JPH02217637A - Variable damping force hydraulic shock absorber - Google Patents

Abstract

PURPOSE:To provide straight damping force characteristic by furnishing No.1 communication path, which puts an inner groove in communication with one of the liquid chambers while a piston is pinched, and No.2 communication path which has a radially stretching groove carved at the end face of piston in such a way as avoiding the inner groove, and installing a variable orifice situated on the way thereof. CONSTITUTION:Under elongation stroke the working fluid in a liquid chamber A passes No.1 elongation side communication passage 2p and flows into an elongation side inner groove 2j. When flowing further, it deflects No.1 elongation side damper valve 9 and flows into an elongation side outer groove 2k from the gap formed between the valve 9 and an inner seat surface 2m. From this groove 2k it passes either of two routes and flows into a lower liquid chamber B. When following the first route the liquid opens another damper valve 10 and attains a liquid chamber B from the gap formed between this valve and an outer seat surface 2n. When following the second route the liquid flows through an intermediate chamber 2r including the groove 2k, elongation side port 30a, elongation side orifice 15d, hollow 15b in adjuster, hollow 20a, and finally attains the liquid chamber B. That is, this is a route passing No.2 elongation side communication path 30. Selection of path is performed with rotation of the adjuster 15.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a hydraulic shock absorber whose damping force characteristics can be varied and which is optimal for use in automobile suspensions.

(Prior Art) As a conventional variable damping force type hydraulic shock absorber, for example, one described in Japanese Patent Application Laid-Open No. 58-81243 is known.

In this conventional shock absorber, the inside of the cylinder is divided into a lower liquid chamber and an upper liquid chamber, and a piston consisting of a first piston part and a second piston part is provided.
The expansion side and compression side damping valves and the second expansion and compression side damping valves provided in the second piston part are arranged in series via an intermediate liquid chamber, and a switching valve provided in the intermediate liquid chamber. This allows communication between the intermediate liquid chamber and the lower liquid chamber to be selectively switched.

Therefore, in this conventional shock absorber, by switching the switching valve, a low damping force characteristic is obtained when the intermediate chamber and the lower liquid chamber are communicated with each other, and a high damping force characteristic is obtained when the communication is cut off. It was something.

(Problems to be Solved by the Invention) However, in such a conventional variable damping force hydraulic shock absorber, as described above, the first rebound/compression damping valve and the second rebound damping valve are・Since the compression side damping valve and the compression side were communicated through a common intermediate liquid chamber and the flow path was switched using a common switching valve, the damping force characteristics on the rebound side and the compression side could be controlled independently. There was a problem in that the degree of freedom in setting the damping force characteristics was low.

In addition, since the first piston part and the second piston part are divided in series through an intermediate liquid chamber, the number of components increases, and the length of the piston increases, making it difficult to limit the stroke range of the piston. There was also the problem that the basic length of the hydraulic shock absorber would have to become longer in order to widen this stroke range.

The present invention has been made by focusing on the problems of the prior art described above, and has a high degree of freedom in setting 7ffi and damping force retention.

Moreover, it is an object of the present invention to provide a variable damping force type hydraulic shock absorber that can reduce the number of parts and expand the stroke range of the piston.

(Means for Solving the Problems) In order to achieve the above-mentioned object, in the variable damping force type hydraulic shock absorber of the present invention, the inside is defined by a piston into upper and lower liquid chambers, each of which is filled with hydraulic fluid. an inner groove and an outer groove, which are at least partially arcuate and formed double inside and outside, on the end surface of the piston, on either side of the liquid chamber; an inner sheet surface formed on the outer periphery of the side gutter; an outer sheet surface formed on the outer periphery of the outer groove and protruding toward one liquid chamber side from the inner sheet direction; a first damping valve provided in contact with the seat surface; and an intermediate chamber spaced apart from the first damping valve on one side of the liquid chamber and including an outer groove formed between the first damping valve and the first damping valve. , a second damping valve provided in contact with the outer seat surface to open and close the intermediate chamber toward one liquid chamber, and a first connection communicating with the other liquid chamber across the inner groove piston. a second communication passage having a radial groove carved in the piston end face avoiding the inner groove so as to directly communicate the intermediate chamber with one liquid chamber of the end face without passing through the second damping valve; and a variable orifice provided in the middle of the second communication path.

(Function) In the variable damping force hydraulic shock absorber of the present invention, when the piston strokes to either the extension side or the overwhelming side, the hydraulic fluid in the other fluid chamber flows into the inner groove from the first communication passage, and the hydraulic shock absorber moves into the inner groove. from 1st
i The attenuation valve is opened to flow into the intermediate chamber containing the outer groove. At this time, a damping force is generated when the hydraulic fluid flows through the gap created between the first damping valve and the inner seat surface.

From this intermediate chamber, the hydraulic fluid flows into one of the liquid chambers through the following two routes.In other words, the first route opens the second damping valve from the outer groove of the intermediate chamber. The second path is a path from the intermediate chamber to the other liquid chamber via the second communication path and the variable orifice in the middle of the second communication path.

Selection of the two paths for the hydraulic fluid occurring downstream of this intermediate chamber is achieved by adjusting the flow resistance of the variable orifice. That is, when the flow resistance of the variable orifice is adjusted to be high, When the second damping valve is opened and the flow resistance of the variable orifice is lowered, the hydraulic fluid flows from the intermediate chamber to the second communication passage.

Therefore, when the No. 5 hydraulic fluid opens the second damping valve and flows, the damping force generated by the above-mentioned Liff L damping valve.

The damping force generated in the gap formed between the second damping valve and the outer seat surface is applied in series, while the damping force generated in the first damping valve is applied when the hydraulic fluid flows through the second communication path. and the damping force generated by the variable orifice are applied in series.

In addition, if a damping valve and a variable orifice are provided on the other liquid chamber side of the piston, when the piston strokes to the opposite side from the upward movement, in that case, the other liquid chamber side of the piston A damping force can be generated by both damping valves and a variable orifice provided in the damping valve.

(Example) Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

First, the configuration of the embodiment will be explained.

FIG. 1 is a sectional view showing the main parts of a variable damping force type hydraulic shock absorber according to an embodiment of the present invention, and 1 in the figure indicates a cylindrical cylinder. This cylinder 1 is defined by a slidably mounted piston 2 into an upper liquid chamber A and a lower liquid chamber B, and both chambers A.

B is filled with hydraulic fluid such as oil.

The piston 2 is attached to the tip of a piston rod 3. That is, spring 4. spring seat 5
．． washer 6, second pressure damping valve 7, washer 71. 1st
Compression side damping valve 8. Piston 2, first expansion damping valve 9. Washer 91. Second expansion damping valve 10. Washer 11. The spring seat 12 and spring 13 are sequentially installed and finally fastened with a nut 14.

More specifically, the piston 2 is provided with a piston through hole 2a in the center through which the piston rod 3 is inserted;
Further, on the upper end surface on the upper liquid chamber A side, a pressure side inner groove 2b and a pressure side outer groove 2C are formed both inside and outside. both grooves 2
As shown in FIG. 2, which is a Y-Y arrow view of the piston 2, b and 2c are formed in a hollow ring shape, and an inner seat surface 2d and an outer seat surface 2e are formed on the outer periphery of the piston 2, respectively. There is.

As shown in FIG. 1, the inner seat surface 2d is in contact with the first pressure side damping valve 8, and the pressure inner groove 2b is moved outward from the pressure side by the deflection of the first pressure side damping valve 8. It is opened and closed with respect to the side gutter 2C.

On the other hand, a second pressure-side damping valve 7 is in contact with the outer seat surface 2e, and the compression-side outer groove 20 can be opened and closed with respect to the upper liquid chamber A by bending of the second pressure-side damping valve 7. . The second pressure side damping valve 7 is biased by the spring 4 in the valve closing direction, so that the second pressure side damping valve 7 is more difficult to open than the first pressure measuring damping valve 8. ing.

Further, the pressure side inner groove 2b is communicated with the lower liquid chamber B through four first pressure side communication passages 2f (see FIG. 2) vertically bored in the piston 2.

On the other hand, the outer groove 20 is communicated with the upper liquid chamber A via the pressure side intermediate chamber 2h and the second pressure side communication passage 20. That is, a pressure side intermediate chamber 2h is provided at one location in the pressure side outer groove 20, and is formed in a groove shape in the radial direction, with one end opening in the piston through hole 2a, and separated from the pressure side inner groove 2b. ing. A hollow portion 20a is formed in the axial center of the piston rod 3, and a pressure side boat 20b is formed in the piston rod 3 in the radial direction to communicate the hollow portion 20a with the pressure I11 intermediate chamber 2h. A second pressure side communication passage 20 is formed by a communication hole 20c that is bored in the radial direction so as to communicate the hollow portion 20a and the upper liquid chamber A.

On the other hand, the lower end surface of the piston 2 on the lower liquid chamber B side has a configuration symmetrical to the upper end surface side, that is, the lower end surface has a growth side inner groove 2j and a growth side outer rF42k doubly on the inside and outside. It is formed. Both grooves 2j, 2 are formed in a hollow ring shape, as shown in FIG. It is formed.

As shown in FIG. 1, the first growth-side damping valve 9 is in contact with the inner seat surface 2m, and the growth-side inner groove 2m accommodates the deflection of the first growth-side damping valve 9. It is opened and closed with respect to the expansion side outer groove 2k.

On the other hand, a second expansion-side damping valve 10 is in contact with the outer seat surface 2n, and the expansion-side outer groove 2k can be opened and closed with respect to the lower liquid chamber B by bending of the second expansion-side damping valve 1O. It has become. In addition, the biasing force of the spring 13 is applied to the second rebound damping valve 10 in the valve closing direction, and the second rebound damping valve IO is more difficult to open than the first rebound damping valve 9. It has become.

Further, the growth-side inner groove 2j is communicated with the upper liquid chamber A through six first growth-side communication passages 2f (see FIG. 3) vertically bored in the piston 2.

On the other hand, the growth-side outer groove 2J has a growth-side intermediate chamber 2r and a second growth-side intermediate chamber 2r.
It is communicated with the lower liquid chamber B via the expansion side communication path 30.

That is, the expansion side outer groove 2. One end of the piston through hole 2a is opened at one location of j, and.

A growth-side intermediate chamber 2r formed in a groove shape in the radial direction is provided to define the growth-side inner groove 2b. The hollow portion 20a, the hollow portion 20a and the expansion side intermediate chamber 2
The second extension side communication passage 30
is formed.

Further, at the tip of the piston rod 3, an adjuster 15 as a variable orifice is provided at the upper thrust bush 16.
It is sandwiched between the lower thrust bush 17 and rotatably provided.

This adjuster 15 has an adjuster hollow portion 15 defined above and below.
a, 15b, and is formed into a cylindrical shape, and is located at a position corresponding to the pressure side boat 20b, and has a pressure side orifice hole 15c.
is formed, and a growth side orifice hole 15d is formed at a position that coincides with the growth side boat 30a, and by rotating this adjuster 15, both orifice holes 15c, ]
The cross-sectional area of the second pressure side communication passage 20 and the second extension side communication passage 30 can be changed by aligning or not aligning 5d with both boats t-20b and 30a. .

Note that the flow resistance of both the orifice holes 15c and 15d is as follows:
It is set smaller than the opening resistance of the second pressure side/growth side damping valve 7.10. Further, the adjustment element I5 is rotated by a control rod 18 provided within the piston rod 3, and this control rod 18 extends to the upper end of the piston rod 3.
Rotational force can be applied by an actuator (not shown) installed on the vehicle body attachment part.

Next, the operation of the embodiment will be explained.

(a) During the extension stroke When the piston 2 strokes to the extension side, the upper liquid chamber A
As the hydraulic pressure increases, the hydraulic fluid in the upper fluid chamber A flows into the lower fluid chamber B.
The path through which the hydraulic fluid flows at this time is as follows.

First, the hydraulic fluid in the upper liquid chamber A flows into the growth-side inner groove 2j through the first growth-side communication path 2p. And this expansion side inner groove 2. The first rebound damping valve 9 is deflected from J to flow into the rebound outer groove 2 from the gap created between the first rebound damping valve 9 and the inner seat surface 2m.

Next, the hydraulic fluid that has flowed into the expansion-side outer groove 2k flows into the lower fluid chamber B through either of the following two paths.

That is, the first path is to open the second expansion damping valve IO,
This is a path leading to the lower liquid chamber B from the gap created between the second extension damping valve 10 and the outer seat surface 2n. On the other hand, the second
The path is from the intermediate chamber 2r that includes the expansion side outer groove 2k,
This is the route from the growth side boat 308 to the growth side orifice hole 15d and from one adjuster hollow part 15 to the hollow part 20a to reach the lower liquid chamber B, that is, the path via the second growth side communication path 30.

The above two paths are selected by rotating the adjuster 15. In other words, the second expansion orifice hole 1.5d of the adjuster 15 and the expansion port 30a are not aligned. When the side communication passage 30 is shut off, the hydraulic fluid opens the second expansion side damping valve 10 and flows to the lower liquid chamber B, while aligning the expansion side orifice hole 15d with the expansion side boat 30a. In this case, the hydraulic fluid passes through the second expansion side communication path 30 and enters the lower fluid chamber B1. :iN, pass.

