JP2001099214A - Hydraulic shock absorber - Google Patents

Abstract

(57) [Problem] To provide a hydraulic shock absorber for a front wheel, in which only a compression damping force during a brake operation is increased to prevent sinking of a front wheel side of a vehicle body and to avoid a front turning. SOLUTION: In a front wheel side hydraulic shock absorber 10, a base valve device 50 includes a normal damping valve device 60 for generating a compression side normal damping force and a high damping valve device 80 for generating a compression side high damping force in parallel. One having a shutoff device 100 that shuts off the oil passage 57A on the side of the normal damping valve device 60 during braking.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic shock absorber suitable for a front wheel of a vehicle.

[0002]

2. Description of the Related Art Conventionally, a hydraulic shock absorber of a vehicle has a piston-side oil chamber and a rod-side oil chamber defined in a cylinder by a piston supported by a piston rod inserted into the cylinder, and an oil passage connecting both oil chambers. Is formed in the piston, a damping valve is provided in the oil passage, and a damping bypass that bypasses the damping valve is provided.

However, when the vehicle is braked, the vehicle body sinks on the front wheel side and rises on the rear wheel side, causing a front turning phenomenon. Therefore, in the related art, a damping force variable device including a rotary throttle valve is provided in a damping bypass provided in each of the hydraulic shock absorbers on the front wheel side and the rear wheel side in order to prevent the vehicle body from turning forward during braking. Then, the rotary throttle valve is throttled by an electric actuator operated by a brake operation signal to generate a high damping force. The high damping force on the front wheel side prevents the vehicle body from sinking by the high damping force on the front wheel side, and the extension side on the rear wheel side. The high damping force prevents lifting of the vehicle body.

[0004]

However, in the prior art, the damping bypass of the hydraulic shock absorber is configured to generate a damping force on both the compression side and the extension side. Therefore, even if the hydraulic shock absorber on the front wheel can prevent the vehicle body from sinking due to the high damping force on the compression side during the braking operation, the damping force on the extension side also increases, resulting in hard damping characteristics. The feeling is impaired. Also, the hydraulic shock absorber on the rear wheel can prevent the body from lifting due to the high damping force on the extension side during the braking operation, but the damping force on the compression side also increases, resulting in hard damping characteristics The feeling is impaired.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a hydraulic shock absorber for a front wheel, in which only a pressure-side damping force during a brake operation is increased to prevent sinking of a front wheel of a vehicle body, thereby avoiding forward turning.

[0006]

According to a first aspect of the present invention, a piston-side oil chamber and a rod-side oil chamber are defined in a cylinder by a piston supported by a piston rod inserted into the cylinder. The piston is provided with a piston valve device with a damping valve provided in the oil passage, and the cylinder is integrated with a reservoir, and the oil passage connecting the piston side oil chamber to the reservoir oil chamber is damped. A hydraulic shock absorber comprising a base valve device provided with a valve, wherein the base valve device includes a normal damping valve device for generating a compression-side normal damping force and a high-damping valve device for generating a compression-side high damping force in parallel, the vehicle comprising: And a shutoff device for shutting off the oil passage on the side of the normal damping valve device during braking.

According to a second aspect of the present invention, in the first aspect of the present invention, each of the normal damping valve device and the high damping valve device is provided with a damping force variable device. is there.

According to a third aspect of the present invention, in the first or second aspect of the present invention, the normal damping valve device further includes a damping force variable device comprising a throttle mechanism for an oil passage by a throttle valve. It is like that.

According to a fourth aspect of the present invention, in the first or second aspect of the present invention, the high damping valve device further comprises a damping force variable device comprising an adjustment mechanism of a preset load applied to a disk valve. It is to become.

The present invention according to claim 5 provides the present invention according to claims 1-4.
In the invention according to any one of the first to third aspects, the shutoff device may further include a spool valve that is operated by hydraulic pressure of a brake device of the vehicle.

[0011]

According to the first aspect of the present invention, the following operations are provided. The base valve device of the hydraulic shock absorber is provided with a normal damping valve device and a high damping valve device that generate a compression side damping force,
During braking, the oil path on the side of the normal damping valve device was shut off.
Therefore, by using this hydraulic shock absorber on the front wheel side,
By increasing only the pressure-side damping force during the braking operation, it is possible to prevent sinking on the front wheel side of the vehicle body and to avoid turning forward.

According to the second aspect of the present invention, the following operations are provided. Since the damping force variable device is provided in each of the normal damping valve device and the high damping valve device, both the damping force of the compression side normal damping force during normal use and the compression side high damping force during braking can be adjusted independently of each other.

According to the third aspect of the invention, the following operation is provided. Usually, the damping valve device adjusts the damping force by a throttle mechanism of an oil passage by a throttle valve, so that the damping force at a low speed can be adjusted.

