JPH0585329A - Vehicle slip control device - Google Patents

Abstract

(57) [Abstract] [Purpose] In contrast to the slip control device in which the threshold value for slip control is changed according to the steering angle of the vehicle detected by the encoder-type steering angle sensor 114, the steering angle sensor 1
The vehicle running stability is ensured by slip control when a frame skipping abnormality occurs in the output signal of 14. [Structure] An output abnormality of the steering angle sensor 114 is detected by a detecting means 13.
1 and when there is an abnormality, the correction unit 132 corrects the signal input from the steering angle sensor 114 to the control unit to a signal in the direction in which the steering angle increases.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle slip control device.

[0002]

2. Description of the Related Art Conventionally, for example, an anti-skid brake device and a traction control device have been known as this type of vehicle slip control device. The anti-skid brake device controls the brake hydraulic pressure of the vehicle to adjust the braking force of each wheel to prevent the wheel from being locked or skid during braking. On the other hand, the traction control device detects the slip amount of the drive wheels in order to prevent the drive wheels from slipping due to excessive drive torque and causing a drive loss when the vehicle accelerates, and the acceleration performance is reduced. The brake fluid pressure applied to the drive wheels and the engine output are controlled so that the slip amount of the drive wheels becomes the target slip amount corresponding to the friction coefficient of the road surface (the braking force is applied to the drive wheels or the engine output is reduced. To let).

As an example of such a slip control device, Japanese Patent Laid-Open No. 60-1061 discloses a conventional anti-skid brake device which detects a steering angle of front wheels (steering wheels) and detects the steering angle according to the steering angle. It has been proposed to change the threshold value of skid brake control to control the braking hydraulic pressure of the steered wheels during straight-ahead braking to a high level to shorten the braking distance.

[0004]

An encoder type steering angle sensor is used as a steering angle detecting means for detecting the steering angle of the front wheels (steering wheels). This rudder angle sensor is provided with, for example, a disc that is rotatably and integrally attached to a steering shaft, and a large number of slits are arranged in two rows in the radial direction in the circumferential direction of the disc. They are arranged in a staggered manner. LEDs (light emitting diodes) that project light toward each slit on one side of the disk
And a light receiving means such as a phototransistor for allowing light from the light emitting means that has passed through the slit to be incident on the other side, one pair corresponding to each slit row, and integrated with the steering shaft. The steering direction and the steering angle are determined based on the light receiving pattern and the number of times of light reception to the light receiving means due to the rotation of the disk.

However, in the encoder type steering angle sensor, an abnormal state called frame skipping may occur, and at that time, there is a possibility that the proper normal slip control cannot be performed. That is, the output signal level of the light receiving means when the light from the light emitting means passes through the slit and is input to the light receiving means is set to "1", and the light is interfered by the disc between the slits and is not input to the light receiving means. When set to "0", the output signals of both light receiving means are (0,0), (0,1), (1,0), (1, due to the phase difference between the inner and outer slit rows.
The state of 1) is reached and these combinations are repeated. In principle, for example, the combination of signals output next to (0,0) is (0,1) or (1,0), which cannot be in the (1,1) state. When an abnormality occurs, (0,
0) immediately shifts to (1, 1), and an abnormal signal condition occurs.

The present invention has been made in view of the above points, and an object thereof is to correct a signal from the steering angle sensor to a predetermined state when an abnormality of the steering angle sensor occurs. It is to ensure the running stability of the vehicle by slip control.

[0007]

In order to achieve the above object, in the invention of claim 1, when the steering angle sensor is abnormal, the signal from the steering angle sensor is corrected so that the steering angle increases. ..

That is, according to the present invention, as shown in FIG. 1, an encoder type steering angle sensor 114 for detecting the steering angle of the steered wheels 7FL, 7FR and a slip according to the steering angle detected by the steering angle sensor 114 are used. In the slip control device including a control unit 111 that controls the control threshold of the control amount to change, an abnormality detection unit 131 that detects that an output signal of the steering angle sensor 114 has an abnormality.
When the abnormality detection unit 131 detects an abnormality in the output signal of the steering angle sensor 114, a correction unit that corrects the signal input from the steering angle sensor 114 to the control unit 111 to a signal in the direction of increasing the steering angle. And 132 are provided.

