JPH06671Y2 - Variable damping force type hydraulic shock absorber - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of use) The present invention relates to a hydraulic shock absorber with variable damping force, and more particularly to a mechanism for varying the damping force generated during a stroke.

(Prior Art) As a conventional damping force variable type hydraulic shock absorber, for example, one described in Japanese Patent Application Laid-Open No. 58-116213 is known.

In this conventional hydraulic shock absorber, a piston is provided with an expansion side damping valve and a compression side damping valve, and a passage is formed in parallel with both damping valves. And in this passage,
A non-return valve that opens only during compression operation and a side passage that bypasses this non-return valve are provided.In addition, a rotary valve that increases or decreases the area of this side passage to form a variable orifice is provided. Was pierced in the axial direction and engaged with a rotatable control rod.

Therefore, during the extension stroke, the hydraulic fluid in the upper liquid chamber can flow in two paths, the path through the expansion side damping valve and the path through the variable orifice and the path on the side road side. When the valve is closed, the generated damping force becomes maximum, and conversely, when the rotary valve maximizes the area of the variable orifice, the generated damping force becomes minimum.

(Problems to be solved by the invention) However, in the conventional hydraulic shock absorber as described above, since the expansion side damping valve and the variable orifice are provided in parallel, the area of the variable orifice is reduced. When the piston speed is low when the pressure is increased, that is, when the low damping force is obtained, the flow rate of the hydraulic fluid is low,
Since a large flow rate is obtained in the variable orifice, as shown in the characteristic diagram of FIG. 5, the damping force characteristic can be changed greatly as compared with the case where the variable orifice is closed. The flow velocity becomes faster, the flow rate in the variable orifice decreases, the damping force characteristic depends on the extension side damping valve, and the damping force characteristic does not change so much as compared with the case where the variable orifice is closed.

In FIG. 5, is the characteristic when the variable orifice is closed, and is the characteristic when the area of the variable orifice is maximized.

The present invention has been made by paying attention to the conventional problems as described above, and it is possible to greatly change the damping force characteristics even in the medium and high speed range, and further, to reduce the total length of the damping force type. The purpose is to provide a hydraulic shock absorber.

(Means for Solving the Problems) In order to achieve the above-mentioned object, in the present invention, the base end side is projected from the cylinder and attached to the tip end portion of the piston rod inserted into the cylinder, ,
A piston defined by a first liquid chamber in the extension stroke direction and a second liquid chamber in the compression stroke direction, and the piston formed by communicating the first liquid chamber and the second liquid chamber with each other. The extension side communication passage and the second liquid chamber side of the piston are arranged in two stages in series with an intermediate chamber formed therebetween, and the extension side communication passage is opened during the extension stroke to generate damping force upstream. A first expansion-side damping valve having a low rigidity and a second high-rigidity expansion damping valve having a downstream position, and from the intermediate chamber toward the first liquid chamber, on the way to the inner circumference of the piston or the piston. A hydraulic fluid flow path, which extends through the inner periphery of the piston to the second fluid chamber via a communication passage formed in the radial direction at the first fluid chamber side position, and is provided in the middle of the hydraulic fluid flow passage for operation. The expansion side damping force varying means for varying the generated damping force by changing the cross-sectional area of the liquid flow path is provided.

(Function) With the variable damping force type hydraulic shock absorber of the present invention, during the extension stroke,
Since the fluid pressure in the first fluid chamber rises and the fluid pressure in the second fluid chamber falls, first, the low-rigidity first extension-side damping valve is opened and the working fluid in the first fluid chamber is released. It flows through the extension side communication passage.

The second expansion-side damping valve does not necessarily open because it has high rigidity, and the hydraulic fluid that has passed through the first expansion-side damping valve flows into the intermediate chamber and then flows into the second expansion-side valve. The damping valve is opened, or it flows into the lower liquid chamber through the working fluid flow path and the expansion side damping force varying means on the way.

Therefore, the damping force generated at this time is the sum of the damping force generated by the first extension side damping valve and the damping force generated by either the second extension side damping valve or the extension side damping force varying means. Will be things.

Therefore, in order to obtain a high damping force, the cross-sectional area of the hydraulic fluid flow path of the damping force varying means may be set small, and
To reduce the damping force, the cross-sectional area of the hydraulic fluid flow path of the damping force varying means is set to be large.

Embodiment An embodiment of the present invention will be described in detail below with reference to the drawings.

First, the configuration of the embodiment will be described.

FIG. 1 is a cross-sectional view showing a hydraulic shock absorber according to an embodiment of the present invention, in which 1 denotes a cylindrical cylinder. The cylinder 1 is divided into an upper liquid chamber A and a lower liquid chamber B by a slidably mounted piston 2, and the inside thereof is filled with hydraulic fluid such as oil.

The piston 2 is attached to the tip of a piston rod 3 via a stud 4. That is, the stud 4
Is fastened to the piston rod 3 by a nut 5 while being fitted to the tip of the piston rod 3. And
A washer 6, a compression side damping valve 7, a piston body 8, a first extension side damping valve 9, a washer 10, a second extension side damping valve 11 and a washer 12 are sequentially attached to the stud 4 and fastened with a nut 13. The piston 2 is configured.

The lower end surface of the piston body 8 has a first seat surface 8a.
And the second seat surface 8b are formed in double with a step, and the first extension side damping valve 9 and the second extension side damping valve 11 are seated on each of them, so that both damping valves 9 and 11 are seated. The intermediate chamber 1 is provided in series and is located between the seat surfaces 8a and 8b.
4 are formed. The first extension side damping valve 9
The generated damping force is set low, while the generated force of the second extension side damping valve 11 is set high.

Further, the piston body 8 is provided with a pressure side communication hole 8c, a first extension side communication hole 8d, and a second extension side communication hole 8e. These will be described in detail. The pressure side communication hole 8c
Has a lower end opened to the lower liquid chamber B and an upper end formed to be openable / closable with the compression side damping valve 7.

On the other hand, the first extension side communication hole 8d is located inside the second seat surface 8b so that the upper end is opened to the upper liquid chamber A and the lower end can be opened and closed by the first extension side damping valve 9. It is open to.

Further, the lower end of the second extension side communication hole 8e has the intermediate chamber 1
4 and the upper end is opened to the annular chamber 15. The annular chamber 15 is a chamber formed in an annular shape between the piston body 8 and the stud 4.

By the way, the stud 4 has a bypass flow passage 4a formed in the lower liquid chamber B in the axial center thereof, and the bypass flow passage 4a is formed by the stud lower communication passage 4b.
And the upper liquid chamber A through the stud upper communication passage 4c.

A hollow adjuster (extension side damping force varying means) 16 is rotatably housed in the bypass flow path 4a. The adjuster 16 has an adjuster lower communication hole 16a and an adjuster upper communication hole 16b formed at positions corresponding to the stud lower communication passage 4b and the stud upper communication passage 4c. Both communication passages 4b and 4c on the side of 4 and both communication holes 16a and 16 on the side of the adjuster 16
It is possible to shift the position with respect to b to form a throttle between them, or to close both communication passages 4b and 4c.

That is, as shown in the conceptual diagram of FIG. 2, on the lower liquid chamber B side of the first expansion side damping valve 9, the path a passing from the intermediate chamber 14 to the second expansion side damping valve 11 and the intermediate chamber 14 are formed. -Second extension side communication hole 8e- Annular chamber 15- Stud lower communication passage (communication passage) 4b- Regulator lower communication hole 16a- Bypass flow passage 4a
The passage b (corresponding to the hydraulic fluid flow passage in the claims) is formed in parallel, and the generated damping force differs depending on which of the passages a and b the hydraulic fluid flows through.

A seat member 17 is fitted inside the adjuster 16, and a check valve 19 urged by a spring 18 is seated on the seat surface 17a at the upper end of the seat member 17 so that the seat member 17 A one-way valve is formed which allows only the working fluid to flow from the liquid chamber B side to the upper liquid chamber A side.

That is, as the hydraulic fluid path in the compression stroke, as shown in the conceptual diagram of FIG. 3, the path c passing through the pressure side communication hole 8c and the pressure side damping valve 7, the bypass flow path 4a, the check valve 19, and the regulator upper communication. A path d passing through the hole 16b to the stud upper communication path 4c is formed in parallel.

An operating rod 20 is connected to the adjuster 16, and a rotational force is transmitted from a motor (not shown) provided above the piston rod 3 via the operating rod 20 to rotate the adjuster 16.

Next, the operation of the embodiment will be described.

(A) When a high damping force is generated When increasing the generated damping force, the adjuster 16 is rotated to block both the communication passages 4b and 4c of the stud 4, or both the communication passages 4b and 4c and both the communication holes. The passage area formed between 16a and 16b is narrowed down.

When the extension stroke is performed in this state, the hydraulic pressure in the upper liquid chamber A rises, and the hydraulic fluid in the upper liquid chamber A passes through the first extension side communication hole 8d and passes through the first extension side damping valve. Open 9 and middle room 1
Inflow to 4.

As the path from the intermediate chamber 14, there are two paths a and b shown in FIG. 2, but in the path b, there is between the stud lower communication passage 4b and the adjuster lower communication hole 16a. Since it is blocked or squeezed small, the hydraulic fluid opens the second extension side damping valve 11 and flows into the lower liquid chamber B, and a high damping force is generated. The damping force generated at this time is the sum of the damping force generated in the first extension side damping valve 9 and the damping force generated in the second extension side damping valve 11, and this characteristic is shown in FIG. Show.

On the other hand, during the compression stroke, the hydraulic pressure in the lower liquid chamber B rises and tries to flow to the upper liquid chamber A. As the flow path at this time, there are a path c and a path d shown in FIG. 3, but in the path d, the regulator upper communication hole 16b and the stud upper communication path 4c are provided.
Since the space between and is closed or is squeezed small, the hydraulic fluid in the lower liquid chamber B flows into the upper liquid chamber A by opening the pressure side damping valve 7 from the pressure side communication hole 8c and generates a high damping force. To do.

This characteristic is shown in FIG.

(B) When a low damping force is generated When reducing the generated damping force, the adjuster 16 is rotated so that the two communication passages 4b, 4c of the stud 4 and the two communication holes 16a, 16b of the adjuster 16 are completely removed. To match.

By doing so, the hydraulic fluid can flow through the route b shown in FIG. 2 and the route d shown in FIG. 3 with almost no resistance.

Therefore, during the extension stroke, the hydraulic fluid in the upper liquid chamber A flows into the intermediate chamber 14 by opening the first extension-side damping valve 9 from the first extension-side communication hole 8d, and then through the path b, That is,
It is circulated to the lower liquid chamber B through the second extension side communication hole 8e, the annular chamber 15, the stud lower communication passage 4b, the adjuster lower communication hole 16a, and the bypass flow passage 4a. Therefore, the damping force is generated only in the first extension side damping valve 9, which is lower than that in the above case (a). This characteristic is shown in FIG.

As described above, in the case of the present embodiment, the means for varying the damping force is provided downstream of the first extension side damping valve 9,
During the extension stroke, the hydraulic fluid always passes through the first extension side damping valve 9 to generate a low damping force, and the influence of the piston speed is almost absorbed by the first extension side damping valve 9, and the second extension side communication is performed. The effect on the hole 8e side is small.

On the other hand, in the compression stroke, the hydraulic fluid in the lower fluid chamber B is transferred to the path d,
That is, the bypass flow passage 4a, the check valve 19, the adjuster upper communication hole 16b, and the stud upper communication passage 4c flow into the upper liquid chamber A through the route, and the generated damping force is also low in this case. This characteristic is shown in FIG.

As described above, in the present embodiment, the second extension side communication hole 8e and the second extension side damping valve 11 arranged in parallel, which are means for varying the damping force in the extension stroke, are provided. Since it is provided in series downstream of the first extension side damping valve 9 that generates a low damping force, when the low damping force generation state is set in the extension side stroke, it is less likely to be affected by the pitson speed, and as shown in FIG. It has a feature that it can take a large variable width in the middle and high speed range.

In addition, since the bypass passage in the extension stroke (path from the intermediate chamber 14 to the bypass passage 4a) and the bypass passage in the compression stroke (path from the bypass passage 4a to the stud upper communication passage 4b) are formed separately,・ It has the feature of increasing the degree of freedom in setting the damping force.

Furthermore, in the present embodiment, the second extension damping valve 9 is slightly spaced apart from the first extension side damping valve 9 in series with the second end on the one end surface of the piston body 8.
An expansion side damping valve 11 is provided to form an intermediate chamber 14 between the two chambers 8 and 11, and a path b, which is a hydraulic fluid flow path that connects the intermediate chamber 14 and the lower liquid chamber B, to the intermediate chamber 14 8e extending upward from the piston body 8, the annular chamber 15 on the inner periphery of the piston body 8 and the stud lower communication passage 4b formed in the stud 4 in the radial direction and the bypass flow passage 4a extending downward on the inner periphery of the pitsun body 8. By forming the path b at a position that overlaps the piston body 8 in the axial direction, the adjuster 16 that is provided in the middle of the path b and that makes the damping force characteristic variable is also formed in the piston body 8. It can be arranged from the inner circumference of the upper part to the upper part thereof.
Therefore, the member for changing the damping force is the piston 2
Since the piston 2 is not attached to the lower liquid chamber B side, the vertical dimension of the piston 2 can be shortened, and further, the overall length of the hydraulic shock absorber can be shortened.

Although the embodiment of the present invention has been described in detail above with reference to the drawings, the specific configuration of the present invention is not limited to this embodiment, and there are design changes and the like within a range not departing from the gist of the present invention. Also included in the present invention.

(Effect of the Invention) As described above, in the damping force variable type hydraulic shock absorber of the present invention, the damping force varying means is connected in series to the first extension side damping valve and the second extension side damping valve is provided. Since it is provided in parallel with the valve, even if the piston speed becomes high, the dependence on the damping force varying means side does not easily increase, and the damping force characteristic can be greatly changed even in the medium and high speed regions.

The present invention also arranges a low-rigidity first expansion-side damping valve and a high-rigidity second expansion-side damping valve in series in two stages on the second liquid chamber side of the piston, with an intermediate portion between the two. A chamber is formed, and from this intermediate chamber toward the first liquid chamber, on the way, the inner circumference of the piston is passed through the inner periphery of the piston or the communicating passage formed in the radial direction at the position closer to the first liquid chamber than the piston. An extension side damping force varying means is provided in the middle of the working fluid flow passage, which forms a working fluid flow passage to the second fluid chamber and changes the cross-sectional area of the working fluid passage to vary the generated damping force. Therefore, the total length of the piston is remarkably shortened, and the effect that the restriction on the stroke amount is relaxed and the total length of the shock absorber in the axial direction can be shortened is obtained.

[Brief description of drawings]

1 is a sectional view showing a variable damping force type hydraulic shock absorber according to an embodiment of the present invention, FIG. 2 is a conceptual view showing a flow path of hydraulic fluid in an extension stroke of the embodiment, and FIG. FIG. 4 is a conceptual diagram showing the flow path of the hydraulic fluid in the compression stroke, FIG. 4 is a graph showing the damping force characteristic of the embodiment, and FIG. 5 is a graph showing the damping force characteristic of the conventional example. A ... Upper liquid chamber B ... Lower liquid chamber C ... Reservoir chamber 1 ... Cylinder 2 ... Piston 4 ... Stud 4b ... Stud lower communication passage (communication passage) 8d ... 1st extension side communication passage (extension side communication passage) 8e ... No. 2 Expansion side communication passage (working fluid flow path) 9 ... 1st expansion side damping valve 11 ... 2nd expansion side damping valve 14 ... Intermediate chamber 16 ... Regulator (expansion side damping force varying means) 16a ... Regulator lower communication hole (Damping force changing means)

Claims (1)

[Scope of utility model registration request] 1. A base end side of a piston rod is inserted into the cylinder so that the base end side is projected from the cylinder and is attached to the tip end portion of the piston rod.
The inside of the cylinder is divided into a first liquid chamber in the extension stroke direction and a second liquid chamber in the compression stroke direction, and the piston is communicated with the first liquid chamber and the second liquid chamber. And an extension side communication passage formed on the second liquid chamber side of the piston, and an intermediate chamber is formed between the two to be arranged in two stages in series. Generating a low-rigidity first expansion-side damping bulge in the upstream position and a high-rigidity second expansion-side damping valve in the downstream position, from the intermediate chamber toward the first liquid chamber, on the way to the inner circumference of the piston. Alternatively, a working fluid flow path that reaches the second liquid chamber through the inner circumference of the piston through a communication passage that is formed in the radial direction at a position closer to the first liquid chamber than the piston, and in the middle of the working fluid flow path. And an extension-side damping force varying means that is provided to vary the cross-sectional area of the hydraulic fluid flow passage to vary the generated damping force. Damping force variable hydraulic shock absorber according to claim and.