JPH0882336A - Hydraulic shock absorber - Google Patents

Abstract

PURPOSE: To provide a hydraulic shock absorber that can reduce the inner diameter of a recessed part in a rod guide without changing the inner diameter of a check seal so as to enable cost reduction through the common use of the oil seal and can maintain the function and durability of a check lip. CONSTITUTION: A vertical groove 77a recessed outside from the contact face of a check lip 11d is formed at a part of the inner peripheral surface of an annular rising part 77 in a rod guide 7 brought into contact by the outward deflection of the check 11p lid at the valve opening time, and a communicating groove 11e communicated with a reservoir chamber C through a cutout part 72a is formed on the lower face side of a reinforcing ring 11a opposed to a flange part 72, the uppermost end face of the rod guide 7, in the state of being communicated with the vertical groove 77a.

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 used in a vehicle, and more particularly to improvement of a check seal structure in a rod guide section.

[0002]

2. Description of the Related Art Conventionally, a check seal structure in such a hydraulic shock absorber is, for example, an actual open flat plate 2-110.
No. 730, FIG. 4, Japanese Utility Model Laid-Open No. 3-68649, and FIG. 5 of Japanese Utility Model Laid-Open No. 4-27235.

Of these conventional hydraulic shock absorbers, the actual flatbed 2
In FIG. 4 of Japanese Patent Application Laid-Open No. -110730, a reservoir chamber in which gas is enclosed is formed between a cylinder tube and an outer tube that are double formed inside and outside, and inside the upper end opening of the cylinder tube and the outer tube. Rod guides are provided that are fitted around the circumference and guide the sliding of the piston rod, and an annular recess communicating with the reservoir chamber by a communication passage is formed on the upper surface of the inner circumference side of the rod guide.
A rod seal that slidably seals between the inner peripheral surface of the outer tube opening and the outer peripheral surface of the piston rod in the opening of the outer tube at the upper part of the rod guide.
As shown in the cross section of the main part thereof, gas is prevented from entering the recess 22 of the rod guide 21 in the direction of the recess 22 from the reservoir chamber 27 via the communication passage 23 formed on the upper surface side of the rod guide 21. It has a structure in which an oil seal having a skirt-shaped check lip 24 is fitted.

Further, the first of Japanese Utility Model Laid-Open No. 3-68649 No. 1
The drawing and the one shown in FIG. 5 of Japanese Utility Model Application Laid-Open No. 4-27235 have a cross section as shown in FIG. 12 and FIG.
The structure shown in FIG. 1 of Japanese Utility Model Laid-Open No. 2-110730 is that the opening of the communication passage 23 is formed at the same level as the seal surface 26 with which the check lip 24 abuts. Are different. In addition, the actual Kaihei 4-
The one shown in FIG. 5 of Japanese Patent No. 27235 differs from the others in that the rod guide 21 is formed by press molding of a plate material.

[0005]

However, among the conventional hydraulic shock absorbers as described above, the actual open-air plane 2-110730.
In the structure shown in FIG. 4 of the publication, as described above, since the communication passage 23 is formed on the upper surface side of the rod guide 21, there are problems as described below. It was

That is, when the internal pressure of the concave portion 22 exceeds a certain pressure, as shown in the cross section of the essential part of FIG. The hydraulic oil in the recess 22 that opens and flows out from the opening to the reservoir chamber 27 side via the communication passage 23, but at this time, the inner diameter of the recess 22 in the rod guide 21 is reduced due to size setting or strength. In this case, when the check lip 24 is opened, the outer peripheral edge portion of the check lip 24 comes into contact with the inner peripheral surface of the recess 22.
There is a possibility that the check lip 24 may not be able to perform the function of venting the check lip 24 in the direction of the reservoir chamber 27 and the function of recirculating the hydraulic oil, thereby impairing the performance and durability.

The recess 22 in the rod guide 21
If the inner diameter of the check lip 24 is reduced in order to avoid the contact of the check lip 24 with the inner peripheral surface of the, the performance is deteriorated due to a change in rubber rigidity, and parts cannot be shared, which results in cost reduction. It creates another problem of disadvantage.

On the other hand, those shown in FIG. 1 of Japanese Utility Model Laid-Open No. 3-68649 and FIG. 5 of Japanese Utility Model Laid-Open No. 4-27235, as shown in the cross-sections of the essential parts of FIGS. Since the opening of the communication passage 23 is formed at the same level position as the seal surface 26 with which the check lip 24 abuts, the above problem does not occur, but up to the same level as the seal surface 26 indicated by the one-dot chain line. However, since the hydraulic oil does not collect in the recess 22, there is a problem that the deterioration of the check lip 24 due to the hydraulic oil is prevented from being deteriorated and the durability due to the cooling action cannot be maintained.

