JP2870678B2 - Hydraulic shock absorber - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic shock absorber incorporating an oil seal.

[0002]

2. Description of the Related Art Japanese Patent Laid-Open No. Sho 60-37 discloses a hydraulic shock absorber.
As disclosed in Japanese Patent No. 433, a hydraulic shock absorber having a structure in which a piston rod sliding through an oil seal disposed at one end of a cylinder in which hydraulic oil is sealed is immersed in hydraulic oil outside the cylinder is disclosed. It has been disclosed. And, since the oil seal is shaped to prevent the hydraulic oil in the cylinder from leaking out of the cylinder, the hydraulic oil outside the cylinder gradually enters the cylinder while the shock absorber repeats the expansion and contraction, The pressure inside the cylinder increases, leading to deterioration of the cushioning performance and damage to various parts of the cylinder. Therefore, according to Japanese Patent Application Laid-Open No. 60-37433, a free piston is provided at the end of the cylinder to define a gas chamber, and the gas chamber absorbs a volume change in the cylinder and the free piston moves to a predetermined position. A pressure absorbing mechanism is provided to open a relief passage communicating with the outside of the cylinder when it moves, and to return excess hydraulic oil to the outside of the cylinder.

[0003]

According to the above-described hydraulic shock absorber, it is possible to prevent each part of the cylinder from being damaged due to an increase in the pressure of the gas chamber, but it is necessary to provide a damping force mechanism on the side where the free piston is provided. I can no longer do it.

[0004]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention is to insert a piston rod into a cylinder filled with hydraulic oil, attach an oil seal to one end of the cylinder, and mount the other end of the cylinder. A pressure absorbing mechanism is provided, and the pressure absorbing mechanism defines an oil chamber in the cylinder and a gas chamber connected to an oil chamber outside the cylinder by a slidable partition member urged by a spring. Further, the shaft penetrates through the partition member and faces the inside of the cylinder, a pressure-side damping force mechanism is disposed at the tip side of the shaft, and further when the partition member moves to a predetermined position on the outer peripheral surface of the shaft, the partition member uses A passage connecting the defined oil chamber and gas chamber was formed.

[0005]

When the shock absorber repeats the expansion and contraction movement, the hydraulic oil outside the cylinder is brought into the cylinder, whereby the sliding position of the partition member gradually rises. When the partition member rises to the reduced diameter portion of the hollow shaft, the hydraulic oil flows into the gas chamber through the reduced diameter portion, and the hydraulic oil further flows into the gas chamber through the oil hole formed in the case. Return to the oil chamber.

[0006]

Embodiments of the present invention will be described below with reference to the accompanying drawings. Here, FIG. 1 is a cross-sectional view of a main part of the hydraulic shock absorber according to the present invention, FIG. 2 is an enlarged cross-sectional view of a main part of FIG. 1, FIG. 3 is an enlarged cross-sectional view of a part related to the suspension spring locking structure of FIG. FIG.
FIG. 4 is an exploded perspective view of FIG.

In the hydraulic shock absorber, an inner tube 2 is slidably inserted into the outer tube 1 from below, and a bush 3 slidingly contacting the outer peripheral surface of the inner tube 2 is fitted to the inner peripheral surface of the lower end of the outer tube 1. A bush 4 that is in sliding contact with the inner peripheral surface of the outer tube 1 is fitted to the outer peripheral surface of the upper end portion of the inner tube 2.

A case 5 is provided at the upper end of the outer tube 1.
The upper end of a cylinder 6 facing the inside of the inner tube 2 is screwed to the lower end of the case 5. A bracket 7 for mounting an axle is mounted on the outer periphery of the lower end of the inner tube 2, and an oil lock piece 8 is fitted on the inner periphery of the lower end of the inner tube 2. The hollow rod 10 is fixed to the bracket 7 by screwing the lower end of the hollow rod 10 to the bottom bolt 9. The distal end of the hollow rod 10 faces the cylinder 6.

A hollow piston support member 11 is mounted on the distal end of the hollow rod 10, and the piston 1 sliding on the inner peripheral surface of the cylinder 6 is attached to the piston support member 11.
2, a compression-side oil passage 13 and an extension-side oil passage 14 are formed in the piston 12, and a compression-side valve 15 and an extension-side valve for opening and closing the compression-side oil passage 13 and the extension-side oil passage 14 respectively. 16 is attached. A needle 17 is inserted into the hollow rod 10 so as to be able to advance and retreat.
The lower end of 7 is attached to an adjuster piece 18.

A rod guide 21 is screwed into the lower end of the cylinder 6, and an oil lock collar 20 is loosely fitted in the lower end of the cylinder 6. Bush 22 slidingly contacting the outer peripheral surface
, And the hollow rod 10 is inserted above the rod guide 21.
An oil seal 23 that is in sliding contact with the outer peripheral surface is fitted. Each time the shock absorber strokes, the oil seal 23 gradually takes in the working oil attached to the outer peripheral surface of the hollow rod 10 into the oil chamber S2 in the cylinder.

Further, a damping force adjusting mechanism and a pressure absorbing mechanism are provided at the upper end of the outer tube 1. That is, a fork bolt 25 is screwed to the upper end of the case 5 screwed to the upper end of the outer tube 1.
, The upper end of the hollow shaft 26 is fixed and suspended in the case 5. A hollow piston support member 27 is fitted to the lower end of the hollow shaft 26, and a piston 28 that is in contact with the inner peripheral surface of the cylinder 6 via an o-ring is fitted to the lower end of the piston support member 27. Piston 28
A compression-side oil passage 30 and an extension-side oil passage 31 are formed, and a compression-side valve 32 and an extension-side valve 33 that open and close the compression-side oil passage 30 and the extension-side oil passage 31 are fitted.
An externally operable needle 34 is screwed into the hollow shaft 26 so as to be able to advance and retreat.

A groove 36 is formed on the outer peripheral surface of the case 5, and an oil hole 37 communicating the groove 36 with the gas chamber in the case 5 is formed. A diaphragm 38 as a partition member that slides on the outer peripheral surface of the hollow shaft 26 is fitted, and a spring 39 is interposed between the diaphragm 38 and the fork bolt 25 to pressurize hydraulic oil in the cylinder 6 to pressurize the hydraulic oil in the cylinder 6. I have. Further, the middle portion of the hollow shaft 26 has a reduced diameter portion 2 having a small outer peripheral surface.
6a.

Further, as shown in FIGS. 3 and 4, an annular groove 40 is formed on the outer peripheral surface of the cylinder 6, and two divided cotters 41, 41 are fitted in the annular groove 40. By attaching a cover 42 fitted from below the cylinder 6 to the outer peripheral surface of the cotter 41,
1 is fixed to the cylinder 6, and a grooved member 43 is fitted between the outer peripheral surface of the cylinder 6 and the inner peripheral surface of the cover 42 above the cotters 41, 41 (the state shown in the right half of FIG. 3). The upper end of the cover 42 is swaged into a groove 44 formed on the outer peripheral surface of the grooved member 43 (the state shown in the left half of FIG. 3), and the cotter 41, the cover 42 and the grooved member 43 are It is fixed to the outer peripheral surface. The upper end of a suspension spring 46 interposed between the lower end surface of the cover 42 and a spring receiver 45 mounted on the outer peripheral surface of the upper end of the oil lock collar 8 is locked. 47 are mounted.

In the hydraulic shock absorber constructed as described above, the hydraulic oil in the oil chamber S1 is expanded and contracted by the hollow rod 10
Since the hydraulic oil adhering to the outer peripheral surface of the hollow rod 10 has directionality in the oil seal 23 of the cylinder 6, a small amount of the hydraulic oil enters the oil chamber S 2 in the cylinder via the oil seal 23. After flowing, the amount of hydraulic oil in the oil chamber S2 increases for a long time.

As the hydraulic oil is accumulated in the oil chamber S2 and the internal pressure increases, friction increases through the seal portion. In this hydraulic shock absorber, however, the oil flows into the oil chamber S2. The operating oil flows into the lower space S3 of the diaphragm 38 of the case 5 via the piston 28, and gradually pushes up the stroke center of the diaphragm 38. Then, the diaphragm 38 is connected to the reduced diameter portion 26 of the hollow shaft 26.
When pushed up to the position a, the hydraulic oil in the space S3 becomes
Since the gas flows between the inner diameter seal portion of the diaphragm 38 and the reduced diameter portion 26a of the hollow shaft 26 and returns to the cylinder outside oil chamber S2 again through the oil hole 37 and the groove 36 of the case 5,
Large changes in friction and breakage of each part are prevented.

[0016]

According to the present invention as described above,
The shaft penetrates through the partition member that slides according to the volume of hydraulic oil in the cylinder to face the cylinder, a damping force mechanism is provided at the tip of this shaft, and hydraulic oil escapes to the outer periphery of the shaft. Since the passage is formed, the pressure absorbing mechanism and the damping force mechanism can be arranged at the same location without difficulty, and a constant buffer characteristic can be maintained.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part of a hydraulic shock absorber according to the present invention.

FIG. 2 is an enlarged sectional view of a main part of FIG. 1;

FIG. 3 is an enlarged sectional view of a portion related to the suspension spring locking structure of FIG. 1;

FIG. 4 is an exploded perspective view of FIG. 3;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Outer tube, 2 ... Inner tube, 5 ... Case, 6 ... Cylinder, 10 ... Hollow rod, 12 ... Piston, 26 ... Hollow shaft, 38 ... Diaphragm, 40 ...
Cylinder groove, 41 ... cotter, 42 ... cover, 43 ...
Grooved member, 44: Groove of grooved member, 46: Suspension spring, 47: Return spring.

Claims (1)

(57) [Claims] 1. A piston rod is inserted into a cylinder filled with hydraulic oil, an oil seal is provided on one end side of the cylinder so as to slidably contact an outer peripheral surface of the piston rod, and a partition member is provided on the other end side of the cylinder. In a hydraulic shock absorber provided to define a gas chamber and communicate between the inside of the cylinder and the outside of the oil seal, the pressure absorbing mechanism slides a partition member biased by a spring in the cylinder. The partition member defines an oil chamber inside the cylinder and a gas chamber connected to the oil chamber outside the cylinder, and the shaft penetrates the partition member to face the inside of the cylinder. A communication path in which a pressure-side damping force mechanism is disposed on the distal end portion, and further connects the oil chamber and the gas chamber defined by the partition member when the partition member moves to a predetermined position on the outer peripheral surface of the shaft. A hydraulic shock absorber characterized by forming: