JP2003184935A - Hydraulic shock absorber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hydraulic shock absorber having a check seal capable of lessening a heat effect caused by expanding and contracting of a piston rod. <P>SOLUTION: In the hydraulic shock absorber, a rod guide 13 passing through and guiding the piston rod 2 is provided on each end portion of a cylinder 1 and an outer cylinder 6, a main seal 5 opposing to the rod guide 13 is provided within a cap 17 covering the rod guide 13, a reservoir chamber R partitioned between the cylinder 1 and the outer cylinder 6 is connected with an oil chamber 9 within the cylinder 1 via a drain hole 18 formed on the rod guide 13 and an oil passage A arranged between the rod guide 13 and the main seal 5, and the check seal 14 preventing a gaseous body fed from the reservoir chamber R from invading to the oil chamber 9 within the cylinder 1 is arranged in the middle of the oil passage A. Further in the absorber, the check seal 14 is formed by a base portion 16 and an elastic seal lip 15 combined with the base portion 16. The seal lip 15 is touched on an inner peripheral surface of the cap 17 in a free opening and shutting state while maintaining the base portion 16 on the rod guide 13. <P>COPYRIGHT: (C)2003,JPO

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 having an improved check seal structure for preventing gas such as air from entering a cylinder chamber oil chamber from a reservoir chamber.

[0002]

2. Description of the Related Art Various hydraulic shock absorbers have been developed which are equipped with a check seal mechanism for preventing gas such as air in a reservoir chamber from returning to and invading an oil chamber in a cylinder.

For example, the hydraulic shock absorber shown in FIG. 5 has a rod guide 3 which penetrates the piston rod 2 in the axial center while sealing the open end 1a of the cylinder 1, and a flange-like shape at the upper end of the rod guide 3. The upper end seal portion 4b formed in a ring shape is provided with a check seal 4 that exerts a predetermined check function while pressing the formed lower end base portion 4a by an appropriate pressing means.

At this time, a main seal 5 consisting of a dust lip and an oil seal is arranged above the rod guide 3, and the inner circumference of the main seal 5 is brought into sliding contact with the outer circumference of the piston rod 2. Thus, the dust inside is prevented from entering the inside, and the oil inside is prevented from leaking outside.

By the way, the rod guide 3 has a drain hole 3a formed in its outer slide portion and an outer cylinder 6 which is spaced from the rod guide 3, and a reservoir chamber R is provided between the outer cylinder 6 and the cylinder 1. At the same time, the drain hole 3 is provided in the reservoir chamber R.
a is opened.

The drain hole 3a communicates with an oil chamber 9 in the cylinder 1 via an oil passage A formed above the rod guide 3, and a check seal 4 is provided in the oil passage A. There is.

The ring-shaped upper end seal lip 4b of the check seal 4 is in contact with the outer periphery of the lower packing side of the downward facing packing blade 8 which locks the rear end of the coil spring 7, as shown.

Lubricating oil flows out above the rod guide 3 when the piston rod 2 repeatedly appears and disappears from the cylinder 1.

At this time, this oil is prevented from leaking to the outside by the main seal 5, while the upper seal lip 4b of the check seal 4 is opened to flow into the reservoir chamber R through the drain hole 3a. It

The check seal 4 has its upper end seal lip 4b pressed against the outer periphery of the packing plate 8 by the air pressure from the reservoir chamber R acting on the outer periphery of the reservoir chamber R through the drain hole 3a. It prevents the air or oil mixed with air from entering the oil chamber 9 in the cylinder 1.

[0011]

The hydraulic shock absorber provided with the above check seal structure does not have a structural defect, but the following improvement is desired.

That is, when the piston rod 2 repeatedly expands and contracts, its sliding resistance and vibrations cause the piston rod 2 to move.
Heat is generated in and around it, and this heat causes check seal 4
If the seal lip 4b is heated and deteriorates, the tightening margin is weakened, or the cylindrical check seal 4 expands due to thermal expansion, there is a possibility that a sufficient gas sealing function cannot be exerted.

Therefore, an object of the present invention is to provide a hydraulic shock absorber provided with a check seal which can minimize the influence of heat due to the expansion and contraction operation of the piston rod.

[0014]

To achieve the above object, one means of the present invention is to provide a rod guide for penetrating and guiding a piston rod at each end of a cylinder and an outer cylinder. A main seal is provided inside the cap that covers the rod guide, and a drain hole is formed between the cylinder and the outer cylinder. A drain chamber is formed in the rod guide, and an oil passage provided between the rod guide and the main seal. In a hydraulic shock absorber provided with a check seal for preventing gas from the reservoir chamber from entering the oil chamber in the cylinder, which is connected to the oil chamber in the cylinder via The check seal is composed of a base portion and an elastic seal lip connected to the base portion, and the seal lip is openably and closably contacted with the inner peripheral surface of the cap while the base portion is held by the rod guide. Than it is. In this case, the rod guide is press-molded to provide a central cylindrical portion and an annular groove adjacent to the cylindrical portion, and the base of the check seal is composed of a cylindrical body and a flange connected to the cylindrical body. The seal lip may be joined to the tip of the flange by press-fitting into the cylindrical portion of the guide.

Similarly, the base of the check seal is provided with a spring seat, the spring seat is placed on the rod guide, and a spring is interposed between the spring seat and the main seal, and the spring seat is held between the rod guide and the spring. May be.

Similarly, another means is to provide a rod guide for penetrating and guiding the piston rod at each end of the cylinder and the outer cylinder, and to provide a main seal in the cap covering the rod guide so as to face the rod guide. A reservoir chamber formed between the cylinder and the outer cylinder is connected to the oil chamber in the cylinder via a drain hole formed in the rod guide and an oil passage provided between the rod guide and the main seal. In a hydraulic shock absorber provided with a check seal for preventing gas from the reservoir chamber from entering the oil chamber in the cylinder in the middle of, the check seal is composed of a base and an elastic seal lip connected to the base. The rod guide is press-molded to form a central cylindrical portion, an annular groove adjacent to the outside of the cylindrical portion, and an annular space continuous with the annular groove. Provided di-shaped engaging portion, and is characterized in that is opened and closed freely abut on the engaging portion of the seal lip while clamping the base of the check seal between the rod guide and the cap.

In this case, a horizontal portion is provided at the end of the rod guide, and a horizontal holding portion facing the horizontal portion is formed on the cap. The horizontal portion and the holding portion hold the check seal base while holding it horizontally. You may let me.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 1 to 3 show an embodiment in which each seal lip 15 of the check seal 14 is brought into contact with the inner peripheral surface of the cap 17.

The hydraulic shock absorber showing the embodiment of each drawing is shown in FIG.
In the same manner as in the conventional example, a rod guide 13 that penetrates and guides the piston rod 2 is provided at each end of the cylinder 1 and the outer cylinder 6, and a cap 17 that covers the rod guide 13 is provided inside the cap 17 so as to face the rod guide 13. A seal 5 is provided, and a drain hole 18 is formed in the rod guide 13 and a reservoir chamber R is formed between the cylinder 1 and the outer cylinder 6, and an oil passage A is provided between the rod guide 13 and the main seal 5. Cylinder 1
A check seal 14 is provided in the middle of the oil passage A for preventing gas from the reservoir chamber R from entering the oil chamber 9 inside the cylinder 1 while being connected to the oil chamber 9 inside.

In the present invention, the check seal 14 is composed of a base portion 16 and an elastic seal lip 15 connected to the base portion 16, and the seal lip 15 is held on the inner circumference of the cap 17 while the base portion 16 is held by the rod guide 13. It is characterized by being brought into contact with the horizontal portion of the surface from below so as to be openable and closable.

In this case, in the embodiment shown in FIGS.
The rod guide 13 is press-molded to provide a central cylindrical portion 19 and an annular groove 20 adjacent to the cylindrical portion 19. Further, in FIG. 1, the base portion 16 of the check seal 14 is composed of a cylindrical body 16a and a horizontal flange 16b connected to the cylindrical body, and the cylindrical body 16a is press-fitted into the cylindrical portion 19 of the rod guide 13 to seal the end of the flange 16b. The lip 15 is joined.

On the other hand, in the embodiment of FIG. 2, the base portion 16 of the check seal 14 is provided with a cylindrical seat portion 16c and a horizontal spring seat 16d, the spring seat 16d is placed on the rod guide 13, and the spring seat 16d and the main seal 15 are provided. A spring 21 is interposed between the rod guide 13 and the spring 21, and the spring seat 16d
To hold the check seal 14 in a stable manner.

Further, in the embodiment shown in FIG. 3, the rod guide 13 is formed to have the same thickness as that of the conventional example, the drain hole 18 is provided on the outer peripheral side thereof, and the annular recess 22 is formed on the upper portion.

Then, the base portion 16 of the check seal 14 is connected to the cylindrical portion 16f and the upper and lower ends of the cylindrical portion 16f, and a horizontal portion 16 is provided.
g and a horizontal spring seat 16e.
Further, the spring 21 is interposed between the spring seat 16e and the main seal 5, and the recess 22 of the rod kite 13 is provided.
By holding the spring seat 16e between the upper surface and the spring 21, the entire check seal 14 is stabilized.

According to the check seal 14 according to each of the embodiments shown in FIGS. 1, 2 and 3, the seal lip 15 contacts the inner peripheral surface of the cap 17, and the contact position is at the piston rod 2 or Since it is far from the sliding portion around it, it is hardly affected by the heat due to the sliding of the piston rod 2, and deterioration due to heat is prevented, and even if the cylindrical check seal expands due to thermal expansion. However, since the contact state between the seal lip 15 and the inner peripheral surface of the cap 17 does not change, the tightening margin does not become weak, and the reverse flow of gas can be reliably prevented.

The seal lip 15 allows the oil flow from the oil passage A, and is pressed against the gas flow from the reservoir chamber R by the cap 17 to act in the direction of closing the oil passage A.

FIG. 4 shows another embodiment of the present invention.

The hydraulic shock absorber according to this embodiment is similar to the above-described embodiments in that the rod guide 13 that guides the piston rod 2 through each end of the cylinder 1 and the outer cylinder 6 is provided.
And a main seal 5 is provided in the cap 17 that covers the rod guide 13 so as to face the rod guide 13, and a reservoir chamber R that is separated between the cylinder 1 and the outer cylinder 6 is formed in the rod guide 13. 18 and rod guide 13
And the oil passage A provided between the main seal 5 and the oil chamber 9 in the cylinder 1 so that the gas from the reservoir chamber R enters the oil chamber 9 in the cylinder 1 in the middle of the oil passage A. A check seal 14 is provided to prevent this.

In the present invention, the check seal 14
Elastic seal lip 15 connecting the base 26 to the base 26
It consists of and. Further, the rod guide 13 is press-molded to form a central cylindrical portion 27, an annular groove 28 adjacent to the outside of the cylindrical portion 27, and an annular space 29 continuous with the annular groove 28. Further, the cylindrical portion 27 of the rod guide 13
A flange-shaped locking portion 30 is provided on the top of the check seal 1
While holding the base portion 26 of No. 4 by the rod guide 13 and the cap 17, the seal lip 15 is brought into contact with the lower surface of the locking portion 30 so as to be openable and closable.

In this case, as shown, the rod guide 1
The horizontal portion 31 is provided at the end of the horizontal portion 3, and the horizontal pressing portion 32 that faces the horizontal portion 31 is formed on the cap 17.
The check seal 14 is stabilized by holding the base portion 26 of the check seal 14 horizontally by the 1 and the pressing portion 32.

In this embodiment, the check seal 14
When the gas from the reservoir chamber R tries to flow backward, the seal lip 15 comes into contact with the locking portion 30 and is pressed to the locking portion 30 side by this gas pressure, and operates in the direction to close the oil passage A. Invasion into the oil chamber 9 side is reliably prevented.

Further, since the position of the seal lip 15 is arranged on the back side of the engaging portion and is apart from the sliding position of the piston rod 2, it is less susceptible to the heat generated when the piston rod 2 slides, and its deterioration or , It is possible to prevent the tightening margin from weakening. Further, since the seal lip 15 is provided close to the annular groove 28 and the space 29, the working oil can be cooled and is not affected by the heat of the heated oil.

[0034]

The present invention has the following effects.

1) According to the invention of each claim, since the seal lip of the check seal is in contact with the locking portion of the cap or the rod guide far from the sliding portion of the piston rod, it is caused when the piston rod expands and contracts. It is less susceptible to heat generated by friction, vibration, etc., and can prevent deterioration due to heat and prevent the tightening margin from weakening.

2) According to the inventions of claims 2, 3 and 5, the base portion of the check seal is fixed and the entire check seal can be stabilized without moving.

[Brief description of drawings]

FIG. 1 is a partially longitudinal front view of a hydraulic shock absorber according to an embodiment of the present invention.

FIG. 2 is a partially longitudinal front view of a hydraulic shock absorber according to another embodiment.

FIG. 3 is a partially longitudinal front view of a hydraulic shock absorber according to another embodiment.

FIG. 4 is a partially longitudinal front view of a hydraulic shock absorber according to another embodiment.

FIG. 5 is a partially longitudinal front view of a conventional hydraulic shock absorber.

[Explanation of symbols]

1 cylinder 2 piston rod 5 Main seal 6 outer cylinder 9 oil chamber 13 Rod guide 14 Check stickers 15 seal lip 16 base 16a cylinder 16b flange 16e, 16d Spring seat 17 Cap 18 drain hole 19,27 Cylindrical part 20,28 annular groove 21 spring 29 space 30 Locking part 31 Horizontal part 32 Presser part A oil passage R reservoir chamber

Claims (5)

[Claims] 1. A cylinder and an outer cylinder are provided with rod guides penetrating and guiding a piston rod at respective ends of the cylinder and the outer cylinder, and a main seal is provided in a cap covering the rod guide so as to face the rod guide. A reservoir chamber separated from the oil chamber in the cylinder through a drain hole formed in the rod guide and an oil passage provided between the rod guide and the main seal. In a hydraulic shock absorber provided with a check seal for preventing gas from the chamber from entering the oil chamber in the cylinder, the check seal is composed of a base portion and an elastic seal lip connected to the base portion, and the base portion is a rod. A hydraulic shock absorber characterized in that a seal lip is held in contact with an inner peripheral surface of a cap while being held by a guide so as to be openable and closable. 2. A rod guide is press-molded to provide a central cylindrical portion and an annular groove adjacent to the cylindrical portion, and the base of the check seal is composed of a cylindrical body and a flange connected to the cylindrical body.
The hydraulic shock absorber according to claim 1, wherein the cylindrical body is press-fitted into the cylindrical portion of the rod guide, and the seal lip is coupled to the tip of the flange. 3. The base of the check seal is provided with a spring seat, and the spring seat is placed on the rod guide,
The hydraulic shock absorber according to claim 1, wherein a spring is interposed between the spring seat and the main seal, and the spring seat is held by the rod guide and the spring. 4. A cylinder and an outer cylinder are provided with rod guides penetrating and guiding the piston rod at respective ends of the cylinder and the outer cylinder, and a main seal is provided in a cap covering the rod guide so as to face the rod guide. A reservoir chamber separated from the oil chamber in the cylinder through a drain hole formed in the rod guide and an oil passage provided between the rod guide and the main seal. In a hydraulic shock absorber provided with a check seal that prevents gas from the chamber from entering the oil chamber in the cylinder, the check seal is composed of a base and an elastic seal lip connected to the base, and the rod guide is By press molding, a central cylindrical portion, an annular groove adjacent to the outside of the cylindrical portion, and an annular space continuous with the annular groove are formed, and a flange-shaped locking portion is provided on the cylindrical portion of the rod guide. A hydraulic shock absorber characterized in that the base of the check seal is held by the rod guide and the cap while the seal lip is openably and closably abutted against the locking portion. 5. A horizontal portion is provided at the end of the rod guide, and a horizontal holding portion is formed on the cap so as to face the horizontal portion,
The hydraulic shock absorber according to claim 5, wherein the horizontal portion and the holding portion hold the check seal while the base portion of the check seal is oriented horizontally.