may be configured to include a passage that is provided with a damping valve that permits only the flow of liquid from the rod-side chamber R1 to the piston-side chamber R2 and provides resistance to the flow of liquid, and a passage that is provided with a damping valve that permits only the flow of liquid from the piston-side chamber R2 to the rod-side chamber R1 and provides resistance to the flow of liquid. The damping valve 5b may be a variable throttle valve that can change the resistance to the flow of the liquid. Furthermore, the damping passage 5 may be provided somewhere other than the piston 4.

[0019] The compression side damping passage 6 is provided in the lid 20 and includes a passage 6a that connects the piston side chamber R2 and the reservoir chamber R, and a damping valve 6b that allows only the flow of liquid from the piston side chamber R2 to the reservoir chamber R and provides resistance to the flow of liquid, and is set as a one-way passage that allows only the flow of liquid from the piston side chamber R2 to the reservoir chamber R.

[0020] The extension-side suction passage 7 includes a passage 7a that connects the reservoir chamber R and the rod-side chamber R1, and a check valve 7b that allows liquid to flow only from the reservoir chamber R to the rod-side chamber R1, and is set as a one-way passage that allows liquid to flow only from the reservoir chamber R to the rod-side chamber R1.

[0021] The pressure side suction passage 8 is provided in the lid 20 and is equipped with a passage 8a that connects the reservoir chamber R and the piston side chamber R2, and a check valve 8b that only allows liquid to flow from the reservoir chamber R to the piston side chamber R2, and is set as a one-way passage that only allows liquid to flow from the reservoir chamber R to the piston side chamber R2.

[0022] The pump flow path 9 is parallel to the damping passage 5 and connects the rod-side chamber R1 and the piston-side chamber R2, with the pump 10 provided therein. The pump 10 is a bidirectional discharge pump, such as a vane pump, gear pump, or axial pump, as long as it has a rotating shaft (not shown) that can suck in and discharge fluid by rotating the rotating shaft and can also forcibly drive the rotating shaft by the flow of fluid. The rotating shaft of the pump 10 is connected to a motor 11. The motor 11 can be driven by electricity, and when forcibly rotated by input from the pump 10, it generates electricity and generates torque to suppress the rotation of the pump 10. The motor 11 may be any type of motor, whether DC or AC, such as a brushless motor, induction motor, or synchronous motor. A variable throttle valve may be provided in series with the pump 10 in the pump flow path 9.

[0023] The cylinder device 1 is configured as described above, and operation of the cylinder device 1 will be described below. First, operation of the cylinder device 1 when the pump 10 is stopped will be described. When the cylinder device 1 extends, the piston 4 moves upward in FIG. 1 relative to the cylinder 2, contracting the rod side chamber R1 and expanding the piston side chamber R2. The liquid in the contracting rod side chamber R1 passes through the damping passage 5 and the pump flow path 9 and moves to the expanding piston side chamber R2. Also, when the cylinder device 1 extends, the rod 3 moves out of the cylinder 2, causing a shortage of liquid in the cylinder 2, but the shortage of liquid is supplied from the reservoir chamber R to the piston side chamber R2 via the compression side suction passage 8. Then, the damping valve 5b in the damping passage 5 provides resistance to the flow of liquid, and the pump 10 is rotated by the liquid flowing through the pump flow path 9, which also provides resistance to the flow of liquid passing through the pump 10, causing the pressure in the rod side chamber R1 to rise. On the other hand, the check valve 8b in the compression-side suction passage 8 opens and the piston-side chamber R2 is connected to the reservoir chamber R, so the pressure in the piston-side chamber R2 becomes the tank pressure. The tank pressure is the pressure in the reservoir chamber R, and is the pressure of the gas sealed in the reservoir chamber R. In this way, when the cylinder device 1 is extended, the pressure in the rod-side chamber R1 becomes higher than the pressure in the piston-side chamber R2, and the cylinder device 1 generates an extension-side damping force that prevents the piston 4 from moving upward relative to the cylinder 2.

[0024] When the cylinder device 1 contracts, the piston 4 moves downward in FIG. 1 relative to the cylinder 2, contracting the piston-side chamber R2 and expanding the rod-side chamber R1. The liquid in the contracting piston-side chamber R2 passes through the damping passage 5 and the pump flow path 9 and moves to the expanding rod-side chamber R1. Also, when the cylinder device 1 contracts, the rod 3 enters the cylinder 2, causing an excess of liquid in the cylinder 2. The excess liquid is discharged from the piston-side chamber R2 to the reservoir chamber R via the compression-side damping passage 6. The damping valve 5b in the damping passage 5 provides resistance to the flow of liquid, and the pump 10 is rotated by the liquid flowing through the pump flow path 9, which also provides resistance to the flow of liquid passing through the pump 10. Therefore, the pressure in the piston-side chamber R2 becomes higher than the pressure in the rod-side chamber R1. Also, the pressure in the piston-side chamber R2 becomes higher than the pressure in the reservoir chamber R because the compression-side damping passage 6 provides resistance to the flow of liquid. In this way, when the cylinder device 1 is contracted, the pressure in the piston side chamber R2 becomes higher than the pressure in the rod side chamber R1, and the cylinder device 1 generates a compression side damping force that prevents the piston 4 from moving downward relative to the cylinder 2. In this way, when the cylinder device 1 is forcibly extended or retracted by an external force while the pump 10 is stopped, the characteristics of the thrust and extension / retraction speed of the cylinder device 1 become passive characteristics, as shown by the dashed line in Figure 2, in which the thrust generated by the cylinder device 1 increases according to the extension / retraction speed of the cylinder device 1, and the cylinder device 1 functions as a damper by exerting a damping force that prevents extension or retraction.

[0025] Next, we will explain the operation of the cylinder device 1 when the pump 10 is driven to cause the cylinder device 1 to function as an actuator. When the pump 10 sucks liquid from the piston-side chamber R2 and supplies it to the rod-side chamber R1, the liquid supplied into the rod-side chamber R1 generates a force that presses the piston 4 downward in FIG. 1 relative to the cylinder 2. Here, when the cylinder device 1 extends, the rod 3 retracts from the cylinder 2, and liquid is supplied from the reservoir chamber R via the compression-side suction passage 8 into the expanding piston-side chamber R2. Therefore, when the cylinder device 1 extends while the pump 10 is driven to supply liquid to the rod-side chamber R1, as shown in the first quadrant in FIG. 2, the thrust generated by driving the pump 10 can be superimposed in the direction of pressing down the piston 4 on the thrust of the passive characteristics, and the thrust of the cylinder device 1 can be adjusted in magnitude in the region X1 between the passive characteristics and the characteristic line when a maximum current is supplied to the motor 11, shown by the solid line A in FIG. 2, depending on the amount of current supplied to the motor 11. In the first quadrant, the cylinder device 1 generates a thrust that hinders extension while applying a force that pushes down the piston 4 due to the drive of the pump 10. Note that by driving the pump 10, some of the liquid supplied into the rod side chamber R1 moves to the piston side chamber R2 via the damping passage 5, but since the flow rate of liquid passing through the damping passage 5 is greater than when the pump 10 is stopped, the pressure difference between the rod side chamber R1 and the piston side chamber R2 is greater than when the pump 10 is stopped, so the cylinder device 1 can generate a greater thrust compared to the passive characteristics.

[0026] When the pump 10 is driven to suck liquid from the piston side chamber R2 and supply it to the rod side chamber R1, and the cylinder device 1 contracts, the rod 3 enters the cylinder 2, and liquid is discharged into the contracting piston side chamber R2 via the compression side damping passage 6 into the reservoir chamber R. Therefore, when the cylinder device 1 contracts while driving the pump 10 to supply liquid to the rod side chamber R1, as shown in the second and third quadrants in FIG. 2, the thrust generated by driving the pump 10 can be superimposed in the direction of pushing down the piston 4 on the thrust of the passive characteristics, and the thrust of the cylinder device 1 can be adjusted in magnitude in an area X2 between the passive characteristics and the characteristic line when a maximum current is applied to the motor 11, as shown by the solid line A in FIG. 2, depending on the amount of current applied to the motor 11. When the pump 10 is driven, part of the liquid supplied into the rod side chamber R1 moves to the piston side chamber R2 through the damping passage 5. Even when the cylinder device 1 is contracting, the pressure in the rod side chamber R1 can be made greater than the pressure in the cylinder device 1, and the cylinder device 1 can exert a thrust that promotes contraction.

[0027] In addition, when the maximum current is applied to the motor 11 indicated by the solid line A in the second and third quadrants, the thrust of the cylinder device 1 becomes passive when the contraction speed of the cylinder device 1 exceeds a certain contraction speed. This is because the volume expansion of the rod side chamber R1, which expands due to the contraction of the cylinder device 1, exceeds the maximum flow rate that can be supplied into the rod side chamber R1, which is expanded by the pump 10, and liquid moves through the damping passage 5 from the piston side chamber R2 to the rod side chamber R1, causing the pressure in the piston side chamber R2 to exceed the pressure in the rod side chamber R1, and the cylinder device 1 can no longer generate thrust that promotes contraction. In this way, in the second quadrant, the cylinder device 1 is in a state where it contracts by driving the pump 10 and generates thrust that actively promotes contraction. In addition, in the third quadrant, the cylinder device 1 is in a state where it contracts and generates thrust that hinders contraction, and the force of the pump 10 pushing down the piston 4 reduces the thrust generated by the cylinder device 1 below the passive characteristic.

