JPH0512571B2 - - Google Patents

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a hydraulic shock absorber.

(Conventional technology and its problems) In general, the damping force characteristics required for hydraulic shock absorbers installed in motorcycles, automobiles, etc. vary widely depending on driving conditions such as turning, meandering driving, sudden stopping, etc. .

Therefore, the applicant has already proposed a system in which a solenoid is housed inside the piston of a hydraulic shock absorber, and its excitation force attracts a valve made of magnetic material to adjust the valve opening pressure. 58−9537, 58−
(See Publication No. 9538).

However, in the past, there has been a demand to control the damping force characteristics not only when the hydraulic shock absorber operates on the compression side but also when it operates on the rebound side. Adjustment required two solenoids.

For this reason, the structure of the valve that can adjust the damping force on both the rebound and compression sides has become complicated, and it has been restricted to be stored in the limited space within the shock absorber, making it difficult to put it into practical use.

The present invention aims to solve the above problems.

(Means for Solving the Problems) The present invention provides a hydraulic shock absorber in which the damping force characteristics on the rebound side and the compression side are changed according to the excitation force of a solenoid disposed inside the piston. While each valve is made of magnetic material,
The piston rod that passes through the solenoid and the coil case that covers the solenoid are made of magnetic material, thereby forming a closed magnetic path that guides the magnetic flux generated in one solenoid to the rebound damping valve and the compression damping valve. It constitutes an electromagnetic control valve mechanism that variably controls the flow path connecting the oil chambers partitioned by the piston, both during expansion-side and compression-side operation.

Further, a rebound damping valve and a compression damping valve are provided in parallel with the electromagnetic control valve mechanism to open flow paths connecting the respective oil chambers partitioned by the piston against the biasing force of a spring.

(Function) This electromagnetic control valve mechanism simultaneously variably controls the damping force characteristics on the rebound and compression sides using a single solenoid, reducing the number of parts and simplifying the structure. This makes it easy to put into practical use a valve structure that can be easily accommodated in a limited space, and can adjust damping force on both the rebound and compression sides.

Furthermore, the piston is equipped with valves that open in parallel with this electromagnetic control valve mechanism in response to the urging force of the spring for the hydraulic oil on the expansion side and compression side, so that both the expansion side stroke and the compression side stroke By combining the damping force controlled by electromagnetic force and the damping force applied to the spring, desired damping force characteristics can be set over a wide range of piston speeds.

(Example) Hereinafter, an example of the present invention will be described based on the accompanying drawings.

As shown in FIG. 1, the hydraulic shock absorber 1 houses a piston 4 in an inner tube 3, defines oil chambers A and B on both sides of the piston 4, and has an outer tube outside the inner tube 3. 2 to define an oil reservoir chamber C.

A base valve 5 is installed at the proximal end of the inner tube 3.
is interposed therein, and hydraulic oil corresponding to the volume entered by the piston rod 8 flows into the oil reservoir chamber C from the oil chamber B through the base valve 5.

Outer tube 2 and inner tube 3
The base end of the piston rod 8 is connected to the axle via a bracket 7, while the tip of the piston rod 8 is connected to a bracket 9.
Outer tube 2
A suspension spring 13 is stretched between a retainer 11 fixed to the bracket 9 and a retainer 12 fitted to the bracket 9.

As also shown in FIG.
and is held between the coil cover 16.

The coil cover 16 is formed into an annular shape with an L-shaped cross section, one end of which fits into the piston rod 8 and abuts against the cushion rubber 15, the other end of which fits into the block 32, and the solenoid 17 is housed inside the coil cover 16.

An annular pilot seat 69 and a valve guide 33 are fixed to the piston rod 8.

The pilot seat 69 has a substantially L-shaped cross section, and its upper end is secured by a circlip 70.

The valve guide 33 has a substantially U-shaped cross section, and has an inner peripheral portion 33 that fits into the pilot seat 69.
L, and an outer circumferential portion 33J that protrudes downward concentrically with the inner circumferential portion 33L, and this outer circumferential portion 33J is brought into contact with the block 32.

