JPH064372B2 - Vehicle height control device - Google Patents

Description

The present invention relates to a vehicle height control device, and more particularly to a vehicle height control device effective when a target vehicle height changes.

[Prior Art] Conventionally, for example, the vehicle height is changed according to the number of passengers or the amount of load, and the vehicle posture is maintained in a good state, or the vehicle height is reduced at high speed to improve maneuverability and stability. The vehicle height is adjusted according to various running conditions, such as improving the riding comfort by raising the vehicle height during continuous rough road travel to prevent bottoming from occurring.

By the way, the vehicle height adjustment in the case where the target vehicle height is changed based on the change of the vehicle speed or the road surface condition or the like is not sufficiently effective unless it is started promptly in consideration of the traveling speed of the vehicle. On the other hand, if the vehicle height is adjusted based on a temporary vehicle height change such as a single unevenness on the road surface, the frequency of the adjustment may increase and hunting may occur in the control. It must be based on the vehicle height detected over a given period of time. However, if the vehicle height increase is determined based on the vehicle height detected for 20 [sec] when entering a rough road, for example, the vehicle speed is set to 4
Even if 0 [km / h], the vehicle travels 222 [m] during the determination time of 20 [sec], and during that time, uncomfortable vibration continues for the occupant.

As a countermeasure against the above-mentioned problems, for example, "vehicle height adjusting device" (Japanese Patent Laid-Open No. 58-49504) is proposed. That is, when the target vehicle height is changed, the vehicle height determination monitoring time is set to be short, and the delay of vehicle height adjustment is shortened.

[Problems to be Solved by the Invention] The vehicle height adjusting device disclosed in Japanese Patent Application Laid-Open No. 58-49504 maintains a state in which the vehicle height detection interval is shortened for a predetermined period when the target vehicle height changes. Therefore, the vehicle height determination monitoring time was shortened. Therefore, immediately after the target vehicle height changes, the vehicle height is adjusted by the vehicle height determination monitoring time of a short span for a predetermined period, and then the vehicle height adjustment is performed by the vehicle height determination monitoring time of a long span in normal times. Was there.

According to such a conventional device, the vehicle height determination time after the target vehicle height change is certainly advanced, so that the vehicle height adjustment toward the target vehicle height after the change is promptly started.

However, on the other hand, the vehicle height judgment is made based on the vehicle height data detected within the vehicle height judgment monitoring time of the short span, and therefore reflects the macroscopic changes in the vehicle height occurring in the long span. Control was impossible.

For example, when considering the control of changing the target vehicle height higher than usual by entering a bad road,
Due to complicated unevenness of the road surface, a complicated vehicle height change in which a short span vehicle height change and a long span vehicle height change are mixed is often generated. In such a case, in the above-described conventional technique, the state in which the vehicle height determination monitoring time of the short span is switched is maintained for a predetermined period. Therefore, during this period, the vehicle height change occurring in the long span is ignored. And finally, based on the transient information,
There is a problem that the determination is frequently switched and the control becomes low in stability.

That is, the conventional device, when the target vehicle height changes,
Although the vehicle height adjustment can be started quickly, the judgment result may change frequently in a transient state such as immediately after entering a bad road, and as a new problem, the control becomes unstable,
There was a problem of causing a feeling of strangeness such as riding comfort.

Therefore, the present invention solves such a problem, can start the vehicle height adjustment quickly when the target vehicle height changes, and is a stable vehicle height control that reflects the vehicle height change in the longest possible span. The purpose is to do.

Configuration of the Invention [Means for Solving Problems] The present invention, which has been made to solve the above problems, detects a vehicle height by detecting a distance between a vehicle body and wheels as a vehicle height, as illustrated in FIG. Means M1, vehicle height changing means M2 for changing the vehicle height in accordance with a command from the outside, and at least a predetermined proportion of the vehicle height detected by the vehicle height detecting means M1 at a predetermined number of times within a predetermined detection period. A determining means M3 for determining whether or not the vehicle height is out of a predetermined vehicle height range including the target vehicle height, and when it is determined that the vehicle is out of the predetermined vehicle height range, the vehicle height is changed toward the target vehicle height. The vehicle height changing means M
In the vehicle height control device including the control means M4 for outputting to 2, further, when the target vehicle height is changed, the detection period for the determination is set shorter than usual, and then the detection period is changed. Is set to be shorter than usual, and thereafter, the detection period setting means M5 for gradually increasing the detection period and returning to the detection period of the normal length is provided, and the detection period setting means M5 sets at least a part of the detection periods. The gist is a vehicle height control device characterized by gradually increasing while overlapping.

The vehicle height detecting means M1 is for detecting the distance between the vehicle body and the wheels as the vehicle height. For example, the displacement of the suspension arm with respect to the vehicle body may be converted into a rotation amount, and the rotation amount may be detected by a potentiometer and output as an analog signal. Further, for example, the rotation amount may be detected by a known rotary encoder and output as a digital signal.

The vehicle height changing means M2 is for changing the vehicle height. However, the vehicle height detection means M1 does not detect the vehicle height change itself by the vehicle height change means M2. The target is only the displacement and amplitude of the vehicle height as the vehicle travels. For example, in an air suspension using an air spring device, a compressor is used to pump air into the air chamber of the air spring device to increase the volume of the air chamber, thereby increasing the vehicle height (HIG).
H) or the air in the air chamber is exhausted by controlling the opening / closing of an exhaust valve to reduce the volume of the air chamber so that the vehicle height is set to a standard state (NORMAL) or a low state (LOW). Can be configured to.
Further, in a suspension of a type that absorbs impact using hydraulic pressure, the vehicle height may be adjusted in multiple steps or steplessly by supplying and discharging hydraulic oil as in the case of air.

The determining means M3 determines whether or not at least a predetermined ratio of the vehicle height detected a predetermined number of times at a predetermined time interval is outside a predetermined vehicle height range including the target vehicle height. Here, the target vehicle height is a vehicle height determined according to various conditions, for example, it may be determined by a driver's operation of a manual switch, and for example, when a continuous rough road is detected, the vehicle height is high. On the other hand, the low vehicle height may be automatically determined according to the traveling state during high-speed traveling.
Further, the predetermined vehicle height range may be, for example, a vehicle height range in which the target vehicle height is a median value and a predetermined width is provided on each of the high side and the low side. The predetermined ratio may be, for example, about 80% of the predetermined number of times. Therefore, the determination means M3 can be configured to calculate the ratio of the vehicle heights detected a predetermined number of times being outside the predetermined vehicle height range, and compare the calculated value with the predetermined ratio to make a determination.

The control means M4 outputs a command for changing the vehicle height toward the target vehicle height when the determination means M3 determines that the vehicle height is out of the predetermined range. For example, when the predetermined ratio of the detected vehicle height is included in the side lower than the target vehicle height, a command to increase the vehicle height is issued, while when it is included in the side higher than the target vehicle height, the vehicle height is decreased. It can be configured to output a command to cause.

When the target vehicle height changes, the detection period setting means M5 sets a detection period for detecting the vehicle height a predetermined number of times shorter than usual, and then, at least part of the detection periods overlap each other. The detection period is gradually increased while returning to the normal detection period.

The determination means M3, the control means M4, and the detection period setting means M5 can be realized as, for example, independent discrete logic circuits. Further, for example, a well-known CPU, a ROM, a RAM, and other peripheral circuit elements may be configured as a logical operation circuit, and each of the above means may be realized according to a predetermined processing procedure.

[Operation] In the vehicle height control device of the present invention, as illustrated in FIG. 1, at least a predetermined proportion of the vehicle height detected by the vehicle height detection means M1 at a predetermined number of times within a predetermined detection period is a target. When the determination means M3 determines that the vehicle height is out of the predetermined vehicle height range including the vehicle height, the control means M4 outputs a command for changing the vehicle height toward the target vehicle height to the vehicle height changing means M2.

Further, the detection period setting means M5 sets the detection period for the above determination to be shorter than usual when the target vehicle height changes, and shortens the time from the change of the target vehicle height to the vehicle height determination. Then, the vehicle height determination by the determination means M3 is promptly performed. After that, the detection period is gradually increased to gradually approach the normal length detection period, and the stability of the vehicle height determination by the determination means M3 is improved. At this time, the detection period setting means M5 gradually increases while overlapping at least a part of the detection periods, so that the time until the next vehicle height determination by the determination means M3 is shorter than the detection period required for the determination. , Despite gradually increasing the detection period, the vehicle height is quickly determined again. Then, finally, the length of the detection period is smoothly restored to the normal length.

Therefore, the vehicle height control device of the present invention, when the target vehicle height is changed, first of all, promptly start the vehicle height change,
After that, it gradually works to capture long-term vehicle height fluctuations without losing speediness, and to make more stable vehicle height adjustments.

The technical problems of the present invention are solved by the action of each component of the present invention as described above.

[Embodiment] A preferred embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 2 shows a system configuration of a vehicle height control device for an automobile using an air suspension which is an embodiment of the present invention.

H1R represents a vehicle height sensor for the front right wheel provided between the front right wheel of the automobile and the vehicle body, and detects the distance between the suspension arm and the vehicle body on the right following the movement of the wheel. H1
L represents a vehicle height sensor for the left front wheel provided between the left front wheel and the vehicle body, and detects the distance between the left suspension arm and the vehicle body. H2C represents a rear wheel vehicle height sensor provided between the rear wheel and the vehicle body, and detects the distance between the rear suspension arm and the vehicle body. Vehicle height sensor H1R, H1
The short cylindrical main bodies 1Ra, 1La and 1Ca of L and H2C are fixed to the vehicle body side, and links 1Rb, 1Lb and 1Cb are provided in a direction substantially perpendicular to the central axes of the main bodies 1Ra, 1La and 1Ca. Turnbuckles 1Rb, 1Lc, 1Cc are rotatably attached to the other ends of the links 1Rb, 1Lb, 1Cb.
The other ends of Rc, 1Lc and 1Cc are rotatably attached to a part of each suspension arm.

A plurality of photo interrupters are provided in the main body of the vehicle height sensors H1R, H1L, H2C, and a disk plate having a slit coaxial with the vehicle height sensor central axis turns the photo interrupters ON / OFF according to changes in vehicle height. When turned off, a change in vehicle height is detected as 4 [bit] vehicle height data and a digital signal is output.

S1L, S1R, S2L and S2R represent air suspensions provided on the left and right front and rear wheels, respectively. The air suspension S2L is provided in parallel with a suspension spring (not shown) between the suspension arm for the left rear wheel and the vehicle body. The air suspension S2L is composed of a main air chamber S2La and a sub air chamber S2Lb that perform an air spring function, a shock absorber S2Lc, and an actuator A2L that changes an air spring constant or a shock absorber damping force. S1L, S1R, and S2R also represent air suspensions having the same configuration and function, and the air suspension S1L is the left front wheel and the air suspension S1.
The R is arranged on the right front wheel, and the air suspension S2R is arranged on the right rear wheel.

10 is each air suspension S1L, S1R, S2L,
It represents a compressed air supply / discharge system for the air spring of S2R, in which a compressor 10b is operated by a motor 10a to generate compressed air. This compressed air is used as a check valve 10c.
Through the air dryer 10d. Check valve 10
The forward direction of c is the direction from the compressor 10b to the air dryer 10d. The air dryer 10d dries the compressed air supplied to each of the air suspensions S1L, S1R, S2L, S2R, protects the air pipes and the components of each of the air suspensions S1L, S1R, S2L, S2R from moisture, and also each air suspension S1.
L, S1R, S2L, S2R main air chambers S1La, S1
Ra, S2La, S2Ra and auxiliary air chamber S1Lb,
The pressure abnormality due to the phase change of water inside S1Rb, S2Lb, S2Rb is prevented. Check valve with fixed throttle 10
The check valve e is forward in the direction from the compressor 10b to the air suspensions S1L, S1R, S2L, S2R. The check valve with fixed throttle 10e has a check valve portion opened when compressed air is supplied, and the check valve portion is closed when compressed air is discharged, and is discharged only from the fixed throttle portion. The exhaust valve 10f is a 2-port 2-position spring offset type solenoid valve. The exhaust valve 10f
Is normally in the position shown in FIG. 2 and is in the shutoff state, but the air suspensions S1L, S1R, S2L,
When the compressed air is discharged from the S2R, it is switched to the communication state shown in the position on the right side of FIG.
Compressed air is discharged into the atmosphere through the air conditioner 0e and the air dryer 10d.

V1L, V1R, V2L, and V2R are air spring supply / exhaust valves that perform a vehicle height adjusting function, and are arranged between the respective air suspensions S1L, S1R, S2L, S2R and the compressed air supply / exhaust system 10 described above. ing. The air spring supply / exhaust valves V1L, V1R, V2L, V2R are 2
It is a port 2 position spring offset type solenoid valve, which is normally in the position shown in FIG. 2 and is in the shut-off state, but when adjusting the vehicle height, it is switched to the communication state shown in the upper side of FIG. . That is, when the air spring supply / exhaust valves V1L, V1R, V2L, V2R are brought into communication with each other,
Main air chambers S1La, S1Ra of each air suspension,
Air can be supplied / exhausted between the S2La, S2Ra and the compressed air supply / exhaust system 10. If air is supplied, the main air chamber S1La,
The volumes of S1Ra, S2La, and S2Ra increase to increase the vehicle height, and if the vehicle is exhausted by its own weight, the volume decreases and the vehicle height decreases. Further, the air spring supply / exhaust valve V1
When L, V1R, V2L, and V2R are shut off, the vehicle height is maintained at the vehicle height at that time. In this manner, the air suspension S1L, S1R, S2L is controlled by controlling the communication between the exhaust valve 10f of the compressed air supply / exhaust system and the air spring supply / exhaust valves V1L, V1R, V2L, V2R. , S2R main air chamber S1La,
The vehicle height can be adjusted by changing the volumes of S1Ra, S2La, and S2Ra.

SE1 is a vehicle speed sensor installed in the speedometer and outputs a signal corresponding to the vehicle speed.

SE2 is a vehicle height setting switch that is disposed in the vehicle compartment and sets the vehicle height in three stages of a high position, a normal position, and a low position.

The signals from the vehicle height sensors H1L, H1R, H2C, the vehicle speed sensor SE1 and the vehicle height setting switch SE2 described above are input to an electronic control unit (hereinafter referred to as ECU) 4. The ECU 4 inputs these signals, processes the data thereof, and performs appropriate control as necessary, so that the air suspension actuators A1L, A1R, A2L, A
2R, air spring supply / exhaust valves V1L, V1R, V2L,
A drive signal is output to the solenoid of V2R, the compressed air supply / exhaust system motor 10a, and the exhaust valve valve 10f.

Next, referring to FIGS. 3 and 4, the air suspension S1
The configuration of the main part of L, S1R, S2L, S2R will be described. Since each air suspension has the same configuration, the right rear wheel air suspension S2R will be described in detail.

As shown in FIG. 3, the air suspension S2R includes a shock absorber S2Rc composed of a well-known piston and cylinder and a shock absorber S2Rc.
And an air spring device 14 provided in association with 2Rc.

Cylinder 12 of shock absorber S2Rc (buffer)
An axle (not shown) is supported at the lower end of a, and the piston rod 12b is provided at the upper end of a piston rod 12b extending from a piston (not shown) slidably arranged in the cylinder 12a. A cylindrical elastic assembly 18 for elastically supporting the vehicle body 16 is provided. In the illustrated example, the shock absorber S2Rc is a conventionally well-known damping force variable shock absorber capable of adjusting the damping force by operating a valve function provided on the piston, and is used for adjusting the damping force. The control rod 20 is rotatably and liquid-tightly arranged in the piston rod 12b via a seal member 22.

The air spring device 14 includes a peripheral wall member 26 including a bottom portion 26a provided with an opening 24 that allows the piston rod 12b to pass therethrough, and a peripheral wall portion 26b rising from an edge portion of the bottom portion.
An upper housing member 28a arranged to cover the peripheral wall member 26 and fixed to the vehicle body, and the housing member 2
It has a chamber 32 constituted by a lower housing member 28b which is connected to the lower end of 8a and whose lower end is open, and a diaphragm 30 which is made of an elastic member and closes the lower end of the lower housing member 28b. The chamber 32 has an opening 34 corresponding to the opening 24 provided in the bottom portion 26a of the peripheral wall member, and is provided with a partition wall member 36 fixed to the bottom portion 26a, whereby a lower main air chamber S2Ra and an upper sub air chamber are provided. It is divided into S2Rb and both air chambers S2Ra and S2Rb are filled with compressed air. The partition wall member 36 is provided with a well-known buffer rubber 40 that can come into contact with the upper end of the cylinder 12a.
0, the openings 24 and 34 are provided in the main air chamber S2Ra.
A passage 42 is formed for communicating with the.

The cylindrical elastic assembly 18 is arranged around the piston rod 12b inside the peripheral wall member 26 which constitutes the inner peripheral wall of the sub air chamber S2Rb by the peripheral wall 26b. Both air chambers S2Ra and S2Rb
A valve device 44 is provided to control the communication of the.

The cylindrical assembly 18 includes an outer cylinder 18a, a cylindrical elastic body 18b, and an inner cylinder 18c that are arranged concentrically with each other.
The cylindrical elastic member 18b is fixed to both the cylinders 18a and 18c. The outer cylinder 18a of the cylindrical assembly 18 is press-fitted into a peripheral wall portion 26b of the peripheral wall member 26 fixed to the vehicle body via an upper housing member 28a. Also,
A valve housing 44a of the valve device 44 that allows the piston rod 12b to pass therethrough is fixed to the inner cylinder 18c, and the piston rod 12b is fixed to the valve housing 44a. It is elastically supported by the vehicle body through a tubular elastic assembly 18. An annular air seal member 46 is sealed between the outer cylinder 18a and the peripheral wall portion 26b, and an annular air seal member 48 is interposed between the piston rod 12b and the valve accommodating body 44a.
Is sealed by. Further, the inner cylinder 18c and the valve housing 4
An air seal member 50 having an annular shape is used to seal the gap between 4a and 4a.

The valve accommodating body 44a is formed with a hole 52 which is open at both ends and extends in parallel with the piston rod 12b, and the rotary valve body 44b is rotatably accommodated in the hole 52.
The rotary valve body 44b includes a main body portion 56a which can be brought into contact with a lower positioning ring 54a arranged at a lower end portion of the hole 52, and a small-diameter operation portion projecting upward from the main body portion to the tubular elastic assembly 18. And a portion 56b. The hole 5
An upper positioning ring 54b, which cooperates with the lower positioning ring 54a to prevent the rotary valve body 44b from falling out of the hole 52, is disposed at the upper end of the second positioning ring 54a. An annular seal base 60 having an inner air seal member 58a and an outer air seal member 58b for sealing the hole 52 is disposed therebetween. Further, between the seal base 60 and the main body portion 56a of the rotary valve body 44b, when the main body portion 56a of the valve body is pressed by the seal base 60 by the air pressure, the rotary movement of the rotary valve body 44b is smoothed. A friction reducing member 62 for reducing the friction is arranged.

Below the cylindrical elastic assembly 18, the openings 24, 34 are provided.
And the main air chamber S2Ra through the passage 42 of the buffer rubber 40.
A chamber 64 communicating with the valve body 4 is formed.
The body portion 56a of 4b is formed with a recess 66 that opens into the chamber 64. Also, the main body portion 56a
A communication passage 68 is formed through the body portion diametrically and crosses the recess 66.

The valve housing 56b that receives the valve body 56a has a fourth
As clearly shown in the figure, a pair of air passages 70 each having one end capable of communicating with the communication passage 68 are provided,
The air passage extends substantially diametrically outward of the hole 52 on the same plane toward the outer peripheral surface of the valve body 44b, and the other end of each air passage 70 is a seat hole 72 on the outer peripheral surface of the valve accommodating body 44a. Open.
Further, between the pair of ventilation passages 70 in the circumferential direction of the hole 52, a ventilation passage 74, one end of which can communicate with the communication passage 68, is directed substantially flush with the ventilation passage 70 toward the outer peripheral surface of the valve housing 44a. To grow. The diameter of the ventilation passage 74 is smaller than that of the ventilation passage 70, and the other end of the ventilation passage 74 has a seat hole 7
At 5, the valve housing 44a is opened to the outer peripheral surface. An annular shape surrounding the outer peripheral surface of the valve accommodating body 44a is formed on the inner peripheral surface of the inner cylinder 18c that covers the outer peripheral surface of the valve accommodating body 44a so as to communicate the seat holes 72 and 75 of the ventilation passages 70 and 74. A groove 76 is formed.

The inner cylinder 18c is formed with an opening 78 that opens to the concave groove 76 that forms an annular air passage, and the tubular elastic member 18b corresponds to the opening 78 in the radial direction of the elastic member. A through hole 80 extending outward is formed. Further, each through hole 80 is opened to the outer peripheral surface of the outer cylinder 18a via an opening 82 provided in the outer cylinder 18a. Therefore, the openings 78 and 82 and the through hole 80 define an air passage provided corresponding to the ventilation passage 70 and penetrating the tubular elastic assembly 18.

The openings 78, 82 and the through hole 80 are connected to the sub air chamber S.
The auxiliary air chamber S2Rb is provided on the outer peripheral surface of the peripheral wall portion 26b of the peripheral wall member that covers the outer cylinder 18a so as to communicate with the 2Rb.
A plurality of openings 84 that are open to the outside are provided at equal intervals in the circumferential direction. In order to communicate all the openings 84 with the openings 78, 82 and the through holes 80, an annular groove 86 surrounding the outer cylinder is formed on the outer peripheral surface of the outer cylinder 18a at a portion where the openings 82 are open. Therefore, the opening 84 is opened to the concave groove 86 forming an annular air passage.

In the example shown in FIG. 4, the openings 78 and 82 and the through hole 80 are provided so as to correspond to the two ventilation passages 70 of the valve housing body 44a, but between the inner cylinder 18c and the valve housing body 44a. Since the annular air passage 76 communicating with the ventilation passages 70 and 74 is formed in the elastic member 18,
The air passage can be formed at a desired position in the circumferential direction of b.

Referring again to FIG. 3, the control rod 20 for adjusting the damping force of the shock absorber S2Rc and the rotary valve body 44b of the valve device 44 are conventionally provided at the upper end portion of the piston rod 12b for rotating operation. A known actuator A2R is provided, and the rotary valve body 44 is provided by the actuator A2R.
b is rotated.

The air suspension S2R, which is configured as described above, has the following operation.

First, the rotary valve body 44b is held in the closed position as shown in FIG. 4, that is, in the position where the communication passage 68 of the valve body does not communicate with any of the ventilation passages 70 and 74 of the valve housing body 44a. Then, the communication between the sub air chamber S2Rb and the main air chamber S2Ra is cut off, so that the spring constant of the suspension S2R is set to a large value.

Further, the actuator A2R allows the communication passage 6 of the valve body to be formed.
When 8 is operated to a position where it communicates with the large-diameter air passage 70 of the valve housing 44a, the main air chamber S2Ra causes the communication passage 68 that communicates with the air chamber, the large-diameter air passage 70, the elasticity. The opening 78, the through hole 80 and the opening 82 of the assembly 18.
Since it is communicated with the sub air chamber S2Rb via and 84, the spring constant of the suspension S2R is set to a small value.

Further, when the communication passage 68 of the rotary valve body 44b is operated to the position communicating with the small-diameter air passage 74 of the valve housing body 44a by adjusting the actuator A2R, the main air chamber S
2Ra is the communication passage 6 communicating with the main air chamber S2Ra.
8, the small-diameter air passage 74, the air passage 76, the opening 78 of the elastic assembly 18, the through hole 80, the opening 82, and the opening 84, and communicates with the sub air chamber S2Rb. Since the small-diameter air passage 74 provides greater air resistance than the large-diameter air passage 70, the suspension S2R
The spring constant of is set to an intermediate value.

Next, the configuration of the ECU 4 will be described with reference to FIG.

The ECU 4 receives a data output from each sensor according to a control program, performs a calculation, and performs processing for outputting a control signal to various devices, a central processing unit (hereinafter referred to as CPU) 4a, the above control program. And a read-only memory (hereinafter referred to as ROM) 4b in which initial data is stored, ECU
Random access memory (hereinafter referred to as RAM) 4c for reading and writing data input to 4 and data necessary for arithmetic control, by a battery so as to retain necessary data after the key switch of the automobile is turned off. The backup random access memory (hereinafter referred to as backup RAM) 4d is configured as a logical operation circuit with an input port (not shown), a waveform shaping circuit provided as necessary, and output signals of the above sensors. A multiplexer for selectively outputting to the CPU 4a, an input unit 4e provided with an A / D converter for converting an analog signal into a digital signal, an output port (not shown), and each of the actuators of the CPU 4a as necessary. A drive circuit that drives according to the control signal And an output unit 4f was. The ECU 4 connects the elements such as the CPU 4a and the ROM 4b, the input unit 4e, and the output unit 4f to the bus line 4g to which each data is sent, the CPU 4a, the ROM 4b, and the RA 4b.
It has a clock circuit 4h for sending a clock signal as a control timing to the M4c or the like at a predetermined interval.

When the vehicle height sensors H1L, H1R and H2C are vehicle height sensors which output digital signals composed of a plurality of photo interrupters used in this embodiment, for example, a buffer 4e is used as shown in FIG. Can be connected to the CPU 4a. Further, for example, in the case of vehicle height sensors H1L, H1R, H2C that output analog signals,
For example, the configuration shown in FIG. 7 can be used. In this case, the vehicle height value is input to the ECU 4 as an analog voltage signal, converted into a digital signal in the A / D converter 4e2, and transmitted to the CPU 4a via the bus line 4g.

Here, the vehicle height conversion value Hm adopted in the embodiment of the present invention
Will be described with reference to FIG. The above-described front wheel vehicle height sensors H1L and H1R detect the distance between the wheels and the vehicle body as the vehicle height. As shown in FIG. 8, the vehicle height is centered on the vehicle height normal position, and when the wheel is riding on a protrusion, the vehicle height is at a low position or full bounce when bounding, while the wheel is riding down into a dent. At the time of rebound, etc., it is output as 16 pieces of data displayed in 4 [bit] from the vehicle height high position to full rebound. The relationship between the output value of the vehicle height sensor and the vehicle height converted value Hm is defined by a map as shown in FIG.
It is previously stored in a predetermined area in the ROM 4b of U4. The ECU 4 converts the output values of the front wheel vehicle height sensors H1L and H1R into vehicle height converted values Hm based on the map, and then uses them for vehicle height control processing described later. The reason why the vehicle height converted values Hm in the full-bound or near the full-rebound are not stipulated at equal intervals is to prevent bottoming or rebound stopper hits.

Next, in one embodiment of the present invention, shortening of the vehicle height detection time and the vehicle height determination time when the target vehicle height changes will be described with reference to FIGS. 9 and 10.

As shown in FIG. 9, when the target vehicle height is set to the vehicle height normal position (time T0 to T10), the vehicle height is detected every time t1 (64 [msec] in this embodiment), and Based on the total vehicle height of 315 [pieces] continuously detected within t3 (about 20 [sec] in this embodiment), the start of vehicle height control is determined as follows. That is, if the number of vehicle heights included in the area indicated by a in the figure (vehicle height conversion value Hm16 or more) is 80% or more of the total number, it is determined that the vehicle height is too high, and the vehicle height is Can be lowered. Further, if the number of vehicle heights included in the region indicated by b in the figure (vehicle height conversion value Hm11 or less) is 80% or more of the above total number, it is determined that the vehicle height is too low, and the vehicle height is Can be raised. Otherwise,
Since the number of vehicle heights included in the dead zone (vehicle height conversion value Hm12 to 15) of the vehicle height normal position shown by c in the figure is large, it is determined that the vehicle height is set near the target vehicle height. The vehicle height does not change.

At time T10, the target vehicle height is changed from the vehicle height normal position to the vehicle height high position by operating the vehicle height setting switch SE2 or responding to a rough road. Then, time t1 (64 [m
sec]) is time t2 (8 [msec]), and time t3 (about 20 [sec]) is time t4 (about 2.5 [se]).
c)), and a total of 315 vehicle heights are detected from time T10 to time T12 after time t4. Since the target vehicle height is changed to the vehicle height high position, the dead area is changed from the area indicated by c in the figure to the area indicated by d (vehicle height converted values Hm16 to 19). On the other hand, since the previous target vehicle height is the vehicle height normal position, the detected vehicle height is 80
The above [%] is included in the area indicated by e in FIG. Therefore, when the vehicle height included in the area e starts to be counted at time T10, and the vehicle height is low at time T11 when the count value exceeds 252 [pieces], which is 80 [%] of the total 315 [pieces], it is determined that the vehicle height is low. The determination is made, and the control for increasing the vehicle height is started from the same time T11. By this control, the vehicle height gradually rises toward the vehicle height high position as shown by the solid line in the figure. Since the target vehicle height does not change after time T12, the vehicle height is detected again every time t1 over time t3, and the vehicle height is determined.

Next, the storage of the detected vehicle height and its update will be described with reference to FIG.

When the target vehicle height changes, the vehicle height is detected at time t2 over the time t4 shortened as described above. Time t
The vehicle height of 315 [units] detected over 4 is time t4.
The continuous 45 [pieces] detected in / 7 are divided into the first block k1, the second block k2 to the seventh block k7 and stored as one block.

Next, when the target vehicle height does not change, the time t4 is extended to the time t3, and the vehicle height is detected every time t1. In this case, the vehicle height of 45 [pieces] detected within the time t3 / 7 is stored in the new first block K1 and 45 of the first block k1.
[Individual] vehicle height is deleted and the second block k2 to seventh
Total number of blocks k7 and new first block K 315
Vehicle height determination is performed based on the individual vehicle heights. Further, when the time t3 / 7 has elapsed, 45 [pieces] of the second block k2
The vehicle height is erased, and the vehicle height determination is continued based on the total vehicle height of 315 of the third block k3 to the seventh block k7 and the new first and second blocks K1 and K2. In this way, the vehicle height of 45 [pieces] is set as one block, and the oldest stored 1 is stored every time the vehicle height for one block is detected.
The vehicle height memory is updated by deleting the block and adding the latest one block.

By the way, the above-described characteristic vehicle height detection, storage and determination of the present invention is executed by the ECU 4 which has already described the vehicle height control processing shown in the flowcharts of FIGS. 11 (A), (B) and (C). It is realized by The vehicle height control process will be described below. The vehicle height control process is repeatedly executed at predetermined time intervals.

First, in step 100, timer T1, counter C1,
Processing for resetting all of C2, C3, C4, C2m, C3m, m and flags F1, F2, F3 is performed. Here, the timer T1 counts vehicle height detection time intervals. The counter C1 counts the total number of detected vehicle heights. The counter C2 counts the number of vehicle heights higher than the dead zone upper limit of the target vehicle height in the total vehicle height detection count. The counter C3 counts the number of vehicle heights lower than the dead zone lower limit value out of the total detected vehicle heights. Counter C
4 is to count the number of vehicles in each block for dividing and storing the detected vehicle height as described above. The counter C2m counts the number of vehicle heights higher than the dead zone upper limit value of the target vehicle height in each block. The counter C3m counts the number of vehicle heights in each block that is lower than the lower limit of the dead zone of the target vehicle height. The counter m counts the number of blocks. The flag F1 is set to a value of 1 immediately after the target vehicle height is changed until the total vehicle height detection count reaches 315 [pieces]. The flag F2 is set to the value 1 when the vehicle height increase control condition is satisfied. The flag F3 is set to 1 when the vehicle height lowering control condition is satisfied.

Next, the routine proceeds to step 102, where the timer T1 starts measuring the vehicle height detection time interval. In the following step 104,
Target vehicle height determination processing is performed. That is, the driver operates the vehicle height setting switch SE2 and the vehicle height sensors H1R and H1.
The target vehicle height is set to the vehicle height high position or the vehicle height low position by the rough road sensitive processing which copes with the case where the vibration of the vehicle body is detected from the output of 1L, or the high speed sensitive processing which is performed based on the output of the vehicle speed sensor SE1. It is determined whether the condition for changing to any of the above is satisfied. In this step,
For example, the target vehicle height is changed to the vehicle height high position at the start of the rough road sensitive processing, and to the vehicle height low position at the start of the high speed sensitive processing.

In the following step 106, it is determined whether or not the target vehicle height has changed in step 104. If the affirmative determination is made, the routine proceeds to step 108, while if the negative determination is made, the routine proceeds to step 112. In step 108, each counter C1, C2, C3, C4, m is started to determine the current vehicle height based on the latest detected vehicle height based on the change in the target vehicle height and to start the control for shifting to the target vehicle height. , C2m, C3m are reset to prepare for new vehicle height detection. Continued Step 1
In 10, it is determined in step 106 that the target vehicle height has changed, so the flag F1 is set to the value 1. Next, the routine proceeds to step 112, where it is determined whether or not the flag F1 is set, and if a positive determination is made, step 114
If, on the other hand, a negative decision is made, the operation proceeds to step 116. In step 114 that is executed when the target vehicle height changes, it is determined whether or not the measured value of the timer T1 is 8 [msec] or more, and the same steps are repeated until 8 [msec] elapses. After that, the process proceeds to step 118. This is performed because the vehicle height detection time interval is shortened to 8 [msec] with the change of the target vehicle height. On the other hand, step 1 executed when the target vehicle height does not change
At 16, it is determined whether the measured value of the timer T1 is 64 [msec] or more, and the same steps are repeated until 64 [msec] has elapsed, and then the process proceeds to step 118. In this case, since the target vehicle height does not change, the vehicle height detection time interval is set to 64 [msec].

In step 118, the timer T1 is reset and
The process of starting the timing again is performed. Continued Step 1
At 20, the process of detecting the vehicle height from the vehicle height sensors H1L, H1R, H2C is performed. Here, the vehicle height may be detected as the maximum value of the above-mentioned sensors, may be the average value of the left and right sides, or may be detected by a specific vehicle height sensor. Next, the routine proceeds to step 122, where the vehicle height sensor output detected at step 120 is converted into a vehicle height conversion value Hm based on the map shown in FIG.

Next, in step 124, 1 is added to the value of the counter C4 that counts the number of detected vehicle heights in each block. In the following step 126, it is determined whether or not the count value of the counter C4 is equal to the detected vehicle height 45 [pieces] for one block. If the affirmative determination is made, the process proceeds to step 128, and if the negative determination is made, the step is performed. Proceed to 130, respectively. In step 128 executed when the vehicle height is detected by the number of blocks, the counter C4 is reset to the value 0, and the value of the counter m is set to 1 in response to the increase in the number of blocks.
Just add.

In step 130, it is determined whether or not the vehicle height converted value Hm calculated in step 122 exceeds the dead zone upper limit value of the target vehicle height, and if an affirmative determination is made, the routine proceeds to step 132, where it is currently detected. Counter C2 that counts the number of vehicle heights higher than the dead zone upper limit value in the m-th block
After adding 1 to m, the process proceeds to step 138. on the other hand,
If it is determined in step 130 that the vehicle height converted value Hm is less than or equal to the dead zone upper limit value, the process proceeds to step 134.
In step 134, it is determined whether or not the vehicle height converted value Hm is lower than the dead zone lower limit value of the target vehicle height, and if an affirmative decision is made, the operation proceeds to step 136, in which the currently detected mth block is insensitive. After adding 1 to the counter C3m that counts the number of vehicle heights lower than the region lower limit value, the process proceeds to step 138. On the other hand, when it is determined in step 134 that the vehicle height converted value Hm is equal to or higher than the dead zone lower limit value,
The process proceeds to step 138 without adding any of the counters C2m and C3m.

In step 138, after adding 1 to the value of the counter C1 for counting the total number of vehicle height detections. In step 140, it is determined whether the value of the counter C1 is equal to 315 [pieces]. That is, it is determined whether or not the total number of vehicle heights detected reaches the number 315 [pieces] required for vehicle height determination. If the determination is affirmative, the procedure proceeds to step 142, while if the determination is negative, the procedure is step Proceed to 158.

In step 142, which is executed when the total number of detected vehicle heights reaches 315 [pieces], the oldest one block of the stored vehicle heights is erased to delete the latest one block as described above. In order to newly detect the vehicle height, the value of the counter C1 is set to a value 270 obtained by subtracting 45 [pieces] for one block from the total number of 315 [pieces] and is necessary for the latest vehicle height determination after the target vehicle height change. The flag F1 is reset to the value 0 only when the vehicle height of 315 [pieces] is detected. Continued Step 1
At 44, a counter C2m that counts the number of vehicle heights higher than the dead zone upper limit value in each of seven consecutive blocks
Of the vehicle height detection total number 315 [pieces], the total number of vehicle heights higher than the dead zone upper limit value is set in the counter C2. Next, the procedure proceeds to step 146, where all the count values of the counter C3m that counts the number of vehicle heights lower than the dead zone lower limit value in each of the seven consecutive blocks are added to obtain the total number of vehicle heights lower than the dead zone lower limit value. Counter C3
Set to.

In the following step 148, it is judged whether or not the value of the counter C2 is 252 [pieces] which is 80 [%] of the total vehicle height detection number 315 [pieces] or more, and if a positive determination is made, the routine proceeds to step 150. In step 150, the number of vehicle heights exceeding the dead zone upper limit value of the target vehicle height is 80% or more of the total number, so that the vehicle height lowering control condition is satisfied in order to lower the vehicle height to approach the target vehicle height. The flag F3 is set to a value of 1 and the flag F2 is set to indicate that the vehicle height increase control condition is satisfied.
Is reset to the value 0, and the process proceeds to step 158. If it is determined in step 148 that the value of the counter C2 is less than 252 [pieces], the process proceeds to step 152. At step 152, the value of the counter C3 is 252.
It is determined whether or not the number is [pieces] or more, and if an affirmative determination is made, the process proceeds to step 154. In step 154, the total number of vehicle heights below the lower limit of the dead zone of the target vehicle height is 80.
Since there is more than [%], in order to raise the vehicle height to approach the target vehicle height, the flag F2 indicating the vehicle height increase control condition is set to the value 1, and the flag F3 indicating the vehicle height decrease control condition is set to the value. After resetting to 0, proceed to step 158. On the other hand, in step 152, the value of the counter C3 is 2
If it is determined that the number is less than 52 [pieces], step 1
Proceed to 56. Since it is not necessary to change the vehicle height in step 156 because the current vehicle height is near the target vehicle height, after resetting both the flags F2 and F3 to the value 0, step 1
Proceed to 58.

In step 158, the above steps 150, 154, and
Flags F2 and F set or reset in 156
Vehicle height changing processing based on 3 is performed. That is, when the flag F2 indicating that the vehicle height increase control condition is satisfied is set, the vehicle height increase control is started by the supply of compressed air by the compressed air supply / exhaust system 10, while the flag indicating that the vehicle height decrease control condition is satisfied. When F3 is set, the vehicle height lowering control is started by the compressed air supply / exhaust system 10 exhausting the compressed air. When both of the flags F2 and F3 are reset, the vehicle height is not changed.
After executing step 158, the control shifts to step 104, and steps 104 to 158 are repeatedly executed again.

In this embodiment, vehicle height sensors H1L, H1R, H
2C, the ECU 4, and the processing executed by the ECU 4 (step 120) function as the vehicle height detection means M1,
Compressed air supply / exhaust system 10 and air suspension S1L, S
1R, S2L, S2R correspond to the vehicle height changing means M2. Further, of the ECU 4 and the processing executed by the ECU 4 (steps 130, 132, 134, 36, 1
44, 146, 148, 152) is the determination means M3, and (steps 150, 154, 158) is the control means M3.
4 (steps 106, 110, 112, 11
4) respectively function as the detection period setting means M5.

