JPS6118057B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a dual-tube shock absorber that separates oil and gas.

In general, in a dual-tube type gas-filled shock absorber that has an outer tube forming the gas chamber and an inner cylinder forming the oil chamber, if the oil chamber and gas chamber are not separated, the upper Gas enters through the oil hole in the bearing, and the seal becomes a gas shaft seal instead of an oil shaft seal, which makes it easy for gas to escape to the outside, resulting in disturbances in the damping force waveform.
Additionally, as the piston rod moves up and down, gas infiltrates into the cylinder from the guide of the bearing part, and oil and gas mix in the cylinder, creating an air ratio, which disrupts the damping force waveform and causes play in the operation, causing abnormal noise. It can also be the cause of For this reason, a hydraulic shock absorber as disclosed in, for example, Japanese Utility Model Publication No. 48-25495 is known as a method for solving this problem. In this type, a lip serving as a check valve is integrally formed in the seal portion to allow the flow of oil from the cylinder to the gas chamber, while blocking the flow of gas from the gas chamber to the cylinder. However, in such an oil chamber shock absorber, the piston rod, which is slidably installed inside the shock absorber, is constantly bent during operation, generating a twisting moment, and the lip provided integrally with the seal member needs to follow this movement. However, since the lip is provided integrally with the seal member, the movement is restricted by the lip,
As a result, twisting and the like occur, which not only deteriorates followability but also adversely affects durability and sealing performance. Furthermore, since the sealing member and the lip are integral, the lip and the sealing member must be made of the same material, and the position of the lip is determined by the relationship between the piston rod and the sealing member and cannot be adjusted. This has caused various problems such as insufficient check functions.

Therefore, the purpose of the present invention is to solve these conventional drawbacks by providing a double-tube shock absorber that separates oil and gas, which has significantly improved durability and followability of the check valve lip, and has improved check function. The goal is to provide the following.

To achieve this objective, the present invention has a structure including a cylinder filled with oil, an outer tube that defines a gas chamber on the outside of the cylinder, and an outer tube that is movably provided within the cylinder and that has a bearing and a seal at one end. A piston rod protrudes from the cylinder to the outside through a member, and a check valve mechanism that allows oil to flow only from the oil chamber in the cylinder toward the gas chamber between the gas chamber and the oil chamber in the cylinder. In the shock absorber provided with the check valve mechanism, the check valve body of the check valve mechanism is constituted by a member separate from the seal member, and the base end of the check valve body is fixed to the upper part of the bearing, and the other side of the check valve body is fixed to the upper part of the bearing. This is characterized in that the upper surface of the outer end can be moved into and out of the valve seat formed at the lower part of the seal member, and is held in a non-contact state with the piston rod.

Embodiments of the present invention will be described below with reference to the drawings.

In the figure, the shock absorber has a bearing 2 fixed to the upper end of a cylinder 1, a piston rod 3 is movably inserted into the center of the bearing 2, and an oil chamber 4 is defined within the cylinder 1.

A cover 5 is fixed above the bearing 2,
A piston rod 3 movably passes through the center of the cover 5, and an oil seal 6 as a sealing member is disposed inside the cover 5. The inner lip 7 of this oil seal 6 slides on the outer periphery of the piston rod 2 to prevent oil leakage. This also prevents dust from entering from the outside of the cover 5.

The base end of a check valve body 8 consisting of an elastic plate valve, which is a check valve mechanism constituted by an oil seal 6 and a member separate from the bearing 2, is fixed to the upper part of the bearing 2. The upper surface of the outer end contacts a valve seat 14 formed at the lower part of the oil seal 6 so as to be separable from the valve seat 14, and an oil chamber 9 is formed in the cover 5 by the check valve body 8, the oil seal 6, the bearing 2, and the piston rod 3. is formed.

