JPH0128364Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an improvement of a dual-tube shock absorber having an oil chamber and a gas chamber.

In a double-tube shock absorber that uses both oil and pressure gas, a gas chamber is formed by placing a gas tube concentrically outside the hydraulic means consisting of a piston and an oil cylinder. Requires leakage prevention measures for gas.

FIG. 1 shows a conventional dual-tube shock absorber (Japanese Utility Model Application No. 54-53193) which is equipped with sealing means for pressure oil and pressure gas. That is, a small-diameter oil cylinder 1 and a large-diameter gas tube 2 are concentrically connected to each other to form a gas chamber 3 in the middle, and a piston (not shown) connected to the tip of a rod 4 connects the oil cylinder 1.
The rod 4 is arranged so as to be able to reciprocate in the axial direction.
A bearing 5 supporting the reciprocating motion of the gas tube 2 is fixed to the end of the oil cylinder 1 and cooperates with the oil cylinder 1 and the rod 4 to form an oil chamber 6. A packing cover 7 supported on the end of the gas tube 2 An oil seal 8 made of a rubber-like elastic material is disposed inside the bearing 5 to prevent oil leakage to the outside and external dust from entering the bearing 5 side. The attached check valve lip 10 is baked onto the washer 11 to approximately L.
A check valve 9 having a letter-shaped cross section is arranged adjacent to the oil seal 8, and the check valve lip 10 is brought into elastic contact with a conical peripheral surface 12 formed on the oil seal 8 side of the bearing 5. , an inner cavity 13 is formed on the rod 4 side, and an outer cavity 14 is formed on the packing cover 7 side, and a coil spring 15 that presses the check valve 9 toward the oil seal 8 side is located in the outer cavity 14. A communication hole 16 is provided near the outer periphery of the bearing 5 to connect the outer cavity 14 to the gas chamber 3 .

In the shock absorber having the above configuration, when the piston and the rod 4 rise, the pressure in the oil chamber 6 increases and a portion of the oil reaches the inner cavity 13 through the gap between the bearing 5 and the rod 4. is prevented from leaking to the outside by the oil seal 8, expands (opens) the check valve lip 10, flows into the outer cavity 14, and flows into the gas chamber 3 through the communication hole 16. When the piston and rod 4 descend, the pressure inside the oil chamber 6 decreases, but the check valve lip 10 touches the conical peripheral surface 12 of the bearing 5. Because of the pressure contact, the pressure gas in the gas chamber 3 and the outer space 14 is prevented from flowing into the inner space 13 side.

However, according to the above-mentioned shock absorber, since the oil seal 8 and the check valve 9 are supported by the coil spring 15, the sliding friction between the rod 4 and the oil seal 8 occurs, especially during the downward stroke of the rod 4. The behavior (position change) of the oil seal 8 that is pulled downward by the oil seal 8 affects the contact state between the check valve lip 10 and the circumferential surface 12 of the bearing 5, and the pressure on the gas chamber 3 side increases. There is a risk that gas may leak into the inner cavity 13, and furthermore, this pressure gas may leak out from the sealed sliding portion of the oil seal 8 and the rod 4.

The present invention was developed in view of the above points, and the inner circumferential annular tongue piece of a rubber-like elastic material formed in a substantially U-shaped cross section is used as the main lip that closely contacts the circumferential surface of the rod, and the outer circumferential annular tongue piece is The basic feature is that the oil seal is provided with a tongue piece as a check valve for opening and closing a communication hole of a reinforcing member provided on the inner circumferential side of the outer annular tongue piece, and the oil seal is sandwiched between a bearing and a gas tube. This is intended to strengthen the posture maintenance of the oil seal, and to ensure that pressure gas is sealed by the main lip and check valve lip.

An embodiment of the present invention will be described below with reference to FIG. 20 is an oil cylinder; 21 is a gas tube that is coaxially connected to the oil cylinder 20 to form a gas chamber 23 in the middle; 24 is a rod that has a piston (not shown) connected to its tip; A bearing 25 fixed to the shaft supports the rod 24 so as to be able to reciprocate in the axial direction. The outer peripheral surface of this bearing 25 is in contact with the gas tube 21 and has an appropriate number of communication grooves 26. The gas tube 21 has a radial portion 22 whose tip is bent in the inner radial direction. Reference numeral 27 denotes an oil chamber surrounded by the oil cylinder 20, rod 24, and bearing 25.