According to the fourth aspect of the invention, the following operations are provided. Since the damping force is adjusted by the adjustment mechanism of the preset load applied to the disc valve by the high damping valve device, the initial operation at the time of braking is suppressed by the disc valve, and the sinking on the front wheel side of the vehicle body can be effectively prevented. .

According to the fifth aspect of the present invention, the following operations are provided. The spool valve that is activated by the hydraulic pressure of the brake device shuts off the oil passage on the normal damping valve device side during braking, and can be made lighter than an electric actuator.
Sensors and a control unit (ECU) are not required, and operation can be performed without delay.

[0016]

FIG. 1 is a schematic diagram showing a front wheel side hydraulic shock absorber, FIG. 2 is a schematic diagram showing an upper half of FIG. 1, FIG. 3 is a schematic diagram showing a lower half of FIG. FIG. 5 is a sectional view taken along the line IV-IV in FIG. 3, FIG. 5 is a schematic view showing a rear wheel side hydraulic shock absorber, and FIG.
FIG. 7 is a schematic diagram showing the upper half of FIG. 5, and FIG. 7 is a schematic diagram showing the lower half of FIG.

The present embodiment relates to a dive prevention device used for a four-wheeled vehicle. This dive prevention device is provided between the left and right front wheels and the vehicle body by one left and right front wheel side hydraulic shock absorber 10 (FIGS. 1 to 1).
4) and one left and right rear wheel-side hydraulic shock absorber 110 (FIGS. 5 to 7) between the left and right rear wheels and the vehicle body. The pressure-side high damping force generated in the side hydraulic shock absorber 10 prevents sinking on the front wheel side of the vehicle body, and the extension-side high damping force generated in the rear wheel side hydraulic shock absorber 110 prevents floating on the rear wheel side of the vehicle body. And avoid turning in front of the vehicle. Hereinafter, each of the front wheel side hydraulic shock absorber 10 and the rear wheel side hydraulic shock absorber 110 will be described in detail.

(Front-wheel-side hydraulic shock absorber 10) (FIGS. 1 to 4) As shown in FIGS. 1 to 4, the front-wheel-side hydraulic shock absorber 10 has a hollow piston rod 12 inserted into a cylinder 11, and a cylinder 11 and a piston. Suspension spring 1 on the outside of rod 12
3 are interposed.

The cylinder 11 has a wheel-side mounting portion 14,
The piston rod 12 is provided with a vehicle body side mounting portion 15. A spring support adjusting ring 16 and a spring support 17 are screwed around the outer periphery of the cylinder 11, and the spring support 1 is mounted on the piston rod 12.
8 is fixed, a suspension spring 13 is interposed between the spring support 17 and the spring support 18, and the spring support adjustment ring 1
The set length of the suspension spring 13 can be adjusted by the screwing of the spring support 6 and the spring receiver 17. The elastic force of the suspension spring 13 absorbs the impact force that the vehicle receives from the road surface.

The cylinder 11 has a rod guide 21 through which the piston rod 12 passes. The rod guide 21
The piston rod 12 is mounted on the cylinder 11 via an O-ring 22 in a liquid-tight manner, and the piston rod 12 is slidable in a liquid-tight manner on an inner diameter portion provided with an oil seal 23, a bush 24, and a dust seal 25. The cylinder 11 is provided with a compression side bumper 26 outside the rod guide 21, and at the time of maximum compression, the compression side bumper 26 abuts against a bump rubber 27 provided in the piston rod 12 so as to regulate the maximum compression stroke. Further, the cylinder 11 includes an extension-side bump rubber 28 inside the rod guide 21.

The hydraulic shock absorber 10 includes the piston valve device 3
0 and a base valve device 50. The hydraulic shock absorber 10 is configured such that the damping force generated by the piston valve device 30 and the base valve device 50 causes the suspension spring 13 to absorb the impact force of the cylinder 11 and the piston rod 1.
2 is suppressed.

(Piston Valve Device 30) (FIGS. 1 and 2) The piston valve device 30 is integrated by screwing a piston bolt 12A having a valve stopper 31 to an end of a piston rod 12 inserted into the cylinder 11. Then, a compression-side damping valve 32 (disc valve), a piston 33, an extension-side damping valve 34 (disc valve), and a valve stopper 35 are mounted on the piston bolt 12A, and these are fixed with nuts 36.

The piston 33 slidably contacts the inside of the cylinder 11 in a liquid-tight manner via an O-ring 37A and a piston ring 37B provided on the outer peripheral portion, and the inside of the cylinder 11 communicates with a piston-side oil chamber 38A in which the piston rod 12 is not accommodated. , And a rod-side oil chamber 38B in which the piston rod 12 is housed. The piston 33 includes a compression-side damping valve 32 and a compression-side flow path 39 that enables communication between the piston-side oil chamber 38A and the rod-side oil chamber 38B. An extension-side flow path 40 that allows communication with the oil chamber 38B is provided. Compression damping valve 32
And the distance Ra from the center of support (same as the center of the piston 33) to the center of the flow path of the compression side flow path 39,
The distance Rb from the support center (same as the center of the piston 33) to the center of the flow path of the extension side flow path 40 is set to Ra> Rb, and the extension side damping based on the bending deformation of the extension side damping valve 34. The force is set to be larger than the compression-side damping force based on the bending deformation of the compression-side damping valve 32.

