JPH0231286Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to an electronically controlled suspension device that can prevent pinching of a vehicle body due to unevenness of the road surface.

An electronically controlled suspension device is being considered that improves ride comfort and handling stability by electronically controlling the damping force of a shock absorber and the spring constant of an air spring. In such an electronically controlled suspension system, it is desired to keep the vehicle body level by preventing pitching of the vehicle body due to unevenness of the road surface.

This idea was made in view of the above points,
The purpose is to provide an electronically controlled suspension device that prevents pitching of the vehicle body due to unevenness of the road surface, keeps the vehicle body level, and improves ride comfort and handling stability.

Hereinafter, an electronically controlled suspension device according to an embodiment of the invention will be described with reference to the drawings. In Figure 1, S _FR indicates a suspension unit for the front right wheel of an automobile, S _FL indicates a suspension unit for the left front wheel, S _RR indicates a suspension unit for the right rear wheel, and S _RL indicates a suspension unit for the left rear wheel. ing. The suspension units S _FR , S _FL , S _RR , and S _RL have main air spring chambers 11a to 11d and sub air spring chambers 12a to 12, respectively.
d, shock absorbers 13a to 13d, and a coil spring (not shown) used as an auxiliary spring. Further, 15a to 15d are switching devices for switching the damping force of the shock absorbers 13a to 13d to hard or soft. The switching devices 15a to 15d are controlled by the controller 16. In addition, 17a
-17d are bellows, respectively.

Furthermore, a compressor 18 compresses the atmospheric air sent from an air cleaner (not shown) and supplies it to the dryer 19. This dryer 19 dries the supplied compressed air using silica gel or the like. The compressed air from the dryer 19 is stored in a front wheel reserve tank 20F and a rear wheel reserve tank 20R via a pipe A, respectively.
Reference numeral 21 denotes a pressure sensor provided in the reserve tank 20F. When the internal pressure of the reserve tank 20F decreases to a set value or less, a signal from the pressure sensor 21 causes the compressor 18 to operate.
When the internal pressure of the reserve tank 20F exceeds the set pressure, the compressor 18 is stopped by a signal from the pressure sensor 21.

Further, the reserve tank 20F and the main air spring chamber 11a are connected to the reserve tank 20F and the main air spring chamber 11b via the air supply solenoid valve 22a.
are connected via the air supply solenoid valve 22b. Furthermore, the reserve tank 20R and the main air spring chamber 11c are connected to an air supply solenoid valve 22c.
The reserve tank 20R and the main air spring chamber 11d are connected via an air supply solenoid valve 22d. The above solenoid valves 22a to 22
d is a valve that is always closed.

Further, the compressed air in the main air spring chamber 11a passes through the exhaust solenoid valve 23a, the compressed air in the main air spring chamber 11b passes through the exhaust solenoid valve 23b, and the compressed air in the main air spring chamber 11c passes through the exhaust solenoid valve 23a. The compressed air in the main air spring chamber 11d is released to the atmosphere via the exhaust solenoid valve 23c and an exhaust pipe (not shown). The solenoid valves 23a to 23d are valves that are always closed.

Furthermore, the main air spring chamber 11a and the auxiliary air spring chamber 12a each have a spring constant switching solenoid valve 26.
The main air spring chamber 11b and the auxiliary air spring chamber 12b are connected to a spring constant switching solenoid valve 2 via a.
6b, the main air spring chamber 11c and the auxiliary air spring chamber 12c are connected to the spring constant switching solenoid valve 26c, and the main air spring chamber 11d and the auxiliary air spring chamber 12d are connected to the spring constant switching solenoid valve 26d. are connected to each other via

Furthermore, the main air spring chambers 11a and 11b are connected to the communication pipe B.
The main air spring chambers 11c and 11d are connected via the communication pipe c and the communication solenoid valve 27R. The communication solenoid valves 27F and 27R are valves that are always open.

By the way, the solenoid valves 22a to 22
d, 23a-23d, 26a-26d, 27F,
Opening/closing control of 27R is performed by signals from the controller 16.

Furthermore, 30 is a steering sensor that detects the steering angle of the steering wheel, 31 is a brake sensor that detects on/off of the brake, 32 is an accelerator opening sensor that detects the opening of the accelerator, and 33 is a steering sensor that detects the steering angle of the steering wheel, 33 is an accelerator opening sensor that detects the opening of the accelerator, and 33 is a steering sensor that detects the steering angle of the steering wheel. An acceleration sensor that detects acceleration, 34 a vehicle speed sensor that detects vehicle speed, 35 a front vehicle height sensor that detects the height of the front part (front wheel part) of the car, and 36 a rear part (rear wheel part) of the car.
This is a rear vehicle height sensor that detects the vehicle height of the vehicle. Signals from the sensors 30 to 36 are supplied to the controller 16.

Next, the operation of this invention constructed as described above will be explained with reference to the flowchart of FIG. When the ignition key is turned on, the process shown in the flowchart of FIG. 2 starts. First, in step S1, the vehicle height signal output from the vehicle height sensor 35 is input to the controller 16, and the time t required for the vehicle height signal to change from "001" to "100" is calculated in step S2. In other words, this time t is the time required for the change curve A of the vehicle height sensor 35 to change from one reversal to another as shown in FIG. Furthermore, in step S2, the time t is
If it is determined "NO" in this step S2 where it is determined whether the time is 400 ms or more, the process proceeds to the above step S1.
Return to On the other hand, if the determination in step S2 is ``YES'', the process proceeds to step S3, where it is determined whether the pitch l of the change curve A of the vehicle height sensor 35 shown in FIG. 3 is 10 m or more. This step S
If the determination in step 3 is "NO", the process returns to step S1. On the other hand, if the determination in step S3 is ``YES'', the process advances to step S4 and preparations for pitching control are made. In step S4, the vehicle speed V at time a when the direction of change of the change curve A of the vehicle height sensor 35 is reversed is read from the vehicle speed sensor 34 into the controller 16. Then, the time for opening the air supply solenoid valves 22a, 22b or the exhaust solenoid valves 23a, 23b for the front wheels starting from the above time point a.
t ₁ is calculated as shown below. Furthermore, starting from the above point a, the rear wheel air supply solenoid valve 2
2c, 22d or exhaust solenoid valve 2
The time t ₂ for opening 3c and 23d is calculated as shown below.

Here, t ₁ =t-x=l/2V-x...(1) _t2 =t-x+L/V=l+2L/2V-x...(2) In addition, in the above equations (1) and (2), L is the wheel base, and x is the time required for attitude control (≒350ms).

Thereafter, pitching control is performed after step S5. First, in step S5, the vehicle height signal output from the vehicle height sensor 35 is read into the controller 16 again. Then, it is determined whether the vehicle height signal is "000", "101", or something else.
Here, when the vehicle height signal is "000", it indicates that the suspension is extended, and the vehicle height signal is "000".
As the number increases to 001, 010, etc., it indicates that the suspension is shrinking. If it is determined in step S5 that the vehicle height signal is "000", the process advances to step S6. In other words, from time a to arrow T
change in direction. In this step S6, the front wheel exhaust solenoid valves 23a and 23b are opened ₁ second after time a, and the main air spring chambers 11a and 1 are opened.
A portion of the compressed air in 1b is exhausted. and,
In step S7, simultaneously with the processing in step S6, the rear wheel air supply solenoid valve 22c is
and 22d are opened after t ₁ second as shown in FIG. 3B, and compressed air is fed into the main air spring chambers 11c and 11d. This lowers the height of the front wheels,
The rear wheels are raised to keep the vehicle level.

On the other hand, if it is determined in step S5 that the vehicle height signal is "101", the process proceeds to step S8. In other words, when the most compressed state of the front wheels is detected, the process proceeds to step S8. In this step S8, the front wheel air supply solenoid valves 22a and 22b are opened _t2 seconds after time a, and compressed air is sent into the main air spring chambers 11a and 11b.
Furthermore, the process advances to step S9 and the process proceeds to step S8.
Solenoid valve 2 for rear wheel exhaust at the same time as processing
3c and 23d are opened t ₂ seconds after time b to discharge the compressed air in the main air spring chambers 11c and 11d. This raises the vehicle height of the front wheels and lowers the vehicle height of the rear wheels, keeping the vehicle level. After the above steps S7 and S9 are completed, the process returns to the above step S4, and when the output signal of the vehicle height sensor 35 becomes "000" or "101", the process returns to the above steps S6 and S7 or steps S8 and S9.
By repeating this process, it is possible to prevent pitching of the vehicle body when the vehicle is traveling on a road surface that is continuously uneven.

As detailed above, according to this invention, it is possible to provide an electronically controlled suspension device that prevents pitching of the vehicle body due to unevenness of the road surface, keeps the vehicle body level, and improves riding comfort and handling stability. can.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an electronically controlled suspension device according to an embodiment of the invention, FIG. 2 is a flowchart showing the operation, and FIG. 3 is a diagram showing a change curve of a vehicle height sensor. 11a-11d...main air spring chamber, 22a-2
2d... Air supply solenoid valve, 23a to 23
d...Exhaust solenoid valve, 20F, 20R
... Reserve tank, 34 ... Vehicle speed sensor, 35
...Front vehicle height sensor.

Claims (1)

[Scope of utility model registration request] A vehicle speed sensor that detects vehicle speed, a vehicle height sensor that detects vehicle height, a suspension unit installed for each wheel that uses a combination of main and sub air spring chambers and auxiliary springs, and a reserve tank that stores compressed air. , an air supply control valve provided for each suspension unit interposed in the air supply piping connecting this reserve tank and the main air spring chamber of the suspension unit, and a main air supply control valve for each suspension unit. The exhaust control valve provided for each suspension unit installed in the exhaust pipe connecting the air spring chamber and the exhaust pipe, and the time from reversal to reversal of the change curve of the output signal of the vehicle height sensor mentioned above. and attitude control means that detects a period of change in the output signal of the vehicle height sensor and controls the opening and closing of the air supply control valve and the exhaust control valve to keep the vehicle height constant when a period of time exceeds a certain time. An electronically controlled suspension device featuring: