JPH0577621A - Controller for car height control - Google Patents

Abstract

PURPOSE:To provide improved fluid pressure source durability, electric power saving and reduction in noise at the time of stopping, and restrain a difference in car height with the car height in a reference car height range maintained when the difference in car height is generated in right and left wheels or front and left wheels during stopping, in a controller for car height control which carries out car height control with fluid pressure such as air pressure and oil pressure. CONSTITUTION:Fluid pressure chambers (b), (b) with a difference in car height is made to communicate with each other for generation of even inner pressure without driving fluid pressure source (a) when both the car heights of right and left wheels or front and rear wheels are within a reference car height range even if the difference in car height is generated in the right and left wheels or front and rear wheels during stopping.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle height adjustment control device for performing vehicle height adjustment control using fluid pressure such as air pressure or hydraulic pressure.

[0002]

2. Description of the Related Art Conventionally, as a vehicle height adjusting control device using air pressure, for example, one disclosed in Japanese Utility Model Laid-Open No. 58-95307 is known.

According to this conventional source, an electronically controlled air suspension composed of an air chamber containing compressed air and a shock absorber is used as a vehicle height adjusting means for each wheel, and a vehicle height provided near each air chamber. A device for adjusting the vehicle height by controlling whether to supply pressurized air from an air pressure source having an engine-driven compressor to the air chamber or to remove pressurized air from the air chamber from a regulating valve is shown. ..

[0004]

In the conventional vehicle height adjustment control device as described above, when the vehicle is stopped with the engine being driven and the vehicle height difference between the left and right wheels is equal to or greater than the specified value. Drives the air pressure source with a compressor to supply pressurized air from the air chamber on the lower wheel side of the left and right wheels to raise the vehicle height, and apply air from the air chamber on the higher wheel side of the left and right wheels. The vehicle height is controlled by eliminating the compressed air to reduce the vehicle height and keep the vehicle height difference between the left and right wheels within a specified value.

However, the vehicle height difference between the left and right wheels frequently becomes large while the vehicle is stopped with the engine driven,
Each time, the compressor is rotated and the discharge valve is opened, so it is necessary to increase the durability of these components, which increases the cost of the system. In addition, by rotating the compressor, battery consumption is accelerated due to power consumption, and noise is generated due to rotation of the compressor when the vehicle is stopped.

The present invention has been made in view of the above problems, and in a vehicle height adjustment control device for performing vehicle height adjustment control using a fluid pressure such as air pressure or hydraulic pressure, the left and right wheels are stopped. Alternatively, if there is a difference in vehicle height between the front and rear wheels, it is possible to improve the durability of the fluid pressure source, save power, and reduce noise when the vehicle is stopped, while suppressing the difference in vehicle height while maintaining the vehicle height in the standard vehicle height range. The task is to achieve.

[0007]

In order to solve the above problems, in the vehicle height adjustment control device of the present invention, even if there is a vehicle height difference between the left and right wheels or the front and rear wheels when the vehicle is stopped, the vehicle height of the left and right wheels or the front and rear wheels is increased. When both are within the standard vehicle height region, the fluid pressure chambers are communicated with each other to connect the fluid chambers having different vehicle heights without driving the fluid pressure source so as to equalize the internal pressure.

That is, as shown in the claim correspondence diagram of FIG. 1, vehicle height adjusting means c having a fluid chamber b communicating with a fluid pressure source a and provided between the wheel and the vehicle body, and vehicle height adjustment control Vehicle height detection means d for detecting the vehicle height at the wheel position, and vehicle height adjustment control means f for inputting at least the vehicle height detection value and performing vehicle height adjustment control by opening / closing control of the suspension valve e. In the vehicle height adjustment control device,
The vehicle height adjustment control means f is stopped, the vehicle height difference between the left and right wheels or the front and rear wheels is a predetermined value or more, and the vehicle heights of the left and right wheels or the front and rear wheels are both within the reference vehicle height range. In this case, the vehicle is characterized by having a constant-pressure control part g for stopping the vehicle that outputs a valve opening command that communicates the fluid chambers b of the left and right wheels or the front and rear wheels having different vehicle heights without driving the fluid pressure source a. ..

[0009]

[Effect] When the vehicle is stopped, the vehicle height difference between the left and right wheels or the front and rear wheels is more than a predetermined value, and the vehicle heights of the left and right wheels or the front and rear wheels are both within the reference vehicle height range, the vehicle is stopped at a constant pressure In the control unit g, a valve opening command that communicates the fluid chambers b of the left and right wheels or the front and rear wheels having a vehicle height difference is output without driving the fluid pressure source a.

For example, in the case where the vehicle height of one of the left and right wheels is low and the vehicle height of the other wheel is high, and there is a vehicle height difference of a magnitude for adjusting the vehicle height of the left and right wheels, Under the condition that both the left and right wheels are within the reference vehicle height region, the two fluid chambers b are communicated with each other, and the low internal pressure of the fluid chamber c on the low vehicle height side is
It is increased by the high internal pressure of the fluid chamber c on the high vehicle height side, and the internal pressures of the fluid chambers c and c are made equal pressure. By this equal pressure control, the vehicle height on the low vehicle height wheel side increases, and the vehicle height on the high vehicle height side decreases,
The difference in vehicle height between the left and right wheels is suppressed to a small level, and both the left and right wheels are kept at the vehicle height within the reference vehicle height range without driving the fluid pressure source a.

Here, the condition that both the left and right wheels or the front and rear wheels are within the reference vehicle height region is added as a condition for the equal pressure control. Firstly, the vehicle height adjustment control is performed in the reference vehicle height region. There is no dead zone area. Secondly, if equal pressure control is performed when both the left and right wheels or the front and rear wheels are out of the reference vehicle height area, the vehicle height difference can be suppressed to a small value, but both are out of the reference vehicle height area. It is because the vehicle height is kept high.

[0012]

EXAMPLES First, the structure will be described.

FIG. 2 is an overall view showing an FR vehicle to which the vehicle height adjustment control device of the embodiment of the present invention is applied, and FIG. 3 is a control system diagram showing the vehicle height adjustment control device of the embodiment.

As shown in FIG. 2, an FR vehicle to which the vehicle height adjustment control device of the embodiment in which only the front wheels are independently controlled is applied has an engine 2 and an exhaust system 4, and a left front wheel 5 and a right front wheel 6 are provided. , Left rear wheel 7 and right rear wheel 8 have air chambers 9a, 10a, 11a filled with compressed air, respectively, in the suspension parts.
12a (corresponding to a fluid chamber) and shock absorbers 9b, 1
A front left wheel strut 9, a front right wheel strut 10, a rear left wheel shock absorber 11, and a rear right wheel shock absorber 12 (each of which corresponds to a vehicle height adjusting means), which are composed of 0b, 11b, and 12b. It is provided.
Then, a detection signal from an input sensor 13 including a vehicle height sensor that detects the vehicle height at the left and right front wheel positions and the vehicle height at the rear wheel position is input, and the vehicle heights of the left and right front wheels and the vehicle heights of the rear wheels are independently determined. Air suspension control unit 1 controlled by
4 (corresponding to vehicle height adjustment control means) is provided.

The air chambers 9a, 10a, 11a, 12a
As shown in FIG. 3, the air control circuit that changes the amount and pressure of the compressed air to change the vehicle height is used as an air pressure source 34 (corresponding to a fluid pressure source) for increasing the vehicle height. Compressor 15 for supplying compressed air, and compressor 1
It has a motor 35 for driving the motor 5, a dryer 16 for removing the water content of the compressed air in the air circuit, and a discharge valve 17 that opens when the vehicle height is lowered. The dryer 16, left front wheel air circuit 18, right front wheel air circuit 19, rear wheel air circuit 2
0 are connected to each other via air pipes 21, 22, and 23. The left front wheel air circuit 18 has a left front wheel suspension valve 24 and a left front wheel sub-tank 25 that are opened and closed when adjusting the vehicle height.
It has a right front wheel suspension valve 26 and a right front wheel sub-tank 27 that open and close when adjusting the vehicle height, and the rear wheel air circuit 2
0 has a left rear wheel suspension valve 28, a left rear wheel sub-tank 29, a right rear wheel suspension valve 30, and a right rear wheel sub-tank 31, which are opened and closed when the vehicle height is adjusted.

As shown in FIG. 3, the air suspension control unit 14 includes, as input sensors, a left front wheel vehicle height sensor 13a (corresponding to vehicle height detecting means) and a right front wheel vehicle provided at the position of the front suspension member. A high sensor 13b (corresponding to vehicle height detecting means), a rear wheel vehicle height sensor 13c provided at the position of the rear stabilizer 32, an engine speed sensor 13d for detecting an engine speed, and a vehicle speed sensor 13e for detecting a vehicle speed. Other sensors and switches 13f such as a steering angle sensor, a mode setting switch and a brake switch are connected.

From the air suspension control unit 14, the valves 17, 24, 26 and 2 are connected.
By outputting a valve drive command to 8 and 30, normal vehicle height adjustment control that matches the vehicle height set by selection with a mode switch, etc. is performed, and the vehicle height difference between the left and right front wheels 5 and 6 is made while the vehicle is stopped. If, the vehicle height of each is in the standard vehicle height region DB, the left and right equal pressure control for opening the suspension valves 24, 26 is performed.

Next, the operation will be described.

FIG. 4 is a flow chart showing the flow of the processing for controlling the left and right equal pressures when the vehicle is stopped (corresponding to the equal pressure control section when the vehicle is stopped), and each step will be described below.

In step 40, it is judged whether or not the vehicle is stopped due to vehicle speed, brake operation, etc., and if YES, the routine proceeds to step 41. In step 41, the vehicle height difference Δhf between the left and right front wheels 5, 6 is controlled. High difference threshold ΔHfo
It is determined whether the above state continues for a predetermined time tfo or more, and in step 42, it is determined whether the left front wheel vehicle height FrLH and the right front wheel vehicle height FrRH are both within the reference vehicle height region DB.

When all the conditions of Step 40 to Step 42 are satisfied, the routine proceeds to Step 43. At Step 43, a command to open the suspension valves 24 and 26 is output, and the air chambers 9 of the left and right front wheel struts 9 and 10 are output.
The control to make the internal pressures of a and 10a equal is started.

In step 44, it is judged whether the vehicle height difference Δhf between the left and right front wheels 5, 6 is equal to or less than the control end vehicle height difference threshold ΔHfs for a predetermined time tfs or more, and the control end condition of step 44 is set. A command to open the suspension valves 24 and 26 continues to be output until it is satisfied. When the condition of step 44 is satisfied, the process proceeds to step 45, and in step 45, a command to close both the suspension valves 24 and 26 is output.

On the other hand, if NO in step 42, the process proceeds to step 46, in which the compressor 15 of the air pressure source 34 is rotated to supply pressurized air to the air chamber 9a or 10a on the low vehicle height side. The normal vehicle height adjustment control is started by removing the pressurized air from the high vehicle height side air chamber 10a or 9a.

In step 47, it is determined whether the vehicle height difference Δhf between the left and right front wheels 5, 6 is equal to or less than the control end vehicle height difference threshold ΔHfs for a predetermined time tfs or more, and the control end condition in step 47 is set. Step 46 until satisfied
Control is continued and the condition of step 47 is satisfied,
In step 48, a command to stop the compressor 15 or close the discharge valve 17 is output in step 48.

Therefore, for example, when one of the left and right front wheels 5, 6 stops on a flat road immediately after riding on a curb, etc., the control start vehicle height difference threshold ΔHfo is set for the left and right front wheels 5, 6.
If the above vehicle height difference occurs, step 42 that both the left front wheel vehicle height FrLH and the right front wheel vehicle height FrRH are within the reference vehicle height region DB
Under these conditions, the suspension valves 24 and 26 will be opened.

Here, as shown by the solid line in FIG. 5, of the left and right front wheels 5, 6, the right front wheel 6 has a high vehicle height and the left front wheel 5 has a low vehicle height.
By opening 4, 26, the low internal pressure of the air chamber 9a on the left front wheel 5 side, which is a low vehicle height, is increased by the high internal pressure of the air chamber 10a on the right front wheel 6 side, which is a high vehicle height, so that both air chambers 9a , 10
The internal pressure of a is made equal.

By this equal pressure control, the vehicle height on the left front wheel 5 side, which is a low vehicle height, is increased, and the vehicle height on the right front wheel 6 side, which is a high vehicle height, is decreased, as shown by the broken line in FIG. The difference in vehicle height between the left and right front wheels 5, 6 can be suppressed to a small level. Moreover, by including the condition that both the left front wheel vehicle height FrLH and the right front wheel vehicle height FrRH are within the reference vehicle height region DB in the start condition of the equal pressure control, after the equal pressure control,
The left and right front wheels 5 and 6 are both kept within the standard vehicle height region DB.

As described above, the vehicle height adjustment control device of the embodiment has the following effects.

(1) In a vehicle height adjustment control device for performing vehicle height adjustment control using air pressure, even if a vehicle height difference occurs between the left and right front wheels 5, 6 while the vehicle is stopped, the vehicle height Fr of the left and right front wheels 5, 6 is
When both LH and FrRH are within the standard vehicle height region DB, the vehicle stops because the two air chambers 9a and 10a having different vehicle heights are connected to each other without turning the compressor 15 of the air pressure source 34 to make the internal pressures equal. When there is a difference in vehicle height between the left and right front wheels 5 and 6, the durability of the compressor 15 and the exhaust valve 17 of the air pressure source 34 is improved, and power consumption and noise at vehicle stop due to the compressor 15 being stopped are reduced. While reducing the vehicle height, it is possible to suppress the vehicle height difference while keeping the vehicle height in the standard vehicle height region DB together.

Here, the reason why the durability of the compressor 15 and the discharge valve 17 can be improved is that equal pressure control can be achieved only by opening and closing the suspension valves 24 and 26. Regarding the durability of the suspension valves 24 and 26, the required durability does not change because the valves 24 and 26 must be opened and closed even when the normal vehicle height adjustment control is performed.