In the piston valve device 30, a damping force adjusting rod 42 operated by an adjuster device 41 is passed through a hollow portion of the piston rod 12 so as to be able to advance and retreat, and a needle valve 43 (throttle valve) at the tip of the adjusting rod 42. As a result, the piston-side oil chamber 3 provided in the piston rod 12
The opening area of the bypass flow path 44 between the rod 8A and the rod-side oil chamber 38B is adjustable.

The bypass passage 44 of the piston rod 12
Can be opened at the end face of the nut 36 into the piston side oil chamber 38A.
6. Extension side sub damping valve (slightly slow damping valve composed of a disc valve) attached by valve stopper 47
8, which can be opened and closed.

Therefore, when the hydraulic shock absorber 10 is compressed, the oil in the piston side oil chamber 38A passes through the pressure side flow path 39, opens the pressure side damping valve 32, and is guided to the rod side oil chamber 38B.

When the hydraulic shock absorber 10 is extended, when the relative speed between the cylinder 11 and the piston rod 12 is low, the oil in the rod-side oil chamber 38B flows through the bypass passage 44 having the needle valve 43 and the sub damping valve 48. The flow then flows to the piston-side oil chamber 38 </ b> A, and the expansion-side damping force is generated by the bending deformation of the sub damping valve 48 and the throttle resistance by the needle valve 43 during this time. This damping force is adjusted by rotating the adjuster device 41.

When the relative speed between the cylinder 11 and the piston rod 12 is medium to high when the hydraulic shock absorber 10 is extended, the oil in the rod-side oil chamber 38B passes through the extension-side flow path 40 and operates the extension-side damping valve 34. Deflected and deformed piston oil chamber 38A
To produce a damping force on the extension side.

(Base valve device 50) (FIGS. 1, 3,
FIG. 4) In the base valve device 50, a case 51 is screwed to the cylinder 11, and a reservoir 52 is screwed to the case 51. In the reservoir 52, the oil chamber 55A is partitioned from the pressurized gas chamber 55B by a diaphragm 54 (a free piston may be used), and the cap 53 is provided with a gas sealing valve 56. Base valve device 5
0 is the piston-side oil chamber 38 in the oil chamber 55A of the reservoir 52.
The oil path 57 connecting A is divided into two, a normal damping valve device 60 for generating a compression side normal damping force is interposed in one oil path 57A, and a high damping for generating a compression side high damping force in the other oil path 57B. The valve device 80 is interposed, and the normal damping valve device 60 and the high damping valve device 80 are provided in parallel. The base valve device 50 includes a shutoff device 100 that shuts off the oil passage 57A of the normal damping valve device 60 when the vehicle is braked. Hereinafter, the normal damping valve device 60, the high damping valve device 80, and the shutoff device 100 will be described.

(A) Normal damping valve device 60 (FIG. 3) In the normal damping valve device 60, a cap 62 to which a piston bolt 61 is screwed is fixed to the case 51 by screwing. 63, a compression-side damping valve 64 (disc valve), a piston 65, an extension-side check valve 66 (disc valve), and a valve stopper 67 are mounted, and these are fixed by a nut 68. The piston 65 is connected to the oil passage 57A by the O-ring 65A provided on the outer peripheral portion and the oil chamber 55A to the piston side oil chamber 38A.
A partition is provided on the A side, and a compression-side flow path 69 including a compression-side damping valve 64 and an expansion-side flow path 70 including an expansion-side check valve 66 are provided.

In the normal damping valve device 60, a damping force adjusting rod 72 operated by an adjuster device 71 (variable damping force device) is passed through the hollow portion of the piston bolt 61 so as to be able to advance and retreat. The needle valve 73 (throttle valve) at the tip makes it possible to restrict the opening area of the bypass flow path 74 between the piston-side oil chamber 38A and the oil chamber 55A provided in the piston bolt 61.

Therefore, in the normal damping valve device 60, when the hydraulic shock absorber 10 is compressed, the oil corresponding to the volume of the piston rod 12 that has entered the cylinder 11 flows from the piston side oil chamber 38A to the oil passage 57A (69, 74). Is discharged to the oil chamber 55 </ b> A of the reservoir 52. At this time, when the relative speed between the cylinder 11 and the piston rod 12 is low, the compression side damping force is obtained by the throttle resistance of the needle valve 73 provided in the bypass passage 74. This damping force is adjusted by adjusting the position of the needle valve 73 by the adjuster device 71. When the relative speed between the cylinder 11 and the piston rod 12 is medium to high, the oil passing through the flow passage 69 from the piston side oil chamber 38A is supplied to the pressure side normal damping valve 6.
4 is flexibly deformed and guided to the oil chamber 55A of the reservoir 52 to generate a pressure-side damping force.

