JPH1038006A - Front fork - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow a front fork to properly generate position-dependent damping force, corresponding to the position of stroke of the front fork. SOLUTION: A cylindrical partition member 20 is arranged between an outer tube 11 and a damper cylinder 31 in order for a reservoir chamber 38 and an operation chamber 27 to be separately formed. A sliding member 67 for partitioning the operation chamber into an upper operation chamber 73A and a lower operation chamber 73B, is arranged on the tip part of an inner tube 12, and a check valve 66 for interrupting only the flow of operating fluid flowing from the lower operation chamber to the upper operation chamber, is arranged to the sliding member. Further, plural orifices a1 to a4 , b1 to b3 for connecting the lower operation chamber to the reservoir chamber are formed in the partition member along the axial direction of the partition member, and the upper operation chamber is connected to the reservoir chamber through a long hole 75.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a front fork that generates both a speed-dependent damping force and a position-dependent damping force.

[0002]

2. Description of the Related Art In a front fork of a motorcycle or the like, a damper device installed between an inner tube and an outer tube generally has a damping device proportional to a stroke of the front fork, that is, a speed of a piston sliding in a damper cylinder. Although the force is generated, it is preferable to change the damping force according to the stroke position of the front fork, that is, the stroke position of the piston.

That is, the stroke position of the front fork when one rider rides on a motorcycle (hereinafter referred to as "1
It is preferable to increase the compression-side damping force and the extension-side damping force as the compression stroke or the extension stroke of the front fork around the "G position" increases.
By doing so, small high-frequency vibrations in the vicinity of the 1G position of the front fork can be responded with a small damping force to improve the absorption of the high-frequency vibrations. On the other hand, the damping force can be increased to enhance the damping of the vehicle body.

Conventionally, in a rear cushion unit of a motorcycle provided with a suspension spring outside the rear damper device, the rear damper device is connected to a swing arm supporting a rear wheel via a link mechanism, and the rear link is used by the link mechanism. The spring constant of the suspension spring and the damping force of the rear damper device are increased in accordance with the stroke position of the cushion unit.

However, in the case of a front fork,
Since the front fork itself is a strength member, it is difficult to attach the front fork via the link mechanism as described above, and a position dependent inside the front fork that generates a damping force according to the stroke position of the front fork A damping force generating mechanism is installed.

As a front fork having a position-dependent damping force generating mechanism inside, a device described in Japanese Utility Model Laid-Open Publication No. Sho 62-56496 is known. This front fork is provided with a spring seat that has a through hole and partitions a reservoir chamber up and down, and a suspension spring and a detection spring are provided between the inner tube and the outer tube at the top of a damper device installed between the inner tube and the outer tube. Placed in series,
One end of the detection spring is supported by the spring seat, and an opening / closing member that can open and close the through hole is interposed between both springs.

In the front fork described in this publication, the detection spring detects the load (spring reaction force) of the suspension spring generated during the expansion and contraction stroke of the front fork, and the opening and closing member opens and closes the through hole of the spring seat. The oil flowing through the hole generates a damping force depending on the position of the front fork.

[0008]

In the front fork described in the above publication, the load setting at which the detection spring starts to expand and contract according to the expansion and contraction stroke of the front fork, that is, the expansion and contraction amount of the suspension spring, is determined by the wire diameter of the detection spring. And pitch, but this is a difficult task. For this reason, it is difficult to appropriately generate a position-dependent damping force corresponding to the stroke position of the front fork in the through hole.

In the front fork described in the above-mentioned publication, the suspension spring and the detection spring are connected in series. Therefore, when the suspension spring is replaced, the detection spring must be replaced accordingly. Maintenance becomes complicated.

An object of the present invention is to provide a front fork capable of appropriately generating a position-dependent damping force according to a stroke position of a front fork. is there.

[0011]

According to the first aspect of the present invention, an inner tube attached to a vehicle body is slidably fitted in an outer tube attached to an axle side. In the front fork, a damper cylinder is provided upright at a base end, and a speed-dependent damping force generating mechanism that generates a damping force depending on the speed of the expansion and contraction stroke of the front fork is provided in the damper cylinder. A cylindrical partition member is provided between the outer tube and the damper cylinder, and the partition member separates a reservoir chamber communicating with an oil chamber in the damper cylinder and a working chamber on the outer tube side. The inner tube has a distal end that slides in contact with the outer peripheral surface of the partition member and that divides the working chamber into an upper working chamber and a lower working chamber. A check valve for preventing only the flow of hydraulic oil from the lower working chamber to the upper working chamber is provided on the sliding member, and a plurality of check valves are provided on the partition member along the axial direction. Orifices are formed,
The orifice communicates the lower working chamber with the reservoir chamber, and the upper working chamber communicates with the reservoir chamber.

According to a second aspect of the present invention, in the first aspect of the invention, the plurality of orifices formed in the partition wall member are provided with a reduced opening area toward the base end of the outer tube. It is a thing.

The first aspect of the invention has the following operation. In the compression stroke of the front fork, a speed-dependent damping force depending on the stroke speed of the front fork is generated by a speed-dependent damping force generating mechanism in the damper cylinder.

Further, in the compression stroke of the front fork, a damping force is generated when hydraulic oil in the lower working chamber flows through the orifice by the action of a sliding member having an inner tube and a check valve. Since a plurality of orifices are provided along the axial direction of the partition member, the number of orifices in the lower working chamber increases and decreases depending on the stroke position of the sliding member corresponding to the expansion and contraction stroke of the front fork. The damping force generated when flowing through the orifice is a position-dependent damping force depending on the stroke position of the front fork.

As described above, the position-dependent damping force is generated by a plurality of orifices formed in the partition wall member along the axial direction, and the formation position and the orifice diameter of the orifice can be easily set. The position-dependent damping force according to the stroke position of the fork can be appropriately and easily generated.

A partition member having an orifice that generates a position-dependent damping force only supports a suspension spring, and is not operatively connected to the suspension spring.
For this reason, even if the suspension spring is replaced, there is no need to replace the partition member accompanying it, and maintenance of the front fork is easy.

The second aspect of the invention has the following operation. Since the opening areas of the plurality of orifices formed in the partition member are reduced toward the base end of the outer tube, the position-dependent damping force can be increased in accordance with the degree of compression of the front fork. .

[0018]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a half sectional view showing one embodiment of a front fork according to the present invention. FIG. 2 is a half cross-sectional view showing a central portion of the front fork of FIG. 1 in an enlarged manner. FIG. 3 is a half sectional view showing a lower portion of the front fork of FIG. 1 in an enlarged manner. FIG. 4 is an operation sectional view showing the operation of the check valve of FIG. FIG. 5 is a graph showing a position-dependent damping force characteristic of the front fork of FIG.

As shown in FIG. 1, an upright front fork 10 applied to a motorcycle includes an outer tube 1
1, the inner tube 12 is inserted, and both tubes 11
A suspension spring 13 and a damper device 14 are built in between the inner tube 12 and the inner tube 12. The inner tube 12 is supported on the vehicle body side, and the axle is supported on the axle bracket 15 of the outer tube 11. The front fork 10 shown in the drawing shows a maximum extension stroke state.

A first inner tube is provided on the inner periphery of the open end of the outer tube 11.
The guide bush 16 is provided with a second guide bush 17 on the outer periphery of the lower end portion of the inner tube 12. The first guide bush 16 is in sliding contact with the outer peripheral surface of the inner tube 12, and the second guide bush 17 is
The outer tube 11 and the inner tube 12 are configured to be slidable by sliding contact with the inner peripheral surface of the inner tube.

The lower end of the suspension spring 13 is supported by the outer tube 11 via a lower spring seat 18, a seat guide 19, a partition member 20 described below, and an axle bracket 15. The upper end of the suspension spring 13 has an upper spring seat 21, a lock nut 22,
It is supported by the inner tube 12 via a joint bolt 23 and a fork cap 24. The suspension spring 13 absorbs the impact force from the road surface.

The fork cap 24 is screwed and fixed to the upper end of the inner tube 12 so that the inner tube 12
Close the upper end of. A joint bolt 23 is screwed and fixed to the fork cap 24, and an upper end portion of a piston rod 40 described later is screwed and fixed to the joint bolt 23. The lock nut 22 is screwed into the upper end of the piston rod 40 and abuts on the joint bolt 23 to perform a function of preventing the piston rod 40 from loosening the joint bolt 23. The upper spring seat 21 is positioned in contact with the lock nut 22.

As shown in FIG. 1, the damper device 14 includes a damper cylinder 31 erected from the outer tube 11, a piston valve mechanism 34 having a piston 32 and a square hole 33, a bottom piston 35 and a bottom piston 35. And a base valve mechanism 37 having a needle valve 36. The piston valve mechanism 34 and the base valve mechanism 37 function as a speed-dependent damping force generating mechanism 25, and a speed-dependent damping force generated by the speed-dependent damping force generating mechanism 25 and a position-dependent damping force described later. Due to the position-dependent damping force generated by the generating mechanism 26, the expansion and contraction sliding of the outer tube 11 and the inner tube 12 caused by the absorption of the impact force by the suspension spring 13 is suppressed.

As shown in FIGS. 2 and 3, the damper cylinder 31 is disposed in the outer tube 11, and the cylindrical partition member 20 is erected between the damper cylinder 31 and the outer tube 11. . A reservoir chamber 38 is formed surrounded by the partition member 20 and the damper cylinder 31, and a working chamber 27 is formed surrounded by the partition member 20 and the outer tube 11. A communication hole 39 is opened in the damper cylinder 31, and the inside of the damper cylinder 31 (the base valve chamber 45 </ b> C) and the reservoir chamber 38 communicate with each other through the communication hole 39.

The piston 32 of the piston valve mechanism 34 is fixed to a piston rod 40 via a piston holder 41. The inside of the damper cylinder 31 is defined by the piston 32 into an upper chamber 45A and a lower chamber 45B.
A growth side flow path (not shown) and a compression side flow path 42 are formed in the piston 32 so as to penetrate in the axial direction, and a growth side valve 43 and a compression side valve (check valve) 4
4 are provided.

The pressure side valve 44 is connected to the front fork 10
In the compression stroke, the stroke speed of the front fork 10, that is, the piston 3 with respect to the damper cylinder 31
2, when the relative speed is medium or high, the valve is opened by the oil (oil surface H) guided from the lower chamber 45B to the pressure side flow path 42, and this oil is guided to the upper chamber 45A, and the upper chamber 45A
Eliminate the negative pressure.

When the stroke speed of the front fork 10, that is, the relative speed of the piston 32 with respect to the damper cylinder 31 is medium or high during the extension stroke of the front fork, the extension valve 43 extends from the upper chamber 45A to the extension side flow path. Is deformed by the oil led to the lower chamber 45B and generates a speed-dependent damping force on the extension side.

Further, in the piston valve mechanism 34, 2
The riding hole 33 is formed in the piston holder 41, as shown in FIG. 2, and allows the upper chamber 45A and the lower chamber 45B to communicate with each other. In the compression stroke or the extension stroke of the front fork 10, when the stroke speed of the front fork 10, that is, the relative speed of the piston 32 with respect to the damper cylinder 31, is low, the speed-dependent pressure side or the extension while the oil flows through the square hole 33. Side damping force is generated.

The bottom piston 35 of the base valve mechanism 37 is, as shown in FIG.
9 is fixed. A pressure-side flow path (not shown) and an expansion-side flow path 50 are formed in the bottom piston 35 so as to penetrate in the axial direction, and a compression-side valve 51 and an expansion-side valve (check valve) 52 are provided at both axial end surfaces. Is attached. This bottom piston 35 allows the base valve chamber 45C to be connected to the lower chamber 4
5B. The piston holder 49 has a hollow shape, and is fixed to the axle bracket 15 via a hollow center bolt 53.

During the compression stroke of the front fork 10, the pressure side valve 51 operates when the stroke speed of the front fork 10, that is, the relative speed of the piston 32 with respect to the damper cylinder 31 is medium to high.
When the oil corresponding to the volume of the piston rod 40 that enters the inside 1 is guided from the lower chamber 45B to the pressure side flow path, the oil is bent and deformed, and the oil is dissipated through the base valve chamber 45C and the communication hole 39 into the reservoir chamber 38. And a pressure-dependent speed-dependent damping force is generated.

In the extension valve 52, during the extension stroke of the front fork 10, oil equivalent to the volume of the piston rod 40 retreating from the damper cylinder 31 flows from the reservoir chamber 38 to the communication hole 39 and the base valve chamber 45C.
The valve is opened when the flow reaches the extension side flow path 50 via the valve, and the oil is guided to the lower chamber 45B, and the negative pressure in the lower chamber 45B is eliminated.

The bottom needle valve 36 in the base valve mechanism 37 is provided with a bottom needle valve adjuster 55
And are integrally rotated. By rotating the bottom needle valve adjuster 55, the bottom needle valve 3
6 changes the flow path area with the piston holder 49. The bottom needle valve 36 allows the lower chamber 45B and the base valve chamber 45C to communicate with each other via the bottom passage 56 of the piston holder 49. Reference numeral 56A denotes a click mechanism.

During the compression stroke of the front fork 10, the bottom needle valve 36
When the stroke speed of the piston 32, that is, the relative speed of the piston 32 with respect to the damper cylinder 31, is low, oil corresponding to the volume of the piston rod 40 that enters the damper cylinder 31 is supplied from the lower chamber 45B to the bottom needle valve 36 and the piston holder 49. Through the bottom passage 56, the base valve chamber 45C, and the communication hole 39.
Flow to While oil flows through the flow path between the bottom needle valve 36 and the piston holder 49, a speed-dependent pressure-side damping force is generated.

In the compression stroke of the front fork 10, when the relative speed between the damper cylinder 31 and the piston 32 is low, the bottom needle valve 36 and the piston holder 4
9 is adjusted by rotating the bottom needle valve adjuster 55 to change the flow path area.

Therefore, as shown in FIG. 1, depending on the piston valve mechanism 34 and the base valve mechanism 37 constituting the speed-dependent damping force generating mechanism 25, during the compression stroke of the front fork 10, two piston valve mechanisms 34
When oil flows through the passage hole 33 and the flow path between the bottom needle valve 36 of the base valve mechanism 37 and the piston holder 49, a damping force at a low pressure side depending on the stroke speed of the front fork 10 is generated. When the oil bends and deforms the compression-side valve 31 of the base valve mechanism 37, a damping force at the compression-side medium speed that depends on the stroke speed of the front fork 10 is generated.

On the other hand, in the extension stroke of the front fork 10, when oil flows through the square hole 33 of the piston valve mechanism 34, a damping force at the extension side low speed dependent on the stroke speed of the front fork 10 is generated, Further, when the extension side valve 43 of the piston valve mechanism 34 is flexibly deformed, a damping force at the extension side medium speed depending on the stroke speed of the front fork 10 is generated. The base valve mechanism 37 hardly generates a damping force during the extension stroke of the front fork 10.

Here, as shown in FIG. 2, a rod guide case 58 for supporting a rebound spring 57 is mounted on the upper end opening of the damper cylinder 31, and a rod guide 59 is accommodated in the rod guide case 58. You. Reference numeral 60 denotes an O-ring. The rod guide 59
A third guide bush 61 is fixed to the inner periphery of the
The guide bush 61 is configured to be able to slide on the outer peripheral surface of the piston rod 40.

An oil seal 62 is attached to the lower end opening of the outer tube 11 so as to be adjacent to the first guide bush 16 in the axial direction. This oil seal 62
Is mounted on the outer tube 11 by a washer 63 and a stopper ring 64, and a dust seal 65 is further mounted adjacent to the oil seal 62. The oil in the upper working chamber 73A described later is guided to the oil seal 62 from an opening hole 54 opened in the inner tube 12, and is maintained in a wet state.

The position-dependent damping force generating mechanism 26
As shown in FIG. 1, a plurality of orifices a ₁ and a
₂ , comprising a partition member 20 having a, a ₃ , a ₄ , b ₁ , b ₂ , and b ₃ , and a sliding member 67 provided at a lower end of the inner tube 12 and having a check valve 66. And
It is provided in parallel with the speed-dependent damping force generation mechanism 25 described above.

As shown in FIG. 3, the partition member 20 is supported upright on the axle bracket 15 by a bottom piece 68 fitted to the inner periphery of the lower end. As shown in FIG. 2, the sheet guide 19 is fixed to the upper end of the partition member 20, and a fourth guide bush 69 is mounted on the outer periphery of the sheet guide 19. When the front fork 10 expands and contracts, the fourth guide bush 69 is connected to the inner tube 12.
Can be in sliding contact with the inner peripheral surface of the.

The sliding member 67 is provided in the inner tube 12.
The check valve 66 is loosely fitted to the inner periphery of the housing member 70 attached to the lower end of the housing so as to be movable in the axial direction. The housing member 70 is positioned on the inner tube 12 by the washer 71. Check valve 6
The control of the axial movement 6 is performed by the check valve 66 abutting on one of the washer 71 and a bent portion 72 formed by bending inside the housing member 70. The check valve 66 of the sliding member 67 is slidably provided on the outer peripheral surface of the partition member 20, and the working chamber 27 formed between the outer tube 11 and the partition member 20 is different from the upper working chamber 73A. It is partitioned into a lower working chamber 73B.

During the compression stroke of the front fork 10, the check valve 66 makes the sliding member 67 move to the lower working chamber 73 B.
4A, the oil in the lower working chamber 73B is pushed up by the oil in the lower working chamber 73B to abut the washer 71 to close the valve, and the lower working chamber 73B is closed to the upper working chamber 73A as shown in FIG. Block oil flow. In addition, since the sliding member 67 increases the volume of the lower working chamber 73B during the extension stroke of the front fork 10, the check valve 66 is pushed down by the oil in the upper working chamber 73A as shown in FIG. Then, the hydraulic oil in the upper working chamber 73A flows into the lower working chamber 73B through the notch 74 formed at the lower end of the check valve 66, and the valve is opened. .

As shown in FIG. 1 and FIG.
Orifices a ₁ , a ₂ , a formed on the lower end side of
₃ , a ₄ , b ₁ , b ₂ , and b ₃ are formed along the axial direction of the partition member 20, and the lower working chamber 73B and the reservoir chamber 38
And can communicate. The orifices b ₁ , b ₂ , b ₃
The opening areas of the orifices a ₁ , a ₂ , a ₃ , and a ₄ are provided closer to the base end of the outer tube 11 than the orifices a ₁ , a ₂ , a ₃ , and a ₄ , that is, to the lower end of the partition member 20. It is set to a smaller area than. Front fork 10
In the compression stroke, causes the sliding member 67 reduces the volume of the lower working chamber 73B, the oil orifice a ₁ in the lower working chamber _{73B, a 2, a 3,} a 4, b 1, b 2, b 3 Through the front fork 10
, That is, the compression side damping force depending on the stroke position of the sliding member 67 is generated.

The orifices a ₁ , a ₂ , a ₃ , a ₄ ,
FIG. 5 shows a position-dependent damping force characteristic generated by b ₁ , b ₂ , and b ₃ . This position-dependent damping force characteristic is obtained by using the sliding member 6.
7 is centered on the 1G position of the front fork 10 at the position indicated by the two-dot chain line in FIGS. 1 and 2, and when the front fork 10 is at the extended stroke position than the 1G position, no position-dependent damping force is generated. Further, even if the front fork 10 is at the compression stroke position rather than the 1G position, no position-dependent damping force is generated near the 1G position. At the compression stroke position where the front fork 10 is closer to the most compression side than the 1G position, the orifice a
_{1, a 2, a 3,} a 4, b 1, b 2, b 3 by the position-dependent damping force is generated. The front fork 1 comes to the position where the sliding member 67 is lowered than the orifice b ₃ position
At the time of the maximum compression of 0, the lower working chamber 73B becomes an oil lock chamber, and the collision of the sliding member 67 with the axle bracket 15 is avoided.

As shown in FIGS. 1 and 2, an elongated hole 75 extending in the axial direction is formed at the upper end of the partition wall member 20. A plurality (for example, three or four) of the long holes 75 are formed in the circumferential direction of the partition member 20 so that the upper working chamber 73A and the reservoir chamber 38 can communicate with each other. The long hole 75 allows the oil in the upper working chamber 73A to flow into the reservoir chamber 38 during the extension stroke of the front fork 10, but is set to an opening area where no damping force is generated at this time.