Since the engine noise and road noise are low when the vehicle is stopped, the sound generated by the rotation of the compressor 15 becomes a problem for passengers. On the other hand, since the rotation frequency of the compressor 15 is reduced, the noise at the vehicle stop can be reduced.

(2) A constant time tfo is set as the starting condition of the equal pressure control.
Therefore, it is prevented that the equal pressure control is erroneously started when the vehicle height difference Δhf becomes equal to or higher than the control start vehicle height difference threshold ΔHfo due to the getting on and off of personnel or luggage.

(3) A predetermined time tfs is set as the end condition of the equal pressure control.
Therefore, when the vehicle height difference Δhf momentarily becomes equal to or less than the control end vehicle height difference threshold ΔHfs during the equal pressure control due to the entry and exit of personnel or luggage, the equal pressure control is erroneously ended. It is prevented from doing.

Although the embodiment has been described above, the specific configuration and control contents are not limited to the embodiment, and the present invention is applicable even if there are changes and additions within the scope of the present invention. include.

For example, in the embodiment, an example of the vehicle height adjustment control device for controlling only the front wheels independently left and right has been shown. However, as shown in FIG. )
It may be a device for performing vehicle height adjustment control. 6 differs from the embodiment shown in FIG. 3 in that the rear wheel air circuit 20 is a left rear wheel air circuit 20a and a right rear wheel air circuit 20b.
The left rear wheel vehicle height sensor 13g (corresponding to the vehicle height detecting means) and the right rear wheel vehicle height sensor 13h (corresponding to the vehicle height detecting means) are provided for the left and right rear wheels 7 and 8, respectively. It is provided. The vehicle height control for the left and right rear wheels is performed in the same manner as for the left and right front wheels. Further, in the case of the four-wheel independent control, the front-rear equal pressure control may be performed for the left front wheel and the right front wheel.

The present invention can also be applied to a vehicle height adjustment control device using hydraulic pressure.

[0037]

As described above, according to the present invention, in the vehicle height adjustment control device for performing vehicle height adjustment control using fluid pressure such as air pressure or hydraulic pressure, the left and right wheels or the front and rear wheels are stopped while the vehicle is stopped. Even if there is a difference in vehicle height, if the vehicle heights of the left and right wheels or the front and rear wheels are both within the standard vehicle height range, the fluid pressure chambers are connected without changing the fluid pressure source to equalize the internal pressure. If there is a difference in vehicle height between the left and right wheels or the front and rear wheels while the vehicle is stopped, the vehicle height in the standard vehicle height range can be improved while improving the durability of the fluid pressure source, saving power and reducing noise when the vehicle is stopped. It is possible to obtain the effect that the vehicle height difference can be suppressed while maintaining the above.

[Brief description of drawings]

FIG. 1 is a claim correspondence diagram showing a vehicle height adjustment control device of the present invention.

FIG. 2 is an overall view showing an FR vehicle to which a vehicle height adjustment control device of an embodiment is applied.

FIG. 3 is a control system diagram showing a vehicle height adjustment control device of the embodiment.

FIG. 4 is a flow chart showing a flow of a left and right equal pressure control process operation at a vehicle stop performed by an air suspension control unit of the vehicle height adjustment control device according to the embodiment.

[Fig. 5] When there is a difference in vehicle height between the left and right front wheels while the vehicle is stopped,
It is an operation explanatory view showing a vehicle height change situation before and after left-right equal pressure control.

FIG. 6 is a control system diagram showing a vehicle height adjustment control device by four-wheel independent control.

[Explanation of symbols]

 a fluid pressure source b fluid chamber c vehicle height adjusting means d vehicle height detecting means e suspension valve f vehicle height adjusting control means g constant pressure control section at vehicle stop

Claims (1)

[Claims] 1. A vehicle height adjusting means having a fluid chamber communicating with a fluid pressure source and provided between a wheel and a vehicle body, and a vehicle height detecting means for detecting a vehicle height at a wheel position to be subjected to vehicle height adjustment control. And a vehicle height adjustment control means for inputting at least the vehicle height detection value and performing vehicle height adjustment control by opening / closing control of a suspension valve, wherein the vehicle height adjustment control means includes a vehicle stop adjustment means. When the vehicle height difference between the left and right wheels or the front and rear wheels is a predetermined value or more and the vehicle heights of the left and right wheels or the front and rear wheels are both within the standard vehicle height range, the vehicle is driven without driving the fluid pressure source. A vehicle height adjustment control device having a constant-pressure control unit during vehicle stop that outputs a valve opening command that communicates fluid chambers of left and right wheels or front and rear wheels having height differences.