JP3010933B2 - Vehicle suspension characteristic control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for controlling suspension characteristics of a vehicle in which the suspension characteristics are set to the hard side when the vehicle is suddenly braked so that the dive of the vehicle body is suppressed.

[0002]

2. Description of the Related Art Conventionally, this kind of vehicle is disclosed in
As disclosed in Japanese Patent Application Laid-Open No. 3-34213, an anti-lock brake device for avoiding locking of wheels at the time of sudden braking is provided, and a suspension mechanism capable of changing the suspension characteristics of a vehicle to soft or hard is provided. By setting the suspension characteristics to the hard side when the lock brake device is operated, the dive of the vehicle body is suppressed, and the running stability of the vehicle at the time of sudden braking is improved.

[0003]

In general, when the suspension characteristics of the vehicle are switched to the hard side, the change in the posture of the vehicle body is suppressed and the running stability of the vehicle is improved, but the riding comfort of the vehicle is improved. Tend to disappear. Therefore, in the conventional device described above, even when the degree of sudden braking of the vehicle is small and the running stability of the vehicle is sufficiently ensured by the anti-locking brake device, the suspension characteristics of the vehicle are switched to the hard side. Although the running stability of the vehicle is improved more than necessary, there is a problem that the riding comfort of the vehicle is deteriorated. The present invention has been made in consideration of the above problems comprehensively, and its object is to control the suspension characteristics of the vehicle in accordance with the state of the anti-lock brake device so that the running stability of the vehicle is given the highest priority and It is an object of the present invention to provide a suspension characteristic control device for a vehicle in which the ride comfort of the vehicle is improved as much as possible.

[0004]

In order to achieve the above object, a structural feature of the present invention is applied to a vehicle equipped with an anti-lock brake device, and a suspension mechanism capable of changing a suspension characteristic of the vehicle; Sudden braking detecting means for detecting the degree of sudden braking of the vehicle, comparing means for comparing the detected degree with a predetermined reference value, and controlling the suspension mechanism in accordance with the comparison result of the comparing means to determine the degree of detection. A switch control means for setting the suspension characteristic to a soft side when the detection value is smaller than the reference value and switching the suspension characteristic to a hard side when the detection degree is larger than the reference value; A reduction control means is provided for reducing the reference value by a predetermined amount when a failure occurs in the lock brake device. In the door.

[0005]

In the present invention constructed as described above, if the anti-lock brake device is normal, the comparing means compares the degree of sudden braking detected by the sudden braking detecting means with a predetermined reference value. According to the comparison result, the switching control means controls the suspension mechanism to set the suspension characteristics of the vehicle to the soft side when the detection degree is smaller than the reference value, and sets the suspension when the detection degree is larger than the reference value. Switch the characteristics to the hardware side. With this, if the degree of sudden braking is small, the anti-lock brake device avoids locking of each wheel to ensure the running stability of the vehicle, and at the same time, the suspension mechanism keeps the suspension characteristics soft and improves the riding comfort of the vehicle. Make it good. Also, if the degree of sudden braking of the vehicle is large, the anti-lock brake device avoids locking of each wheel to ensure the running stability of the vehicle,
The suspension mechanism switches the suspension characteristics to the hard side and suppresses the dive of the vehicle body, thereby ensuring the running stability of the vehicle during sudden braking. On the other hand, when a failure occurs in the antilock brake device, the decrease control means reduces the reference value by a predetermined amount. Therefore,
In the case where the running stability of the vehicle is not ensured by the anti-lock brake device at the time of sudden braking, even if the degree of sudden braking of the vehicle is smaller than the above case, the suspension characteristics of the vehicle are switched to the hard side. The characteristics can be easily switched to the hardware side. Thereby, in this case, the suspension mechanism suppresses the dive of the vehicle body at the time of sudden braking and keeps the running stability of the vehicle good.

[0006]

As can be understood from the above description of the operation,
According to the present invention, if the anti-lock brake device is normal, the running stability of the vehicle at the time of sudden braking is ensured, and the riding comfort of the vehicle is also kept good. Ride comfort can be achieved. Further, when a failure occurs in the anti-lock brake device or when the degree of sudden braking is large, the suspension mechanism can maintain good running stability of the vehicle during sudden braking.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 schematically shows a vehicle suspension device SU and an anti-lock brake device BR.

