JPS6341211Y2 - - Google Patents

Description

[Detailed explanation of the invention] This invention makes the spring constant of the fluid spring substantially zero during normal running, and prevents the occurrence of rolls, dives, squats, etc. when the load is transferred. Regarding electronically controlled suspension that improves comfort and handling stability.

An automobile equipped with a suspension having a fluid spring can adjust the vehicle height by adjusting the internal pressure of the fluid spring.

However, when a large number of passengers are on board and the vehicle height is lowered, if fluid is supplied to the fluid springs to raise the vehicle height, the internal pressure of the fluid springs increases, making the suspension harder and making the ride less comfortable. The disadvantage was that it worsened. Furthermore, in automobiles equipped with such electronically controlled suspensions, it is desired to further improve riding comfort and steering stability by preventing rolls, dives, and squats caused by load movement.

This idea was made in view of the above points,
The purpose of this is to make the spring constant of the fluid spring virtually zero during normal driving, and to increase or decrease the internal pressure of the fluid spring when a load is transferred to prevent rolls, dives, squats, etc. The objective is to provide an electronically controlled suspension that improves ride comfort and handling stability.

Hereinafter, an electronically controlled suspension according to an embodiment of the invention will be described with reference to the drawings. In the figure, 11 is a suspension device. This suspension device 11 incorporates a strut-type damping force switching type shock absorber, and the suspension function is achieved by a coil spring 12, an air spring 13, and a shock absorber 17. The shock absorber 17 is switched between hardware and software by an absorber switching actuator (not shown). The air spring 13 is formed within the piston rod 14, and the amount of compressed air in the air spring chamber 16 is adjusted via an air passage 15. Furthermore, cylinder 1 of this device 11
The lower part of 71 is attached to the wheel 18,
The upper part of the device 11 is attached to the vehicle body via a mount rubber 19. Here, 20 is a vehicle height sensor attached to the vehicle body side, and 21 is a load sensor configured of, for example, a piezoelectric element and detects the load of each wheel.

By the way, 31 has three levels of vehicle height (``HIGH'',
This is a vehicle height selection switch that selects between ``MIDDLE'' and ``LOW.'' The operation signal of this vehicle height selection switch 31 is input to a target vehicle height setting circuit 32, and a vehicle height signal indicating a vehicle height corresponding to each stage is set. The vehicle height signal output from the target vehicle height setting circuit 32 and the vehicle height signal output from the vehicle height sensor 20 are each input to a vehicle height signal comparison circuit 33, where the vehicle height signals are compared. Then, based on the comparison signal from the vehicle height signal comparison circuit 33, the internal pressure correction signal generation circuit 34 outputs an internal pressure correction signal corresponding to the difference between the respective vehicle height signals to one input terminal of the adder 35. .

Reference numeral 36 denotes a reference internal pressure value storage unit that stores the reference internal pressure value of the air spring chamber 16 when the vehicle is empty.The reference internal pressure value stored in this reference internal pressure value storage unit 36 is sent to the internal pressure setting signal generation circuit 37. The signal is input and converted into a reference internal pressure signal corresponding to the reference internal pressure value. Then, this reference internal pressure signal is sent to the adder 35.
is input to the other input terminal of. In this adder 35, the internal pressure correction signal and the reference internal pressure signal are added to calculate a target internal pressure signal. Furthermore, the target internal pressure signal output from the adder 35 is input to one input terminal of the adder 38.

Further, the load on each wheel sensed by the load sensor 21 is extracted as a load signal by a load detector 39. The load signal output from the load detector 39 is sent to a memory 40 that stores the latest load Wo for each wheel, and a load increase calculation section 41 that calculates the increase in load. The value ΔP (=W-Wo/A) obtained by converting the load increase amount calculated by the load increase calculation section 41 into an internal pressure is inputted to the other input terminal of the adder 38 via the selector 42.

By the way, 43 is a reserve tank in which compressed air is stored. In other words, the air sent from the air cleaner (not shown) is sent to the compressor 4.
It is compressed in 4, dried in a dryer 45, and stored in this reserve tank 43. Here, 43a is a pressure switch, and 46 is an engine. Furthermore, an electropneumatic proportional valve 47 and a solenoid valve 48 for preventing leakage of compressed air when the power is turned off are interposed between the reserve tank 43 and the air passage 15 communicating with the air spring chamber 16. The output of the adder 38 is inputted to the electropneumatic proportional valve 47 as a control signal. This electro-pneumatic proportional valve 47 is a control valve that adjusts the opening degree of the valve and the direction in which compressed air flows in accordance with an input signal, and controls the pressure on the air spring chamber 16 side to a pressure that corresponds to the input signal. Here, 4
9 is a muffler.

Further, 50 is a power supply ON/OFF detection circuit that detects the on/off state of the power supply, that is, the ignition, and the output of this power supply ON/OFF detection circuit 50 is inputted to a solenoid valve drive circuit 51 that controls the opening and closing of the solenoid valve 48. Ru. Turn on the above power/
When the OFF detection circuit 50 detects that the power is turned off, the solenoid valve 48 closes.

