JP2001330073A - Hydraulic buffer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ensure the guide function of a piston rod by a rod guide device and the seal function of a damper cylinder even when the piston rod inserted in the damper cylinder of a hydraulic buffer is bent. SOLUTION: In the hydraulic buffer 10, a rod guide device 80 comprises a rod guide 82 supported in a floating state at a support part 73, situated on the inner periphery of the opening part of a damper cylinder 21, through an annular elastic sealant 81; a bush 83 situated internally of the rod guide 82 and guiding a piston rod 22; and an oil seal 84 situated internally of the rod guide 82 and sealing the damper cylinder 21.

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 having a damper inside a vehicle body side tube and a wheel side tube.

[0002]

2. Description of the Related Art In Japanese Patent Application Laid-Open No. H11-171078, a vehicle body side tube and a wheel side tube are slidably fitted, and a damper cylinder is erected on one of the vehicle body side tube and the wheel side tube. And a piston rod standing on the other of the wheel side tube and inserted into the damper cylinder while supporting the piston rod with a rod guide device provided at the opening of the damper cylinder.

In this hydraulic shock absorber rod guide device,
A rod guide is fixedly sealed to the inner periphery of the opening of the damper cylinder, a bush for guiding the piston rod is fixedly provided in the rod guide, and an oil seal for sealing the damper cylinder is provided in the rod guide. .

[0004]

However, in the prior art rod guide device, since the rod guide is fixed to the opening of the damper cylinder, the hydraulic shock absorber receives an external force such as a side force and the piston rod flexes. In this case, the rod guide cannot follow the deflection of the piston rod and cannot tilt or eccentric with respect to the center axis of the damper cylinder. For this reason, a large friction is generated between the bush fixed to the rod guide and the piston rod, which hinders the expansion and contraction of the piston rod, or the piston rod bites the bush and generates a sliding flaw on the surface of the piston rod to operate. May cause oil leaks. Also,
The lip of the oil seal provided inside the rod guide cannot be in close contact with the outer periphery of the piston rod, and the sealing performance of the oil seal may be impaired. These fears include motocross and ON-OFF, which are susceptible to external forces such as side forces.
Large in hydraulic shock absorbers such as cars.

An object of the present invention is to ensure the function of guiding the piston rod by the rod guide device and the function of sealing the damper cylinder even if the piston rod inserted into the damper cylinder of the hydraulic shock absorber is bent.

[0006]

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, and a damper cylinder is erected on one of the vehicle body side tube and the wheel side tube. A piston rod is erected on the other of the vehicle body side tube and the wheel side tube, and the piston rod is inserted into the damper cylinder while being supported by a rod guide device provided in an opening of the damper cylinder. In a hydraulic shock absorber in which a suspension spring is interposed between the tubes and an oil reservoir and a gas chamber are formed inside the vehicle body side tube and the wheel side tube, the rod guide device may be configured such that the inside of the opening of the damper cylinder is formed. A rod guide float-supported via a ring-shaped elastic sealing material on a support provided on the periphery, and a bush that is housed in the rod guide and guides the piston rod. Decorated the rod guide is obtained by the so and a oil seal for sealing the damper cylinder.

According to a second aspect of the present invention, in the first aspect of the present invention, the rod guide is further provided with a small gap in the axial direction with respect to a support provided on the inner periphery of the opening of the damper cylinder. Float supported.

[0008] The invention according to claim 3 is the invention according to claim 1 or 2.
In the invention described in (1), a cylinder head is sealed to an inner periphery of an opening of the damper cylinder, and the rod guide is float-supported on a support provided on the cylinder head.

According to a fourth aspect of the present invention, in addition to the third aspect, the cylinder head receives a rebound load when the piston rod is extended.

[0010]

According to the first aspect of the present invention, the following operations are provided. The rod guide constituting the rod guide device was float-supported on a support provided on the inner periphery of the opening of the damper cylinder via an annular elastic seal material. Therefore, when the hydraulic shock absorber receives an external force such as a side force and the piston rod bends, the rod guide follows the deflection of the piston rod and can be tilted or eccentric with respect to the center axis of the damper cylinder. For this reason, a large friction does not occur between the bush fixed to the rod guide and the piston rod to prevent expansion and contraction of the piston rod, and the piston rod bites the bush to generate a sliding flaw on the surface of the piston rod. It does not cause hydraulic oil leakage. Further, the lip of the oil seal provided inside the rod guide also keeps in close contact with the outer periphery of the piston rod, and does not impair the sealing performance of the oil seal.

According to the second aspect of the present invention, the following operations are provided. The rod guide can be reliably float-supported by providing the rod guide through a minute gap in the axial direction with respect to the support provided on the inner periphery of the opening of the damper cylinder.

According to the third aspect of the invention, the following effects are obtained. The cylinder head is sealed to the inner periphery of the opening of the damper cylinder, and the rod guide is float-supported on the support provided on this cylinder head, so the outer diameter of the rod guide can be reduced, and the rod guide can follow the piston rod. Can be improved.

According to the fourth aspect of the invention, the following effects are obtained. The rebound load at the time of the maximum extension of the hydraulic shock absorber is received by the cylinder head. Therefore, the function of guiding the piston rod by the rod guide device and the function of sealing the damper cylinder are not affected.

[0014]

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
2 is an enlarged sectional view of a main part of FIG. 2, and FIG. 6 is a sectional view showing a rod guide device.

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 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 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 rod guide device 80 provided on a cylinder head 70 screwed via an O-ring 71A to the inner periphery of the lower end opening of the damper cylinder 21 (lower cylinder tube 21B) as described later. It is inserted inside the cylinder 21. When the cylinder head 70 is screwed to the damper cylinder 21, the cylinder head 70 abuts against a spring seat 72 supported on a back surface by a stopper ring 72 </ b> A engaged with the inner periphery of the damper cylinder 21. The cylinder head 70
An oil lock collar 26 is provided on the outer peripheral portion of the outside. A rebound spring 27 is supported on the inner end surface of the cylinder head 70 via a spring seat 72. The free movement of the rebound spring 27 is restricted by a stopper ring 72B engaged with the inner periphery of the damper cylinder 21.

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. The partition member 33 includes a bush 37 that slides on the inner periphery of the wheel-side tube 12 and a plurality of elongated oil passages 33 </ b> A that allow the hydraulic oil in the oil reservoir 35 to flow up and down.

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 cylinder 1 abuts against a rebound spring 27 supported by a cylinder head 70 provided at an opening of the damper cylinder 21 to perform a buffering action for extension.

However, in the front fork 10, the rod guide device 80 provided at the opening of the damper cylinder 21 is configured as follows (FIGS. 5 and 6). As shown in FIGS. 1, 2, and 5, the front fork 10 has the cylinder head 70 sealed to the inner periphery of the opening of the damper cylinder 21 as described above, and is provided on the inner periphery of the cylinder head 70. The sub-assembly of the rod guide device 80 is assembled into the concave support portion 73, and the open end of the support portion 73 is closed by the above-mentioned spring seat 72.

At this time, the rod guide device 80 is
As shown in the figure, a small gap in the radial direction (the support portion 7 of the cylinder head 70) is formed by interposing an annular elastic seal material 81 such as an O-ring on the support portion 73 provided on the cylinder head 70.
When the inner diameter of the rod guide 3 is D1 and the outer diameter of the rod guide 82 is D2, the rod guide 82 is float-supported via D1> D2), and the piston rod is housed by being press-fitted into the inner diameter of the rod guide 82 or the like. A bush 83 that slides on and guides the piston rod 22;
The oil seal 84 is provided inside the second seal insertion portion 82A and closely adheres to the piston rod to seal the damper cylinder 21.
(Lip 84A). The rod guide 82 is integrally provided with a seal retainer 85 that presses the oil seal 84 into the seal insertion portion 82A and holds the oil seal 84 inside the seal insertion portion 82A while backing up the oil seal 84 with a backup ring 86. The rod guide device 80 supports the cylinder head 70 in a subassembly in which an elastic support member 81, a bush 83, a backup ring 86, and an oil seal 84 are attached to a rod guide 82 and a seal holder 85 is integrally provided. A small gap (the outer end face of the rod guide 82) is also provided in the axial direction between the back end face of the support part 73 of the cylinder head 70 and the spring seat 72 (depth L1 of the support part 73). When the length of the outer end surface of the seal retainer 85 is L2, it is stored so as to pass through L1> L2), and it is ensured that the rod guide 82 is float-supported by the support portion 73 of the cylinder head 70.

The rod guide 82 has a seal holder 85
When the flange 85A of the seal retainer 85 is brought into contact with the open end of the seal insertion portion 82A in the integrated state of the seal retainer 85 that presses the oil seal 84 at the distal end of the rod guide 82, the outer end surface of the rod guide 82 to the outer end surface of the seal retainer 85 Can be set to the above-mentioned L2.

Therefore, according to the present embodiment, the following operations are provided. A support portion 73 in which a rod guide 82 constituting the rod guide device 80 is provided on the inner periphery of the opening of the damper cylinder 21
Was supported by a float through an annular elastic seal material 81.
Therefore, when the front fork 10 receives the external force such as the side force and the piston rod 22 bends, the rod guide 82 follows the deflection of the piston rod 22 and can be tilted or eccentric with respect to the center axis of the damper cylinder 21. .
Therefore, a large friction does not occur between the bush 83 fixed to the rod guide 82 and the piston rod 22 to prevent the piston rod 22 from expanding and contracting. Also, there is no occurrence of sliding flaws to cause leakage of hydraulic oil. In addition, the lip of the oil seal 84 provided inside the rod guide 82 also keeps tightly contacting the outer periphery of the piston rod 22 and does not impair the sealing performance of the oil seal 84.

The rod guide 82 is connected to the damper cylinder 21
By providing a small clearance in the axial direction with respect to the support portion 73 provided on the inner circumference of the opening of the rod guide 8,
2 can be reliably float supported.

Since the cylinder head 70 is sealed on the inner periphery of the opening of the damper cylinder 21 and the rod guide 82 is float-supported on the support portion 73 provided on the cylinder head 70, the outer diameter of the rod guide 82 can be reduced. The followability of the rod guide 82 to the piston rod 22 can be improved.

The cylinder head 70 receives the rebound load when the front fork 10 is fully extended.
Therefore, the piston rod 2 by the rod guide device 80
The guide function of No. 2 and the sealing function of the damper cylinder 21 are not affected.

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.

[0046]

As described above, according to the present invention, even if the piston rod inserted into the damper cylinder of the hydraulic shock absorber is bent, the function of guiding the piston rod by the rod guide device and the function of sealing the damper cylinder are achieved. Can be secured.

[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 an enlarged sectional view of a main part of FIG. 2;

FIG. 6 is a sectional view showing a rod guide device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Front fork (hydraulic shock absorber) 11 Body side tube 12 Wheel side tube 13 Suspension spring 21 Damper cylinder 22 Piston rod 27 Rebound spring 35 Oil storage chamber 36 Gas chamber 70 Cylinder head 72 Spring seat 73 Support part 80 Rod guide device 81 Elasticity Seal material 82 Rod guide 83 Bush 84 Oil seal

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 one of the vehicle body side tube and the wheel side tube, and a piston rod is mounted on the other of the vehicle body side tube and the wheel side tube. The piston rod is inserted into the damper cylinder while being supported by a rod guide device provided at the opening of the damper cylinder, and a suspension spring is interposed between the vehicle body side tube and the wheel side tube, and In a hydraulic shock absorber having an oil reservoir and a gas chamber formed inside a tube and a wheel-side tube, the rod guide device includes a ring-shaped elastic sealing material provided on a support provided on an inner periphery of an opening of the damper cylinder. A rod guide that is float-supported through the bush, a bush that is housed in the rod guide to guide the piston rod, and a damper series that is housed in the rod guide. Hydraulic shock absorber characterized by comprising and an oil seal for sealing the dust. 2. The hydraulic shock absorber according to claim 1, wherein the rod guide is float-supported via a minute gap in an axial direction with respect to a support provided on an inner periphery of an opening of the damper cylinder. 3. The hydraulic shock absorber according to claim 1, wherein a cylinder head is sealed to an inner periphery of an opening of the damper cylinder, and the rod guide is float-supported on a support provided on the cylinder head. 4. The cylinder head receives a rebound load when the piston rod is extended.
The described hydraulic shock absorber.