JPH0221625Y2 - - 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 inside 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 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.

In view of the above points, the present invention was devised for the purpose of solving the problems seen in the above-mentioned prior art. a first oil seal that has a supporting bearing and a gas tube that is arranged on the outer peripheral side of the oil cylinder and has one axial end bent in the inner diameter direction, and that has a main lip that closely slides on the peripheral surface of the rod; and a second oil seal having a check valve lip that comes into elastic contact with the first oil seal, each of which is provided with a reinforcing member, and a portion of both of the reinforcing members are arranged in the axial direction so as to be in contact with each other. A reinforcing member is clamped between the bearing and the gas tube, and the outer cavity surrounded by both the oil seals is communicated with the gas chamber on the inner periphery of the gas tube.

In the shock absorber of the present invention having the above configuration, both the first oil seal provided with the main lip and the second oil seal provided with the check valve lip are firmly held between the bearing and the gas tube. The reinforcing member provided on the first oil seal stops the movement of the main lip, which deforms following the stroke operation of the rod, only on the main lip, supports the fixed part of the oil seal so that it does not move, and supports the fixed part of the oil seal so that it does not move. To prevent inconveniences such as a check valve lip, which comes into elastic contact with a portion, from opening by itself under the influence of the deformation.

The check valve lip constituting a type of check valve is formed into an annular shape, and it is desirable that the contact pressure against the other party with which it makes elastic contact is uniform over the entire circumference. In other words, if there is a weak contact pressure locally in the circumferential direction, when oil pressure acts from the rear as back pressure, only this weak contact pressure will separate from the mating material and open the valve. If this local opening and closing of the valve is repeated, there is a risk that material fatigue such as fatigue may occur only in that portion.
In contrast, the shock absorber of this invention has a second
A check valve lip provided on the first oil seal is arranged so as to be in elastic contact with the first oil seal, and a reinforcing member is provided on each of the two oil seals, and a portion of both the reinforcing members are brought into contact with each other. Since they are arranged in the axial direction,
Regardless of the assembly of the entire shock absorber, the contact pressure of the check valve lip can be set uniformly over the entire circumference simply by fitting both oil seals together. Both oil seals are clamped in series between the bearing and the gas tube. Therefore, it is sufficient to provide the gas tube constituting one of the clamping members with only one inner diameter bent portion.

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 and forms a gas chamber 23 in the middle, and 24 is a rod that has a piston (not shown) connected to its tip. It is supported by a bearing 25 fixed to the end of the shaft 20 so as to be able to reciprocate in the axial direction. The outer peripheral surface of the bearing 25 is in contact with the inner peripheral surface of the gas tube 21, and an appropriate number of communication grooves 26 are formed on the outer peripheral surface.
The tip of the gas tube 21 is bent in the inner radial direction to form a radial portion 22. 27 is the oil cylinder 20, the rod 24 and the bearing 25.
It is an oil chamber surrounded by.

Reference numeral 28 consists of a rubber-like elastic material 29 formed with a substantially U-shaped cross section, and a reinforcing member 30 with a substantially L-shaped cross section that is baked onto the inner wall surface of the rubber-like elastic material 29 along the annular recess. The first oil seal,
The annular tongue piece on the inner circumferential side serves as a main lip 33 that comes into close contact with the rod 24. Reference numeral 34 designates a second oil seal in which a rubber-like elastic material 39 is baked onto an axial portion 36 of a reinforcing member 35 having a substantially L-shaped cross section. An annular check valve lip 40 is integrally formed in elastic contact with the radial portion 31 of the reinforcing member 30 of the oil seal 28. Further, the first oil seal 2 is provided on the outer peripheral surface of this rubber-like elastic material 39 portion.
An annular ridge 41 in contact with the axial portion 32 of the reinforcing member 30 of No. 8 is integrally formed, and an appropriate number of communication grooves 42 are formed on the outer peripheral surface of the annular ridge 41. Further, an appropriate number of communicating notches 38 are formed in the radial portion 37 extending around the outer periphery of the reinforcing member 35 of the second oil seal 34 . The communication groove 26 formed in the bearing 25 and the communication groove 42 of this second oil seal 34
The communication notch 38 communicates the gas chamber 23 with an outer cavity 43 on the outer periphery of the check valve lip 40. 44 is an inner cavity surrounded by the first and second oil seals 28, 34 and the bearing 25. The first and second oil seals 28 and 34 are connected between the bearing 25 and the radial portion 22 of the gas tube 21 via the axial portion of the first oil seal 28 and the radial portion of the second oil seal 34. are clamped axially and in series.