The check valve body 8 is fixed to the bearing 2, and only its outer end contacts the valve seat 14 of the oil seal 6 so that it can be opened and closed, so the check valve body 8 itself is always maintained in a non-contact state with the piston rod 3. This means that it has been done.

Further, an outer tube 10 concentric with the cylinder 1 is fixed to the cover 5, and a gas chamber 11 is defined within the outer tube 10.
1 and oil chamber 4, gas and oil are separated. However, the lower part of the gas chamber 11 is filled with oil.

A through hole 12 is bored in the bearing 2, and the through hole 12 allows the oil chamber 9 and the gas chamber 11 to communicate with each other. In this case, since the check valve body 8 is disposed in contact with the valve seat 14 of the seal member 6, the gas from the gas chamber 11 acts in the direction of closing the check valve body 8, so that the oil chamber 9 is However, when the internal pressure of the oil chamber 9 increases, the outer end of the check valve body 8 is bent downward, and the oil in the oil chamber 9 flows out into the gas chamber 11 through the through hole 12, reaching the oil level below the gas chamber 11. Flow down.

That is, in the shock absorber of the present invention, oil in the oil chamber 4 leaks into the oil chamber 9 through the gap 13 between the bearing 2 and the piston rod 3 as the piston rod 3 slides, and this leaked oil temporarily flows into the oil chamber 9. However, since the check valve body 8 is flexible and comes into contact with the valve seat 14 at the bottom of the oil seal 6 under a slight set load, the oil stored in the oil chamber 9 does not fill up. When the internal pressure rises, the outer end of the check valve body 8 bends downward and opens, allowing oil in the oil chamber 9 to flow through the passage hole 12 into the gas chamber 11.

According to the present invention, the following effects are achieved.

In other words, since the check valve body is made up of a separate member from the seal member and is independent, even if a bending or twisting moment occurs in the seal member, the check valve body will not follow the movement of this seal member. Therefore, the check valve body does not need to be twisted.
The material of the check valve that is most suitable for performing the check function can be selected regardless of the material of the seal member, and the opening pressure can be freely controlled accordingly. The pressure applied to the seal can be optimally controlled by adjusting the increase in the amount of ejection from the gap with the piston rod and the decrease in rubber hardness due to high temperatures to changes in opening pressure. Since both the valve seat and the check valve body formed in the sealing member have elasticity, the sealing performance is good and there is no backflow of gas. Furthermore, by removing the check valve body, it is possible to easily configure it as a standard shock absorber that is not a gas-filled type. Since the check valve body is in a non-contact state with the piston rod, it is not affected by the vibrations of the piston rod and durability can be improved. The check valve body is assembled independently of the piston rod, allowing accurate positioning and easy assembly. Since there is nothing to prevent the outer end of the check valve body from bending downward, the response when opening is good.

[Brief explanation of the drawing]

The accompanying drawing is a partially cutaway vertical side view of a shock absorber according to an embodiment of the present invention. 1... Cylinder, 2... Bearing, 3... Piston rod, 6... Seal member, 7... Lip, 8... Check valve body, 9... Oil chamber, 10...
Outer tube, 11...gas chamber, 14...valve seat.

Claims (1)

[Claims] 1. A cylinder filled with oil, and an outer tube that defines a gas chamber on the outside of the cylinder;
A piston rod is movably provided in the cylinder and has one end protruding from the cylinder to the outside via a bearing and a seal member, and a piston rod is provided between the gas chamber and the oil chamber in the cylinder, and gas is supplied from the oil chamber in the cylinder. In a shock absorber equipped with a check valve mechanism that allows oil to flow only toward the chamber side, the check valve body of the check valve mechanism is constituted by a member separate from the seal member, and the check valve body of the check valve mechanism The base end of the check valve body is fixed to the upper part of the bearing, and the upper surface of the outer end of the check valve body can be moved to and from a valve seat formed at the lower part of the seal member, and is held in a non-contact state with the piston rod. A dual-tube shock absorber that separates gas.