JPH03217314A - Damping force regulation device - Google Patents

Abstract

PURPOSE:To improve response to control of a damping force by locating a damping force regulating valve in the passage of a damper and controlling an air pressure, fed to the damper, through a pressure regulating valve controlled according to an operation state, in a device having wheels supported to a car body through a damper. CONSTITUTION:Damping force regulating valves 3 located in a passage through which working oil flows in the same direction in relation to the operation directions on both the damper compression and expansion sides are mounted on dampers 1A and 1B supporting front wheels and dampers 2A and 2B supporting rear wheels. Each damping force regulating valve 3 is formed such that when an air pressure is fed thereto from a compressor 4, a valve set load (valve opening operation characteristics) is changed and a generating damping force is changed according to the change of the valve set load. Suction and exhaust valves 5 and 6 with which a pressure regulating valve is formed are mounted so as to regulate an air pressure fed to the damping force regulating valve 3, and controlled for opening and closing by means of a control circuit 10 according to a car speed, a steering angle, and a brake state.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a damping force adjustment device for controlling the attitude of a vehicle.

(Prior art) In order to control the running attitude of a vehicle, Japanese Patent Application No. 62-274
There is a device like the one in No. 317.

This prevents the vehicle body from sinking to the left or right when the vehicle is turning.
This is suppressed by increasing the damping force of the damper that supports the wheels located on the outside of the turn, and the front of the vehicle sinks during braking by increasing the damping force of the damper that supports the front wheels. be.

(Problem to be Solved by the Invention) By the way, this device adjusts the damping force of the dampers of the left and right wheels or the front and rear wheels in accordance with the driving condition in order to suppress vehicle attitude fluctuations, that is, perform anti-roll and anti-dive control. selectively and independently regulated.

This is because the damping force can only be adjusted to the rebound or compression side. For example, in a method that adjusts the damping force on the rebound side, when turning, compression force is applied to the damper of the wheel on the outside of the turn, but the damper on the inside is applied with an expansion force. Due to the force applied, control is performed to increase only the rebound damping force of the inner damper. Therefore, in response to a change in the vehicle's attitude, it is necessary to select the damper to be controlled depending on the current driving state, and to select each damper independently.

Additionally, there are some models that can variably control the damping force on both the rebound and compression sides, but even in this case, for example, the compression side damping force is increased on the outside of the turn, and the rebound side damping force is increased on the inside. However, the fact remains that each must be controlled in a different direction, making control that much more complex.

Therefore, even if electrical control is performed using an electromagnetic damping valve or the like, complication of the control circuit and cost increase cannot be avoided.

The present invention aims to solve such problems.

(Means for Solving the Problems) Therefore, the present invention provides a suspension system that supports wheels with respect to a vehicle body through dampers, in which hydraulic oil flows in one direction for both the compression side and the rebound side. A damping force adjustment valve interposed in the passage of the damper, an adjusting means for changing the opening characteristics of the damping adjustment valve according to the supplied air pressure, a pressure adjustment valve for controlling the supplied air pressure from the air pressure source, and this pressure adjustment. and control means for controlling the valve according to the operating state.

(Function) For example, when the vehicle turns, when the air pressure supplied to the damping force adjusting valve is increased by the control means via the pressure adjusting valve, the opening pressure (set load) of the damping force adjusting valve increases accordingly. The damping force generated by the damper increases.

A compressive force is applied to the damper that supports the wheel on the outside of the turn.
An extension force is applied to the inner damper, the outer damper is compressed, and the inner damper begins to extend, but in each operation, hydraulic fluid passes through the damping force adjustment valve.

Therefore, when the damping force generated by the damping force adjustment valve increases, the damper on the outside of the turn increases the compression side damping force, and the inside damper increases the rebound side damping force, and these effectively suppress changes in the vehicle's attitude. will be done.

(Example) The example shown in Figs. 1 to 4 will be explained. In Fig. 1, LA and IB are dampers that support the front wheels, 2A,
2B is a damper that supports the rear wheel, 3 is each damper IA,
The damping force adjustment valves provided in IB and the dampers 2A and 2B are interposed in a passage through which hydraulic oil flows in the same direction for both the damper pressure side and the damper pressure side.

The damping force adjustment valve 3 is connected to a compressor 4 as an air pressure source.
When air pressure is supplied from the valve, the valve setting load (
The damping force generated is changed accordingly.

Reference numerals 5 and 6 denote an air supply valve and an exhaust valve that are electromagnetically operated, and these constitute a pressure adjustment valve for adjusting the air pressure supplied to the damping force adjustment valve 3.

Note that 7 is an accumulator for accumulating pressurized air from the compressor 4, 8 is a check valve, and 12 is a relief valve.

In the Kasho air festival with 4 compressors, there are 5 air valves.
The pressure is regulated by the exhaust valve 6 and supplied to each of the damping force adjustment valves 3 via the pneumatic circuit 9. As a control means for regulating this supply pressure according to the operating state,
A control circuit 10 is provided.

This control circuit 10 is composed of a microcomputer, etc., and receives a vehicle speed signal, a steering angle signal, a braking signal, etc. in order to detect the driving condition of the vehicle, and changes the damping force according to the driving condition determined from these. The opening and closing of the air intake valve 5 and the exhaust valve 6 are controlled by electrical signals so that the air intake valve 5 and the exhaust valve 6 are opened and closed. At the same time, the pressure in the pneumatic circuit 9 is detected by the pressure sensor 11 and input to the control circuit 10, so that the detected pressure matches the target pressure set in advance according to the operating state.
The air supply valve 5 and the exhaust valve 6 are feedback-controlled.

For example, when driving around a turn, the turning state is determined from the vehicle speed and steering angle, and the exhaust valve 6 is closed and the air supply valve 5 is opened to increase the supply pressure of the pneumatic circuit 9. When braking, the same operation is performed based on the braking signal. By increasing the supply pressure, the valve opening pressure (set load) of the damping force adjustment valve 3 is increased, the generated damping force is strengthened, and changes in the attitude of the vehicle are suppressed.

In addition, to improve running stability when driving at high speeds,
At high speeds, the pressure in the pneumatic circuit 9 can be increased to relatively increase the damping force.In this way, it is possible to not only control the attitude but also control the damping force to improve running stability and ride comfort. It has become.

Dampers IA, IB and 2A, 2B according to Figures 2 and 3
To explain the specific configuration, a piston 22 is attached to the tip of a piston rod 21 inserted into a cylinder 20, and the interior of the cylinder 20 is defined into two oil chambers 23A and 23B.

Further, an outer tube 24 is disposed concentrically on the outside of the cylinder 20, and forms an oil reservoir chamber 25 between the outer tube 24 and the cylinder 20. The piston 22 has oil chambers 23B to 23A.
There is also a check valve 26 at the bottom of the cylinder 20 that allows hydraulic oil to flow only from the oil reservoir chamber 25 to the oil chamber 2.
3. A check valve 27 is provided that allows hydraulic oil to flow only to B. A relief valve 28 is also provided at the bottom of the cylinder 20 to release hydraulic oil to the oil reservoir chamber 25 when the pressure in the oil chamber 23B exceeds a predetermined value. On the other hand, a damping force adjustment valve 3 is provided in the middle of a passage 30 connecting the oil chamber 23A and the oil reservoir chamber 25, and generates a damping force for compression side and rebound side operations by applying resistance to the flow of hydraulic oil. let

That is, when the piston 22 moves downward during pressure-side operation, the compressed hydraulic oil in the oil chamber 23B flows into the expanding oil chamber 23A via the check valve 26 of the piston 22, and is further increased by the amount of entry volume of the piston rod 21. Corresponding hydraulic oil flows out from the passage 30 to the oil reservoir chamber 25, and when the piston 22 moves upward in the expansion side operation, the piston 2
Since the second check valve 26 closes, the hydraulic oil in the oil chamber 23A to be compressed flows from the passage 30 to the oil reservoir chamber 25, and the check valve 27 at the bottom closes the hydraulic oil in the oil chamber 23A to be compressed.
Hydraulic oil is replenished from the oil reservoir chamber 25 via the
Hydraulic oil is supplied to the passage 30 for both compression side and expansion side operation.
The oil is circulated to the oil sump chamber 25 via the
The set load of the damping force adjustment valve 3 in the middle of this passage 30 (
A predetermined compression-side and rebound-side damping force is generated according to the valve opening characteristics.

The passage 30 is connected to a passage 32 provided in the bearing part 31 at the upper part of the cylinder 20, and is formed as a conduit passing vertically through the oil reservoir chamber 25, and the damping force adjustment valve 3 is attached from the outside of the outer tube. There is.

In the damping force adjustment valve 3, the inside of the valve case 35 is partitioned into an inner chamber 37 and an outer air chamber 38 by a bellows 36, and air pressure is introduced into the air chamber 38 from the air pressure circuit 9 described above. Further, three spool guides are arranged in the internal chamber 37, and a bottomed cylindrical valve spool 40 is slidably fitted on the outside of the spool guide 39, and a plunger abuts against the inner bottom surface of the valve spool 40. 41
freely slides through the center of the three Suburukaids.

Three Subur guides are formed at one end of the plunger 41, and pressure is introduced from a through hole 43 connected to the passage 30, and the valve Subur 40 is pushed out via the plunger 41 in response to this pressure.

The air pressure of the air chamber 38 is applied to the other end of the valve bouquet 40 via the bellows 36, and the plunger 41 is pushed back together with the return spring 43.

Therefore, the valve subboule 40 is displaced in accordance with these pressure balances, and moves away from the seat portion 44 to return the hydraulic oil from the through hole 43 to the oil reservoir chamber 25 from the passage 45 via the internal chamber 37. , these Barbusbourg 4
0, the plunger 41, the air chamber 38, the bellows 36, etc. constitute means for adjusting the generated damping force.

Furthermore, a free piston 4 is provided inside the piston rod 21.
A gas chamber 48 partitioned by 7 is formed, and the pressure of the oil chamber 23A is guided to the end face of the free piston 47 via a side passage 49, and the damping force adjustment valve 3 is closed and the pressure of the oil chamber 23A is guided to the end face of the free piston 47. When the load increases, the free piston 47 is displaced and absorbs the impact.

The system is constructed as described above, and its operation will be explained next.

As the piston rod 21 expands and contracts, hydraulic oil flows from the oil chamber 23A to the oil reservoir chamber 25 via the passage 30 in any direction, and also flows back from the oil reservoir chamber 25 to the oil chamber 23B.

Therefore, damping force is generated on both the expansion side and the compression side in accordance with the resistance of the damping force adjustment valve 3 interposed in the passage 30. When the air pressure from the pneumatic circuit 9 led to the air chamber 38 of the damping force adjustment valve 3 is low pressure (atmospheric pressure), the hydraulic pressure for moving the plunger 41 is determined by the spring load of the return spring 43, and the generated damping force is is in its minimum state.

For example, when a soft ride is important, such as when driving in a city, the control circuit 10 closes the intake valve 5 and opens the exhaust valve 6, thereby setting the air pressure circuit 9 to atmospheric pressure and adjusting the damping force to the minimum value. It can be done.

On the other hand, when the pressure from the pneumatic circuit 9 introduced into the air chamber 38 of the damping force adjustment valve 3 is increased, the pressure opposing the plunger 41 increases, and the hydraulic fluid required to push the valve spool 40 open increases. Pressure increases.

As shown in FIG. 4, the pressure when displacing the valve sbourg 40 via the plunger 41 is the air pressure Pv
The damping force generated increases accordingly.

The control circuit 10 closes the exhaust valve 6 and opens the air supply valve 5 according to the operating state so that the pressure in the pneumatic circuit 9 detected by the pressure sensor 11 becomes a predetermined value determined in advance depending on the operating state. , feedback control of air pressure. This air pressure is increased to control the vehicle's attitude when turning or braking, but it is also increased to improve driving stability when driving at high speeds.

When the air pressure is increased in this manner, the pressure in the air chamber 38 of the damping force adjustment valve 3 increases immediately, and the operating pressure of the plunger 41, that is, the hydraulic oil pressure in the passage 30, which opposes this increases, as well.

Therefore, in the driving state described above, the damping force is increased to correspond to the compressive force or the expansion force acting on each damper IA, IB and damper 2A, 2B, suppressing fluctuations in the vehicle body posture, and improving driving performance. It can stabilize sexuality.

In this case, for example, when driving around a corner, there is a compressive force on the inside of the corner.
An extension force acts on the outer side, but since the damping force can be increased simultaneously on both sides, the effect of suppressing posture fluctuations is higher than when only one of them is applied.

In addition, the generated damping force is determined by the pressure determined by the damping force adjustment valve 3 when operating on the middle side, and acts on the area obtained by subtracting the rod diameter from the piston diameter on the top surface of the piston 22, and when operating on the compression side, the pressure determined by the damping force adjustment valve 3 acts on the rod on the bottom surface of the piston 22. It is generated by acting on an area corresponding to the diameter, and therefore, the distribution (setting) of the damping force on the rebound side and the compression side can be freely set by changing the diameters of the piston rod 21 and cylinder 20. By the way, the piston speed during compression side operation is generally higher than when operating on the rebound side, and if the damping force is too high at this time, it will have a negative effect on ride comfort. Even when the damping force is adjusted to be higher by the damping force adjustment valve 3, when the set pressure of the overload relief valve 28 is reached during pressure side operation, the relief valve 28 opens and the hydraulic oil in the oil chamber 23B is transferred to the oil reservoir chamber 25. Therefore, the damping force does not increase any higher than that. Note that during the expansion side operation, the pressure in the oil chamber 23A increases, but the pressure in the oil chamber 23B becomes low (same pressure as the oil reservoir chamber 25), so this overload relief effect does not work on the expansion side.

Therefore, even if the rebound damping force is made large, the compression damping force does not become excessively large, and it is possible to maintain posture fluctuations and running stability while also avoiding deterioration in ride comfort.

(Effects of the Invention) As described above, according to the present invention, the pneumatic control circuit can variably control the damper's rebound and compression damping forces in response to the driving conditions, thereby suppressing vehicle body attitude fluctuations. This can contribute to improving driving stability.

In particular, the damping force on the expansion side and compression side can be controlled by using a pressure regulating valve, such as a simple control circuit with an intake valve and an exhaust valve, to control all dampers simultaneously, simplifying the control system and reducing costs. There is also the effect that it can be achieved.

[Brief explanation of drawings]

FIG. 1 is a circuit configuration diagram showing an embodiment of the present invention, FIG. 2 is a sectional view of a damper, FIG. 3 is a similar circuit configuration diagram, and FIG. 4 is a characteristic diagram of damping force. LA, IB, 2A, 2B... Damper, 3... Damping force adjustment valve, 4... Compressor, 5... Air supply valve, 6
... Exhaust valve, 9... Pneumatic circuit, 10... Control circuit, 11... Pressure sensor, 20... Jilinda, 21...
... Piston rod, 22... Piston, 23A, 2
3B...Oil chamber, 25...Oil sump chamber, 30...Passage,
36...Bellows, 38...Air chamber, 40...Valve spool, 41...Blunger. Fig. 1 Fig. 5 - Suzuki valve 11-E7'7〉sa Fig. 3 Fig. 4

Claims (1)

[Claims] In a suspension system that supports a wheel with respect to a vehicle body via a damper, a damping force adjustment valve is installed in a passage of a damper that allows hydraulic oil to flow in one direction in either the compression side or the rebound side. It includes an adjusting means for changing the opening characteristic of the damping adjusting valve according to the supplied air pressure, a pressure adjusting valve for controlling the supplied air pressure from the air pressure source, and a control means for controlling the pressure adjusting valve according to the operating state. A damping force adjustment device characterized by: