JP2001280399A - Hydraulic shock absorber - Google Patents

Abstract

(57) [Summary] To provide a hydraulic shock absorber capable of generating a damping force depending on a stroke amount. SOLUTION: In a front fork 10, a stopper 70 is provided on an upper outer periphery of a damper cylinder 21 and a float 71 is provided below the stopper 70. The float 71 comes into contact with the stopper 70 in a process of raising the oil level when contracted. A throttle passage 72 for the operating oil in the oil chamber 31 is formed between the outer periphery of the float 71 and the inner periphery of the vehicle body side tube 11 or the wheel side tube 12.

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 use in a motorcycle front fork or the like.

[0002]

2. Description of the Related Art Conventionally, as a front fork,
As described in JP-A-6-173995, a vehicle body side tube and a wheel side tube are slidably fitted, a damper cylinder is erected on the vehicle body side tube, a piston rod is erected on the wheel side tube, and the piston rod is erected. Is inserted into the damper cylinder while being supported by a rod guide provided in the opening of the damper cylinder, and an oil chamber is formed in a lower portion between the vehicle body side tube and the wheel side tube, and a gas chamber is formed in the upper portion, and the damper cylinder is formed. In some cases, a suspension spring is interposed between a spring receiving member fixed to the outer periphery of the vehicle and a wheel-side tube.

In this prior art, an oil chamber between a vehicle body side tube and a wheel side tube is vertically divided by a spring receiving member, and a throttle passage connecting the upper and lower oil chambers to the spring receiving member is provided. Thereby, when the front fork is compressed, the flow of the hydraulic oil accompanying the rise of the oil level in the oil chamber is restricted by the above-described restriction passage, and a compression-side damping force is generated.

[0004]

A throttle passage for hydraulic oil in an oil chamber between a vehicle body side tube and a wheel side tube is fixedly provided on a spring receiving member. For this reason,
The damping force generation characteristic of the throttle passage depends on the speed regardless of the stroke, whether it is a large stroke such as when landing after a jump or a small stroke such as when passing a short protrusion on the road surface. For this reason, when a high speed acts on the front fork when passing through the short protrusion during high-speed running, a high damping force is generated, and high acceleration is transmitted from the steering wheel to the rider's hand, resulting in a hard evaluation.

Therefore, conventionally, there has been a demand for a damping force generator that generates a low damping force during a small stroke and generates a high damping force during a large stroke, depending on the stroke amount.

An object of the present invention is to make it possible to generate a damping force depending on a stroke amount in a hydraulic shock absorber.

[0007]

According to a first aspect of the present invention, a vehicle body side tube and a wheel side tube are slidably fitted to each other, a damper cylinder is erected on the vehicle body side tube, and a piston is mounted on the wheel side tube. The rod is erected, and the piston rod is inserted into the damper cylinder while being supported by a rod guide provided at the opening of the damper cylinder.An oil chamber is provided at a lower portion between the vehicle body side tube and the wheel side tube, and a gas is provided at the upper portion. In a hydraulic shock absorber formed with a chamber, a stopper is provided on the upper outer periphery of the damper cylinder, and below the stopper on the outer periphery of the damper cylinder, in the axial direction of the damper cylinder in conjunction with the rise in the oil level of the oil chamber. A movable float is provided, and the float comes into contact with the stopper in the process of raising the oil level when the body side tube and the wheel side tube are contracted, and the outer periphery of the float and the body side tube or the wheel Between the inner circumference of the tube, in which so as to form a throttle passage for the hydraulic fluid of the oil chamber.

According to a second aspect of the present invention, in the first aspect of the present invention, the stopper is formed in an annular shape, and the float is formed in a cylindrical shape. , The inner circumference of the float is fitted to the outer circumference of the stopper via a minute gap.

The invention described in claim 3 is the first or second invention.
And a coil spring is provided between the float and the stopper.

According to a fourth aspect of the present invention, there is provided the check valve according to any one of the first to third aspects, wherein the float is capable of releasing a negative pressure on an inner peripheral side to the oil chamber. It is provided with.