When the hydraulic shock absorber 10 is extended, the cylinder 1
The oil corresponding to the withdrawal volume of the piston rod 12 withdrawing from 1 is transferred from the oil chamber 55A of the reservoir 52 to the piston-side oil chamber 38A through the extension-side check valve 66 and the oil passage 57A.

(B) High damping valve device 80 (FIG. 4) In the high damping valve device 80, a cap 82 to which a piston bolt 81 is screwed is screwed and fixed to the case 51,
A valve stopper 83, a compression-side damping valve 84 (disc valve), a piston 85, an extension-side check valve 86, and a valve stopper 87 are mounted on the piston bolt 81, and these are fixed with a nut 88. The piston 85 divides the oil passage 57B into a piston oil chamber 38A side and an oil chamber 55A side by an O-ring 85A provided on the outer peripheral portion, and a compression-side flow path 89 having a compression-side damping valve 84 and an expansion-side check valve 86. And the extension side flow path 90 provided.

In the high damping valve device 80, a damping force adjusting rod 92 operated by an adjuster device 91 (variable damping force device) is passed through the hollow portion of the piston bolt 81 so as to be able to advance and retreat. A spring 94 is supported by an abutting spring retainer 93, and the spring force of the spring 94 is transmitted via a disk retainer 95 to the above-described compression side damping valve 84.
In addition, the preset load applied to the compression side damping valve 84 can be adjusted.

Therefore, in the high damping valve device 80,
When the hydraulic shock absorber 10 is compressed, oil corresponding to the volume of the piston rod 12 that has entered the cylinder 11 is discharged from the piston-side oil chamber 38A to the oil chamber 55A of the reservoir 52 through the oil passage 57B (the pressure-side passage 89). Is done. At this time, the oil passing through the compression-side flow path 89 causes the compression-side damping valve 84 to bend and be guided to the oil chamber 55A of the reservoir 52, and generates a compression-side high damping force applied with a preset load by the spring 94.

When the hydraulic shock absorber 10 is extended, the cylinder 1
The oil corresponding to the withdrawal volume of the piston rod 12 withdrawing from 1 is transferred from the oil chamber 55A of the reservoir 52 to the piston-side oil chamber 38A through the extension-side check valve 86 and the oil passage 57B.

(C) Shut-off Device 100 (FIG. 3) In the shut-off device 100, a valve holder 101 is interposed in an intermediate portion of an oil passage 57A in which a normal damping valve device 60 is interposed in a case 51. Accommodates a spool valve 102 and a return spring 103, and is provided with a cap 104 screwed to the case 51.
1 is fixed. A push rod 105 is inserted through the cap 104. The shut-off device 100 pushes the spool valve 102 from a standby position against a spring force of a return spring 103 by a push rod 105 operated by hydraulic pressure of a brake device of the vehicle.
The second outer circumferential groove 102A is switched from the conductive position to the oil passage 57A to the non-conductive position, and as a result, the oil passage 57A on the side of the normal damping valve device 60 is shut off.

Accordingly, the front-wheel-side hydraulic shock absorber 10 performs a damping action as follows. (Compression) When the hydraulic shock absorber 10 is compressed, (a) the normal damping valve 60 of the base valve device 50 is provided in the bypass flow passage 74 whose opening is adjusted by the needle valve 73 or the flow passage 69 of the piston 65. Compression side damping valve 6
4 generates a compression damping force due to the oil passing therethrough, and (b) the piston valve device 30 generates a compression damping force due to the oil passing through the compression damping valve 32 provided in the compression passage 39 of the piston 33. At the time of this compression, the compression side damping valve 84 of the high damping valve device 80 depends on the magnitude of the preset load applied to the compression side damping valve 84 of the high damping valve device 80 and the high speed of the relative speed between the cylinder 11 and the piston rod 12. There is also the possibility of obtaining a compression damping force by the oil that opens and passes through it.

(At the time of extension) When the hydraulic shock absorber 10 is extended,
In the piston valve device 30, the bypass passage 4 of the piston rod 12 whose opening is adjusted by the needle valve 43.
4 through the extension side sub damping valve 48 or the extension side valve 34 provided in the extension side flow path 40 of the piston 33.
The oil passing through the pipe generates an extension damping force.

(During braking) When the driver steps on the brake pedal of the vehicle, the hydraulic pressure of the brake device operates the spool valve 102 via the push rod 105 of the shut-off device 100, and the oil passage on the side of the normal damping valve device 60. Cut off 57A. For this reason, in the base valve device 50, the normal damping valve device 60 is inoperative during the compression operation of the hydraulic shock absorber 10, so that the oil corresponding to the volume of the piston rod 12 that has entered the cylinder 11 enters the piston side oil chamber 38 </ b> A. Through the oil passage 57B, through the pressure damping valve 84 of the high damping valve device 80 provided in the oil passage 57B, and discharged to the oil chamber 55A of the reservoir 52. As a result, the oil passes through the pressure damping valve 84. A high damping force on the pressure side due to oil is generated.

