JPH0221626Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a hydraulic shock absorber used in automobiles and the like.

Generally, in this type of hydraulic shock absorber, the first
As shown in the figure, pressurized gas is sealed between a guide housing 2 disposed at one end 1a of a cylinder 1 filled with hydraulic fluid and the cylinder 1, surrounding the cylinder 1. A seal housing 5 disposed within one end 4a of the outer cylinder 4 forming the liquid reservoir chamber 3; and a slidable piston rod 6 extending into the cylinder 1 through the guide housing 2 and the seal housing 5. A piston 10 is provided with a damping force generating mechanism 9 fixed to the end 6a of the piston rod 6 to separate the inside of the cylinder 1 into two chambers, an upper liquid chamber 7 and a lower liquid chamber 8.
A dust seal member 11 and a fluid seal member 12 are provided at both ends of the seal housing 5 in the axial direction, respectively, and are in sliding contact with the outer peripheral surface of the piston rod 6. Further, 14 is a communication hole in the bottom body 13 provided at the bottom of the cylinder 1, which communicates the reservoir chamber 3 and the lower liquid chamber 8, and 15 is a cylindrical hole fixed to the portion of the guide housing 2 facing the piston rod 6. A bush 16 is a check valve made of an elastic material such as rubber, which is disposed in a recess 17 formed in the guide housing 2 facing the piston rod 6, and the tip of the check valve 16 comes into contact with the piston rod 6. It is formed like this. 20
21 is a liquid storage chamber formed above the guide housing 2 between the seal member 12 and the check valve 16, and 21 is a passage formed in the guide housing 2, communicating the reservoir chamber 3 and the liquid storage chamber 20. .

The hydraulic shock absorber having such a configuration operates as follows.

(1) In the case of the extension stroke of the piston rod 6 When the piston rod 6 rises, the piston 10 that follows it causes the upper liquid chamber 7 to have a high pressure, and conversely, the lower liquid chamber 8 to have a low pressure. At this time,
The high-pressure hydraulic fluid in the upper fluid chamber 7 flows through a through hole 9 that constitutes a damping force generating mechanism 9 provided in the piston 10.
a, and a plate valve 9 provided at its outlet end.
b is pushed open to form an orifice, and as the liquid passes through the orifice at high speed, the static pressure is changed to dynamic pressure, the pressure drops, and the liquid flows into the lower liquid chamber 8. Thus, the piston 10 is urged downward by the pressure in the upper liquid chamber 7, generating an extension-side damping force that attempts to prevent the extension stroke. At the same time, the hydraulic fluid corresponding to the piston rod withdrawal volume generated when a part of the piston rod 6 withdraws from the cylinder 1 flows from the reservoir chamber 3 into the lower liquid chamber 8 through the communication hole 14 provided at the bottom of the cylinder 1. will be compensated for. On the other hand, a part of the hydraulic fluid in the upper fluid chamber 7 flows into the fluid storage chamber 20 through the gap C1 between the piston rod 6 and the cylindrical bushing ₁₅ so as to widen the check valve 16. A passageway 21 that effectively lubricates the liquid seal member 12 and further extends through the guide housing.
The liquid flows into the reservoir chamber 3 and refluxes into the reservoir chamber 3.

(2) In the case of the pressure stroke of the piston rod 6 When the piston rod 6 descends, the lower liquid chamber 8 becomes high pressure due to the piston 10 moving therewith, and conversely, the upper liquid chamber 7 becomes low pressure, so the lower liquid chamber The hydraulic fluid in the damping force generating mechanism 9 passes through the through hole 9c and pushes open the plate valve 9d provided at the outlet end of the through hole 9c to form an orifice.
When passing through the orifice at high speed, static pressure is changed to dynamic pressure, the pressure drops, and the liquid flows into the upper liquid chamber 7. Thus, the pressure in the lower liquid chamber 8 causes the piston 10 to
is biased upward and generates a compression damping force that attempts to prevent the compression stroke. On the other hand, when a part of the piston rod 10 enters into the cylinder 1, the working fluid corresponding to the volume of the piston rod entering into the cylinder 1 returns from the lower fluid chamber 8 to the reservoir chamber 3 through the communication hole 14 at the bottom thereof, and enters the inside thereof. The pressurized gas sealed at a predetermined pressure is further compressed.

At this time, the pressurized gas in the reservoir chamber 3 is always in communication with the liquid storage chamber 20 through the passage 21, but is blocked by the close contact of the check valve 16 with the piston rod 6, and the upper part of the pressurized gas is The liquid is prevented from flowing into the liquid chamber 7.

However, in a hydraulic shock absorber having such a configuration, the contact angle at the contact portion 16a of the check valve 16 with respect to the piston rod 6 is such that the contact angle θ ₁ on the upper side is larger than that on the lower side as shown in FIG. The side contact angle is larger than θ ₂ . On the other hand, in the case of the pressure stroke of the piston rod 6, the pressure in the upper liquid chamber 7 becomes low, so that the pressure of the pressurized gas in the reservoir chamber 3 acting on the liquid retaining chamber 20 is increased as shown in FIG. In addition, the check valve 16 is brought into close contact with the piston rod 6, and the contact portion 16a is in partial surface contact.
If the liquid film is maintained without breaking on the surface of the piston rod 6 at this contact portion 16a, the friction at this portion will be reduced, but if the contact angle θ ₁ on the upper side is large, The liquid that should have adhered to the surface of the piston rod 6 and entered the abutting part 16a is scraped off at the upper part of the abutting part 16a, and is not sufficiently supplied to the abutting part 16a, preventing the formation of a liquid film. . Furthermore, when the lower contact angle θ ₂ is small, the contact portion 16a comes into tighter contact with the piston rod 6. In such a state, problems such as increased frictional resistance due to the sliding movement between the check valve 16 and the piston rod 6 and accelerated wear of the check valve 16 occur, resulting in damage to the hydraulic shock absorber. It has the disadvantage of malfunction or reduced lifespan and reliability.

This invention was made in view of the above, and
The purpose of this project is to obtain a hydraulic shock absorber that eliminates the drawbacks of the conventional ones.In order to achieve the above purpose, the shape of the check valve has been improved to reduce the frictional resistance with the piston rod, and the abutment area has been improved. The main objective is to reduce wear.

Embodiments of the present invention will be described below based on the drawings. That is, FIG. 4 shows the structure of a hydraulic shock absorber based on the present invention. Components that are the same as those of the conventional hydraulic shock absorber shown in FIG. 1 are given the same reference numerals, and redundant explanation thereof will be omitted. In the present invention, a recess 17 facing the piston rod 6 is formed in the upper end surface of the guide housing 2, and a check valve 22 made of an elastic member such as rubber is press-fitted into the recess 17. FIG. 5 shows an enlarged cross-sectional structure of this check valve 22.
That is, this check valve 22 has an outer peripheral portion 22a that is press-fitted into the liquid retaining chamber 20 formed in the guide housing 2.
A bottom portion 22b integrally provided radially inward from one end, an extending portion 22c extending upward from the inward side of this bottom portion 22b, and this extending portion 2.
The contact portion 22d is formed at the tip of the piston rod 2c and resiliently contacts the piston rod 6.
The contact angle at this contact portion 22d is characterized in that the upper contact angle θ ₄ is smaller than the lower contact angle θ ₃ of the contact portion.

Note that 23 is a reinforcing ring embedded in the check valve 22.

The operation of the check valve 22 will be explained below. First, in the case of the extension stroke of the piston rod 6, the pressure in the upper liquid chamber 7 shown in FIG. It flows through C ₁ to the liquid storage chamber 20 side while expanding the extending portion 22c of the check valve 22 in the diametrical direction as indicated by the broken line (FIG. 5). There, the liquid seal member 12 is lubricated, and the liquid further flows into the passage 21 and returns to the reservoir chamber 3.

Next, in the case of the pressure stroke of the piston rod 6, the pressure in the lower liquid chamber 8 becomes high, and the hydraulic fluid flows through the through hole 9c to the lower pressure upper liquid chamber 7, and at the same time, the hydraulic fluid corresponding to the intrusion volume of the piston rod is transferred to the lower part. Returns from the liquid chamber 8 to the reservoir chamber 3 through the communication hole 14 at the bottom,
The pressurized gas sealed inside at a predetermined pressure is further compressed. At this time, the hydraulic fluid stored in the fluid storage chamber 20 has the same pressure as the pressurized gas, and this pressure acts to push the check valve 22 toward the piston rod 6 side.

Therefore, the contact portion 22d is deformed as shown in FIG. 5. At this time, since the upper side contact angle θ ₄ is smaller than the lower side contact angle θ ₃ C, the contact portion 22
The close contact of the piston rod 6 with the piston rod 6 is relaxed, and the amount of hydraulic fluid adhering to the piston rod 6 that is scraped off at the upper end of the contact portion 22d is reduced. In this way, a sufficient liquid film can be formed on the surface of the piston rod 6 within the contact portion, reducing sliding resistance and preventing wear of the check valve 22.

FIG. 6 shows another embodiment of the present invention, in which the outer circumferential portion 22a of the check valve 22 is press-fitted into the recess 17 is positioned above the abutting portion 12a of the liquid sealing member 12 against the piston rod 6. It is characterized by being extended and formed to reach up to . With this configuration, the liquid storage chamber 20
The abutment part 12a of the liquid seal member 12 is constantly immersed in the hydraulic fluid stored in the interior, and the pressurized gas does not leak from this part, thereby improving the durability of the hydraulic shock absorber. You can improve your sexuality.

As explained in detail above, according to the present invention,
A check valve that forms a liquid retention chamber between the sealing member and seals the sealed gas pressure acting on the liquid retention chamber from inside the cylinder, is provided with a bottom portion and an extension portion extending upward from the bottom portion. , and a contact part formed at the tip of the extended part that contacts the piston rod, and the contact angle of this contact part with the piston rod is such that the contact angle on the upper side of the contact part is smaller than the contact angle on the lower side. This reduces the amount of working fluid scraped off the surface of the piston rod at the upper end of the abutment part even during the pressure stroke of the piston rod, so that a liquid film between the piston rod and the check valve is constantly maintained. This results in a state in which it is maintained. Therefore, an optimal contact state can be maintained while preventing an increase in frictional resistance, and material wear on the check valve side can be minimized, improving the life and reliability of the hydraulic shock absorber. This effect can be exerted, and it can be used in vehicles to bring about significant effects.

[Brief explanation of the drawing]

Fig. 1 is a partially omitted vertical sectional view showing a conventional hydraulic shock absorber, Fig. 2 is an enlarged sectional view showing the structure of the conventional check valve shown in Fig. 1, and Fig. 3 is the same as Fig. 2. 4 is a partially omitted longitudinal sectional view showing the structure of the hydraulic shock absorber based on the present invention, and FIG. 5 is a reverse sectional view of the check valve shown in FIG. 4. FIG. 6 is an enlarged sectional view of another embodiment of the check valve. 1...Cylinder, 2...Guide housing, 3
... Reservoir chamber, 4 ... Outer cylinder, 5 ... Seal housing, 6 ... Piston rod, 7 ... Upper liquid chamber, 8 ... Lower liquid chamber, 9 ... Damping force generation mechanism, 1
0... Piston, 11... Dust seal member, 1
2... Fluid seal member, 17... Recess, 20...
Liquid storage chamber, 21... passage, 22... check valve, 23...
Reinforcement ring.

Claims (1)

[Scope of utility model registration request] An outer cylinder is provided on the outer periphery of a cylinder filled with hydraulic fluid, and a hydraulic fluid reservoir chamber formed inside the cylinder by enclosing pressurized gas is communicated with the inside of the cylinder at its bottom. The piston rod is inserted through a guide housing provided at the upper end of the piston rod, and a seal member and a check valve that seal the piston rod are arranged in the axial direction on the upper side of the guide housing, and liquid is kept between them. A hydraulic buffer is formed by forming a chamber and communicating the liquid retaining chamber with a reservoir chamber, and sealing the sealed gas pressure acting on the liquid retaining chamber from the inside of the cylinder by the check valve. In the device, the check valve is composed of a bottom portion, an extending portion extending upward from the bottom portion, and an abutting portion formed at the tip of the extending portion and abutting the piston rod, and the abutting portion A hydraulic shock absorber characterized in that the contact angle with the piston rod is formed such that the contact angle on the upper side of the corresponding contact portion is smaller than the contact angle on the lower side.