JP6630186B2 - Shock absorber - Google Patents

Description

  The present invention relates to a shock absorber that is mounted on, for example, a railway vehicle and is preferably used to dampen vibration of the vehicle.

  Generally, a hydraulic shock absorber as a cylinder device is provided between each bogie of a railway vehicle and a vehicle body so as to buffer vibration of the railway vehicle (for example, see Patent Document 1). This type of conventional hydraulic shock absorber includes a cylinder filled with a working fluid, a piston inserted into the cylinder to partition the inside of the cylinder into a rod-side oil chamber and a non-rod-side oil chamber, A piston rod connected to the piston and extending to the outside of the cylinder, a flow path in which a flow of a working fluid is generated by sliding of the piston in the cylinder, and a flow path provided in the flow path as the piston moves. A valve mechanism for adjusting the flow rate of the working fluid passing through the flow path.

JP 2009-287609 A

  By the way, in the conventional hydraulic shock absorber, when the piston in the cylinder is slid and displaced, the valve element of the valve mechanism provided in the flow passage opens and closes the flow passage to generate a damping force. In this case, since the valve element slides in the flow path, there is a problem in that the valve element wears due to the sliding, the flow path area changes, and the damping force decreases.

  SUMMARY OF THE INVENTION The present invention has been made in consideration of the above-described problems of the related art, and an object of the present invention is to provide a shock absorber capable of suppressing a decrease in damping force due to wear of a valve body.

In order to solve the above-described problem, the present invention provides a cylinder in which a working fluid is sealed, and a piston inserted into the cylinder to partition the inside of the cylinder into a rod-side oil chamber and a non-rod-side oil chamber. A piston rod connected to the piston and extending to the outside of the cylinder, a flow path in which a flow of a working fluid is generated by sliding of the piston in the cylinder, and a movement of the piston provided in the flow path. a valve mechanism for regulating the flow rate of the working fluid passing through the flow path, the shock absorber comprising wherein the valve mechanism is provided et the valve element housing chamber between the inlet passage and the outlet passage of the working fluid A valve body movably housed in the valve body housing chamber to open and close the inflow passage, and a spring means for urging the valve body in a direction in which the inflow passage closes. , The flow at one end Sliding a sliding shaft which slides in the passage, the opening and closing section for opening and closing the inflow passage is formed integrally with one axial end of the sliding shaft of the valve body, the inlet passage A movable sliding portion is provided, and between the other end of the sliding shaft portion in the axial direction and the inflow passage, when the valve body is closed, the valve body is shut off from the valve housing chamber and the valve is opened. Sometimes, a non-sliding portion of an annular groove communicating with the valve body accommodating chamber and making the sliding shaft portion and the inflow passage non- sliding over the entire circumference is formed, and the sliding shaft portion is formed. A shaft passage connecting the inflow passage and the valve body housing chamber through the non-sliding portion is formed on the outer peripheral side of the shaft so as to extend in the axial direction.

  ADVANTAGE OF THE INVENTION According to this invention, the fall of the damping force by wear of a valve body can be suppressed.

It is sectional drawing which shows the shock absorber by embodiment of this invention. FIG. 2 is an enlarged view of a portion II in FIG. 1. It is a perspective view which shows the valve body in FIG. 2 by itself. It is sectional drawing which shows a valve mechanism when a valve element opens. FIG. 5 is a cross-sectional view of the valve mechanism as viewed from a VV direction in FIG. 4. It is sectional drawing similar to FIG. 4 which shows the valve mechanism after a valve body wears. It is sectional drawing which shows the valve body by a modification.

  Hereinafter, the shock absorber according to the embodiment of the present invention will be described in detail with reference to the accompanying drawings, taking as an example a case where the shock absorber is applied to a hydraulic shock absorber of a railway vehicle or the like.