As described above, in the present embodiment, when the target vehicle height is changed, the vehicle height detection time interval is changed from 64 [msec] to 8 [msec].
It is shortened to [msec] and used for vehicle height determination. While maintaining the total vehicle height at 315 [pieces], the current vehicle height is determined for about 2.5 [sec], and control toward the target vehicle height is started.

For this reason, when the target vehicle height changes, the same number of vehicle heights as when the target vehicle height does not change is detected and determined in a short time, so that quick vehicle height change control based on accurate vehicle height determination becomes possible.

Further, in accordance with the above effect, the bottoming can be prevented by the rapid vehicle height increase control during the rough road sensitive processing, while the vehicle posture can be stabilized by the rapid vehicle height decrease control during the high speed sensitive processing.

Further, the detected total vehicle height of 315 [pieces] is divided into blocks of 45 [pieces] and stored, and the oldest one block is erased and the latest one block is added at the same time to update the storage. Therefore, the accuracy of the vehicle height determination can be maintained at a high level particularly during the execution of the vehicle height changing process after the change of the target vehicle height.

When the target vehicle height does not change, the past 6
Since the vehicle height is determined based on the vehicle height for one block and the newly detected data for one block, it is possible to prevent the vehicle height from being erroneously determined due to a temporary vehicle height change.

In addition, in the embodiment, after the target vehicle height is changed, it is about 2.5 [sec] until the first vehicle height determination, and thereafter about 2.9 [sec].
The vehicle height is determined every time. Looking at the length of the detection period at this time, the detection period for the first vehicle height determination is about 2.
5 [sec], and thereafter about 5.0 [sec], 7.6 [s
ec], 10.1 [sec], and so on, and finally becomes about 20.2 [sec]. That is, in the embodiment, after the target vehicle height is changed, the time to reach the next vehicle height determination is not increased even though the detection period is gradually increased. Therefore, the stability of the vehicle height determination is gradually improved while maintaining the promptness of the vehicle height determination.

Although the embodiments of the present invention have been described above, the present invention is not limited to such embodiments, and it goes without saying that the present invention can be implemented in various modes without departing from the scope of the present invention. .

As described above in detail, the vehicle height control device of the present invention sets the detection period for vehicle height determination shorter than usual when the target vehicle height changes, and after the change of the target vehicle height, Since the time to reach the vehicle height determination is shortened, the vehicle height determination is quickly performed and the vehicle height control is started quickly.

Further, after setting the detection period to be short, the detection period is gradually increased to gradually approach the normal length, and is smoothly returned to the normal length. Gradually improve, and more reliable vehicle height control will be performed.

Further, since at least a part of the detection period is gradually increased while overlapping with each other, the time until the next vehicle height determination is short even though the above detection period is gradually increased, and the vehicle height determination can be performed quickly. Is not lost.

Therefore, for example, when the vehicle enters a bad road, the vehicle height is quickly increased to improve the riding comfort, while when the vehicle is moved to a high-speed running state, the vehicle height is quickly lowered to improve maneuverability. Stability can be maintained at a high level.

[Brief description of drawings]

FIG. 1 is a basic configuration diagram illustrating the content of the present invention, FIG. 2 is a system configuration diagram of an embodiment of the present invention, FIG. 3 is a sectional view of the same air suspension, and FIG. A-
Sectional view A, FIG. 5 is a block diagram for explaining the configuration of an electronic control unit according to an embodiment of the present invention, and FIGS. 6 and 7 are block diagrams showing the vehicle height sensor input circuit of the same.
FIG. 9 is an explanatory diagram showing a map that defines the relationship between the vehicle height conversion value and the vehicle height sensor output, FIG. 9 is an explanatory diagram for explaining the change in the vehicle height detection time and the determination time, and FIG. 10 is the vehicle height. FIG. 11 (A), (B), (C) illustrating the update of the memory of FIG.
3 is a flowchart of an embodiment of the present invention. M1 ... Vehicle height detecting means, M2 ... Vehicle height changing means M3 ... Judging means, M4 ... Control means M5 ... Detection period setting means H1L, H1R, H2C ... Vehicle height sensors S1L, S1R, S2L, S2R ... Air suspension 10 ... Compression Air supply / exhaust system 4 ... Electronic control unit (ECU) 4a ... CPU

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Masami Ito 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation (56) References JP 59-75816 (JP, A) JP 60-255515 (JP, A) JP-A-58-49504 (JP, A)

Claims (2)

[Claims] 1. A vehicle height detecting means for detecting a distance between a vehicle body and a wheel as a vehicle height, a vehicle height changing means for changing a vehicle height in accordance with a command from the outside, and a vehicle height detecting means within a predetermined detection period. Determining means for determining whether or not at least a predetermined ratio of vehicle heights detected a predetermined number of times at predetermined time intervals is outside a predetermined vehicle height range including the target vehicle height; and determining that the vehicle height is outside the predetermined vehicle height range. In the vehicle height control device including a control unit that outputs a command to change the vehicle height toward the target vehicle height to the vehicle height changing unit, if the target vehicle height further changes, Includes a detection period setting means for setting the detection period for the above determination to be shorter than usual, and thereafter gradually increasing the detection period to return to a detection period of a normal length, the detection period setting means comprising: At least part of the detection period is exceeded Vehicle height control apparatus characterized by gradually increasing while wrapped. 2. The detection period setting means changes at least the predetermined time interval of the predetermined time interval and the predetermined number of times to a shorter time to make the detection period for the determination shorter than usual. The vehicle height control device according to claim 1.