JPS6341212Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to an electronically controlled suspension that can reduce the spring constant of a fluid spring to substantially zero and improve riding comfort.

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, supplying fluid to the fluid springs to raise the vehicle height will increase the internal pressure of the fluid springs, making the suspension stiffer. The drawback was that the ride was uncomfortable.

This idea was made in view of the above points,
The purpose is to make the spring constant of the fluid spring essentially zero (that is, to keep the internal pressure of the fluid spring constant),
To provide an electronically controlled suspension that softens the suspension and improves riding comfort.

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 above-mentioned shock absorber 17 is the absorber switching actuator 1.
4, hardware/software switching is performed.
Further, the amount of compressed air in the air spring chamber 16 of the air spring 13 is adjusted via an air passage (not shown) formed in the piston rod 15. Furthermore, the cylinder 17 of this device 11
The lower part of 1 is attached to a 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.

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 vehicle height judgment adjustment circuit 32 that controls vehicle height adjustment. In this vehicle height judgment adjustment circuit 32, a vehicle height signal corresponding to the operation signal of the vehicle height selection switch 31 is set, and this vehicle height signal is compared with the vehicle height signal output from the vehicle height sensor 20. Ru. Then, a signal representing the difference between both signals is calculated.
Then, from this signal and the reference internal pressure value of the air spring chamber 16, the internal pressure value of the air spring chamber 16 is calculated when the vehicle height is set to the vehicle height selected by the vehicle height selection switch 31.

By the way, 34 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 35.
It is compressed in the dryer 36, dried in the dryer 36, and stored in the reserve tank 34. Here, 34a is a pressure switch, and 37 is an engine. A pressure reducing valve 38 is provided between the reserve tank 34 and the air passage leading to the air spring chamber 16.
A solenoid valve 39 for sealing off the compressed air in the air spring chamber 16 is also interposed. Also,
A solenoid valve 40 is interposed between the reserve tank 34 and the absorber switching actuator 14. By the way, 41 is an air motor.
Due to the rotation of this air motor 41, the pressure reducing valve 38
A setting spring (not shown) within is compressed.
The output side of this pressure reducing valve 38 is adjusted to a pressure proportional to the compression force of this setting spring. In other words, the pressure reducing valve 38 is connected to the reserve tank 34.
The pressure of compressed air supplied from the air motor 41
This valve reduces pressure by controlling the rotation of the valve, and maintains the pressure constant after pressure reduction. A switching valve 42 is provided between the air motor 41 and the reserve tank 34.
The switching of the switching valve 42 is performed by a control signal output from the solenoid valve drive circuit 33. Here, 43 to 45 are mufflers, respectively.

Further, 46 is a hardware/software selection switch that allows the suspension state to be selected in three stages (``AUTO'', ``SOFT'', and ``HARD''). "SOFT"
When the terminal and the "HARD" terminal are selected, an H level signal is output.

Further, 47 is a speed sensor that detects the vehicle speed, and the output of this speed sensor 47 is input to a threshold value determination circuit 48 that outputs an H level signal when the vehicle speed exceeds a certain speed. Reference numeral 49 is a handle angle sensor that detects the rotation angle of a handle (not shown), and the output of this handle angle sensor 49 is a threshold value discrimination circuit that outputs an H level signal when the rotation angle of the handle exceeds a certain angle. 50 is input. Furthermore, 51 is an acceleration sensor as a vehicle body attitude sensor that detects changes in the attitude of the vehicle body. This acceleration sensor 51 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. And the acceleration is
When applied to the front and back, right and left, or up and down, the weight tilts or moves, thereby detecting the acceleration state of the vehicle body. . This acceleration sensor 51
The output is input to a threshold value determination circuit 52 which outputs an H level signal when the acceleration state of the vehicle body (front/rear, up/down, left/right) exceeds a certain value. Furthermore, 53 is an accelerator opening sensor that detects the accelerator opening, and the output of this accelerator opening sensor 53 is input to a threshold value determination circuit 54 that outputs an H level signal when the accelerator opening exceeds a certain value. Ru. Furthermore, 55 is a brake pressure sensor that detects the degree of depression of the brake, and the output of this brake pressure 55 is inputted to a threshold value determination circuit 56 which outputs an H level signal when the degree of depression of the brake exceeds a certain value. The threshold value determination circuits 48, 50, 52,
The outputs of 54 and 56 are each input to one input terminal of an AND circuit 58 via an OR circuit 57. The output of the "SOFT" terminal of the hardware/software selection switch 46 is input to the other input terminal of the AND circuit 58 via an inverter 59. Furthermore, the output of the AND circuit 58 and the "HARD" of the hardware/software selection switch 46 are
The outputs of the terminals are connected to the solenoid drive circuit 61 and the vehicle height judgment adjustment circuit 3 via OR circuits 60, respectively.
2 is input. The solenoid drive circuit 61 controls the driving of the solenoid valves 39 and 40.

Next, the operation of this invention configured as described above will be explained. First, the case of adjusting the vehicle height will be explained. For example, if you want to raise the vehicle height, set the vehicle height selection switch 31 to the "HIGH" position. The operation signal of this vehicle height selection switch 31 is output to a vehicle height judgment adjustment circuit 32, and is converted into a vehicle height signal corresponding to this operation signal. This vehicle height signal is then compared with the vehicle height signal output from the vehicle height sensor 20. Then, a signal representing the difference between both signals is calculated. Then, from this signal and the reference internal pressure value of the air spring chamber 16, the internal pressure value of the air spring chamber 16 is calculated when the vehicle height is set to the vehicle height selected by the vehicle height selection switch 31. Based on this internal pressure value, it is determined whether or not to increase the internal pressure of the air spring chamber 16. In that case, since the vehicle height is to be increased, the operation of increasing the internal pressure of the air spring chamber 16 is performed as described below. That is, a control signal is output from the vehicle height judgment adjustment circuit 32 to the solenoid valve drive circuit 33. Based on this control signal, the solenoid valve drive circuit 33 switches the switching valve 42 to change the direction of compressed air supplied to the air motor 41, thereby controlling the rotation direction and rotation speed of the air motor 41. The rotation of the air motor 41 compresses a setting spring (not shown) in the pressure reducing valve 38, and a pressure proportional to this compression force is applied to the air spring chamber 1.
6 is output. In other words, the pressure reducing valve 38 is a valve that reduces the pressure of the compressed air supplied from the reserve tank 34 by controlling the rotation of the air motor 41, and maintains the pressure constant after the pressure is reduced. Therefore, the vehicle height increases due to the compressed air having a pressure higher than the reference internal pressure, which is reduced in pressure by the pressure reducing valve 38 and supplied to the air spring chamber 16. Furthermore, since the pressure reducing valve 38 performs control to keep the internal pressure of the air spring chamber 16 constant, the spring constant of the air spring chamber 16 can be made substantially zero even when the vehicle height is adjusted, and the suspension can be maintained at a constant level. It's soft and provides a comfortable ride.

When lowering the vehicle height, the vehicle height selection switch 31 is set to the "LOW" position. It will be held in
That is, by controlling the pressure reducing valve 38, the air spring chamber 1
The internal pressure of No. 6 is set low. Below, air spring chamber 1
After the internal pressure of the air spring chamber 16 is set low, the internal pressure of the air spring chamber 16 is kept constant by controlling the pressure reducing valve 38.
Therefore, even if the vehicle height is adjusted, the spring constant of the air spring chamber 16 can be made substantially zero, resulting in a soft suspension and good riding comfort.

Next, if you want to set the suspension to hard, set the hardware/software selection switch 46 to "HARD".
position. As a result, the H level signal is transmitted to the vehicle height judgment adjustment circuit 3 via the OR circuit 60.
2 and the solenoid drive circuit 61. As a result, the vehicle height adjustment by the vehicle height adjustment circuit 32 is stopped. Then, the solenoid drive circuit 61 is driven to close the solenoid valve 39 and open the solenoid valve 40. By closing the solenoid valve 39, supply and exhaust to and from the air spring chamber 16 are stopped. Therefore, even if the internal pressure of the air spring chamber 16 increases due to some vertical movement of the vehicle body, the operation of keeping the internal pressure constant and making the suspension soft as described above is eliminated.
The suspension is said to be hard. Also,
Compressed air is sent to the actuator 14 by opening the solenoid valve 40 . As a result, the shock absorber 17 is switched to hard.

Note that when the compressed air is discharged from the reserve tank 34, the internal pressure decreases, but when the internal pressure falls below the set pressure, the compressor 35 is activated by a signal from the pressure switch 34a. Then, the compressor 35 stops when the internal pressure in the reserve tank 34 becomes equal to or higher than the set pressure.

On the other hand, if the suspension is to be soft, the hardware/software selection switch 46 is set to the "SOFT" position. As a result, "SOFT"
The H level signal output from the terminal is sent to inverter 5.
9 and input to the AND circuit 58, the gate of the AND circuit 58 is closed. Therefore, even if the speed sensor 47, the steering wheel angle sensor 49, etc. output an H level signal from the threshold value determination circuits 48, 50, etc., the output of the AND circuit 58 remains at the L level. For this reason, the suspension is not hardened as described above when the hardware/software selection switch 46 is set to the second "HARD" position.

In addition, if the hardware/software selection switch 46 is set to the "AUTO" position, the speed sensor 47 and the steering wheel angle sensor 49
When an H level signal is output from the threshold value determination circuits 48, 50, etc., the H level signal is outputted to the vehicle height determination adjustment circuit 32 and the solenoid drive circuit 61 via the OR circuit 60. This makes the suspension hard. Next, another embodiment of this invention will be explained using FIG. 2. Names in FIG. 2 that are the same as those in FIG. 1 are given the same numbers. In another embodiment of this invention shown in FIG. 2, the pressure reducing valve 38 is controlled by a servo motor 142 and a motor drive circuit 133, and the other configuration and operation are the same as that of the embodiment shown in FIG. is the same as , so it will be omitted.

As detailed above, according to this invention, the internal pressure of the fluid spring is kept constant, so even after adjusting the vehicle height, the spring constant of the fluid spring can be made essentially zero, improving riding comfort. It is possible to provide an electronically controlled suspension that can be improved.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an electronically controlled suspension according to one embodiment of this invention, and FIG. 2 is a diagram showing an electronically controlled suspension according to another embodiment of this invention. 11...Suspension device, 13...Air spring, 16...Air spring chamber, 32...Vehicle height judgment adjustment circuit, 33...Solenoid valve drive circuit, 41
...Air motor, 42...Switching valve.

Claims (1)

[Scope of utility model registration request] a suspension having a fluid spring, a pressure reducing valve interposed between the fluid spring and a fluid pressure supply source and adjusting the output side to a pressure proportional to the compression force of the set spring; An electronically controlled suspension comprising a pressure reducing valve driving means for controlling the compression force of a setting spring.