JP2001330076A - Inverted hydraulic shock absorber - Google Patents

Abstract

(57) [Summary] [PROBLEMS] In an inverted type hydraulic shock absorber, while compensating for a compression side damping force by a hydraulic oil throttling action of a partition member provided on an outer periphery of a damper cylinder, the steering stability is reduced by reducing an extension stroke resistance. To secure. A partition member (3) supported by a damper cylinder (21) and provided with an oil passage (33A) that slidably contacts an inner periphery of an inner tube (12) and allows hydraulic oil in an oil reservoir (35) to flow therethrough.
In the inverted type hydraulic shock absorber 10 having the opening 3, the communication region of the oil passage 33 </ b> A of the partition member 33 is narrowed in the compression stroke, and the communication member of the partition member 33 is opened in the extension stroke (70). Check valve 71).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inverted hydraulic shock absorber in which a damper is installed inside an outer tube on the vehicle body side and an inner tube on the wheel side, and more particularly to an inverted front fork for a motorcycle or the like.

[0002]

2. Description of the Related Art Japanese Unexamined Patent Publication (Kokai) No. Hei 6-09054 discloses that an outer tube on a vehicle body side and an inner tube on a wheel side are slidably fitted to each other, a piston rod is erected on the inner tube, and the piston rod is connected to a damper cylinder. There is disclosed an inverted hydraulic shock absorber in which an oil reservoir and a gas chamber are formed inside an outer tube and an inner tube.

In this inverted hydraulic shock absorber, a partition member (throttle member) having a plurality of orifices is provided on the outer periphery of the damper cylinder. Thereby, in the compression stroke,
Hydraulic oil at the lower portion of the oil reservoir flows to the upper portion of the oil reservoir through the orifice of the partition member, and the orifice generates a pressure-side damping force to supplement the pressure-side damping force generated by the damper.

[0004]

However, in the prior art, the orifice of the partition member also affects the extension stroke.
That is, in the extension stroke, when the hydraulic oil in the upper part of the oil reservoir should return to the lower part of the oil reservoir through the orifice of the partition member,
This orifice acts as a resistance and slows its return. This makes it difficult for the front fork to extend smoothly, so that the front fork is in a so-called packed state (a state in which the front fork is kept compressed), and the front wheel side tends to fall forward.

SUMMARY OF THE INVENTION An object of the present invention is to provide an inverted hydraulic shock absorber in which a hydraulic damping action of a partition member provided on the outer periphery of a damper cylinder compensates for a compression-side damping force, reduces resistance during an extension stroke, and provides an appropriate control. The goal is to ensure stability.

[0006]

According to a first aspect of the present invention, an outer tube on a vehicle body side and an inner tube on a wheel side are slidably fitted to each other, and a piston rod is erected on the inner tube. Into the damper cylinder, forming an oil reservoir and a gas chamber inside the outer tube and the inner tube, supported by the damper cylinder, sliding on the inner periphery of the inner tube, and flowing the hydraulic oil in the oil reservoir. In an inverted hydraulic shock absorber having a partition member provided with an oil passage that can be made, a throttle member that narrows an oil passage communication region of the partition member in a compression stroke and opens an oil passage communication region of the partition member in an extension stroke. Is provided.

According to a second aspect of the present invention, in the first aspect of the invention, the throttle member further comprises a check valve having an orifice having a smaller opening than the oil passage of the partition member. In the stroke, the oil passage communication region of the partition member is shut off to use the orifice as a flow path for the hydraulic oil, and in the extension stroke, the oil passage communication region of the partition member is opened.

[0008] The invention according to claim 3 is the invention according to claim 1 or 2.
The partition member may further include a spring receiver that supports a suspension spring between the partition member and the inner tube.

[0009]

According to the first aspect of the present invention, the following operations are provided. In the compression stroke, the throttle member narrows the oil passage communication area of the partition member.
The air flows through the throttle passage of the throttle member to the upper portion of the oil reservoir, and generates a pressure-side damping force in the throttle passage of the throttle member to supplement the pressure-side damping force generated by the damper.

