JPS61211547A - Assembling method for hydraulic shock-absorber - Google Patents

Abstract

PURPOSE:To improve the assembling performance by inserting a sliding member into a path formed from the tip of a piston rod while communicating with a bypath to separate between the bypath and the temperature sensitive chamber while choking the open end of the temperature sensitive chamber with non- compressive packing and securing the packing with a nut. CONSTITUTION:A bush 27 is inserted slidably near to an orifice 24 on a path 2 to separate a temperature sensitive chamber 30 encapsulating a liquid L expansionable upon detection of temperature variation. The open end of small diameter section of said chamber 30 is choked oil-tightly with a disc packing 31 and a cap nut 29 for tightening said packing 31 to the small diameter section 31. Since the pressure of encapsulated liquid wall never vary when tightening the packing, while the liquid is flowed over through the weight of packing when assembling, mixing of air is blocked.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method of assembling a hydraulic shock absorber which compensates for gradual temperature changes.

(Prior Art) In a hydraulic shock absorber, the hydraulic oil is repeatedly compressed violently due to the reciprocating movement of the piston as the vehicle travels, and the oil temperature gradually rises.

When the viscosity of the hydraulic oil decreases due to an increase in oil temperature, the flow resistance of the pulp and orifice that exerts the damping force decreases, resulting in a decrease in the damping force.

As a result, the damping characteristics at the time the vehicle starts running cannot be maintained, leading to deterioration in ride comfort and handling as the driving time progresses. In order to prevent such fluctuations in damping force due to changes in oil temperature, shock absorbers equipped with various temperature compensation mechanisms have been proposed.

For example, JP-A-51-3937-0 and JP-A-54-4
No. 4166 describes a 17th filter in which a liquid is sealed in a sensitive chamber formed separately from the hydraulic oil chambers above and below the piston, and the expansion of this liquid due to temperature changes is used to create a bypass passage that detours around the top and bottom of the piston. A method for controlling the aperture area of the is disclosed.

According to this, a needle is attached to a piston that slides according to the expansion of the liquid, and the amount of insertion of the needle into the oriice is increased in proportion to the displacement of the piston to squeeze the oriice.
The reduction in viscosity is compensated for by the reduction in the opening area, and the damping force can always be kept the same.

(Problems to be Solved by the Invention) However, none of the devices disclosed in these documents mentions the detailed mechanism such as the control of the amount of liquid sealed in the sealed sensitive chamber, and it is difficult to actually use them. In the case of mass-produced products, it is extremely difficult to avoid variations in the damping characteristics because the initial opening degree of the oriice varies depending on the amount of sealed liquid.

There were also considerable problems with assembly, and no effort had been made to efficiently produce under well-controlled conditions.

The present invention was proposed in order to solve these problems, and aims to enable accurate filling of liquid into a sensitive room and to improve assembly efficiency.

(Means for Solving the Problems) Therefore, the present invention provides a bypass passage that short-circuits the upper and lower oil chambers of the piston, and an orifice is interposed in this bypass passage, while changing the temperature of the hydraulic oil in the oil chamber. In the hydraulic shock absorber, the bypass passage is formed in the piston rod, and the hydraulic shock absorber is provided with a sliding member that narrows the opening area of the oriice in accordance with the expansion of the liquid. , the 17th passage is connected to the bypass passage and formed from the tip of the piston rod.
The sliding member that squeezes the filter is inserted to a predetermined position to separate the bypass passage and the sensitive chamber, while the sensitive chamber is filled with liquid and the opening at the other end is filled with liquid using an incompressible plate-shaped packing. The piston rod is closed while overflowing, and the gasket is tightened and fixed from the outside with a nut that is screwed onto the piston rod.

(Function) Therefore, a predetermined amount of liquid can be accurately filled in the sensitive chamber, and air can also be prevented from entering.

(Example) Embodiments of the present invention will be described below based on the drawings.

FIG. 1 shows an embodiment in which the oil sump tank is placed separately and the present invention is applied to a 1-unit unit, where 1 is a shilling,
2 is a piston slidably inserted into the cylinder 1, 3 is a piston rod, 4 is a suspension spring interposed between the piston rod 3 and the cylinder 1, and 5A and 5B are the ends of the piston rod 3 and the cylinder 1. This is a mounting bracket installed on the

The inside of the cylinder 1 is divided into an upper oil chamber 10 and a lower oil chamber 11 by a piston 2, and a pipe 12 is connected to the lower oil chamber 11.
The oil reservoir chamber 14 of the tank 13 communicates with the oil storage chamber 14 through the tank 13. Therefore, as the piston rod 3 enters, a portion of the hydraulic oil in the lower oil chamber 11 (the volume of the piston rod entering) flows into the oil reservoir chamber 14 of the tank 13 while pushing the piston 15.

The piston 2 is inserted into the small diameter tip n16 of the piston rod 3 together with the valve stopper 17, and the piston nut 18
Fixed by A valve 20 that opens the through hole 19 of the piston 2 during pressure side operation is biased in the valve closing direction by a spring 21.

As is clear from FIG. 2, a passage 22 is formed in the axial center of the small diameter portion 16 of the piston rod 3 from the axial end direction. Branch road 2 that opens to the outer circumferential side of 3
3 and the 17th pipe 24 communicate with each other, thereby forming a bypass passage 25 that bypasses the piston 2.

Therefore, a portion of the hydraulic oil passes through this bypass passage 25 during either expansion side or compression side operation, and a predetermined damping force is exerted by the Oriais throttle during this passage.

In order to compensate for the temperature of this damping force, a bushing 27 is inserted in the vicinity of the orifice 24 of the passage 22 through an O-ring 28 in an oil-tight manner and slidably. A sensitive chamber 30 containing a liquid L (which may be the same type of oil as the hydraulic oil) that expands upon sensing the pressure is provided.

The sensitive chamber 30 has a disc-shaped gasket 3 at the open end of the small diameter portion 16.
1 and a cap nut 2 which is screwed onto the small diameter portion 16 and tightened.
9, it is oil-tightly closed.

In this case, in order to accurately determine the amount of sealed liquid and to prevent the bushing 27 from moving due to changes in internal pressure due to tightening, the packing 31 is made of incompressible or similar material, such as copper packing or resin packing. Alternatively, use a hard rubber gasket or the like to attach this to the opening end part 32.
A cap nut 29 that is fitted into the cap nut 29 and has an oil wetting hole 33 from the outside.
Make sure to tighten it. Then, the adjustment of the enclosed liquid is as follows.
As shown in FIGS. 3A and 3B, first, before assembling the piston 2, a thin rod-shaped jig M is inserted into the passageway 2 through the orifice 24.
Insert the O-ring 2 so that the tip protrudes from the O-ring 2.
8 fitted into the bushing 27 from the open end of the passage 22.
Push it in until it hits.

Next, the jig M is removed and the piston assembly is fitted onto the piston rod 3, but even when the jig M is pulled out, the bushing 27 is strongly held in its position by the compression pressure caused by the tightness of the O-ring 28.

After assembling the piston 2, when the liquid is poured into the sensitive chamber 30 all at once and the gasket 31 is placed on it, the excess liquid will overflow due to the weight of the gasket 31, and will be filled in when the gasket 31 reaches the correct seating position. The liquid level is exactly the specified amount.

When the cap nut 29 is tightened from above, the sensitive chamber 30 becomes completely airtight.Moreover, since the gasket 31 is made of an incompressible material, no deformation occurs, so the internal pressure increases as the nut 29 is tightened. does not change, and therefore the bushing 27 remains exactly at its initial position. Note that the oil wetting hole 33 provided in the cap nut 29 allows liquid and air existing between the seal 31 and the cap nut 29 to escape during this tightening, so that deformation of the seal 31 is prevented by containing these.

In the above, when the temperature of the hydraulic oil in the upper and lower oil chambers io and ii rises due to the operation of the shock absorber, that is, the expansion and contraction of the piston rod 3, the temperature of the liquid in the sensitive chamber 30 also rises in almost the same way. do.

Therefore, the bush 27, which was initially located near the seventeenth hole 24, moves so as to reduce the opening area of the orifice 24 in proportion to the expansion of the enclosed liquid reservoir.

A portion of the hydraulic fluid flows through this first stage on both the rebound and compression sides.
7 It passes through the orifice 24 and flows into the upper oil chamber 10 or the lower oil chamber 11, and at this time it is subjected to orifice restriction and generates a predetermined damping force. As the oil temperature increases, the viscosity decreases, so if the opening area of the orifice 24 remains the same, the damping force will also decrease. However, since the orifice 24 is throttled through the bush 27 as the oil temperature rises, it is possible to prevent the fluid reduction resistance from decreasing and to maintain a constant damping force at all times.

Next, the embodiment shown in FIG. 4 will be explained. In this case, no pilot part 32 is particularly provided on the end face of the piston rod 3, the flat end face is closed with a plate-shaped packing 31, and a cap nut 29 is fitted. It is something that

Further, in the embodiment shown in FIG. 5, a screw hole is machined in the upper part of the spigot part 32, and a screw 29' is fitted into this threaded part instead of the cap nut 29 to fix the gasket 31. be.

In either case, the gasket 31 can be easily tightened without changing the internal pressure of the sensitive chamber 30.

Although the above-mentioned embodiment shows an example in which the present invention is applied to a shock absorber for a tank-separate tie pipe, it is obvious that the present invention can be applied to other hydraulic shock absorbers.

(Effects of the Invention) As explained above, according to the present invention, the open end of the sensitive chamber is left open with a non-compressible packing, and this packing is fixed with a cap nut, so that tightening of the packing is sometimes difficult. There is no pressure fluctuation of the liquid sealed inside, and fluctuations in the initial position of the bushing as a sliding member relative to the oriice can be prevented, and variations in liquid reduction characteristics can be avoided.

Furthermore, since the weight of the gasket causes the liquid to become opaque during assembly, it is possible to prevent air from entering the liquid, thereby stabilizing the damping characteristics especially at high temperatures.

The enlarged cross-sectional view of the tongue part and FIGS. 3A and 3B are explanatory diagrams showing an assembly method when filling a liquid in a sensitive chamber.

FIGS. 4 and 5 are sectional views showing essential parts of other embodiments, respectively.

DESCRIPTION OF SYMBOLS 1... Schilling, 2... Piston, 3... Piston rod, 10.11... Upper and lower oil chambers, 16... Piston rod small diameter part, 22... Passage, 23... Branch passage, 24...orifice, 25...bypass passage,
27... Sliding member (bush), 29... Bag nut, 30... Sensitive chamber, 31... Packing, 32...
Part of the intro.

Claims (1)

[Claims] A bypass passage is provided to short-circuit the upper and lower oil chambers of the piston.
An orifice is interposed in this bypass passage, and a sensitive chamber is formed in which a liquid that expands and contracts as the temperature of the hydraulic oil in the oil chamber changes, and the opening area of the orifice is narrowed in response to the expansion of this liquid. In the hydraulic shock absorber provided with a moving member, the bypass passage is formed in the piston rod, and a sliding member for narrowing the orifice is inserted into the passage formed from the tip of the piston rod to a predetermined position, communicating with the bypass passage. After filling the sensitive chamber with liquid, the opening at the other end is closed with an incompressible plate-shaped packing while allowing the filled liquid to overflow, and this packing is inserted into the piston from the outside. A method of assembling a hydraulic shock absorber characterized by tightening and fixing it with a nut screwed onto a rod.