JPH0448344Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Field of Application) The present invention relates to a single cylinder hydraulic shock absorber in which a cylinder defines an oil chamber and a gas chamber.

(Prior Art) Conventionally, as a single-cylinder hydraulic shock absorber in which an oil chamber and a gas chamber are defined in a cylinder, for example, the Japanese Patent Publication No. 61-7393
As described in the above publication, there is known a system that changes the damping force during compression depending on the stroke position of the piston and also compensates for changes in oil temperature.

This hydraulic shock absorber separates the inside of the cylinder into an oil chamber and a gas chamber by a movable barrier, screws the base end to the movable barrier, and inserts a tapered rod into an orifice formed on the fixed barrier. The damping force generated is changed by changing the flow path area of the orifice as the orifice slides.

(Problem to be solved by the invention) In the above-mentioned hydraulic shock absorber, the proximal end of the long taper rod is screwed to the movable barrier, and this taper rod is inserted into the orifice. In some cases, the axis of the taper rod and the axis of the orifice do not match, and the taper rod is inserted in a fallen state, making it impossible to obtain a stable damping force. Furthermore, since the taper rod is fixed to the movable barrier, the initial load is only one step regardless of the stroke position of the piston, making it impossible to obtain extremely fine changes in damping force.

(Means for Solving the Problems) In order to solve the above problems, the present invention divides the oil chamber into an upper oil chamber and a lower oil chamber by a separator fixed inside the cylinder, and A cylindrical outer slider with an orifice that communicates between the inside and outside is slidably inserted into the part and biased toward the upper oil chamber by a return spring, and a blow valve is slid inside this outer slider. The outer slider is biased toward the upper end side by a valve spring that can be inserted freely and whose set load changes depending on the position of the outer slider, and a check valve is inserted by forming an extension oil hole in the separator.

(Function) The blow valve is pushed down by the hydraulic oil that enters the outer slider from the upper oil chamber through the orifice between it and the blow valve, and its upper end moves away from the inner top of the outer slider, causing the hydraulic oil in the upper oil chamber to flow. flows into the lower oil chamber, but when the stroke of the piston is small and the lower end of the piston rod does not push the outer slider, the outer slider responds to the pressure of the hydraulic oil in the upper oil chamber, which is pressurized as the piston descends. This increases the set load when the upper end of the blow valve separates from the inner top of the outer slider, so the damping force generated changes depending on the speed of the piston. Also, when the lower end of the piston rod comes into contact with the upper end of the outer slider, the lowering of the piston rod directly mechanically lowers the outer slider and pushes down the internal blow valve, so the set load on the blow valve changes according to the stroke position. As a result, the change in damping force that occurs depending on the stroke position of the piston becomes even larger.

(Example) An example of the present invention will be described below based on the accompanying drawings.

FIG. 1 is a sectional view of a hydraulic shock absorber according to the present invention;
FIGS. 2 and 3 are cross-sectional views each illustrating the operating state of the same shock absorber, and FIG. 4 is a diagram showing the compression side damping force characteristics of the same shock absorber.

The upper and lower ends of the cylinder 1 of the hydraulic shock absorber are closed with caps 2 and 3, and a separator 4 is fixed within the cylinder 1 by caulking. This separator 4 is formed by fixing a partition member 6 to the inner periphery of a ring member 5.

A concave groove 7 is formed on the outer circumference of the separator 4, and the proximal circumferential edge of the bladder 8 is fitted into the concave groove 7, so that the proximal circumferential edge of the bladder 8 is connected to the inner circumferential surface of the cylinder 1. The bladder 8 is held tightly and defines within the cylinder 1 an oil chamber S1 and a gas chamber S2 filled with inert gas under pressure. Furthermore, separator 4
A deformation prevention case 9 facing the inside of the bladder 8 is attached to the inner periphery of the ring member 5 .

In addition, the oil chamber S1 in the cylinder 1 is connected to a separator 4.
Since the oil chamber S3 is divided into an upper oil chamber S3 and a lower oil chamber S4 as an in-bladder oil chamber, the barrier member 6 forming the separator 4 has a central hole 11 in the center for arranging a position-dependent mechanism. The deformation prevention case 9 is formed with a plurality of oil holes 12 that communicate between the inside and outside.

Furthermore, a piston rod 15 is inserted into the upper oil chamber S3 from above via a rod guide 14, and a piston 16 equipped with a valve mechanism that slides on the inner peripheral surface of the cylinder 1 is attached to the lower end of the piston rod 15.

An upper oil chamber S3 is provided in the center hole 11 of the separator 4 according to the stroke position of the piston 15.
A position dependent mechanism 17 that changes the area of the oil passage connecting the lower oil chamber S4 and the lower oil chamber S4 is provided.

This position-dependent mechanism 17 includes a cylindrical outer slider 18 whose upper end is closed and whose lower end is open, which is slidably inserted into the center hole 11 of the separator 4 . An orifice 19 is formed to communicate between the inside and outside, and a spring receiving part 18a which also serves as a stopper is formed at the lower part of the outer slider 18.
A return spring 20 is interposed between a and the bottom of the deformation prevention case 9 to urge the outer slider 18 upward.

A cylindrical blow valve 21 with a small diameter portion at the top is slidably inserted into the inner circumference of the outer slider 18, and a space between the lower end surface of the blow valve 21 and the bottom of the deformation prevention case 9 is inserted into the inner circumference of the outer slider 18. A valve spring 22 is interposed to urge the blow valve 21 toward the inner top of the outer slider 18.

Further, a plurality of extension side oil holes 24 are formed in the partition wall member 6 forming the separator 4, and the extension side oil holes 24 are formed in the partition wall member 6 forming the separator 4.
A check valve 25 is disposed within the valve body 4, and the check valve 25 is biased downward by a spring bearing ring 26 and a check valve spring 27 interposed therebetween.

The operation of the hydraulic shock absorber configured as described above will be explained below.

First, when the hydraulic shock absorber is fully extended, the first
As shown in the figure, when the piston 16 moves from the upper limit to the compression stroke and the piston rod 15 descends with the piston 16, the piston rod 15 enters the upper oil chamber S3, so the entry volume of the piston rod 15 increases. A considerable amount of hydraulic oil enters from the orifice 19 of the outer slider 18 into the annular oil passage 28 formed between the inner circumference of the outer slider 18 and the outer circumference of the small diameter portion of the blow valve 21;
When the pressure of this hydraulic oil becomes greater than the biasing force of the valve spring 22, the blow valve 21 is pushed down against the biasing force of the valve spring 22.

As a result, a gap is created between the upper end of the blow valve 21 and the inner top of the outer slider 18, so that the hydraulic oil that has entered the outer slider 18 passes through the center hole 21a of the blow valve 21 to the lower oil. Since it flows into the chamber S4 and further into the bladder 8 through the oil hole 12 of the deformation prevention case 9, the bladder 8 expands downward by a volume corresponding to the volume of entry of the piston rod 15. The damping force generated at this time is determined by the amount of gap (opening) between the upper end of the blow valve 21 and the inner top of the outer slider 18.

When the piston 16 descends with the lower end of the piston rod 15 not in contact with the upper end of the outer slider 18, the outer slider 18 is moved into the lower upper oil chamber of the piston 16 by the pressure receiving area corresponding to its diameter. As the outer slider 18 descends, the blow valve 21 is pushed down against the valve spring 22, and the blow valve 21 is pushed down against the valve spring 22.
As the set load increases, the damping force increases in accordance with the speed of the piston 16, and the damping force characteristics generated at this time are as shown, for example, by line a in FIG. 4.

When the piston rod 15 further descends from this state and the lower end of the piston rod 15 comes into contact with the upper end of the outer slider 18 as shown in FIG. 18 is directly mechanically pushed down by the piston rod 15 against the return spring 20, and as the outer slider 18 descends, the blow valve 21 is pushed down against the valve spring 22. Since the set load increases, the damping force increases depending on the stroke position of the piston 16, and the damping force characteristic generated at this time is, for example, the fourth
This is shown by line b in the figure.

When the piston rod 15 moves to the extension stroke after descending to the lower limit position as shown in FIG. The check valve 25 opens and the hydraulic oil in the lower oil chamber S4 returns to the upper oil chamber S3 through the expansion oil hole 24, causing the hydraulic oil in the bladder 8 to deform. Since the oil flows into the lower oil chamber S4 through the oil hole 12 of the prevention case 9, the piston rod 1
The bladder 8 is lifted upward by a volume corresponding to the volume of the gas 5 that has escaped, and the capacity of the gas chamber S2 is increased.
In addition, the outer slider 18 and the blow valve 2
1 moves upward following the rise of the piston rod 15 by the restoring forces of the return spring 20 and valve spring 22, respectively, and returns to the state shown in FIG.

(Effect of the invention) As explained above, according to the invention, the separator fixed inside the cylinder divides the oil chamber into an upper oil chamber and a lower oil chamber, and the central part of the separator has communication between the inside and outside. A cylindrical outer slider with an orifice formed therein is slidably inserted into the outer slider and urged toward the upper oil chamber by a return spring, and a blow valve is slidably inserted into the outer slider. Since the upper end of the outer slider is biased by a valve spring whose set load changes depending on the position of the slider, if the lower end of the piston rod does not come into contact with the outer slider when the piston rod descends during the compression stroke, the upper oil chamber The outer slider descends according to the pressure of the hydraulic oil, increasing the set load on the blow valve, and the damping force generated changes according to the speed of the piston. When the lower end of the piston rod comes into contact with the upper end of the outer slider, The lowering of the piston rod directly mechanically lowers the outer slider and increases the set load on the blow valve, which further increases the change in damping force that occurs depending on the stroke position of the piston, resulting in a stable damping force. At the same time, fine damping force changes can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a hydraulic shock absorber according to the present invention;
FIGS. 2 and 3 are sectional views each illustrating the operating state of the shock absorber, and FIG. 4 is a diagram showing the compression side damping force characteristics of the shock absorber. In addition, in the drawing, 1 is a cylinder, 4 is a separator,
6 is a partition member, 7 is a groove, 8 is a bladder, 9 is a deformation prevention case, 11 is a center hole, 15 is a piston rod, 16 is a piston, 17 is a position dependent mechanism, 18
is an outer slider, 19 is an orifice, 20 is a return spring, 21 is a blow valve, 22
is the valve spring, 24 is the extension side oil hole, 25 is the check valve, S1 is the oil chamber, S2 is the gas chamber, S
3 is an upper oil chamber, and S4 is a lower oil chamber.

Claims (1)

[Scope of utility model registration request] In a single cylinder hydraulic shock absorber that defines an oil chamber and a gas chamber in a cylinder, a separator is fixed in the cylinder to divide the oil chamber into an upper oil chamber and a lower oil chamber, and the separator is A cylindrical outer slider is slidably inserted into the center and biased toward the upper oil chamber by a return spring, and an orifice is provided at the upper end of the outer slider to communicate between the inside and outside. A blow valve is slidably inserted inside, and the upper end of the outer slider is biased by a valve spring whose set load changes depending on the position of the outer slider, and an oil hole on the extension side is formed in the separator. , a position-dependent hydraulic shock absorber characterized in that a check valve is installed in the oil hole on the extension side.