Reference numeral 28 denotes an oil seal consisting of a rubber-like elastic material 29 formed with a substantially U-shaped cross section, and a reinforcing member 32 with a substantially L-shaped cross section baked onto the rubber-like elastic material 29. The inner annular tongue piece of the elastic material 29 becomes a main lip 30 that comes into close contact with the circumferential surface of the rod 24, and the outer annular tongue piece becomes a check valve lip 31. The distal end surface of the axially extending portion of the reinforcing member 32 is in contact with the bearing 25, and an appropriate number of communication holes 33 are provided in the vicinity of this portion. The burning of the rubber-like elastic material 29 and the reinforcing member 32 is as follows.
This is done by leaving behind the annular band portion including the communication hole 33, and this non-scorched portion of the rubber-like elastic material 29 becomes the check valve lip 31. The oil seal 28 is held between the radial portion 22 of the gas tube 21 and the bearing 25.

In the shock absorber having the above configuration, when the rod 24 is on the upward stroke, the bearing 25
The oil leaking to the oil seal 28 side through the gap between the bearing 25 and the oil seal 24 is prevented from leaking outside by the main lip 30, accumulates in the cavity 34 between the bearing 25 and the oil seal 28, and is leaked through the communication hole 33. and reaches the check valve lip 31, and the check valve lip 31 is reached.
1 is expanded (opened), and the gas flows into the gas chamber 23 through the communication groove 26 (see Fig. 3), and the pressure in the chamber 34 and the oil chamber 27 decreases during the downward stroke of the rod 24. Since the check valve lip 31 is brought into pressure contact with the reinforcing member 32 by the pressure of the compressed gas, the communication hole 31 is closed, and the flow of the pressure gas toward the cavity 34 is prevented.

As explained above, the shock absorber of the present invention has an inner circumferential annular tongue made of a rubber-like elastic material formed into a substantially U-shaped cross section as the main lip that slides closely against the rod, and an outer circumferential annular tongue. It has an oil seal that serves as a check valve lip for the communication hole provided in the reinforcing member on the inner peripheral side of the outer peripheral tongue piece, and the oil seal is configured to be held between the bearing and the gas tube. The seal is firmly held, and there is no possibility that the sealing function of the main lip and check valve lip will be adversely affected by the reciprocating movement of the rod. In addition, a cavity is formed between the oil seal and the bearing, and this cavity functions as an oil reservoir, so that the bearing, main lip, and rod can slide closely together under good lubrication conditions. You will be able to do it. Furthermore, the product of the present invention can be constructed with fewer parts than conventional products, and can provide a shock absorber that not only has excellent retention and sealing properties as described above, but also has excellent durability and economical efficiency. Therefore, the practical effects of the present invention are extremely large.

[Brief explanation of the drawing]

The drawings show an embodiment of the shock absorber of the present invention, and FIG. 1 is a cross-sectional view showing an example of a shock absorber according to the prior art, and FIGS. 2 and 3 are cross-sectional views showing the shock absorber of the present invention. be. 1,20...oil cylinder, 2,21...gas tube, 3,23...gas chamber, 4,24...
Rod, 5, 25... Bearing, 6, 27...
Oil chamber, 8, 28...Oil seal, 10, 3
1... Check valve lip, 16, 33... Communication hole, 22... Radial direction portion, 26... Communication groove, 29
... Rubber-like elastic material, 30 ... Main lip, 32 ...
Reinforcement member, 34...vacant room.

Claims (1)

[Scope of utility model registration request] An oil cylinder and a gas tube are connected concentrically to each other to form a gas chamber in the middle, a piston and a rod are connected to each other and reciprocate within the oil cylinder, and the oil cylinder and the rod are fixed to an end of the oil cylinder. a bearing that cooperates with the rod to form an oil chamber and slidably supports the rod; The main lip slides closely against the main lip, and the outer circumferential annular tongue serves as a check valve lip that opens and closes the communication hole of the reinforcing member provided on the inner circumferential side of the outer circumferential annular tongue, and is sandwiched between the bearing and the gas tube. A shock absorber characterized by having an oil seal.