By the way, 52 is a steering wheel angle sensor that detects the rotation angle of a steering wheel (not shown), and the output of this steering wheel angle sensor 52 is a threshold value discrimination circuit that outputs an H level signal when the rotation angle of the steering wheel exceeds a certain angle. 53. Furthermore, 54 is an acceleration sensor as a vehicle body attitude sensor that detects changes in the attitude of the vehicle body. This acceleration sensor 54 is designed to detect changes in pitch, roll, and yaw of the vehicle body posture on the automobile springs using a weight or the like. When acceleration acts in the front and back, left and right, or up and down directions, the weight tilts or moves, and the acceleration state of the vehicle body is detected. The output of this acceleration sensor 54 is input to a threshold value determination circuit 55 which outputs an H level signal when the acceleration state of the vehicle body (front and back, up and down, left and right) exceeds a certain value. Furthermore, 56 is an accelerator opening sensor that detects the accelerator opening, and the output of this accelerator opening sensor 56 is input to a threshold value determination circuit 57 that outputs an H level signal when the accelerator opening exceeds a certain value. Ru. Furthermore, 58 is a brake pressure sensor that detects the degree of depression of the brake, and the output of this brake pressure sensor 58 is inputted to a threshold value determination circuit 59 that outputs an H level signal when the degree of depression of the brake exceeds a certain value. . Also, 60
is a speed sensor that detects the vehicle speed, and the output of this speed sensor 60 is input to a threshold value determination circuit 61 that outputs an H level signal when the vehicle speed exceeds a certain speed. The threshold value determination circuits 53, 55, 5
The outputs of 7 and 59 are input to an OR circuit 62, respectively. The output of the OR circuit 62 is sent to the selector 42 and a vehicle height adjustment stop force control circuit 63 that stops the vehicle height adjustment or forcibly switches the vehicle height to a lower vehicle height. The selector 42 is closed when an H level signal is input from the OR circuit 62. Also,
The output signal of the threshold value determination circuit 61 is also input to the vehicle height adjustment/stop force control circuit 63 .

Next, the operation of this device configured as described above will be explained. First, when an ignition switch (not shown) is turned on, the process shown in the flowchart of FIG. 2 is started. First, the engine is started in step _S1 . At the same time, in step _S2 , the reference internal pressure value stored in the reference internal pressure value storage section 36 is sent to the internal pressure setting signal circuit 37 and converted into a reference internal pressure signal corresponding to the reference iron internal pressure value. . This reference internal pressure signal is sent to adders 35 and 3.
8 to the electropneumatic proportional valve 47 as a control signal. Next, proceed to step _S3 and proceed to the air spring chamber 16.
The solenoid valve 48, which had been contained, is opened. In response to this control signal input to the electropneumatic proportional valve 47, the supply and exhaust of compressed air is controlled by the voltage proportional valve 47 so that the reference internal pressure Pp is generated in the air spring chamber 16. Then, proceeding to step _S4 , the load W of each wheel detected by the load sensor 21 is
is detected and stored in the memory 40 as Wo. Next, proceeding to step _S5 , the vehicle height signal comparison circuit 3 determines whether the vehicle height detected by the vehicle height sensor 20 is equal to the target vehicle height output from the target vehicle height setting circuit 32.
Comparisons are made in 3. If the determination in step _S5 is ``YES'', the process proceeds to step <sub>S6</sub> , where the load W on each wheel is detected by the load sensor 21, and the process returns to step <sub>S5</sub> . Further, the load W detected in step <sub>S6</sub> is averaged 20 times and stored in the memory 4.
Stored as 0. On the other hand, if the determination in step <sub>S5</sub> is "NO", the process proceeds to step <sub>S7</sub> , where it is detected whether the conditions for adjusting the vehicle height are satisfied. For example, when the vehicle speed is 3 km/h or less, the vehicle height adjustment is performed immediately, and when the vehicle speed is 3 km/h or more, the vehicle height adjustment is performed when this state continues for 10 seconds. For example, when the vehicle height selection switch 31 is set to the "HIGH" position, which raises the vehicle height, the vehicle height signal comparison circuit 33 determines that the target vehicle height is greater than the output of the vehicle height sensor 20. and,
The vehicle height is adjusted in step <sub>S8</sub> . In this example, since the target vehicle height is larger, the internal pressure correction signal generation circuit 34 outputs a positive internal pressure correction signal. As a result, the positive internal pressure correction signal is added to the reference internal pressure signal supplied to the electropneumatic proportional valve 47. Therefore, the compressed air stored in the reserve tank 43 is sent into the air spring chamber 16 via the electropneumatic proportional valve 47 in an amount corresponding to the positive internal pressure correction signal. As a result, the vehicle height becomes higher. After this vehicle height adjustment, even if the internal pressure of the air spring chamber 16 changes, it is controlled by the electropneumatic proportional valve 47 to keep the internal pressure constant. Further, during vehicle height adjustment, the load W is continuously detected by the load sensor 21 and stored in the memory 40. This step
After the process in <sub>S8</sub> is completed, the process returns to the process in step <sub>S5</sub> . If the determination at step <sub>S5</sub> is ``YES'', the processes from step _S6 described above are performed. In addition, set the vehicle height selection switch 31 to "LOW"
When set to the position , a negative internal pressure correction signal output from the internal pressure correction signal generation circuit 34 is input to the electropneumatic proportional valve 47 . For this reason, air spring chamber 1
6 is discharged into the exhaust pipe 49 via the solenoid valve 48 and the electropneumatic proportional valve 47 in an amount corresponding to the negative internal pressure correction signal.
As a result, the vehicle height decreases. As above, the second
The vehicle height is adjusted by the operation of the flowchart shown in the figure.

Next, vehicle body attitude control will be explained using the flowchart shown in FIG. Threshold value determination circuits 53 and 5 are based on the handle angle sensor 52, acceleration sensor 54, accelerator opening sensor 56, and brake pressure sensor 58.
When an H level signal is output from 5, 57, and ₅₉ , a determination of ``YES'' is made in step S1, and the vehicle body posture control is performed in step _S2 and thereafter. Also,
An H level signal is output from the OR circuit 62 to the vehicle height adjustment stop force control circuit 63, and the vehicle height adjustment is stopped under the control of the vehicle height adjustment stop force control circuit 63. Further, the output of the OR circuit 62 is output to the selector 42.
Therefore, the output signal of the load increase calculation unit 41 is input to the other input terminal of the adder 38. Next, the process proceeds to step _S2 , and the load W detected by the load sensor 21 is outputted to the load increase calculating section 41 via the load detector 39. Then, the process proceeds to step _S3 , and the load increase calculating section 41 calculates "ΔP=W-Wo/A". This load increase calculation unit 41 calculates the change in the load applied to each wheel (W-
The amount of change ΔP in the internal pressure within the air spring chamber 16 is calculated by dividing Wo) by the pressure receiving area A. The amount of change ΔP in the internal pressure is added to the reference internal pressure signal in an adder 38. Then, the sum of the reference internal pressure signal and the internal pressure change amount ΔP is input to the electropneumatic proportional valve 47 as a control signal. For example, when the load W detected by the load sensor 21 increases, ΔP becomes positive, and the compressed air stored in the reserve tank 43 is sent to the air spring chamber 16 via the electropneumatic proportional valve 47. This raises the vehicle height.

In other words, the rear of the car lowers when the load is applied at the start, but by raising the vehicle height, the body maintains a horizontal posture and improves riding comfort. On the other hand, when the load W detected by the load sensor 21 decreases, ΔP becomes negative, and the compressed air in the air spring chamber 16 is discharged to the exhaust pipe 49 via the electropneumatic proportional valve 47. Therefore, the vehicle height is lowered. For example, when the rear of the car rises when the brakes are applied suddenly, the vehicle height is lowered to keep the car level and provide a comfortable ride. When the above processing is completed, the process returns to step _S1 , and when it is determined that vehicle body posture control is not necessary, the process returns to step _S5 of the flowchart of FIG.

Note that when the vehicle speed detected by the speed sensor 60 is equal to or higher than the speed set by the threshold value determination circuit 61, an H level signal is sent from the threshold value determination circuit 61 to the vehicle height adjustment stop force control circuit 63. Output. Therefore, a low vehicle height is forcibly selected under the control of the vehicle height adjustment/stop forced control circuit 63. Thereby, running stability during high-speed operation can be improved.

As detailed above, according to this invention, the spring constant of the fluid spring is made substantially zero during normal running, and the occurrence of rolls, dives, squats, etc. is prevented when the load is transferred. It is possible to provide an electronically controlled suspension that can improve ride comfort and handling stability.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an electronically controlled suspension according to an embodiment of this invention, and FIGS. 2 and 3 are flowcharts showing the operation, respectively. 11...Suspension device, 13...Air spring, 16...Air spring chamber, 31...Vehicle height selection switch, 33...Vehicle height signal comparison circuit, 34...Internal pressure correction signal generation circuit, 39...Load Detector, 47...
...Electro-pneumatic proportional valve.

Claims (1)

[Scope of utility model registration request] A suspension having a fluid spring, a control valve that controls supply and discharge of fluid to the fluid spring to maintain the internal pressure of the fluid spring at a set internal pressure according to a control signal, and a vehicle height detected by a vehicle height sensor. A first controller that outputs the control signal to the control valve in order to maintain the internal pressure of the fluid spring so that the vehicle height matches the target vehicle height when it is determined that vehicle height adjustment is necessary by comparing the vehicle height with the target vehicle height. When the control valve driving means, the load sensor that detects the load applied to the wheels, the driving state detection sensor that detects the driving state of the vehicle, and the driving state detection sensor detect that the vehicle body is in a state where an attitude change occurs. and second control valve driving means for outputting a control signal to increase or decrease the set internal pressure of the fluid spring in accordance with an increase or decrease in the load detected by the load sensor.