JP2000234642A - Damping force adjusting type hydraulic shock absorber for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a compact hydraulic shock absorber improved in assembly workability, maintainance ability and practicability in the hydraulic shock absorber of simple constitution with damping force controllable in extension/ pressure sides by a single solenoid valve. SOLUTION: In this damping force adjusting type hydraulic shock absorber 10 for a vehicle, a circulation passage 24 allowing operating oil from an oil chamber 13A in a side of a piston rod 14 to flow and an oil sump 27 compensating an oil amount change in a cylinder 11 according to in/out movement of the piston rod 14 are arranged in an external peripheral part of the cylinder 11, one ends of an oil chamber 13B of a piston side, circulation passage 24, and the oil sump 27 are blocked by a piece 28, first/second communication paths 31, 32 are formed in the piece 28, and a solenoid valve 40 is built in.

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 type vehicle hydraulic shock absorber.

[0002]

2. Description of the Related Art Conventionally, the damping force in both the extension side and the compression side stroke is
Hydraulic shock absorbers that can be adjusted by a single solenoid valve and have a simple configuration include those described in JP-A-64-47693, JP-A-3-25044, and JP-A-5-164177.

[0003]

However, Japanese Patent Application Laid-Open No. Sho 64
JP-A-47693 discloses an electromagnetic valve that is provided so as to be wrapped around one end of the cylinder itself, and the assemblability of the cylinder is poor. In addition, when performing maintenance on the solenoid valve, it is necessary to incise the cylinder itself, resulting in poor maintainability.

[0004] Also, JP-A-3-25044, JP-A-5-16
Since the solenoid valve described in Japanese Patent No. 4177 is provided with the solenoid valve separated from the cylinder, it is necessary to extend a hydraulic pipe between the cylinder and the solenoid valve. Also, the assemblability and maintainability are poor.

SUMMARY OF THE INVENTION An object of the present invention is to provide a hydraulic shock absorber which has a simple structure, in which a single solenoid valve can control the damping force on the extension side and the compression side, and which is compact, has good assemblability and maintenance, and has high practicality. It is to provide a shock absorber.

[0006]

According to the present invention, a piston is slidably inserted into a cylinder to define oil chambers on both sides of the piston, and a piston rod connected to the piston is connected to the cylinder. A first valve which is slidably supported at one end side and allows the piston to allow only the flow of hydraulic oil from the oil chamber on the piston side to the oil chamber on the piston rod side is provided on the outer peripheral portion of the cylinder. A circulation passage through which hydraulic oil flows from the oil chamber, and an oil reservoir that compensates for changes in the amount of oil in the cylinder due to the ingress and egress of the piston rod are arranged. One end of the oil chamber on the piston side, the circulation passage, and one end of the oil reservoir is a piece. In this piece, a first communication path connected to the oil reservoir and a second communication path connected to the circulation path are formed, and an electromagnetic valve is incorporated in the piece. The second communication path is connected via the electromagnetic valve. Connected to the first communication passage, the first communication passage It is connected to the oil chamber on the piston side via a second valve that allows only the flow of hydraulic oil from the oil reservoir to the oil chamber on the piston side, and the solenoid valve is operated so that the damping force can be adjusted according to the running state of the vehicle It is made to be done.

According to a second aspect of the present invention, in the first aspect of the present invention, the piece is further provided with an opening hole which opens to the side, and a solenoid valve is removably fitted in the opening hole. It is intended to be mounted.

According to a third aspect of the present invention, in the first or second aspect of the present invention, the circulation passage and the oil reservoir are each defined by a steel tube coaxial with a cylinder. It was made.

[0009]

According to the first aspect of the present invention, the following operations are provided. Since the solenoid valve is incorporated in the piece provided in the cylinder,
It is more compact than those that enclose the solenoid valve in the cylinder itself or connect it to the cylinder via hydraulic piping.
The ease of assembly and maintenance can be improved.

According to the second aspect of the present invention, the following operations are provided. Since the solenoid valve is removably fitted in the side opening hole of the piece, assemblability and maintainability can be further improved.