In the extension stroke, the throttle member opens the oil passage communication area of the partition member. Therefore, the hydraulic oil in the upper part of the oil reservoir does not pass through the throttle passage of the throttle member, but smoothly returns to the lower part of the oil reservoir through the oil passage of the partition member. As a result, the front fork extends smoothly, and the front fork does not enter a packed state (a state in which the front fork is kept compressed), and steering stability can be ensured.

According to the second aspect of the invention, the following operations are provided. In the compression stroke, the check valve constituting the throttle member shuts off the oil passage communication area of the partition member and uses the orifice as a flow path.
It flows to the upper part of the oil reservoir through the orifice of the check valve, and a pressure-side damping force is generated by the orifice of the check valve to supplement the pressure-side damping force generated by the damper.

In the extension stroke, the check valve opens the oil passage communication area of the partition member. Therefore, the hydraulic oil in the upper part of the oil reservoir returns to the lower part of the oil reservoir smoothly through the oil passage of the partition member without passing through the orifice of the check valve. As a result, the front fork extends smoothly, and the front fork does not become packed, so that steering stability can be ensured.

According to the third aspect of the invention, the following operation is provided. By providing the partition member with a spring receiver that supports the suspension spring, the number of parts and the number of assembly steps can be simplified as compared with a case where the partition member and the spring receiver are provided separately.

[0014]

1 is an overall sectional view showing a front fork according to a first embodiment, FIG. 2 is an enlarged sectional view of a lower portion of FIG. 1, FIG. 3 is an enlarged sectional view of an intermediate portion of FIG. 1, and FIG. 1 is an enlarged cross-sectional view of FIG. 1, FIG. 5 shows the operation of the throttle member, (A) is a cross-sectional view at the time of compression, (B) is a cross-sectional view at the time of expansion, FIG. 6 shows a partition member, and (A) is a cross-section. FIG. 7 (B) is a plan view, FIG. 7 shows a check valve, FIG. 7 (A) is a sectional view, FIG. 8 (B) is a plan view, FIG. 8 is an overall sectional view showing a front fork of the second embodiment, FIG. 8 is an enlarged sectional view of the lower part of FIG. 8, FIG. 10 is an enlarged sectional view of the middle part of FIG. 8, and FIG. 11 is an enlarged sectional view of the upper part of FIG.

(First Embodiment) (FIGS. 1 to 7) As shown in FIGS. 1 to 4, a front fork 10 (hydraulic shock absorber) includes a wheel side tube (inner tube) inside a vehicle body side tube (outer tube) 11. Tube 12 is slidably inserted, and a suspension spring 13 is inserted between the tubes 11 and 12.
In addition, 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 to 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 to the upper outer peripheral portion 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 damper 1 is provided at the upper end of the body side tube 11.
4 damper cylinder 21 (upper cylinder tube 21A)
Is screwed via an O-ring. A cap 19 is screwed to the inner periphery of the upper end of the damper cylinder 21 in a liquid-tight manner via an O-ring. 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. The base end of a piston rod (hollow rod) 22 of the damper 14 is screwed to the bottom bolt 24 and locked by a lock nut 24A.
The tip of the piston rod 22 is connected to the damper cylinder 21
Has been inserted. The piston rod 22 is supported by a bush 25A of a rod guide 25 screwed into the lower end opening of the damper cylinder 21 (lower cylinder tube 21B),
It is inserted inside 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)
Between a spring ring 34 attached to an outer peripheral surface of a leading end portion of a partition member 33 supported via a metal washer 31 and a Teflon (registered trademark) washer 32 on a stopper ring 30 attached to an outer peripheral surface of an intermediate portion of the above. It is interposed. Also,
An oil reservoir 35 and a gas chamber 36 are provided inside the vehicle body side tube 11 and the wheel side tube 12, and the gas confined in the gas chamber 36 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 reservoir 35 moves up and down from below the partition member 33 due to expansion and contraction of the vehicle body side tube 11 and the wheel side tube 12 of the front fork 10, and in FIG. , L
B is the oil level at the time of maximum compression. As shown in FIG. 6, the partition member 33 includes a bush 37 that slides on the inner periphery of the wheel-side tube 12 and a plurality of long-hole oil passages 33 </ b> A that allow hydraulic oil in the oil reservoir 35 to flow vertically. Prepare.

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 38 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 is passed 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, the guide pipe 51 is screwed to the above-mentioned cap 19 screwed to the upper end of the upper cylinder tube 21A. 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 in the small diameter part 51C.
The valve housing 52 is in liquid-tight contact with the inner peripheral portion of the lower cylinder tube 21B, 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 4.
3A and a base valve chamber 53, which can communicate with each other.
Extension side flow path 5 that enables communication between A and base valve chamber 53
5 is provided. 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 side of the cap 19 (the gas chamber 36).
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 inserted into 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 is extended, 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 reservoir 3 attached to the outer peripheral surface of the piston rod 22.
In order to bring the oil of No. 5 into the damper cylinder 21, a passage 63 for returning the oil to the oil reservoir 35 is provided. That is, the passage 63 is formed by the oil seal 6 on the inner periphery of the partition member 61.
4 and a small diameter portion 51C formed on the upper part of the guide pipe 51
(Not shown) formed between the upper cylinder tube 21A and the large-diameter hole 63 formed in the upper part of the upper cylinder tube 21A.
B is formed.

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 the 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 fitted to the oil lock collar 23 provided at the lower end of the wheel side tube 12, and both of them are engaged. The oil that has been compressed between them causes an oil lock action 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, in the front fork 10, the damping force generated in the base valve device 50 during the above-described compression is due to the oil flow corresponding to the volume of the piston rod 22 entering the damper cylinder 21. There is a limit to enhancement. Therefore, in the present embodiment, the following configuration is provided to reinforce the pressure-side damping force generated in the base valve device 50.

That is, the front fork 10 is
3, as shown in FIG. 3 and FIG. 5, a throttle member 70 is attached, the communication region of the oil passage 33A of the partition member 33 is narrowed in the compression stroke, and the communication region of the oil passage 33A is opened in the extension stroke. .

Specifically, the diaphragm member 70 is connected to the partition member 3.
3 comprises a check valve 71 (FIG. 7) slidably mounted on the outer periphery of the supported damper cylinder 21 and having an orifice 71A having a smaller opening than the oil passage 33A of the partition member 33. In the compression stroke, the check valve 71 is moved upward by the flow of hydraulic oil from the lower part to the upper part of the oil reservoir 35 as shown in FIG. The orifice 71A is in contact with the sheet 33B and cuts off the communication area of the oil passage 33A of the partition member 33, so that the orifice 71A is used as a flow path for hydraulic oil. On the other hand, in the extension stroke, the check valve 71 is moved downward by the flow of hydraulic oil from the upper part to the lower part of the oil reservoir 35, as shown in the right half of FIG. Is separated from the valve seat 33B by the valve stopper 72 on the outer periphery of the damper cylinder 21 to open the communication area of the oil passage 33A of the partition member 33.

Therefore, according to the present embodiment, the following operations are provided. In the compression stroke, the check valve 71 constituting the throttle member 70 blocks the communication area of the oil passage 33A of the partition member 33 and uses the orifice 71A as a flow path. The oil flows from the oil passage of the member 33 to the upper part of the oil reservoir 35 through the orifice 71A of the check valve 71,
A pressure-side damping force is generated by the orifice 71A of the check valve 71, and compensates for the pressure-side damping force generated by the base valve device 50 of the damper 14.

In the extension stroke, the check valve 71 opens the communication area of the oil passage 33A of the partition member 33. Therefore, the hydraulic oil in the upper part of the oil reservoir 35 smoothly returns to the lower part of the oil reservoir 35 through the oil passage of the partition member 33 without passing through the orifice 71A of the check valve 71. As a result, the front fork 10 extends smoothly, and the front fork 10 does not enter a packed state (a state in which the front fork 10 remains compressed), thereby ensuring steering stability.

By providing the partition member 33 with the spring receiver 34 for supporting the suspension spring 13, the number of parts and the number of assembling steps can be simplified as compared with the case where the partition member 33 and the spring receiver 34 are provided separately. .

