JP2009008150A - Damping force adjusting structure of hydraulic shock absorber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a back collar on the outer periphery of a valve stopper for a damping valve and provide a back pressure chamber on the back side of the damping valve without increasing the processing accuracy of the valve stopper and the backup collar. Make it controllable.
In a damping force adjusting structure of a hydraulic shock absorber, a valve stopper is provided on the back surface of a damping valve, a backup collar that slides through a sliding gap is provided on the valve stopper, and A plate spring 56 is provided on the back surface, and the back pressure chamber 52 is formed by pressing the front surface of the backup collar 54 against the damping valve 34 by the plate spring 56, and a slit 56 A is provided in the plate spring 56 that holds the backup collar 54. The amount of pressure leak in the back pressure chamber 52 that passes through the sliding gap of the valve stopper 23 is controlled by the slit 56A of the leaf spring 56.
[Selection] Figure 3

Description

  The present invention relates to a damping force adjusting structure for a hydraulic shock absorber.

  As described in Patent Document 1, as a damping force adjustment structure of the hydraulic shock absorber, a back pressure chamber is provided on the back side of the damping valve of the hydraulic shock absorber, and the damping force can be adjusted by controlling the pressure of the back pressure chamber. There is something to do. In Patent Document 1, a valve stopper (case) is provided on the back surface of the damping valve, a backup collar (seal member) that slides fluid-tightly is provided on the inner periphery of the valve stopper, a leaf spring is provided on the back surface of the backup collar, A back pressure chamber is formed by pressing the front face of the backup collar against the damping valve by a spring.

In the damping force adjustment structure of Patent Document 1, by controlling the pressure in the back pressure chamber that presses the damping valve in the closing direction, the damping force can be adjusted smoothly and without delay in a stepless manner over a large and small range. Adjustable from extremely low speed range.
JP-A-8-4818

  In the damping force adjusting structure described in Patent Document 1, the backup collar is slid in a liquid-tight manner with respect to the valve stopper to prevent pressure leakage from the back pressure chamber, thereby stably maintaining the damping force characteristic of the damping valve. At the same time, when the pressure in the back pressure chamber reaches a certain level or more, the pressure control valve provided in the back pressure flow path communicating with the back pressure chamber is opened to repeat the control of the pressure in the back pressure chamber. The pressure above a certain level is released.

  Therefore, in the damping force adjusting structure described in Patent Document 1, it is necessary to slide the backup collar against the valve stopper in a liquid-tight manner to prevent pressure leakage from the back pressure chamber. Need to increase accuracy.

  An object of the present invention is to provide a back collar on the outer periphery of a valve stopper for a damping valve, and to provide a back pressure chamber on the back side of the damping valve without increasing the processing accuracy of the valve stopper and the backup collar. It is to be able to control the pressure.

  According to a first aspect of the present invention, there is provided a damping force adjusting structure for a hydraulic shock absorber in which a back pressure chamber is provided on the back side of the damping valve of the hydraulic shock absorber, and the damping force can be adjusted by controlling the pressure of the back pressure chamber. A valve stopper is provided on the back of the damping valve, a backup collar that slides through the sliding gap is provided on the valve stopper, a leaf spring is provided on the back of the backup collar, and the front of the backup collar is pressed against the damping valve by the leaf spring. The back pressure chamber is formed, and a slit is provided in the leaf spring that holds the backup collar, and the amount of leakage of the pressure in the back pressure chamber that passes through the sliding gap between the backup collar and the valve stopper is controlled by the leaf spring slit. It is.

  According to a second aspect of the present invention, in the first aspect of the present invention, the backup collar is provided with a pressure receiving portion that receives the pressure of the back pressure chamber, and the backup collar is pushed down by a pressure higher than a certain level.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, an oil sump is provided on at least one of the sliding surfaces of the valve stopper and the backup collar.

(Claim 1)
(a) A valve stopper is provided on the back of the damping valve, a backup collar that slides through the sliding gap is provided on the valve stopper, a leaf spring is provided on the back of the backup collar, and the front of the backup collar is attenuated by the leaf spring. To form a back pressure chamber, and to provide a slit in the leaf spring that holds the backup collar, and to control the amount of pressure leak in the back pressure chamber that passes through the sliding gap between the backup collar and the valve stopper. did. In this structure, the pressure in the back pressure chamber is extracted from the leak passage formed by the sliding gap between the backup collar and the valve stopper to leak, and the control of the pressure in the back pressure chamber can be repeated. The amount of pressure leak is stably controlled by the slits of the leaf springs, regardless of the dimensional accuracy of the sliding gaps affected by the processing accuracy of the backup collar and valve stopper. Without increasing the processing accuracy of the valve stopper and backup collar, the amount of pressure leakage and thus the pressure in the back pressure chamber can be stably controlled, and the damping force characteristics of the damping valve can be maintained stably.

(Claim 2)
(b) The backup collar is provided with a pressure receiving part that receives the pressure of the back pressure chamber, and the backup collar is pushed down by a pressure above a certain level. Therefore, when the pressure in the back pressure chamber increases, the backup collar is pushed down by the pressure acting on the pressure receiving portion provided in the backup collar, the damping valve backed up by the backup collar is opened, and the upper limit of the damping force (maximum) Damping force) can be set.

(Claim 3)
(c) An oil sump is provided on at least one of the sliding surfaces of the valve stopper and the backup collar. The slidability of the backup collar with respect to the valve stopper can be improved.

  1 is a cross-sectional view showing a damping force adjusting hydraulic shock absorber that drives a variable throttle valve by a solenoid, FIG. 2 is a cross-sectional view showing the damping force adjusting structure of FIG. 1, and FIG. 3 is an enlarged view of a main part of FIG. 4 is a state in which the throttle degree of the variable throttle valve is set to the closed side, (A) is a sectional view showing the compression side stroke, (B) is a sectional view showing the extension side stroke, and FIG. 5 shows the throttle degree of the variable throttle valve. FIG. 6A is a sectional view showing the compression side damping force, FIG. 6B is a sectional view showing the extension side damping force, and FIG. 6 is a damping force adjusting hydraulic buffer that drives the variable throttle valve by the motor. FIG. 7 is a cross-sectional view showing a modification of the damping force adjusting hydraulic shock absorber.

  As shown in FIGS. 1 and 2, the damping force adjusting hydraulic shock absorber 10 is a double-tube type composed of a double tube in which a cylinder 12 is built in a damper tube 11, and a piston rod 13 is inserted into the cylinder 12 to An axle side attachment portion is provided at the lower portion of the tube 11, and a vehicle body side attachment portion 14 is provided at the upper portion of the piston rod 13 to constitute a vehicle suspension device.

  The hydraulic shock absorber 10 has a suspension spring 16 interposed between a lower spring seat 15 on the outer periphery of the damper tube 11 and an upper spring seat (not shown) provided on the vehicle body side mounting portion 14 at the upper end portion of the piston rod 13. To do.

  The hydraulic shock absorber 10 clamps a rod guide 17, a bush 18, and an oil seal 19 for the piston rod 13 inserted into the cylinder 12 between the upper end crimped portion 11 </ b> A of the damper tube 11 and the upper end portion of the cylinder 12. It is fixed.

  The damping force adjusting hydraulic shock absorber 10 has a piston valve device 20 and a bottom valve device 40, and the damping force generated by them controls vibrations of the piston rod 13 due to the absorption of the impact force by the suspension spring 16. To do.

(Piston valve device 20)
The piston valve device 20 has a piston bolt 21 that is screwed and fixed to the outer periphery of the insertion end of the piston rod 13 into the cylinder 12, and a spacer 22, a valve stopper 23, a piston 24, a valve on the outer periphery of the piston bolt 21. The stopper 25, the cup 26, and the spacer 27 are inserted, and these are clamped and fixed between the base end step portion of the piston bolt 21 by the check valve housing 28 screwed to the piston bolt 21.

  The piston 24 is provided with an expansion-side flow path 31 and a pressure-side flow path 32, and the annular central portion of the disk valve-shaped expansion-side damping force valve 33 is sandwiched between the piston 24 and the valve stopper 25. The annular central portion of the pressure-side damping valve 34 having a disc valve shape is sandwiched between the two. That is, the piston valve device 20 divides the inside of the cylinder 12 into a rod side chamber 12A and a piston side chamber 12B by a piston 24. The rod side chamber 12A and the piston side chamber 12B are provided with an extension side channel 31 provided in the piston 24 and the extension side channel. The expansion side damping valve 33 that opens and closes 31, the pressure side flow path 32, and the pressure side attenuation valve 34 that opens and closes the pressure side flow path 32 communicate with each other.

  Therefore, at the time of extension, the oil in the rod side chamber 12A passes through the extension side flow passage 31 of the piston 24, bends and opens the extension side damping valve 33, is guided to the piston side chamber 12B, and generates an extension side damping force. At the time of compression, the oil in the piston side chamber 12B passes through the pressure side flow path 32 of the piston 24, bends and deforms the pressure side damping valve 34, is guided to the rod side chamber 12A, and generates a pressure side damping force.

(Bottom valve device 40)
In the hydraulic shock absorber 10, a gap between the damper tube 11 and the cylinder 12 is defined as a reservoir chamber 12C, and the interior of the reservoir chamber 12C is partitioned into an oil chamber and a gas chamber. The bottom valve device 40 includes a bottom piece 41 that partitions the piston side chamber 12B and the reservoir chamber 12C inside the cylinder 12 between the lower end portion of the cylinder 12 and the bottom portion of the damper tube 11, and the bottom portion of the damper tube 11. The space between the bottom piece 41 and the bottom piece 41 can be communicated with the reservoir chamber 12C through a flow path provided in the bottom piece 41.

  The bottom valve device 40 includes a disk valve 42 and a check valve 43 as bottom valves for opening and closing a pressure side channel 41A and an extension side channel (not shown) provided in the bottom piece 41, respectively.

  At the time of extension, the oil corresponding to the retraction volume of the piston rod 13 retreating from the cylinder 12 pushes the check valve 43 open, and enters the piston side chamber 12B from the reservoir chamber 12C via the expansion side flow path (not shown) of the bottom piece 41. To be replenished. During compression, the oil corresponding to the volume of the piston rod 13 entering the cylinder 12 is opened from the piston side chamber 12B through the pressure side flow path 41A of the bottom piece 41 by bending and deforming the disk valve 42 and pushed into the reservoir chamber 12C. Get the compression side damping force.

  In the hydraulic shock absorber 10, the piston rod 13 extends around the piston rod 13 located in the rod side chamber 12A of the cylinder 12 and on the rebound seat 46 fixed to the piston 24 side (lower side). A rebound rubber 47 that is compressed and deformed at the time of cutting (the most extended state of the hydraulic shock absorber 10) is provided.

  However, the hydraulic shock absorber 10 includes a damping force adjusting device 50 for adjusting the extension / pressure damping force of the piston valve device 30 as follows.

  As shown in FIG. 2, the damping force adjusting device 50 includes an extension side back pressure chamber on each of the back side of the extension side damping valve 33 with respect to the extension side channel 31 and the back side of the compression side damping valve 34 with respect to the pressure side channel 32. 51 and a compression side back pressure chamber 52 are provided. In this embodiment, each of the expansion side back pressure chamber 51 and the pressure side back pressure chamber 52 includes valve stoppers 25 and 23 provided on the back surfaces of the expansion side damping valve 33 and the pressure side damping valve 34, respectively, and these valve stoppers 25 and 23. The backup collars 53 and 54 are provided on the outer periphery of the backup collars 53 through a sliding gap, and the backup collars 53 and 54 are provided by leaf springs 55 and 56 (springs) provided on the back surfaces of the backup collars 53 and 54. The front face of 54 is urged and pressed against each of the expansion side damping valve 33 and the compression side damping valve 34. An annular central portion of the annular leaf spring 55 is clamped and fixed between the valve stopper 25 and the cup 26, and an outer edge portion of the leaf spring 55 comes into contact with the backup collar 53 in an elastic bent state. An annular central portion of the annular leaf spring 56 is clamped and fixed between the valve stopper 23 and the spacer 22, and an outer edge portion of the leaf spring 56 comes into contact with the backup collar 54 in an elastic bent state. At this time, the pressure receiving areas that the expansion side damping valve 33 and the compression side attenuation valve 34 respectively face the expansion side flow path 31 and the pressure side flow path 32 respectively face the expansion side back pressure chamber 51 and the pressure side back pressure chamber 52. It is preferable to make the pressure receiving area the same or slightly larger.

  The damping force adjusting device 50 is provided with a bypass passage 57 that bypasses the expansion side flow path 31 and the pressure side flow path 32 of the piston 24 and allows the rod side chamber 12A and the piston side chamber 12B to communicate with each other in the piston rod 13 (piston bolt 21). . The extension-side back pressure chamber 51 and the compression-side back pressure chamber 52 are communicated with an intermediate portion of the bypass passage 57. The bypass passage 57 communicates with the extension-side back pressure chamber 51 by sequentially communicating a hole 58A provided in the piston bolt 21, the inner peripheral annular groove 58B of the valve stopper 25, and the hole 58C. Further, the bypass passage 57 communicates with the pressure side back pressure chamber 52 by sequentially communicating a hole 59A provided in the piston bolt 21, an inner circumferential annular groove 59B of the valve stopper 23, and a hole 59C.

  The damping force adjusting device 50 is provided with one check valve 60 that allows the flow of oil from the piston side chamber 12B to the bypass passage 57 on the side of the bypass passage 57 that opens to the piston side chamber 12B. In this embodiment, the check valve housing 28 is liquid-tightly fitted in the recess of the cup 26, and the spacer 27 and the check valve 60 are interposed between the cup 26 and the check valve housing 28. An annular central portion of the check valve 60 made of an annular plate is clamped and fixed between the check valve housing 28 and the spacer 27, and the check valve 60 closes the flow paths 28A provided at a plurality of positions in the circumferential direction of the check valve housing 28. The oil in the piston side chamber 12B pushes open the check valve 60 from the flow path 28A of the check valve housing 28 and flows into the cup 26, and bypasses through the hole 61A, the annular groove 61B and the hole 61C of the spacer 27 and the piston bolt 21. It flows into the channel 57.

  The damping force adjusting device 50 is provided with a needle valve 70A of the variable throttle valve 70 on the side of the bypass passage 57 that opens to the rod side chamber 12A. The variable throttle valve 70 is connected to an actuator 71 provided on the vehicle body side mounting portion 14 at the upper end portion of the piston rod 13, is inserted through the hollow portion of the piston rod 13, and is provided near the upper end of the bypass passage 57 of the piston bolt 21. A needle valve 70A that contacts and separates from the valve seat 57A is provided at the tip. The needle valve 70A of the variable throttle valve 70 is linearly moved by the proportional solenoid of the actuator 71 so as to come into contact with and separate from the valve seat 57A of the bypass passage 57 and adjust the throttle degree with respect to the valve seat 57A. The pressures in the back pressure chamber 51 and the pressure side back pressure chamber 52 are controlled, so that the extension side damping force of the extension side damping valve 33 and the compression side damping force of the compression side damping valve 34 can be adjusted.

  The damping force adjusting device 50 is opened in each of the extension-side back pressure chamber 51 and the compression-side back pressure chamber 52 by a pressure higher than a certain level in the extension-side back pressure chamber 51 and the compression-side back pressure chamber 52. An extension side back pressure blow valve 81 and a pressure side back pressure blow valve 82 are provided to release the pressure in the pressure side back pressure chamber 52 to the piston side chamber 12B and the rod side chamber 12A, respectively. In this embodiment, each of the backup collars 53 and 54 constitutes an extension side back pressure blow valve 81 and a pressure side back pressure blow valve 82, respectively, as shown in FIG. That is, the backup collars 53 and 54 are provided with step-like pressure receiving portions 53A and 54A, respectively, whose diameters are increased at one end in the axial direction of the inner periphery so as to receive the pressures of the extension side back pressure chamber 51 and the pressure side back pressure chamber 52. The backup collars 53 and 54 are pushed down by a pressure higher than a certain level in the extension side back pressure chamber 51 and the pressure side back pressure chamber 52. When the pressure in the extension-side back pressure chamber 51 and the pressure-side back pressure chamber 52 rises, the backup collars 53, 54 are pushed down by the pressure acting on the pressure receiving portions 53A, 54A provided in the backup collars 53, 54. The extension side damping valve 33 and the compression side damping valve 34 backed up by 53 and 54 are opened, and the upper limit (maximum damping force) of the extension / pressure damping force can be set.

