JPS60209312A - Automobile height controller - Google Patents

Abstract

PURPOSE:To exactly control the height of an automobile, without hunting, by using a relatively large time constant to integrate a vehicle height detection signal, until the start of the vehicle height control, and by using a relatively small time constant to integrate the signal, at the end of the control. CONSTITUTION:Oil passage changeover valves having solenoids 5a, 5b are shifted by a control unit 10 to regulate the height of an automobile. The control unit 10 comprises a first and a second integration circuits 30, 31 whose time constants are set at tau1 and tau2 (tau1<tau2) and which receive the output signal of a vehicle height sensor 12, and a vehicle height judgement circuit 34 connected to a relay switch 33 which is for choosing one of the integration circuits. Since no output is transmitted through feed lines 38a, 38b before the start of the control of the vehicle height, the relay switch 33 is connected to the second integration circuit 31 by the action of a relay drive circuit 40 based on the L-output of an OR gate 39. At the end of the vehicle height control, the relay switch 33 is connected to the integration circuit 30.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a vehicle height adjustment device for an automobile.

(1) (Prior art) Since the car body is elastically supported by the axle via a suspension system, the car body rises and falls according to the weight of the car, and when braking suddenly or descending from the platform, the front of the car sinks, causing the car to rise and fall. Sometimes the rear of the vehicle sinks. In addition, when driving on rough roads, the vehicle body must be raised high or it will be damaged, and when traveling at high speeds, the vehicle body must be lowered or it will lack running stability and be disadvantageous in terms of aerodynamic characteristics.

Therefore, conventionally, a vehicle height sensor was attached between the vehicle body and the axle.
Various vehicle height adjustment devices have been put into practical use that perform feedback control using the detection signal so that the vehicle height becomes a target vehicle height.

For example, the "vehicle suspension automatic leveling device" described in Japanese Utility Model Application Publication No. 47-22623 is
By controlling the vehicle height adjustment hydraulic system using the vehicle height signal obtained by processing the vehicle height sensor's detection signal with an integral circuit, the influence of vertical vibration caused by disturbances transmitted from the road surface to the axle is eliminated. It is designed to respond to changes in average vehicle height.

By the way, when controlling the vehicle height using the (2) vehicle height signal obtained by the integral processing as described above, the following problem occurs.

As shown in Figure 5, the high level vehicle height region (H
o±α) to the low-level vehicle height region (I70±α), start the vehicle height adjustment at point P and lower the vehicle height, and the integral vehicle height value (curve C2) becomes the integral Since it is accompanied by a time delay depending on the time constant of the circuit, point P1
By the time the integral vehicle height value reaches the upper limit of the low-level vehicle height region and the vehicle height adjustment is finished, the actual vehicle height (curve Co) has already fallen below the lower limit of the low-level vehicle height region. Point P
At time point 2, the vehicle height is adjusted again in the direction of raising the vehicle height so that the integral vehicle height value does not fall below the lower limit value. In other words, the hunting phenomenon described above occurs, making it impossible to accurately control the vehicle height.

Therefore, it is conceivable to set the time constant of the integrating circuit to a small value, but in that case, the effect of disturbance due to unevenness of the road surface will appear, making it impossible to achieve the intended purpose.

(Objective of the Invention) (3) The present invention has been made in view of the above-mentioned problems, and is free from the influence of actual vehicle height fluctuations due to disturbances such as road surface irregularities, and the time of the vehicle height value obtained by integral processing. An object of the present invention is to provide a vehicle height adjustment device for an automobile that does not cause a hunting phenomenon caused by delay.

(Structure of the Invention) The vehicle height adjustment device of the present invention includes a vehicle height adjustment means disposed between a wheel support member and a vehicle body, and a vehicle height sensor that detects a displacement in the relative height of the vehicle body with respect to the wheels. and a vehicle height control means that receives the output of the vehicle height sensor and controls the vehicle height adjustment means so that the vehicle height falls within the permissible range of the target vehicle height, and the vehicle height control means controls the vehicle height until the start of the vehicle height adjustment. Control is performed using the vehicle height value obtained by integrating the output signal of the vehicle height sensor with a predetermined time constant, and the output signal of the vehicle height sensor is controlled at a time constant smaller than the above time constant from the start to the end of vehicle height adjustment. Control is performed using one of the vehicle height value obtained through integral processing and the actual vehicle height value obtained without integral processing.

