JPH0417364Y2 - - Google Patents

Description

[Detailed explanation of the invention] [Technical field of the invention] This invention is a G
The present invention relates to an electronically controlled suspension device that performs posture control according to the output voltage of a sensor.

[Technical background of the invention and its problems] The vehicle is equipped with a spring member, such as an air spring chamber, interposed between the wheels and the vehicle body, and a spring force adjustment device that can adjust the spring force of this spring member. In conventional suspensions, displacement of the wheels was detected by analog detection means such as potentiometers to adjust the vehicle height and control the attitude. However, installing such a potentiometer under the spring of the suspension unit poses a problem in terms of durability, and it is being considered to use a differential transformer type G sensor to perform attitude control. .

[Purpose of the invention] The present invention was made in view of the above points, and its purpose is to develop an electronic control system that uses a differential transformer type G sensor to effectively prevent changes in the posture of the vehicle body during braking. The purpose of the present invention is to provide a suspension device.

[Summary of the invention] A fluid spring chamber interposed between the wheels and the vehicle body,
In a suspension equipped with a fluid supply and discharge device that controls the supply and discharge of fluid in the fluid spring chamber, there is a G sensor that outputs a voltage corresponding to the longitudinal acceleration of the vehicle body, and a voltage that is determined from the output of this G sensor. Formula V+α・V' where V is the output voltage of the G sensor, α is a constant other than zero that indicates weighting, and V' is the value that cancels the change in vehicle body posture when the time differential value of the output voltage V exceeds a predetermined value. In this electronically controlled suspension device, the fluid supply/discharge device is driven so that a biasing force in the direction of the fluid spring chamber is generated in the fluid spring chamber, thereby preventing a change in the attitude of the vehicle body.

[Embodiment of the invention] An electronically controlled suspension device according to an embodiment of the invention will be described below with reference to the drawings.
In Figure 1, the air suspension unit
Since FS1, FS2, RS1, and RS2 each have almost the same structure, the air suspension unit will be explained below using the symbol S, unless the front and rear units are specifically explained. do.

That is, the air suspension unit S incorporates a strut-type shock absorber 1, and this shock absorber 1 is fitted into a cylinder attached to the front wheel or rear wheel side, and is slidably inserted into the cylinder. The cylinder is equipped with a piston, and the cylinder moves up and down relative to the piston rod 2 in response to the up and down movement of the wheels, thereby making it possible to effectively absorb shock.

Incidentally, an air spring chamber 3 which also serves as a vehicle height adjustment fluid chamber is disposed coaxially with the piston rod 2 in the upper part of the shock absorber 1, and a bellows 4 is formed in a part of this air spring chamber. Therefore, the passage 2a provided in the piston rod 2
By supplying and discharging air to and from the air spring chamber 3 through the piston rod, the piston rod can be moved up and down.

Further, the outer wall of the shock absorber 1 is provided with a spring receiver 5a facing upward, and the outer wall of the air spring chamber 3 is provided with a spring receiver 5b facing downward.
are formed, and a coil spring 6 is loaded between these spring receivers 5a and 5b.

Thus, 11 is a compressor. This compressor 11 compresses the atmospheric air sent from the air cleaner 12 and supplies it to the dryer 13 . The compressed air dried with silica gel or the like from the dryer 13 is transferred to the reserve tank 15 via the check valve 14 . It is stored in the high pressure side reserve tank 15a. This reserve tank 1
5 is provided with a low pressure side reserve tank 15b. A compressor 16 driven by a compressor relay 17 is provided between the reserve tanks 15a and 15b. Further, a pressure switch 18 is provided which is turned on when the pressure in the low pressure side reserve tank 15b becomes equal to or higher than atmospheric pressure.
When the pressure switch 18 is turned on, the compressor relay 17 is driven. As a result, the reserve tank 15b is always kept below atmospheric pressure. The route by which compressed air is supplied from the high-pressure side reserve tank 15a to the suspension unit S is indicated by a solid arrow. That is, the compressed air from the reserve tank 15a is passed through the air supply solenoid valve 19, the air supply flow rate control valve 20 consisting of a three-way valve, the check valve 21, the front right solenoid valve 22, and the front left solenoid valve 23. It is sent to the front right suspension unit FS2 and the front left suspension unit FS1. Similarly, the compressed air from the reserve tank 15a is supplied to an air supply solenoid valve 19, an air supply flow rate control valve 20 consisting of a three-way valve, and a check valve 2.
4. It is sent to the rear right suspension unit RS2 and the rear left suspension unit RS1 via the rear right solenoid valve 25 and the rear left solenoid valve 26. On the other hand, the exhaust route from the suspension unit S is indicated by a broken line arrow. In other words, the suspension unit
Exhaust from FS1 and FS2 is solenoid valve 2
2, 23, the exhaust flow rate control valve 27, the exhaust direction switching valve 28, and the residual pressure valve 29 are sent to the low pressure side reserve tank 15b. Furthermore, the exhaust from the suspension units FS1 and FS2 is controlled by solenoid valves 22 and 23, an exhaust flow rate control valve 27, an exhaust direction switching valve 28, and a dryer 1.
3. Exhaust solenoid valve 30, air cleaner 1
2 to the atmosphere. In addition, the exhaust from the suspension units RS1 and RS2 includes solenoid valves 25 and 26, an exhaust flow control valve 27,
It is sent to the low pressure side reserve tank 15b via the exhaust direction switching valve 28 and the residual pressure valve 29. Note that when the pressure in the reserve tank 15b is lower than the pressure in the air spring chamber 3, the residual pressure valve 29 is opened, and when the pressure in the reserve tank 15b is higher than the pressure in the air spring chamber 3, the residual pressure valve 29 is closed. . Furthermore, suspension unit RS1,
Exhaust from RS2 uses solenoid valves 25 and 26,
Exhaust flow rate control valve 27, exhaust direction switching valve 28, dryer 13, exhaust solenoid valve 3
0, released to the atmosphere via the air cleaner 12.

Further, 31 is a vehicle height sensor, and this vehicle height sensor 3
Reference numeral 1 denotes a front vehicle height sensor 31F that is attached to the lower arm 32 of the front right suspension of the automobile to detect the front vehicle height of the automobile, and a front vehicle height sensor 31F that is attached to the lateral rod 33 of the rear left suspension of the automobile to detect the rear vehicle height of the automobile. The rear vehicle height sensor 31R detects the height of the vehicle, and detection signals are supplied from these vehicle height sensors 31F and 31R to a control unit 34 serving as a vehicle height adjustment control section.

Each sensor 31F, 31 in the vehicle height sensor 31
R is adapted to detect the distance from the normal vehicle height level, the low vehicle height level, or the high vehicle height level, respectively.

Furthermore, the speedometer has a built-in vehicle speed sensor 35, which detects the vehicle speed and transmits the detection signal to the control unit 3.
4.

Further, a differential transformer type G sensor 36 is provided as a vehicle body posture sensor for detecting changes in the posture of the vehicle body. The configuration of this differential transformer type G sensor will be described later using FIG. 2.

Further, numeral 37 is an indicator for displaying oil pressure, and the display of this indicator 37 is controlled by the control unit 34. A steering sensor 38 detects the rotational speed of the steering wheel 39, that is, the steering speed, and its detection signal is sent to the control unit 34. Furthermore, 4
0 is an accelerator opening sensor (not shown) that detects the depression angle of an accelerator pedal of the engine, and its detection signal is sent to the control unit 34. Further, 41 is a compressor relay for driving the compressor 11, and this compressor relay 41 is controlled by a control signal from the control unit 34. Furthermore, 42 is a pressure switch that is turned on when the pressure in the reserve tank 15a falls below a predetermined value, and its output signal is output to the control unit 34. That is, when the pressure in the reserve tank 15a falls below a predetermined level, the pressure switch 34 is turned on, and the compressor relay 41 is operated under the control of the control unit 34. As a result, compressor 1
1 is driven, compressed air is sent into the reserve tank 15a, and the pressure inside the reserve tank 15a is increased to a predetermined value or higher. The opening and closing of the solenoid valves 19, 22, 23, 25, 26, 30 and the valves 20, 27, 28 are controlled by control signals from the control unit 34.

Next, the differential transformer type G sensor 36 of FIG. 1 will be explained with reference to FIG. In FIG. 2, 51 is the sensor body. This sensor body 5
1 is filled with buffer oil 52.
Springs 53a and 53b are attached to the protrusion 51a within the sensor body 51, and a core 54 is supported by a support member 55 and suspended from the lower ends of the springs 53a and 53b.
Further, 56 is a printed circuit board whose upper end is attached to the convex portion 51a and whose lower end is attached to the coil assembly 57. A primary coil 57a and a secondary coil 57b are wound around the coil assembly 57.

Note that FIG. 3 is a diagram showing an electrical equivalent circuit of the differential transformer type G sensor 36 shown in FIG. 2.
That is, the printed circuit board 56 includes an oscillator 61,
A drive circuit 62 and an AC/DC converter 63 are mounted, and the core 54 is
When is displaced back and forth, the output voltage VG of converter 63 changes according to the amount of displacement. Here, the fourth
The figure shows an example of the output voltage VG of the G sensor 36. As shown in the figure, as the acceleration G increases, the voltage VG increases in proportion to it.

Next, the operation of an embodiment of the present invention configured as described above will be explained. This embodiment describes anti-nose dive control during braking. First, in step S11, V+ is calculated from the output corresponding to the longitudinal acceleration output from the G sensor 36.
The control unit 34 determines whether α·V' is greater than or equal to a predetermined value. In addition, V is the G sensor 36
output voltage, α is a non-zero constant indicating weighting,
V' is the time differential value of the output voltage V. If the determination in step S11 is ``YES'', the process advances to step S12, where the air supply solenoid valve 19, solenoid valve 25, and solenoid valve 26 are opened for a predetermined period of time. Therefore, the compressed air from the reserve tank 15a is transferred to the air supply solenoid valve 1.
9, air supply flow control valve 20, check valve 2
1 through the front suspension unit
The air is sent to the air spring chamber 3 of FS1 and FS2. This raises the front vehicle height. On the other hand, the compressed air discharged from the air spring chamber 3 of the rear suspension units RS1 and RS2 is supplied to the solenoid valve 25, the solenoid valve 26, the exhaust flow control valve 27, the exhaust direction switching valve 28, and the residual pressure valve 2.
9 and is discharged to the reserve tank 15b.
This lowers the rear vehicle height and keeps the vehicle level. After the valves are turned on for a predetermined period of time, the air supply solenoid valve 19, solenoid valve 25, and solenoid valve 26 are turned off. Then, the pressure on the brake becomes weaker and the above V
When +αV' becomes less than or equal to the predetermined value, the process proceeds to step S13, where a ``YES'' determination is made, and the process proceeds to step S14.
In this step S14, the air supply solenoid valve 19, solenoid valve 22, and solenoid valve 23 are turned on. Therefore, the compressed air in the air spring chambers 3 of the front suspension units FS1 and FS2 is transferred to the reserve tank 15b via the solenoid valve 22, solenoid valve 23, exhaust flow rate control valve 27, exhaust direction switching valve 28, and residual pressure valve 29. be discharged. On the other hand, the compressed air in the reserve tank 15a is supplied to the air supply solenoid valve 1.
9, air supply flow control valve 20, check valve 2
4, Solenoid valve 25, Solenoid valve 2
6 to the rear suspension unit RS1,
It is sent to the air spring chamber 3 of RS2. This results in
The posture of the vehicle body is returned to its original state. In this way, attitude control during braking is performed. In this way, when determining the start and end of attitude control, (V+α・
V′), attitude control can be performed with appropriate timing for both slow deceleration and rapid deceleration. This is because when there is a gradual decrease or acceleration, the determination of V is effective, and when there is a sudden decrease or acceleration, the determination of V' is effective.

[Effects of the invention] As detailed above, according to the invention, attitude control can be performed at an appropriate timing for both gradual deceleration and rapid deacceleration. It is possible to provide an electronically controlled suspension device that can effectively prevent shaking.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing an electronically controlled suspension device according to the present invention, Fig. 2 is a sectional view of a differential transformer type G sensor, and Fig. 3 is a diagram showing an electrical equivalent circuit of the differential transformer type G sensor. 4 is a diagram showing the output voltage of the differential transformer type G sensor, and FIG. 5 is a flowchart showing the operation of an embodiment of the present invention. 15a, 15b... Reserve tank, 19...
Air supply solenoid valve, 20... Air supply flow rate control valve, 22, 23, 25, 26... Solenoid valve, 27... Exhaust flow rate control valve, 28... Exhaust direction switching valve, 29... Residual pressure valve, 30... …
Exhaust solenoid valve, 34...control unit, 36...differential transformer type G sensor.

Claims (1)

[Scope of claim for utility model registration] A fluid spring chamber interposed between the wheel and the vehicle body,
In a suspension equipped with a fluid supply and discharge device that controls the supply and discharge of fluid in the fluid spring chamber, there is a G sensor that outputs a voltage corresponding to the longitudinal acceleration of the vehicle body, and a voltage that is determined from the output of this G sensor. Formula V+α・V' where V is the output voltage of the G sensor, α is a constant other than zero that indicates weighting, and V' is the value that cancels the change in vehicle body posture when the time differential value of the output voltage V exceeds a predetermined value. An electronically controlled suspension device comprising: a controller that drives the fluid supply/discharge device so that a biasing force in the direction of the fluid spring chamber is generated in the fluid spring chamber.