  The damping force adjusting device 50 is constituted by a sliding clearance between the valve stoppers 25 and 23 in each of the backup collars 53 and 54, as shown in FIG. Leak passages 53B and 54B for leaking the pressure of 52 are provided. The damping force adjusting device 50 is provided with slits 55A and 56A in the leaf springs 55 and 56 for holding the backup collars 53 and 54, and the extension side back pressure that passes through the sliding gap between the backup collars 53 and 54 and the valve stoppers 25 and 23. The amount of leakage in the chamber 51 and the pressure side back pressure chamber 52 is controlled by the slits 55A and 56A of the leaf springs 55 and 56. Each of the leaf springs 55 and 56 of the present embodiment is formed by laminating a plurality of thin plates, and slits 55A and 56A are provided at a plurality of circumferential positions on the outer edge of the innermost thin plate that is in direct contact with the backup collars 53 and 54. It is. The pressure of the back pressure chambers 51 and 52 is leaked by leaking from the leak passages 53B and 54B constituted by the sliding gaps between the backup collars 53 and 54 and the valve stoppers 25 and 23. Can be repeated. The amount of pressure leak in the back pressure chambers 51 and 52 is not dependent on the dimensional accuracy of the sliding gap, which affects the processing accuracy of the backup collars 53 and 54 and the valve stoppers 25 and 23, and the slits 55A and 56A of the leaf springs 55 and 56. Is controlled stably.

  As shown in FIG. 3, the damping force adjusting device 50 has two strips on the sliding surfaces on the outer periphery of the valve stoppers 25 and 23 in this embodiment, at least one of the sliding surfaces of the valve stoppers 25 and 23 and the backup collars 53 and 54. The oil reservoirs 25A and 23A comprising the annular grooves are provided to improve the slidability thereof.

Accordingly, the damping force adjusting device 50 operates as follows.
(A) When the variable throttle valve 70 sets the throttle degree of the bypass passage 57 to the closed side
(A-1) Compression side stroke (Fig. 4 (A))
The pressure oil in the piston side chamber 12B pushes the check valve 60 open and enters the bypass passage 57, and it is difficult for the variable throttle valve 70 to flow out from the bypass passage 57 to the rod side chamber 12A, and enters the pressure side back pressure chamber 52 from the bypass passage 57. The pressure in the pressure side back pressure chamber 52 becomes high, making it difficult for the pressure side damping valve 34 to open, and the pressure side damping force of the pressure side damping valve 34 becomes high.

(A-2) Stretch side stroke (Fig. 4 (B))
The pressure oil in the rod side chamber 12A is difficult to enter the bypass passage 57 by the variable throttle valve 70 on the closing side, the pressure in the extension side back pressure chamber 51 leading to the bypass passage 57 is lowered, and the extension side damping valve 33 is easily opened. The extension side damping force of the extension side damping valve 33 is reduced.

(B) When the variable throttle valve 70 sets the throttle degree of the bypass passage 57 to the open side
(B-1) Compression side stroke (Fig. 5 (A))
The pressure oil in the piston side chamber 12B pushes the check valve 60 open and enters the bypass passage 57, easily flows out from the bypass passage 57 through the variable throttle valve 70 on the opening side to the rod side chamber 12A, and leads to the bypass passage 57. The pressure in the pressure side back pressure chamber 52 is not increased, the pressure side damping valve 34 is easily opened, and the pressure side damping force of the pressure side damping valve 34 is reduced.

(B-2) Stretch side stroke (Fig. 5 (B))
The pressure oil in the rod side chamber 12A enters the bypass passage 57 from the variable throttle valve 70 on the opening side, does not flow out from the bypass passage 57 to the piston side chamber 12B by the check valve 60, and enters the extension side back pressure chamber 51 from the bypass passage 57. The pressure in the extension-side back pressure chamber 51 becomes high and the extension-side damping valve 33 becomes difficult to open, and the extension-side damping force of the extension-side damping valve 33 increases.

According to the present embodiment, the following operational effects can be obtained.
(a) Valve stoppers 25 and 23 are provided on the back surfaces of the damping valves 33 and 34, and backup collars 53 and 54 are provided on the valve stoppers 25 and 23 to slide through a sliding gap. The leaf springs 55 and 56 are provided, and the back springs 53 and 54 are pressed against the damping valves 33 and 34 by the leaf springs 55 and 56 to form the back pressure chambers 51 and 52, and the leaf spring 55 that presses the backup collars 53 and 54. , 56 are provided with slits 55A, 56A, and the amount of pressure leakage in the back pressure chambers 51, 52 passing through the sliding gap between the backup collars 53, 54 and the valve stoppers 25, 23 is reduced by the slits 55A, 56A of the leaf springs 55, 56. I tried to control it. The pressure in the back pressure chambers 51 and 52 is leaked from the leak passages 53B and 54B formed by the sliding gaps between the backup collars 53 and 54 and the valve stoppers 25 and 23. Can be repeated. The amount of pressure leak is stably controlled by the slits 55A and 56A of the leaf springs 55 and 56, regardless of the dimensional accuracy of the sliding gaps affected by the processing accuracy of the backup collars 53 and 54 and the valve stoppers 25 and 23. Is done. Without the need to increase the processing accuracy of the valve stoppers 25 and 23 and the backup collars 53 and 54, the amount of pressure leakage and thus the pressure in the back pressure chambers 51 and 52 are stably controlled, and the damping force characteristics of the damping valves 33 and 34 are improved. It can be kept stable.

  (b) The backup collars 53, 54 are provided with pressure receiving portions 53A, 54A for receiving the pressure of the back pressure chambers 51, 52, and the backup collars 53, 54 are pushed down by a pressure higher than a certain level. Therefore, when the pressure in the back pressure chambers 51 and 52 increases, the backup collars 53 and 54 are pushed down by the pressure acting on the pressure receiving portions 53A and 54A provided in the backup collars 53 and 54, and the backup collars 53 and 54 back up. The damping valves 33 and 34 are opened, and the upper limit (maximum damping force) of the damping force can be set.

  (c) Oil reservoirs 25A and 23A are provided on at least one of the sliding surfaces of the valve stoppers 25 and 23 and the backup collars 53 and 54. The slidability of the backup collars 53 and 54 with respect to the valve stoppers 25 and 23 can be improved.

  FIG. 6 shows a modification of the damping force adjusting device 50, in which the actuator 71 of the variable throttle valve 70 is made of a step motor, and the variable throttle valve 70 is screwed into the hollow thread portion 13A of the piston rod 13. The needle valve 70A of the variable throttle valve 70 is screwed by the motor of the actuator 71 so as to come into contact with and separate from the valve seat 57A of the bypass passage 57, and adjusts the degree of throttle with respect to the valve seat 57A. The pressure in the back pressure chamber 52 is controlled so that the extension side damping force of the extension side damping valve 33 and the compression side damping force of the compression side damping valve 34 can be adjusted.

  FIG. 7 shows a modification of the damping force adjusting device 50. A check valve 60 that allows oil to flow from the rod side chamber 12A to the bypass passage 57 is provided on the side of the bypass passage 57 that opens to the piston side chamber 12A. 70 needle valves 70A are provided on the side of the bypass passage 57 that opens to the piston side chamber 12B. The check valve housing 28, the spacer 27, the cup 26, the valve stopper 23, the piston 24, the valve stopper 25, and the spacer 22 are inserted into the piston bolt 21, and these are screwed into the piston bolt 21 by a nut 29 that is screwed onto the piston bolt 21. It is clamped and fixed between the base end step portion. Also in FIG. 7, the installation structure of the expansion side damping valve 33 and the compression side attenuation valve 34 for the expansion side flow path 31 and the pressure side flow path 32 of the piston 24, the expansion side back pressure chamber 51 for the expansion side attenuation valve 33 and the compression side attenuation valve 34. The installation structure of the compression side back pressure chamber 52, the extension side back pressure chamber 51, the backup collars 53 and 54 forming the compression side back pressure chamber 52, the installation structures of the leaf springs 55 and 56, etc. are the same as in FIGS. is there.

