JPH025135Y2 - - Google Patents

Description

[Detailed explanation of the idea] This invention relates to a hydraulic shock absorber.

For example, various hydraulic shock absorbers are used in passenger cars to improve riding comfort. As an example of such a hydraulic shock absorber, as shown in FIG. 1, disc valves 3 and 4 are provided on both sides of a piston 2 that is slidably fitted into a cylinder 1 with communication holes 2a and 2b. It is known that this allows a damping force to be reliably generated even during continuous operation and high-speed operation.

However, in the case of such a conventional hydraulic shock absorber, during the extension stroke, the disc valve 4 separates from the seat surface 5 of the piston 2, and the fluid in the piston upper chamber 6 flows into the piston lower chamber 7, causing the piston 2 to flow into the lower chamber 7. The disc valve 3 comes into pressure contact with the seat surface 8, but as shown in FIG. 2, the disc valve 3 is bent at the annular groove 9 formed in the seat surface 8 due to back pressure, causing damage such as cracks to the disc valve 3. The drawback was that it lacked durability. In addition, in the contraction stroke of this hydraulic shock absorber, the number of plates constituting the disc valve 4 is large, and its overall rigidity is higher than that of the disc valve 3, so the above-mentioned damage is less; 4, the disc valve 3 separates from the seat surface 8 of the piston 2, and the fluid in the lower piston chamber 7 flows into the upper piston chamber 6, causing the disc valve 3 to separate from the seat surface 5 of the piston 2. The disc valve 4 was brought into pressure contact, and the disc valve 4, like the disc valve 3 during the extension stroke, was bent at the annular groove 10 part due to back pressure, and the disc valve 4 also had the drawback of being damaged such as cracking.

This idea was made in view of the above circumstances,
An annular groove is provided on both sides of a piston that defines two chambers in the cylinder, a communication hole is provided in the piston that communicates each of the annular grooves with the opposite side of the piston independently, and a communication hole is provided in the piston to cover each of the annular grooves and communicate with the opposite side of the piston. Disc valves are provided on both sides of the piston, the outer circumferential side of which can be bent in a direction away from the piston so as to open and close, and the inner circumferential side of which is fixed, and the disc valve is provided with a damping force for the extension stroke on one side of the piston,
In addition, in a hydraulic shock absorber in which the damping force of the compression stroke is generated by a disc valve provided on the other side of the piston, the back surface of at least one of the disc valves has a rigidity higher than the overall rigidity of the disc valve. A plate member having a plate member is disposed so as to be movable in the axial direction of the piston and cover the disc valve so that no back pressure is applied to the disc valve. prevent,
To provide a durable hydraulic shock absorber capable of preventing damage to a disc valve.

An embodiment of this invention will be described below with reference to FIGS. 3 to 5. Reference numeral 11 in FIG. 3 is a cylinder, and the cylinder 11 is composed of an outer cylinder 12, an inner cylinder 13, and a bottom cover 14 and a top cover 15 provided at the lower and upper ends of these cylinders, respectively. A reservoir 16 is provided between the outer cylinder 12 and the inner cylinder 13. This reservoir 16 is communicated with the inside of the inner cylinder 13 through a communication hole 17 provided at the lower part of the inner cylinder 13 . A mounting ring 18 is attached to the outer surface of the bottom cover 14, and a rod guide 19, a spring 20, a washer 21, and a seal member 22 are provided at the top of the cylinder 11.

A piston 23 is slidably fitted into the inner cylinder 13, and the center hole 24 of the piston 23 is fitted into a small diameter portion 26 formed at one end of a piston rod 25. It is attached to the piston rod 25 by a threaded nut 27. The other end of the piston rod 25 passes through the rod guide 19 at the top of the cylinder 11, the washer 21, and the seal member 22, and is connected to the cylinder 1.
1 stands out. As a result, inner cylinder 1
3 has a piston upper chamber 28 by the piston 23,
It is divided into a piston lower chamber 29. Oil is sealed in the piston upper chamber 28, piston lower chamber 29, and reservoir 16, and gas is sealed above the oil in the reservoir 16. A protection tube 30 is attached to the other end of the piston rod 25, and a mounting ring 31 is attached to the outer surface of this protection tube 30.

An annular groove 3 is provided on both end surfaces of the piston 23.
2 and 33 are formed. In addition, the piston 23
A communication hole 34 communicates with the annular groove 32 to communicate the piston upper chamber 28 and the piston lower chamber 29, and a communication hole 35 communicates with the annular groove 33 and communicates the piston lower chamber 29 and the piston upper chamber 28. is formed.