According to the third aspect of the present invention, the following operations are provided. Since each of the steel pipes coaxial with the cylinder defines the circulation passage and the oil reservoir on the outer periphery of the cylinder, the size can be further reduced.

[0012]

FIG. 1 is a schematic view showing a hydraulic shock absorber,
FIG. 2 is a sectional view showing a main part of FIG.

As shown in FIG. 1, a hydraulic shock absorber 10 has a piston 11 slidably inserted into a cylinder 11 to define oil chambers 13A and 13B on both sides of the piston 12.
2 is slidably supported by a rod guide 15 provided at one end of the cylinder 11. 16 is an oil seal, 17 is an end plate, 18
Is a cap.

The piston 12 has an oil chamber 13A and an oil chamber 13B.
A first valve that allows only the flow of hydraulic oil from the oil chamber 13B on the side of the piston 12 to the oil chamber 13A on the side of the piston rod 14 and blocks the flow in the opposite direction is provided. 22 is provided in the channel 21.

An intermediate cylinder 23 made of, for example, a steel pipe is coaxially arranged on the outer periphery of the cylinder 11 with a predetermined gap therebetween, and a circulation passage 24 is defined between the cylinder 11 and the intermediate cylinder 23. The circulation passage 24 is connected to the oil chamber 13 </ b> A on the side of the piston rod 14 via a communication passage 25 formed in the rod guide 15 at the upper end of the cylinder 11.

An outer cylinder 26 made of, for example, a steel pipe is coaxially arranged on the outer periphery of the intermediate cylinder 23 with a predetermined gap therebetween, and an oil reservoir 27 is defined between the intermediate cylinder 23 and the outer cylinder 26. Oil reservoir 2
7 compensates for a change in the amount of oil in the cylinder 11 due to the ingress and egress of the piston rod 14. The upper space of the oil reservoir 27 is a gas chamber, and the gas pressure can be adjusted by the pneumatic supply plug 100.

The above-mentioned cap 18 is attached to the upper end of the cylinder 11, the intermediate cylinder 23 and the outer cylinder 26, and the piece 28 is attached to the lower end. A bottom piece 29 is interposed between the cylinder 11 and the piece 28.

That is, the oil chamber 13B on the side of the piston 12, the circulation passage 24, and one end of the oil reservoir 27 are closed by the piece 28. As shown in FIG. 2, a first communication passage 31 connected to the oil reservoir 27 and a second communication passage 32 connected to the circulation passage 24 are formed in the piece 28.
An electromagnetic valve 40 is incorporated. The second communication path 32 is connected to the first communication path 31 via the electromagnetic valve 40, and the first communication path 3
Reference numeral 1 denotes an oil chamber 13 on the side of the piston 12 via a second valve 33 that allows only the flow of hydraulic oil from the oil reservoir 27 to the oil chamber 13B on the side of the piston 12 and prevents the flow in the opposite direction.
It is connected to B. The second valve 33 is the bottom piece 2
Nine channels 34 are provided.

The piece 28 is provided with an opening 35 that opens laterally, and the solenoid valve 40 is removably fitted in the opening 35. The solenoid valve 40 has an opening hole 35.
Are fitted in a liquid-tight manner and screwed.

The solenoid valve 40 has an outer box 41 screwed to the piece 28 and an inner box 42 screwed to the outer box 41.
The outer case 41 includes a solenoid 43 and a needle 44 driven by the solenoid 43. The inner box 42 has a cylindrical shape, and has a large-diameter communication port 42A and a small-diameter communication port 4A.
2B. The inner box 42 has a ring-shaped stopper 45 screwed from the second communication passage 32 and a back pressure adjuster 46 fitted from the outer box 41 and fixed by the outer box 41.
And a spool 47 movable between the stopper 45 and the adjuster 46.

The spool 47 is provided with a positive pressure chamber 47B on the side of the second communication passage 32 of the throttle passage 47A provided in the central partition.
A back pressure chamber 47C is formed on the adjuster 46 side, and the positive pressure chamber 4
The discharge port 47D is opened in the diameter direction of the discharge port 4B.
7D can be conducted to the communication port 42A of the inner box 42, and the stopper 45 is provided by a spring 48 provided in the back pressure chamber 47C.
And is repelled in a direction in which the end of the movement stroke can be regulated. The direction in which the spool 47 abuts against the stopper 45 is set such that the discharge port 47 </ b> D
The area A (the valve opening area of the solenoid valve 40) that conducts to A is set to zero. The solenoid valve 40 generates a small damping force when the valve opening area A is large, and generates a large damping force when the valve opening area A is small.

The back pressure adjuster 46 is provided with a throttle hole 46A directly communicating with the back pressure chamber 47C of the spool 47.
4, a flow path 46B is provided that communicates the throttle hole 46A adjusted by the needle 44 with the communication port 42B of the inner box 42.

The solenoid valve 40 has a spring 49A for springing the needle 44 in the direction to close the throttle hole 46A and a spring 49B for springing the needle 44 in the direction to open the throttle hole 46A, and both when the solenoid 43 is turned off (demagnetized). The needle 44 is set to the fully open position under the balance of the spring force of
Is turned on (excited), the degree of restriction of the restriction hole 46A by the needle 44 can be increased as the excitation current value increases.

Accordingly, in the solenoid valve 40, the hydraulic pressure P ₁ of the positive pressure chamber 47B of the spool 47 and the hydraulic pressure P _{2 of the} back pressure chamber 47C
Is in the state of P ₁ > P ₂ due to the restricting action of the restricting flow path 47A, if the setting of the solenoid 43 is OFF or the low exciting current value, the needle 44 does not restrict the restricting hole 46A at all or almost, relative pressure P ₁ of the positive pressure chamber 47B of 47,
It does not increase any or very little oil pressure P ₂ in the back pressure chamber 47C. Therefore, the differential pressure between P ₁ and P ₂ maintains P ₁ > P ₂ and the spool 4
7 moves only by this pressure difference compressing the spring 48 against the spring force of the spring 48, and the discharge port 47D has a large conduction area A (valve opening area) with the communication port 42A. To reduce the damping force.

[0025] On the other hand, the higher the excitation current value of the solenoid 43, the needle 44 is squeezed increase the throttle hole 46A, with respect to P ₁ of the positive pressure chamber 47B of the spool 47, the back pressure chamber 47C
P ₂ is increased of approaches to the P _1. Thus, next to the pressure difference P ₁ and P ₂ is small, the spool 47 will shall be mainly positioning by the spring force of the spring 48 by reduction of the pressure difference, the discharge port 47D are conductive area A of the communication port 42A And the damping force by the solenoid valve 40 is increased as a result. This tendency to increase the damping force increases in proportion to the degree to which the needle 44 narrows the throttle hole 46A, and thus increases in proportion to the increase in the exciting current value of the solenoid 43. That is, in the solenoid valve 40, the exciting current of the solenoid 43 is controlled according to the output of a vehicle speed sensor, an acceleration sensor, and the like for detecting the driving condition of the vehicle. When it is desired to increase the current value and reduce the damping force at the time of low-speed running, it can be used to reduce the exciting current value.

Hereinafter, the operation of the hydraulic shock absorber 10 will be described. (A) Extension Side Stroke In the extension side stroke of the hydraulic shock absorber 10, the first valve 22 of the piston 12 is closed, and oil in the oil chamber 13 </ b> A on the side of the piston rod 14 flows from the circulation passage 24 to the second communication passage 32. , The spool 47 in the solenoid valve 40 is pushed open against the spring 48 and flows into the first communication passage 31.

On the other hand, the oil chamber 13B is
The oil corresponding to the retreated volume of the piston rod 14 is supplied through the second valve 33 through the communication passage 31.

Therefore, the damping force in the extension side stroke is controlled by the solenoid valve 4.
It is determined by the valve opening characteristic of the spool 47 determined by the spring 48 within 0.

