JPH10231878A - Hydraulic shock absorber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make durability maintainable in a valve structure, so as to be optimum for mounting in a vehicle. SOLUTION: A peripheral side of a subvalve 3 is made adjacent capable of seating/unseating to an internal peripheral side seat part 2b formed in a lower surface of a piston 2, also a peripheral end of a main valve 4 is made adjacent capable of seating/unseating to a peripheral side seat part 2c formed in a lower surface of the piston 2, an annular groove 2e formed between the internal/external peripheral side seat parts 2b, 2c is made to communicate with a downward oil chamber R2 through a passage 2f formed in the peripheral side seat part 2c. With this communication, in a lower surface in a peripheral end of the main valve 4, a support 7 energized by a spring 6 from behind is made adjacent, the subvalve 3 has an opening 3d communicating with an extending side port 2a, on the other hand, the main valve 4 has an orifice 4b opposed to the opening 3d formed in the subvalve 3, also has a through hole 4a closed in a peripheral side of the subvalve 3, the orifice 4b is made to communicate with the through hole 4a through a receiving chamber R partitioned in an internal peripheral side of the support 7 between itself and the main valve 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a hydraulic shock absorber used for suppressing vehicle body vibration in a running vehicle mounted on a vehicle.

[0002]

2. Description of the Related Art There have conventionally been various proposals for a hydraulic shock absorber used for suppressing vehicle body vibration in a running vehicle mounted on a vehicle. For example, it is often proposed as an improvement of the valve structure for controlling the extension-side damping force in the piston portion.

[0003] In this case, the flow and amount of hydraulic oil acting on the valve are changed by driving an actuator externally attached to the hydraulic shock absorber or by operating a built-in position-dependent or frequency-dependent adjusting mechanism. Or to change the bending rigidity of the valve,
The overall complexity of the valve structure tends to increase the cost of the hydraulic shock absorber.

Therefore, a hydraulic shock absorber having a valve structure for generating a predetermined damping force while being assembled has been conventionally proposed.
The hydraulic shock absorber disclosed in Japanese Patent Publication No. 136 has the following valve structure.

That is, in the valve structure of the piston portion of the conventional hydraulic shock absorber, as shown in FIG. 6, the extension of the piston 2 slidably housed in the cylinder 1 is formed. On the downstream side of the side port 2a, two levels of valve seat surfaces having different height levels, that is, an inner seat portion 2b and an outer seat portion 2c are arranged in series, and each valve seat surface is The sub-valve 3 and the main valve 4, each of which is an annular leaf valve fixed at an inner peripheral end that opens with passage of hydraulic oil, are adjacent to each other.

The stamping orifice 2d is formed on the second-stage valve seat surface adjacent to the outer peripheral end of the main valve 4, that is, on the outer peripheral side seat portion 2c, so that the piston speed at which the flow rate of hydraulic oil is small is small. In the low speed range, the hydraulic oil from the extension side port 2a pushes only the sub-valve 3 open against the initial bending rigidity and passes through the stamping orifice 2d. It is said that the damping force will rise.

[0007] Further, in a low-speed region where the flow rate of the hydraulic oil increases, the hydraulic pressure in the annular groove 2e formed between the inner peripheral side seat portion 2b and the outer peripheral side seat portion 2c becomes main due to the throttle effect of the stamping orifice 2d. The initial flexural rigidity of the valve 4 will be exceeded.

As a result, after the low-speed range of the piston speed, the hydraulic oil from the expansion port 2a pushes the main valve 4 together with the sub-valve 3 to reduce the linear damping force having no orifice characteristics. Will be generated.

However, in the conventional hydraulic shock absorber shown in FIG. 6, the durability of the valve structure cannot be expected, and the intended suppression of the vehicle body vibration cannot be realized as set. There is concern.

That is, in the above-described conventional apparatus, since the spacer 5 is disposed between the sub-valve 3 and the main valve 4 in order to guarantee the bending of the sub-valve 3, when the piston speed becomes higher than the low speed range. The amount of deflection of the sub-valve 3 is extremely large compared to the amount of deflection when the piston speed is in a very low speed range.

Therefore, the so-called load acting on the sub-valve 3 is increased, and the sub-valve 3 is easily fatigued.
Therefore, the durability of the sub-valve 3, that is, the durability of the valve structure having the sub-valve 3 cannot be expected.

The present invention has been made in view of the above circumstances, and its object is to not only enable the suppression of vehicle body vibration, but also to maintain the durability of the valve structure. Another object of the present invention is to provide a hydraulic shock absorber which is optimal for mounting on a vehicle.

[0013]

In order to achieve the above object, the structure of the hydraulic shock absorber according to the present invention is such that a lower end opening of an extension side port formed in a piston for partitioning an upper oil chamber and a lower oil chamber is provided with a sub-valve. The main valve is disposed adjacent to the back of the sub-valve, and each valve is formed by an annular leaf valve, and is arranged in a manner that the inner peripheral end is fixed and the outer peripheral end is free. An outer peripheral end of the main valve is detachably adjacent to an inner peripheral seat portion formed on the lower surface, and an outer peripheral end of the main valve is detachably adjacent to an outer peripheral seat portion formed on the lower surface of the piston. The support urged by the spring from is adjacent to, and an annular groove formed between the inner peripheral side sheet portion and the outer peripheral side sheet portion is communicated with the lower oil chamber via a passage formed in the outer peripheral side sheet portion, Sub valve extends The main valve has an opening communicating with the port, the main valve has an orifice facing the opening formed in the sub-valve, and has a through hole closed on the outer peripheral side of the sub-valve, and the orifice communicates with the main valve on the inner peripheral side of the support. It is assumed that the sub-valve is communicated with the through-hole through a chamber partitioned between the sub-valves and the outer peripheral end of the sub-valve is present in the annular groove.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described based on one embodiment shown in the drawings. As shown in FIG.
Even in the hydraulic shock absorber according to one embodiment of the present invention,
An extension port 2 formed in a piston 2 slidably housed in a cylinder 1 and defining an upper oil chamber R1 and a lower oil chamber R2.
a has a sub-valve 3 composed of an annular leaf valve for closing the lower end opening so as to be openable, and has a main valve 4 composed of an annular leaf valve.

However, in this embodiment, the main valve 4 is assumed to be adjacent to the lower surface of the sub-valve 3, and as long as the main valve 4 is located between the main valve 4 and the sub-valve 3 as in the conventional example shown in FIG. The mode in which the seat 5 is interposed is not set.

Therefore, in the case of this embodiment, it is a matter of course that there is an advantage that a part called the spacer 5 becomes unnecessary, but the amount of bending of the sub-valve 3 is reduced.
Is no more than the amount of deflection of the main valve 4, so that it is backed up, so to speak,
It can be said that the durability of the sub-valve 3 can be expected to continue without unnecessarily reducing the durability of the sub-valve 3 as compared with the above-described conventional example.

On the other hand, the configuration of each of the valves 3 and 4 is as follows. While each of the valves 3 and 4 in the above-described conventional example is a simple annular leaf valve, according to this embodiment, It has such a configuration.

That is, first, as shown in FIG. 2, the sub-valve 3 is formed in a fixed portion 3a on the inner peripheral side formed in an annular shape.
And a connecting portion 3c for connecting the operating portion 3b to the fixed portion 3a, and a C-shaped opening 3d formed as a result. Have.

When the sub-valve 3 is disposed in a predetermined state, as shown in FIG.
d is made to face the lower end opening of the extension side port 2a so as to communicate therewith.

Next, as shown in FIG. 2, the main valve 4 is concealed from above by an operating portion 3b of the sub-valve 3 in a ring-shaped main body (not shown) having a larger diameter than the sub-valve 3. A plurality of through holes 4a are provided at appropriate intervals (six in the illustrated example), and a plurality of orifices 4b facing each other so as to be exposed at the opening 3d of the sub-valve 3 are provided at appropriate intervals (three in the illustrated example). ) Have.

Each of the valves 3 and 4 formed as described above
Are fixed to the inner peripheral end and are arranged in a manner that the outer peripheral end is free, and as long as it is the same as the conventional example described above, the sub-valve 3 has a piston on the outer peripheral side in the illustrated embodiment. An inner peripheral seat portion 2b formed on the lower surface of the seat 2 is detachably adjacent to the seat portion 2b.

The main valve 4 has an outer peripheral end removably adjacent to the outer peripheral side seat portion 2c formed on the lower surface of the piston 2 and a support biased by a spring 6 from behind on the lower surface of the outer peripheral end. 7 are adjacent.

At this time, the support 7 defines a chamber R on the inner peripheral side thereof between the support 7 and the main valve 4, and the communication between the orifice 4b and the through hole 4a through the chamber R is established. Accept.

A passage 2f formed by an embossing groove is formed in the outer peripheral sheet portion 2c, and an annular groove 2e formed between the inner peripheral sheet portion 2b and the outer peripheral sheet portion 2c is formed in the passage 2f. The lower end of the sub-valve 3 is communicated with the lower oil chamber R2 via an annular groove 2e.

Although not shown, the passage 2f formed by the embossed groove in the outer peripheral side seat portion 2c may be formed by a notched groove formed in the outer peripheral end of the main valve 4. In this case, a predetermined groove is formed. This is advantageous in that the formation of the passage is simpler than forming the embossed groove in the piston 2.

Incidentally, the lower end of the spring 6 is screwed to a lower thread (not shown) of the piston rod 8 and the upper end is provided with the spacer 9 so that the inner peripheral end of the main valve 4 is inserted into the sub-valve 3. The piston 2 is carried by a piston nut 10 sandwiched between the peripheral end and the lower surface of the inner peripheral end of the piston 2.
The upper end opening of the pressure-side port 2g formed by the non-return valve 11 is closed and opened.

In the hydraulic shock absorber according to this embodiment formed as described above, a predetermined damping action is performed as follows during the extension stroke in which the piston 2 rises in the cylinder 1. Become.

First, when the piston speed is very low,
As shown by an arrow a in FIG. 3, the hydraulic oil from the expansion side port 2a formed in the piston 2 reaches the pressure receiving surface side of the sub-valve 3, and the opening 3d formed in the sub-valve 3 and the main valve exposed to the opening 3d. 4 flows into a chamber R formed on the back side of the main valve 4 via an orifice 4b formed in the main valve 4.

The hydraulic oil from the chamber R is bent through the through hole 4a formed in the main valve 4 and lifts the outer peripheral end of the sub-valve 3 upward with the inner peripheral side seat portion 2b as a fulcrum. And flows into the annular groove 2e.

The hydraulic oil that has flowed into the annular groove 2e flows out to the lower oil chamber R2 via the passage 2f formed in the outer peripheral side seat portion 2c. A predetermined extension-side damping force is generated by upward bending of the outer peripheral end of the sub-valve 3 with the side seat portion 2b as a fulcrum.

On the other hand, when the piston speed becomes higher than the low speed,
As shown by an arrow b in FIG. 4, the hydraulic oil from the extension side port 2a formed in the piston 2 cannot pass through the orifice 4b exposed to the opening 3d of the sub-valve 3, and the outer side of the sub-valve 3 is moved to the inner side. It will be bent so as to separate from the seat portion 2b.

At this time, since the sub-valve 3 is disposed next to the main valve 4 in a so-called stacked state, the sub-valve 3
The hydraulic oil that bends the outer peripheral end of the main valve 4 deflects the outer peripheral end of the main valve 4 downward so as to push down the support 7 urged by the spring 8.
Therefore, a predetermined extension side damping force is generated by the bending operation of the outer peripheral end of the main valve 4.

As a result, in this embodiment, the damping force of the valve characteristics by the sub-valve 3 can be expected in a very low speed region of the piston speed, and the damping force of the valve characteristics by the main valve 4 when the piston speed becomes higher than the low speed region. This can be expected.

In this embodiment, the sub-valve 3 performs a damping action by bending the outer peripheral end upward at a very low piston speed range, and also deflects the sub-valve 3 at a lower piston speed range. But the main valve 4
By bending the outer peripheral end downward, a damping action is performed.

When this damping effect is compared with the above-described conventional case, the conventional case is a damping force effect in a state where the valves 3 and 4 are arranged in series. In this case, the difference is that a damping force is exerted when the valves 3 and 4 are arranged in parallel.

As a result, for example, as shown in FIG.
Assuming that the characteristic shown by the phantom line is the case of the conventional hydraulic shock absorber shown in FIG. 6, if the rise of the damping force in a very low speed region of the piston speed is to be improved as shown by the characteristic shown by the broken line, The damping force above the low speed range becomes abnormally high, and even if the steering stability is improved, the riding comfort is extremely deteriorated.

On the other hand, according to this embodiment, since the valves 3 and 4 are arranged in parallel and their generated damping forces can be set independently, the damping force in a very low piston speed range is reduced. Even if it is set to improve the rise,
There is no danger of abnormally high damping force at piston speeds above the low speed range.This improves steering stability when the piston speed is in the very low speed range, and improves ride comfort when the piston speed is above the low speed range. Improvements will also be possible.