[0009]

With the above-described structure, in the present invention, the abnormality detection means 1 is that an abnormality has occurred in the output signal of the steering angle sensor 114.
When detected by 31, the correction unit 132 receiving the output of the detection unit 131 corrects the signal input from the steering angle sensor 114 to the control unit 111 to a signal in the direction of increasing the steering angle. By the correction to the signal in the direction in which the steering angle increases, for example, in the traction control, control in the direction in which the spin of the vehicle is suppressed is performed, so that the running stability of the vehicle is enhanced, and accordingly, the abnormality of the steering angle sensor 114 becomes The running stability of the vehicle can be secured even at times.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described below with reference to FIGS. In the vehicle shown in FIG. 5, 1 is an engine and 3 is an automatic transmission connected to the engine 1 via a torque converter 2. 7FL and 7FR are left and right front wheels, and 7RL and 7RR are left and right rear wheels. In this vehicle, the left and right rear wheels 7RL and 7RR are the engine 1, the automatic transmission 3, the propeller shaft 4, the differential device 5, and the left and right axles. Drive wheels are driven via 6L and 6R, and left and right front wheels 7FL and 7FR are driven wheels and steered wheels.

The automatic transmission 3 is a multi-speed transmission gear mechanism 3a.
Is equipped with. The speed change gear mechanism 3a is of a hydraulically actuated type as is known, and for example, in the embodiment, it is for four forward gears and one reverse gear. That is, shifting is performed by changing the combination of excitation and demagnetization of the plurality of solenoids 39a, 39a, ... Incorporated in the hydraulic circuit. Further, the torque converter 2 has a hydraulically operated lockup clutch 2a, and by switching between excitation and demagnetization of a solenoid 39b incorporated in the hydraulic circuit,
Signing and unbinding is performed.

The solenoids 39a and 39b are controlled by an AT controller 101 for controlling the shift of the automatic transmission 3. The AT controller 101 stores the shift characteristic and the lockup characteristic in advance, and performs the shift control and the lockup control based on this. Therefore, A
The T controller 101 includes throttle opening signals from a main throttle opening sensor 102 for detecting the opening of the main throttle valve 10 in the intake passage 8 and a sub throttle opening sensor 103 for detecting the opening of the sub throttle valve 12. And a vehicle speed signal (a rotation speed signal of the propeller shaft 4 in the embodiment) from the vehicle speed sensor 104 for detecting the vehicle speed.

The wheels 7FL to 7RR are respectively provided with brakes 21FL to 21RR. Calipers 22FL to 22RR of the brakes 21FL to 21RR
Brake piping 23F for each (wheel cylinder)
Brake fluid pressure is supplied via L-23RR.
The structure for supplying the brake fluid pressure is as follows. First, the depression force of the brake pedal 25 is boosted by a hydraulic booster 26 and transmitted to a tandem master cylinder 27. The master cylinder 2
Brake pipe 23 for the left front wheel is provided at the first outlet 27a of No. 7
The FL is connected to the second outlet 27b, and the brake pipe 23FR for the right front wheel is connected to the second outlet 27b.

The brake pipe 23FL for the left front wheel and the brake pipe 23FR for the right front wheel are provided with electromagnetic on-off valves 40A and 41A, respectively, and a relief connected downstream of the on-off valves 40A and 41A. Passage 42
Electromagnetic on-off valves 40B and 41B are provided on L and 42R, respectively.
Is installed.

The booster 26 is supplied with a hydraulic pressure from a pump 29 via a pipe 28, and the excess hydraulic pressure is returned to a reservoir tank 31 via a return pipe 30. A branch pipe 28a branched from the pipe 28 is connected to the merging portion a, and an electromagnetic opening / closing valve 32 is provided in the branch pipe 28a. The booster hydraulic pressure generated by the booster 26 is supplied to the merging portion a through a pipe 33, and the pipe 33 also has an electromagnetic opening / closing valve 34.
Is installed. A one-way valve 35 that allows only the flow toward the merging portion a is provided in the pipe 33 in parallel with the opening / closing valve 34.

