JP3051773B2 - Hydraulic shock absorber - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a damping force adjusting means for a hydraulic shock absorber.

[0002]

2. Description of the Related Art For example, Japanese Patent Application Laid-Open No. 57-1711 discloses a hydraulic shock absorber for a vehicle in which the generated damping force changes according to driving conditions.
No. 33 is known.

[0003] In this method, a passage for a compression-side hydraulic oil and a passage for an extension-side hydraulic oil, which communicate the oil chambers on both sides with a piston which is freely slidably accommodated in a cylinder, are formed, and are interposed at these outlets. The valve closing force of the plate valve is enhanced by the magnetic force of the solenoid.

[0004]

However, in the case of this shock absorber, it is necessary to provide the piston on the extension side and the passage on the compression side, respectively, and there is a problem that the structure of the piston becomes complicated.

The present invention has been made to solve such problems, and an object of the present invention is to provide a hydraulic shock absorber having a simple structure and a wide range of adjustment of damping force.

[0006]

According to the present invention, a cylinder is provided with a slide.
Piston that is freely movable and penetrates the piston
The oil chamber on the distal side and the oil chamber on the proximal side defined by
Two parallel passages through which are provided in one of these passages
Of hydraulic fluid from the oil chamber on the proximal end to the oil chamber on the distal end
Only the valve that is allowed and the valve is
Between the solenoid that holds the passage open and the cylinder
In the structure with the oil sump provided on the side,
2 that penetrates the bottom and communicates the oil reservoir with the oil chamber on the base end side;
A parallel passage of books and one of these passages,
A pump that allows only the flow of hydraulic oil from the reservoir to the base oil chamber
Check valve and cylinder compression
The passage resistance is increased by being pushed by the hydraulic oil in accordance with the
It has a dynamic mass to increase.

[0007]

The valve provided on the piston changes the flow resistance between the oil chambers on both sides of the piston when the solenoid is excited, thereby switching the damping force characteristics in both the extension and compression directions. Further
In addition, the dynamic mass attenuates as the acceleration increases
Increase power.

[0008]

1 to 5 show an embodiment of the present invention.

As shown in FIG. 1, a piston 3 is slidably housed inside a cylinder 1 which is housed coaxially inside an outer shell 2.

A piston rod 4 is fixed to the piston 3, and the piston rod 4 projects from the cylinder 1 via a bearing 5 and an oil seal 6 so as to freely slide in the axial direction.

The inside of the cylinder 1 is defined by a piston 3 into an oil chamber 7 on the distal end side and an oil chamber 8 on the proximal end side. A port 9 is connected to the piston 3 as a passage connecting the oil chambers 7 and 8 to each other.
And 11 are formed. These ports 9 and 11 are
Always communicate with

The port 9 communicates with the oil chamber 7 through the notch 10 and the valve 13. The port 11 communicates with the oil chamber 7 via a clearance 12 set between the cylinder 1 and the piston 3.

The valve 13 is urged by a leaf spring 14 in the closing direction. Behind the valve 13, a solenoid 15 is mounted around the piston rod 4 via a pipe 16, a bobbin 17, a washer 18 and a cover 19.

The solenoid 15 is excited by energization through a cable 20 led from the outside through a hollow portion of the piston rod 4, and attracts the valve 13 made of a magnetic material against the leaf spring 14.

In order to prevent the piston rod 4 from being extended and cut off, a cylindrical lock collar 21 fitted to the outer periphery of the cover 19 is fixed to the tip of the cylinder 1 just before the piston rod 4 is at its most extended position.

On the other hand, in order to prevent the piston 3 from bottoming, a valve body 22 having a cylindrical tip is fixed to the bottom of the cylinder 1 with the tip facing the piston 3. The valve body 22 is fitted on the inner periphery of the cylindrical end of the piston 3 and prevents further penetration of the piston 3 by an oil lock.

An oil reservoir 23 filled with gas is formed in an annular gap between the cylinder 1 and the outer shell 2. And
The oil reservoir 23 communicates with the oil reservoir 8 as a passage communicating with the oil reservoir 8.
Are formed inside the valve body 22 at the bottom of the cylinder 1.

A notch 2 is formed in the opening of the port 24 on the oil chamber 8 side.
5 and the check valve 26 are provided in parallel. At the center of the valve body 22, a dynamic mass 28 is elastically supported in the oil chamber 8 via a spring 29 in opposition to the port 27. A sheet 30 for closing the port 27 is fixed to the dynamic mass 28. The dynamic mass 28 causes the seat 30 to approach the port 27 by the inertial force when the cylinder 1 accelerates in the compression direction.

The connection between the oil chambers 7 and 8 and the oil reservoir 23 is summarized in the circuit diagram of FIG.

Next, the operation will be described.

When the solenoid 15 is not excited, the valve 13 is pressed against the port 9 by the leaf spring 14. When the piston 3 operates to the extension side in this state, the hydraulic oil in the oil chamber 7 that contracts flows out to the oil chamber 8 through two paths of the notch 10 and the port 9 and the clearance 12 and the port 11. As a result, as shown in FIG.
The damping force a ₁ due to 0 and the damping force a ₂ due to the clearance 12
Is generated.

On the other hand, the operating oil corresponding to the withdrawal volume of the piston rod 4 from the cylinder 1 is supplied from the oil reservoir 23 to the check valve 26.
And flows into the oil chamber 8 through the port 27 without resistance.

If the piston 3 is made of a material having a high coefficient of thermal expansion, such as aluminum or resin, the piston 3 expands in parallel with the decrease in the viscosity of the hydraulic oil as the temperature of the hydraulic oil rises. However, since the clearance 12 is reduced, the temperature of the generated damping force can be compensated.

When the piston 3 operates in the compression direction with the solenoid 15 not excited, the hydraulic oil in the oil chamber 8 pushes and opens the valve 13 to flow into the oil chamber 7 and at the same time operates through the notch 10 and the clearance 12. Oil flows in the same direction. Thereby, as shown in FIG. 3, a combined damping force b ₁ of the notch 10 and the clearance 12 and a damping force b _{2 of the} valve 13 are generated in the piston 3.

In parallel with this, hydraulic oil corresponding to the volume of the piston rod 4 entering the cylinder 1 is supplied from the oil chamber 8 to the oil reservoir 23 through the gap between the seat 30 of the dynamic mass 29 and the port 27 and the notch 25. Leaked to Accordingly, the sheet 30 and the damping force c was synthesized damping force c ₂ generated by the damping force c ₁ and the notch 25 occurring in the gap port 27 occurs at the bottom of the cylinder 1. This damping force c is added to a combined damping force (not shown) of the piston 3 and acts as a compression-side damping force d.

As described above, when the solenoid 15 is not excited, a large damping force is generated as the piston 3 is operated in both directions of extension and compression, and a hard damping state is obtained.

On the other hand, when the solenoid 15 is energized, the valve 13 is actuated against the leaf spring 14
, And the port 9 is fully opened regardless of the operating direction of the piston 3.

As a result, as shown in FIG. 4, the damping force a when the piston 3 moves to the extension side is equal to the damping forces a ₁ and a ₂ described above, due to the pressure loss due to the pressure loss when passing through the valve 13 in FIG. It becomes a small one that combines ₃ In the same manner as in the non-excited state of the solenoid 15, the working oil corresponding to the retreated volume of the piston rod 4 from the cylinder 1 flows from the oil reservoir 23 into the oil chamber 8 without resistance.

When the piston 3 slides to the compression side, little damping force is generated in the piston 3 because the valve 13 is open, and the compression side damping force d is reduced as shown in FIG. Hydraulic oil corresponding to the intrusion volume of the piston rod 4 flowing out of the chamber 8 into the oil reservoir chamber 23 is a small one obtained by combining the damping forces c ₁ and c ₂ generated in the gap between the seat 30 and the port 27 and the notch 25.

As described above, by exciting the solenoid 15, the damping force generated in both the extension and compression directions is reduced, and a soft buffer state is obtained.

Incidentally, the dynamic mass 28 approaches the port 27 in accordance with the acceleration of the compression operation of the cylinder 1, and
The gap between the seat 30 and the port 27 is narrowed. As a result, the damping force generated by the gap between the sheet 30 and the port 27 as shown in FIG. 5 is increased to c ₁₀ from c _1, increases the compression side damping force from d accordingly to da. Due to the increase in the damping force, even in a soft buffer state in which the solenoid 15 is excited, high-frequency vibrations and the like are strongly attenuated.
Thereby, for example, the unsprung vibration of the vehicle shock absorber can be efficiently absorbed.

When the acceleration of the cylinder 1 is further increased due to a phenomenon such as resonance, the dynamic mass 28 is also greatly displaced, the seat 30 closes the port 27, and the oil chamber 8
From By limiting the outflow passage of the hydraulic oil into the oil reservoir chamber 23 notch 25 only generates a large crisis damping force equal to c ₂ in FIG.

Even if a large load is input in a soft buffer state and the shock absorber expands and contracts greatly, the cover 19 fits inside the lock collar 21 provided at the tip of the cylinder 1 against the extension load. Accordingly, with respect to a compressive load, the distal end of the piston 3 is fitted to the outside of the valve body 22 provided at the base end of the cylinder 1, thereby creating an oil lock state. There is no fear of causing.

[0034]

As described above, according to the present invention, the solenoid is excited.
By controlling the magnetic force, the damping force characteristics in both the expansion and contraction directions can be improved.
Switching between hard and soft characteristics
In addition, when the cylinder operates in the compression direction,
The mass increased the damping force as the acceleration increased
Thus, fine control of the damping force can be obtained. Therefore, various damping effects can be obtained with a simple configuration.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a hydraulic shock absorber showing an embodiment of the present invention.

FIG. 2 is a hydraulic circuit diagram.

FIG. 3 is a graph showing damping force characteristics of a solenoid in a non-excited state.

FIG. 4 is a graph showing damping force characteristics of a solenoid in an excited state.

FIG. 5 is a graph showing damping force characteristics during dynamic mass operation.

[Explanation of symbols]

 1 Cylinder 3 Piston 7,8 Oil chamber 9,11 Port 13 Valve 15 Solenoid 23 Oil reservoir

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁷ , DB name) F16F 9/46 F16F 9/50 B60G 17/08

Claims (1)

(57) [Claims] 1. A piston slidably housed in a cylinder.
And the tip defined by the piston through the piston
Parallel passages connecting the oil chamber on the side and the oil chamber on the base side
And one of these passages, from the oil chamber on the proximal end side
Valves and valves that only allow hydraulic oil to flow into the oil chamber on the tip side
And the valve is attracted by the excitation force to keep the passage open.
And the oil reservoir provided outside the cylinder.
In the structure provided, the oil penetrates the bottom of the cylinder and
Two parallel passages communicating the reservoir and the base oil chamber;
An oil chamber provided in one of these passages and located on the proximal side from the oil reservoir.
Check valve that allows only hydraulic oil to flow into
On the road, according to the increase in acceleration in the compression direction of the cylinder
To increase passage resistance when pushed by hydraulic oil
A hydraulic shock absorber comprising a mass .