Although the above description has been made by taking as an example the case where each of the valves 3 and 4 is disposed on the piston 2 in the cylinder 1, it is not shown from the viewpoint of the present invention. However, each of the valves 3 and 4 may be disposed in the base valve section in the cylinder 1 and used for controlling the compression-side damping force. Of course, the operation and effect in this case are not different.

[0039]

As described above, according to the present invention, when the piston speed is in a very low speed range, the outer peripheral end of the sub-valve bends upward without interfering with the main valve. The sub-valve will bend downward together with the main valve, so long as the sub-valve is backed up by the main valve on the back side, and therefore, the sub-valve will not bend more than the amount of deflection of the main valve. Therefore, the durability of the sub-valve can be expected.

According to the present invention, the sub-valve acts to deflect the outer peripheral end upward in a very low speed range of the piston speed, and lowers the outer peripheral end of the main valve below the low speed range of the piston speed. Since the damping action is performed by bending the valve, the damping action is compared with the conventional case, whereas the conventional case is the damping force action in a state where the respective valves are arranged in series. The damping force acts when the valves are arranged in parallel.

As a result, it is possible to independently set the respective damping forces generated by the sub-valve and the main valve. In particular, while improving the rise of the damping force in a very low speed range and improving the steering stability, Above the low-speed range of the piston speed, it is possible to improve the riding comfort while suppressing the overall low damping force.

Further, in the present invention, since the operating range of each valve is limited, the durability of each valve can be expected as set, and therefore, the durability of each valve is maintained. The durability of the entire valve structure can be maintained.

As a result, according to the present invention, it is possible to expect the generation of a preferable damping force while suppressing the body vibration while maintaining the durability of the valve structure.
There is an advantage that it is optimal for mounting on a vehicle.

[Brief description of the drawings]

FIG. 1 is a partial longitudinal sectional view showing a structure of a piston part in a hydraulic shock absorber according to the present invention.

FIG. 2 is a plan view showing a laminated sub-valve and a main valve arranged in a piston portion.

FIG. 3 is a partially enlarged longitudinal sectional view showing an operation state of a sub-valve in a piston portion in FIG.

FIG. 4 is a view showing an operation state of a sub-valve and a main valve in a piston portion in FIG. 1, similarly to FIG.

FIG. 5 is a diagram showing characteristics of the extension damping force with respect to the piston speed by the hydraulic shock absorber of FIG. 1 in comparison with the characteristics of a conventional hydraulic shock absorber.

FIG. 6 is a view showing a structure of a piston portion in a hydraulic shock absorber as a conventional example, similarly to FIG.

[Explanation of symbols]

 2 Piston 2a Expansion port 2b Inner peripheral seat 2c Outer peripheral seat 2e Annular groove 2f Passage 3 Sub-valve 3d Opening 4 Main valve 4a Through hole 4b Orifice 6 Spring 7 Support R Storage chamber R1 Upper oil chamber R2 Lower oil chamber

Claims (1)

[Claims] 1. A lower valve opening formed in a piston that defines an upper oil chamber and a lower oil chamber is openably closed by a sub-valve, and a main valve is provided adjacent to a back surface of the sub-valve.
Each valve is formed by an annular leaf valve and is arranged in a manner such that the inner peripheral end is fixed and the outer peripheral end is free, and the outer peripheral side of the sub-valve is detachably adjoined to the inner peripheral side seat portion formed on the lower surface of the piston, and the The outer peripheral end of the valve is removably adjacent to the outer peripheral seat formed on the lower surface of the piston, and a support biased by a spring from behind is adjacent to the lower surface of the outer peripheral end of the main valve. An annular groove formed between the outer peripheral side seat portion and the outer peripheral side seat portion communicates with the lower oil chamber through a passage formed in the outer peripheral side seat portion, and the sub valve has an opening communicating with the extension side port, and the main valve is connected to the sub valve. It has an orifice facing the opening of the formation and has a through-hole closed on the outer peripheral side of the sub-valve, and the orifice communicates with the through-hole via a chamber defined between the main valve on the inner peripheral side of the support. It is, and hydraulic shock absorber outer peripheral end of the sub-valve is formed by His presence in an annular groove