Mazda Motor Corporation

Eizi Nishimura

Kazutoshi Nobumoto

Kaoru Sotoyama

Toru Onaka

Toshihiro Matsuoka

Mitsuru Nagaoka

Yasuhiro Harada

Toshiaki Tsuyama

Osamu Kameda

Kenichi Watanabe

A four-wheel drive vehicle has a center differential which transmits the output torque of a power plant to both front and rear wheels in such a manner as to permit the front and rear wheels to rotate at different speeds. A differential control system has a differential rotation limit member which acts on the center differential to limit differential rotation of the front and rear wheels to a degree which is increased as the difference in rotational speed between the front and rear wheels increases. The degree of limitation on the differential rotation of the front and rear wheels is changed according to a predetermined characteristics which nullifies the degree of limitation in a range where the difference in rotational speed is relatively small and provides a gain in a range where the difference in rotational speed is relatively large. The gain is changed according to a factor which governs the running condition of the vehicle.

Differential control system for four-wheel drive vehicle

A four-wheel drive vehicle has a center differential which transmits the output torque of a power plant to both front and rear wheels in such a manner as to permit the front and rear wheels to rotate at different speeds. A differential control system has a differential rotation limit member which acts on the center differential to limit differential rotation of the front and rear wheels to a degree which is determined according to the difference in rotational speed between the front and rear wheels. The degree of limitation on the differential rotation of the wheels is determined according to the difference in rotational speed between the front and rear wheels based on first characteristics when the rotational speed of the front wheels is higher than that of the rear wheels and based on second characteristics when the rotational speed of the rear wheels is higher than that of the front wheels. The first and second characteristics are set separately from each other.

A constant-speed cruising control system for a vehicle having an automatic transmission includes a vehicle speed controller which controls the throttle valve of the engine on the basis of the difference between a target vehicle speed and the actual vehicle speed so that the latter approaches the former, a gear shifting mechanism which receives a gear shifting command and shifts the gear stage of the automatic transmission according to the content of the gear shifting command which it receives, and a gear-shifting controller which receives an engine load signal representing the load on the engine and a speed difference signal representing the difference between said target vehicle speed and the actual vehicle speed, and delivers to the gear shifting mechanism a gear shifting command which requires the gear shifting mechanism to shift the gear stage down either when the load on the engine is not lighter than a first preset value or when the load on the engine is lighter than the first preset value and heavier than a second preset value and at the same time the difference between the target vehicle speed and the actual vehicle speed is larger than a preset speed.

Constant-speed cruising control system

An automatic transmission control system for controlling an automatic transmision for use in a vehicle provided with a throttle control system which electrically controls a throttle valve to control the engine output according to the amount of depression of the accelerator pedal and a constant-speed cruising control system which makes the vehicle cruise at a desired constant speed includes a first gear-stage setting system which designates a gear stage of the automatic transmission on the basis of a first gear-shifting pattern, which applies when the constant-speed cruising control is not performed, and in which the gear stages of the automatic transmission are related to the detected amount of depression of the accelerator pedal and the vehicle speed or a value corresponding to the vehicle speed, and a second gear-stage setting system which designates a gear stage of the automatic transmission on the basis of a second gear-shifting pattern, which applies when the constant-speed cruising control is performed in which the gear stages of the automatic transmission are related to the vehicle speed or a value corresponding to the vehicle speed, and a variable independent of the detected amount of depression of the accelerator pedal.

Automatic transmission control system for a vehicle having

The vehicle slip control apparatus is designed so as to enable the slip control to be done by causing the output torque of the engine to be reduced and operating the brake when an amount of a slip or spinning of the driven wheels is large. A control ratio of the slip control by the brake to the slip control by the engine is altered to an optimum value in accordance with requirements for the driving of the vehicle.

Vehicle slip control apparatus

The slip control is conducted so as to cause an amount of the slip of the driven wheel to become a target value by controlling the torque to be transmitted to the driven wheel. The target value is altered during the slip control on the basis of a requirement for road holding capabilities of the driven wheel against a road surface.

The vehicle slip control apparatus is designed so as to enable the slip control to be done by causing the output torque of the engine to be reduced and operating the brake when an amount of a slip or spinning of the driving wheels is large, on the one hand, and only by causing the output torque of the engine to be reduced without using the brake when an amount of the slip or spinning of the driving wheels is small.

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Hiroshima, Japan

Eizi Nishimura