JP4644340B2 - Manufacturing method of hydraulic shock absorber - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a low-pressure gas-filled hydraulic shock absorber that suppresses vibrations of a vehicle body, such as an automobile suspension system, and more particularly to a manufacturing method for a hydraulic shock absorber.
[0002]
[Prior art]
First, a conventional hydraulic shock absorber will be described with reference to FIG. Generally, the hydraulic shock absorber SA attached to the vehicle body side via the coupling portion 1B and the wheel side via the coupling member 6 is provided at the lower end portion in the cylinder 2 in which the compression side damping valve BV and the suction valve DV are disposed at the lower end portion. A rod guide 3A that slidably accommodates the piston rod 1 in which the expansion side damping valve PV and the check valve CV are assembled in the piston portion 1A, and that guides the piston rod 1 so that the piston rod 1 can be raised and retracted. Cover and store in outer cylinder 3. The rod guide 3A is assembled with an oil seal 4 that is slidably fitted to the piston rod 1 to seal the hydraulic shock absorber.
[0003]
While a predetermined amount of hydraulic oil F is sealed inside the hydraulic shock absorber, in order to stabilize the damping force by suppressing the generation of bubbles in the hydraulic oil during the buffer operation, the low pressure 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 the hydraulic oil F, while the tank chamber C and the low-pressure gas N filled with the hydraulic oil F are interposed between the cylinder 2 and the outer cylinder 3. A sealed gas chamber D is defined.
[0004]
When assembling the hydraulic shock absorber, first, the piston rod 1 in which the expansion side damping valve PV and the check valve CV are assembled at the lower end is installed in the cylinder 2 having the compression side damping valve BV and the suction valve DV disposed at the lower end. The cylinder subassembly accommodated slidably is accommodated in the outer cylinder 3 by being seated on a bottom lid 3B that covers the lower end of the outer cylinder 3. Subsequently, a rod guide 3A that guides the piston rod 1 so that it can freely move is inserted into the upper part of the outer cylinder 3, and the upper part of the outer cylinder 3 is tightened, for example, so that the upper end of the cylinder 2 and the upper part of the outer cylinder 3 are Cover.
[0005]
Next, in the same way as illustrated in the lower part of FIG. 1, the tip of the plug 5 provided with the injection groove 5B is inserted into the injection hole 3C provided in the bottom cover 3B to secure an injection path by the groove 5B. In this state, a predetermined amount of hydraulic oil and an inert gas having a predetermined pressure are sealed between the cylinder 2 and the cylinder 2 and the outer cylinder 3. Thereafter, the cylindrical portion 5A of the plug 5 is completely driven into the injection hole 3C of the bottom lid 3B to seal the inside of the hydraulic shock absorber. Finally, the hydraulic shock absorber is completed by connecting the connecting member 6 attached to the wheel side to the bottom lid 3B by welding or the like.
[0006]
When the piston rod 1 ascends in the cylinder 2 filled with hydraulic oil, the hydraulic oil in the sealed upper chamber A flows into the lower chamber B via the expansion side damping valve PV, and the passage resistance at this time To generate an extensional damping force. The hydraulic oil corresponding to the retraction volume that is insufficient due to the rise of the piston rod 1 is lower than the tank chamber C via the suction valve DV that is assembled in parallel with the compression side damping valve BV disposed at the lower end of the cylinder 2. Inhaled into chamber B.
[0007]
Conversely, when the piston rod 1 descends in the cylinder 2, the hydraulic fluid in the sealed lower chamber B passes through the check valve CV assembled in parallel with the expansion side damping valve PV and enters the upper chamber A. Except for the amount of replenishment, it flows out to the tank chamber C via the pressure side damping valve BV, and a pressure side damping force is generated by the passage resistance at this time.
[0008]
[Problems to be solved by the invention]
The low pressure gas (for example, inert nitrogen gas) is sealed in the hydraulic shock absorber by inserting the tip of the plug 5 provided with the injection groove 5B into the injection hole 3C provided in the bottom cover 3B, and the cylinder 2 In addition, a predetermined amount of hydraulic oil and an inert gas having a predetermined pressure are sealed between the cylinder 2 and the outer cylinder 3, and then the plug 5 is driven into the injection hole 3C to seal the inside of the hydraulic shock absorber. Speaking of inert low-pressure gas, it will be called nitrogen gas, but the cost of the nitrogen gas itself is high, and the production of a low-pressure gas-filled hydraulic shock absorber is equipped with nitrogen gas pressure management and piping, etc. It costs money.
[0009]
To stabilize the damping force to suppress the generation of air bubbles in the hydraulic oil is not necessarily a nitrogen gas and since it is no so higher filling pressure, the hydraulic pressure by the inexpensive and simple production method The realization of the shock absorber was envied. 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 for manufacturing a hydraulic shock absorber.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, the means of the present invention slidably accommodates a piston rod in a cylinder via a piston portion, and partitions the upper chamber and the lower chamber in the cylinder by the piston portion. In the hydraulic shock absorber, the upper chamber and the lower chamber communicate with each other through an extension side damping valve and a check valve provided in the piston portion, and the hydraulic shock absorber has a hydraulic oil injection hole communicating with the lower chamber . Assembling an empty container in which the piston rod is fully extended or pushed into the cylinder with no hydraulic oil in the cylinder, and then the air in the empty container is exposed to the outside through the injection hole. The air in the empty container is compressed by injecting hydraulic oil while preventing leakage, and the pressure in the empty container is made higher than the atmospheric pressure .
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Features of a method of manufacturing a hydraulic shock absorber according to the present invention, the empty containers of the hydraulic shock absorber the injection hole was opened to the atmosphere without putting hydraulic oil, while preventing the air in the empty container from escaping to the outside working The air in the container is compressed by injecting oil, and the pressure in the container is made higher than the atmospheric pressure.
That is, the hydraulic shock absorber according to the present invention, as shown in FIG. 1 or FIG. 2, accommodates the piston rod 1 in the cylinder 2 through the piston portion 1A so as to be slidable. An upper chamber A and a lower chamber B are partitioned inside, and the upper chamber A and the lower chamber B communicate with each other via an extension side damping valve PV and a check valve CV provided in the piston portion 1A. A hydraulic oil injection hole 3 </ b> C communicating with the chamber B is provided.
In the present invention, an empty container SV in which the piston rod 1 is fully extended or pushed into the cylinder 2 in a state where no hydraulic oil is put in the cylinder 2 is assembled, and then the injection hole 3C The air in the empty container SV is compressed by injecting hydraulic oil into the empty container SV while preventing the air in the empty container SV from leaking to the outside, and the pressure in the empty container SV is reduced to atmospheric pressure. It is characterized by having made it higher than.
[0012]
Next, the manufacturing method of 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 in the prior art shown in FIG. 3 are denoted by the same reference numerals, and description of parts that are not particularly necessary is omitted. The tip of the plug 5 so that the inside and outside of the empty container communicate with each other through the injection groove 5B to the injection hole 3C provided in the bottom lid 3B of the empty container SV assembled with the piston rod 1 in the fully extended state. Is inserted, and a predetermined amount of hydraulic oil is injected while preventing air in the empty container SV from escaping to the outside using an injection jig (not shown).
[0013]
Assuming that 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 Ve in the empty container SV with the piston rod 1 in the most extended state is Ve = Vc + Vt. Become. Assuming that the volume of the injected hydraulic oil is Vo while preventing the air in the empty container SV from escaping to the outside, the volume Qe of the gas chamber in the empty container is compressed to Qe = Vc + Vt−Vo.
[0014]
Before the hydraulic oil is injected, the empty container SV communicates with the atmosphere, and the pressure in the empty container SV is the same as the atmospheric pressure (1 bar). Therefore, the pressure in the empty container SV after the hydraulic oil is injected Is P = Ve / Qe = (Vc + Vt) / (Vc + Vt−Vo). If the volume of the gas chamber in the empty container SV before injecting the hydraulic oil becomes 1/2 after injecting the hydraulic oil, the pressure in the container becomes twice the atmospheric pressure (2 bar). / 3 means that it is 3 times the atmospheric pressure (3 bar).
[0015]
That is, instead of enclosing high-cost nitrogen gas as in the conventional manufacturing method, the inside of the container is injected by injecting the working oil having the capacity Vo into the empty container SV having the volume assembled at atmospheric pressure Ve. The pressure of air sealed in the hydraulic shock absorber can be adjusted.
[0016]
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 is the volume described above. Further, the intrusion volume integral (Ar · Sm) of the piston rod 1 is further reduced from (Vc + Vt−Vo), so that Qs = Vc + Vt−Vo−Ar · Sm.
[0017]
For this reason, there exists the following restrictions about the capacity | capacitance Vo of the hydraulic fluid to inject | pour. When the sum Vo + Ar · Sm of the injection amount Vo of the hydraulic oil and the intrusion volume (Ar · Sm) of the piston rod 1 exceeds the volume Ve = Vc + Vt in the empty container SV with the piston rod 1 in the most extended state, the hydraulic shock absorber Will burst, so Vo + Ar · Sm <Vc + Vt is the limiting condition. That is, the injection amount Vo of the hydraulic oil must be Vo <Vc + Vt−Ar · Sm.
[0018]
As described above, the method of injecting the hydraulic oil into the empty container assembled with the piston rod 1 in the fully 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. Assuming that the 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 push-down length is St, the volume Vs in the empty container is Vs = Va + Vb + Vt . However, since the volume Va + Vb in the cylinder of this embodiment is equal to the volume Vc in the cylinder of the first embodiment reduced by the push-down volume (Ar · St) of the piston rod 1, Vs = Vc + Vt -Ar.St.
[0019]
Assuming that the volume of the injected hydraulic oil is Vo while preventing the air in the empty container from escaping to the outside, the volume Qs of the gas chamber in the empty container is compressed to Qs = Vc + Vt−Ar · St−Vo. Before injecting the hydraulic oil, the inside of the empty container communicates with the atmosphere, and the pressure in the empty container is the same as the atmospheric pressure (1 bar), so the pressure in the empty container after injecting the hydraulic oil is P = Vs /Qs=(Vc+Vt-Ar.St)/(Vc+Vt-Ar.St-Vo). That is, as in 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 volume Vo of the hydraulic oil to be injected are the same as those in the first embodiment, and thus the description thereof is omitted.
[0020]
【The invention's effect】
In the present invention, an empty container SV in which the piston rod 1 is fully extended or pushed into a predetermined amount by assembling the cylinder 2 with no hydraulic oil in the cylinder 2 is assembled, and then the empty container SV is filled from the injection hole 3C. The air in the empty container SV is compressed by injecting hydraulic oil while preventing the air in the empty container SV from leaking to the outside, and the pressure in the empty container SV is made higher than the atmospheric pressure. Therefore, it is not necessary to enclose high-cost nitrogen gas as in the conventional manufacturing method, and it is possible to realize a hydraulic shock absorber by an inexpensive and simple manufacturing method.
[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 with a low-pressure gas in a hydraulic shock absorber according to the prior art.
[Explanation of symbols]
SV (Hydraulic shock absorber) Empty container F Hydraulic oil N Air in container 1 Piston rod 2 Cylinder

Claims (1)

A piston rod is slidably accommodated in the cylinder via a piston portion, and the upper chamber and the lower chamber are partitioned in the cylinder by the piston portion, and the upper chamber and the lower chamber are provided in the piston portion. In the hydraulic shock absorber having a hydraulic oil injection hole that communicates with the extension side damping valve and the check valve and communicates with the lower chamber, the hydraulic oil is not placed in the cylinder. assembling an empty container condition pushed maximum extension or a predetermined amount of the piston rod, and then injecting a hydraulic fluid while preventing the air in the empty container to the empty container from the injection hole from leaking to the outside The method for producing a hydraulic shock absorber according to claim 1, wherein the air in the empty container is compressed to make the pressure in the empty container higher than atmospheric pressure.

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