The present invention has been made by paying attention to the above-mentioned conventional problems, and it is possible to reduce the inner diameter of the recess in the rod guide without changing the inner diameter of the check seal and to reduce the cost by sharing the oil seal. It is an object of the present invention to provide a hydraulic shock absorber that is capable of reducing the number of times and can maintain the function and durability of a check lip.

[0010]

In order to achieve the above-mentioned object, in the hydraulic shock absorber of the present invention, gas is enclosed between the cylinder tube and the outer tube which are double-shaped inside and outside. A reservoir chamber is formed, and rod guides that are fitted to the inner peripheries of the upper ends of the cylinder tube and the outer tube to guide the sliding of the piston rod are provided. An annular recess communicating with the chamber is formed, and a rod seal that slidably seals between the inner peripheral surface of the outer tube opening and the outer peripheral surface of the piston tube is formed in the outer tube opening above the rod guide. In the recess of the rod guide, a skirt-shaped checker that opens in only one direction to prevent gas from entering from the reservoir chamber to the recess via the communication passage. In a hydraulic shock absorber in which an oil seal having a lip is fitted, a part of the inner peripheral surface of the recess of the rod guide that abuts due to the outward deflection when the check lip opens A means is formed in which a vertical groove portion that is recessed to the outside is formed, and a communication passage that communicates with the reservoir chamber is formed so as to communicate with the vertical groove portion and near the upper end surface of the rod guide.

[0011]

Since the hydraulic shock absorber of the present invention is configured as described above, the hydraulic oil fed to the recess side in the extension stroke of the shock absorber opens the check lip due to an increase in hydraulic pressure, It will be returned to the reservoir chamber side via the communication passage.

At this time, if the inner diameter of the recess is small,
The outer edge of the lower end of the check lip may come into contact with the inner peripheral surface of the recess due to the outward deflection when the valve is opened, but in this case as well, the vertical groove allows the hydraulic oil to flow between the recess and the communication passage. Is always secured, so that when the check lip is opened, the hydraulic oil in the recess can be returned to the reservoir chamber side by way of this vertical groove.
That is, since the inner diameter of the recess in the rod guide can be reduced, the cost can be reduced by sharing the oil seal.

Further, since the communication passage is formed in a state of passing near the upper end surface of the rod guide, it is possible to store the hydraulic oil in substantially the entire inside of the concave portion.
While the shock absorber is in operation, the entire check lip is always immersed in the hydraulic oil, so that deterioration due to wetting can be prevented and durability can be improved by the cooling action.

[0014]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 2 is a sectional view showing the entire hydraulic shock absorber according to the first embodiment of the present invention. In this figure, 1 is a cylinder tube, 2 is a piston, 3 is a rebound rubber, 4 is a piston rod, and 5 is an outer. A tube, 6 is a base, 7 is a rod guide, 11 is an oil seal, 12 is a packing land cover, A is an upper chamber, B is a lower chamber, and C is a reservoir chamber.

Next, FIG. 3 is an enlarged cross-sectional view showing a portion of the rod guide 7. As shown in this figure, the rod guide 7 of this embodiment is formed by pressing one plate material. As shown in the plan view of FIG. 4, the lower end portion is formed into a double tubular shape, and the piston rod 4 slides in the inner periphery of the lower end portion in a penetrating state. A rod support portion 74 having a hole 71 is formed, and an outward flange portion 72 is formed at the upper end. A cylinder fitting portion 73 is provided between the flange portion 72 and the rod supporting portion 74. The cylinder fitting portion 73 is fitted and supported on the inner circumference of the cylinder tube 1, and The outer periphery of the flange portion 72 is fitted into and supported by the inner periphery of the outer tube 5.

Further, between the cylinder fitting portion 73 and the flange portion 72, as shown in the enlarged cross section of the main part in FIG. 1, is bent outward from the upper end of the cylinder fitting portion 73. An annular horizontal portion 76 locked to the upper end surface of the cylinder tube 1 and an annular rising portion 7 from the outer periphery of the annular horizontal portion 76.
And 7 form an annular step having an L-shaped cross section. Then, by forming vertical grooves (vertical groove portions) 77a at four locations on the inner peripheral surface of the annular rising portion 77 at equal intervals in the circumferential direction, the outer peripheral surface of the vertical groove 77a is formed. The protruding portion 77b is in the state of being formed in a rib shape (FIG. 4, FIG.
(See FIG. 5). Further, a cutout portion 72a is formed on the outer periphery of the flange portion 72 corresponding to each of the vertical grooves 77a.

