JPH01141111A - Car height adjustment control method - Google Patents

Abstract

PURPOSE:To enhance control accuracy by determining a value varying in the porality to be input according to a car height value bordering a dead zone corresponding to a car height objective value, counting this value corresponding to a detected car height value and performing car height control comparing the discrete value with the setting value subject to a car stopping state. CONSTITUTION:Based on the output of car height sensors 30a and 30b for the front wheel side and rear wheel side, air valves 19 and 20 are controlled by means of an controller 29. This supplies and exhausts compressed air to and from air chambers 15 to 18 for adjusting car height. In this case, a dead zone having upper and lower limit as objective car speed is set to determine the value (+1, -1) varying in the porality to be input according to a car height. This value corresponding to the car height detected every predetemined time is counted one by one for computing the total number of counting, and when the total number of counting reaches the first setting value, the car height control starts and when the latest total number of counting reaches the second setting value (less than the first setting value), car height control stops. The first setting value and second setting value select different value based on whether a car is making a stop or not.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a vehicle height adjustment control method capable of detecting and processing data necessary for adjusting the vehicle height of an automobile and maintaining the vehicle height suitably.

(Prior Art) As a conventional vehicle height adjustment control method, there is a method of comparing a vehicle height target value with an average value of vehicle height detection data, and performing vehicle height adjustment control based on the data.

In this method, for example, as shown in FIG. 6, the vehicle height is detected as an analog quantity from a vehicle height sensor, and this detected vehicle height is
The data is converted into D and captured as a continuous digital quantity at a sample interval Δt. Then, the average Xn of n pieces of data (X, ~Xn) within a certain time T is calculated, and the latest detected vehicle height Calculate the average value Xn++, and calculate the average vehicle height Xn, Xn+ while updating it sequentially.
+.

Outputs Xn+2.

Target vehicle height
0 is set, and this upper limit set value is set to H1, and the lower limit set value is set to L. After setting this target, the vehicle height control circuit sequentially adjusts the updated detected vehicle height value Xi and compares it with the upper and lower set values H and L, as shown in FIG. Then, this detected value Xl
When is smaller than the lower limit set value, the vehicle height increase signal circuit is driven, and when it is greater than the upper limit set value, the vehicle height lower signal circuit is driven. Each signal circuit also has a target value X. Depending on which comparison is made, driving continues until the target vehicle height x0 has not been achieved, and when the target vehicle height X0 is reached, the stop circuit is activated (see Japanese Patent Laid-Open No. 185610/1983).

(Problems to be Solved by the Invention) However, according to the above conventional vehicle height adjustment control method,
The vehicle height target value and the average value of the vehicle height detection data are compared, and the vehicle height adjustment is completed when the vehicle height target value and the average value of the vehicle height detection data match. There was a problem in that the value was set too high, requiring correction accordingly, which caused hunting.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a vehicle height adjustment control method that can improve the accuracy of vehicle height adjustment by performing predictive control of the vehicle height.

(Means for Solving the Problems) In order to solve the problems of the conventional example, the vehicle height adjustment control method according to the present invention is performed as follows.

A value with a different polarity to be read depending on the vehicle height value is predetermined, with a dead zone set for the vehicle height target value as the boundary.

The vehicle height value is detected at regular intervals, and the values corresponding to the vehicle height value are sequentially counted, and the total number of counts ranging from 0 to the first set value is calculated.

When the total count reaches the first set value, vehicle height control is started, which changes the vehicle height, and the latest total count reaches the first set value.
When a second set value smaller than the set value is reached, vehicle height control is ended.

At this time, different values are selected for the first and second set values depending on whether the vehicle is stopped or not.

(Function) Since the present invention is configured as described above, instead of directly comparing the vehicle height target value and the vehicle height detection data, the total count is determined based on the predetermined value a while the vehicle is stopped or traveling. Predictive control is performed to start or end vehicle height control depending on whether different set values have been reached.

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

FIG. 2 shows an air suspension for a vehicle to which the embodiment is applied.

Front wheel shock absorber interposed between the vehicle body and the wheels 11.12. and rear wheel shock absorber 13.1
4 are provided with air chambers 15, 16, 17, and 18, respectively, to form air springs.

These air chambers 15, 16, 17, 18 communicate with one air valve for adjusting the vehicle height of the front wheels or the air valve 20 for adjusting the vehicle height of the rear wheels, and these air valves 19, 20 are connected to air pipes 21.
It is connected to the near compressor 22 via. The air pipe 21 includes a dryer 2 that removes moisture from compressed air.
3 and the residual pressure valve 24, and the accumulator 2
Air supply valve 2 for supplying air in air pipe 21 into air pipe 21
6 is connected to an exhaust valve 27 and a filter 28 for discharging itchy air in the air pipe 21 to the outside.

Signals from a vehicle height sensor 30a that detects the vehicle height of the front wheels, a vehicle height sensor 30b that detects the vehicle height of the rear wheels, etc. are input to the vehicle height adjustment controller 29, and vehicle height adjustment control is performed based on these signals. Signals are calculated and air valves 19.20. Air supply valve 26. Controls the opening and closing of the exhaust valve 27. The compressed air is then supplied to the air chamber 15.16.1 via the air valve 19.20.
7. The vehicle height is adjusted by moving the vehicle height up or down by injecting or discharging it at 18.

In a vehicle having such a suspension mechanism,
When the vehicle height between the vehicle body and a wheel or axle changes, the vehicle height sensor outputs a code corresponding to the vehicle height as a detection signal. That is, when the vehicle height changes as shown in FIG. 3, the target vehicle height X. A dead band is set as
When the lower limit setting value is L, the detection signal from the vehicle height sensor is output in three ways: the range a which is higher than the upper limit setting value, the range b which is the dead band, and the range C which is lower than the lower limit setting value. Ru.

Part 1 regarding vehicle height front elevation control to increase vehicle height
This will be explained with reference to the flowchart shown in the figure.

First, a vehicle speed signal is detected by a vehicle height sensor to determine whether the vehicle is stopped or running. and a set value Nu related to the start of the vehicle height adjustment operation.

Nu' is selected, and detailed explanation will be given later.

Next, the vehicle height value is adjusted for a certain period of time Δt (unsprung resonance □
Detect every value that can be sampled up to the vicinity.

Then, if the vehicle height is within the range of C above, set (+1) to b
Alternatively, if it is within the range a, (-1) is sequentially counted by the front raising operation counter provided in the two vehicle height adjustment controllers. In vehicle height increase control, values (+1) and (-1) whose polarity differs depending on the vehicle height value are read, with the lower limit set value of the dead zone provided for the vehicle height target value as the boundary.

That is, when the vehicle height changes as shown in FIG. 3, (+1) is counted in the α region and (-1) is counted in the β region. Therefore, in the α region, the total count n increases Δ by one every time, and in the β region, the total count n decreases Δ by one every time. However, the total number of counts n is (0)
If it is below, it is not counted and n=o is maintained.

Then, when the total count n reaches Nu, which is a predetermined set value for the vehicle height target value, vehicle height control for raising the vehicle height is started. Therefore, unless the vehicle height continues to be lower than the lower limit setting value for a certain period of time (NuXΔ time), the operation to raise the vehicle height is not started. In addition, if the total number of counts n is greater than or equal to Nu, no further counting is performed and n
= Maintain Nu.

When the vehicle height raising operation is started, the vehicle height increases, so the α area decreases and the β area increases. Therefore, the number of times (-1) is counted increases, and the total number of counts n decreases. When the total count n reaches Nu', which is a set value smaller than Nu, the vehicle height raising operation is completed and the front raising operation counter is reset (<n=o).

The set value Nu is a value for averaging the vehicle height, but as is clear from Fig. 4, the total number of counts n is equal to the set value N.
Since vehicle height control is not performed until u is reached, this value represents a delay in the start of the adjustment operation (when Nu is small, the total count n reaches Nu in a short time, so the delay in the adjustment operation is reduced). While the vehicle is stopped, this delay should be as small as possible (however, it should not be extremely small to prevent unnecessary adjustment operations due to repeated loading and unloading of people and luggage). Furthermore, while the vehicle is running, it is better for Nu to be relatively large in order to average the vehicle height, and the optimum value of Nu is different between when the vehicle is stopped and when the vehicle is running.

In this embodiment, in consideration of this point, before counting, a vehicle height sensor detects a vehicle speed signal to determine whether the vehicle is stopped or running, and different values of Nu can be selected. In other words, while driving, Nu=N is a relatively large value.
Select u, and if the vehicle is stopped, select Nu, the smaller value Nu=Nu.

Along with this, Nu' can also be selected when the vehicle is stopped or when the vehicle is running. The set value Nu' is related to NU,
From the vehicle height adjustment speed Vu and the dead zone width, it is determined as follows.

Time t required to reach 1/2 of dead zone at vehicle height adjustment speed Vu =
(b/2)/VU If the number of counts during the time ahead is N=t/Δt, then Nu'=Nu-N.

To simplify the explanation, taking as an example a case where there is no complicated vehicle height fluctuation (when the vehicle is stopped), the relationship between the vehicle height fluctuation, the total count n of the counter, and the presence or absence of the raising operation signal is expressed as follows. It will look like Figure 4.

At the left end of Figure 4, the vehicle height is lower than the lower limit setting value, so Δ
is counted by (+1) every hour using a counter, and at the point in time (a) when the total count n reaches Nu, the vehicle height raising operation starts. The vehicle height increases with the start of the raising operation, but since the vehicle height is lower than the lower limit setting value, this is the area where (1,000 1) should be counted.

At this time, the total number of counts n has already reached Nu, so it will not be counted any more. After that, the vehicle height will reach the point (mouth) where it becomes equal to the lower limit setting value, and it will enter the dead zone area where it counts (-1). enter. In this region, the counter counts Δ by (-1) every time, so the total number of counts n decreases. Then, the total count n reaches Nu' (
At point c), the vehicle height raising operation is completed and the total count of the counter is reset.