Brake pipes 23RL and 23RR for the left and right rear wheels are connected to the confluence portion a. This piping 23
RL and 23RR are electromagnetic on-off valves 36A and 3R, respectively.
7A is interposed and the on-off valves 36A, 37
Electromagnetic on-off valves 36B and 37B are connected to the relief passages 38L and 38R connected downstream of A, respectively.

Each of the on-off valves 32, 34, 36A, 36
B, 37A, 37B, 40A, 40B, 41A, 41B
Are controlled by the controller 111. This controller 111 has a built-in microcomputer and is for performing anti-skid brake control and traction control. It should be noted that the controller 111 is not shown separately for anti-skid brake control and traction control, but the control content is different for each.

In this case, when the traction control (brake control) is not performed, the open / close valve 32 is closed, the open / close valve 34 is opened, the open / close valves 36B and 37B are closed, and the open / close valves 36A and 37A are opened as shown in the figure. Be done. This allows
When the brake pedal 25 is depressed, brake fluid pressure is supplied to the front wheel brakes 21FL and 21FR via the master cylinder 27. Further, to the rear wheel brakes 21RL and 21RR, a boosting hydraulic pressure corresponding to the stepping force of the brake pedal 25 from the hydraulic boosting device 26 is supplied as a brake hydraulic pressure via a pipe 33.

As will be described later, the opening / closing valve 34 is closed and the opening / closing valve 32 is opened when performing traction control. Further, the on-off valves 36A, 36B, 37A, 37
B, 40A, 41A, 40B and 41B are controlled to be opened and closed by duty control. In addition, the branch pipe 28
The brake fluid pressure that has passed through a does not act as a reaction force to the brake pedal 25 due to the action of the one-way valve 35.

In the case of traction control, drive wheels 7RL,
In order to reduce the drive torque of 7RR, drive wheels 7RL,
Brake control for 7RR and drive wheel 7
The driving force transmitted to the RL and 7RR, that is, the torque generated by the engine 1 is also reduced. Therefore, in the intake passage 8 of the engine 1, the main throttle valve 10 connected to the accelerator pedal 9 and the sub-throttle valve 12 connected to the throttle opening adjustment actuator 11 are arranged. The valve 12 is controlled by the controller 111 for controlling the traction via the actuator 11.

Next, the anti-skid brake control and traction control will be described in detail. First, the anti-skid brake control will be described. In this embodiment, the left front wheel 7FL is operated by operating the opening / closing valves 40A and 40B.
The first channel for adjusting the braking pressure of the brake 21FL and the operation of the opening / closing valves 41A and 41B cause the right front wheel 7FR to operate.
Brake 21FR of the right and left rear wheels 7RL, 7RR of the second channel for adjusting the braking pressure and the operation of the on-off valves 36A, 36B, 37A, 37B.
A third channel for adjusting the braking pressure of 1RR is provided, and these channels are controlled independently of each other.

The controller 111 for controlling the first to third channels detects the brake signal from the brake sensor 115 for detecting whether or not the brake pedal 25 is stepped on and the rotation speed of each wheel 7FL to 7RR. The wheel speed signals from the wheel speed sensors 112FL to 112RR and the turning angle signal from the steering angle sensor 114 are input,
Anti-skid brake control is performed in parallel for each channel.

The details of the control will be described in detail. The controller 111 includes a pseudo vehicle body speed setting unit and a control threshold value setting unit, and compares the control threshold value with the wheel acceleration / deceleration and the slip ratio to perform phase 0 (anti-skid brake). Non-controlled state), Phase I (state of braking pressure reduction during anti-skid brake control), Phase II (state of holding after decompression), Phase III (state of rapid pressure increase after pressure reduction hold) and Phase IV (state of rapid pressure increase after rapid pressure increase) A phase is selected from (slow pressure increase state), and a braking pressure control signal corresponding to each phase is output to the opening / closing valves 36A, 36B, 37A, 37B, 40A, 40.
B, 41A and 41B are output.

The pseudo vehicle speed Vr is set as a convenient vehicle speed based on the wheel speed, and the highest wheel speed of the four wheels 7FL to 7RR is set as the pseudo vehicle speed Vr. On the other hand, the amount of speed change depends on the friction coefficient of the road surface, from 1.2 G · Δt at high friction coefficient to 0 at low friction coefficient.
It is set up to 3 G · Δt and corrected as follows.
In addition, Δt is a sampling cycle (for example, 7 ms).