The suspension system SU includes shock absorbers 11a to 11d, main air chambers 12a to 12d, and auxiliary air chambers 13a to 13 provided between the respective wheels and the vehicle body corresponding to the left and right front wheels and rear wheels, respectively.
d. The shock absorbers 11a to 11d can change the damping force against the vertical movement of the vehicle body in three stages (small, medium, and large) according to the valve opening controlled by the actuators 14a to 14d. The main air chambers 12a to 12d are (main air chambers 12a to 1d).
When the 2d and the sub air chambers 13a to 13d communicate with each other, the sub air chambers 13a to 13d also), so that the vehicle height at each wheel position can be continuously changed in accordance with the amount of stored air. I have. Sub air chambers 13a to 13d
The two-stage (small, large) spring constants for the vertical movement of the vehicle body in cooperation with the main air chambers 12a to 12d by turning on / off a valve whose communication with the main air chambers 12a to 12d is switched by the actuators 15a to 15d.
It is changed to.

A supply / discharge device for supplying / discharging air to / from the main air chambers 12a to 12d is connected to the main air chambers 12a to 12d. This supply / discharge device includes a compressor 17 driven by an electric motor 16. The compressor 17 includes a check valve 18, an air dryer 19, a check valve 21 and an orifice 22 connected in parallel, and electromagnetic switching provided for each wheel. They are connected to the main air chambers 12a to 12d via valves 23a to 23d. These electromagnetic switching valves 23a to 23d are normally in an off state, and are turned on by energization to check valve 2
1 and orifice 22 and each air chamber 12a-12
Each communication with d is allowed. An electromagnetic switching valve 24 is connected to a connection point between the check valve 18 and the air dryer 19, and the valve 24 is normally in an off state, and is turned on by energization to communicate the connection point to the atmosphere.

Next, the aforementioned actuators 14a to 14a-1
4d, 15a to 15d and electromagnetic switching valves 23a to 2
An electric control device for controlling 3d and 24 will be described.
This electric control device includes stroke sensors 31a to 31
d, a mode switch 32, a brake switch 33, a vehicle speed sensor 34, and a microcomputer 35. The stroke sensors 31a to 31d are provided at respective wheel positions, and the displacement amounts (hereinafter, stroke amounts) S _FL , S _{F R} , and the downward displacement with respect to the reference height of the vehicle body at the same positions.
It detects S _RL and S _RR respectively and outputs these detection signals. The mode switch 32 is operated by the driver,
An operation switch for selectively switching a suspension characteristic between a normal mode and a sports mode. The brake switch 33 detects a depression operation of the brake pedal 41, and is normally in an off state and is turned on when the brake pedal 41 is depressed. The vehicle speed sensor 34 detects the vehicle speed V and outputs a detection signal indicating the same speed V. The microcomputer 35 includes a CPU, a ROM, a RAM, a timer, and the like. The microcomputer 35 repeatedly executes the "main program" shown in FIG. Interrupt the program.

The anti-lock brake device BR is provided with a brake hydraulic pressure control device 43 for supplying a brake hydraulic pressure fed from a pump 42 by a depression operation of a brake pedal 41 to a wheel cylinder (not shown) provided for each wheel. . An anti-lock electric control device 44 is connected to the brake hydraulic control device 43. The anti-lock control device 44 includes a sensor for detecting the rotation speed of each wheel, an estimation circuit for estimating the lock of each wheel from the rotation speed of each wheel detected by the sensor, and an anti-lock control device 44 for each wheel cylinder based on the estimation by the estimation circuit. A control circuit for forming a control signal indicating supply, stop, and release of the brake hydraulic pressure is provided. By outputting a control signal to the brake hydraulic control device 43, locking of each wheel during rapid braking of the vehicle is avoided. ing. The antilock electric control unit 44 detects a failure of various sensors, various circuits, and the like, and outputs a detection signal indicating a failure to the microcomputer 35 when the failure is detected.