Reference numeral 76 in FIG. 1 denotes a dust boot, which protects the insertion portion of the inner tube 12 inserted into the outer tube 11 from mud or the like. Reference numeral 77 is
This is a brake hose stopper for supporting a brake hose (not shown) on the front fork 10.

Next, the operation of the position-dependent damping force generating mechanism 26 configured as described above will be described. In the compression stroke of the front fork 10, as described above, the square hole 3 of the piston valve mechanism 34 in the speed-dependent damping force generation mechanism 25 is used.
3 and the pressure side valve 51 and the bottom needle valve 36 of the base valve mechanism 37 generate a pressure side damping force depending on the stroke speed of the front fork 10.

Further, in the compression stroke of the front fork 10, a pressure-side damping force is generated by the position-dependent damping force generating mechanism 26 depending on the stroke position of the front fork 10.

That is, when the sliding member 67 is lowered during the compression stroke of the front fork 10, the check valve 66 of the sliding member 67 is closed, so that the oil in the lower working chamber 73B causes the check valve 66 to close. The orifices a ₁ , a ₂ , a
_3, a _4, b _1, flows through the b _2, b ₃ to the reservoir chamber 38. At this time, the compression stroke of the front fork 10 is large, and the sliding member 67 has the orifices a ₃ and a ₃
When reaching the position between the _4, since the oil in the lower working chamber 73B flows into the reservoir chamber 38 through the orifice _{a 4, b 1, b 2} , b 3, the oil orifice a _1, a
₂ , a ₃ , a ₄ , b ₁ , b ₂ , b ₃ and reservoir chamber 3
The damping force is larger than when flowing to 8, and the damping force depends on the compression stroke position of the front fork 10.

[0050] In the compression stroke of the front fork 10, when the sliding member 67 is lowered down to the orifice b ₁ position near the orifice b ₁ is the oil in the lower working chamber 73B,
b _2, b ₃ via stream into the reservoir chamber 38, the orifice b _1, b _2, the opening area of the orifice a ₁ of b _3, a
Since it is smaller than ₂ , a ₃ and a ₄ , the damping force is sharply increased and the oil lock action is exhibited. Sliding member 67
There reaches the orifice b ₃ below lower working chamber 73B becomes oil lock chamber, the sliding member 67 and the axle bracket 1
5 is avoided.

In the above-described compression stroke of the front fork 10, the pressure in the upper working chamber 73A is negative, so that the oil in the reservoir chamber 38 flows into the upper working chamber 73A through the long hole 75 of the partition member 20. Large compression stroke of the front fork 10, when the sliding member 67 is positioned between the orifice a ₃ and a ₄ for example, oil in the reservoir chamber 38, the long hole 75 only or, orifice a _1, a _2,
even after a ₃ to flow into the upper working chamber 73A.

On the other hand, in the extension stroke of the front fork 10, as described above, depending on the stroke speed of the front fork 10 due to the square hole 33 of the piston valve mechanism 34 and the extension valve 43 in the speed-dependent damping force generation mechanism 25. The extended extension damping force is generated.

In the extension stroke of the front fork 10, no position-dependent damping force is generated by the position-dependent damping force generating mechanism 26. That is, in the extension stroke of the front fork 10, the sliding member 67 rises and the check valve 66 is opened, so that the oil in the upper working chamber 73A flows into the lower working chamber 73B via the check valve 66. Furthermore, from the orifice _{a 1, a 2, a 3} , a 4, b 1, b 2, b 3 that to lower working chamber 73B has an opening state, oil in the reservoir chamber 38 to lower working chamber 73B Flows. Thus, the negative pressure in the lower working chamber 73B is released. At this time, the oil in the upper working chamber 73A flows from the long hole 75 to the reservoir chamber 38.

According to the above embodiment, the following effects are obtained. The front fork 10 is provided with a position-dependent damping force generating mechanism 26 in parallel with the speed-dependent damping force generating mechanism 25. The speed-dependent damping force generating mechanism 25 is connected to the piston valve mechanism 34 and the base valve mechanism of the damper device 14. 37, the position-dependent damping force generating mechanism 26 includes a partition member 20 having orifices a ₁ , a ₂ , a ₃ , a ₄ , b ₁ , b ₂ , and b ₃ , and a check valve 66. And the sliding member 67 at the tip of the inner tube 12 provided with the front fork. And the position-dependent damping force generating mechanism 26 reduces the position dependence of the front fork 10 depending on the compression stroke position. It is possible to generate a force.