Vr ← Vr− (1.2 G · Δt to 0.3 G · Δt) The control threshold is set independently for each channel, and in the case of the present embodiment, the control threshold is the phase 0 described above. The first wheel deceleration threshold G1 for determining the transition from (when the anti-skid brake is not controlled) to Phase I (pressure reduction)
And the second wheel deceleration threshold G2 for determining the transition from phase I to phase II (hold), and phase II to phase II
First slip ratio threshold S1 for determining transition to I (rapid pressure increase)
And the wheel acceleration threshold value G3 for determining the transition from phase III to phase IV (slow pressure increase), and phase IV to phase I
There is a second slip ratio threshold S2 for determining the shift to. The control threshold is appropriately set according to the pseudo vehicle body speed Vr and the friction coefficient of the road surface.

Regarding the wheel speeds of the rear wheels 7RL and 7RR,
The smaller wheel speed of the two wheel speeds is selected as the rear wheel speed. Further, the slip ratio is calculated according to the following equation.

Slip rate = (1−wheel speed ÷ pseudo vehicle speed) × 100 As shown in FIG. 6, the setting of the control threshold value is performed on the road surface without excessively lowering the lateral drag coefficient μL of the wheel with respect to the road surface. It is set so that the friction coefficient μ with the wheel can be increased, that is, a characteristic in the range of Ss can be obtained.

The deceleration and acceleration of the wheel are obtained by dividing the difference between the previous value and the current value of the wheel speed by the sampling cycle Δt and converting the result into the gravitational acceleration. Therefore, normally, the increase / decrease control of the braking pressure as shown in FIG. 7 is performed. That is, when the brake pedal 25 is depressed from the constant speed running state, the braking pressure increases and the wheel speed decreases accordingly.

When the wheel deceleration becomes larger than the first wheel deceleration threshold G1, the control shifts to the anti-skid brake control, the phase I is selected, and the braking pressure is reduced according to a predetermined pressure reducing mode.

When the wheel deceleration becomes smaller than the second wheel deceleration threshold G2, the phase II is selected and the braking pressure is maintained in the reduced pressure state.

When the slip ratio decreases as the pressure is maintained and exceeds the first slip ratio threshold S1, phase III
Is selected, and the braking pressure is rapidly increased.

When the wheel acceleration decreases due to the sudden pressure increase and becomes equal to or less than the wheel acceleration threshold G3, the phase IV is selected and the braking pressure is gradually increased.

Due to the above-mentioned gentle pressure increase, the slip ratio becomes the second value.
Phase I is selected when the slip ratio threshold S2 is exceeded.

As described above, the braking pressures of the first to third channels are controlled to increase and decrease independently of each other to prevent the wheels from locking or skiding and to improve the directional stability. It will stop the vehicle for a short braking distance without losing it.

At the time of traction control, brake control, engine control by controlling the throttle opening adjustment actuator 11, and AT for gear shift control are performed.
Lockup control is performed via the controller 101. The controller 111 includes a throttle opening sensor 1
02, 103 and the signals from the vehicle speed sensor 104, the wheel speed signals from the wheel speed sensors 112FL to 112RR that detect the speeds of the wheels 7FL to 7RR, and the accelerator opening sensor 113 that detects the accelerator opening. The accelerator opening signal from the steering wheel, the steering wheel steering angle signal from the steering angle sensor 114 for detecting the steering wheel steering angle, and the mode signal from the manually operated switch 116 are input.

FIG. 8 shows the content of the traction control by the controller 111 focusing on the engine control and the brake control. In the figure, the target value for the engine (the target slip value of the driving wheels) is indicated by SET, and the target value for the brake is indicated by SET (SBT> SE).
T).

[0037] Until time point t ₁ before, a large slip on the drive wheels has not occurred, the engine control is not performed, thus the sub-throttle valve 12 is a full open throttle opening Tn (both the throttle valve 10 , 12, which is the combined opening of the throttle valves corresponding to the opening of the throttle valve with the smaller opening) is the main throttle opening TH · M corresponding to the accelerator opening.