The counter prepares to start counting again, but at this time the vehicle height is at the middle position of the dead zone (target vehicle height), and is (-1).
However, since the total number of counts is n=o immediately after reset, this state is maintained.

The above describes the front raising operation, but the vehicle height adjustment controller also includes a front lowering operation counter,
A counter for rear raising operation and a counter for rear lowering operation are provided, and each performs the same function.However, in the case of lowering operation, the upper limit setting value H of the dead zone set for the target vehicle height value is set. As a boundary, if the vehicle height is higher than this (+1
), if it is low, count (-1).

When raising the vehicle height in vehicle height adjustment control,
A vehicle height adjustment control signal is output from the vehicle height adjustment controller 29, and based on this signal, the air valve 19 or 20 is opened to operate the near compressor 22, and the air is supplied to the front side air chamber 15, 16 or the rear side. When lowering the vehicle height, the vehicle height adjustment controller 29 outputs a vehicle height adjustment control signal, and this signal causes the air valve 19 or the air to be lowered. This is done by opening the valve 20, opening the exhaust valve 27, and discharging air from the front air chamber 15, 16 or the rear air chamber 17, 18.

To end the vehicle height raising/lowering operation, press the air valve 19.2.
0 is closed.

FIG. 5 shows another embodiment of the method of the invention.

In this embodiment, when front or rear vehicle height control is completed, a counter for front raising operation, a counter for front lowering operation, and a counter for rear raising operation.

All counters for rear lowering operation are reset.

Now, considering the time when the front raising operation starts and ends, the front lowering operation counter, the rear raising operation counter, and the rear lowering operation counter count the value of (+1) or (-1). It's inside.

However, this count data is based on data while the front is being raised and the vehicle height is changing. Therefore, if this data is continuously counted and the vehicle height is controlled, the control will be based on a value that largely combines past data while the vehicle height is changing.

Therefore, when a certain operation (for example, front raising operation) ends, not only the front raising operation counter that controls that operation but all other counters are reset even if they are still counting. . Therefore, the reset counter starts counting again from that point on, and control can be performed based on data at the new vehicle height rather than past data, and the accuracy of vehicle height control becomes even better.

In the above embodiments, the vehicle height is adjusted by means of pneumatic pressure, but it may also be a means using hydraulic or mechanical power.

Further, in this embodiment, a vehicle speed sensor is used to determine whether the vehicle is stopped or running, but other methods may be used as long as it is possible to determine whether the vehicle is stopped or running.

(Effects of the Invention) The present invention predetermines a value whose polarity differs depending on the vehicle height value, with a dead zone set for the target vehicle height value, and detects the vehicle height value at regular intervals, and detects the value corresponding to this vehicle height value. The vehicle height control is started when the total number of counts reaches a first set value, which is the upper limit of counting, and the vehicle height changes as a result, and the latest total number of counts is smaller than the first set value. The vehicle height control is terminated when a second set value is reached, and the first and second set values are configured to select different values depending on whether the vehicle is stopped,
Rather than directly comparing the vehicle height target value and vehicle height detection data, the vehicle height is controlled based on whether or not the total count reaches a predetermined set value with respect to the target value, which differs depending on whether the vehicle is stopped or traveling. performs predictive control to start or end.

Therefore, predictive control of the vehicle height prevents hunting, eliminates the need to correct the vehicle height, and reduces the time it takes to start vehicle height control when the vehicle is stopped compared to when the vehicle is moving. This allows for optimal vehicle height control and improves the accuracy of vehicle height adjustment.

[Brief explanation of the drawing]

Fig. 1 is a flowchart showing vehicle height increase control in an embodiment of the method of the present invention, Fig. 2 is an explanatory diagram of the air suspension mechanism in the embodiment, and Fig. 3 shows the value counted by the counter and the vehicle height in the embodiment. FIG. 4 is an explanatory diagram showing the relationship between changes in vehicle height, the total count of the counter, and the presence or absence of an upward movement signal in an embodiment. FIG. 5 is another embodiment of the method of the present invention. Flowchart diagram showing vehicle height increase control of
FIG. 6 is a graph showing the actual vehicle height and sampling method in the conventional vehicle height control method, and FIG. 7 is a flowchart of the conventional vehicle height control method. 11.12.13.14・Old・Shock absorber 1
5.16.17.18... Air chamber 19.20.
... Air valve 22 ... Near compressor 26 ... Air supply valve 27 ... Exhaust valve 29 ... Vehicle height adjustment controller 30a, 30
b...Vehicle height sensor November 27, 1988 Figure 1 Figure 3 Figure 5

Claims (1)

[Claims] A value with a different polarity to be read depending on the vehicle height value is predetermined, with a dead zone set for the vehicle height target value as the boundary, and the vehicle height value is detected at regular intervals and the values corresponding to this vehicle height value are sequentially counted. Calculate the total number of counts that take a value from The vehicle height control is terminated when a second set value smaller than the set value is reached, and different values are selected for the first and second set values depending on whether or not the vehicle is stopped. Vehicle height adjustment control method.