JPH06106942A - Vehicle suspension characteristic control device - Google Patents

Abstract

(57) [Abstract] [Purpose] In a vehicle provided with an anti-lock brake device BR and a suspension device SU capable of switching between soft and hard, the driving stability is given the highest priority and the riding comfort of the vehicle is made as good as possible. When the anti-lock brake device BR is normal and the device BR secures the running stability of the vehicle by avoiding wheel locking during sudden braking of the vehicle, a computer in the suspension device SU is provided. 35
Keeps the suspension characteristics as soft as possible even during sudden braking of the vehicle. As a result, both traveling stability and riding comfort of the vehicle are achieved. When a failure occurs in the anti-lock brake device BR and the traveling stability of the vehicle at the time of sudden braking is not ensured by the device BR, the computer 35 makes it easy to switch the suspension characteristic to hard at the time of sudden braking of the vehicle, The vehicle dive is suppressed to ensure the running stability of the vehicle.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a suspension characteristic control device for a vehicle in which a suspension characteristic is set to a hard side when the vehicle is suddenly braked so as to suppress a dive of a vehicle body.

[0002]

2. Description of the Related Art Conventionally, a vehicle of this type is disclosed in, for example, Japanese Patent Laid-Open No.
As disclosed in Japanese Patent Publication No. 3-34213, an anti-lock brake device for avoiding locking of wheels during 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 characteristic 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 during sudden braking is improved.

[0003]

Generally, when the suspension characteristic of the vehicle is switched to the hard side, the posture change of the vehicle body is suppressed and the running stability of the vehicle is improved, but the riding comfort of the vehicle is improved. Tends to disappear. Therefore, in the above-mentioned conventional device, even if 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 characteristic of the vehicle is switched to the hard side. The running stability of the vehicle becomes better than necessary, but there is a problem that the riding comfort of the vehicle deteriorates. The present invention has been made in consideration of the above-mentioned problems comprehensively, and an object thereof is to place a top priority on the running stability of a vehicle by controlling the suspension characteristics of the vehicle according to the state of the anti-lock brake device. 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 made as good as possible.

[0004]

In order to achieve the above object, the structural feature of the present invention is applied to a vehicle equipped with an antilock brake device, and a suspension mechanism capable of changing the suspension characteristics of the vehicle, Sudden braking detection means for detecting the degree of sudden braking of the vehicle, comparison means for comparing the detected degree with a predetermined reference value, and the suspension mechanism is controlled according to the comparison result of the comparison means to detect the degree of detection. A suspension characteristic control device for a vehicle, comprising: a switching control unit that sets the suspension characteristic to a soft side when it is smaller than the reference value and switches the suspension characteristic to a hard side when the detection degree is larger than the reference value. 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 antilock 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, and According to the comparison result, the switching control means controls the suspension mechanism to set the suspension characteristic of the vehicle to the soft side when the detection degree is smaller than the reference value, and when the detection degree is larger than the reference value, the suspension mechanism. Switch the characteristics to the hardware side. As a result, if the degree of sudden braking is small, the anti-lock braking device avoids locking of each wheel to ensure vehicle running stability, while the suspension mechanism keeps the suspension characteristics soft to provide a comfortable ride. To be good. Also, if the degree of sudden braking of the vehicle is large, the anti-lock braking device avoids locking of each wheel to ensure traveling stability of the vehicle, and at the same time,
The suspension mechanism switches the suspension characteristics to the hard side to suppress 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 decreases the reference value by a predetermined amount. Therefore,
When the anti-lock braking system does not ensure the running stability of the vehicle during sudden braking, the suspension characteristics of the vehicle are switched to the hard side even if the degree of sudden braking of the vehicle is smaller than the above case, that is, the suspension of the vehicle. The characteristics are easily switched to the hardware side. As a result, in this case, the suspension mechanism suppresses the dive of the vehicle body at the time of sudden braking, and maintains good traveling stability of the vehicle.

[0006]

As can be understood from the above description of the operation,
According to the present invention, when the anti-lock brake device is normal, the traveling stability of the vehicle during sudden braking is ensured and the riding comfort of the vehicle is also kept good. Both ride comfort can be achieved. Further, when a failure occurs in the antilock 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 antilock brake device BR.

The suspension unit SU includes shock absorbers 11a to 11d, main air chambers 12a to 12d, and sub air chambers 13a to 13 provided between the left and right wheels respectively corresponding to the front and rear wheels.
have d. The shock absorbers 11a to 11d can change the damping force with respect to the vertical movement of the vehicle body in three stages (small, medium, and large) according to the valve opening degrees controlled by the actuators 14a to 14d. The main air chambers 12a-12d are (main air chambers 12a-1
2d and the sub air chambers 13a to 13d are in communication with each other, the sub air chambers 13a to 13d) can continuously change the vehicle height at each wheel position in accordance with the amount of stored air. There is. Sub air chambers 13a to 13d
Is a two-step spring constant for the vertical movement of the vehicle body (small, large) in cooperation with the main air chambers 12a-12d by turning on / off a valve whose communication with the main air chambers 12a-12d is switched by the actuators 15a-15d.
To change 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. The 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. It is connected to the main air chambers 12a to 12d via the valves 23a to 23d. These electromagnetic switching valves 23a to 23d are normally in the off state, and are turned on by energization to turn on the check valve 2.
1 and orifice 22 and each air chamber 12a-12
Allow each communication with d. Further, 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 energizing to make the connection point communicate with the atmosphere.

Next, the above-mentioned actuators 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. Stroke sensor 31a~31d are respectively provided in each wheel position, displacement amount of downward relative to the reference height of the vehicle body at the same position (hereinafter, stroke) S _FL, S _{F R,}
Each of S _RL and S _RR is detected and these detection signals are output. The mode switch 32 is operated by the driver,
This is an operation switch that selectively switches the suspension characteristics between normal mode and sports mode. The brake switch 33 detects the depression operation of the brake pedal 41, and is normally off 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 is composed of a CPU, a ROM, a RAM, a timer, etc., and 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 the brake hydraulic pressure pumped from the pump 42 by depressing the brake pedal 41 to a wheel cylinder (not shown) provided for each wheel. . An antilock electric control device 44 is connected to the brake hydraulic pressure control device 43. The anti-lock control device 44 includes a sensor that detects the rotation speed of each wheel, an estimation circuit that estimates the lock of each wheel from the rotation speed of each wheel detected by the sensor, and a wheel cylinder based on the estimation performed by the estimation circuit. A control circuit that forms a control signal indicating supply, stop, and release of the brake hydraulic pressure is provided, and by outputting the control signal to the brake hydraulic pressure control device 43, it is possible to avoid the lock of each wheel during the sudden braking of the vehicle. ing. Further, the anti-lock electric control device 44 detects a failure of various sensors and various circuits and outputs a detection signal indicating the 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 above flow chart. When the ignition switch (not shown) is turned on, the microcomputer 35 starts the execution of the "main program" in step 100 of FIG. 2 and the anti-dive flag ADFL indicating that the anti-dive control is performed in step 102.
After being initialized to "0", the cyclic processing including steps 104 to 116 is repeatedly executed. In this circulation processing, since the anti-dive flag ADFL is initially "0", the microcomputer 35 makes a "NO" determination at step 104 to execute the program at steps 106 and 10.
Proceed to 8. In step 106, the vehicle speed sensor 3
By comparing the vehicle speed V detected in 3 with the predetermined vehicle speed V ₁ , it is determined whether or not the vehicle is traveling at high speed. Further, in step 108, it is determined whether the normal mode or the sports mode is selected as the suspension characteristic depending on the setting state of the mode switch 32.

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

After the processing in steps 110 and 112, the microcomputer 35 in step 116 detects the stroke amounts S _FL , S _FR , S _RL and S detected by the stroke sensors 31a to 31d and the vehicle speed sensor 34, respectively.
Solenoid switching valves 23a-2a based on _RR , vehicle speed V, etc.
The vehicle height at each wheel position is adjusted by controlling 3d and 24.

On the other hand, during the circulation processing consisting of the steps 104 to 116, the microcomputer 35 interrupts and executes the "quick braking detection program" of FIG. 3 every predetermined time. In this "rapid 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 , respectively detected by the vehicle speed sensor 33 and the stroke sensors 31a and 31b. _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, the 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 antilock brake device BR is not input from the antilock electric control device 44, the microcomputer 35 determines “NO” in step 206, and determines the reference vehicle speed Vre in step 208.
f, the first reference stroke amount Sref1 and the second reference stroke amount Sref2 are respectively set to relatively large predetermined vehicle speed V ₀ and predetermined stroke amounts S ₁ , S ₂ (S ₁ <S ₂ ), and the reference times Tref are compared. It is set to a predetermined small time T ₀ (for example, 1 second).

Next, the microcomputer 35 determines in steps 212 to 218 whether or not the anti-dive control is required according to the degree of the sudden braking. If the brake pedal 41 is not depressed, the brake switch 33 does not turn on.
Is determined as "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 less, the microcomputer 35 advances the program to step 224 by the processing of steps 212 to 218. In step 224, it is determined whether the anti-dive flag ADFL is "1". If the flag ADFL is maintained at "0" as in the initial state, the microcomputer 35 makes a "NO" determination at step 224, and at step 232 after the processing at step 230, this "quick" is set. The "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) according to 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).

The brake pedal 41 is suddenly depressed, 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 the first reference stroke amount S.
If ref1 or more, or the vehicle speed V is the reference vehicle speed Vref
When the average stroke amount S is less than the above and the average stroke amount S is equal to or more 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 the process of step 230 and then to step 2
At 32, the execution of this "rapid braking detection program" is terminated.

In this way, the anti-dive flag ADFL is "
If set to "1", 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.
Is set to "large" (hard), and the actuators 15a to 15d are controlled to release the communication between the main air chambers 12a to 12d and the sub air chambers 13a to 13d, so that both chambers 12a to 12d, 13a-1
Set the spring constant according to 3d to "large" (hard). Therefore, when the front part 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 are “large” (hard).
Is set to suppress the dive of the vehicle body.

From this state, when the depression operation of the brake pedal 41 is released or the dive amount at the front portion of the vehicle body becomes small (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 When the vehicle speed V is less than the reference vehicle speed Vref when the first reference stroke amount Sref1 is less than the second reference stroke amount Sref2), the microcomputer 35 executes the program by the processing of 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 the anti-dive timer value ADTM is set to the reference time T in step 226.
Determines whether it is greater than or equal to the value corresponding to ref. The anti-dive timer value ADTM is initialized to "0" in step 222 and "1" in step 230.
It is incremented by one, and is kept at a small value shortly after the change in the state. Therefore, in this case, the microcomputer 35 determines "NO" in step 226, completes the process of step 230, and ends the execution of this "rapid braking detection program" in step 232. As a result, the brake pedal 4
The damping force and spring constant of the suspension device SU continue to be set to "large" (hard) until the reference time Tref elapses after the depression operation of 1 is released or the dive amount at the front part of the vehicle body becomes small. .

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 part of the vehicle body becomes small, the anti-dive timer value ADTM becomes equal to or more than the value corresponding to the reference time Tref. So
In step 226, the microcomputer 35 returns "YE
S "is determined and the anti-dive flag is determined in step 228.
Change ADFL to "0". Therefore, the microcomputer 35 determines "NO" in step 104 of the "main program" and advances the program to step 106 and subsequent steps, so that the suspension device is selected according to the selection mode (normal mode or sports mode) as described above. The damping force of the SU is set to "small" (soft) or "medium" (middle), and the spring constant of the device SU is set to "small" (soft) or "large" (hard). .

On the other hand, during such sudden braking, the anti-lock electric control device 44 controls the brake hydraulic pressure control device 43 so that the wheels do not lock due to the rotational speed of the wheels. Therefore, even if the vehicle is suddenly braked, the wheels are not locked, and the running stability of the vehicle is secured until the vehicle is suddenly braked to some extent. On the other hand, in the suspension device SU, the reference vehicle speed Vref, the first and second reference stroke amounts Sref1, Sr are processed by the processing of step 208.
Since ef2 is set to a relatively large value and the reference time Tref is set to a relatively short value, it is difficult to set both the damping force and the spring constant of the suspension device SU to "large", and the riding comfort of the vehicle is improved. To be kept. The degree of sudden braking is extremely large, and the vehicle speed V is equal to the reference vehicle speed Vre.
If f or more and the average stroke amount S is the first reference stroke amount Sref1 or more, or if the vehicle speed V is less than the reference vehicle speed Vref and the average stroke amount S is the second reference stroke amount Sre.
If it is 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 good running stability of the vehicle together with the antilock brake device BR.

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 fail to the microcomputer 35. Therefore, the microcomputer 35 returns "YE" in step 206 of FIG.
S ”, and 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 that is} smaller by a predetermined smaller amount ΔV, ΔS
−ΔV and 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 processing of steps 212 to 232 similar to the above.

Therefore, the anti-lock brake device B
When the vehicle is suddenly braked in the state where the failure occurs in R, both the damping force and the spring constant of the suspension device SU are easily 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 suspension device SU is more likely to suppress the dive of the vehicle body. Therefore, even if the anti-lock brake device BR does not ensure the running stability of the vehicle during the sudden braking, the suspension device SU can prevent the vehicle from dive during the sudden braking. The running stability is kept good.

In the above embodiment, the sudden braking of the vehicle is detected by the average stroke amount S (dive amount) of the vehicle body at the front wheel position. However, the depression speed and the depression amount of the brake pedal 41 are equal to or more than a predetermined amount. The sudden braking of the vehicle may be detected when the brake hydraulic pressure falls (rate of change) becomes sudden (above a predetermined value). Alternatively, the deceleration of the vehicle may be measured to detect sudden braking of the vehicle.

[Brief description of drawings]

FIG. 1 is a schematic view of a suspension device and an antilock brake device showing an embodiment of the present invention.

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

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

[Explanation of symbols]

SU ... Suspension device, BR ... Antilock brake device, 11a-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 ... Antilock electric control device.

Claims (1)

[Claims] 1. A suspension mechanism which is applied to a vehicle equipped with an anti-lock brake device and which can change the suspension characteristics of the vehicle, a sudden braking detecting means for detecting the degree of sudden braking of the vehicle, and the detected degree. Comparing means for comparing with a predetermined reference value, and controlling the suspension mechanism according to the comparison result of the comparing means to set the suspension characteristic to the soft side when the detection degree is smaller than the reference value and to set the same detection degree. In a suspension characteristic control device for a vehicle, which switches the suspension characteristic to the hard side when is larger than the reference value, the reference value is reduced by a predetermined amount when the antilock brake device fails. A suspension characteristic control device for a vehicle, characterized in that reduction control means is provided.