A disk valve 36 is provided on the piston upper chamber 28 side of the piston 23 to cover the annular groove 32 and open and close it. The disc valve 36 is made of two thin steel plates and is fitted into the small diameter portion 26.
Of the two plates of the disc valve 36, the plate on the piston 23 side has a concave cutout (not shown) extending in the radial direction of the plate.
A guide ring 37 is provided on the side opposite to the piston side of the disc valve 36 and is fitted into the small diameter portion 26 and serves as a fulcrum for the deflection of the disc valve 36. It is clamped and fixed between. Further, on the side opposite to the piston side of the disc valve 36, a plate member (annular plate) 38 having a rigidity higher than the overall rigidity of the disc valve 36 is disposed on a guide ring 37.
It is provided in a loose fit. Further, on the opposite side of the guide ring 37 from the piston side, an annular leaf spring 39 and a washer 40 are attached to the small diameter portion 26.
The spring 39 is fitted to the plate member 3.
8 is brought into pressure contact with the disc valve 36.
As a result, the disc valve 36 normally has an annular groove 3
2. It is brought into pressure contact with the seat surface 41 of the piston 23, covering the communication hole 34.

Further, a disc valve 42 is provided on the piston lower chamber 29 side of the piston 23 to cover the annular groove 33 and open and close it. The disc valve 42 is made of several thin steel plates and is fitted into the small diameter portion 26. The disk valve 42 is fitted with the small diameter portion 26 on the opposite side to the piston 23 side.
A retainer 43 is provided which serves as a fulcrum for the deflection of 2.
This retainer 43 is located on the inner peripheral side of the disc valve 42.
and the piston 23.
A washer 44 for preventing excessive deflection of the disc valve 42 and the nut 27 screwed onto the small diameter portion 26 are provided on the opposite side of the retainer 43 to the piston 23 side. disc valve 3
6, 42, etc. are attached. This results in
The disc valve 42 usually has an annular groove 33 and a communication hole 3.
5 and is brought into contact with the seat surface 45 of the piston 23. Note that the attachment rings 18 and 31 are attached to the wheels and the vehicle body, respectively.

Next, the operation of the hydraulic shock absorber having the above structure will be explained. In the case of an extension stroke in FIGS. 3 and 4, the piston 23 moves in the direction of arrow A in FIG. 4 relative to the cylinder 11 together with the piston rod 25 and the like. Then, the piston upper chamber 28
The oil inside flows into the piston lower chamber 29 through the notch and annular groove 32 formed on the piston 23 side of the disc valve 36, and the communication hole 34. At the same time, the oil in the reservoir 16 is pushed by the gas pressure above the reservoir 16 and flows into the lower piston chamber 29 through the communication hole 17. This generates a damping force during the extension stroke. After this, when the piston 23 continues to move in the direction of arrow A with respect to the cylinder 11, at a certain point the disc valve 42 is bent away from the piston 23 using the retainer 43 as a fulcrum, that is, toward the washer 44, and this causes the piston 23 to communicate with each other. Since the hole 35 is opened and the oil in the piston upper chamber 28 flows into the piston lower chamber 29 through the communication hole 35 and the annular groove 33, the oil can easily flow from the piston upper chamber 28 to the piston lower chamber 29. , the amount of increase in damping force decreases.

Note that during this extension stroke, back pressure is applied to the plate member 38, but since the rigidity of the plate member 38 is higher than the overall rigidity of the disc valve 36, the back pressure is applied to the disc valve 36 and the disc This prevents the valve 36 from bending.

On the other hand, in the case of the retraction stroke, the piston 23 moves in the direction of arrow B in FIG. 4 relative to the cylinder 11 together with the piston rod 25 and the like. Then, the oil in the piston lower chamber 29 flows into the piston upper chamber 28 through the communication hole 34 of the piston 23, the annular groove 32, and the notch formed on the piston 23 side of the disc valve 36, and at the same time, the oil in the piston The oil in the lower chamber 29 flows through the communication hole 17 to the reservoir 16.
flows into. This generates a damping force during the retraction stroke. Thereafter, as the piston 23 continues to move in the direction of arrow B relative to the cylinder 11, at a certain point the disc valve 36 resists the force of the spring 39 and moves away from the piston 23 using the guide ring 37 as a fulcrum, that is, toward the washer 40 side (the 4) and pushes the plate member 38 toward the washer 40. At this time, plate member 3
8 is loosely fitted to the guide ring 37 and therefore moves easily. As a result, the piston lower chamber 2
It becomes easier for oil to flow from 9 to the piston upper chamber 28,
The amount of increase in damping force during the compression stroke is reduced.
The damping force during the compression stroke can be changed by changing the spring constant of the spring 39. Also, during the extension stroke, back pressure is applied to the highly rigid plate member 38 to protect the disc valve 36, so the rigidity of the disc valve 36 can be lowered, so the spring constant of the spring 39 can be adjusted to an appropriate value. By setting this, the damping force during the compression stroke can be set to a low value regardless of the damping force during the extension stroke. Also, back pressure magnetism is applied to the disc valve 42 during the retraction stroke, but the disc valve 42 of this embodiment
Since it is composed of four sheets and has high overall rigidity, it will not be bent and damaged by back pressure.