  First, a hydraulic shock absorber 1 according to an embodiment of the present invention will be described with reference to FIGS. The hydraulic shock absorber 1 is configured to include a cylindrical outer cylinder 2, an inner cylinder 6, a piston 8, a piston rod 9, a rod guide 10, a flow path 11, and a valve mechanism 13 which form an outer shell. The hydraulic shock absorber 1 is mounted, for example, horizontally between a vehicle body of a railway vehicle and a bogie (both not shown).

  The outer cylinder 2 of the hydraulic shock absorber 1 is provided on the outer peripheral side of the inner cylinder 6 and is provided coaxially with the inner cylinder 6. One end (left end in FIG. 1) of the outer cylinder 2 is closed by a bottom cap 3, and the other end (right end in FIG. 1) is closed by a rod guide 10 described later. At the other end of the outer cylinder 2, a cylindrical cover 4 that covers a piston rod 9 described later is attached. Here, the bottom cap 3 and the cylindrical cover 4 are provided with mounting eyes 5A and 5B that are mounted on, for example, a vehicle body and a bogie of a railway vehicle.

  The inner cylinder 6 of the hydraulic shock absorber 1 forms a cylinder and is provided coaxially within the outer cylinder 2. One end of the inner cylinder 6 is fitted and fixed to the bottom cap 3 via a bottom valve 7. The other end of the inner cylinder 6 is fitted with a rod guide 10. A working fluid as a working fluid is sealed in the inner cylinder 6. The working fluid is not limited to working oil and oil, but may be, for example, water mixed with additives.

  In this case, an annular reservoir chamber A is formed between the inner cylinder 6 and the outer cylinder 2, and gas is sealed in the reservoir chamber A together with the working fluid. This gas may be air at atmospheric pressure, or a gas such as compressed nitrogen gas may be used. The gas in the reservoir chamber A is compressed when the piston rod 9 is contracted (contraction stroke) to compensate for the volume of the piston rod 9 entering.

  As shown in FIG. 1, the bottom valve 7 is provided between the bottom cap 3 and the inner cylinder 6 at one end of the inner cylinder 6. The bottom valve 7 is provided with a suction valve 7A as a bottom-side valve that allows the working fluid in the reservoir chamber A to flow toward the bottom-side oil chamber C in the inner cylinder 6 and prevents a reverse flow. Have been.

  Here, the suction valve 7A is opened such that when the piston 8 slides and displaces in the axial direction (rod extension side) in the inner cylinder 6, the inside of the inner cylinder 6 is always kept filled with the hydraulic fluid. , Close the valve. That is, when the piston 8 slides and displaces in the inner cylinder 6 in the direction of the rod-side oil chamber B during the extension stroke of the piston rod 9, the suction valve 7A is opened and the hydraulic fluid in the reservoir chamber A is changed to the bottom-side oil. Inflow or suction into chamber C.

  The piston 8 is a movable partition slidably inserted (inserted) into the inner cylinder 6. This piston 8 divides the inside of the inner cylinder 6 into two pressure chambers: a bottom oil chamber C as one oil chamber and a rod oil chamber B as another oil chamber (anti-rod oil chamber). (Define). The piston 8 is provided with a check valve 8A as a piston valve that allows the hydraulic fluid to flow from the bottom-side oil chamber C to the rod-side oil chamber B and prevents a reverse flow.

  Here, the check valve 8A is designed to keep the inside of the inner cylinder 6 constantly filled with the hydraulic fluid when the piston 8 slides and displaces in the axial direction (rod reduction side) in the inner cylinder 6. Open and close the valve. That is, when the piston 8 slides and displaces in the inner cylinder 6 in the direction of the bottom oil chamber C during the reduction stroke of the piston rod 9, the check valve 8A opens and the hydraulic fluid in the bottom oil chamber C is discharged. It is sucked into the rod side oil chamber B.

  One end of the piston rod 9 is connected to the piston 8 in the inner cylinder 6. On the other hand, the other end side (projecting end side) of the piston rod 9 protrudes extensibly so as to extend to the outside of the inner cylinder 6 via the rod guide 10 and the like. The other end of the piston rod 9 is attached to, for example, a bogie of a railway vehicle via an attachment eye 5B.

