JP2003278815A - Hydraulic shock absorber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To display excessive damping function in both left and right steering directions and simultaneously lessen difference between both left and right steering performances in a hydraulic shock absorber composed of a steering damper. <P>SOLUTION: In the hydraulic shock absorber 10, the absorber is provided with an annular oil chamber 51 being normally into communication with one of the oil chamber 31 providing in the damper 11, within shifting range of a free piston 60 between an outer periphery of the free piston 60 and an inner periphery of a sub-tank 40, and fixes a first bulkhead member 44 in other side of an oil chamber 50 in a sub-tank 40. Further, the absorber 10 is provided with a second bulkhead 63 sliding and fitting with the first bulkhead 44 in tip of the free piston 60. It is configured to hermetically partition the oil chambers 52, 53 into respective inner and outer peripheral sides of the second bulkhead 63, and to normally communicate the oil chamber 53 on the outer peripheral side of the second bulkhead 63 to other of the oil chamber 32 provided in the damper 11. It is further configured to normally communicate the oil chamber 52 on the inner peripheral side via an oil passage 64 provided in the free piston 60 to the annular oil chamber 51. <P>COPYRIGHT: (C)2004,JPO

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 steering damper of a motorcycle or the like.

[0002]

2. Description of the Related Art Conventionally, in a motorcycle or the like, a steering damper is interposed between a vehicle body and a steering wheel. The steering damper absorbs shake in the steering direction of the steering wheel, which is caused by disturbance such as kickback that the tire receives from the road surface.

In a conventional steering damper, a piston that slides in a damper body is provided with a piston rod that penetrates both ends of the damper body and extends to the outside, and the oil chambers on both sides of the piston in the damper body are provided in the damper body. A free piston, which communicates with an oil chamber in a sub tank attached to the main body and is back-supported by a spring, is provided at one end of the oil chamber in the sub tank.

The free piston provided in the steering damper pressurizes the oil chamber in the damper body to prevent cavitation of the working oil, and compensates for volume change due to the temperature of the working oil to prevent damage to the seal portion. It contributes to prevent damage to the seal by avoiding a sudden pressure rise in the damper body by absorbing excessive input.

[0005]

However, in the prior art, the free piston pressurizes only one oil chamber in the damper main body, and has the following problems.

The excessive input absorbing action is only exerted only when an excessive input is exerted in one of the left and right steering directions in which one oil chamber in the damper body is excessively boosted.

The spring load of the spring for urging the free piston is set so that the free piston does not move during normal operation of the handle. However, in actuality, even during normal operation, the free piston may be displaced by one of the left and right steering forces that pressurizes one of the oil chambers in the damper body. In this case, a feeling of loss of steering force on one of the left and right sides is generated, and a difference occurs in steering performance between the left and right sides.

An object of the present invention is, in a hydraulic shock absorber constituting a steering damper, to exert an excessive input absorbing action in both the left and right steering directions and to reduce the left and right steering performance difference.

[0009]

According to a first aspect of the present invention, a piston that slides in a damper body is provided with a piston rod that penetrates both ends of the damper body and extends to the outside. A hydraulic shock absorber in which each oil chamber communicates with an oil chamber in a sub tank attached to the damper body, and a free piston back-supported by a spring is provided at one end side of the oil chamber in the sub tank. Between the outer circumference of the sub-tank and the inner circumference of the sub-tank, an annular oil chamber that is in constant communication with one of the oil chambers provided in the damper main body is provided within the moving range of the free piston. A first partition wall member is fixed to the other end side of the second partition wall, and a second partition wall portion slidably fitted to the first partition wall member is provided at the tip of the free piston. Of the peripheral side and the outer peripheral side Sealed partition the oil chamber to respectively, the second
The oil chamber on the outer peripheral side of the partition wall is always in communication with the other oil chamber provided in the damper body, and the oil chamber on the inner peripheral side is connected to the annular chamber via the oil chamber provided in the free piston. It is in constant communication with the oil chamber.

According to a second aspect of the invention, in addition to the first aspect of the invention, the pressure receiving areas of the oil chamber on the outer peripheral side and the oil chamber on the inner peripheral side of the free piston are formed to be substantially the same.

According to a third aspect of the present invention, in the invention according to any one of the first to third aspects, the first partition wall member further communicates with the orifice oil for communicating the oil chamber on the outer peripheral side and the oil chamber on the inner peripheral side. A passage is provided, and a damping valve operated from the outside of the sub-tank faces the orifice oil passage.

According to a fourth aspect of the invention, in the invention according to any one of the first to fourth aspects, the damper body is composed of an inner cylinder and an outer cylinder, and the sub-tank is connected to the damper body to be integrally formed. A partition part that partitions the two oil chambers is provided at an axially intermediate part between the inner cylinder and the outer cylinder, and the piston that slides in the inner cylinder through the oil chambers on both sides of the partition part. One of the oil chambers on both sides communicates with the oil chamber on the inner peripheral side of the second partition wall provided in the sub-tank, and the other of the oil chambers on both sides of the piston connects the oil on the outer peripheral side of the second partition wall. It communicates with the room.

[0013]

FIG. 1 is a sectional view showing a hydraulic shock absorber,
FIG. 2 is an enlarged view of a main part of FIG. The hydraulic shock absorber 10 constitutes a steering damper of a motorcycle or the like. The hydraulic shock absorber 10 includes a piston 12 sliding on the inside of the damper body 11, a piston rod 15 extending through the rod guides 13 and 14 provided at both ends of the damper body 11 and extending to the outside.
Is provided. In the hydraulic shock absorber 10, the damper main body 11 is composed of an inner cylinder 16 and an outer cylinder 17, and a rod guide 13 having an O-ring 13A on one end side of the outer cylinder 17 and an oil seal 18 are liquid-tightly fitted, The rod guide 13 is attached to the inner cylinder 16 by the cap 19 screwed to the outer cylinder 17 and the O-ring 1
3B is liquid-tightly fitted to hold the backup, and at the other end of the outer cylinder 17, a rod guide 14 having an O-ring 14A and an oil seal 21 are liquid-tightly fitted and screwed to the outer cylinder 17. The attached cap 22 liquid-tightly fits the rod guide 14 to the inner cylinder 16 via the O-ring 14B to hold it as a backup, and as a result, the inner cylinder 16, the rod guides 13, 14 and the oil are retained by the two caps 19, 22. The seals 18 and 21 are fixed to the outer cylinder 17.

In the hydraulic shock absorber 10, a vehicle body side connecting portion 23 for connecting the damper main body 11 to the vehicle body is provided on an outer side portion of the outer cylinder 17, and a handle side connecting portion 24 for connecting the piston rod 15 to the left and right one end sides of the handle. Is provided at one end of the piston rod 15.

In the hydraulic shock absorber 10, the oil chambers 31 and 32 on both sides of the piston 12 in the damper body 11 communicate with the oil chamber 50 in the sub tank 40 attached to the damper body 11. In the hydraulic shock absorber 10, a free piston 60 biased by a spring 41 is slidably provided on one end side of an oil chamber 50 in the sub tank 40. The spring 41 is supported by a cap 43 supported by a stopper ring 42 at one end side opening of the sub tank 40. The spring 41 may be an air spring of an air chamber.

In the hydraulic shock absorber 10, large diameter portions 61 and 62 provided at one end and an intermediate portion of the free piston 60 are liquid-tightly inserted into the sub tank 40 via O-rings 61A and 62A, respectively. Between the outer circumference of the free piston 60 sandwiched between the large diameter portion 62 and the inner circumference of the sub tank 40, within the movement range of the free piston 60, the damper main body 11 is provided via the communication passage 31A provided in the damper main body 11. There is provided an annular oil chamber 51 which is in constant communication with one of the oil chambers 31 provided in.

In the hydraulic shock absorber 10, the first partition member 44 is screwed and fixed to the other end side of the oil chamber 50 in the sub tank 40, and the first partition member 44 and the first partition member 44 are provided at the tip of the free piston 60. A small-diameter second partition wall portion 63 that is slidably fitted in a liquid-tight manner via an O-ring 63A is provided. The side oil chamber 53 is sealed and partitioned.

The oil chamber 52 on the inner peripheral side of the second partition wall 63 is always communicated with the annular oil chamber 51 through an oil passage 64 provided in the free piston 60, and by extension, one oil chamber of the damper body 11 is provided. Always in communication with 31.

The oil chamber 53 on the outer peripheral side of the second partition 63 is provided with the communication passage 32A provided in the damper body 11 and the sub tank 4.
Annular gap 45 between the inner circumference of 0 and the outer circumference of the first partition member 44.
Through the oil chamber 32 of the damper main body 11 at all times.

Therefore, in the hydraulic shock absorber 10, one oil chamber 31 in the damper main body 11 has the free piston 60.
Of the free piston 60 and the inner peripheral side oil chamber 52 provided in the second partition 63 of the free piston 60 are always communicated with each other. The pressure receiving surfaces on the large diameter portion 61 side and the small diameter portion 62 side of the annular oil chamber 51 of the free piston 60, which face each other, are provided on both axial sides of the annular oil chamber 51 and cancel each other out. Therefore, the free piston 60 pressurizes the one oil chamber 31 in the damper body 11 via the pressure receiving surface of the inner peripheral side oil chamber 52.

On the other hand, the other oil chamber 3 in the damper body 11
2 always communicates with the outer peripheral side oil chamber 53 provided in the second partition 63 of the free piston 60. Therefore, the free piston 60 pressurizes the other oil chamber 32 in the damper main body 11 via the pressure receiving surface of the outer peripheral side oil chamber 53.

As a result, the free piston 60 pressurizes both the oil chambers 31 and 32 in the damper body 11.

Here, in the hydraulic shock absorber 10, the pressure receiving areas of the inner peripheral side oil chamber 52 and the outer peripheral side oil chamber 53 of the free piston 60 are formed to be substantially the same.

The hydraulic shock absorber 10 also has a damping force adjusting device 70. The damping force adjusting device 70 includes the sub tank 40.
The first partition member 44 provided in the above is provided with an orifice oil passage 71 that communicates the oil chamber 52 on the inner circumference side and the oil chamber 53 on the outer circumference side of the free piston 60, and a needle-like damping valve 72 operated from the outside of the sub tank 40. Facing the orifice oil passage 71. The damping valve 72 is screwed with respect to the first partition member 44 by the rotation operation applied to the adjuster 73, adjusts the opening degree of the orifice oil passage 71, and the working oil passing through the orifice oil passage 71 is changed to the orifice oil passage. It exerts a passage resistance depending on the opening of 71. The adjuster 73 is additionally provided with a click stop mechanism portion 74 composed of a ball and a spring so that the opening degree of the orifice oil passage 71 can be adjusted stepwise.

Further, the hydraulic shock absorber 10 includes a sub tank 40.
Are continuously formed on the damper body 11 and are integrally formed. Then, a partition portion 35 that partitions the two oil chambers 33 and 34 is provided in the outer cylinder 17 at an axially intermediate portion between the inner cylinder 16 and the outer cylinder 17. 35A is an O-ring. One oil chamber 31 of the piston 12 sliding on the inner cylinder 16 of the damper body 11 is provided with an oil passage 33A of the inner cylinder 16, an oil chamber 33, and an oil passage 33B of the outer cylinder 17.
And the inner peripheral side oil chamber 52 of the second partition wall 63 provided in the sub-tank 40 via the annular oil chamber 51. In addition, the other oil chamber 32 of the piston 12 that slides in the inner cylinder 16 of the damper body 11 includes an oil passage 34A of the inner cylinder 16, an oil chamber 34, and an oil passage 34B of the outer cylinder 17.
And the above-mentioned communication passage 32 </ b> A, which is composed of the above, and the annular space 45, and communicates with the outer peripheral side oil chamber 53 of the second partition wall 63 provided in the sub tank 40.

Therefore, the hydraulic shock absorber 10 operates as follows. (A) Normal handle operation When the handle is operated, the piston rod 15 slides left and right slowly. When the piston rod 15 slides to the left in FIGS. 1 and 2, the working oil in the oil chamber 31 in the damper body 11 flows from the communication passage 31A into the oil chamber 50 in the sub tank 40.
Through the orifice oil passage 71 of the damping force adjusting device 70 and from the communication passage 32A to the oil chamber 32 in the damper body 11.
And the damping force generated by the damping force adjusting device 70 during this period is applied to the handle operating force.

When the piston rod 15 slides to the right in FIGS. 1 and 2, the working oil in the oil chamber 32 in the damper body 11 passes from the communication passage 32A through the orifice oil passage 71 of the damping force adjusting device 70, It is transferred to the oil chamber 31 of the damper main body 11 from the communication passage 31A via the oil chamber 50 in the sub tank 40, and the damping force generated by the damping force adjusting device 70 in the meantime is applied to the handle operating force.

The free piston 60 is set to be immovable by the spring load of the spring 41.

(B) Absorption of disturbance from the road surface Due to disturbance such as kickback that the tire receives from the road surface,
When the steering wheel tries to swing in the steering direction, the piston rod 15 rapidly slides left and right. At this time, the operating oil in the oil chamber 31 or the oil chamber 32 in the damper body 11 is
Although it tries to pass through the orifice oil passage 71 of the damping force adjusting device 70 in the same route as (A), the passage resistance of the orifice oil passage 71 is large because the flow velocity of the oil passing through the orifice oil passage 71 is high. The orifice oil passage 71 tries to prevent the passage of this oil. As a result, the shake of the steering wheel is locked and the disturbance is absorbed.

(C) When the steering wheel receives an excessive impact force in the steering direction due to a collision of the excessive input tire with the curb, the oil chamber 31 or the oil chamber 32 in the damper main body 11 is excessively pressurized. At this time,
The hydraulic oil in the oil chamber 31 whose pressure is increased in the damper main body 11 reaches the oil chamber 50 (annular oil chamber 51, inner peripheral side oil chamber 52) in the sub-tank 40 through the same path as the above (A), and the free piston 6
Displace 0 to absorb this excessive impact force. In addition, the hydraulic oil in the oil chamber 32 whose pressure is increased in the damper body 11 is as described above.
It extends to the oil chamber 50 (outer peripheral side oil chamber 53) in the sub tank 40 through the same route as (A), and in this case also, the free piston 60
Is displaced to absorb this excessive impact force.

According to this embodiment, there are the following effects. (Operation corresponding to claim 1) Since the free piston 60 pressurizes both oil chambers 31 and 32 in the damper body 11, the following (a) and (b) can be realized.

(A) One oil chamber 31 in the damper body 11
Is excessively increased, the tire collides with the curb during an excessive input that acts in one of the left and right steering directions and also when the other oil chamber 32 is excessively increased in the left and right steering directions that cause an excessive input. The excessive input of is absorbed to prevent a sudden increase in pressure in the damper body 11 and prevent damage to the seal portion.

(B) When the steering wheel is operated normally, the free piston 60 responds to both left and right steering forces almost equally.
Is no longer displaced, and the left-right steering performance difference can be reduced.

(Operation corresponding to claim 2) The pressure receiving area of the inner peripheral side oil chamber 52 of the free piston 60, which pressurizes one oil chamber 31 in the damper body 11, and the other oil chamber in the damper body 11. The pressure receiving areas of the outer peripheral side oil chamber 53 of the free piston 60 that pressurize 32 are formed to be substantially the same. Therefore, the free piston 60 responds equally to both the left and right steering forces, eliminates the steering performance difference between the left and right, and makes it possible to provide the same steering feel for the left and right handles.

(Operation corresponding to claim 3) Since the damping force adjusting device 70 is provided so as to be operable from the outside of the sub tank 40, the structure of the damping force adjusting device 70 can be simplified and the damping force can be adjusted easily.