A guide bush 9 is fitted and fixed in the rod through hole 71, and a guide seal ring 8 is provided below the guide bush 9 in a state where the stopper member 75 prevents the guide seal 9 from coming off. ing. The guide seal ring 8 is provided in a substantially close contact state on the inner peripheral side thereof with a minute gap to the outer peripheral surface of the piston rod 4,
The hydraulic oil in the upper chamber A is prevented from leaking upward from the rod guide 7 (in the oil reservoir chamber D direction described later).

On the upper side of the rod guide 7, the oil seal 11 is provided. The oil seal 11 has a reinforcing ring 11a fitted to the inner circumference of the outer tube 5, and the reinforcing ring 11a has a dust lip 11b and a seal lip 11c which are in close contact with the piston rod 4 on the inner circumference side thereof. And a skirt-shaped check lip 11d on the lower surface side of which the inner peripheral edge of the lower end of the annular horizontal portion 76 of the rod guide 7 is in pressure contact with the upper surface of the annular horizontal portion 76 of the rod guide 7. .

Then, the upper end of the outer tube 5 is bent inward at the upper side of the oil seal 11 and caulked, whereby the oil seal 11 and the rod guide 7 are formed.
Is fixed while receiving the internal residual axial force.

That is, on the inner peripheral side of the upper surface of the rod guide 7,
The rod guide 7, the piston rod 4, and the oil seal 1
1. An annular oil reservoir chamber D that forms a recessed portion between the first and the second embodiments.
Are formed.

Further, on the lower surface of the outer peripheral portion of the reinforcing ring 11a in the oil seal 11, each vertical groove 77a and each notch portion 7 is formed.
Communication grooves 11e are formed so as to communicate with 2a, respectively. That is, the communication groove 11e and the cutout portion 72a constitute a communication passage in the scope of the claims for connecting the reservoir chamber C and the vertical groove 77a.

Next, the operation of the embodiment will be described. (A) At the time of stroke Since the hydraulic shock absorber of the present embodiment is configured as described above, during the stroke of the shock absorber, the upper chamber A side is pressurized due to the rise of the piston 2, so that the upper chamber A side is pressurized. A part of the hydraulic oil in A is sent to the oil reservoir chamber D side through the minute gap between the piston rod 4 and the rod guide 7, and the hydraulic oil in the oil reservoir chamber D seals the oil seal 11. The hydraulic oil in the oil reservoir chamber D is lubricated by the check lip 11 as shown by the chain line in FIG.
The valve d is opened, and the fluid is returned to the reservoir chamber C via the communication groove 11e and the cutout portion 72a.

At this time, if the inner diameter of the annular rising portion 77 is small and the offset amount F between the inner peripheral surface of the annular rising portion 77 and the valve opening center of the check lip 11d is set to be small, FIG. As shown by the alternate long and short dash line, there is a risk that the outer peripheral edge of the lower end of the check lip 11d may come into contact with the inner peripheral surface of the annular rising portion 77 due to the outward deflection when the valve is opened.
Even in this case, the ring-shaped rising portion 77 which is the corresponding contact surface
A vertical groove 77a is formed on a part of the inner peripheral surface of the check lip 11d because the hydraulic oil is always kept flowing between the oil reservoir D and the communication groove 11e. When the valve is opened, the working oil in the oil reservoir chamber D can be returned to the reservoir chamber C side by passing through the vertical groove 77a.
That is, since the inner diameter of the oil reservoir D in the rod guide 7 can be reduced, the cost can be reduced by sharing the oil seal 11.

Further, since the communication groove 11e is formed on the reinforcing ring 11a side of the oil seal 11 which faces the upper surface of the flange portion 72 which is the uppermost portion of the rod guide 7, it reaches the level of the upper surface of the flange portion 72. The hydraulic oil is stored in the entire oil storage chamber D. As a result, the entire check lip 11d is always immersed in the hydraulic oil during the operation of the shock absorber, so that deterioration due to wetting can be prevented. The durability can be improved by the cooling action.

(B) During the pressure stroke In the pressure stroke of the shock absorber, the lower chamber B side is pressurized while the lower chamber B side is pressurized due to the lowering of the piston 2, and a part of the piston rod 4 is a cylinder. Tube 1
By entering into the inside, the hydraulic oil in the lower chamber B corresponding to the entering volume is circulated from the base 6 side to the reservoir chamber C side, whereby the gas pressure in the reservoir chamber C rises, and the reservoir chamber C and the upper part Although a differential pressure is generated between the chamber A and the chamber A, the check lip 11d prevents gas from leaking from the reservoir chamber C toward the oil reservoir D.

As described above, the hydraulic shock absorber of this embodiment has the following effects. Communication groove 1 that communicates between the oil reservoir chamber D and the reservoir chamber C
By forming 1e on the side of the reinforcing ring 11a facing the upper surface of the flange portion 72, which is the uppermost portion of the rod guide 7, the entire check lip 11d can always be immersed in hydraulic oil during operation of the shock absorber. As a result, deterioration due to wetting can be prevented, and durability due to a cooling action can be improved.

Even if the check lip 11d comes into contact with the inner peripheral surface of the rising portion 77 of the rod guide 7 when the valve is opened, the vertical groove 77a can ensure the flow of hydraulic oil, so that the inner diameter of the check lip 11d can be increased. It is possible to reduce the inner diameter of the oil reservoir D in the rod guide 7 without changing it. Therefore, the cost can be reduced by sharing the oil seal 11.

Since the rod guide 7 is easily formed by press molding, the cost can be reduced, and the protrusion 77b is formed in a rib shape on the outer periphery of the vertical groove 77a by press molding. The axial strength of the rod guide 7 can be increased.

Next, another embodiment of the present invention will be described. In the description of these other embodiments, the same components as those in the first embodiment will be designated by the same reference numerals and the description thereof will be omitted, and only the differences will be described.

(Second Embodiment) As shown in FIG. 6, the hydraulic shock absorber according to the second embodiment has a flange which is continuous with the vertical grooves 77a formed in the annular rising portion 77 of the rod guide 7. A radial groove 72b is formed on the upper surface side of the portion 72 by press molding, and the radial groove 72b and the cutout portion 72 are formed.
The communication passage defined in the claims is constituted by a and a.

Therefore, also in this embodiment, since the hydraulic oil can be stored up to the level of the bottom of the radial groove 72b, the same effect as that of the first embodiment can be obtained and, in addition, the rib effect by press molding can be obtained. Flange 72
The strength of can also be increased.

(Third Embodiment) In the hydraulic shock absorber of the third embodiment, as shown in FIGS. 7 to 9, the rod guide 70 is made of a sintered metal.

That is, the rod guide 70 of this embodiment is
A first annular step portion 70a, a second annular step portion 70b, and a third annular step portion 70a that gradually decrease step by step toward the center side from the outer peripheral edge portion on which the reinforcing ring 11a of the oil seal 11 abuts, on the upper surface side thereof.
The annular step portion 70c is formed, and the first annular step portion 70 is formed.
A vertical hole 70d communicating with the reservoir chamber C is formed in a,
A vertical groove (vertical groove portion) 70e is formed on the inner peripheral surface between the first annular step portion 70a and the second annular step portion 70b, and the second annular step portion 70b constitutes a sealing surface with which the check lip 11d abuts. I am letting you.

An annular oil reservoir chamber D is formed between each of the annular step portions 70a, 70b, 70c of the rod guide 70, the piston rod 4 and the oil seal 11 and forms a concave portion of the claims. , First annular step 70a
70f and the vertical hole 70 between the oil seal 11 and the oil seal 11
The communication path defined in the claims is constructed with d.

Therefore, in this embodiment, the first annular step portion 7
The hydraulic oil can be stored up to the level of 0a, and the vertical groove 70e ensures the circulation of the hydraulic oil when the check lip 11d is opened.
In addition to the same effects as those of the first embodiment, the following effects can be obtained.

That is, since the surface of the sintered molded product is rougher than that of the press molded product, the friction resistance of the surface of the second annular stepped portion 70b, which serves as the sealing surface, is also large, and the corner portion is similar to that of a press. Since there is no radius, the effect of preventing the check lip 11d from being turned inside out when the internal pressure of the reservoir chamber C becomes higher than that of the oil reservoir chamber D in the pressure stroke is enhanced.

FIG. 10 shows a modified example of the rod guide 70 in the third embodiment. As shown in FIG. 10, the protrusion 70g is formed in place of the vertical groove 70e to form the protrusion. The recessed portion 70h other than the line 70g constitutes the vertical groove portion in the claims.

Although the embodiment of the present invention has been described in detail above with reference to the drawings, the specific structure is not limited to this embodiment, and even if there are design changes and the like within the scope not departing from the gist of the present invention. Included in the present invention.

For example, in the first embodiment, the annular rising portion 7
The vertical groove portion 77a formed on the inner peripheral surface of No. 7 constitutes the vertical groove portion in the claims. However, similar to the modification of the rod guide in the third embodiment, the vertical groove portion 77a is replaced with a protrusion. By forming it, you may make it comprise the vertical groove part of a claim by the hollow part other than this protrusion.