[0011]

According to the first aspect of the present invention, the following operations are provided. During a small stroke, such as when passing a short protrusion on a road surface, the float does not come into contact with the stopper, so that a throttle passage is not formed. At the time of a large stroke such as at the time of landing after jumping, the float comes into contact with the stopper to form a throttle passage and generate a damping force. Therefore, it is possible to generate a compression damping force that depends on the stroke amount.

According to the second aspect of the invention, the following operations are provided. Since the float is formed in a cylindrical shape, the above-described throttle passage formed by the outer periphery of the float is used as a choke passage, and linear linear proportional attenuation characteristics can be obtained.

When the tube on the vehicle body side and the tube on the wheel side are contracted, the inner periphery of the float is fitted to the outer periphery of the stopper via a small gap to form a dash pot, so that the impact when the float comes into contact with the stopper is reduced. it can.

According to the third aspect of the invention, the following effects are obtained. When the vehicle body side tube and the wheel side tube shrink, the impact when the float comes into contact with the stopper can be reduced by the coil spring.

When the vehicle body side tube and the wheel side tube are reversed from the contracted state to the extended side, the coil spring presses the float so as to separate it from the stopper, and quickly returns the float to the initial position as the oil level lowers. To

By setting the spring characteristics of the coil spring, the moving speed of the float can be controlled, and the timing of generation of the damping force by the float can be adjusted.

According to the fourth aspect of the invention, the following operations are provided. When the body side tube and the wheel side tube reverse from the contracted state to the extended side, the negative pressure generated between the stopper and the inner circumference of the float is released by the check valve, and the float moves to the initial position as the oil level goes down. To return quickly.

[0018]

1 is an overall sectional view showing a front fork, FIG. 2 is an enlarged sectional view of a lower part of FIG. 1, FIG. 3 is an enlarged sectional view of an intermediate part of FIG. 1, and FIG. 4 is an enlarged sectional view of an upper part of FIG. FIG. 5
FIG. 6 is a schematic diagram in which main parts of FIG. 1 are modified, and FIG. 6 is a schematic diagram in which main parts of FIG. 1 are modified.

The front fork 10 (hydraulic shock absorber)
As shown in FIGS. 1 to 4, a wheel-side tube (inner tube) 12 is slidably inserted into a vehicle-body-side tube (outer tube) 11, and a suspension spring 13 is interposed between the tubes 11 and 12. At the same time, the single cylinder type damper 14 is installed upside down.

A bush 15 to which the outer peripheral portion of the wheel side tube 12 slides is fitted on the inner peripheral portion of the lower end of the vehicle body side tube 11, and the inner peripheral portion of the vehicle body side tube 11 is fitted on the outer peripheral portion of the upper end of the wheel side tube 12. A bush 16 that is in sliding contact is fitted.

The tube 11 on the vehicle body side is the upper bracket 1
The wheel-side tube 12 is supported on the vehicle body side via the lower bracket 17A and the lower bracket 17B, and is connected to the axle via the axle bracket 18.

A cap 19 is screwed to the upper end of the body side tube 11 via an O-ring in a liquid-tight manner.
The upper end of the damper cylinder 21 (upper cylinder tube 21A) of the damper 14 is screwed to the. An oil lock collar 23 is fitted on the inner periphery of the lower end portion of the wheel side tube 12 in a liquid-tight manner via an O-ring, and the oil lock collar 23 is fixed to the axle bracket 18 with the bottom bolt 24 in a liquid-tight manner via the O-ring. I have. Also, bottom bolt 2
4 is a piston rod (hollow rod) 22 of the damper 14.
The base end of the piston rod 22 is screwed and locked by a lock nut 24A, and the distal end of the piston rod 22 is inserted into the damper cylinder 21. The piston rod 22 is supported by a bush 25A of a rod guide 25 screwed into a lower end opening of the damper cylinder 21 (the lower cylinder tube 21B), and is inserted into the damper cylinder 21. An oil lock collar 26 is provided on the outer periphery of the rod guide 25. A rebound spring 27 is supported on the inner end surface of the rod guide 25.