(Effects of the Invention) (4) As described above, the present invention uses the vehicle height value obtained by integrating the output signal of the vehicle height sensor with a predetermined relatively large time constant until the start of vehicle height adjustment. Since the vehicle height is controlled according to the average vehicle height fluctuation without being affected by disturbances such as unevenness of the road surface, the vehicle height adjustment is completed when the output signal of the vehicle height sensor is set at the above time. Since control is performed using the vehicle height value obtained through integration processing with a relatively small time constant for a constant or the actual vehicle height value, it is possible to prevent the hunting phenomenon caused by the time delay caused by the integration processing, and the responsiveness of vehicle height control is excellent. .

(Example) Embodiments of the present invention will be described below with reference to the drawings.

This vehicle height adjustment device is designed to prevent the vehicle from being affected by disturbances caused by uneven road surfaces, etc. when adjusting the vehicle height from one allowable target vehicle height range to another allowable target vehicle height range. Until the start of high adjustment, the vehicle height is controlled using the vehicle height signal ) From the beginning to the end, the vehicle height signal X1 is obtained by processing the output signal of the vehicle height sensor 12 by the first integrating circuit 30 with a relatively small time constant.
The vehicle height is controlled with good responsiveness using the

That is, this vehicle height adjustment device for an automobile includes a strut 2 corresponding to each wheel 1 of a suspension system, and each strut 2 described above.
a hydraulic drive device 4 connected to an oil chamber via an oil passage 3;
A control unit 10 switches and controls the electromagnetic oil passage switching valve 5 of the hydraulic drive bag W4, and four vehicle height sensors 12 are installed between the link arm 11 of the suspension system and the vehicle body 13 in the vicinity of each wheel 1. The output signal is sent to control unit 1.
a vehicle height sensor 12 that outputs to 0, and the control unit 10
and a target vehicle height setting switch 15 that outputs the target vehicle height to the target vehicle height.

The strut 2 is a hydraulic cylinder interposed between the housing 16 and the vehicle body 13 at the connection part between the axle 14 and the wheel 1.
It functions as a strut and shock absorber for the suspension system, and at the same time as a vehicle height adjustment means.

(6) As shown in FIGS. 2 and 3, the lower end of the cylinder body 17 of the strut 2 is fixed to the housing 16 via the sleeve-shaped coupling member 19, and the piston protrudes upward from the cylinder body 17. The upper end of the rod 18 is connected to the vehicle body 13 via a mount washer 20 and an annular loose IH rubber 21.

A piston valve 2 is provided at the lower end of the piston rod 18.
2 is provided, and an oil hole 23 opened at the lower end of the piston rod 18 and provided through the piston rod 18 is connected to the oil passage 3 at the upper end side of the piston rod 18, and is also connected to the oil chamber of the diaphragm type accumulator 28. Connected.

The piston valve 22 is the orifice 2 of the piston 24.
The upper oil is By restricting the oil flow from the chamber 27a to the lower oil chamber 27b, the strut 2
The strut 2 is buffered so that it does not expand suddenly, and the strut 2 is buffered so that it does not suddenly contract by restricting the oil flow from the lower oil chamber 27b to the upper oil chamber 27a with the contraction damper (7) ping valve. This allows it to function as a shock absorber.

The accumulator 28 is for absorbing high frequency pressure pulsations of the pressure oil due to high frequency vibrations propagating from the road surface to the wheels 1.

When pressure oil is supplied to the strut 2 from the oil passage 3, the amount of oil in the lower oil chamber 27b and upper oil chamber 27a increases, so the piston rod 1B extends upward and the vehicle height is adjusted higher. On the other hand, when the pressure oil is discharged from the strut 2 through the oil passage 3, the amount of oil decreases, so the piston rod 1
8 contracts downward and the vehicle height is adjusted lower. Furthermore, code 2
9 is a stopper for regulating the maximum vehicle height.

The hydraulic drive device 4 includes a hydraulic pump 6, a motor 7, a relief valve 8, and an oil passage switching valve 5.
is a 4-point, 3-position switching valve, and in the illustrated position, the pressure oil from the hydraulic pump 6 is relieved by the tank lid (8), and the front wheel oil passage 3a and the rear wheel oil passage 3b are shut off. When the oil supply solenoid 5a is energized and switched to the oil supply position, pressure oil flows into both oil passages 3a and 3b.
When the oil draining solenoid 5b is energized and switched to the oil draining position, the pressure oil from both oil passages 3a and 3b is drained to the oil tank 9.

The control unit IO includes a first integrating circuit 30 that corresponds to each vehicle height sensor 12 and receives an output signal from each vehicle height sensor 12.
and a second integrator circuit 31, and a first integrator circuit 3 of each of these pairs.
0 and each relay switch 3 corresponding to the integral circuit 31 in FIG.
3 through each pair of first integrating circuit 30 and second integrating circuit 31
a vehicle height determination circuit 34 which selectively receives an output from the target vehicle height setting switch 15 and receives an output signal from the target vehicle height setting switch 15; a valve drive circuit 35; and a valve drive circuit 3 from the vehicle height determination circuit 34.
5, an amplifier AND gate 37a interposed in the amplifier output path 36a that outputs a signal for operating the oil supply solenoid 5a of the oil path switching valve 5, and the vehicle height determination circuit 34.
to the valve drive circuit 35 (9) AND gate 1-37b for down, which is interposed in the output path 36b for down, which outputs a signal for operating the oil drain solenoid 5b of the oil path switching valve 5, and the above-mentioned valve. An amplifier power supply path 38a and a down power supply path 38b that output drive currents from the drive circuit 35 to the oil supply solenoid 5a and the oil drain solenoid 5b, respectively, and the above-mentioned up and down power feed paths 38a.
- A first OR gate 39 whose input terminal is connected to 38b, and a relay drive circuit 4 that receives the output of the first OR gate 39 and excites the coils 33a of the four relay switches 33.
0, an OFF delay circuit 41 that receives the output of the first OR gate 39, an inverter 42 that receives the output of the delay circuit 41 and inverts the output, and the first OR gate 39.
and a second OR gate 43 which receives the output of the inverter 42 and outputs it to one input terminal of each of the up and down AND gates 37a and 37b.

Each of the vehicle height sensors 12 is composed of, for example, a rotary potentiometer, and is interposed between the vehicle body (10) 13 near each wheel 1 and the link arm 11 of the suspension system.
The resistance value increases or decreases in accordance with the vertical movement of the link arm 11 corresponding to the vertical movement of the link arm 11, and the height of the vehicle body 13 relative to the wheels 1, that is, the vehicle height, is detected from the fluctuation of this resistance value. The detection signal
1, but various vehicle height sensors other than this may be used.

The target vehicle height setting switch 15 allows the driver to set the target vehicle height in stages (for example, 3 high, medium, and low) by setting a dial or using a select switch, taking into account road surface conditions and vehicle speed.
The output signal xo is outputted to the vehicle height determination circuit 34.

The range defining the upper and lower limits of each target vehicle height is common to each target vehicle height, and for example, an allowable range of ±α is set in advance in the vehicle height determination circuit 34.

Therefore, for example, in the case of target vehicle height zo, the upper limit value of the target vehicle height allowable range is (zo + α), and the lower limit value is (zo − α
).

In addition to manually inputting the target vehicle height via the target vehicle height setting switch 15 as described above, it is also possible to determine the road surface condition from the vehicle height amplitude of the instantaneous value relative to the average value of the output signal of the vehicle height sensor 12. A target vehicle height setting circuit is provided to automatically set a target vehicle height based on the road surface condition and vehicle speed.
You may also output it to .

Here, the control unit 10 will be explained in detail.

Each of the second integration circuits 31 is used to remove disturbances caused by unevenness of the road surface propagating to each wheel 1 to obtain a smoothed vehicle height signal. The time constant τ2 is set to l s so that the disturbance can be smoothed.
It is desirable to set it to ec or higher.

