JPS62137212A - Suspension device for automobile - Google Patents

Abstract

PURPOSE:To appropriately control the damping force of a damper section, by providing such an arrangement that the loading condition of a vehicle is discriminated in accordance with a variation in the pressure of a pressure chamber in an air spring, and the damping force of the damper section is controlled in accordance with the result of the discrimination. CONSTITUTION:In accordance with variations in load, a detected ground clearance Sh is delivered to a control unit 20 from a ground clearance sensor 22 to actuate directionally control valves 10, 13, 14 so that the pressures of pressure chambers in air springs in suspension units 2L. 2R are changed to change the vehicle level. Variations in pressure is detected by a pressure switch 24, and therefore, for example, a signal Sp indicating that the air pressure exceeds a predetermined value is delivered to a control unit 20, and then the control unit 20 discriminates the loading condition of the vehicle in accordance with the signal Sp and delivers a control signal Sc to electrically driven actuators 26L, 26R so that the damping forces of the damper sections may be changed. With this arrangement it is possible to control the damper sections, appropriately.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an automobile suspension device that controls relative movement between a vehicle body and an axle in an automobile.

(Conventional technology) In a vehicle, a suspension is installed between the vehicle body and the axle.
The unit is arranged to reduce the transmission of impact from the road surface, which the axle receives, to the vehicle body. As a self-formation of such a suspension unit, for example, as described in Japanese Utility Model Application Laid-Open No. 59-79407, an air spring part that utilizes compressive elasticity of air as a spring means and a mechanism for damping its vibrations are used. An air suspension unit composed of a damper section is known, and an air suspension unit can generally have good elastic properties even under a relatively large live load. In particular, it is often applied to cargo-loading vehicles such as trucks and bread trucks.

Furthermore, as described in, for example, Japanese Utility Model Application Publication No. 59-85708, such air suspension units are often equipped with an air spring section having a vehicle height adjustment function. . In an air suspension unit in which the air spring section has a vehicle height adjustment function, by supplying or removing air to a variable volume pressure chamber provided in the air spring section,
Control is performed to change the height of the vehicle body relative to the axle (hereinafter referred to as vehicle height) depending on the running state of the vehicle, the loading state, etc.

By the way, the damper part that constitutes the suspension unit such as the air suspension unit together with the spring part, for example, in a freight vehicle, normally has its damping force in a state where a predetermined live load is imposed (hereinafter referred to as a freight vehicle). It is assumed that the value is set to a relatively high value to deal with the situation (referred to as the state). Therefore, when the vehicle is loaded,
The ride comfort during operation is considered to be appropriate, but if the vehicle is in a state where no live load is imposed (hereinafter referred to as an empty vehicle state), there is a risk that the ride comfort may be significantly impaired. .

Therefore, the damper section is equipped with a variable damping force mechanism, which determines the loaded state of the vehicle and sets the damping force of the damper section to a relatively large value when the vehicle is loaded. In this case, it is conceivable to set the damping force of the damper portion to a relatively small value. In such a case, in order to determine whether the vehicle is in a loaded state or an empty state, for example, the height of the vehicle that is different between the loaded state and the empty state is detected, and if the vehicle height is relatively low, it is determined that the vehicle is in the loaded state. If the vehicle height is relatively high, it can be determined that the vehicle is in an empty state.

(Problems to be Solved by the Invention) However, as described above, in the air suspension unit in which the air spring part has a vehicle height adjustment function, the damper part has a damping force variable mechanism,
If it is intended that the damping force of the damper section be controlled according to the determination result of the loading state of the vehicle equipped with it,
The vehicle height of such a vehicle does not change depending on the loaded state, but is controlled by adjusting the vehicle height so that, for example, the change between the loaded state and the empty state is small. ,
When a loaded state and an empty vehicle state are determined based on the detected vehicle height, there is a problem in that it is difficult to accurately distinguish between a loaded state and an empty vehicle state.

In view of this, the present invention includes a suspension unit including an air spring section with a vehicle height adjustment function and a damper section with variable damping force, and adjusts the damper according to the loading condition of the vehicle equipped with the suspension unit. With a relatively simple configuration, it is possible to accurately determine the loaded state of the vehicle, for example, whether it is loaded or empty, even when the vehicle height is adjusted. As a result, it is an object of the present invention to provide a suspension device for an automobile that can appropriately control the damping force of a damper portion.

(Means for Solving the Problems) In order to achieve the above-mentioned object, an automobile suspension device according to the present invention has a pressure chamber whose volume changes, and is arranged between the automobile body and the wheel support portion. For a suspension unit consisting of an air spring section that expands and contracts according to changes in the volume of a pressure chamber, and a damper section that is arranged to damp vibrations of the air spring section and whose damping force is variable, A pressure detection means for detecting the pressure in a pressure chamber of the air spring section, a loading state determining means for determining the loading state of the automobile based on a detection output obtained from the pressure detecting means, and a determination output obtained from the loading state determining means. and a damping force control means for controlling the damping force of the damper portion based on the damping force.

(Function) In the automobile suspension device according to the present invention configured as described above, the pressure in the pressure chamber of the air spring portion, which corresponds to the loading condition of the automobile, is detected by the pressure detection means, and The state determining means determines the loaded state based on the pressure detected by the pressure detecting means, for example, distinguishes between a loaded state and an empty state. Then, based on the result of determining the loading state by the loading state determining means, the damping force control means is activated, and the damping force of the damper section is adjusted depending on the loading state at that time, for example, when the vehicle is empty compared to when the vehicle is loaded. In order to obtain a small damping force,
controlled.

In this case, the pressure in the pressure chamber of the air spring section varies depending on the load of the vehicle even when the vehicle height is adjusted. The determination of the loading state accurately follows the actual loading state. Therefore, even when the vehicle height is adjusted, the loaded state, for example, the loaded state and the empty state, can be accurately determined, and as a result, the damping force of the damper section can be appropriately controlled. You will be killed.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 equivalently shows the configuration of an example of an automobile suspension device according to the present invention, with the suspension device installed on the rear wheel side of the automobile.

This example includes suspension units 2L and 2R, each of which includes an air spring section and a damper section, and is associated with a left wheel and a right wheel of an automobile. These suspension units 2L and 2R have similar configurations, except for the way they are attached to the automobile. For example, as shown in FIG. 2, suspension unit 2R is shown. It is composed of

The suspension unit 2R shown in FIG. 2 includes an air spring section 32 in which a pressure chamber 30 whose volume can be changed is formed, and a damper section 34 connected to damp the vibration. It is formed. Air spring part 3
A piston rod 36 extends into the pressure chamber 30 of No. 2,
This piston rod 36 has an upper end that is connected to the air spring portion 3.
It protrudes through the upper end of the damper 2, and its lower end is slidably inserted into the damper part 34. A hollow portion 36a is formed in the piston rod 36, and this hollow portion 36a communicates with the pressure chamber 30 through a through hole provided in the piston rod 36 in its radial direction.

Piston rod 3 protruding from the upper end of air spring section 32
6 is attached to the inner race of the bearing 44, and the outer race of the bearing 44 is attached to the inner race of the bearing 44.
It is attached to a mount member 48 arranged to elastically support the air spring portion 32 with respect to the vehicle body 46. An upper bracket 50 is disposed at the upper end of the air spring section 32, and a coil surrounding the air spring section 32 is disposed between the upper bracket 50 and a lower bracket 52 attached to the outer peripheral surface of the damper section 34. A spring 54 is attached.

The damper section 34 has a damping force variable mechanism built therein so that its damping force can be changed. and,
A rolling diaphragm 38 whose one end is fixed to an inner wall forming the pressure chamber 30 of the air spring section 32 is fixed to the upper end of the damper section 34 . Further, the lower end portion of the damper portion 34 is fixed to a wheel mounting portion 42 of a wheel (right rear wheel) 40.

In the hollow part 36a of the piston rod 36 inserted into the damper part 34 through the pressure chamber 30 of the air spring part 32,
A control rod 56 is rotatably inserted through the damper section 34 to control an on-off valve (not shown) that is arranged within the damper section 34 and forms a variable damping force mechanism of the damper section 34 . An electric actuator 2SR is attached to the upper end surface of the piston rod 36 for rotating the control rod 56 to change the damping force of the damper section 34 by controlling the above-mentioned on-off valve.

A nozzle 60 that communicates with the hollow portion 36a of the piston rod 36 is disposed below the electric actuator 26H, and this nozzle 60 receives compressed air generated by a compressor 4 (FIG. 1), which will be described later. An air pipe is connected to supply the air into the pressure chamber 30 of the air spring section 32 through the hollow section 36a of the piston rod 36.

In this way, the suspension unit 2R is constructed, and as mentioned above, the suspension unit 2R is constructed.
L also has the same configuration as the suspension unit 2R.

As shown in FIG. 1, the compressed air is driven by the motor 3 and supplied through the air vibrator to the pressure chambers of the air springs in each of the suspension units 2L and 2R configured as described above. A compressor 4 is arranged. The output port of this compressor 4 is connected to one port of a directional control valve 6, and is connected to one port of a directional control valve IQ, 12 via an air dryer 8.
and 14, respectively.

The directional control valve 6 is a normally closed electromagnetic valve that switches the valve arrangement and opens when the solenoid attached to it is energized, and discharges compressed air introduced from one port into the atmosphere from the other port. It is an operating valve. Further, each of the directional control valves 10, 12 and 14 switches the valve arrangement and is brought into an open state when a solenoid attached thereto is energized. This is a closed electromagnetic operated valve. The other port of the directional control valve 10 is communicated with the pressure chamber of the air spring portion of the suspension unit 2R, and the directional control valve 12
The other port of the directional control valve 14 is communicated with a pressure chamber of the air spring portion of the suspension unit 2L, and the other port of the directional control valve 14 is communicated with a port of an air tank 16 that stores compressed air generated by the compressor 4. It is being The switching of the valve arrangement in each of these directional control valves 6, 10, 12 and 14 is performed by the control unit 2.
0 to each solenoid.

The air tank 16 is provided with a pressure sensor 16s, which generates a detection signal Sa when the air pressure in the air tank 16 is below a predetermined value, and supplies it to the control unit 20.

Also, the height of the vehicle body relative to the axle on the rear wheel side, that is,
A vehicle height sensor 22 is arranged to detect the vehicle height, and the vehicle height sensor 22 outputs a vehicle height signal s that takes a level corresponding to the vehicle height.
h is obtained and supplied to the control unit 20.

Further, a pressure switch 24 is connected to an air pipe that communicates the other port of the directional control valve 10 with the pressure chamber of the air spring portion of the suspension unit 2R. This pressure switch 24 is connected via a nozzle 60 provided in the suspension unit 1-2R and a hollow portion 36a of the piston rod 36, as shown in FIG.
The pressure chamber of the air spring section in the suspension unit 2R is communicated with the pressure chamber 30 formed in the air spring section 32 constituting the suspension unit 2R. Detects the air pressure inside the pressure chamber of the spring part. and,
For example, a pressure signal Sp that takes a high level when the detected air pressure is equal to or higher than a set value and takes a low level when the detected air pressure is less than the set value is obtained from the pressure switch 24 and is transmitted to the control unit 20. supplied to

When the control unit 20 is supplied with the detection signal Sa from the pressure sensor 16s, it sends a drive control signal Ss to the motor 3 to operate the motor 3, thereby putting the compressor 4 into an operating state.

At the same time, a valve control '+n signal is supplied to the solenoid of the directional control valve 14 to open the directional control valve 14. Thereby, compressed air generated by the compressor 4 is supplied to the air tank 16. And air tank 16
When the air pressure inside exceeds a predetermined value, the sending of the detection signal Sa from the pressure sensor 16s is stopped, and the supply of compressed air to the air tank 16 is stopped. As a result, compressed air is always stored in the air tank 16 with an air pressure exceeding a predetermined value.

The control unit 20 also controls the direction control valves 6 and 1 according to the level of the vehicle height signal sh supplied from the vehicle height sensor 22.
A valve control signal is supplied to the selected solenoid of 0.12 and 14 to open it, and compressed air from the air tank 16 enters the pressure chamber of the air spring portion of each of the suspension units 2L and 2R. As supplied or suspension units 2L and 2
Compressed air is discharged from the pressure chamber of the air spring portion in each R through the direction control valve 6, and thereby the vehicle height is adjusted to keep the vehicle height constant.

Further, the control unit 20 determines the loading state of the vehicle, for example, the loaded state and the empty state, based on the level of the pressure signal Sp supplied from the pressure switch 24, and depending on the result of the determination, the high level and the empty state are determined. A control signal Sc that takes a low level is formed and is transmitted to an electric actuator 2 disposed in a suspension unit 2R as shown in FIG.
6R and similarly supplied to an electric actuator 26L arranged in the suspension unit 2L. The electric actuators 26R and 26L that received the control signal Sc are
The damping force of the damper portion in each of the suspension units 2R and 2L is controlled according to the level of the control signal Sc.

At this time, when the control signal Sc supplied from the control unit 20 takes a high level, the electric actuator 26R increases the damping force of the damper section 34 forming the suspension unit 2R, as shown in FIG. On the other hand, when the control signal Sc takes a low level, the control rod 56 is rotated to reduce the damping force of the damper section 34 that constitutes the suspension unit 2R. control. At the same time, the electric actuator 26L also
Similarly to the electric actuator 26R, when the control signal Sc supplied from the control unit 20 takes a high level, the damping force of the damper part that constitutes the suspension unit l-2L becomes large, and on the other hand, the control signal Sc When is at a low level, control is performed to reduce the damping force of the damper section forming the suspension unit 2L.

For example, when a vehicle equipped with the suspension device configured as described above is placed in a loaded state, the vehicle height is first lowered by the loaded load, and the vehicle height sensor 22 indicates that the vehicle height is lowered. A vehicle height signal sh having a level indicating that the vehicle height has been lowered is supplied to the control unit 20. - The control unit 20 thereby controls the directional control valve 10.12
and 14, respectively, to open each directional control valve by supplying a valve control signal to each solenoid. As a result, the air tank,
Compressed air stored in the suspension unit 16 with an air pressure exceeding a predetermined value is supplied into the pressure chambers of the air spring portions of each of the suspension units 2L and 2R, and the damper portions connected to each air spring portion are made to protrude. The vehicle height is raised and returned to a predetermined value.

In this way, when the vehicle height is maintained constant by the vehicle height adjustment operation under a loaded state, the air pressure in the pressure chamber of the air spring portion of the suspension unit 2R detected by the pressure switch 24 is The pressure signal Sp reaches a predetermined value or more, and the pressure signal Sp having a high level is supplied from the pressure switch 24 to the control unit 20. The control unit 20 determines the loading state of the vehicle based on the pressure signal Sp that takes a high level, and supplies a control signal Sc that takes a high level to the electric actuators 26L and 26R.

As a result, the electric actuators 26L and 26R
As described above, control is performed to increase the damping force of each of the damper sections constituting the suspension units 2L and 2R. As a result, a comfortable ride can be obtained depending on the loaded state of the vehicle.

On the other hand, when a vehicle equipped with a suspension device configured as described above is left in an empty state, the carrying load is first removed and the vehicle height is raised;
A vehicle height signal sh having a level indicating that the vehicle height has been raised is supplied from the vehicle height sensor 22 to the control unit 20. Thereby, the control unit 20 controls the directional control valve 6
．． A valve control signal is supplied to each solenoid 10 and 12 to open each directional control valve. As a result, the compressed air in the pressure chambers of the air spring sections in each of the suspension units 2L and 2R is discharged into the atmosphere through the directional control valve 6, and the damper section connected to each air spring section is retracted to lower the vehicle height. It is lowered and returned to a predetermined value.

In this manner, when the vehicle height is maintained constant by the vehicle height adjustment operation in an empty vehicle state, the air pressure in the pressure chamber of the air spring portion of the suspension unit 2R detected by the pressure switch 24 is at a predetermined level. Therefore, the pressure signal Sp is supplied from the pressure switch 24 to the control unit 20 at a low level. The control unit 20 determines whether the car is empty based on the pressure signal Sp that takes a low level, and supplies a control signal Sc that takes a low level to the electric actuators 26L and 26R.

As a result, the electric actuators 26L and 26R
As described above, control is performed to reduce the damping force of each of the damper sections forming the suspension units 2L and 2R. As a result, a comfortable ride can be obtained depending on the empty vehicle condition.

As described above, by detecting the air pressure in the pressure chamber of the air spring portion of the suspension unit 2R while the vehicle height is maintained constant by the vehicle height adjustment operation, the loading It is possible to accurately determine the condition and empty state of the vehicle, and therefore the suspension and
The damping force of the damper portion in each of the units 2L and 2R can be set to an appropriate value depending on the loaded state and the empty front vehicle.

In the above example, the pressure switch 24 detects the air pressure in the pressure chamber of the air spring section of the suspension unit 2R engaged with the right rear wheel, but unlike this, the pressure The switch 24 may be configured to detect the air pressure in the pressure chamber of the air spring portion of the suspension unit 2L engaged with the left rear wheel,
Furthermore, the average value of the air pressure in the pressure chamber of the air spring portion in each of the suspension units 2L and 2R may be detected.

In addition, when a car is driven with a constant vehicle height, malfunctions caused by changes in air pressure in the pressure chamber of the air spring section of the suspension unit 2R caused by road bumps, etc., are a problem. In such a case, a delay circuit may be provided in the control unit 20, or a throttle may be formed between the pressure chamber of the air spring portion of the suspension unit 2R and the pressure switch 24 to slow down the responsiveness of the pressure switch 24. This can be avoided by taking the following measures.

(Effects of the Invention) As is clear from the above description, according to the automobile suspension device according to the present invention, the suspension unit includes an air spring portion having a vehicle height adjustment function and a damper portion having a variable damping force. t-(I! Eh, in order to change the damping force of the damper section according to the loading condition of the vehicle equipped with it, we can use a relatively simple structure to change the loading condition of the vehicle after the vehicle height has been adjusted, such as the loading condition of the vehicle. It is possible to accurately determine whether the vehicle is in a vehicle state or an empty vehicle state, and as a result, the damping force of the damper section can be appropriately controlled, and a comfortable ride can be obtained according to each state. .

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram showing an example of an automobile suspension device according to the present invention, and FIG. 2 is a schematic configuration diagram showing a specific example of a suspension unit used in the example shown in FIG. In the figure, 2L and 2R are suspension units, 6,
10. 12 and 14 are directional control valves, 20 is a control unit, 22 is a vehicle height sensor, 24 is a pressure switch, 30 is a pressure chamber, 32 is an air spring part, 34 is a damper part, 26L and 2
6R is an electric actuator. Figure 1

Claims (1)

[Claims] An air spring section that has a pressure chamber whose volume changes and is disposed between the vehicle body and the wheel support section and expands and contracts according to the change in the volume of the pressure chamber, and damps vibrations of the air spring section. a damper section whose damping force is variable; and a pressure detection means for detecting the pressure in a pressure chamber of the air spring section; A suspension device for an automobile, comprising a loading state determining means for determining a state, and a damping force control means for controlling a damping force of the damper portion based on a determination output obtained from the loading state determining means.