JPH07317824A - Rod guide structure of liquid pressure buffer - Google Patents

Abstract

PURPOSE:To provide a rod guide structure of liquid pressure buffer, which can bleed air sufficiently while a stabilized damping force is maintained. CONSTITUTION:A rod guide structure of a liquid pressure buffer is equipped with a rod guide 7 installed at the two open ends of a cylinder tube 1 and an outer tube 5 forming a reserver chamber C at the periphery of the cylinder tube 1 and provided in the center with a rod inserting hole 71 to guide the sliding motion of the piston rod 4 and an oil seal 11 furnished at the top opening of the outer tube 5 in the upper part of the rod guide 4 and sealing the piston rod 4 slidably Between the rod guide 7 and oil seal 11 a ring-shaped space 10 for storing the working oil is formed on the oversurface side of the rod guide 7, while an air bleeding small hole 76 to put the upper chamber A of the cylinder tube 1 in communication at all times with the ring-shaped space 10, and a communication groove 11d and notch 72a to put the ring-shaped space 10 in communication with the reserver chamber C are formed in the upper part of the rod guide 7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rod guide structure for a hydraulic shock absorber, and more particularly to a technique for bleeding air from a cylinder tube.

[0002]

2. Description of the Related Art Conventionally, as a rod guide structure for a hydraulic shock absorber, for example, the actual application of the above-mentioned Japanese Utility Model Application No.
There is one such as that described in No. 121247.

The rod guide structure of this conventional hydraulic shock absorber is provided below the seal housing defined by the cylinder tube opening and the oil seal, and has a rod guide hole at the center, and A guide bush, which is provided in the rod insertion hole and guides the piston rod slidably with a minute gap, and a guide bush, which is arranged in the rod insertion hole and can be in close contact with the lower end surface of the guide bush, and between the inner circumference of the rod insertion hole. A seal ring made of Teflon slidably mounted on the piston rod with a clearance for air bleeding, and stopper means provided below the seal ring and preventing the seal ring from falling out of the rod insertion hole. And a cutout portion formed at the lower end of the guide bush and connecting the minute gap and the air bleeding gap. It was.

That is, in this conventional structure, due to the notch formed in the lower end surface of the guide bush with which the seal ring is in close contact, a flow path for air bleeding during the expansion side stroke (air bleeding gap-notch-small gap). ) Is ensured, and thus, even if the movement amount of the seal ring is reduced, a sufficient air bleeding effect can be obtained.

[0005]

However, in such a conventional rod guide structure of the hydraulic shock absorber,
There were problems as described below.

That is, in the conventional structure, in order to improve the air bleeding property, the annular cross-sectional area of the air bleeding gap formed between the outer diameter of the seal ring and the inner diameter of the rod guide is used as the air bleeding passage. However, in the annular area, it is difficult to control the flow passage cross-sectional area in terms of dimensional accuracy, and as described above, since the seal ring is made of Teflon, its upper surface repeatedly collides with the lower surface of the guide bush having the cutout portion. Therefore, it is difficult to maintain the flow passage cross-sectional area of the cutout portion.Therefore, the damping force may not be stable due to the fluctuation of the leakage amount especially at low speed operation of the piston. there were.

The present invention has been made by paying attention to the conventional problems as described above, and has a rod guide structure for a hydraulic shock absorber capable of obtaining a sufficient air bleeding effect while stabilizing the damping force. The purpose is to provide.

[0008]

In order to achieve the above-mentioned object, in the rod guide structure of the hydraulic shock absorber of the present invention, both open ends of the cylinder tube and the outer tube forming the reservoir chamber on the outer circumference thereof. Is provided in the central part and has a rod insertion hole for guiding the sliding of the piston rod in the central part, and the piston rod is slidable at the upper end opening of the outer tube above the rod guide. An oil seal that seals the inside of the cylinder tube is formed on the upper surface side of the rod guide for accumulating the working fluid between the rod guide and the oil seal. An air bleeding small hole that always communicates with the recess is formed, and a communication passage that constantly communicates between the recess and the reservoir chamber is formed at the upper part of the rod guide. It was by that means.

[0009]

In the rod guide structure of the hydraulic shock absorber of the present invention,
With the configuration described above, during the expansion stroke of the shock absorber in which the inside of the cylinder tube is pressurized by the rise of the piston and the inside of the reservoir chamber is depressurized, the hydraulic fluid in the cylinder tube is reduced due to the differential pressure. The hydraulic fluid or air stored in the recess passes through the hole and flows out to the recess, and is discharged to the reservoir chamber via the communication passage.

Therefore, the air mixed in the cylinder tube is always discharged to the concave side. Then, as described above, the flow rate of the hydraulic fluid from the cylinder tube to the recess is regulated by the opening cross-sectional area of the small hole and there is no fear of fluctuation, so the leak rate can be easily controlled, and therefore,
The damping force can be stabilized.

Further, during the pressure side stroke of the shock absorber in which the hydraulic pressure in the cylinder tube is reduced by the downward movement of the piston and the inside of the reservoir chamber is pressurized, a differential pressure in the opposite direction is generated, but in the concave portion. Since the working fluid is stored in the cylinder, the working fluid first flows into the cylinder tube through the small hole, and this prevents air from being sucked into the cylinder tube.

[0012]

Embodiments of the present invention will now be described in detail with reference to the drawings. First, the configuration of the embodiment will be described. FIG. 2 is an overall sectional view showing a rod guide structure of a hydraulic shock absorber according to an 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 a piston rod. An outer 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. 1 is an enlarged half sectional view showing a portion of the rod guide 7. As shown in FIG. 1, the rod guide 7 is formed by press-molding one circular plate material. It is formed into a double cylinder at the lower end,
A rod support portion 74 having a rod through hole 71 through which the piston rod 4 slides in a penetrating state is formed on the lower end portion, and an outward flange 72 is formed on the upper end.
Are formed. A cylinder fitting portion 73 is provided between the flange 72 and the rod support portion 74. The cylinder fitting portion 73 is fitted and supported on the inner circumference of the cylinder tube 1, and The outer peripheral surface of the flange 72 is in contact with and supported by the inner periphery of the outer tube 5. A cutout 72a is formed in a part of the outer circumference of the flange 72.

By constructing the rod guide 7 by pressing the plate material as described above, the annular space 1 forming a recess for accumulating hydraulic oil on the upper surface side thereof.
0 is formed.

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 with a stopper member 75 preventing the guide seal ring from coming off. ing. The guide seal ring 8 has an inner peripheral surface closely attached to the piston rod 4, and an upper surface thereof contacts a lower end surface of the guide bush 9 so that a space between the outer peripheral surface of the piston rod 4 and the inner peripheral surface of the guide bush 9 is formed. By sealing the gap of the above, the fluid in the upper chamber A is prevented from leaking toward the annular space 10 of the rod guide 7.

The oil seal 11 is provided above the rod guide 7. This oil seal 11
Is a reinforcing ring 1 fitted to the inner circumference of the outer tube 5.
The reinforcing ring 11a is provided with a dust lip 11b and a seal lip 11c on the inner peripheral side thereof in a state of being in close contact with the outer peripheral surface of the piston rod 4.

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

A small hole 76 is formed at the connecting portion between the cylinder fitting portion 73 and the rod supporting portion 74 of the rod guide 7 so that the upper chamber A and the annular space 10 are constantly communicated with each other. The communicating groove 11 is formed in the outer peripheral portion of the lower surface of the rod guide 11a that coincides with each cutout portion 72a of the flange 72.
d is formed, that is, by passing through the small hole 76, the annular space 10, the communication groove 11d, and the notch 72a, the upper part of the upper chamber A and the upper part of the reservoir chamber C are always communicated with each other. It is in a state.

Next, the operation of the embodiment will be described. (A) At Stretch Side Stroke Since the rod guide structure of the hydraulic shock absorber of the present embodiment is configured as described above, the piston 2 rises inside the cylinder tube 1 at the stretch side stroke of the shock absorber. As a result, the hydraulic oil on the upper chamber A side is pressurized and the lower chamber B side is depressurized, and at the same time, the hydraulic oil equivalent to the volume of the piston rod 4 withdrawing to the outside of the cylinder tube 1 is transferred from the reservoir chamber C side to the lower chamber B side. As a result, the differential pressure is generated between the upper chamber A and the reservoir chamber C. Due to this differential pressure, the hydraulic oil in the upper chamber A is small (because it is regulated by the small holes 76). However, the hydraulic oil or the air stored in the annular space 10 flows out in the direction of the reservoir chamber C via the communication groove 11d and the cutout 72a. To do.

Therefore, the air mixed in the upper chamber A is always discharged to the annular space 10 side. Then, as described above, the flow rate of the hydraulic oil from the upper chamber A to the annular space 10 is regulated by the small holes 76 and is not likely to fluctuate. Therefore, it is easy to manage the leak rate. The damping force can be stabilized.

(B) Pressure Side Stroke During the pressure side stroke of the shock absorber, the piston 2 descends inside the cylinder tube 1 to reduce the pressure of the hydraulic oil in the upper chamber A, and the hydraulic oil in the lower chamber B is added. The hydraulic oil corresponding to the volume of the piston rod 4 entering the cylinder tube 1 while being pressed is pushed out from the lower chamber B side to the reservoir chamber C side, so that the differential pressure between the upper chamber A and the reservoir chamber C is increased. However, since the hydraulic oil is stored in the annular space 10, the hydraulic oil first flows into the upper chamber A side through the small holes 76, and therefore the upper chamber A side No air is sucked in.

As described above, the following effects can be obtained in the rod guide structure of the hydraulic shock absorber of this embodiment. That is, in this embodiment, the annular space 10 forming the recess for accumulating the hydraulic oil is formed on the upper surface side of the rod guide 7, and the space between the cylinder tube 1 and the annular space 10 is formed at the bottom of the rod guide 7. A small hole 76 for constant air release is formed, and the upper part of the rod guide 7 is
The small groove 7 is formed by forming the communication groove 11d and the cutout portion 72a that always communicate between the annular space 10 and the reservoir chamber C.
6 provides an effect that a sufficient air bleeding effect can be obtained while stabilizing the damping force.

Further, in this embodiment, since the rod guide 7 is formed by press-forming the plate material, the concave portion can be easily formed and the small hole 76 is formed.
Is formed by making holes, so that the dimensional control of the opening cross-sectional area is easy.

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 is a design change or the like within a range not departing from the gist of the present invention. Included in the present invention.

[0025]

As described above, in the rod guide structure of the hydraulic shock absorber of the present invention, the working fluid is stored on the upper surface side of the rod guide between the rod guide and the oil seal. Is formed in the bottom portion of the rod guide, and a small hole for air release that always communicates between the inside of the cylinder tube and the recess is formed in the bottom of the rod guide. With the configuration in which the communication passages that communicate with each other are formed, it is possible to obtain an effect that a sufficient air bleeding effect can be obtained while stabilizing the damping force by the small holes.

[Brief description of drawings]

FIG. 1 is an enlarged half sectional view showing a rod guide portion which is a main part of a rod guide structure of a hydraulic shock absorber according to an embodiment of the present invention.

FIG. 2 is an overall sectional view showing a rod guide structure of a hydraulic shock absorber according to an embodiment of the present invention.

[Explanation of symbols]

 1 Cylinder Tube 4 Piston Rod 5 Outer Tube 7 Rod Guide 10 Annular Space (Recess) 11 Oil Seal 11d Communication Groove (Communication Passage) 71 Rod Insertion Hole 72a Notch (Communication Passage) 76 Small Hole A Upper Chamber (Inside Cylinder Tube) C reservoir chamber

Claims (1)

[Claims] 1. A rod guide, which is provided at both open end portions of a cylinder tube and an outer tube forming a reservoir chamber on the outer periphery thereof and has a rod insertion hole for guiding sliding of a piston rod at a central portion thereof, An oil seal which is provided at an upper end opening of the outer tube at an upper portion of the rod guide and slidably seals the piston rod; and on the upper surface side of the rod guide, between the rod guide and the oil seal. A recess for accumulating hydraulic fluid is formed, an air vent small hole is formed in the bottom of the rod guide that always communicates between the inside of the cylinder tube and the recess, and a recess and a reservoir chamber are formed in the upper part of the rod guide. A rod guide structure for a hydraulic shock absorber, which is characterized in that a communication passage is formed that always communicates with and.