  The rod guide 10 is located on the other end side of the outer cylinder 2 and the inner cylinder 6, and is formed in a stepped cylindrical shape. The rod guide 10 positions the other side of the inner cylinder 6 at the center of the outer cylinder 2 and guides (guides) the piston rod 9 slidably in the axial direction on the inner peripheral side. Here, the rod guide 10 is provided in the flow path 11 in which the flow of the hydraulic fluid is generated by the sliding of the piston 8 in the inner cylinder 6, the valve body storage chamber 12 in which the valve mechanism 13 is stored, and the flow path 11. A valve mechanism 13 for adjusting the flow rate of the hydraulic fluid is provided.

  The flow path 11 is located in the rod guide 10 and is provided between the reservoir chamber A and the rod-side oil chamber B. The flow path 11 includes an inflow passage 11A formed by piercing the rod guide 10 in an L shape, an outflow passage 11B formed by piercing the rod guide 10 in the axial direction, and an outflow passage. Outflow pipe 11C connected to 11B. The flow path 11 generates a flow of hydraulic fluid by sliding the piston 8, and circulates hydraulic fluid in the rod-side oil chamber B toward the reservoir chamber A.

  Here, the outflow pipe 11C is formed of, for example, a flexible pipe. The base end of the outflow pipe 11C is connected to the outflow passage 11B, and the tip end of the outflow pipe 11C is submerged (immersed) in the working fluid in the reservoir chamber A. Thereby, the hydraulic fluid sucked from the rod-side oil chamber B can be supplied into the hydraulic fluid in the reservoir chamber A via the flow path 11.

  The valve body accommodation chamber 12 is provided in the rod guide 10 and provided between the inflow passage 11A and the outflow passage 11B, and constitutes a part of the flow passage 11. The valve body accommodating chamber 12 is formed as a stepped annular hole formed in the radial direction from the outer peripheral side to the inner peripheral side of the rod guide 10. The valve housing chamber 12 communicates the inflow passage 11A with the outflow passage 11B and accommodates the valve mechanism 13.

  Here, one side (the piston rod 9 side) of the valve body accommodating chamber 12 communicates with the inflow passage 11A, and is formed with a tapered seat surface 12A on which an opening / closing portion 14C of the valve body 14 described later is seated. A counterbore 12 </ b> B for embedding a screw 16, which will be described later, in the valve body accommodation chamber 12 is formed on the other side (the outer cylinder 2 side) of the valve body accommodation chamber 12. On the other hand, the downstream side (bottom cap 3 side) of the valve body housing chamber 12 communicates with the outflow passage 11B.

  The valve mechanism 13 is located in the valve body accommodation chamber 12 and provided in the flow path 11. The valve mechanism 13 includes a valve body 14 that opens and closes the inflow passage 11A with respect to the outflow passage 11B, a spring 15 that constantly urges the valve body 14 in the valve closing direction, and a screw 16 that supports the spring 15. Have been. The valve mechanism 13 generates a damping force by adjusting the flow rate of the hydraulic fluid passing through the inside of the flow path 11 as the piston 8 moves. That is, the valve mechanism 13 is configured as a pressure regulating valve that opens at a predetermined pressure and changes the opening area (opening degree) according to the moving speed of the piston 8.

  The valve element 14 is accommodated in the valve element accommodation chamber 12 and is provided movably in the valve element accommodation chamber 12. The valve body 14 includes a first shaft portion 14A having a small diameter formed at one axial end of the valve body 14, a second shaft portion 14B having a large diameter formed at the other axial end of the valve body 14, An annular opening / closing portion 14C disposed between the first shaft portion 14A and the second shaft portion 14B is integrally formed. As shown in FIG. 3, the valve element 14 is formed as a stepped cylindrical poppet valve. It opens and closes with respect to 11B.