(Operation corresponding to claim 4) Each of the oil chambers 31 and 32 in the damper body 11 has an oil chamber 33 on both sides of a partition 35 provided between the inner cylinder 16 and the outer cylinder 17, respectively. Sub tank 4 through each of 34
The inner peripheral side oil chamber 52 and the outer peripheral side oil chamber 53 provided in the second partition wall portion 63 of the free piston 60 inside 0 are communicated with each other. Therefore, while shortening the total length of the sub tank 40, the inner peripheral side oil chamber 52 and the outer peripheral side oil chamber 5 in the sub tank 40 are
Both of the oil chambers 3 in the damper body 11
The sub tank 40 and the hydraulic shock absorber 10 can be downsized by communicating with each other.

Although the embodiment of the present invention has been described in detail with reference to the drawings, the specific configuration of the present invention is not limited to this embodiment, and the design can be changed without departing from the gist of the present invention. Etc. are included in the present invention.

[0038]

As described above, according to the present invention, in the hydraulic shock absorber constituting the steering damper, it is possible to exert an excessive input absorbing action in both the left and right steering directions and reduce the difference in the left and right steering performances. it can.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a hydraulic shock absorber.

FIG. 2 is an enlarged view of a main part of FIG.

[Explanation of symbols] 10 hydraulic shock absorber 11 damper body 12 pistons 15 Piston rod 16 inner cylinder 17 outer cylinder 31, 32 oil chamber 33, 34 Oil chamber 35 partition 40 sub tank 41 spring 44 First Partition Member 50 oil chamber 51 annular oil chamber 52 Inner peripheral oil chamber 53 Peripheral oil chamber 60 free pistons 63 Second partition wall 70 Damping force adjustment device 71 Orifice oil passage 72 damping valve

Claims (4)

[Claims] 1. A piston that slides in a damper body,
Piston rods that penetrate both ends of the damper body and extend to the outside are provided, and the oil chambers on both sides of the piston in the damper body communicate with the oil chambers in the sub-tank attached to the damper body. A hydraulic shock absorber provided with a free piston back-supported by a spring on one end side of the inside of the damper main body between the outer circumference of the free piston and the inner circumference of the sub tank within the movement range of the free piston. An annular oil chamber that is in constant communication with one of the oil chambers provided in the sub tank, the first partition member is fixed to the other end side of the oil chamber in the sub tank, and the first piston is attached to the tip of the free piston. A second partition wall portion that is slidably fitted with the partition wall member is provided, and oil chambers are sealed and partitioned on the inner peripheral side and the outer peripheral side of the second partition wall portion, respectively. Chamber inside the damper body Always communicates with the digits other oil chamber, the oil chamber of the inner circumference side, via an oil chamber provided in said free piston, a hydraulic shock absorber, characterized in that it always communicates with the oil chamber of the annular. 2. The hydraulic shock absorber according to claim 1, wherein the pressure receiving areas of the oil chamber on the outer peripheral side and the oil chamber on the inner peripheral side of the free piston are formed to be substantially the same. 3. The first partition member is provided with an orifice oil passage that communicates the oil chamber on the outer peripheral side with the oil chamber on the inner peripheral side, and the damping oil operated from the outside of the sub tank is provided in the orifice oil passage. The hydraulic shock absorber according to any one of claims 1 to 3, which faces a valve. 4. The damper main body is composed of an inner cylinder and an outer cylinder, the sub-tank is connected to the damper main body and integrally formed, and two oils are provided in an axially intermediate portion between the inner cylinder and the outer cylinder. A second partition part in which a partition part for partitioning the chamber is provided, and one of the oil chambers on both sides of the piston sliding in the inner cylinder is provided in the sub-tank via the oil chambers on both sides of the partition part. Communicating with the oil chamber on the inner peripheral side of the piston, and the other of the oil chambers on both sides of the piston is connected to the second chamber.
The hydraulic shock absorber according to any one of claims 1 to 4, which communicates with the oil chamber on the outer peripheral side of the partition wall.