For example, when adjusting the vehicle height from a high-level target vehicle height permissible region to a low-level target vehicle height permissible region, each of the first integrating circuits 30 adjusts the vehicle height with good responsiveness from the start to the end of the vehicle height adjustment. In order to be able to control has been done.

In the vehicle height determination circuit 34, each second integrating circuit 31
An average smoothed vehicle height value or an approximate actual vehicle height value for each of the four vehicle height sensors 12 at predetermined short time intervals is calculated in response to the vehicle height signal X2 from the vehicle height signal X2 or the vehicle height signal X1 from each of the first integration circuits 30. On the other hand, in response to the output signal xO of the target vehicle height setting switch 15, a target vehicle height permissible range is calculated, and the smooth vehicle high value or approximately the actual vehicle height value and the target value are compared and calculated, and as a result, the smooth vehicle high value or approximately the actual vehicle height value is compared with the target value. "1" to energize the refueling solenoid 5a when the high value is lower than the target value.
A signal is output from the amplifier output path 36a to the amplifier AND gate 37a, and the signal is output to the down output path 36b.
0" signal is output, and when the smooth pulley high value or the approximate actual vehicle high value is higher than the target value, the "1" signal (13) is output to the down output path 36b in order to energize the oil draining solenoid 5b. Output Ii for up! A “0” signal is output to &36a.

In the valve drive circuit 35, when the amplifier AND gate 37a outputs a "1" signal, the up power supply path 38a energizes the refueling solenoid 5a, and the oil path switching valve 5 is switched to the refueling position to drive the vehicle. While the high is adjusted to the increasing side, "1" is set from the down AND game 1-37b.
When the signal is output, the oil drain solenoid 5b is energized from the down power supply path 38b, the oil passage switching valve 5 is switched to the oil drain position, and the vehicle height is adjusted to the decreasing side.

The operation of the vehicle height adjusting device having the above structure will be explained below.

First, in a state where vehicle height adjustment is not started, both power supply lines 38a and 38b are not energized, so a "1" signal is not output to the first OR gate 39, and the first OR gate 39 is not energized.
Since the output of 9 is a "0" signal, the coil 33a is not energized (14) from the relay drive circuit 40, and the relay switch 33 is connected to the second integrating circuit 31 side as shown in the figure. The output signal is output to the vehicle height determination circuit 34.

The first input terminal is connected to one input terminal of the second OR gate 43.
A “0” signal is input from the OR gate 39, but the second O
The first OR gate 39 is connected to the other input terminal of the R gate 43.
Since the rOJ signal outputted from the AND gate 3 passes through the delay circuit 41 and is inverted by the inverter 42, the "1" signal is output from the second OR gate 43.
7a to 37b, respectively.

However, the output from the vehicle height determination circuit 34 is
- Since both the AND gates 36b are "0" signals, the outputs of both AND gates 37a and 37b are "0" signals, and the vehicle height is maintained without energizing both solenoids 5a and 5b.

In this way, until the vehicle height adjustment starts, the vehicle height is controlled using the vehicle height signal X2 smoothed by the second integration circuit 31 having a large time constant.

Here, for example, as shown in FIG. 4, at point P, a low level target vehicle height is selected with the target vehicle height setting switch 15, and the vehicle height is set to a high level target vehicle height permissible range (II).

±α) to the low-level target vehicle height permissible region (Lo±α), the vehicle height determination circuit 34 outputs an “l” signal to the down output path 36b to lower the vehicle height. As a result, both the output signals to the down AND gate 37b become "1" signals, so the valve drive circuit 35 energizes the down power supply line 38b, the oil draining solenoid 5b is energized, and the oil path switching valve 5 drains oil. Switched to position.

At this time, a "1" signal is output from the down power supply path 38b to the first OR gate 39, so the output of the first OR gate 39 becomes a "1" signal, and the coil 33a is energized via the relay drive circuit 40. The relay switch 33 is switched to the first integration circuit 30 side, and the vehicle height signal X1 processed by the first integration circuit 30 with a small time constant τ1 is output to the vehicle height determination circuit 34. Using this vehicle height signal X1, Vehicle height is controlled.

Also, at this time, the 10R gate 3 is connected to the second OR gate 43.
Since the "1" signal is directly output from the second OR gate 43, the output of the second OR gate 43 is the "1" signal and the down AND gate) 37
The "1" signal will continue to be output from "b", and the oil draining solenoid 5b will continue to be energized.

By the way, at the time indicated by point P3 in FIG. 4, when the approximate actual vehicle height value (curve C1) based on the vehicle height signal X1, which is approximately close to the actual vehicle height value (curve CO), reaches the target value, the vehicle height determination circuit 34 sends a down signal. Since the "10" signal is output to the output path 36b and the "0" signal is output from the down AND gate 37b, energization to the down power supply path 38b is stopped.

As a result, the output of the first OR gate 39 becomes a "0" signal, the energization to the coil 33a is stopped via the relay drive circuit 40, and the relay switch 33 returns to the second integration circuit 31.
It will be switched to the side. At this time, point P4
The smooth vehicle height value based on the vehicle height signal X2 (curve C2
) is not within the allowable range of the target value, the “1” signal (17) is output again from the vehicle height judgment circuit 34 to the down output path 36b, but the delay circuit 41 and inverter 42 are “1” is then output to the second OR gate 43.
Since the signal is output with a time delay of a predetermined time constant of the delay circuit 41, the second OR is output only during the predetermined time.
Since the gate 43 does not output a "1" signal but an "O" signal, the output of the down AND gate 37b never becomes a "1" signal.

By setting the time constant of the delay circuit 41 to an appropriate value in consideration of the time constant τ2 of the second integrating circuit 31 and the time constant τ1 of the first integrating circuit 30, the high value of the smoothing wheel can be adjusted to the target value. Vehicle height control based on the vehicle height signal X2 can be performed again from the time point P5.

On the contrary to the above, the low level target vehicle height permissible area (L).

The same applies to the case where the vehicle height is adjusted from the high level target vehicle height allowable range (Ho±α).

As described above, according to the vehicle height adjustment device of the above embodiment, the second integration circuit 3 with a relatively large time constant is used until the start of vehicle height adjustment.
The vehicle height is controlled using the vehicle height signal X2 smoothed in step 1, while the vehicle height signal Xi processed by the first integration circuit 30 with a relatively small time constant is used from the start to the end of vehicle height adjustment (18). The vehicle height can be controlled with good responsiveness using

Of course, the first integrating circuit 30 may be omitted and the vehicle height may be controlled using the detection signal X of the vehicle height sensor 12 from the start to the end of vehicle height adjustment.

[Brief explanation of drawings]

Among the drawings, FIGS. 1 to 4 show embodiments of the present invention, in which FIG. 1 is an overall configuration diagram, FIG. 2 is a vertical cross-sectional view of a strut, and FIG. 3 is an enlarged view of the part (■) in FIG. , FIG. 4 is a diagram showing changes in vehicle height during vehicle height adjustment, and FIG. 5 is a diagram corresponding to FIG. 4 in the prior art. 1. Wheel, 2. Strut, 4. Hydraulic drive device, 10. Control unit, 12. Vehicle height sensor,
13...Vehicle body, 15...Target vehicle height setting switch, 1
6. Housing, 30. First integration circuit, 31.
・Second integration circuit. Patent applicant: Toyo Kogyo Co., Ltd. (19) 72- JP-A-209312 (7);
---''Figure 4 Time

Claims (1)

[Claims] +1) A vehicle height adjustment means disposed between the axle support member and the vehicle body, a vehicle height sensor that detects the relative height of the vehicle body to the wheels in m1, and a vehicle height adjustment device that receives the output of the vehicle height sensor. and a vehicle height control means for controlling the vehicle height adjustment means so that the target vehicle height falls within an allowable range, and the vehicle height control means integrates the output signal of the vehicle height sensor at a predetermined time constant until the start of vehicle height adjustment. The vehicle height value obtained through the processing is used for control, and from the start to the end of vehicle height adjustment, the output signal of the vehicle height sensor is integrated with the vehicle height value obtained by integral processing with a time constant smaller than the above time constant. A vehicle height adjustment device for an automobile, characterized in that it is configured to perform control using one of the actual vehicle height value obtained without processing.