Mazda Motor Corporation

Sumitomo Electric Industries, Limited

Fumio Kageyama

Kazutoshi Nobumoto

Toshiaki Tsuyama

Haruki Okazaki

Makoto Kawamura

Toru Onaka

Akira Sone

Hiroshi Ohmura

Takeshi Edahiro

Masato Yoshino

Kaoru Sotoyama

Takeshi Murai

Ryuya Akita

Takashi Nakashima

Yoji Kurihara

Shunsuke Kawasaki

Shinji Umehira

Hirotaka Kanazawa

Toshiki Morita

Masaru Shiraishi

Tetsuya Tachihata

Tomoyuki Hirao

Makoto Teshima

Atuo Tomoda

Shin Takahara

A road surface condition determining system for an automotive vehicle equipped with a traction control feature determines, while the traction control is being executed, a first road surface friction coefficient on the basis of a vehicle speed and longitudinal acceleration and a second road surface friction coefficient on the basis of driving torque applied to the driving wheels and selects, as an eventual road surface friction coefficient, either one of the first and second road surface friction coefficients which is larger than the other.

Road surface condition determining system

A traction control system for a vehicle reduces the rate of slip of driving wheels of the vehicle by reducing the traction force transmitted to the road surface from the driving wheels when the driving wheels slip. Whether the vehicle is making a turn is judged, and whether the vehicle is in an instable state which occurs when the vehicle is making a turn. The traction force is reduced by a higher rate when the driving wheels slip while the vehicle is making a turn than when the driving wheels slip while the vehicle is running straight, and the traction force is reduced by a higher rate when the driving wheels slip while the vehicle is in an instable state than when the driving wheels slip while the vehicle is making a turn.

Traction control system for vehicle

A slip control system for a motor vehicle controls slippage of driving wheels and includes a sensor for detecting a slip ratio of each driving wheel, a device for decreasing slip of each driving wheel by controlling a driving force transmitted to the driving wheel so that the slip ratio of the driving wheel is at least equal to a predetermined desired slip ratio when the slip ratio of the driving wheel is equal to the desired slip ratio, a sensor for detecting a yawing rate of the vehicle, and a sensor for detecting a steering amount of the vehicle. The slip decreasing device includes a correcting device for decreasing the desired slip ratio when a steering condition is detected based on amounts detected by both the yawing rate detecting sensor and the steering amount detecting sensor.

Slip control system for motor vehicle

A slip control system for a vehicle having rear right and left drive wheels includes a traction control for controlling a slip rate of a wheel by controlling a braking hydraulic pressure for the wheel under a non-braking condition. The slip rate of a wheel is controlled, by controlling the braking hydraulic pressure for the wheel under a braking condition, so as to provide an anti-skid control. A start of the control of the slip rate is restricted by the anti-skid control. The control of the slip rate by the anti-skid control is applied commonly to the right and left drive wheels, while the control of the slip rate by the traction control is applied independently to the right and left drive wheels. The anti-skid control can be always properly carried out without being affected by the traction control.

Vehicle slip control system

The braking force to the driven wheels is subjected to feedback control so as to allow the actual slip value of the driven wheels to agree with a predetermined target value for controlling the brake. The control amount for the feedback control is determined by differentiation control. The feedback control amount contains a first control amount corresponding to a predetermined basic travelling state and a second control amount corresponding to a particular travelling state. In ordinary travelling state, the braking force is controlled by the first control amount, and the braking force is controlled by the second control amount when the automotive vehicle is travelling in such a particular state. When the the vehicle is travelling on a bad road, the second control amount is set so as to loosen the braking force, as compared with the first control amount. Alternatively, when the vehicle is cornering, the second control amount is set as to tighten the braking force as compared with the first control amount.

Traction control system for automotive vehicle

A slip control device includes a slip detecting device for detecting a slip rate of a drive wheel, an engine control device for reducing an engine output when the slip rate exceeds a first threshold value, and a brake control device for applying a brake force on the drive wheel when the slip rate exceeds a second threshold value. A frictional coefficient detecting device detects a frictional coefficient of a road, on which the vehicle is running, and a threshold determining device provides the first and second threshold values in accordance with the frictional coefficient. The engine output control and brake force control can be effectively utilized for the slip control in the traction control.

Slip control device for vehicle wheel

A traction control system for a vehicle has a sub-throttle valve provided in an intake passage of the engine in series to a main throttle valve which is operatively connected to an accelerator pedal to open and close in response to operation of the accelerator pedal. An engine output controller controls opening of the sub-throttle valve to control the output of the engine so that the slip value of the driving wheels converges on a target slip value. The engine output controller once moves the sub-throttle valve to an initial opening when the slip value of the driving wheels exceeds the target slip value and then controls the opening of the sub-throttle valve to control the output of the engine so that the slip value of the driving wheels converges on a target slip value. The initial opening is set to be a fixed value when the opening of the main throttle valve is not larger than a predetermined opening and to be substantially equal to the opening of the main throttle valve when the opening of the main throttle valve is larger than the predetermined opening. The fixed value is not smaller than the predetermined opening of the main throttle valve.

A slip control system for a motor vehicle controls respective braking forces in right and left driving wheels and controls an engine output by controlling a throttle opening of a throttle valve so that a slip value of the driven wheel becomes less than a target slip value. The system includes a device providing a basic control amount of the throttle opening based on the slip value of the driven wheel and the target slip value, a device for detecting respective brake fluid pressures in the right and left driven wheels, a device for converting the detected brake fluid pressure into an engine output, a device for providing a correction control amount of the throttle opening by subtracting an amount of the throttle opening corresponding to the converted engine output from the basic control amount of the throttle opening, and a device for driving the throttle valve by the basic control amount of the throttle opening when the brake fluid pressures in the right and left driven wheels are increased or increased rapidly, and driving the throttle valve by the correction control amount of the throttle opening when the brake fluid pressures in the right and left driven wheels are not increased or increased rapidly.

An antilock control device for the brake assembly of a motor vehicle having the function of detecting ON and OFF signals supplied from a brake lamp switch and representative of the operative and inoperative positions of the brake pedal. When the signal changes from OFF to ON, which means that the brake pedal has been trodden, the antilock control function is disabled so that the pressure generated in the master cylinder will be directly applied to the wheel cylinders. This state continues until the antilock device detects a locking tendency of any wheel. In addition to the brake lamp switch signals, signals representative of the ON and OFF positions of the accelerator pedal may be supplied to the antilock control device so that the antilock control function will be disabled when either the accelerator pedal position signal changes from OFF to ON or the brake pedal position signal changes from ON to OFF.

Antilock control device

A slip control system for a vehicle having a differential which distributes engine output to left and right driving wheels suppresses the engine output when the slip of at least one of the driving wheels exceeds a first threshold value. Slips of the left and right driving wheels are periodically detected, and a spin pattern of the driving wheels is periodically determined on the basis of the slips of the left and right driving wheels. Whether the vehicle is running on a split surface road, where the parts of the road surface in contact with the left and right driving wheels have different friction coefficients, is determined on the basis of the present spin pattern and the preceding spin pattern according to a predetermined split surface determining rule. When it is determined that the vehicle is running on a split surface road, the first threshold value is increased.

A slip control system for a motor vehicle controls slips in driving wheels and includes a sensor for detecting a slip ratio of each driving wheel and a traction control system for decreasing a slip of each driving wheel by controlling a driving force transmitted to each driving wheel so that the slip ratio of each driving wheel is at least equal to a predetermined desired slip ratio when the slip ratio of the driving wheel becomes equal to the desired slip ratio. An automatic transmission control system controls an automatic transmission by using a first shift property for a normal operation, and a second shift property for a traction control operation which is adapted to determine a relative higher speed stage. A device is provided for switching the first shift property to the second shift property when the traction control operation is started by the traction control system.

An anti-skid brake system for the automotive vehicle is disclosed which is arranged to increase or decrease the braking oil pressure periodically on the basis of a comparison between the wheel speed and the assumed vehicle body speed. When the state in which the wheel is incipient to lock before the wheel speed is returned to the assumed vehicle body speed, the braking oil pressure is inhibited from being increased, thereby preventing the assumed vehicle body speed from deviating too far from the actual vehicle body speed. This anti-skid brake system can prevent the wheel from being locked due to having the assumed vehicle body speed set to too low a value relative to the actual wheel speed.

Anti-skid brake system for an automotive vehicle

A rear steering control system for a motor vehicle includes an antiskid braking system which controls a braking force in a brake device in a respective wheel in accordance with a deceleration condition of the respective wheel so as to prevent wheel locking in a braking operation. The sytem includes a rear steering control system for establishing a ratio of steering amount of the rear wheels to that of the front wheels as a predetermined steering ratio characteristic. An input device inputs an operation condition of the antiskid braking system and an control condition of the brake device for the respective wheel conducted by the antiskid braking system to the rear steering control system. A device is provided in the system for amending the predetermined steering ratio characteristic in accordance with the control condition of the brake device for the respective wheel when the antiskid braking system is in operation.

Rear wheel steering system for motor vehicle

A shift to control for retaining the braking force from the control for elevating the braking force is implemented when deceleration of the wheel exceeds a first predetermined threshold value when the wheels are braked. The first predetermined threshold value is so set as to become smaller as an assumed road surface friction coefficient .mu. is smaller. The first threshold value is further altered to a larger value by altering the assumed road surface friction coefficient .mu. to a higher one when the period of time required from the start of the control for elevating the braking force to the start of the following control for retaining the braking force is equal to or shorter than a predetermined period of time.

Anti-skid brake system with reset of thresholds due to changing road

A first estimated vehicle speed is calculated on the basis of the highest of the speeds of the wheels and the deceleration of the vehicle. A second estimated vehicle speed which begins to reduce from a predetermined value at a predetermined rate independent from the change in the highest of the speeds of the wheels from the time the first estimated vehicle speed falls to the predetermined value is calculated. A slip ratio of each wheel is calculated on the basis of the first estimated vehicle speed when the first estimated vehicle speed is not lower than the predetermined value and on the basis of the second estimated vehicle speed when the first estimated vehicle speed is lower than the predetermined value. The braking force applied to each wheel is controlled so that the slip ratio of the wheel converges on a target slip ratio.

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Hiroshima, Japan

Fumio Kageyama