  In the damping force adjusting device 50 shown in FIG. 7, when the variable throttle valve 70 is provided on the side of the bypass passage 57 that opens to the piston side chamber 12B, the throttle degree of the variable throttle valve 70 is set to the closed side. In the compression side stroke, the pressure in the compression side back pressure chamber 52 is reduced and the compression side damping force is low, and in the extension side stroke, the pressure in the extension side back pressure chamber 51 is increased and the extension side damping force is increased. Adjusted. Therefore, by setting the variable throttle valve 70 in this way, when the vehicle travels on a large undulating road and the stroke of the shock absorber is the extension side stroke (high damping force state), when passing through the protrusion on the road surface, In the opposite compression side stroke, the shock absorber enters a low damping force state, and the shock absorber quickly contracts to absorb a sudden upward road surface input. Suitable for hook control).

  On the other hand, when the variable throttle valve 70 is provided on the side of the bypass passage 57 that opens to the piston-side chamber 12B, if the throttle degree of the variable throttle valve 70 is set to the open side, the pressure of the pressure-side back pressure chamber 52 in the pressure-side stroke. Is increased so that the compression-side damping force is high, and the pressure in the expansion-side back pressure chamber 51 is decreased and the expansion-side damping force is reduced in the expansion-side stroke. Therefore, by setting the variable throttle valve 70 in this way, when the vehicle travels on a large wavy road and the stroke of the shock absorber is in the compression side stroke (high damping force state), In the reverse extension stroke, the damping force is in a low damping state and the shock absorber stretches at an appropriate speed, allowing the wheel side to follow changes in the road surface, preventing sudden depression of the vehicle body, and riding comfort and driving stability. Can be secured (suitable for skyhook control).

  Although the embodiments of the present invention have been described in detail with reference to the drawings, the specific configuration of the present invention is not limited to these embodiments, and even if there is a design change or the like without departing from the gist of the present invention. It is included in the present invention. In the damping force adjusting device, the actuator of the variable throttle valve may be built in the hollow portion of the piston rod.

FIG. 1 is a sectional view showing a damping force adjusting hydraulic shock absorber that drives a variable throttle valve by a solenoid. FIG. 2 is a cross-sectional view showing the damping force adjusting structure of FIG. FIG. 3 is an enlarged view of a main part of FIG. 4A and 4B are cross-sectional views showing the compression-side stroke, and FIG. 4B is a cross-sectional view showing the expansion-side stroke in a state where the throttle degree of the variable throttle valve is set to the closed side. 5A and 5B are cross-sectional views showing the compression-side damping force and FIG. 5B is a cross-sectional view showing the expansion-side damping force in a state where the throttle degree of the variable throttle valve is set to the open side. FIG. 6 is a cross-sectional view showing a damping force adjusting hydraulic shock absorber that drives a variable throttle valve by a motor. FIG. 7 is a cross-sectional view showing a modification of the damping force adjusting hydraulic shock absorber.

Explanation of symbols

10 Hydraulic buffer 23, 25 Valve stopper 23A, 25A Oil reservoir 33, 34 Damping valve 51, 52 Back pressure chamber 53, 54 Backup collar 53A, 54A Pressure receiving portion 55, 56 Leaf spring 55A, 56A Slit

Claims (3)

In the damping force adjustment structure of the hydraulic shock absorber, the back pressure chamber is provided on the back side of the damping valve of the hydraulic shock absorber, and the damping force can be adjusted by controlling the pressure of the back pressure chamber.
A valve stopper is provided on the back of the damping valve, a backup collar that slides through the sliding gap is provided on the valve stopper, a leaf spring is provided on the back of the backup collar, and the front of the backup collar is pressed against the damping valve by the leaf spring. Forming a back pressure chamber,
Adjusting the damping force of the hydraulic shock absorber by providing a slit in the leaf spring that holds down the backup collar and controlling the amount of leakage of the pressure in the back pressure chamber that passes through the sliding gap between the backup collar and the valve stopper by the slit of the leaf spring Construction.   2. The damping force adjusting structure for a hydraulic shock absorber according to claim 1, wherein the backup collar is provided with a pressure receiving portion that receives the pressure of the back pressure chamber, and the backup collar is pushed down by a pressure equal to or higher than a predetermined pressure.   The hydraulic shock absorber damping force adjusting structure according to claim 1 or 2, wherein an oil sump is provided on at least one of the sliding surfaces of the valve stopper and the backup collar.

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