Next, the operation of the embodiment configured as described above will be described with reference to the flowchart. When an ignition switch (not shown) is turned on, the microcomputer 35 starts execution of the "main program" in step 100 of FIG. 2, and in step 102, an anti-dive flag ADFL indicating that anti-dive control is performed.
Is initialized to "0", and the circulating process including steps 104 to 116 is repeatedly executed. In this circulating process, the anti-dive flag ADFL is initially "0", so the microcomputer 35 makes a "NO" determination in step 104, and switches the program to steps 106 and 10.
Proceed to 8. In step 106, the vehicle speed sensor 3
Vehicle by the compared with the vehicle speed V and the predetermined vehicle speeds V ₁ to detect the 3 determines whether a high speed running. In step 108, whether the normal mode or the sports mode is selected as the suspension characteristic is determined based on the setting of the mode switch 32.

If the vehicle is not running at high speed and the normal mode is selected, the microcomputer 35 determines "NO" in step 106 and determines "YES" in step 108, and executes the program in step 108. Proceed to 110. In step 110, the damping force of the shock absorbers 11a to 11d is set to "small" or soft by controlling the actuators 14a to 14d, and the main air chambers 12a to 12d are controlled by controlling the actuators 15a to 15d. The air chambers 13a to 13d are communicated with each other to
The spring constant by 2a-12d and 13a-13d is "small"
That is, it is set to software. If the vehicle is running at high speed or the sport mode is selected, the microcomputer 35 determines “YES” in step 106 or determines “NO” in step 108,
The program proceeds to step 112. Step 112
In the above, the damping force of the shock absorbers 11a to 11d is set to "medium" or middle by controlling the actuators 14a to 14d, and the main air chamber 1 is controlled by controlling the actuators 15a to 15d.
The communication between the sub-air chambers 13a to 13d and the sub-air chambers 13a to 13d is released to release both chambers 12a to 12d and 13a to 13d.
Is set to "large", that is, hard.

After the processing in steps 110 and 112, the microcomputer 35 determines in step 116 the stroke amounts S _FL , S _FR , S _RL and S S detected by the stroke sensors 31a to 31d and the vehicle speed sensor 34, respectively.
_RR , electromagnetic switching valve 23a-2 based on vehicle speed V, etc.
3d and 24 are controlled to adjust the vehicle height at each wheel position.

On the other hand, during the circulation processing consisting of steps 104 to 116, the microcomputer 35 interrupts and executes the "sudden braking detection program" of FIG. In this "sudden braking detection program", the microcomputer 35 starts its execution at step 200, and at step 202, the vehicle speed V and the stroke amount S _FL detected by the vehicle speed sensor 33 and the stroke sensors 31a, 31b, respectively. _SFR is read, and in step 204, the average stroke amount S = ( _SFL + _SFR ) / 2 at the left and right front wheel positions is calculated from the detected stroke amounts _SFL and _SFR . Next, the microcomputer 35 proceeds to step 20.
At 6, it is determined whether or not a signal indicating a failure of the antilock brake device BR is input from the antilock electric control device 44.

First, a case where no failure occurs in the antilock brake device BR will be described. In this case, since the signal indicating the failure of the anti-lock brake device BR is not input from the anti-lock electric control device 44, the microcomputer 35 determines “NO” in step 206, and in step 208, the reference vehicle speed Vre.
f, comparing the reference time Tref with first reference stroke volume Sref1 and second reference stroke Sref2 is set to the large predetermined vehicle speed V ₀ and a predetermined stroke relatively respectively _{S 1, S 2 (S 1} <S 2) It is set to a very small predetermined time T ₀ (for example, 1 second).

Next, the microcomputer 35 determines the necessity of anti-dive control according to the degree of sudden braking in steps 212 to 218. If the brake pedal 41 is not depressed, the brake switch 33 is not turned on.
Is determined to be "NO", and the program proceeds to step 224. Even if the brake pedal 41 is depressed,
When the vehicle speed V is equal to or higher than the reference vehicle speed Vref and the average stroke amount S of the vehicle body at the front wheel position is less than the first reference stroke amount Sref1, or when the vehicle speed V is less than the reference vehicle speed Vref and the average stroke amount S is the second Reference stroke amount Sref2
If it is less than the above, the microcomputer 35 advances the program to step 224 by the processing of steps 212 to 218. In step 224, it is determined whether or not the anti-dive flag ADFL is "1". If the flag ADFL is maintained at "0" as in the initial state, the microcomputer 35 determines "NO" in step 224, and in step 232 after the processing of step 230, the microcomputer 35 "Braking detection program" is ended. In this case, the anti-dive flag ADFL is still "
The damping force of the suspension device SU is set to "small" (soft) or "medium" (middle) in accordance with the selection mode (normal mode or sports mode) as described above. The spring constant of the device SU is set to “small” (soft) or “large” (hard).