  The first shaft portion 14A is formed on one axial side of the valve body 14 as a sliding shaft portion that slides in the inflow passage 11A. The first shaft portion 14A is formed as a columnar protruding member extending from the opening / closing portion 14C toward the piston rod 9 side. A sliding portion 14A1 that slides in the inflow passage 11A is provided at one axial end of the first shaft portion 14A, and an outer peripheral side of the first shaft portion 14A is provided at the other axial end of the first shaft portion 14A. An annular space 14A2 formed by notching is formed.

  Here, the space portion 14A2 is provided on the outer peripheral side of the first shaft portion 14A, adjacent to the opening / closing portion 14C of the valve body 14. The space portion 14A2 is located between the first shaft portion 14A and the opening / closing portion 14C and the inflow passage 11A, and keeps the first shaft portion 14A and the inner peripheral surface of the inflow passage 11A in a non-contact state. . The axial dimension (S + H) of the space portion 14A2 is set to be larger than a dimension S, which is a dimension between the second shaft portion 14B and the convex portion 16B described later. In this case, when the valve body 14 is closed, the space 14A2 is shut off from the valve body accommodating chamber 12 by the seating surface 14C1 of the opening / closing section 14C described later sitting on the seat surface 12A of the valve body accommodating chamber 12. (See FIG. 2). On the other hand, when the valve 14 is opened, the space 14A2 communicates with the valve housing chamber 12 by the seating surface 14C1 being separated from the seat surface 12A (see FIG. 4).

  Further, as shown in FIG. 3, the first shaft portion 14A is provided with a shaft portion passage 14A3 formed of a pair of slit grooves opened on the outer peripheral surface thereof, facing the radial direction. The shaft passage 14A3 is formed so as to extend in the axial direction by notching in an arc shape from the tip of the first shaft 14A to a substantially central position in the longitudinal direction of the first shaft 14A. The shaft passage 14A3 communicates the inflow passage 11A with the inside of the valve body accommodating chamber 12 via the space 14A2, and adjusts the flow passage area of the hydraulic fluid flowing through the inflow passage 11A. Here, it is preferable that the flow passage area of the working fluid flowing through the shaft portion passage 14A3 and the flow passage area of the working fluid flowing through the space portion 14A2 are formed to have substantially the same flow passage area. Thereby, both can be formed as substantially the same throttle passage (flow passage area).

  The second shaft portion 14B is formed on the other axial side of the valve body 14. The second shaft portion 14B has a larger radial dimension than the first shaft portion 14A, and is formed as a columnar projecting member extending from the opening / closing portion 14C toward the outer cylinder 2 side. The other end in the axial direction of the second shaft portion 14 </ b> B comes into contact with the convex portion 16 </ b> B of the screw 16 when the valve body 14 is opened, and regulates the movement of the valve body 14.

  The opening / closing portion 14C is formed between the first shaft portion 14A and the second shaft portion 14B. The opening / closing portion 14C is formed as a flange protruding radially outward over the entire circumference from the outer peripheral side of the second shaft portion 14B. One axial end surface of the opening / closing portion 14C forms a seating surface 14C1 that sits on the seat surface 12A of the valve body housing chamber 12 when the valve body 14 is closed. On the other hand, the other axial end surface of the opening / closing portion 14C forms a bearing surface 14C2 that supports one axial side of the spring 15.

  Further, the opening / closing portion 14C is provided with an opening / closing portion passage 14C3 formed of a pair of slit grooves opened on the outer peripheral surface thereof, facing the radial direction. The opening / closing portion passage 14C3 is formed so as to extend in the axial direction by notching an arc from the seating surface 14C1 to the bearing surface 14C2. Specifically, as shown in FIG. 5, the opening / closing portion passage 14C3 and the space portion 14A2 are provided at the same position in the circumferential direction of the valve body 14, and are formed into a shape through which the hydraulic fluid can easily flow. . The opening / closing passage 14C3 communicates the inflow passage 11A with the inside of the valve body accommodating chamber 12 via the space 14A2.

  Thus, the opening / closing section 14C opens and closes the inflow passage 11A in conjunction with the sliding displacement of the piston 8. That is, when the valve body 14 is closed, the seating surface 14C1 of the opening / closing portion 14C sits on the seat surface 12A, and shuts off the inflow passage 11A from the valve housing chamber 12. On the other hand, when the valve body 14 is opened, the seating surface 14C1 of the opening / closing portion 14C is separated from the seat surface 12A, and the inflow passage 11A communicates with the valve body housing chamber 12.

  The spring 15 is provided as a spring means between the opening / closing portion 14C of the valve body 14 and the screw 16 so as to surround the second shaft portion 14B of the valve body 14. The spring 15 is constituted by, for example, a coil spring and constantly urges the valve body 14 in a direction in which the inflow passage 11A is closed. That is, the spring 15 urges the valve element 14 in a direction away from the screw 16 toward the piston rod 9.

  The screw 16 is located on the other side in the axial direction of the valve body housing chamber 12 and is screwed to the inner peripheral surface of the valve body housing chamber 12. The screw 16 is formed in a stepped cylindrical shape as a whole, and includes a spring receiving portion 16A that supports the spring 15 and a convex portion 16B that projects from the spring receiving portion 16A toward the piston rod 9. The convex portion 16B regulates the movement of the valve body 14 when the other end of the second shaft portion 14B abuts when the valve body 14 is opened.

  The hydraulic shock absorber 1 as the cylinder device according to the present embodiment has the above-described configuration. Next, the operation thereof will be described.

  The mounting eye 5A of the bottom cap 3 located at one end of the hydraulic shock absorber 1 is mounted on, for example, the body of a railway vehicle. The mounting eye 5B at the other end of the piston rod 9 is mounted on, for example, a bogie of a railway vehicle. Thereby, the piston rod 9 can be axially extended from the inner cylinder 6 or contracted in the inner cylinder 6 in the axial direction, so that the vibration of the railway vehicle can be damped.

  That is, when the piston rod 9 is in the extension stroke, when the piston 8 slides and displaces in the axial direction (rod extension side), the pressure in the rod-side oil chamber B becomes high, so the pressure in the rod-side oil chamber B becomes high. When the pressure exceeds a predetermined valve opening pressure, the valve element 14 of the valve mechanism 13 opens, and the hydraulic fluid flows into the valve element accommodating chamber 12 from the inflow path 11A and flows out of the outflow path 11B and the outflow pipe 11C. It flows out toward the reservoir chamber A through. Thereby, the valve mechanism 13 can buffer the extension operation of the piston rod 9 so as to suppress the extension operation.

  In the extension stroke of the piston rod 9, an amount of hydraulic fluid corresponding to the advanced volume of the piston rod 9 advanced from the inner cylinder 6 is supplied from the reservoir chamber A to the bottom side oil via the suction valve 7A of the bottom valve 7. It flows into the room C. In this case, the check valve 8A provided on the piston 8 allows the hydraulic fluid in the bottom oil chamber C to flow to the rod oil chamber B and prevents the hydraulic oil from flowing in the opposite direction. The hydraulic fluid does not flow from B into the bottom oil chamber C.

  Here, when the pressure in the rod-side oil chamber B exceeds a predetermined valve opening pressure, the valve element 14 of the valve mechanism 13 opens, and the hydraulic fluid in the rod-side oil chamber B flows from the inflow passage 11A. The fluid flows into the valve body accommodating chamber 12 through the shaft passage 14A3 and the space 14A2 of the body 14. The hydraulic fluid that has flowed into the valve housing chamber 12 flows toward the outflow passage 11B and the outflow pipe 11C via the opening / closing passage 14C3, and flows out into the reservoir chamber A. In this case, since the stroke dimension of the valve element 14 is set to the dimension S which is the dimension between the second shaft portion 14B and the convex portion 16B, the sliding dimension at which the sliding occurs in the inflow passage 11A is also the dimension. S (see FIG. 2). On the other hand, the non-sliding dimension in which sliding does not occur in the inflow passage 11A is a dimension H obtained by subtracting the dimension S from the axial dimension (S + H) of the space 14A2.