Therefore, when the hydraulic fluid opens the first rebound damping valve 9 and the second rebound damping valve 10 and flows, the velocity generated between the first rebound damping valve 9 and the inner seat surface 2m The damping force with the 2/3 power characteristic and the damping force with the speed 2/3 power characteristic generated in the gap formed between the second expansion side damping valve 10 and the outer seat surface 2n are added in series, and the damping force is almost linear. This is the damping force characteristic.

On the other hand, when the hydraulic fluid flows through the second expansion side communication path 30,
The damping force with the speed 2/3 characteristic generated by the first expansion side damping valve 9 and the damping force with the speed squared characteristic generated in the expansion side orifice hole 15d are applied in series, resulting in low damping that is close to a straight line. It becomes a force characteristic.

In addition, when the damping force characteristic is low in this way, when the piston speed is low, the hydraulic fluid flows through the extension side orifice hole 1.5d, but as the piston speed increases, the hydraulic fluid flows through the extension side orifice hole 15d. The resistance increases and the first expansion damping valve 9 is opened.

(b) During the compression side stroke When the piston 2 strokes toward the compression side, the operation is almost symmetrical to that in the above-mentioned expansion side stroke.

That is, when the pressure stroke is completed, the hydraulic fluid in the lower fluid chamber B becomes the first
It passes through the pressure side communication path 2f and flows into the pressure side inner groove 2b. Then, the first pressure damping valve 8 is deflected from the pressure inner groove 2b and flows into the pressure outer groove 2c from the gap created between the first pressure damping valve 8 and the inner seat surface 2d.

Next, the hydraulic fluid that has flowed into the compression side outer groove 20 flows into the upper fluid chamber A through either of the following two paths, similarly to the above-mentioned expansion side stroke.

That is, the first path is a path leading from the gap created between the second pressure side damping valve 7 and the outer seat surface 2e to the upper liquid chamber A by opening the second pressure side damping valve 7. On the other hand, the second path is from the intermediate chamber 2h including the pressure side outer groove 2e to the lower liquid chamber B via the pressure side port 20b to the pressure side orifice hole 1.5c and the regulator hollow part 15a to the communication hole 20c. In other words, this is a route that passes through the second pressure side communication path 20.

Also, in the case of this pressure side stroke, the selection of the above two routes is as follows:
This is done by rotating the adjuster 15, that is, the adjuster 1
If the pressure side orifice hole 15c of No. 5 and the pressure side boat 20b are not aligned and the second overwhelming communication passage 20 is blocked,
The hydraulic fluid opens the second pressure side damping valve 7 and flows into the upper liquid chamber A, while the hydraulic fluid flows through the pressure side orifice hole 15c and the pressure side boat 20b.
If these match, the hydraulic fluid flows through the second pressure side communication path 2.
0 to the upper liquid chamber A.

Therefore, when the hydraulic fluid opens the first pressure side damping valve 8 and the second pressure side damping valve 7 and flows, the velocity generated between the first pressure side damping valve 8 and the inner seat surface 2d is 2/3. The damping force with the multiplier characteristic and the damping force with the speed 2/3 power characteristic generated in the gap formed between the second pressure side damping valve 7 and the outer seat surface 2e are added in series, resulting in a high damping force characteristic that is close to a straight line. Become.

On the other hand, when the first hydraulic fluid flows through the second pressure side communication path 20,
The damping force of the speed 2/3 characteristic generated in the first pressure side damping valve 8 and the damping force of the speed squared characteristic generated in the compression side orifice hole 15c are applied in series, resulting in a low damping force characteristic close to a straight line. becomes.

In addition, when the damping force characteristic is set to be low as described above, the hydraulic fluid flows through the overwhelming orifice hole 15c when the piston speed is low, but as the piston speed increases, the flow resistance of the pressure side orifice hole 15c increases. , the first pressure side damping valve 8
will be opened.

As explained above, in the variable damping force hydraulic shock absorber of the embodiment, the damping valves and orifice holes that generate damping force are completely different between the compression side stroke and the compression side stroke.
The rebound damping force characteristics can be set completely independently. Therefore, it is characterized by a high degree of freedom in setting the damping force.

Furthermore, in the embodiment, a 1st and 2nd pressure side damping valve 7.8 is provided at both ends of one piston 2 to generate a damping force in the compression side stroke, and a first and second pressure side damping valve 7.8 is provided at both ends of one piston 2 to generate a damping force in the rebound side stroke.
Since two expansion side damping valves 9 and 10 are provided, the number of parts can be reduced and the configuration can be simplified compared to the conventional one that uses two pistons. As a result, the length of the piston 2 including each damping valve 7,8,9,10 can be shortened.
The advantage is that the stroke range of the piston can be widened with the same basic length of the hydraulic shock absorber.

In addition, the damping force characteristics of the embodiments are such that, in series with the damping force of the first compression and rebound damping valve 8.9, the second compression and rebound damping valve 7.10 or the compression and rebound orifice Since the characteristic is obtained by adding the damping forces of 15c and 15d, it has the characteristic that it is easy to obtain a linear damping force characteristic.

Although the embodiments of the present invention have been described above in detail with reference to the drawings, the specific configuration is not limited to these embodiments. include.

For example, in the embodiment, the present invention was applied to both the extension side and the compression side, but it may be applied only to either one.

(Effects of the Invention) As explained above, in the variable damping force type hydraulic shock absorber of the present invention, the first and second damping valves are provided on one side of one piston without using two pistons. , with fewer parts.

This has the effect of simplifying the configuration. Furthermore, like this, the first and second on one side of one piston? Since an i & damping valve is provided, if damping force is to be generated on both the rebound and compression sides, it is sufficient to provide the first and second damping valves at both ends of a single piston, respectively. ,
The piston length can be shortened compared to the conventional one, and this has the effect of widening the stroke range of the piston with the same basic length of the hydraulic shock absorber compared to the conventional one.

In addition to the above effects, in the present invention, in order to generate damping force in both the extension and compression strokes, a first damping valve and a second damping valve are provided on one side of the piston with an intermediate chamber in between, and , because a first damping valve and a second damping valve are provided on the other side with an intermediate chamber in between, and the hydraulic fluid can flow through the second communication passage and the variable orifice independently from each intermediate chamber. The damping force can be set independently on the expansion side and the compression side, resulting in an effect that the degree of freedom in setting the damping force characteristics is improved.

In addition, the damping force characteristic of the shock absorber of the present invention is a characteristic obtained by adding the damping force of the second damping valve or the variable orifice in series to the damping force of the first damping valve, so it is a linear damping force characteristic. The effect is that it is easy to obtain.

[Brief explanation of the drawing]

1 is a sectional view showing the main parts of a variable damping force type hydraulic shock absorber according to an embodiment of the present invention, FIG. The figure is a view taken along line XX in FIG. 1 showing the lower surface of the piston of the embodiment. A... Upper liquid chamber B... Lower liquid chamber ■... Cylinder 2... Piston 2a... Piston through hole (second communication path) 2b... Pressure side inner groove 2cm - Pressure side outer groove 2d...Inner seat surface 2e...Outer seat surface 2f...First pressure side communication passage 2h...Compression side intermediate chamber 2j...Elongation side inner groove 2k...Elongation side outer groove 2m... - Inner seat surface 2n... Outer seat surface 2p... First growth side communication passage 2r - - Growth side intermediate chamber 7... Second pressure side damping valve 8... First pressure side damping valve 9...・First expansion damping valve! 0...Second expansion side damping valve 15...-Adjuster (variable orifice) 15c...Compression side orifice hole 15d...Elongation side orifice hole 20...Second pressure side communication path 30...Second Extension side communication path

Claims (1)

[Scope of Claims] 1) A piston includes a cylinder whose interior is defined into upper and lower liquid chambers and is filled with hydraulic fluid, and on the side of at least one of the liquid chambers of the piston, at least An inner groove and an outer groove that are partially arcuate and formed double inside and outside, an inner sheet surface formed on the outer periphery of the inner groove, and one liquid chamber on the outer periphery of the outer groove than the inner sheet surface. an outer seat surface formed to protrude to the side; a first damping valve provided in contact with the inner seat surface to open and close the inner groove to the outer groove; and one side spaced apart from the first damping valve. A second damping valve is provided on the liquid chamber side and forms an intermediate chamber including an outer groove between the first damping valve and the second damping valve, and is provided in contact with the outer sheet surface to open and close the intermediate chamber toward one of the liquid chambers. a damping valve; a first communication passage that communicates the inner groove with the other liquid chamber across the piston; and a first communication passage that communicates the intermediate chamber directly with the one liquid chamber on the end face side without going through the second damping valve. A damping force characterized by comprising: a second communication passage having a radial groove carved in the end face of the piston avoiding the inner groove; and a variable orifice provided in the middle of the second communication passage. Variable hydraulic shock absorber.