Mazda Motor Corporation

Kaoru Sotoyama

Kazutoshi Nobumoto

Toshiaki Tsuyama

Kenichi Watanabe

Toshihiro Matsuoka

Mitsuru Nagaoka

Eizi Nishimura

Eiji Nishimura

Haruki Okazaki

Fumio Kageyama

Osamu Kameda

Toru Onaka

Shizuo Sumida

Makoto Kawamura

Toshiyuki Kikuchi

Yasunari Nakayama

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.

Vehicle slip control system

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 slip of the driven wheels is converged by causing the torque generated by the engine to be reduced and applying braking force when a slip of the driven wheel becomes large during accelerating. Control of the application of the braking force to the left-hand and right-hand driven wheels is made individually and separately from each other. When such an incident occurs as causing no normal control of decreasing the torque generated by the engine to be made, the contents of control of application of the braking force is changed so as to apply the same degrees of the braking force to both of the left-hand and right-hand driven wheels.

Slip control system for automotive vehicle

In a slip control system for a vehicle a slip ratio of driving wheels of the vehicle is detected, and the slip of the driving wheels is controlled to converge on a predetermined target slip ratio when the slip ratio of the driving wheels exceeds a predetermined threshold slip ratio. When the vehicle is running a rough road, the threshold slip ratio is increased. The running condition of the vehicle is detected and increase of the threshold slip ratio is inhibited depending on the running condition of the vehicle.

Slip control system for vehicle and rough road detecting system

A drive control system of a four-wheel drive vehicle has a differential device interposed between front and rear wheels and a differential restricting device mounted to the differential device. The differential restricting device is subjected to feedback control so as for the wheels to reach a target slip ratio. In this control, a control target value is given by way of slip ratios of the wheels and the target slip ratios are then converted into a wheel speed difference between the front and rear wheels. The feedback control of the differential restricting device is performed by comparing the target wheel speed difference with an actual wheel speed difference between the front and rear wheels.

Drive control system of four-wheel drive vehicle

Disclosed is a four wheel drive vehicle with four wheels drivable, which is provided with a first slip control apparatus for reducing a driving force to the wheels by operating a brake mounted on each of the wheels and with a second slip control apparatus for reducing a driving force to the wheels by reducing the engine output. Operation of only the first slip control apparatus or both the first and second slip control apparatuses is selectively carried out in accordance with the number of wheels which are detected to be slipping in an amount greater than a given degree of slippage. Particularly when such slipping wheels are two, the slip control is conducted by operating only the first slip control apparatus or both the first and second slip control apparatuses in accordance with control modes predetermined on the basis of six combinations in which such two slipping wheels out of the four wheels are combined with each other.

Slip control apparatus for a four wheel drive vehicle

An automatic speed control system for a vehicle includes an automatic transmission, a speed change switch for producing signals for changing a vehicle speed, and a shift down control device. The shift down control device carries out a shift down operation of the automatic transmission of the vehicle under a certain vehicle driving condition when the shift down control device receives the signals from the speed change switch. A gradient detecting device detects a gradient of a running path on which the vehicle is driven, and shift down prohibiting device prohibits the shift down operation even where the speed change switch is actuated to the vehicle speed at least when the gradient of a running path detected is greater than a predetermined value so that unnecessary shift changes are suppressed.

Automatic speed control system for vehicle

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

An engine control apparatus includes an operation amount detection section for detecting an operation amount of an acceleration pedal, a throttle valve for adjusting an engine output, an arithmetic section for receiving the output from the operation amount detection section and calculating a control amount corresponding to the output operation amount of the acceleration pedal in accordance with a predetermined characteristic, the control amount being one for controlling the throttle valve, a motor for receiving the output from the arithmetic section and driving the throttle valve in accordance with the control amount calculated by the arithmetic section, a return detection section for detecting a return state of the acceleration pedal, and a control section for, when the return detection section detects the return state of the acceleration pedal, controlling the arithmetic section to output the control amount in accordance with a characteristic with which the engine output is decreased below that according to the predetermined characteristic.

Engine control apparatus

A vehicle automatic transmission including a torque converter and a multiple stage transmission gear mechanism. The gear mechanism is controlled through a hydraulic system having solenoid valves. An electronic control unit is provided to control the hydraulic system under a shift control map having shift up and shift down control lines. The shift down control line is determined in terms of the torque converter turbine speed and the engine throttle valve position as a line in which the torque converter is operated with a torque ratio of substantially one.

Control means for vehicle automatic transmissions

A vehicle automatic transmission including a torque converter having a lock up clutch. A lock up control circuit is provided and has a memory including a first lock up control line for controlling the engagement and release of the lock up clutch when the torque converter turbine speed is close to the pump impeller speed, and a second lock up control line which is drawn along a line wherein the engine output torque is substantially zero so that the lock up clutch is released at a given engine load when the turbine speed is decreased beyond the first lock up control line, or when the turbine speed is increased beyond the second lock up control line.

Lock up control of a hydraulic torque converter type automatic

A vehicle automatic transmission including a torque converter and a multiple stage transmission gear mechanism. The gear mechanism is controlled through a hydraulic system having solenoid valves. An electronic control unit is provided to control the hydraulic system under a shift control map having shift up and shift down control lines. The shift down control line is determined in terms of the torque converter turbine speed and the engine throttle valve position as a line passing through points of maximum curvature on iso-engine-output-power lines as functions of the torque converter turbine speed and the engine load.

A lock-up mechanism for a torque converter for an automatic transmission is arranged to be selectively engaged to directly connect the output shaft and the input shaft of the torque converter when the operating condition of the engine is in a lock-up zone. The operating condition of the engine is represented by a rotational speed signal representing the rpm of the input shaft or the output shaft of the torque converter, and an engine load signal, and the lock-up zone is defined by first to third relations, the first relation being preset from a relation which the rotational speed and the engine load are to have with each other when the torque ratio of the engine output torque to the torque converter output torque can be considered to be 1, the second relation being preset from a relation which the rotational speed and the engine load are to have with each other when the engine output may be considered to be zero, and the third relation being preset from a lower limit of the rotational speed at which lock-up can be permitted without possibility of engine stall. The lower limit is shifted toward the lower speed side of the rotational speed as the transmission stage of the transmission gear mechanism is shifted toward the higher speed stage, and the third relation is changed corresponding to the change in the lower limit of the rotational speed.

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Hiroshima, Japan

Kaoru Sotoyama