  At this time, as shown in FIG. 4, the hydraulic fluid flowing through the shaft passage 14A3 and the space 14A2 gradually increases the damping force according to the moving speed of the piston 8 due to the orifice action. Such a damping force is generated. In addition, when the second shaft portion 14B of the valve body 14 comes into contact with the convex portion 16B of the screw 16, the flow area of the working fluid flowing in the valve body housing chamber 12 does not change any more. Damping force increases. Specifically, as shown in FIG. 5, the flow area of the hydraulic fluid flowing from the inflow passage 11A into the valve body accommodating chamber 12 is the combined area of the cross-sectional areas of the space 14A2 and the shaft passage 14A3. .

  On the other hand, when the piston rod 9 is in the reduction stroke, when the piston 8 is slid and displaced in the axial direction (rod reduction side), the pressure in the bottom oil chamber C becomes high. The liquid flows into the rod-side oil chamber B via a check valve 8A provided on the piston 8. In this case, the suction valve 7A provided in the bottom valve 7 allows the working fluid in the reservoir chamber A to flow to the bottom side oil chamber C in the inner cylinder 6 and blocks the flow in the opposite direction. The hydraulic fluid does not flow from the side oil chamber C into the reservoir chamber A.

  When the pressure in the rod-side oil chamber B exceeds a predetermined valve opening pressure, the valve element 14 of the valve mechanism 13 opens, and the hydraulic fluid in the rod-side oil chamber B flows from the inflow passage 11A through the valve element. It flows into the storage chamber 12 and flows out toward the reservoir chamber A via the outflow passage 11B and the outflow pipe 11C. Thus, similarly to the extension stroke of the piston rod 9, the valve mechanism 13 can buffer the piston rod 9 so as to suppress the contraction operation.

  Here, the hydraulic shock absorber 1 has a uniflow structure. That is, the hydraulic fluid in the inner cylinder 6 always flows in one direction from the rod-side oil chamber B to the reservoir chamber A via the flow path 11 in both the extension stroke and the contraction stroke of the piston rod 9. . Accordingly, if the moving distance of the piston 8 in the axial direction is the same, the same amount of hydraulic fluid passes through the valve mechanism 13 from the rod-side oil chamber B, so that the same damping force is generated.

  By the way, the hydraulic fluid in the inflow passage 11A slides on the valve element 14 of the valve mechanism 13 by the expansion and contraction of the piston rod 9, so that the inner peripheral surface of the inflow passage 11A and the outer peripheral surface of the sliding portion 14A1 of the valve element 14 are provided. Wears out. In this case, since the space 14A2 is kept in a non-contact state with the inner peripheral surface of the inflow passage 11A, no abrasion occurs. That is, as shown in FIG. 6, the outer peripheral side of the sliding portion 14A1 is worn and its radial dimension is reduced, but the radial dimension of the space 14A2 does not change. Even after the valve body 14 is worn, the flow area of the hydraulic fluid flowing into the valve body housing chamber 12 from the inflow passage 11A is, as shown in FIG. 5, the cross-sectional area of the space portion 14A2 and the shaft portion passage 14A3. Is the combined area. Thus, the flow area of the hydraulic fluid flowing through the inflow passage 11A can be made the same even after the valve body 14 is worn.

  Thus, according to the present embodiment, the outer peripheral side of the first shaft portion 14A adjacent to the opening / closing portion 14C of the valve body 14 is located between the first shaft portion 14A of the valve body 14 and the inflow passage 11A. Is shut off from the valve body housing chamber 12 when the valve body 14 is closed, communicates with the valve body housing chamber 12 when the valve body 14 is opened, and is in a non-contact state between the first shaft portion 14A and the inflow passage 11A. An annular space 14A2 is formed. Thereby, even when the first shaft portion 14A of the valve element 14 slides in the inflow passage 11A in accordance with the expansion and contraction of the piston rod 9, the space portion 14A2 and the inner peripheral surface of the inflow passage 11A are kept out of contact. Can be kept. As a result, even when the sliding portion 14A1 of the first shaft portion 14A wears due to the sliding of the valve body 14, the space portion 14A2 does not wear, so that a reduction in the damping force generated by the valve mechanism 13 can be suppressed.

  That is, even when the sliding portion 14A1 of the valve body 14 is worn, the space portion 14A2 is not worn, so that the flow area of the hydraulic fluid flowing from the inflow passage 11A toward the valve body accommodating chamber 12 is obtained. Is constant. Thus, the flow path area is constant before the valve element 14 is worn and after the valve element 14 is worn, so that the damping force generated by the valve mechanism 13 is also constant. As a result, even when the valve body 14 is worn, a decrease in the damping force can be suppressed.

  On the outer peripheral side of the first shaft portion 14A, a shaft portion passage 14A3 that connects the inflow passage 11A and the inside of the valve body accommodating chamber 12 via the space portion 14A2 is formed to extend in the axial direction. Thereby, the flow passage area of the working fluid flowing from the inflow passage 11A toward the valve body accommodation chamber 12 can be adjusted, so that a desired damping force can be generated.

  In addition, even if the valve element 14 is worn, a decrease in the damping force can be suppressed, so that the frequency of replacing the valve element 14 can be reduced. As a result, the valve element 14 can be used for a long period of time, so that the replacement cost of parts can be suppressed.

  In addition, in the said embodiment, the case where the space part 14A2 which keeps the 1st axial part 14A and the inflow path 11A in a non-contact state was provided in the outer peripheral side of the 1st axial part 14A was described as an example. However, the present invention is not limited to this, and may be configured, for example, as a modified example shown in FIG. That is, the space portion 21 may be provided on the outer peripheral side of the inflow passage 11A adjacent to the opening / closing portion 14C of the valve body 14. Thereby, a part of the first shaft portion 14A facing the space portion 21 can be kept in a non-contact state with the outer peripheral surface of the inflow passage 11A, so that abrasion does not occur and a decrease in damping force can be suppressed. .

  In the above embodiment, the bottom valve 7 is provided with the suction valve 7A, the piston 8 is provided with the check valve 8A, and the unidirectional flow of the hydraulic fluid from the rod-side oil chamber B toward the reservoir chamber A is performed. The type of the hydraulic shock absorber 1 has been described as an example. However, the present invention is not limited to this. For example, a check valve is provided for the bottom valve, the piston, and the rod guide, and the flow of the hydraulic fluid is in both the forward and reverse directions in both the extension stroke and the contraction stroke of the piston rod. The valve mechanism 13 may be provided in the bi-flow type hydraulic shock absorber.

  Further, in the above-described embodiment, the case where the valve mechanism 13 is provided in the flow path 11 arranged in the rod guide 10 has been described as an example. However, the present invention is not limited to this. For example, the valve mechanism may be provided in a flow path formed in a piston or in a flow path formed in a bottom valve.

  Further, in the above-described embodiment, an example has been described in which the hydraulic shock absorber 1 is mounted between the vehicle body and the bogie of the railway vehicle in a horizontal state. However, the present invention is not limited to this. For example, a configuration may be adopted in which the hydraulic shock absorber is mounted vertically between the body of the railway vehicle and the bogie.

  Furthermore, in the said embodiment, the case where the hydraulic shock absorber 1 is provided in a railroad vehicle was described as an example. However, the present invention is not limited to this. For example, shock absorbers used for four-wheeled vehicles and two-wheeled vehicles, shock absorbers used for various mechanical devices including general industrial equipment, shock absorbers used for buildings, and the like, objects to be shocked. Can be applied to various types of shock absorbers (cylinder devices) for shock absorbing.

  Next, the invention included in the embodiment will be described. According to the present invention, the space portion is formed on the outer peripheral side of the sliding shaft portion, adjacent to the opening / closing portion of the valve body. Thus, the space provided in the sliding shaft can be kept in non-contact with the inner peripheral surface of the inflow passage.