When the hydraulic shock absorber 10 is fully compressed, the bumper 26 on the cylinder 11 side and the bump rubber 27 on the piston rod 12 abut against each other to perform a buffering operation at the time of maximum compression. When the hydraulic shock absorber 10 is fully extended, the bump rubber 28 on the side of the cylinder 11 and the valve stopper 31 on the side of the piston rod 12 abut against each other to perform a buffering action at the time of extension.

Therefore, the hydraulic shock absorber 10 on the front wheel side has the following operation. The base valve device 50 of the hydraulic shock absorber 10 is provided with a normal damping valve device 60 and a high damping valve device 80 for generating a compression side damping force.
Side oil passage 57A was shut off. Therefore, this hydraulic shock absorber 1
By using 0 on the front wheel side, only the pressure side damping force during the brake operation is increased, the sinking of the front wheel side of the vehicle body can be prevented, and the front turning can be avoided.

Since the damping force variable devices (adjuster device 71 and adjuster device 91) are provided in each of the normal damping valve device 60 and the high damping valve device 80, the compression side normal damping force during normal use and the compression side high damping force during braking are provided. Can be adjusted independently of each other.

Normally, the damping valve device 60 is
Since the damping force is adjusted by the throttle mechanism of the bypass flow path 74 by 3, the damping force at low speed can be adjusted.

The damping force is adjusted by a preset load adjusting mechanism (adjuster device 91) applied by the high damping valve device 80 to the compression side damping valve 84 (disc valve). It is possible to effectively prevent sinking on the front wheel side of the vehicle body.

The oil passage 57A on the side of the normal damping valve device 60 is shut off by the spool valve 102 operated by the hydraulic pressure of the brake device during braking, and can be made lighter than the electric actuator.
CU) is unnecessary, and the operation can be performed without delay.

(Rear Wheel Side Hydraulic Shock Absorber 110) (FIGS. 5 to 7) The rear wheel side hydraulic shock absorber 110 has a hollow piston rod 112 inserted into a cylinder 111 as shown in FIGS. A suspension spring 113 is interposed on the outside of the piston rod 112.

The cylinder 111 has a wheel-side mounting portion 114, and the piston rod 112 has a vehicle-body-side mounting portion 115. A spring receiving adjusting ring 116 and a spring receiving 117 are screwed around the outer periphery of the piston rod 112,
1 has a spring receiver 118 fixed thereto.
A suspension spring 113 is interposed between the spring support 7 and the spring receiver 118, and the set length of the suspension spring 113 can be adjusted by screwing the spring receiver adjusting ring 116 and the spring receiver 117. The elastic force of the suspension spring 113 absorbs the impact force that the vehicle receives from the road surface.

The cylinder 111 has a rod guide 121 through which a piston rod 112 passes. Rod guide 1
Reference numeral 21 is mounted on the cylinder 111 in a liquid-tight manner via an O-ring 122, and allows the piston rod 112 to slide in a liquid-tight manner on the inner diameter portion provided with the oil seal 123, the bush 124, and the dust seal 125. The cylinder 111 is provided on the outer side of the rod guide 121.
8, the bump rubber 126 is provided, and at the time of maximum compression, the bump rubber 126 is abutted against the bump stopper 127 provided in the piston rod 112 so that the maximum compression stroke can be regulated. Further, the cylinder 111 includes the rod guide 1.
An extension-side bump rubber 128 is provided inside 21.

The hydraulic shock absorber 110 has a piston valve device 130 and a base valve device 180. The hydraulic shock absorber 110 suppresses the expansion and contraction vibration of the cylinder 111 and the piston rod 112 due to the absorption of the impact force by the suspension spring 113 by the damping force generated by the piston valve device 130 and the base valve device 180.

(Piston Valve Device 130) (FIGS. 5 and 6) The piston valve device 130 is provided with a valve stopper 13 at the end of a piston rod 112 inserted into a cylinder 111.
1 is screwed into and integrated with the piston bolt 112A.
32 (disc valve), piston 133, extension side damping valve 134 (disc valve), valve stopper 135
Are attached, and these are fixed with nuts 136.

The piston 133 slidably contacts the inside of the cylinder 111 in a liquid-tight manner via an O-ring 137A and a piston ring 137B provided on the outer peripheral portion, and the inside of the cylinder 111 is moved into the piston-side oil chamber 1 in which the piston rod 112 is not accommodated.
38A and a rod-side oil chamber 138B in which the piston rod 112 is stored. The piston 133 includes a compression-side damping valve 132 and enables a communication between the piston-side oil chamber 138A and the rod-side oil chamber 138B.
And a piston-side oil chamber 13 including an extension-side damping valve 134.
An extension-side flow path 140 that allows communication between the rod-side oil chamber 138B and the rod-side oil chamber 138B. The distance Ra from the support center of the compression-side damping valve 132 (same as the center of the piston 133) to the center of the compression-side flow path 139, and the extension center flow from the support center of the expansion-side damping valve 134 (same as the center of the piston 133). Road 1
The distance Rb to the center of the flow path 40 is set to Ra> Rb, and the extension damping force based on the bending deformation of the extension damping valve 134 is smaller than the compression damping force based on the bending deformation of the compression damping valve 132. It is set to be larger.

The piston valve device 130 includes a bypass 201 for high damping that generates a high damping force on the extension side and a bypass 202 for normal damping that generates a normal damping force on the expansion side. It is provided in a detour. The normal damping bypass 202 includes a shutoff device 203 that shuts off the bypass 202 when the vehicle is braked. Hereinafter, the bypass 201 for high attenuation, the bypass 202 for normal attenuation, and the shutoff device 203 will be described.

(High Damping Bypass 201) (FIG. 6) The high damping bypass 201 is provided on the piston 133 side, and the damping force adjusting rod 142 operated by the adjuster device 141 (damping force variable device) is connected to the piston rod. 1
12 through the hollow portion 12 so as to be able to advance and retreat.
The opening area of the bypass flow path 144 between the piston-side oil chamber 138A and the rod-side oil chamber 138B provided in the piston rod 112 is adjusted by the needle valve 143 (throttle valve) at the tip of the piston rod 112 to adjust the extension-side damping force. It is possible.

In the high attenuation bypass 201,
The bypass flow passage 144 of the piston rod 112 can be opened at the end face of the nut 136 into the piston side oil chamber 138A, and the nut 136 is provided with a fastening bolt 145 and a small nut 14.
6. The extension side sub damping valve attached by the valve stopper 147 (a very low speed damping valve composed of a disc valve)
148 can be opened and closed.

(Normal Damping Bypass 202) (FIGS. 6 and 7) In the normal damping bypass 202, holes 151 are formed at a plurality of circumferential positions at the uppermost end of the cylinder 111 on the side of the rod-side oil chamber 138B. Cover 1 covering the periphery of the hole 151
O-rings 153, 154
Through the stopper ring 155 and the set screw 15
It is fixed at 6. The cover 152 forms a ring-shaped oil passage 157 around the cylinder 111.

On the other hand, a case 161 is screwed to the lower end of the cylinder 111, and a reservoir 162 is screwed to the case 161. The reservoir 162 has an oil chamber 165A partitioned from a pressurized gas chamber 165B by a diaphragm 164 (a free piston may be used), and the cap 163 is provided with a gas sealing valve 166.

A communication pipe 167 is interposed between the cover 152 and the case 161 outside the cylinder 111, and the cover 152, the communication pipe 167 and the case 161 connect the rod-side oil chamber 138B to the cover 152. Ring-shaped oil passage 1
57, the bypass passage 1 communicating with the oil chamber 165A.
68 are formed.

Normally, the bypass 202 for damping is
On the side of 11, a damping force adjusting rod 172 operated by an adjuster device 171 (variable damping force device) is passed through the cover 152 so as to be able to advance and retreat, and a needle valve 173 (throttle valve) at the tip of the adjusting rod 172 causes the cover 152 to move.
The opening area of the bypass flow path 168 between the rod-side oil chamber 138B and the oil chamber 165A is adjusted by adjusting the throttle so that the extension-side damping force can be adjusted.

The bypass passage 1 of the high attenuation bypass 201
The extension side damping force generated at 44 is the normal damping bypass 202
The damping force is set to be higher than the extension-side damping force generated in the bypass flow path 168 of FIG.

Therefore, when the rear wheel hydraulic shock absorber 110 is compressed, the oil in the piston side oil chamber 138A passes through the pressure side flow path 139 and opens the pressure side damping valve 132 to open the rod side oil chamber 138.
It is led to B.

When the rear wheel side oil chamber shock absorber 110 is extended, when the relative speed between the cylinder 111 and the piston rod 112 is low, the oil in the rod side oil chamber 138B flows through the normal damping bypass 202 having the needle valve 173. The reservoir 16 passes through the bypass passage 168 and / or the bypass passage 144 of the high attenuation bypass 201 having the needle valve 143.
The oil flows into the second oil chamber 165A and the piston-side oil chamber 138A, and a throttling resistance by the needle valves 173 and 143 therebetween generates an extension-side damping force. This damping force is adjusted by rotating the adjuster devices 141 and 171.

Further, when the relative speed between the cylinder 111 and the piston rod 112 is medium or high when the rear wheel hydraulic shock absorber 110 is extended, the oil in the rod side oil chamber 138B passes through the extension side flow path 140 and the extension side damping. The valve 134 is bent and guided to the piston-side oil chamber 138A to generate an extension-side damping force.

(Shutoff Device 203) (FIG. 7) The shutoff device 203 is provided with a valve holder 175 in the middle of the bypass passage 168 in the case 161, and accommodates a spool valve 176 in the valve holder 175. Valve holder 1 with screwed cap 177
75 is fixed. A push rod 178 is inserted through the cap 177. The shut-off device 203 is provided in the valve holder 175 by pushing the spool valve 176 from a standby position by pushing a spool valve 176 against a spring force of a return spring (not shown) by a push rod 178 operated by hydraulic pressure of a brake device of the vehicle. Bypass channel 168
Cut off.

(Base Valve Device 180) (FIG. 7) In the base valve device 180, a cap 182 to which a piston bolt 181 is screwed is provided at a portion of the case 161 where a bypass passage 168 of the normal attenuation bypass 202 is formed. Screwed and fixed, piston bolt 181
, A valve stopper 183, a compression side damping valve 184 (disc valve), a piston 185, an extension side check valve 186 (disc valve), and a valve stopper 187 are attached, and these are fixed by a nut 188. The piston 185 connects the bypass passage 168 of the normal damping bypass 202 with the O-ring 185A to the piston side oil chamber 138A.
And a compression-side flow path 189 provided with a compression-side damping valve 184 and an expansion-side flow path 190 provided with an expansion-side check valve 186.

In the base valve device 180, a damping force adjusting rod 192 operated by an adjuster device 191 (variable damping force device) is passed through a hollow portion of the piston bolt 181 so as to be able to advance and retreat. The piston bolt 181 is controlled by the valve 193 (throttle valve).
, The bypass passage 1 between the piston oil chamber 138A and the bypass passage 168 and the reservoir 162.
The aperture area of the aperture 94 is adjustable.

In the base valve device 180, when the hydraulic shock absorber 110 is compressed, the oil corresponding to the volume of the piston rod 112 that has entered the cylinder 111 flows from the piston side oil chamber 138A through the bypass passages 194, 168 to the reservoir 162. To the oil chamber 165A. At this time,
When the relative speed between the cylinder 111 and the piston rod 112 is low, the compression side damping force is obtained by the throttle resistance of the needle valve 193 provided in the bypass passage 194.
This damping force is adjusted by adjusting the position of the needle valve 193 by the adjuster device 191. Also, cylinder 1
When the relative speed between the piston rod 11 and the piston rod 112 is medium to high, the oil passing through the flow path 189 from the piston side oil chamber 138A bends and deforms the pressure side damping valve 184, and the reservoir 16
The oil is guided to the second oil chamber 165A to generate a pressure-side damping force.

When the hydraulic shock absorber 110 is extended, oil corresponding to the withdrawal volume of the piston rod 112 withdrawing from the cylinder 111 flows from the oil chamber 165A of the reservoir 162 through the extension-side check valve 186 and the flow path 190 to the piston-side oil chamber. 1
38A.

Therefore, the rear wheel hydraulic shock absorber 110 performs a damping action as follows. (Compression) When the hydraulic shock absorber 110 is compressed, (a) in the base valve device 180, the bypass passage 194 whose opening is adjusted by the needle valve 193 or the piston 18
5 generates a pressure-side damping force due to the oil passing through the pressure-side damping valve 184 provided in the flow path 189 of the fifth valve 189, and (b) the oil passing through the pressure-side damping valve 132 provided in the pressure-side flow path 139 of the piston 133 in the piston valve device 130. A compression damping force is generated.

(At the time of extension) When the hydraulic shock absorber 110 is extended, (a) when the relative speed between the cylinder 111 and the piston rod 112 is low, the opening is adjusted by the needle valve 173 of the normal damping bypass 202 in the piston valve device 130. (B) When the vehicle is running at medium speed, the normal damping bypass 202 is generated.
And oil flows into both the high attenuation bypass 201 and the above (a).
And a bypass flow path 144 whose opening is adjusted by the needle valve 143 of the high-attenuation bypass 201 generates an extension-side damping force.
(c) At high speed, the bypass 2 for high attenuation described in (a) and (b) above
01. The extension damping force generated by the normal damping bypass 202 and the oil passing through the extension damping valve 134 provided in the extension flow path 140 of the piston 133 are generated.
The extension-side damping force at low speed and middle speed is adjusted by the degree of throttle of the needle valve 173 of the normal attenuation bypass 202 and the needle valve 143 of the high attenuation bypass 201.

(During braking) When the driver steps on the brake pedal of the vehicle, the hydraulic pressure of the brake device operates the spool valve 176 via the push rod 178 of the shut-off device 203, and the bypass flow on the side of the normal damping bypass 202 is controlled. Block road 168. Therefore, the piston valve device 13
At 0, the normal damping bypass 202 does not operate during the extension operation of the hydraulic shock absorber 110, so that the cylinder 111
The oil corresponding to the retreat volume of the piston rod 112 retreating from the piston-side oil chamber 138 </ b> B passes through the bypass passage 144 of the high-attenuation bypass 201, passes through the needle valve 143 provided in the bypass passage 144, and receives the piston-side oil. Room 13
8A, and as a result, a high-pressure-side damping force is generated by passing through the bypass passage 144.

When the hydraulic shock absorber 110 is most compressed, the bump rubber 126 on the cylinder 111 side and the bump stopper 127 on the piston rod 112 abut against each other to perform a buffering operation during the most compression. When the hydraulic shock absorber 110 is fully extended, the bump rubber 12 on the side of the cylinder 111 is closed.
8 and valve stopper 131 on the side of piston rod 112
And acts as a buffering action at the time of extension.

Therefore, the hydraulic shock absorber 110 on the rear wheel side has the following operation. A bypass 202 for normal damping and a bypass 201 for high damping, which generate a damping force on the expanding side, are bypassed to extend the flow path 140 of the piston valve device 130 of the hydraulic shock absorber 110, and the bypass 202 for normal damping is shut off during braking. . Therefore, by using the hydraulic shock absorber 110 on the rear wheel side, it is possible to increase only the extension-side damping force during the brake operation, and to avoid front turning in which the floating of the rear wheel side of the vehicle body is prevented.

Since the normal damping bypass 202 provided with the shutoff device 203 is provided on the cylinder 111 side, the installation of the shutoff device 203 and the operation route of the shutoff device 203 are simplified.

Since the normal damping bypass 202 adjusts the damping force by the throttle mechanism of the bypass passage 168 by the needle valve 173, the damping force at low speed can be adjusted.

Since the sub damping valve 148 (disk valve) and the needle valve 143 are provided in series with the high damping bypass 201, the initial operation at the time of braking is suppressed by the disk valve, and the lifting of the rear wheel side of the vehicle body is effectively prevented. it can.

The bypass passage 168 of the normal damping bypass 202 is shut off by a spool valve 176 which is operated by the hydraulic pressure of the brake device, and can be made lighter than an electric actuator without using a sensor and a control unit (ECU) during braking. And can be operated reliably without delay.

The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration of the present invention is not limited to this embodiment, and the design can be changed without departing from the scope of the present invention. The present invention is also included in the present invention.

[0080]

As described above, according to the present invention, in the front-wheel-side hydraulic shock absorber, only the compression-side damping force during the braking operation is increased, and the sinking of the front wheel side of the vehicle body can be prevented to prevent the front turning. .

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a front wheel side hydraulic shock absorber;

FIG. 2 is a schematic diagram showing an upper half of FIG. 1;

FIG. 3 is a schematic diagram showing a lower half of FIG. 1;

FIG. 4 is a sectional view taken along the line IV-IV in FIG. 3;

FIG. 5 is a schematic view showing a rear wheel side hydraulic shock absorber;

FIG. 6 is a schematic diagram showing the upper half of FIG. 5;

FIG. 7 is a schematic diagram showing a lower half of FIG. 5;

[Explanation of symbols]

 Reference Signs List 10 hydraulic shock absorber 11 cylinder 12 piston rod 30 piston valve device 32 compression-side damping valve 33 piston 34 extension-side damping valve 38A piston-side oil chamber 38B rod-side oil chamber 39, 40 flow path (oil passage) 50 base valve device 52 reservoir 55A Oil chambers 57, 57A, 57B Oil passage 60 Normal damping valve device 71 Adjuster device (variable damping force device) 73 Needle valve (throttle valve) 80 High damping valve device 84 Pressure damping valve (disk valve) 91 Adjuster device (variable damping force) Device) 100 shut-off device 102 spool valve

Claims (5)

[Claims] A piston supported by a piston rod inserted into a cylinder defines a piston-side oil chamber and a rod-side oil chamber in the cylinder, and an oil passage connecting the two oil chambers is formed in the piston. A hydraulic shock absorber comprising a piston valve device provided with a damping valve in the cylinder, a reservoir integrated into a cylinder, and a base valve device provided with a damping valve in an oil passage connecting a piston side oil chamber to an oil chamber of the reservoir. Wherein the base valve device includes a normal damping valve device for generating a compression-side normal damping force and a high damping valve device for generating a compression-side high damping force in parallel, and shuts off an oil passage on the normal damping valve device side when the vehicle is braked. A hydraulic shock absorber having a shutoff device. 2. A variable damping device is provided for each of the normal damping valve device and the high damping valve device.
The described hydraulic shock absorber. 3. The hydraulic shock absorber according to claim 1, wherein said normal damping valve device is provided with a damping force variable device comprising a throttle mechanism for an oil passage by a throttle valve. 4. The hydraulic shock absorber according to claim 1, wherein said high damping valve device is provided with a damping force variable device comprising a mechanism for adjusting a preset load applied to a disc valve. 5. The system according to claim 1, wherein the shutoff device comprises a spool valve which is operated by hydraulic pressure of a brake device of the vehicle.
5. The hydraulic shock absorber according to any one of 4.