JP2011179669A - Hydraulic shock absorber for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hydraulic shock absorber for a vehicle, which exhibits a required sufficient damping force with good responsiveness even in the early stage of a compression stroke without impairing ride comfort in a vehicle. <P>SOLUTION: The shock absorber D for the vehicle includes a partition member 5 partitioning an air chamber side chamber L2 into an anti-air chamber side pressure chamber L3 on the anti-air chamber side and an air chamber side pressure chamber L4 on the air chamber side; a communicating passage 6 serving for communication between the anti-air chamber side pressure chamber L3 and the air chamber side pressure chamber L4; a valve element 7 provided at an intermediate part of the communicating passage 6 to allow only the flow of liquid from the anti-air chamber side pressure chamber L3 toward the air chamber side pressure chamber L4 and to apply resistance to the flow of liquid from the anti-air chamber side pressure chamber L3 toward the air chamber side pressure chamber L4 when the piston speed in the compression stroke is a predetermined speed or lower; and a check valve 8 provided at an intermediate part of the communicating passage 6 in parallel with the valve element 7 to allow only the flow of liquid from the air chamber side pressure chamber L4 toward the anti-air chamber side pressure chamber L3. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an improvement of a hydraulic shock absorber for a vehicle.

  Conventionally, in a vehicle hydraulic shock absorber set to a single cylinder type, for example, a cylinder, a free piston that is slidably inserted into the cylinder and divides the inside of the cylinder into a liquid chamber and an air chamber, A piston that is slidably inserted into the cylinder and divides the liquid chamber into an anti-air chamber side chamber and an air chamber side chamber adjacent to the air chamber, and a rod having one end connected to the piston, Vibration is suppressed (see, for example, Patent Document 1).

  Further, in this single cylinder type hydraulic shock absorber for a vehicle, in the expansion / contraction stroke in which the piston moves in the axial direction with respect to the cylinder, the change in the volume in the cylinder when the rod enters and exits the cylinder. Compensation is achieved by increasing or decreasing the volume of the air chamber.

JP 08-159199 A (FIG. 1)

  By the way, the single cylinder type hydraulic shock absorber for a vehicle compresses the anti-air chamber side chamber where the piston does not face the air chamber and expands the volume of the opposite air chamber side chamber in the extending stroke. Flows from the compression-side anti-air chamber side chamber to the expansion-side air chamber-side chamber, resists the flow of this liquid and promotes the pressure increase in the compression-side anti-air chamber side chamber, It produces a difference and exerts a damping force that prevents extension by causing the differential pressure to act on the piston.

  On the other hand, in the stroke to be compressed, the single cylinder hydraulic shock absorber compresses the air chamber side chamber where the piston faces the air chamber and expands the volume of the opposite anti-air chamber side chamber. Therefore, the liquid flows from the air chamber side chamber on the compression side to the anti-air chamber side chamber on the expansion side, and resistance is given to the flow of the liquid to cause a difference in the pressure between the air chamber side chamber and the anti-air chamber side chamber. It exerts a damping force that prevents compression by acting on the piston.

  In this way, the single cylinder type hydraulic shock absorber for the vehicle compresses the anti-air chamber side chamber not facing the air chamber during the extension stroke, so that the anti-air is within the range allowed for the durability of the seal around the rod. The pressure in the chamber side chamber can be increased any number.

  On the other hand, during the compression stroke, the air chamber side chamber facing the air chamber is compressed and the air chamber itself is also compressed, but the bulk elastic modulus of the gas is smaller than the bulk elastic modulus of the liquid and Since the pressure rise is small, the pressure rise in the air chamber side chamber is also small, and further, the anti-air chamber side chamber not facing the air chamber is decompressed, so that the pressure field in the cylinder is lowered.

  As a result, the rigidity of the liquid column is lowered due to the influence of gas dissolved in the liquid.In particular, at the initial stage of switching from the expansion stroke to the compression stroke, the rising of the damping force during the compression stroke tends to be insufficient in time. In the case of a cylinder-type hydraulic shock absorber for a vehicle, further improvement in damping force generation response during the compression stroke is required.

  Therefore, the single cylinder type vehicle hydraulic shock absorber is designed to increase the damping force during the compression stroke by sealing the pressurized gas into the air chamber and maintaining the liquid in the cylinder in a constantly pressurized state. Has been given.

  However, when the pressure in the air chamber is increased, the pressure in the fluid chamber in the cylinder of the vehicle hydraulic shock absorber increases, and this pressure also acts on the oil seal that seals around the rod. The tightening force increases, the sliding resistance of the rod becomes excessive, and the smooth expansion and contraction of the single cylinder type hydraulic shock absorber is impeded. Especially when used in vehicle applications, the occupant feels jerky. This can hinder ride comfort in the vehicle.

  Therefore, the present invention was devised to improve the above-described problems, and the object of the present invention is to provide sufficient responsiveness even in the initial stage of the compression stroke without impairing the ride comfort in the vehicle. It is an object of the present invention to provide a vehicle hydraulic shock absorber that can exhibit a damping force.

  In order to solve the above-described problems, the problem solving means of the present invention includes a container, a free piston that divides the container into a liquid chamber filled with liquid and an air chamber filled with gas, and a slide inside the container. A hydraulic pressure comprising a piston that is movably inserted to partition the liquid chamber into an anti-air chamber side chamber and an air chamber side chamber adjacent to the air chamber, and a rod that is movably inserted into the container and connected to the piston. In the shock absorber, a partition member that further divides the air chamber side chamber into an anti air chamber side pressure chamber and an air chamber side pressure chamber on the anti air chamber side, an anti air chamber side pressure chamber, and an air chamber side pressure chamber; And a communication passage that is provided in the middle of the communication passage and allows only a liquid flow from the pressure chamber side pressure chamber to the pressure chamber side pressure chamber, and the piston speed in the compression stroke is equal to or lower than a predetermined speed. A valve element that provides resistance to the flow of liquid from the pressure chamber to the pressure chamber, and in the middle of the communication path Characterized in that in parallel with the element provided with a check valve that allows the air chamber side pressure chamber only the flow of liquid towards the reaction gas chamber side pressure chamber.

  According to the single cylinder type hydraulic shock absorber of the present invention, when the piston speed in the compression stroke is equal to or lower than the predetermined speed, the flow passage area is limited to be small, so that the liquid in the anti-air chamber side pressure chamber moves to the air chamber side pressure chamber. The pressure in the reaction chamber side pressure chamber is quickly increased to suppress the decrease in pressure field, and the damping force at the initial stage of switching from the expansion stroke to the compression stroke or when the piston speed is low during the compression stroke It is possible to eliminate the tendency of the rise of the time to be insufficient, and the damping force generation responsiveness is improved.

  In addition, since there is no need to increase the pressure in the air chamber, the pressure in the container of the hydraulic shock absorber for the vehicle does not become excessively high, and there is no fear that the tightening force of the seal member that seals around the rod will increase. It does not disturb the ride comfort of the vehicle by making the vehicle occupant perceive a jerky feeling.

  Therefore, according to the hydraulic shock absorber for a vehicle of the present invention, a necessary and sufficient damping force can be exhibited with good responsiveness even in the initial stage of the compression stroke without impairing the ride comfort in the vehicle.

It is a longitudinal cross-sectional view of the hydraulic shock absorber for vehicles in one embodiment. It is a partially expanded longitudinal cross-sectional view of the hydraulic shock absorber for vehicles in one embodiment. It is an enlarged vertical sectional view of a valve element and a check valve of a hydraulic shock absorber for a vehicle in an embodiment. It is a figure explaining the time change of the damping force of the hydraulic buffer for vehicles in one embodiment.

  The present invention will be described below based on the embodiments shown in the drawings. As shown in FIG. 1 and FIG. 2, the vehicle hydraulic shock absorber D in one embodiment includes a container 1, a liquid chamber L filled with liquid in the container 1, and an air chamber G filled with gas. A free piston 2 that is partitioned into a container 1, a piston 3 that is slidably inserted into the container 1, and divides the liquid chamber L into an anti-air chamber side chamber L 1 and an air chamber side chamber L 2 adjacent to the air chamber G; A rod 4 that is movably inserted into the piston 3 and connected to the piston 3, and a partition that further divides the air chamber side chamber L2 into an anti air chamber side pressure chamber L3 and an air chamber side air chamber side pressure chamber L4. A member 5, a communication passage 6 communicating the anti-air chamber side pressure chamber L 3 and the air chamber side pressure chamber L 4, a valve element 7 provided in the middle of the communication passage 6, and a valve element 7 in the middle of the communication passage 6. A check valve 8 is provided in parallel, and the container 1 is connected to the vehicle body by connecting the rod 4 to the vehicle axle and the vehicle 1 between the vehicle body and the axle. Is set to upright interposed stand is intended to suppress the vibration of the vehicle body.

  Hereinafter, each member will be described in detail. The container 1 has a cylinder 10 into which a piston 3 is slidably inserted, and an axis W that does not coincide with the axis V of the cylinder 10, a free piston 2 is slidably inserted, and a partition member 5 is accommodated. And a cylinder 11.

  More specifically, the cylinder 10 has a cylindrical shape, and a rod guide 12 that rotatably supports the rod 4 is fitted to the upper end in FIG. A seal member 13 is laminated above the rod guide 12 and is fastened and fixed to the cylinder 10 together with the rod guide 12 by a cap 14 that is screwed onto the outer periphery of the upper end of the cylinder 10 in FIG. The seal member 13 includes a lip portion 13a that is in sliding contact with the outer periphery of the rod 4 and an outer peripheral seal portion 13b that is in close contact with the rod guide 12, so that the space between the rod 4 and the rod guide 12 is tightly sealed. Yes.

  The sub-cylinder 11 has a cylindrical shape, and has an axis W that is inclined with respect to the axis V of the cylinder 10, and a cylindrical socket 15 that is vertically suspended near the right end in FIG. And a bracket 16 for suspending the sub-cylinder 11 to a member on the axle side of the vehicle. The sub cylinder 11 and the socket 15 communicate with each other through a through hole 17 that obliquely penetrates the thickness of the sub cylinder 11 from the base of the socket 15.

  The sub cylinder 11 is coupled to the cylinder 10 by screwing the socket 15 to the lower end of the cylinder 10. When the cylinder 10 and the sub-cylinder 11 are coupled in this manner, the socket 15 and the bracket 16 are disposed on the cylinder 10 on the axis V, and the sub-cylinder 11 is coupled to the cylinder 10 in an inclined posture. In addition, the inside of the cylinder 10 is communicated with the sub cylinder 11 through the through hole 17, and both ends of the sub cylinder 11 are sealed with lids 18 and 19.

  A piston 3 fixed to the tip of the rod 4 is slidably inserted into the cylinder 10, and the free piston 2 is inserted into the insertion portion 11a on the left side in FIG. The liquid chamber L is formed in a part of the cylinder 10 and the sub cylinder 11 so as to be slidable. The liquid chamber L is filled with a liquid such as hydraulic oil, for example. . On the other hand, in the sub cylinder 11, an air chamber G is formed by the free piston 2, and the air chamber G and the liquid chamber L are partitioned by the free piston 2. The air chamber G is filled with, for example, an inert gas such as nitrogen at a predetermined pressure. In the air chamber G, the free piston 2 moves up and down in the drawing relative to the cylinder 10 when the vehicle hydraulic shock absorber D expands and contracts to expand and contract its volume, so that the rod 4 moves into the cylinder 10. The volume change of the liquid chamber L due to entering and exiting is compensated.

  Also, the piston 3 slidably inserted into the cylinder 10 divides the inside of the cylinder 10 into an anti-air chamber side chamber L1 and an air chamber side chamber L2 adjacent to the air chamber G. A partition member 5 is fitted in the right-side accommodation portion 11b in FIG. 1, and the air chamber side chamber L2 is separated from the air chamber side pressure chamber L3 and the air chamber side by the partition member 5. It is partitioned off from the air chamber side pressure chamber L4. The opening end on the sub cylinder 11 side of the through hole 17 is provided closer to the right end of the sub cylinder 11 than the housing position of the partition member 5, and the space on the right end side of the sub cylinder 11 from the partition member 5 is the cylinder 10. A part of the anti-air chamber side pressure chamber L3 is formed in communication with the inside.

  Further, the sub cylinder 11 is fixed in an inclined posture with respect to the cylinder 10, and the counter air chamber side pressure chamber L <b> 3 formed in the sub cylinder 11 is disposed below the air chamber G. The total length x on the air chamber G side of the sub cylinder 11 is set to be longer than the total length y on the counter air chamber side pressure chamber side L3 of the sub cylinder 11 when viewed from the coupling position. Therefore, it is considered that the sub-cylinder 11 is not disposed around the bracket 16 that is a mounting member for the member on the axle side, and the sub-cylinder 11 becomes an obstacle when the vehicle hydraulic shock absorber D is attached to the axle side. Or interference with other members. Further, the total length x on the air chamber G side of the sub cylinder 11 is set to be longer than the total length y on the counter air chamber side pressure chamber side L3 of the sub cylinder 11 when viewed from the coupling position of the sub cylinder 11 to the cylinder 10. Therefore, the through-hole 17 can be shortened, the overall length of the through-hole installation location of the sub-cylinder 11 that must be thicker than necessary strength can be shortened, and the vehicle hydraulic shock absorber D can be reduced in weight. be able to.

  In addition to this, in the case of this embodiment, the outer diameter of the accommodating portion 11b which is the accommodating side of the partition member 5 on the right side in FIG. It is set to be equal to or smaller than the diameter, and the axis W2 in the accommodating portion 11b of the partition member 5 is offset upward with respect to the axis W1 in the insertion portion 11a of the free piston 2. Thus, since the accommodating part 11b which is the end part by the side of the anti-air chamber side pressure chamber L3 which is in the sub cylinder 11 and is arrange | positioned below the air chamber G is offset upward, from the circumference | surroundings of the bracket 16 The sub-cylinder 11 can be further moved away, and the sub-cylinder 11 does not get in the way when mounting the vehicle hydraulic shock absorber D on the axle side, and does not interfere with other members.

  Further, the free piston 2 is inserted into the insertion portion 11a of the sub-cylinder 11, but the liquid chamber L is further increased by the step portion 11c formed at the boundary between the inner periphery of the storage portion 11b and the inner periphery of the insertion portion 11a. In order to avoid interference with a partition member 5 described later, the movement is restricted so that the liquid chamber L is not compressed.

  The piston 3 includes an attenuation passage 20 that communicates the anti-air chamber side chamber L1 and the air chamber side chamber L2, and the attenuation passage 20 includes an attenuation valve 21 that resists the flow of liquid that passes through the attenuation passage 21. When the vehicle hydraulic shock absorber D expands or contracts, it resists the flow of liquid that moves from the anti-air chamber side chamber L1 to the air chamber side chamber L2 or from the air chamber side chamber L2 to the anti-air chamber side chamber L1. Thus, a difference is generated between the pressures of the reaction chamber side chamber L1 and the air chamber side chamber L2.

  It should be noted that the damping valve 21 only needs to provide resistance to the flow of the liquid when the liquid passes and cause a predetermined pressure loss. Specifically, for example, a damping valve such as an orifice or a leaf valve is employed. can do. In addition, an attenuation passage that allows only the flow from the anti-air chamber side chamber L1 to the air chamber side chamber L2 and an attenuation passage that allows only the flow from the air chamber side chamber L2 to the anti-air chamber side chamber L1 are provided. A configuration in which a damping valve is provided may be employed, and the damping passage may be provided in the rod 4 or outside the cylinder 10 in addition to the piston 3.

  As shown in FIGS. 1 and 2, the partition member 5 includes a communication path 6 and an annular valve seat 22. Specifically, the partition member 5 includes a disk section 23 including the communication path 6 and the annular valve seat 22, and a disk section. 23 is provided with a shaft portion 24a rising from 23.

  The disk portion 23 is a ring-shaped communication passage 6 composed of a plurality of through-holes penetrating the wall thickness in the axial direction, and is an end portion on the air chamber side pressure chamber L4 side and surrounds all of the through-holes. An annular valve seat 22 surrounding the passage 6 is provided.

  The shaft portion 24 a is configured by a bolt member 24 inserted through the inner periphery of the disk portion 23. Specifically, the bolt member 24 is inserted into the inner periphery of the disk portion 23 and contacts the shaft portion 24a in which the screw portion 24b is formed at the tip, and the end portion of the disk portion 23 on the side opposite to the air chamber side pressure chamber L3. And a head portion 24c having a diameter larger than that of the contacting shaft portion 24a. The shaft portion 24a may be directly formed integrally with the disk portion 23.

  In the case of this embodiment, the partition member 5 includes a case 25 that is screwed onto the screw portion 24b of the shaft portion 24a, and the case 25 includes an inner cylinder 25a that is screwed onto the shaft portion 24; A flange 25b provided on the outer periphery of the inner cylinder 25a, an outer cylinder 25c that rises from the outer periphery of the flange 25b and fits on the outer periphery of the disk part 23, and a plurality of holes 25d provided in the outer cylinder 25c. Has been. In addition to the screw portion 24b of the shaft portion 24a, a screw member 33 is screwed into the inner cylinder 25a from the side opposite to the bolt member 24, and the tip of the screw member 33 is at the tip of the shaft portion 24a. The bolt members 24 and the case 25 are prevented from coming loose.

  When the case 25 is screwed to the shaft portion 24a, the disk portion 23 is sandwiched between the bolt member 24 and the case 25, and these members are integrated.

  Further, a step portion 25e is provided on the outer periphery of the outer cylinder 25c of the case 25, and this step portion 25e is engaged with a step portion 11d provided on the inner periphery of the accommodating portion 11b in the sub cylinder 11. When the lid 19 is screwed to the open end of the 11 accommodating portion 11b, the partition member 5 is sandwiched by the lid 19 and the step portion 11d so as to be integrated with the sub cylinder 11. As described above, when the partition member 5 is accommodated in the sub-cylinder 11, the flow of the liquid that passes through the through-hole 17 and flows into the sub-cylinder 11 or passes through the communication path 6 and escapes to the through-hole 17 is disc. The chamfer 23a is chamfered by chamfering the outer periphery of the lower end in FIG. 2 which is the end on the side of the pressure chamber L3 of the disk portion 23 so as not to be blocked by the annular gap between the portion 23 and the sub cylinder 11. Is provided. Thus, by providing the chamfered portion 23a on the outer periphery of the counter air chamber side pressure chamber L3 side end of the disk portion 23, it becomes easy to secure the flow path area, so that the total length of the sub cylinder 11 can be shortened. it can.

  Subsequently, as shown in FIGS. 2 and 3, the valve element 7 has an annular valve seat 22 provided on the outer periphery of the open end of the communication path 6 of the partition member 5, and a disk portion 23 in the partition member 5. A valve body 26 that is separable in the direction and detachably seats on the annular valve seat 22, and urges the valve body 26 toward the annular valve seat 22 and compresses the piston body when the piston speed in a contraction stroke exceeds a predetermined speed. 26, and a spring 27 as an urging means for allowing the partition member 5 to be separated from the disk portion 23.

  More specifically, the valve body 26 is annular and is mounted on the outer periphery of the shaft portion 24 a so as to be movable in the axial direction. The valve body 26 includes a plurality of through holes 26 a on a concentric circle, and the outer periphery contacts the annular valve seat 22. Touching. Further, between the valve body 26 and the disk portion 23, an annular spring member 28, a spacer 29, and a check valve body 30 that are attached to the outer periphery of the shaft member 24a are interposed in order from the disk portion 23 side. Further, on the air chamber side pressure chamber L4 side of the valve body 26, the outer diameter is smaller than that of the valve body 26 and one end of the spring 27 is seated, as well as the outer periphery of the shaft member 24a. An annular spacer 32 is interposed. The valve body 26 and the spacer 32 are attached to the outer periphery of the shaft portion 24a other than the screw portion 24b so that the movement of the valve body 26 in the axial direction is not hindered. The number of the through-holes 26a is arbitrary, but the resistance of the flow of the liquid that the entire opening area of the through-holes 26a passes through to provide resistance to the air chamber side pressure chamber L3 and the air chamber side air chamber side pressure. The chamber L4 may be set so as not to give a differential pressure that cannot be ignored when exhibiting a damping force.

  Further, in this case, the spring 27 is a coil spring, the inner diameter is set larger than the outer diameter of the spacer 32 described above, and the inner peripheral side of the valve body 26 and the flange portion 25b of the case 25 described above. The valve body 26 is always urged toward the annular valve seat 22 side. The case 25 also functions as a spring receiver that maintains the spring 27 in a compressed state, and the initial load (preload) of the spring 27 may be adjusted by inserting a washer or the like in the flange portion 25b. .

  Although the pressure in the anti-air chamber side pressure chamber L3 exceeds the pressure in the air chamber side pressure chamber L4, the outer periphery of the valve body 26 bends until the valve body 26 overcomes the urging force of the spring 27 and moves backward. The communication passage 6 is opened by separating from the annular valve seat 22 so that the difference between the pressure in the anti-air chamber side pressure chamber L3 and the pressure in the air chamber side pressure chamber L4 is increased and the spring 27 is compressed. As a result, the entire valve body 26 is separated from the disk portion 23 to increase the clearance between the annular valve seat 22 and open the communication passage 6. The amount of retraction when the valve body 26 retracts away from the disk portion 23 is determined by the axial gap between the spacer 32 and the inner cylinder 25a of the case 25. The thickness of the spacer 32 or the inner cylinder 25a Determined by axial length. Further, in the present embodiment, the shaft portion 24a is constituted by the bolt member 24, the case 25 functions as a nut, and the valve body 26 moves in the axial direction on the outer periphery of the shaft portion 24a. 25c is provided, and the disc portion 23 is sandwiched between the bolt member 24 and the case 25, but the shaft portion 24a is fixed to the disc portion 23 by other means or directly provided on the disc portion 23. In this case, the case 25 only needs to function as a spring receiver for the spring 27, and therefore it is not necessary to provide the outer cylinder 25c.

  As shown in FIGS. 2 and 3, the check valve 8 is attached to the through hole 26a provided in the valve body 26 and the shaft portion 24a, and is stacked on the disk portion 23 side end portion of the valve body 26. An annular check valve body 30 that opens and closes the through hole 26a, and a spring member 28 that is attached to the shaft portion 24a and serves as a biasing means that biases the check valve body 30 toward the valve body 26. It is configured. The check valve body 30 is sandwiched between a spring 27 and a spacer 29, and the outer edge of the spacer 29 whose outer diameter is set smaller than the inscribed circle of the plurality of through holes 26a provided in the valve body 26 is bent. The outer periphery is allowed to bend as a starting point.

  The spring member 28 includes an annular seat portion 28a attached to the outer periphery of the shaft portion 24a, and a plurality of thin plate spring portions 28b extending radially from the outer periphery of the seat portion 28a toward the check valve body 30. Thus, the elastic force is exerted by the bending of the thin plate spring portion 28b, and the check valve body 30 is urged toward the valve body 26. The number of the thin leaf spring portions 28b is arbitrary, but it is preferable to provide three or more at equal intervals for the purpose of biasing the check valve body 30 without bias. The urging force for urging the check valve body 30 of the spring member 28 can be adjusted not only by the elastic force and the number of the thin plate spring portions 28b but also by the axial thickness of the spacer 29.

  The check valve 8 is configured such that the check valve body 30 bends the outer periphery against the flow of liquid passing through the through hole 26a from the air chamber side pressure chamber L4 toward the anti-air chamber side pressure chamber L3. On the contrary, the flow of liquid in the direction from the anti-air chamber side pressure chamber L3 to the air chamber side pressure chamber L4 is in close contact with the valve body 26 to close the through hole 26a. With respect to the flow of liquid in the direction from the anti-air chamber side pressure chamber L3 to the air chamber side pressure chamber L4, the valve body 26 in the valve element 7 is bent or separated from the partition member 5, and the communication passage 6 is passed through. Although the check valve element 30 is opened, the check valve element 30 is in close contact with the valve element 26 and bends together with the valve element 26, so that the flow of the liquid is not hindered.

  In this way, the valve element 7 that allows only the flow of liquid from the air chamber side pressure chamber L3 to the air chamber side pressure chamber L4, and the flow of liquid from the air chamber side pressure chamber L4 to the anti air chamber side pressure chamber L3. The check valve 8 that allows only the pressure is provided in parallel to the communication path 6. The check valve 8 utilizes a through hole 26a provided in the valve element 26 of the valve element 7, and the check valve 8 and the valve element 7 are inseparable, but these should be provided completely separately. Also good. However, as described above, the valve body 26 of the valve element 7 is provided with a through hole 26a, and is attached to the shaft portion 24a and is stacked on the partition member 5 side end portion of the valve body 26 so as to form the through hole 26a. The check valve 8 is configured by an annular check valve body 30 that opens and closes and a spring member 28 that is attached to the shaft portion 24a and biases the check valve body 30 toward the valve body 26. Thus, there is an advantage that the check valve 8 can be configured compactly.

  Further, in the above description, the urging means in the valve element 7 and the check valve 8 are each a spring, but an elastic body may be used as long as the urging force can be exerted.

  Next, the operation of the vehicle hydraulic shock absorber D configured as described above will be described. First, when the vehicle hydraulic shock absorber D in which the piston 3 moves upward in FIG. 1 is extended, the anti-air chamber side chamber L1 is compressed by the rise of the piston 3, and the liquid in the anti-air chamber side chamber L1 is attenuated. It flows into the anti-air chamber side pressure chamber L3 of the lower air chamber side chamber L2 through the valve 21. At this time, since the rod 4 retracts from the cylinder 10, the volume of liquid in which the rod 4 retracts in the cylinder 10 is insufficient. Therefore, the check valve 8 opens the communication passage 6 to open the communication path 6. It is supplied from the chamber side pressure chamber L4 to the anti-air chamber side pressure chamber L3, and the free piston 2 moves in the direction of expanding the air chamber G and absorbs it.

  Although the check valve 8 is urged by the spring member 28, the urging force is set to be extremely weak. In this case, the liquid passes through the check valve 8 with almost no resistance, and the pressure on the air chamber side. The chamber L4 moves to the anti-air chamber side pressure chamber L3.

  Accordingly, during this extension stroke, the vehicle hydraulic pressure buffer D is operated by the expansion side corresponding to the pressure difference between the anti-air chamber side chamber L1 and the air chamber side chamber L2 generated when the liquid passes through the damping valve 21 provided in the piston 3. Demonstrates damping force.

  On the other hand, when the vehicle hydraulic shock absorber D in which the piston 3 moves downward in FIG. 1 is compressed, the anti-air chamber side pressure chamber L3 in the air chamber side chamber L2 is compressed by the lowering of the piston 3, and the anti-air chamber is compressed. The liquid in the side pressure chamber L3 flows into the upper anti-air chamber side chamber L1 through the damping valve 21. At that time, since the rod 4 enters the cylinder 10, the volume of liquid into which the rod 4 enters in the cylinder 10 becomes excessive, so that the valve element 7 opens the communication path 6 in the excess liquid. The air is discharged from the anti-air chamber side pressure chamber L3 to the air chamber side pressure chamber L4, and the free piston 2 moves in the direction of contracting the air chamber G and absorbs it.

  The valve element 7 includes a spring 27 as an urging unit that urges the valve body 26 toward the disk portion 23 of the partition member 5 when the piston speed in the compression stroke of the vehicle hydraulic shock absorber D is equal to or lower than a predetermined speed. The urging force to be pressed cannot be overcome by the action of the pressure in the compressed air chamber side pressure chamber L3 to push the valve body 26 against the urging force of the spring 27, and the spring 27 is not compressed. The valve body 26 is prevented from floating from the disk portion 23 on the inner periphery of the valve body 26, and only the outer periphery of the valve body 26 is bent away from the annular valve seat 22 to open the communication path 6. That is, until the initial load of the spring 27 exceeds the force that pushes the valve body 26 against the urging force of the spring 27 by the action of the pressure in the anti-air chamber side pressure chamber L3, the valve body 26 bends only at the outer periphery. The communication passage 6 is opened by separating from the annular valve seat 22.

  Furthermore, when the piston speed in the compression stroke of the vehicle hydraulic shock absorber D exceeds a predetermined speed, the valve body 26 is pushed against the biasing force of the spring 27 by the action of the pressure in the anti-air chamber side pressure chamber L3. When the force exceeds the initial load of the spring 27, the spring 27 is also compressed, and the entire valve body 26 is separated from the disk portion 23 to form a large annular gap between the valve body 26 and the annular valve seat 22, and the valve body The communication path 6 is opened with a much larger flow path area than when the communication path 6 is opened by bending only the outer periphery of 26.

  Thus, the valve element 7 restricts the flow path area to be small when the piston speed in the compression stroke of the vehicle hydraulic shock absorber D is equal to or lower than the predetermined speed, so that the liquid in the anti-air chamber side pressure chamber L3 is the air chamber. It becomes difficult to move to the side pressure chamber L4, and the pressure in the anti-air chamber side pressure chamber L3 is quickly increased.

  That is, the vehicle hydraulic pressure buffer D quickly increases the pressure in the anti-air chamber side pressure chamber L3 and suppresses the decrease in the pressure field in the anti-air chamber side chamber L1 and the anti-air chamber side pressure chamber L3. However, since the damping force on the compression side can be exerted, the tendency to start up the damping force in the initial stage when switching from the expansion stroke to the compression stroke or when the piston speed is low during the compression stroke can be eliminated. Damping force generation responsiveness is improved. That is, in the conventional single cylinder type hydraulic shock absorber, as shown by the broken line in FIG. 4, the responsiveness of the generation of the damping force tends to be delayed at the initial stage of switching from the expansion stroke to the compression stroke. In the hydraulic shock absorber D, as shown by the solid line in FIG. 4, the delay in the generation response of the damping force can be eliminated. FIG. 4 shows the response of the damping force when the piston speed is switched from the expansion stroke to the compression stroke and the piston speed in the compression direction gradually increases.

  Further, since there is no need to increase the pressure in the air chamber, the pressure in the container 1 of the vehicle hydraulic shock absorber D does not become excessively high, and the tightening force of the seal member 13 that seals around the rod 4 increases. There is no worry, and the rider feels a jerky feeling without disturbing the ride comfort in the vehicle.

  Therefore, according to the vehicle hydraulic shock absorber D of the present invention, the necessary and sufficient damping force can be exhibited with good responsiveness even in the initial stage of the compression stroke without impairing the ride comfort in the vehicle. The predetermined speed at which the flow passage area of the valve element 7 increases can be arbitrarily determined so as to be suitable for the vehicle.

  On the other hand, when the piston speed exceeds a predetermined speed, the flow path area increases, the resistance decreases, and the liquid moves from the anti-air chamber side pressure chamber L3 to the air chamber side pressure chamber L4 without being limited as much as the difference. In this case, the damping force equivalent to that of the conventional single cylinder type hydraulic shock absorber is exhibited.

  In the above description, the cylinder 10 and the sub-cylinder 11 are coupled in a T shape. However, the sub-cylinder 11 may be provided beside the cylinder 10 or the cylinder 10 and the sub-cylinder 11 may be connected to the hose. It is also possible to adopt a configuration that connects them. Further, the container 1 may be realized by other configurations besides the above-described cylinder 10 and sub-cylinder 11.

  This is the end of the description of the embodiment of the present invention, but the scope of the present invention is of course not limited to the details shown or described.

  The hydraulic shock absorber for a vehicle according to the present invention can be used for a vibration damping application of a vehicle.

DESCRIPTION OF SYMBOLS 1 Container 2 Free piston 2a Recessed part 3 in free piston 3 Piston 4 Rod 5 Partition member 6 Communication path 7 Valve element 8 Check valve 10 Cylinder 11 Subcylinder 11a Insertion part 11b in subcylinder Storage part 11c in subcylinder, 11d Stage in subcylinder Portion 12 Rod guide 13 Seal member 13a Lip portion 13b of seal member Peripheral seal portion 14 of seal member Cap 15 Socket 16 Bracket 17 Through holes 18, 19 Lid 20 Damping passage 21 Damping valve 22 Annular valve seat 23 Disc portion 23a Disc portion Chamfered portion 24 Bolt member 24a Shaft portion 24b Screw portion 24c Head portion 25 Case 25a Inner cylinder 25b in case Hook portion 25c in case Outer cylinder 25d in case Hole 25e in case Step portion 33 Screw member 26 Valve body 26a Through hole 27 Spring 28 as urging means Spring member 28a Seat portion 28b in spring member Thin plate spring portions 29 and 32 in spring member Spacer 30 Check valve body 31 Spacer D Vehicle fluid Pressure buffer G Air chamber L Liquid chamber L1 Anti-air chamber side chamber L2 Air chamber side chamber L3 Anti-air chamber side pressure chamber L4 Air chamber side pressure chamber V Cylinder axis W Sub-cylinder axis W1 Sub-cylinder axis W2 Sub-axis Axis in cylinder housing

Claims (7)

A container, a free piston that divides the container into a liquid chamber filled with liquid and a gas chamber filled with gas, and a liquid chamber that is slidably inserted into the container to convert the liquid chamber into an anti-air chamber side chamber and an air chamber In a hydraulic shock absorber provided with a piston that is divided into adjacent air chamber side chambers and a rod that is movably inserted into a container and connected to the piston, the air chamber side chamber is further separated from the air chamber side. A partition member that partitions the side pressure chamber and the air chamber side pressure chamber, a communication path that connects the anti-air chamber side pressure chamber and the air chamber side pressure chamber, and an anti-air Only the flow of liquid from the chamber side pressure chamber to the air chamber side pressure chamber is allowed, and the piston speed in the compression stroke is less than a predetermined speed, and resistance is given to the liquid flow from the counter air chamber side pressure chamber to the air chamber side pressure chamber. The valve element and the valve element in the middle of the communication path are headed from the air chamber side pressure chamber to the counter air chamber side pressure chamber. Vehicle hydraulic shock absorber is characterized by providing a check valve which allows only the flow of the body. The partition member includes the communication passage, and the valve element includes an annular valve seat provided on an outer periphery of an opening end of the communication passage of the partition member, and a valve body that is separable from the partition member and is attached to and detached from the annular valve seat. And a biasing means that biases the valve body toward the annular valve seat and compresses the piston when the piston speed in the contraction stroke exceeds a predetermined speed to allow the valve body to be separated from the partition member. The vehicle hydraulic shock absorber according to claim 1. The partition member includes a disk portion including a communication path and an annular valve seat, and a shaft portion rising from the disk portion, and the valve body in the valve element is annular and is slidably mounted on the outer periphery of the shaft portion. The check valve includes a through hole provided in the valve body, an annular check valve body that is attached to the shaft portion and stacked on the partition member side end of the valve body to open and close the through hole, and The vehicle hydraulic shock absorber according to claim 2, further comprising an urging means attached to the shaft portion to urge the check valve body toward the valve body. The container includes a cylinder into which the piston is slidably inserted, and a sub-cylinder having an axis that does not coincide with the axis of the cylinder and into which the free piston is slidably inserted and the partition member is accommodated. The vehicle hydraulic shock absorber according to any one of claims 1 to 3. 5. The vehicular hydraulic shock absorber according to claim 4, wherein the vehicular hydraulic shock absorber is set upright, and a sub-cylinder is coupled to a lower end of the cylinder in an inclined posture. A counter air chamber side pressure chamber formed in the sub cylinder is provided below the air chamber, and the sub cylinder's total air chamber side pressure as viewed from the coupling position of the sub cylinder to the cylinder is the counter cylinder's counter air chamber side pressure. 6. The vehicle hydraulic shock absorber according to claim 5, wherein the vehicle hydraulic shock absorber is longer than the overall length on the chamber side. The sub cylinder has a cylindrical shape, and the outer diameter of the housing side of the partition member in the sub cylinder is set to be equal to or smaller than the outer diameter of the insertion side of the free piston, and the partition member is accommodated with respect to the axis on the insertion side of the free piston. The vehicle hydraulic shock absorber according to any one of claims 4 to 6, wherein an axial line on the side is offset upward.

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