When the brake pedal 41 is suddenly depressed and the vehicle speed V is equal to or higher than the reference vehicle speed Vref and the average stroke amount S of the vehicle body at the front wheel position is equal to the first reference stroke amount S
ref1 or more, or the vehicle speed V becomes the reference vehicle speed Vref
If the average stroke amount S is smaller than the second reference stroke amount Sref2, the microcomputer 35 advances the program to steps 220 and 222 by the processing of steps 212 to 218. Step 220
In, change the anti-dive flag ADFL to "1",
In step 222, the anti-dive timer value ADTM is initialized to "0". After these processes, the microcomputer 35 goes through step 230 to step 2
At 32, the execution of the "sudden braking detection program" is terminated.

Thus, the anti-dive flag ADFL is set to "
If “1” is set, the microcomputer 35 determines “YES” in step 104 of the “main program”, and advances the program to step 114. In step 114, the shock absorbers 11a to 11d are controlled by controlling the actuators 14a to 14d.
The communication between the main air chambers 12a to 12d and the sub air chambers 13a to 13d is released by setting the damping force to "large" (hard) and controlling the actuators 15a to 15d so that both chambers 12a to 12d, 13a-1
The spring constant according to 3d is set to “large” (hard). Accordingly, when the front portion of the vehicle body dives by a predetermined amount by a sudden depression operation of the brake pedal 41, the damping force and the spring constant of the suspension device SU become "large" (hard).
And dive of the vehicle body is suppressed.

In this state, when the depression operation of the brake pedal 41 is released or the dive amount at the front of the vehicle body decreases (when the vehicle speed V is equal to or higher than the reference vehicle speed Vref, the average stroke amount S of the vehicle body at the front wheel position is reduced. When the vehicle speed V is less than the reference vehicle speed Vref, the stroke amount S becomes less than the second reference stroke amount Sref2 when the vehicle speed V is less than the first reference stroke amount Sref1), and the microcomputer 35 executes the program in steps 212 to 218. Proceed to step 224. In this case, the anti-dive flag AD
Since FL is set to “1”, the microcomputer 35 determines “YES” in step 224, and in step 226, sets the anti-dive timer value ADTM to the reference time T.
It is determined whether the value is equal to or greater than the value corresponding to ref. The anti-dive timer value ADTM is initially set to “0” in step 222, and “1” in step 230.
The count is incremented by one, and is kept at a small value when the state has changed shortly. Therefore, in this case, the microcomputer 35 determines “NO” in step 226 and ends the execution of the “sudden braking detection program” in step 232 through the processing in step 230. Thereby, the brake pedal 4
After the depressing operation of No. 1 is released or the diving amount at the front part of the vehicle body is reduced, the damping force and the spring constant of the suspension device SU are set to "large" (hard) until the reference time Tref elapses. .

On the other hand, when the reference time Tref elapses after the depression operation of the brake pedal 41 is released or the dive amount at the front of the vehicle body decreases, the anti-dive timer value ADTM becomes equal to or more than the value corresponding to the reference time Tref. So
The microcomputer 35 determines in step 226 that “YE
S ”and the anti-dive flag is set in step 228.
Change ADFL to “0”. Accordingly, the microcomputer 35 determines “NO” in step 104 of the “main program” and advances the program to step 106 and subsequent steps. As described above, according to the selection mode (normal mode or sports mode), the suspension device The damping force of the SU is set to "small" (soft) or "medium" (middle), and the spring constant of the SU is set to "small" (soft) or "large" (hard). .

On the other hand, at the time of such a rapid braking, the antilock electric control unit 44 controls the brake hydraulic control unit 43 so that each wheel is not locked by the rotation speed of each wheel. Therefore, even when the vehicle is suddenly braked, the wheels are not locked, and the running stability of the vehicle is ensured up to a certain amount of sudden braking. On the other hand, in the suspension device SU, the reference vehicle speed Vref, the first and second reference stroke amounts Sref1, Sr are obtained by the processing in step 208.
Since ef2 is set to a relatively large value and the reference time Tref is set to be relatively short, both the damping force and the spring constant of the suspension device SU are hard to be set to "large", and the ride comfort of the vehicle is good. Will be kept. Note that the degree of sudden braking is extremely large, and the vehicle speed V is equal to the reference vehicle speed Vre.
f and the average stroke amount S is equal to or greater than the first reference stroke amount Sref1, or the vehicle speed V is less than the reference vehicle speed Vref and the average stroke amount S is equal to the second reference stroke amount Sre.
If f2 or more, the damping force and the spring constant are set to "large", so that the suspension device SU suppresses the dive of the vehicle body and maintains the running stability of the vehicle together with the anti-lock brake device BR in a favorable state.

Next, a case where a failure occurs in the antilock brake device BR will be described. In this case, the anti-lock electric control unit 44 releases the anti-lock control of each wheel and outputs a signal indicating a failure to the microcomputer 35. Accordingly, the microcomputer 35 determines “YE” in step 206 of FIG.
S ”, the program proceeds to step 210. In step 210, the reference vehicle speed Vref, the first
Reference stroke amount Sref1 and second reference stroke amount S
ref2 is the predetermined speed V ₀ and the predetermined stroke amounts S ₁ , S ₂
A predetermined vehicle speed V ₀ smaller by predetermined smaller amounts ΔV and ΔS.
−ΔV and the predetermined stroke amounts S ₁ −ΔS, S ₂ −ΔS, respectively, and the reference time Tref is set to a time T ₀ + ΔT longer than the predetermined time T ₀ by a predetermined amount ΔT. Next, the microcomputer 35 executes the same processing of steps 212 to 232 as described above.

Therefore, the antilock brake device B
When the vehicle is suddenly braked in a state where a failure has occurred in R, both the damping force and the spring constant of the suspension device SU are likely to be set to “large”, and the damping force and the spring constant are set to “large”. The set time also becomes longer. As a result, the tendency of the suspension device SU to suppress the dive of the vehicle body increases, so that even if the running stability of the vehicle at the time of sudden braking is not ensured by the anti-lock brake device BR, the vehicle of the vehicle at the time of sudden braking is secured by the suspension device SU. The running stability is well maintained.

In the above-described embodiment, the rapid braking of the vehicle is detected based on the average stroke amount S (dive amount) of the vehicle body at the front wheel position. However, the depressing speed and the depressing amount of the brake pedal 41 are not less than a predetermined amount. , Or when the fall (change rate) of the brake hydraulic pressure becomes abrupt (a predetermined value or more), sudden braking of the vehicle may be detected. Alternatively, sudden braking of the vehicle may be detected by measuring the deceleration of the vehicle.

[Brief description of the drawings]

FIG. 1 is a schematic view of a suspension device and an anti-lock brake device showing one embodiment of the present invention.

FIG. 2 is a flowchart corresponding to a “main program” executed by the microcomputer of FIG. 1;

FIG. 3 is a flowchart corresponding to a “sudden braking detection program” executed by the computer.

[Explanation of symbols]

SU: suspension device, BR: anti-lock brake device, 11a to 11d: shock absorber, 12a
-12d: Main air chamber, 13a-13d: Sub air chamber, 14a-14d, 15a-15d: Actuator, 17: Compressor, 23a-23d, 24: Electromagnetic switching valve, 31a-31d: Stroke sensor, 3
3 Brake switch, 34 Vehicle speed sensor, 35 Microcomputer, 41 Brake pedal, 43 Brake hydraulic control device, 44 Anti-lock electric control device.

Claims (1)

(57) [Claims] 1. A suspension mechanism applied to a vehicle equipped with an anti-lock brake device and capable of changing suspension characteristics of the vehicle, rapid braking detection means for detecting a degree of rapid braking of the vehicle, Comparing means for comparing with a predetermined reference value, controlling the suspension mechanism in accordance with the comparison result of the comparing means, and setting the suspension characteristic to a soft side when the detection degree is smaller than the reference value; Switching control means for switching the suspension characteristics to the hard side when the value is larger than the reference value, wherein the reference value is reduced by a predetermined amount when a failure occurs in the antilock brake device. A suspension characteristic control device for a vehicle, comprising a reduction control means.