A port 35 is formed in the coil cover 16, a notch 36 is formed in the outer circumference 33J of the valve guide 33, a port 37 is formed in the nut 68,
Thereby, a communication path D that communicates oil chambers A and B with each other.
will be established.

The pilot valve (rebound damping valve) 39 is formed into an annular shape and is slidably fitted onto the piston rod 8 via a pilot guide 73, with a coil spring 40 interposed between the pilot guide 73 and the nut 68. This allows pilot valve 3
9 is urged by the coil spring 40 and seats on the pilot seat 69 and the end face of the valve guide inner circumferential portion 33L.

The non-return valve (compression side damping valve) 38 is formed into an annular shape and is slidably housed inside the outer circumference 33J of the valve guide 33.
A leaf spring 4 is installed between the valve guide 33 and the valve guide 33.
Interpose 1. As a result, the non-return valve 38
is biased by the leaf spring 41 and the block 3
It is seated on the end face of 2.

The end faces of the pilot seat 69 and the inner circumferential portion 33L of the valve guide, on which the pilot valve 39 is seated, and the end face of the block 32, on which the non-return valve 38 is seated, are all arranged on the same plane, so that the pilot valve 39 and the non-return valve 38 are seated on each other to block the communication path D.

The solenoid 17 conducts electricity from the earth spring 21 to the negative terminal 22 through the piston 8, while it connects the positive terminal 2 through the coil terminal 23 and the center wire 24 housed in the shaft hole 75 of the piston rod 8.
5, and an exciting current is sent from a control unit (not shown) according to the operating conditions.

While the valve guide 33 is formed of a non-magnetic material,
The piston rod 8, the pilot guide 70, the pilot valve 39, the non-return valve 38, the block 32, and the coil cover 16 are all made of magnetic material, as shown by hatching in the interrupted plane of the figure, and the lines of magnetic force generated from the solenoid 17 are Creates a closed magnetic path guided by magnetic material. As a result, the density of the magnetic force passing through the pilot valve 39 and the non-return valve 38 is increased, and the excitation force causes them to attract each other.

A plurality of through holes 45 are formed in the block 32,
A communication path E is provided that communicates the oil chambers A and B with each other.
An annular main valve (growth side damping valve) 46 for opening and closing the communication path E is interposed at the opening of the through hole 45,
A coil spring 47 is interposed between the main valve 46 and the nut 68.

The piston rod 8 is formed with a plurality of through holes 76 that open into the shaft hole 75, and a solenoid 17 is formed in the piston rod 8.
A gap 78 is defined between the valve guide 33 and the pilot guide 70 in the bobbin 77 that accommodates the shaft hole 75, the through hole 76, and the gap 78.
A communication path F that communicates the oil chambers A and B with each other is constituted by this.

An enlarged diameter portion 75a is formed at the lower end of the shaft hole 75, and an annular valve seat 81 is press-fitted and fixed into this enlarged diameter portion 75a. A center valve (compression side damping valve) 82 is housed in the shaft hole 75 and is seated on a valve seat 81 .

A coil spring 86 is interposed between the center valve 82 and the terminal guide 85, so that the center valve 82 is pressed against the valve seat 81, and the terminal guide 85 is pressed against the center line 81.
4 and the coil terminal 23 in a crimped position. A small diameter portion 87 is formed at the lower end of the terminal guide 85, into which the coil spring 86 is inserted, and a recessed portion 88 is formed in the center valve 82, into which the lower end of the coil spring 86 is inserted.

The terminal guide 85 is designed to seal the side of the shaft hole 75 in which the center line 24 is accommodated.

In addition, the non-return valve 38 has an orifice 4.
8 to always communicate oil chambers A and B in a small area.

