JP2002081481A - Method of manufacturing hydraulic shock absorber containing low-pressure gas - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing an inexpensive and convenient hydraulic shock absorber containing low-pressure gas. SOLUTION: The hydraulic shock absorber is assembled in the state of extending a piston rod 1 to a maximum or pushing it into a cylinder 2 as preset without filling an operating oil, with an operating oil filler hole 3C open to the atmosphere. An empty container SV in the hydraulic shock absorber is filled with the operating oil while preventing the leakage of an air in the empty container to the outside, whereby the air in the container is compressed so that a pressure in the hydraulic shock absorber is higher than the atmosphere.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low-pressure gas-containing hydraulic shock absorber for suppressing vibration of a vehicle body such as a suspension system of an automobile, and more particularly to a method of manufacturing a low-pressure gas-containing hydraulic shock absorber.

[0002]

2. Description of the Related Art First, a conventional hydraulic shock absorber will be described with reference to FIG. In general, the hydraulic shock absorber SA mounted on the vehicle body side via the coupling portion 1B and the wheel side via the coupling member 6 is provided at the lower end in the cylinder 2 having the compression side damping valve BV and the suction valve DV disposed at the lower end. A piston guide 1A in which the extension-side damping valve PV and the check valve CV are assembled is slidably housed in the piston portion 1A, and the upper end of the cylinder 2 is guided by a rod guide 3A that guides the piston rod 1 out and out. Cover and store in outer cylinder 3. An oil seal 4 that is slidably fitted to the piston rod 1 and seals the hydraulic shock absorber is attached to the rod guide 3A.

[0003] A predetermined amount of hydraulic oil F is sealed inside the hydraulic shock absorber. On the other hand, a low pressure of several atmospheres is used to suppress the generation of bubbles in the hydraulic oil and stabilize the damping force during the buffer operation. Gas N (for example, inert nitrogen gas) is often enclosed. The upper chamber A and the lower chamber B in the cylinder 2 are both filled with hydraulic oil F, while the cylinder 2 and the outer cylinder 3
Between them, a tank chamber C filled with hydraulic oil F and a gas chamber D in which the low-pressure gas N is sealed are defined.

[0004] When assembling the hydraulic shock absorber, first, a piston having a compression damping valve BV and a suction valve DV arranged at the lower end thereof, a piston having a growth damping valve PV and a check valve CV assembled at the lower end thereof, is provided. A bottom cover 3B for covering a lower end portion of the outer cylinder 3 with a cylinder sub-assembly in which the rod 1 is slidably housed.
To be housed in the outer cylinder 3. Subsequently, a rod guide 3A for guiding the piston rod 1 so that the piston rod 1 can come and go freely.
Is inserted into the upper part of the outer cylinder 3 and the upper part of the outer cylinder 3 is closed, for example, to cover the upper end of the cylinder 2 and the upper part of the outer cylinder 3.

Next, an injection hole 3C provided in the bottom cover 3B is provided.
In the same manner as illustrated in the lower part of FIG.
A predetermined amount of hydraulic oil and an inert gas at a predetermined pressure are sealed between the cylinder 2 and the cylinder 2 and the outer cylinder 3 in a state where the pointed end of the plug 5 provided with the groove is inserted and the injection path is secured by the groove 5B. . Thereafter, the cylindrical portion 5A of the plug 5 is completely driven into the injection hole 3C of the bottom cover 3B to seal the inside of the hydraulic shock absorber. Finally, the connecting member 6 attached to the wheel side is
The hydraulic shock absorber is completed by joining to B by welding or the like.

[0006] When the piston rod 1 rises in the cylinder 2 filled with hydraulic oil, the hydraulic oil in the closed upper chamber A flows out to the lower chamber B via the extension side damping valve PV. Generates a damping force on the extension side due to the path resistance of. Hydraulic oil for the retreat volume that is insufficient due to the rise of the piston rod 1 is
The air is sucked from the tank chamber C into the lower chamber B via a suction valve DV assembled in parallel with the pressure-side damping valve BV disposed at the lower end of the cylinder 2.

Conversely, when the piston rod 1 descends in the cylinder 2, the hydraulic oil in the sealed lower chamber B passes through the check valve CV assembled in parallel with the extension damping valve PV, and the upper part of the hydraulic oil flows upward. Except for the portion replenished into the chamber A, it flows out to the tank chamber C via the compression side damping valve BV, and generates a compression side damping force due to the passage resistance at this time.

[0008]

The sealing of a low-pressure gas (for example, an inert nitrogen gas) into a hydraulic shock absorber is performed by a plug 5 provided with an injection groove 5B in an injection hole 3C provided in a bottom cover 3B.
Is inserted into the cylinder 2 and between the cylinder 2 and the outer cylinder 3 with a predetermined amount of hydraulic oil and a predetermined pressure of inert gas. It is performed by sealing the inside. Speaking of inert low-pressure gas, it can be said that nitrogen gas is violent, but the cost of the nitrogen gas itself is high, and the production of low-pressure gas-filled hydraulic shock absorbers requires nitrogen gas pressure management and equipment such as piping. Costly.

In order to suppress the generation of bubbles in the hydraulic oil and stabilize the damping force, it is not always necessary to use nitrogen gas, and the pressure of the charged gas does not need to be so high. The realization of a low-pressure gas-filled hydraulic shock absorber by a method has been desired. The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an inexpensive and simple method of manufacturing a low-pressure gas-filled hydraulic shock absorber.

[0010]

The present invention is based on the premise that "a low-pressure gas-filled hydraulic shock absorber containing a low-pressure gas of several atmospheres in order to suppress the generation of air bubbles in hydraulic oil and stabilize the damping force". Is what you do. Means taken by the present invention to solve the above problem is that the piston rod is fully extended or pushed into the cylinder by a predetermined amount without hydraulic oil, and the hydraulic oil injection hole is released to the atmosphere. The hydraulic oil is injected into the empty container of the hydraulic shock absorber while preventing the air in the empty container from leaking to the outside, thereby compressing the air in the container. Was also raised. "

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The feature of the method for manufacturing a low-pressure gas-filled hydraulic shock absorber according to the present invention is that an air-filled empty container of a hydraulic shock absorber in which an injection hole is opened to the atmosphere without hydraulic oil is provided. Is to compress the air in the container by injecting hydraulic oil while preventing the oil from escaping to the outside, and to make the pressure in the container higher than the atmospheric pressure.

Next, a method of manufacturing the hydraulic shock absorber according to the first embodiment of the present invention will be described based on the embodiment shown in FIG. The same parts as those of the prior art shown in FIG. 3 are denoted by the same reference numerals, and description of parts that are not particularly required is omitted. The tip of the plug 5 is set so that the inside and the outside of the empty container SV communicate with the injection hole 3C provided in the bottom lid 3B of the empty container SV assembled with the piston rod 1 in the most extended state through the groove 5B for injection. Is inserted, and a predetermined amount of hydraulic oil is injected using an injection jig (not shown) while preventing air in the empty container SV from escaping to the outside.

If the volume in the cylinder 2 including the injection hole 3C is Vc and the volume between the cylinder 2 and the outer cylinder 3 is Vt,
The volume V in the empty container SV when the piston rod 1 is in the most extended state.
e becomes Ve = Vc + Vt. Assuming that the volume of the hydraulic oil injected while preventing the air in the empty container SV from escaping to the outside is Vo, the volume Qe of the gas chamber in the empty container is Qe =
It is compressed to Vc + Vt-Vo.

Before injecting the hydraulic oil, the empty container S
V communicates with the atmosphere, and the pressure in the empty container SV is the atmospheric pressure (1
bar), the pressure in the empty container SV after injecting the hydraulic oil is P = Ve / Qe = (Vc + Vt) /
(Vc + Vt-Vo). This equation indicates that if the volume of the gas chamber in the empty container SV before injecting the hydraulic oil becomes 後 に after the injection of the hydraulic oil, the pressure in the container becomes twice the atmospheric pressure (2 bar). // 3, 3 times the atmospheric pressure (3
bar).

That is, instead of filling a high-cost nitrogen gas as in the conventional manufacturing method, hydraulic oil having a capacity of Vo is injected into an empty container SV having a volume of Ve assembled at atmospheric pressure. This compresses the air in the container and adjusts the pressure of the air sealed in the hydraulic shock absorber.

Assuming that the cross-sectional area of the piston rod 1 is Ar and the maximum stroke of the hydraulic shock absorber is Sm, when the piston rod 1 contracts from the maximum extension state to the maximum stroke Sm, the volume Qs of the gas chamber in the empty container SV becomes: The volume (Vc + Vt-Vo) is further reduced by the integral volume (Ar · Sm) of the piston rod 1, and Qs = Vc + Vt.
−Vo−Ar · Sm.