Further, in the third embodiment, the annular space 70a constitutes the communicating passage of the claims, but it may be constituted by a partial radial groove.

[0041]

As described above, in the hydraulic shock absorber of the present invention, the check lip is formed on a part of the inner peripheral surface of the recess of the rod guide which abuts due to the outward deflection when the check lip is opened. By forming a vertical groove portion that is recessed outward from the abutment surface of, and forming a communication path that communicates with the reservoir chamber with the vertical groove portion and near the upper end surface of the rod guide, Since the vertical groove always ensures the flow of hydraulic oil between the recess and the communication passage, when the check lip is opened, the hydraulic oil in the recess is transferred to the reservoir chamber by passing through this vertical groove. Can be refluxed. Therefore, it is possible to reduce the inner diameter of the recess in the rod guide without changing the inner diameter of the check seal, and it is possible to reduce the cost by sharing the oil seal.Also, the communication passage should pass near the upper end surface of the lot guide. Since it is formed in a closed state, the hydraulic oil can be stored in almost the entire recess, and during operation of the shock absorber, the entire check lip is always immersed in the hydraulic oil and wet. It is possible to obtain the effects that the deterioration can be prevented and the durability can be improved by the cooling action.

[Brief description of drawings]

FIG. 1 is an enlarged sectional view showing a check lip portion of an oil seal which is a main part of a hydraulic shock absorber according to a first embodiment of the present invention.

FIG. 2 is a sectional view showing the entire hydraulic shock absorber according to the first embodiment of the present invention.

FIG. 3 is an enlarged cross-sectional view showing an oil seal and a rod guide portion which are essential parts of the hydraulic shock absorber according to the first embodiment of the present invention.

FIG. 4 is a plan view showing a rod guide in the hydraulic shock absorber according to the first embodiment of the present invention.

5 is a cross-sectional view taken along the line EE of FIG.

FIG. 6 is an enlarged cross-sectional view showing an oil seal and a rod guide portion which are essential parts of a hydraulic shock absorber according to a second embodiment of the present invention.

FIG. 7 is an enlarged cross-sectional view showing an oil seal and a rod guide portion which are essential parts of a hydraulic shock absorber according to a third embodiment of the present invention.

FIG. 8 is a plan view showing a rod guide in a hydraulic shock absorber according to a third embodiment of the present invention.

FIG. 9 is an enlarged sectional view showing a check lip portion of an oil seal which is a main part of a hydraulic shock absorber according to a third embodiment of the present invention.

FIG. 10 is a plan view showing a modification of the rod guide in the hydraulic shock absorber according to the third embodiment of the present invention.

FIG. 11 is an enlarged cross-sectional view of a main part showing a conventional hydraulic shock absorber.

FIG. 12 is an enlarged sectional view of an essential part showing a conventional hydraulic shock absorber.

FIG. 13 is an enlarged sectional view of an essential part showing a conventional hydraulic shock absorber.

[Explanation of symbols]

 1 cylinder tube 4 piston rod 5 outer tube 7 rod guide 11 oil seal 11b dust lip (rod seal) 11c seal lip (rod seal) 11d check lip 11e communication groove (communication passage) 70 rod guide 70d vertical hole (communication passage) 70e Vertical groove (vertical groove portion) 70f Annular space (communication passage) 70h Depression portion (vertical groove portion) 72a Notch portion (communication passage) 77a Vertical groove (vertical groove portion) C Reservoir chamber D Oil reservoir chamber (recessed portion)

Claims (1)

[Claims] 1. A reservoir chamber, in which gas is enclosed, is formed between a cylinder tube and an outer tube, which are double formed inside and outside, and a piston rod is fitted in the inner circumference of the upper end opening of the cylinder tube and the outer tube, respectively. A rod guide for guiding the sliding of the rod guide is provided, and an annular recess communicating with the reservoir chamber by a communication passage is formed on the upper surface on the inner peripheral side of the rod guide, and in the opening of the outer tube at the upper part of the rod guide. Prevents gas from entering from the reservoir chamber to the recess via the communication passage in the recess of the rod guide and rod guide that slidably seals the inner surface of the opening of the outer tube and the outer surface of the piston rod. A hydraulic shock absorber fitted with an oil seal having a skirt-shaped check lip that opens in only one direction for A communicating groove communicating with the reservoir chamber is formed in a part of the inner peripheral surface of the recess of the rod guide that abuts due to the outward deflection when the lip is opened, Is formed so as to communicate with the vertical groove portion and pass near the upper end surface of the rod guide.