Fig. 3 shows the piston 4 in a hydraulic circuit diagram, including the pilot valve 39 and the non-return valve 3.
8 has a common solenoid, and the main valve 46 and the pilot valve 39 open to the extension side hydraulic oil, while the center valve 82 and the non-return valve 38 open to the pressure side hydraulic oil.

Figure 4 shows orifice 48 and non-return valve 3.
8, Center valve 82, Pilot valve 3
9. This shows the damping force characteristics provided by each main valve 46 independently. First, in the extension stroke,
In addition to the damping force applied by the orifice 48 (dotted line), the damping force applied by the pilot valve 39 (solid line) is continuously variably controlled, and the main valve 46 also provides a damping force (1 The damping force of the main valve 46 is set so that it becomes effective after the pilot valve 39 is fully opened.

On the other hand, in the compression side stroke, in addition to the damping force applied to the orifice 48 (dotted line), the damping force of the non-return valve 38 (solid line) is continuously variably controlled.
Furthermore, the center valve 82 applies a damping force (dotted chain line) that is primarily proportional to the piston speed.

Since the pilot valve 39 has a small degree of freedom in setting the damping force, cavitation is likely to occur due to over-throttling, and without the center valve 82, it was difficult to adjust the desired damping force in the shaded area in the figure.

Therefore, the damping force applied by the center valve 82 is set to be effective from a region where the piston speed is low, thereby improving the cavitation limit of the rear throttle.

As a result, the overall damping force characteristics of the hydraulic shock absorber 1 are as follows:
As shown in FIG. 5, continuous control is possible over a wide range, and accurate adjustments can be made depending on the driving conditions.

In addition, the pilot valve 39 and the non-return valve 38 are
are arranged facing each other, the number of parts is reduced, the structure is simplified and the size is reduced, and as a result, it is possible to sufficiently accommodate the limited space within the hydraulic shock absorber 1. , making practical application easier.

(Effects of the Invention) As described above, the present invention provides a piston with an electromagnetic control valve mechanism that changes the damping force characteristics on the expansion side and compression side using a single solenoid, and also provides a spring in parallel with this electromagnetic control valve mechanism. Since the rebound-side damping valve and the compression-side damping valve, which open in opposition to the biasing force, are arranged in succession, it is possible to continuously control the damping force on the rebound and compression sides over a wide range, allowing accurate control according to the driving conditions. Furthermore, the relatively simple structure that uses only one solenoid makes it easy to put into practical use a valve structure that can adjust both the expansion side and the compression side.

[Brief explanation of the drawing]

Fig. 1 is an overall sectional view of a hydraulic shock absorber according to an embodiment of the present invention, Fig. 2 is an enlarged sectional view of the piston section, and Fig. 3 is a hydraulic circuit diagram disposed in the piston. FIG. 4 is a diagram showing the damping force characteristics of each valve, and FIG. 5 is a diagram showing the overall damping force characteristics of the hydraulic shock absorber. DESCRIPTION OF SYMBOLS 1... Hydraulic shock absorber, 4... Piston, 5... Base valve, 8... Piston rod, 16... Coil cover, 17... Solenoid, 32... Block, 38...
Non-return valve, 39...Pilot valve, 4
6...Main valve, 82...Center valve, A,
B...Oil chamber, C...Oil sump chamber.

Claims (1)

[Claims] 1. In a hydraulic shock absorber that changes the damping force characteristics on the rebound side and the compression side according to the excitation force of a solenoid arranged inside the piston, the rebound side damping valve and the compression side damping valve are each made of a magnetic material, and A piston rod that passes through the solenoid and a coil cover that covers the solenoid are made of magnetic material to form a closed magnetic path that guides the magnetic flux generated in the solenoid to the expansion damping valve and the compression damping valve.
An electromagnetic control valve mechanism is provided that variably controls the damping force characteristics on the rebound and compression sides using a single solenoid, and in parallel with this electromagnetic control valve mechanism, a recovery side damping valve and a compression side damping valve having damping force characteristics corresponding to the biasing force of the spring are installed. A hydraulic shock absorber characterized in that each damping valve is provided.