JPH0557128B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a vehicle height adjustment device that controls the vehicle height of an automobile to a predetermined measured value or a value within a set range.

(Prior Art) In automobiles, a suspension is interposed between the axles of a vehicle body to reduce the transmission of impact from the road surface, which the axles receive, to the vehicle body. Therefore, the height of the vehicle body relative to the axle, that is, the vehicle height, changes depending on the vertical movement of the axle depending on the road surface condition, the load applied to the vehicle body, and the like. Furthermore, if the vehicle is driven in a state where the amplitude of the vertical movement of the axle is relatively small, or where the sinking of the vehicle body relative to the axle is relatively small, it is inconvenient to set the vehicle height low. However, in situations where the amplitude of the vertical movement of the axle is relatively large, such as when driving on a so-called rough road, or
The vehicle height is set high when the vehicle is traveling with a relatively large amount of sinking of the vehicle body relative to the axle, such as when carrying a large load or when driving with sudden starts or sudden braking. It is hoped that

Therefore, conventionally, a vehicle height adjustment device has been proposed that detects the vehicle height and automatically performs control so that the detected vehicle height takes a predetermined set value or a value within a set range. . For example, Utsukai 47-
An example of such a vehicle height adjustment device is described in Publication No. 22623, and this vehicle height adjustment device uses a sensor that detects the position of a movable object that responds to changes in vehicle height. The vehicle height is adjusted by obtaining a signal that changes according to the vehicle height, that is, a signal representing the vehicle height, and controlling the suspension level based on the signal obtained by integrating this signal. ing.

When such a vehicle height adjustment device controls the vehicle height to a predetermined set level, the vehicle height is adjusted to bring the vehicle height toward the set level, and during this vehicle height adjustment operation, the vehicle height is adjusted. The vehicle height adjustment operation is stopped when the signal from the sensor that generates the signal representing the vehicle height is monitored and the signal from the sensor represents the set level, that is, when the vehicle height reaches the set level. It is done like this.

However, during such vehicle height adjustment operation,
For example, if the vehicle height suddenly changes due to uneven road surfaces and temporarily reaches the set level,
Large-amplitude vibration noise occurs in the signal from the sensor, and this noise causes the signal from the sensor to temporarily represent the set level, resulting in the vehicle height adjustment operation being stopped. In such a case, once the vehicle height has reached the set level, it will deviate from the set level within a short period of time, and the vehicle height adjustment operation will be performed again. However, if the above-mentioned rapid changes in vehicle height are repeated, , the vehicle height adjustment operation is intermittent accordingly. In this way, if the vehicle height adjustment operation is performed intermittently in response to sudden changes in vehicle height due to unevenness of the road surface, etc., unstable vehicle height adjustment accompanied by shocks may occur.
This causes the inconvenience of being done inefficiently.

(Object of the Invention) In view of the above, the present invention performs a vehicle height adjustment operation to change the vehicle height toward the set level when a set level is given, and also adjusts the vehicle height obtained from the vehicle height sensor. When the vehicle height signal indicates that the vehicle height has reached the appropriate setting level, the vehicle height adjustment operation is stopped, and at that time,
During the vehicle height adjustment operation, the vehicle height changes rapidly and temporarily reaches the set level, resulting in large-amplitude noise occurring in the vehicle height signal from the vehicle height sensor, causing the vehicle height signal to temporarily change due to this noise. To provide a vehicle height adjustment device in which the vehicle height adjustment operation is stably performed without being stopped in response to the noise of the vehicle height signal even if a condition that indicates the set level occurs. The purpose is to

(Structure of the Invention) A vehicle height adjustment device according to the present invention includes a vehicle height adjustment mechanism, a vehicle height sensor that detects a vehicle height and issues a vehicle height signal representing the detected vehicle height, and a vehicle height adjustment mechanism that includes a vehicle height sensor that detects a vehicle height and issues a vehicle height signal representing the detected vehicle height. Means for supplying a drive signal for activating the vehicle height adjustment mechanism, and for stopping the supply of the drive signal when the vehicle height signal takes a value representing a set vehicle height when the vehicle height adjustment mechanism is activated, and the operation of the vehicle height adjustment mechanism. Means for detecting the rate of change of the high vehicle height signal and preventing the supply of the drive signal from being stopped even if the vehicle height signal takes a value representing the set vehicle height when the rate of change is greater than a predetermined value. and a vehicle height adjustment control section.

By doing this, when the vehicle height adjustment operation to set the vehicle height to the set vehicle height suddenly changes due to unevenness of the road surface, etc., and the vehicle height temporarily reaches the set vehicle height. This is done stably and smoothly without responding to such temporary fluctuations in vehicle height.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 shows an example of a vehicle height adjustment device according to the present invention. In this example, a vehicle height sensor that detects the vehicle height and generates a vehicle height signal Sx representing the detected vehicle height;
A vehicle height setting section 2 is provided which sends out a set vehicle height signal So representing a set vehicle height. 2 input terminals, respectively. Solenoids 11 and 1 are connected to the first and second output ends of the control unit 10, respectively.
2 are connected.

The solenoids 11 and 12 form part of a drive means for driving the vehicle height adjustment mechanism. This drive means is provided with a hydraulic pump 20 and a motor 21 for driving the hydraulic pump 20, and a pressure oil pipe from the hydraulic pump 20 is connected to a switching valve 22, which is driven by solenoids 11 and 12. Ru. A pressure oil pipe from the switching valve 22 is connected to an accumulator 23 and a shock absorber 24 which also functions as a vehicle height adjustment mechanism.

The shock absorber 24 includes a piston 25 whose tip end is attached to a vehicle body 26, and a cylinder 27 whose tip end is attached to a wheel support part 28. Furthermore, the vehicle height sensor 1 described above is
Although not specifically illustrated here, the vehicle body 26
and a portion related to the axle 29, and detects the vehicle height according to the height of the vehicle body 26 with respect to the axle 29, and generates a vehicle height signal Sx.

The control unit 10 described above receives a vehicle height signal Sx from the vehicle height sensor 1 and a low vehicle height signal from the vehicle height setting section 2.
In order to operate the vehicle height adjustment mechanism formed by the shock absorber 24 so that the vehicle height becomes the set vehicle height in response to the Alternatively, the drive signal u or d is supplied to the solenoid 11 or 12, and the supply of the drive signal u or d to the solenoid 11 or 12 is stopped when the vehicle height signal Sx takes a value representing the set vehicle height when the vehicle height adjustment mechanism is activated. The vehicle height adjustment control section receives the vehicle height signal Sx and detects the rate of change in the vehicle height signal Sx when the vehicle height adjustment mechanism is activated. Even if the signal Sx takes a value that represents the set vehicle height,
It has a built-in vehicle height signal change speed detection section that operates to prevent the supply of the drive signal u or d to the solenoid 11 or 12 from being stopped, and is configured using, for example, a microcomputer.

When the drive signal u is supplied to the solenoid 11 and the solenoid 11 is excited, the hydraulic pump 20
A condition is established in which the pressure oil from the piston 25 flows to the shock absorber 24 side through the switching valve 22, and this pressure oil is supplied to the cylinder 27 through a pressure oil passage hole (not shown) provided in the piston 25. This pushes up the piston 25, and as a result, the vehicle height increases at a predetermined speed. In this case, due to the action of the accumulator 23, the pressure oil acts on the piston 25 with a constant pressure. On the other hand, when the drive signal d is supplied to the solenoid 12 and it is excited, the pressure oil in the cylinder 27 of the shock absorber 24 is
The pressure oil is discharged through the pressure oil passage hole 5 and further via the switching valve 22 to the discharge pipe 30 side. As a result, the piston 25 is pushed down by the weight of the vehicle body 26, and as a result, the vehicle height increases at a predetermined speed. Further, the drive signal u or d is not supplied to either of the solenoids 11 and 12,
When both solenoids 11 and 12 are not energized, the cutoff valve 22 is closed and the pressure oil in the cylinder 27 of the shock absorber 24 is maintained without being changed, and as a result, the current vehicle height is maintained. be done. Although not shown here, a shock absorber 24 that also functions as a vehicle height adjustment mechanism is provided on the left or right side of the vehicle body, and is similarly driven by the same drive means. ing.

In the configuration as described above, the vehicle height is, for example,
The variable range is divided into a plurality of ranges, and the vehicle height value is digitally distributed and represented for each range, and the vehicle height sensor 1 detects the vehicle height value that represents the vehicle height value in the range to which the actual vehicle height corresponds. Signal Sx
is assumed to occur. For example, as shown in Fig. 2, the vehicle height variable range is A,
It is divided into five ranges: B, C, D, and vehicle height values Xa, Xb, and ranges A, B, C, D, and E respectively.
The vehicle height sensor 1 is assumed to generate a vehicle height signal Sx representing one of vehicle height values Xa, Xb, Xc, Xd, and Xe.
In addition, the set vehicle height signal So from the vehicle height setting section 2 is
It represents the vehicle height value corresponding to one of multiple ranges within the vehicle height variable range, for example, the vehicle height values Xa, Xb, Xc, Xd, and Xe shown in Fig. 2.
It is assumed that it represents one of the following.

For example, when the vehicle height is set to take the vehicle height value Xb corresponding to lens B as shown in FIG. 2, the vehicle height value Xb is set as the set vehicle height value.
When a smaller vehicle height value Xd corresponding to range D is given, a vehicle height signal Sx representing the vehicle height value Xb
The vehicle height adjustment control section of the control unit 10, which receives the set vehicle height signal So representing the vehicle height value Xd, determines that the vehicle height value Xd represented by the set vehicle height signal So is smaller than the vehicle height value Xb represented by the vehicle height signal Sx. Detect and
In order to perform a vehicle height adjustment operation that lowers the vehicle height to reach a range corresponding to vehicle height value Xd, solenoid 1
A drive signal d is supplied to 2. As a result, the vehicle height signal Sx is determined by the solid line P in FIG.
As shown, the vehicle height value changes from vehicle height value Xb to vehicle height value Xd via vehicle height value Xc.

At this time, the vehicle height signal change speed detecting section of the control unit 10 that receives the vehicle height signal Sx detects the vehicle height signal Sx.
The time t ₁ from the time tc at which the vehicle height value Xc becomes the vehicle height value to the time td at which the vehicle height value Xd becomes the vehicle height value Xd is detected. This time _t1 is inversely proportional to the rate of change of the vehicle height signal Sx, so the vehicle height signal change rate detection section in the control unit 10 detects the change rate of the vehicle height signal Sx.
The rate of change in Sx will be detected. The vehicle height signal change speed detection section of the control unit 10 detects the time t ₁
A predetermined time T that is smaller than the time T is predetermined, and the time _t1 is greater than the time T, that is, the rate of change of the vehicle height signal Sx is smaller than the predetermined value related to the time T. Detected.

In this case, the vehicle height signal change speed detection section detects that the vehicle height signal Sx of the vehicle height adjustment control section is the vehicle height value Xd.
Therefore, when the vehicle height signal Sx represents the vehicle height value Xd, the solenoid 12 from the control unit 10
The supply of the drive signal d to the vehicle is stopped, and the vehicle height adjustment operation is stopped. As a result, the vehicle height becomes the vehicle height value
range D corresponding to is reached and maintained there.

On the other hand, as described above, the set vehicle height signal So representing the vehicle height value Xd is given to the control unit 1.
A drive signal d is supplied from 0 to the solenoid 12,
When a vehicle height adjustment operation is being performed to lower the vehicle height, if a sudden change in vehicle height occurs due to unevenness of the road surface, the vehicle height signal Sx, for example,
As shown by the broken line Q in the figure, the vehicle height changes rapidly, passing through the vehicle height value Xc and then temporarily reaching the vehicle height value Xd.

At this time, the vehicle height signal change speed detecting section of the control unit 10 that receives the vehicle height signal Sx detects the vehicle height signal Sx.
The time t ₂ from the time t′c at which the vehicle height value Xc becomes the vehicle height value to the time t′d at which the vehicle height value Xd becomes the vehicle height value Xd is detected. This time t ₂ is significantly smaller than the above-mentioned time t ₁ and is less than the predetermined time T set by the vehicle height signal change speed detecting section of the control unit 10 . Then, in the vehicle height signal change rate detecting section of the control unit 10, it is determined that the time _t2 is less than the time T, that is, the change rate of the vehicle height signal Sx is the time T2.
is detected to be greater than or equal to a predetermined value related to .

In this case, a predetermined control signal is supplied from the vehicle height signal change rate detection section of the control unit 10 to the vehicle height adjustment control section, and the vehicle height signal Sx of the vehicle height adjustment control section is supplied.
When the vehicle height signal Sx represents the vehicle height value Xd, the operation of stopping the supply of the drive signal d to the solenoid 12 is prevented, and even if the vehicle height signal Sx represents the vehicle height value Xd, the solenoid 12 from the control unit 10 The supply of the drive signal d to the vehicle continues without any response, so that the vehicle height adjustment operation is not stopped. As a result, the vehicle height is brought to range D corresponding to the vehicle height value Xd and maintained there as a result of the vehicle height adjustment operation, rather than due to sudden fluctuations caused by unevenness of the road surface, etc. It turns out.

Note that a vehicle height value that is larger than the current vehicle height value, for example, vehicle height value Xd, for example, vehicle height value Xb, is given as the set vehicle height value, and therefore, the set vehicle height signal So and the vehicle height signal that represent the set vehicle height value. The vehicle height adjustment control section of the control unit 10 that receives Sx uses the solenoid 11 to perform a vehicle height adjustment operation that raises the vehicle height to reach a range corresponding to the set vehicle height value.
In the case of supplying the drive signal u to the vehicle height signal Sx, the vehicle height signal change speed detecting section of the control unit 10 that receives the vehicle height signal Sx detects the vehicle height signal Sx in the same manner as described above.
For example, if the speed of change of vehicle height signal Sx changes to vehicle height value Xc
It is detected based on the time from the point in time when the vehicle height value Xb is expressed to the point in time when the vehicle height value Xb is expressed, and control regarding stopping the vehicle height adjustment operation is performed in the same way as in the case described above.

An example of a program executed by the microcomputer constituting the control unit 10, which controls the vehicle height adjustment operation, will be described with reference to the flowchart shown in FIG.

First, when the set vehicle height value Xo is inputted by the set vehicle height signal So, in process 40, the vehicle height value x represented by the vehicle height signal Sx is read. Then, a decision 41 determines whether the vehicle height value x is greater than the set vehicle height value Xo, and if not, a decision 42 determines whether the vehicle height value x is smaller than the set vehicle height value Xo. Here, if the vehicle height value .

If the vehicle height value x is smaller than the set vehicle height value Xo as determined in decision 42, the process proceeds to process 43;
The vehicle height range for detecting the rate of change of the vehicle height value x, that is, the rate of change of the vehicle height signal Sx, that is, the vehicle height value X _N of the detection range, and the detected rate of change of the vehicle height signal Sx. A reference time T for determination is set. In this case, the vehicle height value X _N is determined by process 4
It is assumed that the vehicle height value x is between the vehicle height value x read in at 0 and the set vehicle height value Xo. Then, in process 44, a drive signal u is supplied to the solenoid 11 (turning on the solenoid 11) to operate the vehicle height adjustment mechanism and start a vehicle height adjustment operation to raise the vehicle height (increase the vehicle height). Proceed to process 47. As a result, the vehicle height value x changes toward the set vehicle height value Xo.

On the other hand, if the vehicle height value x is larger than the set vehicle height value
, that is, the vehicle height value X _N of the detection range, which is the vehicle height range for detecting the rate of change of the vehicle height signal Sx, and the standard for determining the detected rate of change of the vehicle height signal Sx. Set time T. In this case as well, the vehicle height value _XN is set between the vehicle height value x read in process 40 and the set vehicle height value Xo. Then, in process 46, a drive signal d is supplied to the solenoid 12 (solenoid 1
2 is turned on), the vehicle height adjustment mechanism is activated, a vehicle height adjustment operation is started to lower the vehicle height (vehicle height is lowered), and the process proceeds to process 47. As a result, the vehicle height value x changes toward the set vehicle height value Xo.

Next, in a process 47, the vehicle height value x represented by the vehicle height signal Sx is read, and in a decision 49, it is determined whether the vehicle height value x is equal to the vehicle height value _XN .
Here, if they are not equal, the process returns to process 47, performs the same operation, and repeats this process.

The vehicle height value x is determined by decision 49.
When it is equal to X _N , that is, when the vehicle height value x reaches the vehicle height value X _N , a timer built in the vehicle height signal change speed detecting section is started in process 50.

After that, in process 51, the vehicle height signal is set again.
The vehicle height value x represented by Sx is read, and a decision 52 determines whether the vehicle height value x is equal to the set vehicle height value Xo. Here, if they are not equal, the process returns to process 51, performs the same operation, and repeats this process. If the vehicle height value x is equal to the set vehicle height value Xo as determined in decision 52, that is, when the vehicle height value x reaches the set vehicle height value Xo, in process 53 the time t measured by the timer started in process 50 is read; At decision 54, it is determined whether the time t measured by the timer is greater than the reference time T.

If the timer's measurement clock t is not greater than the reference time T as judged by the decision 54, the speed of change of the vehicle height signal Sx representing the vehicle height value x has been exceeded, and the vehicle height will undergo a sudden vibrational change and the vehicle height value will be changed. It may be assumed that x temporarily becomes the set high value Xo, and the vehicle height value x becomes different from the set vehicle height value Xo within a short period of time, and then becomes the set vehicle height value Xo again, so return to process 51. The operations from process 51 to decision 54 are repeated.

If it is determined at decision 54 that the time t measured by the timer is greater than the reference time T, the vehicle height signal Sx will express the set vehicle height value Xo at a rate of change slower than the predetermined speed. As a result of the vehicle height adjustment operation, the vehicle height value x becomes the set vehicle height value Xo, that is, the vehicle height becomes the set vehicle height value Xo.
Since the range corresponding to has been reached, the process proceeds to process 55, and the supply of the drive signal u or d to the solenoid 11 or 12 is stopped in order to stop the vehicle height adjustment operation (the solenoid 11 or 12 is turned off). ). This completes the vehicle height adjustment.

In the above example, the vehicle height adjustment mechanism is a hydraulic type, but the vehicle height adjustment mechanism is not limited to this, and it goes without saying that the vehicle height adjustment mechanism may be, for example, a pneumatic type. .

(Effects of the Invention) As is clear from the above description, the vehicle height adjustment device according to the present invention allows the vehicle to change the vehicle height given a set vehicle height value so as to take the set vehicle height value. During the height adjustment operation, the vehicle height changes rapidly due to unevenness on the road surface, and temporarily assumes the set vehicle height value. As a result, the vehicle height signal from the vehicle height sensor changes rapidly with a large amplitude. , even if a situation occurs that temporarily indicates the set vehicle height,
Due to such a sudden change in the vehicle height signal, the vehicle height adjustment operation is not temporarily stopped in response to the original part that indicates the set vehicle height value, and as a result of the vehicle height adjustment operation, the vehicle height signal becomes normal. Since the vehicle is stopped only when the set vehicle height value is reached, the vehicle height adjustment to bring the vehicle height to the set vehicle height value can be performed stably and smoothly without any impact. be able to.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram showing an example of a vehicle height adjustment device according to the present invention, FIG. 2 is a diagram used to explain the operation of the example shown in FIG. 1, and FIG. 3 is a diagram similar to that shown in FIG. 1. 2 is a flowchart showing an example of a program executed by a microcomputer used in the example control unit. In the figure, 1 is a vehicle height sensor, 2 is a vehicle height setting section, and 10
is a control unit, 11 and 12 are solenoids, 2
2 is a switching valve, and 24 is a shock absorber.

Claims (1)

[Claims] 1. A vehicle height adjustment mechanism, a vehicle height sensor that detects the vehicle height and generates a vehicle height signal representing the detected vehicle height, and supplies the vehicle height adjustment mechanism with a drive signal for operating the vehicle height adjustment mechanism; means for stopping the supply of the drive signal when the vehicle height signal takes a value representing a set vehicle height when the vehicle height adjustment mechanism is activated; Vehicle height comprising means for detecting a speed of change and preventing the supply of the drive signal from being stopped even if the vehicle height signal takes a value representing a set vehicle height when the speed of change is equal to or higher than a predetermined value. A vehicle height adjustment device configured to include an adjustment control section.