The suspension spring 13 has a spring receiver 28 mounted on the outer peripheral surface of the base end of the oil lock collar 23.
And the damper cylinder 21 (lower cylinder tube 21B)
And a spring receiver 29 fixed using a stopper ring 30 on the outer peripheral surface of the intermediate portion of the second member. Also,
An oil chamber 31 and a gas chamber 32 are provided inside the vehicle body side tube 11 and the wheel side tube 12, and the gas confined in the gas chamber 32 constitutes a gas spring. The resilient forces of the suspension spring 13 and the gas spring absorb the impact force that the vehicle receives from the road surface. The oil level of the oil chamber 31 moves up and down due to the expansion and contraction of the body side tube 11 and the wheel side tube 12 of the front fork 10. In FIG. 1, LA is the oil level at maximum extension, and LB is the oil level at maximum compression. It is. The spring receiver 29 is provided with a large opening flow path 29A so that the hydraulic oil can freely flow up and down inside the oil chamber 31.

The damper 14 has a piston valve device (extension-side damping force generator) 40 and a base valve device (compression-side damping force generator) 50. The damper 14 suppresses the expansion and contraction vibration of the vehicle body side tube 11 and the wheel side tube 12 due to the absorption of the impact force by the suspension spring 13 and the gas spring by the damping force generated by the piston valve device 40 and the base valve device 50.

The damper cylinder 21 of the damper 14 is
For assembling the base valve device 50 into the damper cylinder 21, the upper and lower two cylinder tubes 21A,
1B is divided into two parts, and these are joined together. A lock nut 32 is screwed into a connection between the upper cylinder tube 21A and the lower cylinder tube 21B.

Hereinafter, the damping mechanism of the front fork 10 will be described. (Piston valve device 40) Piston valve device 40
The piston holder 41 is attached to the tip of the piston rod 22.
And a piston 42 is mounted on the piston holder 41. The piston 42 slidably contacts the inside of the damper cylinder 21 (the lower cylinder tube 21B), and the inside of the damper cylinder 21 communicates with a piston-side oil chamber 43A in which the piston rod 22 is not accommodated and a rod-side oil chamber 43B in which the piston rod 22 is accommodated. Partition into The piston 42 includes an expansion-side valve 44A, and is provided with an expansion-side flow path 44 that enables communication between the piston-side oil chamber 43A and the rod-side oil chamber 43B, and a compression-side valve (check valve) 45A. And a pressure side flow passage 45 that allows communication between the pressure side flow passage 45 and the rod side oil chamber 43B.

In the piston valve device 40, the damping force adjusting rod 47 connected to the adjuster 46 passes through the hollow portion of the piston rod 22, and the piston holder 4 is moved by the needle 47A at the tip of the damping force adjusting rod 47.
1, a piston-side oil chamber 43A and a rod-side oil chamber 4
The flow path area of the bypass 48 with the 3B can be adjusted.

Therefore, when the front fork 10 is compressed, the oil in the piston-side oil chamber 43A passes through the pressure-side flow path 45, opens the pressure-side valve 45A, and is guided to the rod-side oil chamber 43B.

When the front fork 10 is extended, when the relative speed between the damper cylinder 21 and the piston rod 22 is low, the oil in the rod-side oil chamber 43B
The piston side oil chamber 43 through the bypass path 48 having the 7A
A, and the expansion side damping force is generated by the throttle resistance of the needle 47A during this time. This damping force is adjusted by adjusting the position of the needle 47A by the adjuster 46.

When the front fork 10 is extended,
When the relative speed between the damper cylinder 21 and the piston rod 22 is medium to high, the oil in the rod-side oil chamber 43B
Deflects the expansion side valve 44A and is guided to the piston side oil chamber 43A to generate an expansion side damping force.

(Base Valve Device 50) In the base valve device 50, a guide pipe 51 is screwed to the above-mentioned cap 19 screwed to the upper end portion of the upper cylinder tube 21A, and a housing holder is attached to the tip of the guide pipe 51. 51
A into the housing holder 51A.
The valve housing 52 is held by B or the like. The upper part of the guide pipe 51 is formed with a small diameter 51C. The valve housing 52 is in liquid-tight contact with the inner periphery of the upper cylinder tube 21A, and defines a base valve chamber 53 above the piston-side oil chamber 43A. The valve housing 52 includes a pressure side valve 54A and includes a piston side oil chamber 43.
A-side flow path 5 that enables communication between A and the base valve chamber 53
4 and a piston-side oil chamber 43A having an extension-side valve 55A.
Flow path 55 that allows communication between the base valve chamber 53 and
And Further, the housing holder 51A includes a bypass flow path 56 that allows the piston side oil chamber 43A and the base valve chamber 53 to communicate with each other by bypassing the pressure side flow path 54 and the expansion side flow path 55.

The damping force adjusting rod 58 screwed to the cap 19 has an adjuster 59 and is inserted into the guide pipe 51 so that the flow path area of the bypass flow path 56 can be adjusted by the needle 58A at the tip.

The base valve device 50 is provided inside the upper cylinder tube 21A.
A free piston type partition wall member 61 that slides in a liquid-tight manner along the A and the guide pipe 51 via an O-ring is provided. The partition member 61 is connected to the oil chamber 5 communicating with the piston side oil chamber 43A on the valve housing 52 side of the base valve chamber 53.
3A and the gas chamber 53B on the cap 19 side (the gas chamber 32).
And communication). An oil seal 64 is provided on the inner periphery of the partition member 61 so as to be in liquid-slidable contact with the outer periphery of the guide pipe 51.
Is provided. The spring 62 is interposed between the partition wall member 61 and the cap 19 so as to have a slight initial load at the time of the maximum extension.

The piston rod 2 is installed in the damper cylinder 21.
At the time of compression where 2 enters, this spring 62 contracts,
The oil chamber in the damper cylinder 21 is pressurized by the amount of the spring load of the spring 62 at this time, thereby preventing the occurrence of cavitation in the oil chamber in the damper cylinder at the time of extension and the generation of damping force at the time of compression following the extension. Avoid delays.

Therefore, when the front fork 10 is compressed, the piston rod 22 that has entered the damper cylinder 21
Is discharged from the piston side oil chamber 43A to the oil chamber 53A of the base valve chamber 53 through the bypass flow path 56 or the pressure side flow path 54 of the valve housing 52. At this time, when the relative speed between the damper cylinder 21 and the piston rod 22 is low, the pressure-side damping force is obtained by the throttle resistance of the needle 58A provided in the bypass passage 56. This damping force is adjusted by adjusting the position of the needle 58A by the adjuster 59. Also, when the relative speed between the damper cylinder 21 and the piston rod 22 is medium to high, the piston side oil chamber 43A
The oil that passes through the pressure valve 54A bends and deforms the pressure side valve 54A and is guided to the oil chamber 53A of the base valve chamber 53 to generate a pressure side damping force.

When the front fork 10 extends, oil corresponding to the retreat volume of the piston rod 22 retreating from the damper cylinder 21 flows from the oil chamber 53A of the base valve chamber 53 through the extension side flow path 55 of the valve housing 52 to the piston side. The oil is returned to the oil chamber 43A.

Each time the piston rod 22 of the front fork 10 makes a stroke, the base valve device 50 opens the oil chamber 31 attached to the outer peripheral surface of the piston rod 22.
In order to carry the oil into the damper cylinder 21, a passage 63 for returning the oil to the oil chamber 31 is provided. That is, the passage 63 has a small gap 63A formed between the oil seal 64 on the inner periphery of the partition member 61 and the small diameter portion 51C formed on the upper part of the guide pipe 51, and the hole 63B formed on the upper part of the upper cylinder. Formed from

Accordingly, the front fork 10 performs a damping action as follows. (Compression) When the front fork 10 is compressed, the base valve device 50 generates a compression damping force due to oil flowing through the needle 58A of the valve housing 52 or the compression valve 54A, and the piston valve device 40 hardly generates a damping force.

(Extension) When the front fork 10 is extended, the piston 42
The oil flowing through the needle 47A or the expansion valve 44A generates an expansion damping force, and the base valve device 50 hardly generates a damping force.

Due to these damping forces on the compression side and the extension side, the expansion and contraction vibration of the front fork 10 is suppressed.

When the front fork 10 is fully compressed, the oil lock collar 26 at the lower end of the lower cylinder tube 21B of the damper cylinder 21 is moved to the wheel side tube 1
2 is fitted to an oil lock collar 23 provided at the lower end, and the oil compressed between the two causes an oil lock effect to prevent the damper 20 from bottoming out.

When the front fork 10 is fully extended, the piston holder 4
The lower end surface of the rod 1 abuts against a rebound spring 27 supported by a rod guide 25 provided at the opening of the damper cylinder 21 to perform a buffering action for extension.

However, the front fork 10 is provided with the following configuration in order to impart the stroke (position) dependency to the above-described damping characteristics during compression. That is, the lock nut 32 screwed to the upper outer periphery of the damper cylinder 21, in this embodiment, the connection between the upper and lower cylinder tubes 21 </ b> A and 21 </ b> B is used as the stopper 70. On the other hand, a stopper 7 is provided around the outer periphery of the damper cylinder 21 (the lower cylinder tube 21B).
0, the vehicle body side tube 11 and the wheel side tube 12
A lightweight float 71 made of resin or the like, which moves in the axial direction of the damper cylinder 21 in conjunction with the rise in the oil level of the oil chamber 31 during this time, is provided. That is, the float 71 is supported by the upper end surface of the spring receiver 29 in a stationary state, but moves up and down in conjunction with a change in the oil level of the oil chamber 31 due to expansion and contraction of the front fork 10. The float 71 comes into contact with the stopper 70 as shown by a two-dot chain line in FIG. 3 during the process of raising the oil level when the front fork 10 contracts, and the outer periphery of the float 71 and the inside of the wheel-side tube 12 (inner tube). A throttle passage 72 that allows the hydraulic oil in the oil chamber 31 to flow upward is formed between the oil passage 31 and the periphery.

At this time, the stopper 70 has an annular shape. The float 71 has a cylindrical shape and the damper cylinder 21
And a hollow forming portion 71B that can receive the stopper 70 above the base 71A.
Thereby, when the stopper 70 enters the hollow forming portion 71B of the float 71 when the front fork 10 is contracted, the inner periphery of the hollow forming portion 71B of the float 71 fits into the outer periphery of the stopper 70 via a minute gap. Thus, a dashpot is formed by the stopper 70 and the float 71.

Therefore, according to the present embodiment, the following operations are provided. At the time of a small stroke such as when passing a short protrusion on a road surface, the float 71 does not come into contact with the stopper 70, so that the throttle passage 72 is not formed. At the time of a large stroke, such as at the time of landing after jumping, the float 71 contacts the stopper 70 to form the throttle passage 72 and generate a damping force. Therefore, it is possible to generate a compression damping force that depends on the stroke amount.

Since the float 71 is formed in a cylindrical shape,
The above-described throttle passage 72 formed by the outer periphery of the float 71 is used as a choke passage, so that linear linear proportional attenuation characteristics can be obtained.

Body side tube 11 and wheel side tube 1
When the float 2 is contracted, the inner circumference of the float 71 is fitted to the outer circumference of the stopper 70 via a minute gap to form a dash pot, so that the impact when the float 71 contacts the stopper 70 can be reduced.

Hereinafter, a modified example of the front fork 10 will be described. (A) As shown in FIG. 5, the hollow forming portion 71B of the float 71
The lower end of the coil spring 73 is attached to the upper end surface of the coil spring 73 so that the upper end of the coil spring 73 abuts on the lower end surface of the stopper 70 while the float 71 and the stopper 70 approach each other (see FIG. 5B )).

Therefore, according to this configuration, the following operations are provided. When the vehicle body side tube 11 and the wheel side tube 12 are contracted, the impact when the float 71 contacts the stopper 70 can be reduced by the coil spring 73.

Body side tube 11 and wheel side tube 1
When 2 is reversed from the contracted state to the extended side, the coil spring 73 presses the float 71 so as to be separated from the stopper 70, and quickly returns the float 71 to the initial position as the oil level lowers.

By setting the spring characteristics of the coil spring 73, the moving speed of the float 71 can be controlled, and the timing at which the float 71 generates a damping force can be adjusted.

(B) As shown in FIG. 6, a base 71A of the float 71 is provided with a check valve 81 and a passage 82 for discharging a negative pressure on the inner peripheral side to the oil chamber 31 side. 83 is a stopper ring for regulating the opening stroke of the check valve 81.

Therefore, according to this configuration, the following operations are provided. When the vehicle body side tube 11 and the wheel side tube 12 are reversed from the contracted state to the extended side, the negative pressure generated between the inner periphery of the float 71 and the stopper 70 is eliminated by the check valve 81, and the lowering of the oil level is caused. Quick return of the float 71 to the initial position.

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. For example, in the present invention, the vehicle body side tube may be an inner tube and the wheel side tube may be an outer tube, in which case, the float forms a throttle passage between the body side tube and the inner tube. Becomes

[0055]

As described above, according to the present invention, it is possible to generate a damping force depending on a stroke amount in a hydraulic shock absorber.

[Brief description of the drawings]

FIG. 1 is an overall sectional view showing a front fork.

FIG. 2 is a lower enlarged sectional view of FIG. 1;

FIG. 3 is an enlarged sectional view of an intermediate portion of FIG. 1;

FIG. 4 is an enlarged cross-sectional view of the upper part of FIG.

FIG. 5 is a schematic diagram in which main parts of FIG. 1 are modified.

FIG. 6 is a schematic diagram in which main parts of FIG. 1 are modified.

[Explanation of symbols]

 Reference Signs List 10 front fork (hydraulic shock absorber) 11 body side tube 12 wheel side tube 21 damper cylinder 22 piston rod 25 rod guide 31 oil chamber 32 gas chamber 70 stopper 71 float 72 throttle passage 73 coil spring 81 check valve

Claims (4)

[Claims] 1. A vehicle body side tube and a wheel side tube are slidably fitted to each other, a damper cylinder is erected on the vehicle body side tube, a piston rod is erected on the wheel side tube, and the piston rod is opened by opening the damper cylinder. Inserted into the damper cylinder while being supported by the rod guide provided in the part, an oil chamber is provided in the lower part between the body side tube and the wheel side tube,
In a hydraulic shock absorber having a gas chamber formed in an upper part, a stopper is provided on an outer periphery of an upper part of a damper cylinder, and a lower part of the damper cylinder is provided on an outer periphery of the damper cylinder in conjunction with a rise in the oil level of the oil chamber. A float that moves in the axial direction is provided, and the float comes into contact with the stopper in the process of raising the oil level when the body-side tube and the wheel-side tube shrink, and the outer periphery of the float and the inner circumference of the body-side tube or the wheel-side tube Between,
A hydraulic shock absorber, wherein a throttle passage for operating oil in the oil chamber is formed. 2. The stopper is formed in an annular shape, and the float is formed in a cylindrical shape. When the vehicle body side tube and the wheel side tube are contracted, the inner periphery of the float is fitted to the outer periphery of the stopper via a minute gap. The hydraulic shock absorber according to claim 1, wherein 3. The hydraulic shock absorber according to claim 1, wherein a coil spring is provided between the float and the stopper. 4. The float according to claim 1, further comprising a check valve capable of releasing a negative pressure on an inner peripheral side of the float to the oil chamber.
The hydraulic shock absorber according to any one of claims 1 to 3.