[0028] Next, when the pump 10 sucks liquid from the rod-side chamber R1 and supplies the liquid to the piston-side chamber R2, the liquid supplied into the piston-side chamber R2 generates a force that presses the piston 4 upward in FIG. 1 relative to the cylinder 2. Here, when the cylinder device 1 contracts, the piston 4 moves downward in FIG. 1, expanding the rod-side chamber R1, and the liquid in the rod-side chamber R1 is supplied to the piston-side chamber R2 by driving the pump 10. Therefore, the check valve 7b in the extension-side suction passage 7 opens, connecting the reservoir chamber R and the rod-side chamber R1, and the liquid equivalent to the expansion of the rod-side chamber R1 and the liquid supplied to the piston-side chamber R2 by the pump 10 is replenished from the reservoir chamber R, preventing the rod-side chamber R1 from becoming negative pressure, and the cylinder device 1 can function as an actuator by driving the pump 10.

[0029] When the cylinder device 1 contracts while driving the pump 10 to supply liquid to the piston side chamber R2, the thrust generated by driving the pump 10 can be superimposed in the direction of pushing up the piston 4 on the thrust of the passive characteristic, as shown in the third quadrant in Fig. 2, and the thrust of the cylinder device 1 can be adjusted in magnitude in an area Y1 between the passive characteristic and the characteristic line when the maximum current is applied to the motor 11, shown by the solid line B in Fig. 2, depending on the amount of current applied to the motor 11. In the third quadrant, the cylinder device 1 contracts by adding a force to push up the piston 4 by driving the pump 10, while generating a thrust that hinders contraction.

[0030] When the pump 10 is driven to suck liquid from the rod-side chamber R1 and supply it to the piston-side chamber R2, and the cylinder device 1 extends, the piston 4 moves upward in FIG. 1 , expanding the piston-side chamber R2, and the liquid in the rod-side chamber R1 is supplied to the piston-side chamber R2 by driving the pump 10. Because the cylinder device 1 is a single-rod type cylinder device, when the cylinder device 1 extends, the rod 3 moves out of the cylinder 2, and the volume increase in the piston-side chamber R2 is greater than the volume decrease in the rod-side chamber R1. Therefore, if the pump 10 were to supply liquid only from the rod-side chamber R1 to the piston-side chamber R2, the amount of liquid in the cylinder 2 would be insufficient. However, since the cylinder device 1 of this embodiment is provided with the extension-side suction passage 7, the shortage of liquid is supplied from the reservoir chamber R via the extension-side suction passage 7. Therefore, the liquid that is insufficient in the cylinder 2 is replenished from the reservoir chamber R, preventing the rod-side chamber R1 from becoming negative pressure, and the cylinder device 1 can function as an actuator by driving the pump 10.

[0031] When the cylinder device 1 extends while driving the pump 10 to supply liquid to the piston side chamber R2, the thrust generated by driving the pump 10 can be superimposed on the passive characteristics in the direction of pushing up the piston 4, as shown in the fourth and first quadrants in FIG. 2, and the thrust of the cylinder device 1 can be adjusted in magnitude in area Y2 between the passive characteristics and the characteristic line when the maximum current is supplied to the motor 11, as shown by the solid line B in FIG. 2, depending on the amount of current supplied to the motor 11. In addition, when the maximum current is applied to the motor 11 indicated by the solid line B in the fourth and first quadrants, the thrust of the cylinder device 1 becomes passive when the extension / contraction speed of the cylinder device 1 exceeds a certain extension / contraction speed. This is because the volume expansion of the piston side chamber R2, which expands due to the extension of the cylinder device 1, exceeds the maximum flow rate that the pump 10 can supply to the expanding piston side chamber R2, and liquid moves from the rod side chamber R1 to the piston side chamber R2 through the damping passage 5, causing the pressure in the rod side chamber R1 to exceed the pressure in the piston side chamber R2, and the cylinder device 1 can no longer generate thrust that promotes extension. In this way, in the fourth quadrant, the cylinder device 1 is in a state where it is extending by the drive of the pump 10 while generating thrust that actively promotes extension. In addition, in the first quadrant, the cylinder device 1 is in a state where it is extending while generating thrust that hinders extension, and the force pushing up the piston 4 by the drive of the pump 10 operates to reduce the thrust generated by the cylinder device 1 below the passive characteristic.