In the position-dependent damping force generating mechanism 26, a plurality of orifices a ₁ , a ₂ , and a plurality of orifices are formed in the partition member 20 along the axial direction thereof.
_{a 3, a 4, b 1} , b 2, b 3 by generated, these orifices _{a 1, a 2, a 3} , a 4, b 1, b 2, b 3
Since the formation position and the orifice diameter can be easily set, a position-dependent damping force corresponding to the compression stroke position of the front fork 10 can be appropriately and easily generated.

Further, in the position-dependent damping force generating mechanism 26, the opening areas of the plurality of orifices a ₁ , a ₂ , a ₃ , a ₄ , b ₁ , b ₂ , and b ₃ formed in the partition wall member 20 are determined. Is provided to decrease toward the lower end of the partition member 20, so that the position-dependent damping force can be increased in accordance with the degree to which the front fork 10 is compressed.

A partition member 20 having orifices a _{1 to} a ₄ and b _{1 to} b ₃ for generating a position-dependent damping force.
Only supports the suspension spring 13 and is not operatively connected to the suspension spring 13. For this reason, even if the suspension spring 13 is replaced, it is not necessary to replace the partition member 20 accompanying the replacement, and maintenance of the front fork 10 is easy.

In the above embodiment, the orifice a
₁ , a ₂ , a ₃ and a ₄ have the same diameter, and the orifice b
_{Although the case where 1} , b ₂ , and b ₃ have the same diameter smaller than orifices a ₁ , a ₂ , a ₃ , and a ₄ has been described, a plurality of the orifices a The opening area of the formed orifice may be set so as to gradually decrease toward the lower end of the partition member 20.

[0059]

As described above, according to the front fork according to the present invention, the position-dependent damping force can be appropriately generated according to the stroke position of the front fork.

[Brief description of the drawings]

FIG. 1 is a half sectional view showing one embodiment of a front fork according to the present invention.

FIG. 2 is a half sectional view showing an enlarged central portion of the front fork in FIG. 1;

FIG. 3 is an enlarged half sectional view showing a lower portion of the front fork in FIG. 1;

FIG. 4 is an operation sectional view showing an operation of the check valve of FIG. 2;

FIG. 5 is a graph showing a position-dependent damping force characteristic of the front fork in FIG. 1;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 Front fork 11 Outer tube 12 Inner tube 14 Damper device 20 Partition member 25 Speed-dependent damping force generating mechanism 26 Position-dependent damping force generating mechanism 27 Working chamber 31 Damper cylinder 34 Piston valve mechanism 37 Base valve mechanism 38 Reservoir chamber 45A chamber 45B lower chamber 45C base valve chamber 66 the check valve 67 slide member 73A upper working chamber 73B lower working chamber 75 long holes _{a 1, a 2, a 3} , a 4, b 1, b 2, b 3 orifice

Claims (2)

[Claims] An inner tube attached to a vehicle body is slidably fitted into an outer tube attached to an axle side, and a damper cylinder is erected at a base end of the outer tube. In a front fork in which a speed-dependent damping force generating mechanism that generates a damping force depending on the speed of an extension stroke of a front fork is provided in a cylinder, a cylindrical shape is provided between the outer tube and the damper cylinder. A partition member is provided, the partition member defines a reservoir chamber communicating with the oil chamber in the damper cylinder, and a working chamber on the outer tube side, and is formed at a tip end of the inner tube. A sliding member that slides on the outer peripheral surface of the partition member and partitions the working chamber into an upper working chamber and a lower working chamber is provided. A check valve for preventing only the flow of hydraulic oil from the upper working chamber to the upper working chamber is provided, and a plurality of orifices are formed in the partition member along the axial direction. A front chamber for communicating with the reservoir chamber, and the upper working chamber is configured to communicate with the reservoir chamber. 2. The front fork according to claim 1, wherein the plurality of orifices formed in the partition member have a reduced opening area toward the base end of the outer tube.