JPH0429887B2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Field of Application The present invention is directed to a device which is interposed between the body side and the wheel side of a vehicle in order to improve the riding comfort of the vehicle and improve the stability of rolling. This invention relates to a damping force adjustment device for a shock absorber used.

Conventional technology Shock absorbers have one end (upper end) attached to the vehicle body and the other end (lower end) attached to the wheel side, and are used to generate damping force to prevent wheel shocks received from uneven road surfaces from being transmitted to the vehicle body. It has a force generating device and a damping force adjusting device that adjusts the damping force.

A conventional damping force adjusting device for a shock absorber generally has a configuration as shown in FIG. That is, a piston c is slidably housed in a cylinder b arranged inside an outer cylinder a, and the upper end side of a hollow piston rod d whose lower end is fixed to the piston c is made to protrude above the upper end of the cylinder b. , the upper end of the piston rod d is supported by the vehicle body,
The lower end of the cylinder b is supported on the wheel side, and when the cylinder b moves up and down relative to the piston c, a hole is formed through which the pressure oil on the head side and the pressure oil on the rod side of the piston c pass through in the axial direction of the piston c. In a configuration in which a damping force is generated by moving the piston rod d back and forth, the lower end of the piston rod d has a
The lower end of the control rod g, which has a built-in rotary valve f with large and small ports arranged in the radial direction in the circumferential direction and is inserted into the hollow part of the piston rod d,
In addition to being connected to the rotary valve f, the upper end of the control rod g extends upward from the upper end of the piston rod d and is connected to an actuator h consisting of a motor, a solenoid, etc., as shown in FIG. When the actuator is driven by the sensor (position, acceleration, roll, etc.) connected to the on-board battery i and the signal from the switch j and the rotary valve f is rotated via the control rod g, the rotary valve f The provided ports of different sizes match the ports of the piston rod d, so that the damping force can be adjusted by changing the flow rate depending on the size of the port of the rotary valve f.

However, in the conventional adjustment device described above, since the actuator h is attached to the upper part of the shock absorber, the overall length of the shock absorber becomes longer, the upper part has to be mounted as a stud type, and the power source for driving the actuator h has to be taken from the battery i. In addition, there are problems such as the structure of the actuator is complicated and expensive, and because it is an electric circuit system, reliability such as cold resistance and moisture resistance is low.

Problems to be Solved by the Invention The present invention solves the problems of the conventional method by shortening the overall length of the shock absorber and operating the actuator by fluid pressure. This makes it possible to perform three-stage switching.

Means for Solving the Problems In the shock absorber damping force adjusting device of the present invention, a piston rod is movably inserted into a cylinder via a piston, and the piston partitions two oil chambers in the cylinder. In a shock absorber, the oil chamber communicates with the hollow part of the piston rod via a port, and a valve for opening and closing the port is provided in the lower part of the hollow part of the piston rod.
The valve is composed of a cylindrical outer reciprocating valve that is vertically slidable, and a cylindrical inner reciprocating valve that is inserted into the reciprocating valve so as to be vertically slidable, and the outer reciprocating valve has a piston rod. The inner reciprocating valve is provided with a plurality of ports that are opened and closed by the ports of the outer reciprocating valve, and the outer reciprocating valve is biased upwardly in the lower part of the hollow portion of the piston rod. a second spring that is smaller in elasticity than the first spring and biases the inner reciprocating valve upward; A pressure chamber for biasing the valve downward is provided, and the pressure chamber is selectively connected to a pressure fluid supply source or discharge side via an axial flow path in the piston rod. .

Embodiment As shown in FIGS. 3 and 4, in the shock absorber of the present invention, a piston rod 4 is movably inserted into a cylinder 2 via a piston, and the piston defines two oil chambers within the cylinder. The two oil chambers communicate with the hollow part of the piston rod 4 via a port, and a valve for opening and closing the port is provided in the lower part of the hollow part of the piston rod 4.

The valve is composed of a cylindrical outer reciprocating valve 7 that is vertically slidable, and a cylindrical inner reciprocating valve 8 that is inserted into the reciprocating valve 7 so as to be vertically slidable. has piston rod 4
A plurality of ports 19a, 19b, 19c, 1 which are opened and closed by ports 18a, 18b, 18c, 18d.
9d, and the inner reciprocating valve 8 has a plurality of ports 20 that are opened and closed to the ports of the outer reciprocating valve 7.
a, 20b, 20c, 20d, and 20e are provided. In the lower part of the hollow part of the piston rod 4, there is a first spring 15 that biases the outer reciprocating valve 7 upward, and a second spring 15 that has a smaller elasticity than the first spring 15 and biases the inner reciprocating valve 8 upward. a spring 16, first and second springs 15,
A pressure chamber 9 that urges the outer reciprocating valve 7 and the inner reciprocating valve 8 downward is provided opposite to the reciprocating valve 16 . The pressure chamber 9 is selectively connected via an axial passage 6 in the piston rod 4 to a source or outlet of pressure fluid. More specifically, FIGS. 3 to 5 show an embodiment of the shock absorber damping force adjusting device of the present invention, in which a piston 3 is slidably inserted into a cylinder 2 disposed inside an outer cylinder 1. In a shock absorber similar to the conventional system shown in FIG.
A pneumatic reciprocating actuator 5 that linearly reciprocates the damping force switching valve using air pressure is built into the lower end of the piston rod 4, and the action of air pressure on the actuator 5 and the exhaust are directed to the axial center of the piston rod 4. This is done through the provided flow path 6.

That is, as shown in detail in FIG. 4, the actuator 5 includes a cylindrical outer reciprocating valve 7 that is built into the lower end of the piston rod 4 and slides along the inner wall of the piston rod 4 to switch the damping force.
It operates a cylindrical inner reciprocating valve 8 that slides along the inner wall of the outer reciprocating valve 7 to switch the damping force, and a diaphragm 10 defining a pressure chamber 9 is fixed at the upper end, and A stopper 11 that determines the upper limit of the reciprocating valve 7
A hollow control rod 12 is located inside the stopper 11 and has its lower end fixed to the outer reciprocating valve 7, and a control plate 13 whose upper end is in contact with the diaphragm 10 is integrated. A control rod 14 passes through the axial center of the valve 12 and has its lower end fixed to the inner reciprocating valve 8, and the control rod 14 is interposed between the stopper 11 and the hollow control rod 12 and is constantly connected to the outside via the control rod 12. Spring 15 that acts to pull the reciprocating valve 7 upward
and a spring 16 which is interposed between the hollow control rod 12 and the control plate 13 and acts to constantly pull the inner reciprocating valve 8 upward via the control rod 14.
and the elasticity of the spring 16 is made larger than that of the spring 15 so that when air pressure acts on the pressure chamber and the diaphragm 10 expands, the spring 15 deflects faster than the spring 16. Furthermore, a cylindrical stopper 17 is fixed inside the piston rod 4 to restrict the downward movement of each of the outer and inner reciprocating valves 7 and 8.
is reciprocated between the stoppers 11 and 17 by air pressure and the elasticity of the spring 15, and the inner reciprocating valve 8 moves between the ceiling of the outer reciprocating valve 7 and the stopper 17.
Similarly, the air pressure and the elasticity of the spring 16 are used to reciprocate between the two.

The outer reciprocating valve 7 has ports 18a, 1 for a plurality of ports provided at the lower end of the piston rod 4 so as to penetrate in the radial direction at appropriate intervals in the axial direction.
Port 19a corresponding to 8b, 18c, 18d,
19b, 19c, and 19d are connected to the port 18 when the outer reciprocating valve 7 hits the stopper 17.
a, 18b, 18c, and 18d, and another port 19e is provided below the port 19a, shifted by the same amount as the movement of the outer reciprocating valve 7. Also, the inner reciprocating valve 8 has ports 20a, 20b, 20c, and 20d corresponding to the ports 19a, 19b, 19c, and 19d of the outer reciprocating valve 7 when the inner reciprocating valve 8 is at its upper limit. Ports 19a, 19b, 19c, 19d of the outer reciprocating valve 7
In addition, ports 20e and 20f are provided above and below the port 20a, shifted by the same amount as the movement of the inner reciprocating valve 8, and the port 20f has a small diameter.

Furthermore, a flow path 6 provided at the axial center of the piston rod 4 leads from the upper end of the piston rod 4 to the outside of the outer cylinder 1, and as shown in FIG. Connect to the air adjustment valve 21 and exhaust adjustment valve 22, and connect the air supply adjustment valve 21
is connected to an air supply source 23 such as a vehicle brake accumulator, and the exhaust adjustment valve 22 is connected to the atmosphere, and the pressure chamber 9 of the actuator 5 is connected to the air through the flow path 6 by opening and closing the adjustment valves 21 and 22. Make sure to pressurize or exhaust.

As configured above, the shock absorber damping force adjusting device of the present invention is configured such that when no pressure is applied to the pressure chamber 9 of the actuator 5 built into the piston rod 4, the springs 15 and 16 act to cause each reciprocating movement in the outer and inner directions. Both valves 7 and 8 reach their upper limit and the small diameter port 2 of the inner reciprocating valve 8
Only 0f corresponds to the outer ports 19a and 18a, and the damping force of the shock absorber is set to be in a hard state, taking into consideration the stability of steering.

Next, the operation of adjusting the damping force of the shock absorber to hard, medium, and soft states using the adjusting device of the present invention will be explained.

() Switching from hard to medium damping force (Fig. 6 → Fig. 7) In the hard state shown in Fig. 6, close the exhaust adjustment valve 22 shown in Fig. 5, and close the high pressure side H of the air supply adjustment valve 21. After opening and supplying air from the air supply source 23 to the pressure chamber 9 of the actuator 5, the air supply is stopped several seconds later, and at the same time, the high pressure side of the air supply adjustment valve 21 is closed to maintain the pressure chamber 9 at a high pressure. This causes the diaphragm 10 to expand and push the control plate 13 downward.
At this time, since the springs 15 and 16 have different strengths, and the spring 15 is made weaker, the spring 15 is bent and the outer reciprocating valve 7 is pushed down to the position where it contacts the stopper 17. Since the pressure chamber 9 is under high pressure, the inner reciprocating valve 8 is also pushed down against the elasticity of the spring 16 to a position where it contacts the stopper 17.
The state shown in FIG. 7 is reached. As a result, only the port 20e of the inner reciprocating valve 8 communicates with the port 19a of the outer reciprocating valve 7 and the port 18a of the piston rod 4, and all other ports of the inner reciprocating valve 8 are blocked.
The damping force is adjusted from hard to medium by the oil on the head side and rod side of the piston 3 passing through the flow path areas determined by the communicating ports 20e, 19a, and 18a.

() Switching from hard damping force to soft damping force (8th
Figure → Figure 9) In the hard state, the exhaust adjustment valve 22
Close the air supply adjustment valve 21, open the low pressure side L of the air supply adjustment valve 21, supply air from the air supply source 23 to the pressure chamber 9, and after a few seconds, stop the air supply and simultaneously close the low pressure side of the air supply adjustment valve and close the pressure chamber 9. Keep pressure low. This causes the diaphragm 10 to expand,
The control plate 13 is pushed downward, but due to the spring constants of the springs 15 and 16, the spring 15 is bent, and the control rods 12 and 14 are pushed down together, inward until the outer reciprocating valve 7 contacts the stopper 17. The reciprocating valve 8 is lowered together with the outer reciprocating valve 7 and assumes the posture shown in FIGS. 9 and 4. In this state, as shown in the figure, all ports 20a, 20b, 20c, 20d of the inner reciprocating valve 8 are connected to ports 18a, 18b, 18 of the piston rod 4.
c and 18d, the amount of oil flowing through these ports increases and the damping force becomes soft.

() Switching from medium damping force to hard damping force (Fig. 7 → Fig. 6) When switching from medium damping force to hard damping force, close the intake air adjustment valve 21 on both the high and low pressure sides and open the exhaust adjustment valve 22. . As a result, the air in the pressure chamber 9 is exhausted and the internal pressure of the pressure chamber 9 is lowered, and the bent springs 15 and 16 are both restored, and the inner reciprocating valve 8 is moved to the ceiling of the outer reciprocating valve 7, and , the outer reciprocating valve 7 moves until it hits the stopper 11, and the small diameter port 20f of the inner reciprocating valve 8
Only the piston rod 4 is in communication with the port 18a of the piston rod 4, and the oil on the head side and the rod side of the piston 3 flows through the smallest oil passage, resulting in a hard damping force.

() Switching from damping force soft to hard (9th
(Fig. 8) Open the exhaust adjustment valve 22 while keeping the high and low pressure sides of the air supply adjustment valve 21 closed. As a result, the air in the pressure chamber 9 is discharged and the internal pressure in the pressure chamber 9 is lowered, so the spring 15 which had been bent returns, and the outer reciprocating valve 7 moves together with the inner reciprocating valve 8 to the position where it contacts the stopper 11, and the As in case (), oil flows only through the small diameter port 20f of the inner reciprocating valve 8, and the damping force becomes hard.

() Switching from medium to soft damping force (Fig. 10 → Fig. 11) Open the exhaust adjustment valve 22 while keeping the high and low pressure sides of the intake air adjustment valve 21 closed, and then switch the damping force from medium to soft (Fig. 11).
Similarly to the step above, set the damping force to hard, and after a few seconds (2 to 3 seconds), exhaust adjustment valve 2
2, open the low pressure side of the air supply adjustment valve 21 at the same time as air is supplied, and after a few seconds, stop the air supply and simultaneously close the low pressure side of the air supply adjustment valve 21. The pressure chamber 9 is kept at low pressure. As a result, the diaphragm 10 expands, and the outer reciprocating valve 7 moves simultaneously with the inner reciprocating valve 8 to the position where it contacts the stopper 17, and the ports 20a, 20b, 20c, 2 of the inner reciprocating valve 8
When the oil is flowing at 0d, the damping force becomes soft.

() Switching from damping force soft to medium (Fig. 11 → Fig. 10) At the same time as supplying air, the air supply adjustment valve 21
After a few seconds, the air supply is stopped and at the same time, the high pressure side of the air supply adjustment valve 21 is closed. The exhaust adjustment valve 22 remains closed.
As a result, the pressure in the pressure chamber 9 changes from low pressure to high pressure, so the spring 16 is bent and the inner reciprocating valve 8 moves to the position where it hits the stopper 17, and oil flows only through the port 20e of the inner reciprocating valve 8. The damping force changes from soft to medium.

As described above, the damping force adjusting device of the present invention can easily adjust the damping force to three levels: hard, medium, and soft by switching the pressure chamber 9 of the actuator 5 to high pressure, low pressure, and exhaust. .

In the above embodiment, the actuator 5 is actuated by air pressure, but it goes without saying that a fluid other than air may be used.

Effect of the invention According to the present invention, the following effects can be obtained.

It is composed of an outer reciprocating valve and an inner reciprocating valve that can be slid up and down to correspond to the ports on the piston rod, so the damping force can be adjusted to three levels: hard, medium, and soft by selecting the port provided on each valve. can do.

The actuator that controls the outer and inner reciprocating valves, which are equipped with first and second springs and pressure chambers, is installed in the lower hollow part of the piston rod, compared to a conventional shock absorber that has the actuator on the vehicle body side. The total length of the shock absorber can be shortened. Similarly, the installation of the piston rod on the vehicle body side is not limited to the stud type, but also the eye type and bolt type can be used, making installation easier.

Since pressure fluid is used to supply the pressure chamber with the driving source for driving the outer and inner reciprocating valves, the structure is simpler than the conventional battery type, and it is reliable in terms of cold resistance and moisture resistance.

A flow path leading to the pressure chamber is formed inside the piston rod, which reduces weight.

[Brief explanation of drawings]

Figure 1 is a sectional view showing a conventional shock absorber damping force adjustment device, Figure 2 is a schematic diagram showing the drive mechanism of the conventional damping force adjustment device, and Figure 3 is a damping force adjustment device of the present invention. 4 is an enlarged sectional view of the damping force adjusting device of the present invention, showing the damping force soft state; FIG. 5 is a schematic diagram showing the drive mechanism of the damping force adjusting device of the present invention; FIGS. 6 to 11 are explanatory diagrams showing operating states in which the damping force adjustment device of the present invention arbitrarily adjusts the damping force between hard and soft. 2... Cylinder, 3... Piston, 4... Piston rod, 5... Actuator, 6... Channel, 7... Outer reciprocating valve, 8... Inner reciprocating valve, 9... Pressure chamber, 10... ...Diaphragm,
11... Stopper, 12, 14... Control rod, 15, 16... Spring, 17... Stopper, 18a-18d, 19a-19e, 20
a~20f...Port.

Claims (1)

[Claims] 1. A piston rod is movably inserted into a cylinder via a piston, the piston defines two oil chambers within the cylinder, the two oil chambers communicate with a hollow part of the piston rod via a port, and the piston rod is inserted into the cylinder through a piston. In the shock absorber, a valve is installed at the bottom to open and close the port.
The valve is composed of a cylindrical outer reciprocating valve that is vertically slidable, and a cylindrical inner reciprocating valve that is inserted into the reciprocating valve so as to be vertically slidable, and the outer reciprocating valve has a piston rod. The inner reciprocating valve is provided with a plurality of ports that are opened and closed by the ports of the outer reciprocating valve, and the outer reciprocating valve is biased up and down in the lower part of the hollow portion of the piston rod. a second spring that is smaller in elasticity than the first spring and biases the inner reciprocating valve upward; A shock absorber is provided with a pressure chamber that urges a valve downward, and the pressure chamber is selectively connected to a pressure fluid supply source or discharge side via an axial passage in a piston rod. Damping force adjustment device.