  Further, according to the present invention, the space portion is formed in the inflow passage adjacent to the opening / closing portion of the valve body. Thereby, the space provided in the inflow passage can be kept in non-contact with the outer peripheral surface of the sliding shaft.

  As the shock absorber based on the above-described embodiment, for example, the following embodiment can be considered.

  As a first aspect of the shock absorber, a piston filled with a working fluid, a piston inserted into the cylinder to partition the inside of the cylinder into a rod-side oil chamber and a non-rod-side oil chamber, A piston rod extending to the outside of the cylinder and connected to the cylinder, a flow path in which a flow of a working fluid is generated by sliding of the piston in the cylinder, and a flow path provided in the flow path as the piston moves. And a valve mechanism for adjusting a flow rate of the working fluid passing through the shock absorber. The valve mechanism is movably housed in a valve body housing chamber in which an inflow passage and an outflow passage of the working fluid are formed. A valve body for opening and closing the inflow passage of the valve body accommodating chamber; and a spring means for urging the valve body in a direction in which the inflow passage is closed. Slide inside A sliding shaft portion and an opening / closing portion for opening and closing the inflow passage are integrally formed, and the valve body is provided between the sliding shaft portion of the valve body and the inflow passage when the valve body is closed. An annular space is formed which is shut off from the accommodation chamber, communicates with the valve body accommodation chamber when the valve is opened, and maintains the sliding shaft and the inflow passage in a non-contact state. A shaft passage connecting the inflow passage and the valve body chamber through the space portion is formed on an outer peripheral side of the driving shaft portion so as to extend in the axial direction.

  As a second aspect, in the first aspect, the space portion is formed on an outer peripheral side of the sliding shaft portion adjacent to an opening / closing portion of the valve body.

  As a third aspect, in the first aspect, the space portion is formed in the inflow passage adjacent to an opening / closing portion of the valve body.

1 hydraulic shock absorber (buffer)
6. Inner cylinder (cylinder)
Reference Signs List 8 piston 9 piston rod 11 flow path 11A inflow passage 11B outflow passage 12 valve body storage chamber 13 valve mechanism 14 valve body 14A first shaft (sliding shaft)
14A2, 21 Space portion 14A3 Shaft passage 14C Expanding portion 15 Spring (spring means)

Claims (3)

A cylinder filled with working fluid,
A piston inserted into the cylinder to partition the inside of the cylinder into a rod-side oil chamber and a non-rod-side oil chamber;
A piston rod connected to the piston and extending out of the cylinder;
A flow path in which a flow of a working fluid is generated by sliding of the piston in the cylinder;
A valve mechanism provided in the flow path and adjusting a flow rate of a working fluid passing through the flow path with movement of the piston,
The valve mechanism includes:
A valve body movably received in the valve element housing chamber et al was provided to open and close the inlet passage of the valve body accommodating chamber between the inlet passage and the outlet passage of the working fluid,
Spring means for urging the valve body in a direction in which the inflow passage is closed,
The valve body has, at one end, a sliding shaft portion that slides in the inflow passage, and an opening / closing portion that opens and closes the inflow passage, are integrally formed,
A sliding portion that slides in the inflow passage is provided on one axial side of the sliding shaft portion of the valve body ,
Between the other end of the sliding shaft portion in the axial direction and the inflow passage, the valve body is shut off with respect to the valve body chamber when the valve body is closed, and is closed with respect to the valve body chamber when the valve body is opened. communication, and the non-sliding portion of the annular groove and said inflow passage and the sliding shaft in a non-sliding state over the entire circumference is formed,
A buffer portion is formed on the outer peripheral side of the sliding shaft portion so as to extend in the axial direction to communicate with the inflow passage and the valve body chamber through the non-sliding portion. vessel. The shock absorber according to claim 1, wherein the non-sliding part is formed on an outer peripheral side of the sliding shaft part adjacent to an opening / closing part of the valve body. The shock absorber according to claim 1, wherein the non-sliding portion is formed in the inflow passage adjacent to an opening / closing portion of the valve body.

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