In addition, in the above embodiment, the spring 39
is an annular leaf spring, but is not limited to this, for example, it may be a cruciform leaf spring having a center hole, or a plurality of coil springs located between the washer 40 and the plate member 38 and disposed in the circumferential direction. good.

Further, in the embodiment, a guide ring 37, a plate member 38, a spring 3, and a plate member 38 are used to prevent the disk valve 36 from being bent and damaged due to back pressure.
9, etc. are provided on the piston upper chamber 28 side of the piston 23, but the present invention is not limited to this, and the piston lower chamber 2
It can also be provided on the 9 side. This is because if the rigidity of the disc valve on the piston lower chamber 29 side is as low as the rigidity of the disc valve 36 on the piston upper chamber 28 side, the disc valve on the piston lower chamber 29 side will also be damaged by back pressure. Therefore, it is recommended to apply this in such cases.

Further, in the embodiment, the annular grooves 32, 3
Although the inner diameter of the plate member 38 is larger than the inner diameter of the plate member 38, the inner diameter of the plate member 38 is not limited to this.
If the rigidity of the plate member 38 is particularly high, the inner diameter of the plate member 38 may be made larger than the inner diameter of the annular grooves 32 and 33.

As explained above, according to this invention, annular grooves are provided on both sides of the piston defined in two chambers in the cylinder, and a communication hole is provided in the piston that communicates each of the annular grooves independently with the other side of the piston. established,
Disk valves are provided on both sides of the piston, the outer circumferential side of which is flexible in a direction away from the piston, and the inner circumferential side of which is fixed, so as to cover and open and close each of the annular grooves. In a hydraulic shock absorber, the damping force of the compression stroke is generated by a disc valve provided on the other side of the piston, and a damping force for the compression stroke is generated by a disc valve provided on the other side of the piston. A plate member with higher rigidity than the overall rigidity of the disc valve,
Since the piston is movable in the axial direction and is disposed over the disc valve so that no back pressure is applied to the disc valve, back pressure is applied to the disc valve and the disc valve is bent. Damage can be prevented by the plate member, thereby improving the durability of the disc valve, and by appropriately changing the rigidity or the number of disc valves, it is possible to improve the damping force during the extension stroke. The damping force during the retraction stroke can be changed or set to a low value regardless of the damping force during the retraction stroke, or the damping force during the extension stroke can be set to a low value regardless of the damping force during the retraction stroke, and the structure is simple with a small number of component parts. Therefore, it can be used by immediately attaching it to the piston part of the hydraulic shock absorber currently in use.

[Brief explanation of the drawing]

Figure 1 is a longitudinal sectional view of the main parts of a conventional hydraulic shock absorber.
Fig. 2 is a vertical sectional view showing the disk valve in a bent state due to back pressure, Fig. 3 is a longitudinal sectional front view showing an embodiment of this invention, and Fig. 4 is an enlarged sectional view of the circular part in Fig. 3. FIG. 5 is a partial sectional view showing the positional relationship of the disc valve, plate member, and spring during the retraction stroke. 11...Cylinder, 16...Reservoir, 17...
...Communication hole, 23... Piston, 25... Piston rod, 28... Piston upper chamber, 29... Piston lower chamber, 32, 33... Annular groove, 34, 35...
Communication hole, 36, 42... Disc valve, 37...
... Guide ring, 38 ... Plate member (annular plate), 3
9...Annular leaf spring (spring).

Claims (1)

[Claims for Utility Model Registration] (1) Annular grooves are provided on both sides of a piston that defines two chambers within the cylinder, and a communication hole is provided in the piston to communicate each of the annular grooves independently to the opposite side of the piston. Disc valves are provided on both sides of the piston, the outer circumferential side of which is flexible in a direction away from the piston, and the inner circumferential side of which is fixed, so as to cover each of the annular grooves and open and close the annular grooves. In a hydraulic shock absorber in which a disc valve provided on one side of the piston generates a damping force for the compression stroke, and a damping force for the compression stroke is generated by a disc valve provided on the other side of the piston, the rear surface of at least one of the disc valves. Further, a plate member having a rigidity higher than the overall rigidity of the disc valve is disposed so as to be movable in the axial direction of the piston and to cover the disc valve so that no back pressure is applied to the disc valve. Features a hydraulic shock absorber. (2) The hydraulic shock absorber according to claim 1, wherein the plate member is arranged so as to be brought into elastic contact with the back surface of the disc valve by a spring.