Second Embodiment (FIGS. 8 to 11) The second embodiment is substantially different from the first embodiment in that a partition member 80 instead of the partition member 33 is directly connected to the lower cylinder tube 21B. Not supported, upper cylinder tube 21
The partitioning member 80 is supported by, for example, press-fitting the base end of the partitioning member 80 into a perforated cylinder 81 (having a large number of through-holes 81A) fixed to A. The partition member 80 also includes the spring receiver 34 and the bush 37, like the partition member 33. The partition member 80 has an annular space between the outer periphery of the damper cylinder 21 and upper and lower oil passages 80 </ b> A of the oil reservoir 35.

A diaphragm member 70 (specifically, an orifice 71) similar to that in the first embodiment is provided on the partition member 80.
A check valve 71) provided with A is attached, the communication region of the oil passage 80A of the partition member 80 is narrowed in the compression stroke, and the communication region of the oil passage 80A is opened in the extension stroke. Specifically, during the compression stroke, the check valve 71 is moved upward by the flow of hydraulic oil from the lower part to the upper part of the oil reservoir 35 as shown in the left half of FIG. Contact 80B,
The communication area of the oil passage 80A of the partition member 80 is shut off, and the orifice 71A is used as a flow path for the hydraulic oil. On the other hand, during the extension process,
The check valve 71 is moved downward by the flow of hydraulic oil from the upper part to the lower part of the oil reservoir 35 as shown in the right half of FIG. Is stopped by the valve stopper 72 of
The communication area of the oil passage 80A of the partition member 80 is opened. Therefore, the second embodiment has the same operation as that of the first embodiment.

Although the embodiments of the present invention have been described in detail with reference to the drawings, the specific configuration of the present invention is not limited to the embodiments, and the design can be changed within a range not departing from the gist of the present invention. The present invention is also included in the present invention. For example, the partition member of the present invention does not necessarily have to be used as a spring receiver for a suspension spring.

[0047]

As described above, according to the present invention, in the inverted hydraulic shock absorber, the hydraulic damping force of the partition member provided on the outer periphery of the damper cylinder supplements the compression damping force, and the resistance of the extension stroke is reduced. In addition, appropriate steering stability can be ensured.

[Brief description of the drawings]

FIG. 1 is an overall sectional view showing a front fork according to a first embodiment.

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.

5A and 5B show the operation of the throttle member, wherein FIG. 5A is a cross-sectional view when compressed, and FIG. 5B is a cross-sectional view when expanded.

FIG. 6 shows a partition member, (A) is a sectional view,
(B) is a plan view.

FIG. 7 shows a check valve, (A) is a sectional view,
(B) is a plan view.

FIG. 8 is an overall sectional view showing a front fork according to a second embodiment.

FIG. 9 is an enlarged sectional view of the lower part of FIG. 8;

FIG. 10 is an enlarged sectional view of an intermediate portion of FIG. 8;

FIG. 11 is an enlarged cross-sectional view of the upper part of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Front fork (inverted hydraulic shock absorber) 11 Body side tube (outer tube) 12 Wheel side tube (inner tube) 13 Suspension spring 14 Damper 21 Damper cylinder 22 Piston rod 33 Partition member 33A Oil passage 34 Spring receiver 35 Oil reservoir 36 gas chamber 70 throttle member 71 check valve 71A orifice 80 partition member 80A oil passage

Claims (3)

[Claims] 1. An outer tube on a vehicle body and an inner tube on a wheel are slidably fitted to each other, a piston rod is erected on the inner tube, and the piston rod is inserted into a damper cylinder. Forming an oil reservoir chamber and a gas chamber therein, and having a partition member provided with an oil passage which is supported by a damper cylinder, slidably contacts the inner periphery of the inner tube, and allows hydraulic oil in the oil reservoir chamber to flow therethrough. An inverted hydraulic shock absorber, comprising: a throttle member that narrows an oil passage communication area of a partition member in a compression stroke and opens an oil passage communication area of a partition member in an extension stroke. . 2. The throttle member comprises a check valve provided with an orifice having a smaller opening than the oil passage of the partition member. The check valve cuts off the oil passage communication region of the partition member during the compression stroke so that the orifice is closed with hydraulic oil. 2. The inverted hydraulic shock absorber according to claim 1, wherein the hydraulic passage of the partition member is opened during the extension stroke. 3. The inverted hydraulic shock absorber according to claim 1, wherein the partition member includes a spring receiver that supports a suspension spring between the partition member and the inner tube.