JPH0356669Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an improvement of a damping force generating device for a hydraulic shock absorber used in a rear suspension unit of a two-wheeled vehicle.

[Conventional technology]

The damping force generated in a rear action unit of a two-wheeled vehicle is set so that the damping force in a piston high speed range is significantly larger than that in a low speed range in a normal proportional valve.

However, for the reaction unit,
For example, when braking from high-speed driving on a straight course, when the rear side begins to extend in response to the front side sinking due to braking, if the damping force generated on the rebound side in the piston high-speed range is high, the rear suspension unit may not extend enough. The drawback was that the tire's ability to follow the road surface deteriorated, resulting in a decrease in ground contact force. For this reason, the present applicant has developed a damping force generating device that relatively reduces the rebound damping force in the piston high speed range, as shown in FIG.

A piston 2 is housed in a cylinder part 1 so as to be able to slide freely, oil chambers are defined above and below the piston, and a first leaf valve 11 whose outer periphery contacts the seat part of the piston, and a first leaf valve 11 located below the piston 2 are provided with oil chambers above and below the piston. The diameter is smaller than that and the first
A second leaf valve 13 is provided to close an orifice 12 formed in the leaf valve, and a main valve 15 is further provided opposite to the first leaf valve and urged toward the closing side via a spring 14. be.

By doing this, in the extension stroke of the piston 2, in the low piston speed range, the hydraulic oil flowing through the piston passage is transferred to the second leaf valve 1.
3 passes through the orifice 12 while deflecting, and generates a damping force according to the amount of deflection of the second leaf valve 13. In the medium speed range of the piston, the second leaf valve 13 hits the main valve 15 and the deflection is reduced. When the damping force is regulated, the generated damping force is the same as when flowing through a constant orifice, and furthermore, in the high piston speed range, as shown in Fig. 4, the damping force generated is the same as when flowing through a constant orifice.
The leaf valve 11 overcomes the spring load of the main valve 15 and pushes up the main valve 15, and a damping force is generated by the main valve 11.

[Problem that the invention attempts to solve]

However, in the above damping force generating device, as shown in FIG. It is only
The outer end is extremely flexible. For this reason, excessive stress is generated near the shim supporting the second leaf valve 13, causing problems such as cracking or deformation of the second leaf valve 13.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a damping force generating device for a hydraulic shock absorber which improves the conventional device and prevents the second leaf valve from cracking or deforming.

[Means for solving problems]

In order to achieve the above object, the configuration of the present invention is characterized in that a second leaf valve is provided opposite to the first leaf valve so as to be movable up and down.

[Effect]

In the high speed range of the piston, even when the first leaf valve is deflected, the second leaf valve can be lowered entirely, and excessive deflection does not occur.

In FIG. 1, a piston 2 is slidably housed in a cylinder portion 1 and is fixed to a piston rod 3 via a lock nut 4. As shown in FIG.

The piston 2 is formed with a passage 5 through which hydraulic oil flows during compression side operation and a passage 6 through which hydraulic oil flows during rebound side operation. A compression side valve 7 that opens the compression side passage 5 to generate a predetermined damping force during compression side operation, and a growth side valve 8 that opens the expansion side passage 6 and generates a predetermined damping force during expansion side operation are provided.

Here, the expansion side valve 8 has a piston seat portion 10
a first leaf valve 11 whose outer peripheral portion is in contact with the first leaf valve 11;
A second leaf valve 1 which has a smaller diameter than the first leaf valve 11 and closes the orifice 12 provided in the first leaf valve 11 from the lower back surface.
3 and the first leaf valve 11 with a spring 14
The main valve 15 is biased toward the closing side via the main valve 15.

In the above configuration, the outer periphery of the second leaf valve 13 is supported by the main valve 15. That is, the spacer 19 is supported on the main valve 15, and the second leaf valve 13 is supported on the spacer 19.
The outer peripheral lower surface of the first leaf valve 11 is brought into contact with the outer peripheral lower surface of the first leaf valve 11, and the upper surface thereof is brought into contact with the outer peripheral lower surface of the first leaf valve 11. There is a gap equal to the thickness of the spacer 19 between the inner circumference side of the second leaf valve 13 and the main valve 15, so that the inner circumference of the second leaf valve 13 can be bent downward.

The first leaf valve 11 is crimped and fixed at its center to the piston 2 by the lock nut 4 and the shim 20. Also, the main valve 15 is a lock nut 4.
A spring 14 is slidably disposed on the outer periphery of the first leaf valve 11 and is inserted between the spring guide 16 and the first leaf valve 11 from the back side of the seat part 1.
Press so that it comes into pressure contact with 0. Main valve 15
is provided with an orifice 17, and the hydraulic oil that has passed through the orifice 12 of the first leaf valve 11 further passes through this orifice 17.

The spring guide 16 is fixed to a push rod 18 passing through the piston rod 3, and by adjusting the position of the push rod 18 from the outside, the spring load on the main valve 15 can be increased or decreased.

The device is configured as described above, and its operation will be explained next.

During the extension stroke of the piston 2, in the low piston speed range, the inner side of the second leaf valve 13, which is the weakest, is deflected due to the hydraulic oil flowing through the through hole 22 provided in the valve stopper 21 and the extension passage 6.
It passes from the orifice 12 of the first leaf valve 11 to the orifice 17 of the main valve 15 . In this state, a damping force corresponding to the amount of deflection of the second leaf valve 13 is generated, similar to the so-called Girling type valve.

In the medium speed range of the piston speed, the inside of the second leaf valve 13 comes into contact with the inside of the main valve 15 and is regulated by deflection, and the damping force is exerted by the orifice 12,
This corresponds to the flow path resistance when passing through 17.

When the piston speed further increases and reaches a high speed range, the outside of the first leaf valve 11 begins to bend against the spring 14 of the main valve 15, as shown in FIG. At this time, the first leaf valve 11 lowers the main valve 15 via the second leaf valve 13 and the spacer 19. At this time, compared to the flow rate flowing through the orifices 12 and 17,
Since the flow rate from the first leaf valve 11 is much larger, the damping force generated after the first leaf valve 11 starts to open has a characteristic that increases gradually.

Describing the relationship between these damping forces, the increasing curve of the damping force is gradual from the low piston speed range to the high speed range, and therefore the damping force in the maximum piston speed range can be relatively reduced. Therefore, when braking from high-speed driving, for example, the rear suspension unit can smoothly extend as the front side sinks, and the ground contact of the rear wheels can be improved.

By the way, during the bending operation of the main valve 11, the second leaf valve 13 is in a state where the inside is bent and the outside is supported by the main valve 15 via the spacer 19, and is not in line with the main valve 15. Since the second leaf valve 13 descends in a series, excessive stress is not applied to the part supported by the spacer 19, and therefore, the second leaf valve 13 is not subjected to excessive deflection, and its deformation, cracks, cracks, etc. Does not occur.

By changing the initial load of the spring 14 of the main valve 15 by moving the push rod 18 back and forth, the damping force generated in the high speed range can be adjusted.

2 and 3 relate to other embodiments of the present invention,
This supports the base end of the inner periphery of the second leaf valve 13 so as to be movable up and down. Other configurations,
The effect is the same as the embodiment of FIG.

That is, a valve guide 24 that also serves as a spacer for supporting the base end of the first leaf valve 11 is provided at the upper end of the lock nut 4, and the inner peripheral base end of the second leaf valve 13 and the support 23 are provided on the outer periphery of this valve guide 24. The proximal end of is supported so as to be movable up and down.

A gap 25 corresponding to an arbitrary width h is formed between the lower surface of the support 23 and the upper end of the lock nut 4, and the second leaf valve 13 can be lowered together with the support 23 by the distance of this gap 25. There is.

Therefore, in a low speed range, the first leaf valve 11 is bent downward by an amount corresponding to the thickness of the support 23, and in a high speed range, the outer periphery of the first leaf valve 11 is also bent while pushing down the main valve 15. However, as shown in Figure 3, at this time the second
The entire leaf valve 13 is lowered by the width h while being supported by the support 23, and no excessive deflection occurs. Therefore, deformation, cracking, cracking, etc. are prevented.

[Effect of idea]

As described above, according to the present invention, since the second leaf valve is movable up and down, excessive deflection does not occur, and deformation, cracking, cracking, etc. are prevented, and the expansion of the piston in the high speed range is prevented. This has the effect of making it possible to relatively reduce the side damping force, improve the return of the tire to the road surface when the rear suspension unit starts to extend, increase the ground contact force, and improve steering stability.

[Brief explanation of the drawing]

1 and 2 are cross-sectional views of each embodiment of the present invention,
3 is an explanatory diagram of the operation of FIG. 2, and FIG. 4 is a sectional view of a conventional hydraulic shock absorber. 1...Cylinder part, 2...Piston part, 3...
Piston rod, 5, 6... Passage, 7... Compression side valve, 8... Rebound side valve, 10... Seat part, 1
1...first leaf valve, 12...orifice,
13...Second leaf valve, 14...Spring, 15...Main valve, 18...Push rod, 23...Support, 25...Gap, h...
Width, 17...orifice.

Claims (1)

[Scope of claims for utility model registration] (1) A piston is housed in the cylinder so that it can slide freely,
In a hydraulic shock absorber in which oil chambers are defined above and below a piston, a first leaf valve whose outer periphery is in contact with the seat portion of the piston is provided, and a first leaf valve having a smaller diameter than the first leaf valve is provided below the first leaf valve. The second valve closes the orifice formed in the leaf valve.
1. A damping force generating device for a hydraulic shock absorber, characterized in that a leaf valve is provided which is movable up and down, and a main valve is provided facing the first leaf valve to urge it toward the closing side via a spring. (2) The damping force generating device for a hydraulic shock absorber according to claim 1, wherein the outside of the second leaf valve is supported by the main valve and can be lowered together with the main valve. (3) The damping force generating device for a hydraulic shock absorber according to claim 1, wherein the inner base end of the second leaf valve is supported so as to be movable up and down.