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 first oil seal 28 through the gap between the main lip 33 and the rod 24 is prevented from leaking to the outside by the main lip 33, and the oil leaks into the inner cavity 44.
When the amount increases, the check valve lip 40 is pressed and expanded to flow out to the outer cavity 43, and the communication groove 42 and communication notch 38 of the second oil seal 34 as well as the communication groove 2 of the bearing 25 are
6 and then flows into the gas chamber 23 (see FIG. 3). Furthermore, during the downward stroke of the rod 24, the pressure in the inner chamber 44 and the oil chamber 27 decreases, but the check valve lip 40 is pressed by the pressure gas existing from the gas chamber 23 to the outer chamber 43. Since it is brought into pressure contact with the reinforcing member 30 of the first oil seal 28, the pressure gas is prevented from flowing to the inner cavity 44 side and further to the outside.

Also, the first and second oil seals 28, 34
is the radial part 2 of the gas tube 21 as shown in the figure.
2 and a bearing 25, and will not follow the reciprocating movement of the rod 24. As the rod 24 reciprocates, the main lip 33 of the first oil seal 28, which closely slides on the circumferential surface of the rod 24, is deformed, but this deformation is caused by the reinforcing member 30 attached to the fixed portion of the oil seal 28. By providing this, only the main lip 33 is deformed, and the check valve lip 40 is not affected. Check valve lip 4
The contact pressure with respect to the other side of 0 is both oil seals 2
8 and 34 are arranged so that the axial part 32 and the radial part 37 of the respective reinforcing members 30 and 35 are in direct contact with each other and are arranged in the axial direction.
It is set uniformly around the entire circumference. The gas tube 21, which is formed into a cylindrical shape as a whole, has two oil seals 28 and 34 arranged in series and clamped together between the gas tube 21 and the bearing 25. Not only can it be bent in the inner diameter direction to have a substantially L-shaped cross section, but it can also be easily processed.

As explained above, the present invention includes a first oil seal having a main lip that slides closely against the rod, and a check valve lip that comes into elastic contact with a reinforcing member of the first oil seal. 2
The main lip of the first oil seal and the second oil seal are sandwiched in series between the bearing and the gas tube. There is no possibility that the sealing function of the check valve lip of the oil seal will be adversely affected. As mentioned above, it is desirable for the check valve lip to set the contact pressure against the other party uniformly over the entire circumference, but the present invention is designed to set the check valve lip provided on the second oil seal to the first oil seal. This can be achieved simply by assembling both oil seals together by making them elastically in contact with the oil seals and arranging parts of the reinforcing members provided on both oil seals in the axial direction so as to contact each other. Also related to this, 2
Since we decided to sandwich two oil seals together between the bearing and the gas tube, the gas tube only needs to have one bent part on its inner diameter.
The shape of the gas tube can be simplified and its processing can be simplified. Further, since the cavity formed by the bearing and the first and second oil seals functions as an oil reservoir, the bearing, the main lip, and the rod can slide closely together under good lubrication conditions. Furthermore, the product of the present invention can be easily constructed with fewer parts than conventional products, and provides a shock absorber that not only has the above-mentioned excellent retention and sealing properties, but also 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. . 1,20...oil cylinder, 2,21...gas tube, 3,23...gas chamber, 4,24...
Rod, 5, 25... Bearing, 6, 27...
Oil chamber, 10, 40... Check valve lip, 13, 44... Inner cavity, 14, 43... Outer cavity, 22, 31, 37... Radial portion, 26,
42...Communication groove, 28...First oil seal,
29, 39... Rubber-like elastic material, 30, 35... Reinforcing member, 32, 36... Axial portion, 33... Main lip, 34... Second oil seal, 38... Communication notch, 41... ...Annular ridge.

Claims (1)

[Scope of utility model registration request] The rod 24 has a bearing 25 which is fixed to the oil cylinder 20 and supports the rod 24 in a reciprocating manner, and a gas tube 21 which is arranged on the outer peripheral side of the oil cylinder 20 and has one axial end bent in the inner radial direction. A first oil seal 28 with a main lip 33 that closely slides on the circumferential surface of the oil seal 28, and a second oil seal 34 with a check valve lip 40 in elastic contact with the first oil seal 28.
A reinforcing member 30, 35 is provided on each of the reinforcing members 30, 35, and parts of the reinforcing members 30, 35 are arranged in the axial direction so as to contact each other, and the reinforcing members 30, 35 are assembled between the bearing 25 and the gas tube 21 A shock absorber characterized in that the outer space 43 surrounded by the oil seals 28 and 34 is connected to the gas chamber 23 on the inner periphery of the gas tube 21.