[0032] The cylinder device 1 configured in this manner can function as both a damper and an actuator, and when extended or retracted by an external force, the torque of the motor 11 suppresses the rotation of the pump 10, that is, the motor 11 is used in the braking region to generate torque in the opposite direction to the rotation direction of the pump 10. Therefore, the cylinder device 1 can perform power regeneration by using the motor 11 in the braking region to cause the motor 11 to generate power and convert kinetic energy into electrical energy. Furthermore, if the damping valve 5b provided in the damping passage 5 of the cylinder device 1 is a variable throttle valve and a variable throttle valve is provided in series with the pump 10 in the pump flow path 9, the torque and rotation speed of the motor 11 operating in the braking region can be controlled by adjusting the opening of the two variable throttle valves, thereby improving the efficiency of power regeneration of the motor 11.

[0033] As described above, the cylinder device 1 of this embodiment is configured to include the cylinder 2, the rod 3 inserted into the cylinder 2 so as to be movably axially, the piston 4 connected to the rod 3 and inserted into the cylinder 2 so as to be movably disposed therein, dividing the interior of the cylinder 2 into a rod-side chamber R1 and a piston-side chamber R2, a reservoir chamber R that stores liquid, a damping passage 5 that communicates between the rod-side chamber R1 and the piston-side chamber R2 and provides resistance to the flow of liquid passing therethrough, a compression-side damping passage 6 that provides resistance to the flow of liquid from the piston-side chamber R2 to the reservoir chamber R, an extension-side suction passage 7 that allows only the flow of liquid from the reservoir chamber R to the rod-side chamber R1, a compression-side suction passage 8 that allows only the flow of liquid from the reservoir chamber R to the piston-side chamber R2, a pump flow path 9 that communicates between the rod-side chamber R1 and the piston-side chamber R2, a bidirectional discharge pump 10 that is provided in series in the pump flow path 9, and a motor 11 that drives the pump 10.

[0034] According to the cylinder device 1 configured in this manner, even when the pump 10 is driven to supply liquid from the rod-side chamber R1 to the piston-side chamber R2, the pressure in the rod-side chamber R1 does not become negative because the extension-side suction passage 7 is provided, and liquid can be supplied from the reservoir chamber R to the rod-side chamber R1. Therefore, according to the cylinder device 1 of the present embodiment, even though it is configured as a single-rod type cylinder device, it can function not only as a damper but also as an actuator.

[0035] In the cylinder device 1 of the present embodiment, the gas pressure in the reservoir chamber R may be increased, and the reservoir chamber R may be used as an accumulator that increases the pressure in the cylinder 2. Furthermore, in the cylinder device 1 of the present embodiment, the outer cylinder 21 is provided on the outer periphery of the cylinder 2, and the reservoir chamber R is provided between the cylinder 2 and the outer cylinder 21. However, the reservoir chamber R may be formed by a reservoir tank that is provided separately and independently from the cylinder 2 without providing the outer cylinder 21. In that case, the reservoir chamber R and the rod side chamber R1 in the reservoir tank may be connected by a pipe that functions as the passage 7a of the extension-side suction passage 7, and the reservoir chamber R and the piston-side chamber R2 may be connected by a pipe that functions as the passage 6a of the compression-side damping passage 6 and a pipe that functions as the passage 8a of the compression-side suction passage 8. When a reservoir chamber R is provided in the reservoir tank in this manner, when the cylinder device 1 is applied to a vehicle, the cylinder 2 can be connected to one of the sprung member and the unsprung member, and the rod 3 can be connected to the other of the sprung member and the unsprung member.

[0036] Although the preferred embodiment of the present invention has been described in detail, modifications, variations and changes can be made thereto without departing from the scope of the appended claims. [Explanation of symbols]

[0037] 1 Cylinder device, 2 Cylinder, 3 Rod, 4 Piston, 5 Damping passage, 6 Compression side damping passage, 7 Extension side suction passage, 8 Compression side suction passage, 9 Pump flow passage, 10 Pump, 11 Motor, R Reservoir chamber, R1 Rod side chamber, R2 Piston side chamber

Claims

[Claim 1] A cylinder; a rod inserted into the cylinder so as to be axially movable; a piston connected to the rod and movably inserted into the cylinder, dividing the interior of the cylinder into a rod-side chamber and a piston-side chamber; a reservoir chamber for storing a liquid; a damping passage that communicates the rod-side chamber with the piston-side chamber and provides resistance to the flow of liquid passing through the damping passage; a compression-side damping passage that provides resistance to the flow of fluid from the piston-side chamber toward the reservoir chamber; an extension-side suction passage that allows only a flow of liquid from the reservoir chamber toward the rod-side chamber; a pressure-side suction passage that allows only a flow of liquid from the reservoir chamber toward the piston-side chamber; a pump flow path that communicates the rod-side chamber and the piston-side chamber; a two-way discharge pump provided in the pump flow path; a motor for driving the pump; A cylinder device characterized by:

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