At this time, when the solenoid 43 of the solenoid valve 40 is energized and excited, the spool 47 is driven in accordance with the exciting current value.
(The conductive area A between the discharge port 47D and the communication port 42A) can be controlled to adjust the optimal damping force according to the operation state.

(B) Pressure side stroke In the pressure side stroke of the hydraulic shock absorber 10, the second valve 33 of the bottom piece 29 is closed, and the oil in the oil chamber 13B passes through the first valve 22 of the piston 12 to the oil chamber 13A. The spool 47 passes through the second communication passage 32 from the circulation passage 24 and pushes the spool 47 in the solenoid valve 40 open against the spring 48 to flow into the first communication passage 31. Then, of the oil that has reached the first communication passage 31, the oil corresponding to the intrusion volume of the piston rod 14 flows into the oil reservoir 27.

Therefore, the damping force in the compression stroke is also determined by the valve opening characteristics of the spool 47 determined by the spring 48 in the solenoid valve 40, as in the expansion stroke.

Further, at this time, when the solenoid 43 of the solenoid valve 40 is energized and energized in the same manner as in the extension side stroke, the valve opening area of the spool 47 is controlled in accordance with the value of the energizing current, and the optimum value is determined in accordance with the operation state. It can be adjusted to an appropriate damping force.

Therefore, according to the present embodiment, the following operations are provided. Since the solenoid valve 40 is incorporated in the piece 28 provided on the cylinder 11, the solenoid valve 40 is more compact and assembling than those which are wrapped around the cylinder 11 itself or connected to the cylinder 11 via hydraulic piping. Performance and maintainability can be improved.

Since the solenoid valve 40 is removably fitted in the side opening hole 35 of the piece 28, the assembling property and the maintenance property can be further improved.

The steel pipes coaxial with the cylinder 11 define the circulation passage 24 and the oil storage chamber 27 on the outer periphery of the cylinder 11, respectively.

The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration of the present invention is not limited to this embodiment, and the design can be changed without departing from the scope of the present invention. The present invention is also included in the present invention.

[0037]

As described above, according to the present invention, in a hydraulic shock absorber having a simple structure capable of controlling the damping force on the extension side and the compression side by a single solenoid valve, compactness, assemblability and maintainability are achieved. A good and practical hydraulic shock absorber can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a hydraulic shock absorber.

FIG. 2 is a sectional view showing a main part of FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Hydraulic shock absorber 11 Cylinder 12 Piston 13A, 13B Oil chamber 14 Piston rod 22 1st valve 23 Intermediate cylinder 24 Circulation passage 26 Outer cylinder 27 Oil storage chamber 28 Piece 31 First communication path 32 Second communication path 33 Second valve 40 solenoid valve

Claims (3)

[Claims] An oil chamber is defined on both sides of a piston by slidably inserting a piston into a cylinder, and a piston rod connected to the piston is slidably supported at one end of the cylinder. A first valve that allows only the flow of hydraulic oil from the oil chamber of the piston rod to the oil chamber on the piston rod side, and a circulation passage for flowing hydraulic oil from the oil chamber on the piston rod side to the outer periphery of the cylinder; An oil sump that compensates for the change in oil amount in the cylinder due to the entry and exit of the cylinder is arranged. The oil chamber on the piston side, the circulation passage, and one end of the oil sump are closed by a piece, and this piece is connected to the oil sump. A first communication path and a second communication path connected to the circulation path are formed, and an electromagnetic valve is incorporated. The second communication path is connected to the first communication path via the electromagnetic valve, and the first communication path is an oil reservoir. Oil from the chamber to the oil chamber on the piston side A solenoid valve that is connected to an oil chamber on the piston side through a second valve that allows only the displacement, and the solenoid valve is operated so that the damping force can be adjusted according to the running state of the vehicle. Shock absorber. 2. The damping force adjustable vehicle hydraulic shock absorber according to claim 1, wherein the piece has an opening hole that opens to the side, and a solenoid valve is removably fitted in the opening hole. 3. The hydraulic shock absorber according to claim 1, wherein the circulation passage and the oil reservoir are each defined by a steel pipe coaxial with a cylinder.