Mazda Motor Corporation

Toru Onaka

Toshiaki Tsuyama

Kazutoshi Nobumoto

Fumio Kageyama

Makoto Kawamura

Haruki Okazaki

Yasuhiro Harada

Eizi Nishimura

Toshihiro Matsuoka

Mitsuru Nagaoka

Kaoru Sotoyama

Yutaka Tsukahara

Yoji Kurihara

Akira Sone

Kazuya Oda

Makoto Teshima

A traction control device operates to determine the speed of each of the left and right drive wheels of a vehicle, determine the speed of each of the left and right passive wheels of the vehicle, calculate the actual slip rate of the drive wheels of the vehicle directly based on the measurements of the speeds for the drive and passive wheels, establish a target slip rate and control the driving condition of the vehicle by making the actual slip rate equal the target slip rate. The actual slip rate is matched to the target slip rate by controlling engine output and braking power. The step of controlling the driving condition of the vehicle by controlling the engine output and the braking power is carried out according to the time differential of the difference between the actual slip rate and the target slip rate at least until the actual slip rate matches the target slip rate for the first time. After the actual slip rate has matched the target slip rate at least once, the step of controlling is carried out according to the proportion of the difference between the actual and the target slip rates.

Traction control device for vehicles

A traction control system for a motor vehicle having driving wheels and driven wheels includes a device for detecting the speed of each of the driving wheels of the vehicle, a device for detecting the speed of each of the driven wheels of the vehicle, a device for calculating a slip value of the driving wheels based on the detected speeds of the driving and driven wheels, a traction control device for controlling the driving wheel so that the slip value of each driving wheel is equal to a predetermined desired slip value when the slip value of each driving wheel is greater than the predetermined desired slip value, and a device for estimating a friction coefficient of a road surface which is employed when the predetermined desired slip value is determined. If slip of the driving wheel occurs when the vehicle is started, the estimating device calculates an acceleration of the driving wheel. The friction coefficient of the road surface is estimated based on an engine output when the acceleration of the driving wheel is greater than a predetermined value.

Traction control system using estimated road surface friction coefficient

A vehicle slippage control system has wheel drive torque controlled so as to prevent drive wheels from excessively slipping on a road and is regulated in accordance with road surface resistances. The system estimates lateral and rectilinear road surface resistances on the basis of lateral and rectilinear gravitational acceleration of the vehicle, respectively, and then selects one of the estimated lateral and rectilinear road surface resistances, on the basis of predetermined terms, as an effective road surface resistance in accordance with which wheel drive torque is changed.

Slippage control system using estimated road surface resistances

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 traction control system for a motor vehicle having driving wheels and driven wheels includes a device for detecting the speed of each of the driving wheels of the vehicle, a device for detecting the speed of each of the driven wheels of the vehicle, a device for calculating a slip value of the driving wheels based on the detected speeds of the driving and driven wheels, a traction control device for controlling the driving wheel so that the slip value of each driving wheel is equal to a predetermined desired slip value when the slip value of each driving wheel is greater than the predetermined desired slip value, and a device for estimating a friction coefficient of a road surface which is employed when the predetermined desired slip value is determined. The estimating device calculates, in a first predetermined time period immediately after the traction control is started, an acceleration of the driven wheel based on a speed difference of the driven wheel during a second predetermined time period and an acceleration of the driven wheel based on a speed difference of the driven wheel during a third predetermined time period after the first predetermined time period has passed. The estimating device then estimates the friction coefficient of the road surface by using the calculated acceleration of the driven wheel.

Traction control system for motor vehicle

A traction control system for a motor vehicle having driving wheels and driven wheels includes a device for detecting the speed of each of the driving wheels of the vehicle, a device for detecting the speed of each of the driven wheels of the vehicle, a device for calculating a slip value of the driving wheels based on the detected speeds of the driving and driven wheels, a traction control device for controlling the driving wheel so that the slip value of each driving wheel is equal to a predetermined desired slip value when the slip value of each driving wheel is greater than the predetermined desired slip value, and a device for estimating a friction coefficient of a road surface which is employed when the predetermined desired slip value is determined. The estimating device updates the friction coefficient of the road surface previously estimated with the friction coefficient of the road surface newly estimated when the slip value of the driving wheel is located in a predetermined region.

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.

Traction control system for vehicle

A slip control system is so adapted as to start the control of the braking force from a state in which the braking force is reduced when a magnitude of deceleration of the wheel becomes equal to or larger than a predetermined value or when a slip value of the wheel becomes a value in the direction in which the wheel is likely to be locked and as to start the control of the braking force from a state in which the braking force is sustained when the deviation obtained by subtracting the wheel speed from the vehicle speed becomes equal to or larger than a predetermined value. This arrangement satisfies requirements for both preventing the wheel from being locked and shortening the braking distance.

Slip control system for an automotive vehicle

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

An assumed vehicle body speed is determined on the basis of the wheel speed detected by a wheel speed sensor for each wheel and a slip value indicating the tendency of locking the wheel is determined for a predetermined wheel speed on the basis of the assumed vehicle body speed and a wheel speed of the predetermined wheel. The braking force is controlled on the basis of the slip value. When no braking force is controlled and when at least one of the wheel speeds for all the wheels detected by the wheel speed sensors is larger than the assumed vehicle body speed previously determined, a new assumed vehicle body speed which follows is inhibited from being renewed to a larger value and the new assumed vehicle body speed is set as a value equal to the previous assumed vehicle body speed.

Anti-skid brake system for an automotive vehicle including brake force

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.

Anti-skid 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 detecting a reduction in speed of each wheel, and a traction control system for decreasing a slip of each driving wheel by controlling brake fluid pressure in 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 each driving wheel becomes equal to the desired slip ratio. The system further includes an antiskid brake system for controlling brake fluid pressure, based on the reduction speed of each wheel, so as to cancel a lock condition of the wheel. The antiskid brake system has a first control device for controlling the brake pressure fluid in a condition in which a traction control operation is not carried out by the traction control system, and a second control device for controlling the brake pressure fluid in a condition in which a traction control operation is carried out by the traction control system.

Slip control system for motor vehicle

A shift is implemented from the control for elevating the braking force to the control for retaining the braking force 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.

A braking force control system controls the brake fluid pressure applied to the wheel during braking when each of the wheels of the vehicle tends to lock so that the slip ratio of the wheel converges on a target slip ratio. The brake fluid pressure is once fixed at the beginning of the braking force control, and when the slip ratio falls below the target slip ratio by fixing the brake fluid pressure, the brake fluid pressure is increased at a first rate, and when the slip ratio does not increase to a predetermined slip ratio in a predetermined time after the slip ratio falls below the target slip ratio or when the rate of increase of the slip ratio after the slip ratio falls below the target slip ratio is lower than a predetermined rate, the brake fluid pressure is increased at a second rate which is higher than the first rate.

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Hiroshima, Japan

Toru Onaka