JPH0424194Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] The present invention relates to a hydraulic shock absorber, and in particular, the arrangement structure of a so-called external type check seal inside a double-tube hydraulic shock absorber. This invention relates to an improved hydraulic shock absorber.

[Conventional technology]

As a structure for disposing a so-called external type check seal inside a dual-tube hydraulic shock absorber, there has been a proposal as shown in FIG. 2.

That is, the check seal 1 according to the conventionally proposed arrangement structure is arranged on the outer circumferential side of a rod guide 4 which is arranged at the upper end of the cylinder 2 and allows the piston rod 3 to be inserted into the axial center thereof. The lip portion 1a is adjacent to the inner periphery of an outer tube 6 which is disposed outside the cylinder 2 and whose upper inner periphery adjoins the lower end outer periphery of the seal case 5.

Therefore, the aerated hydraulic oil that may be generated in the upper chamber A of the cylinder 2 infiltrates the upper end side of the rod guide 4 when the piston rod 3 slides, and the rod guide 4 is perforated. When flowing into the upper end side of the check seal 1 through the drain groove 4a and the drain port 4b, the aerated hydraulic oil flows between the lip portion 1a of the check seal 1 and the outer tube 6 due to the increase in oil pressure. The liquid is returned to the outside of the cylinder 2 into the reservoir chamber B through the cylinder 2.

The aerated hydraulic oil once returned to the reservoir chamber B is prevented from flowing back from the check seal 1 portion due to the check function of the check seal 1.

[Problem that the invention attempts to solve]

However, in the arrangement structure of the check seal 1 described above, the heat generated when the seal case 5 is fixed to the upper end of the outer tube 6 by welding is transferred to the lip of the check seal 1 through the upper end of the outer tube 6. There is a risk that the check seal 1 will not be able to perform the desired check function in the hydraulic shock absorber as a final product due to the deterioration of the lip portion 1a.

Therefore, in view of the above-mentioned circumstances, the present invention has been developed to prevent the heat from being transmitted to the lip of the check seal even if heat is generated during welding when fixing the seal case to the upper end of the outer tube. The purpose is to provide a new hydraulic shock absorber.

[Means for solving problems]

In order to solve the above-mentioned problems, the hydraulic shock absorber according to the present invention has a structure that includes a rod guide that is disposed at the upper end of the cylinder and through which the piston rod is inserted through the shaft core, and a check seal that is disposed around the outer periphery of the rod guide. and a seal case fixed by welding to the upper end of the outer tube disposed outside the cylinder. The check seal is characterized in that lower end skirt portions are extended to face each other with a gap of , and the lip portion of the check seal is configured to come into contact with the inner periphery of the lower end skirt portion. .

[Effect]

Since the lip of the check seal is adjacent to the inner periphery of the lower end skirt of the seal case, the heat generated when the upper end of the seal case is welded to the upper end of the outer tube is not transmitted to the lower end skirt. This prevents the heat from being transferred to the lip of the check seal.

〔Example〕

Hereinafter, the present invention will be explained based on the illustrated embodiments.

As shown in FIG. 1, the hydraulic shock absorber according to the present invention is formed in a so-called double-tube type, and an outer tube 6 is disposed outside a cylinder 2, so that the cylinder 2 and the outer tube 6 are connected to each other. A reservoir chamber B is formed between the cylinders 2 and 2, and an upper chamber A is formed within the cylinder 2. And cylinder 2
The piston rod 3 inserted into the cylinder 2
It is inserted through the shaft core of a rod guide 4 arranged at the upper end, and a bearing 7 is arranged on the inner peripheral surface of the rod guide 4, and the piston rod 3 is in sliding contact with the bearing 7. .

A drain groove 4a is provided on the upper end surface of the rod guide 4.
A drain port 4b is formed on the outer circumferential side of the upper end, and when the piston rod 3 slides in and out of the cylinder 2, the rod guide 4 is drained from the upper chamber A through the space between the piston rod 3 and the bearing 7. Air-entrained hydraulic oil seeps into the upper end,
It flows out to the reservoir chamber B side below the outer circumferential side of the rod guide 4 through the drain groove 4a and drain port 4b.

A check seal 1 is disposed on the outer periphery of the intermediate portion of the rod guide 4, that is, on the outer periphery above the reservoir chamber B. The check seal 1 is arranged so that its rib portion 1a is on the outer circumferential side, and is formed to have a core bar 1b from the inner circumferential side to the upper end side. It is interposed in the rod guide 4 so that its peripheral side is in close contact with the outer peripheral side of the rod guide 4.

A seal case 5 is welded to the inside of the upper end of an outer tube 6 disposed outside the cylinder 2 . An oil seal 8 is housed on the inner periphery of the upper end of the seal case 5, and an oil lip portion 8a and a dust lip portion 8b of the oil seal 8 are in sliding contact with the outer peripheral surface of the piston rod 3, respectively. Further, a lower end skirt portion 5a is formed at the lower end side of the seal case 5, and the skirt portion 5a extends downward along the inner peripheral surface of the upper end side of the outer tube 6. In this embodiment, the outer circumferential surface of the skirt portion 5a is not in contact with the inner circumferential surface on the upper end side of the outer tube 6 that it faces, and an appropriate gap is formed there. The lip portion 1a of the check seal 1 is adjacent to the inner periphery of the skirt portion 5a.

Therefore, even if the heat generated when the seal case 5 is welded to the upper end of the outer tube 6 may be transmitted to the upper end side of the outer tube 6, it will not be transmitted to the lip portion 1a of the internal check seal 1. Further, the heat transmitted to the seal case 5 is absorbed by the thick main body portion on the upper end side of the seal case 25, so that the heat is not transmitted to the lower end skirt portion 5a, and the heat is absorbed by the check seal 1.
It is not transmitted to the lip portion 1a.

[Effect of idea]

As described above, according to the present invention, even if heat is generated when welding the seal case to the upper end of the outer tube, the heat is not transmitted to the lip of the check seal, and the hydraulic shock absorber as a final product is This has the advantage that the check function of the check seal on the device is not impaired.

Furthermore, according to the present invention, it is possible to store the check seal in advance inside the skirt at the lower end of the seal case, so when inserting the check seal into the inner side of the upper end of the outer tube of the seal case, the check seal is moved from the set position. It also has the advantage of eliminating inconveniences such as misalignment.

Furthermore, according to the present invention, even when the check seal needs to be replaced, by removing the seal case, the check seal can also be taken out to the outside, and the work can be done quickly. There are also advantages.

[Brief explanation of the drawing]

FIG. 1 is a partially enlarged cross-sectional view of a hydraulic shock absorber according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view similar to FIG. 1 of a conventional hydraulic shock absorber. 1...Check seal, 1a...Lip part, 2
... cylinder, 3 ... piston rod, 4 ... rod guide, 5 ... seal case, 5a ... lower end skirt section, 6 ... outer tube, A ... upper chamber, B ... reservoir chamber.

Claims (1)

[Scope of utility model registration request] A rod guide is installed at the upper end of the cylinder and allows the piston rod to pass through its axis, a check seal is installed around the outer periphery of the rod guide, and the upper end of an outer tube is installed outside the cylinder by welding. A seal case is fixed to the seal case, and a lower end skirt part extends from the lower end of the seal case to face the inner periphery of the upper end side of the outer tube with an appropriate gap. A hydraulic shock absorber characterized in that the lip portion of the check seal is configured to come into contact with the inner periphery of the lower end skirt portion.