Therefore, there is the following restriction on the volume Vo of the working oil to be injected. The sum Vo + A of the injection amount Vo of the hydraulic oil and the integral volume (Ar · Sm) of the piston rod 1
r · Sm is the empty container S in which the piston rod 1 is in the most extended state.
If the volume in V exceeds Ve = Vc + Vt, the hydraulic shock absorber ruptures, so that Vo + Ar · Sm <Vc + Vt is a constraint. That is, the injection amount Vo of the hydraulic oil must be Vo <Vc + Vt-Ar · Sm.

As described above, the method of injecting hydraulic oil into the empty container in which the piston rod 1 is assembled in the most extended state has been described. However, as in the second embodiment of the present invention shown in FIG.
The volume in the empty container can be adjusted by pushing down the piston rod 1 into the cylinder 2. Assuming that the cross-sectional area of the piston rod 1 is Ar, the volume of the upper chamber A is Va, the volume of the lower chamber B is Vb, and the depressed length is St, the volume V in the empty container is obtained.
s is given by Vs = Va + Vb + Vc. However, the volume Va + Vb in the cylinder according to this embodiment is equal to the first volume.
Since it is equal to the volume Vc in the cylinder of the embodiment reduced by the volume of depressing the piston rod 1 (Ar · St), Vs = Vc + Vt−Ar · St.

Assuming that the volume of the working oil injected while preventing the air in the empty container from escaping to the outside is Vo, the volume Qs of the gas chamber in the empty container is Qs = Vc + Vt-Ar.St
Compressed to -Vo. Before injecting the hydraulic oil, the interior of the empty container communicates with the atmosphere, and the pressure in the empty container is equal to the atmospheric pressure (1 bar). Therefore, the pressure in the empty container after the injection of the hydraulic oil is P = Vs /Qs=(Vc+Vt-Ar.St)/
(Vc + Vt-Ar.St-Vo). That is, similarly to the first embodiment, the pressure in the container can be adjusted by the volume Vs in the empty container before the hydraulic oil is injected and the injection amount Vo of the hydraulic oil. The restrictions on the capacity Vo of the working oil to be injected are the same as those in the first embodiment, and thus the description thereof is omitted.

[0020]

As described above in detail, in the hydraulic shock absorber according to the present invention, when the piston rod is in the most extended state or in a state in which the piston rod is pushed into the cylinder by a predetermined amount, the injection hole for the hydraulic oil is supplied to the atmosphere without the hydraulic oil. The hydraulic oil is released into the empty container of the hydraulic shock absorber, while compressing the air in the container by injecting hydraulic oil while preventing the air in the empty container from escaping to the outside, so that the pressure in the container is higher than the atmospheric pressure. This is a hydraulic shock absorber containing low-pressure gas. In other words, instead of encapsulating expensive nitrogen gas as in the conventional manufacturing method, the air in the empty container is compressed by injecting hydraulic oil into the empty container assembled at atmospheric pressure, and the hydraulic buffer The gas pressure in the vessel can be adjusted.

[Brief description of the drawings]

FIG. 1 is a model diagram of a low-pressure gas-filled hydraulic shock absorber according to a first embodiment of the present invention.

FIG. 2 is a model diagram of a low-pressure gas-filled hydraulic shock absorber according to a second embodiment of the present invention.

FIG. 3 is a model diagram of a hydraulic shock absorber containing low-pressure gas of a hydraulic shock absorber according to the related art.

[Explanation of symbols]

 SV Empty container (hydraulic shock absorber) F Hydraulic oil N Air in container 1 Piston rod 2 Cylinder

Claims (1)

[Claims] 1. A hydraulic shock absorber containing a low-pressure gas of a few atmospheres in order to suppress the generation of air bubbles in hydraulic oil and stabilize the damping force. It is assembled without hydraulic oil in the pushed state, and the hydraulic oil is injected into the empty container of the hydraulic shock absorber that has been opened to the atmosphere while preventing the air in the empty container from leaking to the outside. A method for manufacturing a low-pressure gas-filled hydraulic shock absorber, characterized in that air in a container is compressed by injecting the oil to make the pressure in the hydraulic shock absorber higher than the atmospheric pressure.