[0038] In time point t _1, the slip value of the driving wheels, a significant slip incurred became the target value SET for the engine. In the embodiment, the traction control is started when the slip value of the drive wheels becomes equal to or more than SET, and at this time t ₁ , the throttle opening is reduced to the lower limit control value SM all at once. (Feedforward control). Then, after the SM is once set, the opening degree of the sub-throttle valve 12 is feedback-controlled so that the slip value of the drive wheels becomes the engine target value SET. At this time, the throttle opening Tn is equal to the sub-throttle valve opening TH.
It becomes S.

[0039] In t ₂ time is when the slip value of the driven wheel is equal to or greater than the brake target value SBT, this time, the drive wheel brake 21RL, brake fluid pressure is supplied to 21RR, and the engine control Traction control is started by both brake control. The brake fluid pressure is feedback-controlled so that the slip value of the drive wheel becomes the brake target value SBT.

[0040] In t ₃ time, the slip value of the driven wheel is at when a target value less than SBT for the brake, which brake fluid pressure is gradually lowered by, eventually brake fluid pressure becomes zero. However, the slip control by the engine is still continued.

The termination condition of the traction control is that the accelerator opening is fully closed in the embodiment.

The slip value of the driving wheel is measured by the wheel speed sensor 11
It is detected based on the detection signals from 2FR to 112RL. That is, the slip value is calculated by subtracting the rotational speed of the driven wheels from the rotational speed of the driving wheels.
When calculating the slip value, in the case of engine control, the larger one of the left and right drive wheels is selected as the rotation speed of the drive wheels, and the average value of the left and right driven wheels is used as the rotation speed of the driven wheels. In the case of brake control, the rotation speed of the driven wheels is the same as that of engine control, but the rotation speed of the drive wheels is the rotation speed of the left and right drive wheels when controlling the braking force on the left and right drive wheels independently of each other. Are used respectively.

FIG. 9 is a block diagram showing a circuit for determining the above target values SET and SBT. The determination parameters are vehicle speed, accelerator opening, steering wheel steering angle,
It includes the operating state of the mode switch 116 and the maximum friction coefficient μmax of the road surface.

That is, in the figure, the basic value STA0 of SET and the basic value STB0 of SBT are stored in the map 121 with the maximum friction coefficient as a parameter (S
TB0> STA0). Then, this basic value STB0, S
By multiplying TA0 by the correction gain coefficient KD, SET and SBT can be obtained.

The correction gain coefficient KD is obtained by multiplying the gain coefficients VG, ACPG, STRG and MODEG. The gain coefficient VG uses the vehicle speed as a parameter and is stored as the map 122. The gain coefficient ACPG has the accelerator opening as a parameter and is stored as the map 123.
The gain coefficient STRG uses the steering angle of the steering wheel as a parameter, and is stored as the map 124. The gain coefficient MODEG is manually selected by the driver and is stored in the table 125. This table 1
In 25, three types of sports mode, normal mode and safety mode are provided.

The steering angle sensor 114 is of an encoder type. That is, as shown in FIG. 3, the steering angle sensor 114 includes, for example, a disc 52 that is rotatably and integrally attached to the steering shaft 51, and a large number of outer slits 53, 53, ... , And a large number of inner slits 54, 54, ... Are opened at equal intervals in the circumferential direction on the radially inner side of the outer slits 53, 53 ,. It is placed just off. Further, two LEDs 55, 56 for projecting light toward the internal and external slits 53, 54 are arranged on one side of the disc 52, while the other LEDs passing through the slits 53, 54 on the other side. LED5
Two phototransistors 57 and 58 are provided to make the light from the light beams 5 and 56 respectively incident. Then, when the front wheels 7FL and 7FR are being steered, the two phototransistors 57 and 58 cause the light from the LEDs 55 and 56 to travel through the respective slits 53, as shown in FIG. When the light is input to the phototransistors 57 and 58 through 54, the outputs of the phototransistors 57 and 58 are set to "1", and the light is transmitted through the slits 53,
An output pulse signal that outputs "0" when it is not input to the phototransistors 57 and 58 by being disturbed by the disc 52 between 53 or 54 and 54 is output to the phototransistor 5
Depending on the output signal pattern and pulse number of 7,58,
The steering direction and steering angle are detected.

The output signals of the steering angle sensor 114 (both phototransistors 57 and 58) are (0, 0), (0,
1), (1,0), and (1,1), for example, the combination of signals output next to (0,0) is (0,
The combination of signals is repeated so as to be 1) or (1,0), but due to some cause, a frame skipping abnormality occurs in which the signal immediately shifts from (0,0) to (1,1). In order to deal with this abnormality, the controller 111 performs the control shown in FIG. That is, in step S1, the steering angle sensor 114
Is read, and it is determined in step S2 whether or not the frame skips. When there is no abnormality, the output signal of the steering angle sensor 114 is used as it is in step S3,
Then, in step S5, the above-mentioned anti-skid brake control and traction control are performed. On the other hand, when there is a frame skipping abnormality in the output signal of the steering angle sensor 114, the output signal of the steering angle sensor 114 is corrected to a signal in the direction in which the steering angle increases in step S4, and thereafter, in step S5 described above. The anti-skid brake control and traction control are performed using the correction value.

In this embodiment, step S in the above flow is performed.
2 constitutes an abnormality detecting means 131 for detecting an abnormality in the output signal of the steering angle sensor 114. Further, in step S4, when the abnormality detecting means 131 detects an abnormality in the output signal of the steering angle sensor 114, the steering angle sensor 114 outputs a signal input for the anti-skid brake control or traction control as the steering angle. A correction unit 132 that corrects the signal in the increasing direction is configured.

Therefore, in this embodiment, when an abnormality occurs in the output signal of the steering angle sensor 114, the signal input from the steering angle sensor 114 to the controller 111 is corrected to a signal in the direction of increasing the steering angle. By the correction to the signal in the direction in which the steering angle increases, for example, in the traction control, the control in the direction in which the vehicle spin is suppressed is performed, and the running stability of the vehicle is improved even when the output signal of the steering angle sensor 114 is abnormal. Can be secured.

[0050]

As described above, according to the first aspect of the invention, the steering angle of the vehicle detected by the encoder type steering angle sensor is used as a control element, and the control threshold value is changed according to the steering angle. In the slip control device such as anti-skid brake device and traction control device
If an output abnormality of the steering angle sensor is detected and the signal input to the control means from the steering angle sensor is corrected to a signal in the direction in which the steering angle increases, slip control is performed even when the steering angle sensor is abnormal. The traveling stability of the vehicle controlled by the device can be ensured.

[Brief description of drawings]

FIG. 1 is a configuration diagram of the present invention.

FIG. 2 is a flowchart showing a signal processing procedure in a controller in the embodiment of the present invention.

FIG. 3 is a schematic perspective view of a steering angle sensor.

FIG. 4 is a diagram showing an output signal waveform of a steering angle sensor.

FIG. 5 is a configuration diagram of a slip control device according to an embodiment of the present invention.

FIG. 6 is a characteristic diagram showing a relationship between a slip ratio, a friction coefficient, and a lateral drag coefficient.

FIG. 7 is a time chart diagram in anti-skid brake control.

FIG. 8 is a time chart diagram in traction control.

FIG. 9 is a circuit diagram for determining respective slip target values for an engine and a brake.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Engine 3 ... Automatic transmission 7FL, 7FR ... Front wheels (steering wheels) 7RL, 7RR ... Rear wheels 21FL to 21RR ... Brake 101 ... AT controller 111 ... Controller 114 ... Steering angle sensor 131 ... Abnormality detection means 132 ... Correction means

Claims (1)

[Claims] 1. An encoder type steering angle sensor for detecting a steering angle of steered wheels, and a control means for controlling so as to change a control threshold value of a slip control amount according to a steering angle detected by the steering angle sensor. In a slip control device provided with the steering angle sensor, an abnormality detecting means for detecting an abnormality in the output signal of the steering angle sensor, and a steering angle sensor when an abnormality in the output signal of the steering angle sensor is detected by the abnormality detecting means. A slip control device comprising: a correction unit that corrects a signal input from the control unit to the control unit to a signal in a direction in which the steering angle increases.