Abstract: There is provided a control system for a hybrid vehicle. When it is detected that an ignition power supply line has been cut off (that an ignition switch has been switched OFF) during EV travel realized by disengaging a transmission clutch, a self-shut function is stopped while keeping a switching transistor of a self-shut line ON, and the transmission clutch is maintained in a disengaged condition by keeping a transmission clutch actuator energized.

Abstract: To maintain operating safety by driving force distribution control system when an abnormal state arises and to smoothly transition from a normal state to an abnormal state without sudden changes in vehicle behavior. The driving force distribution control part calculates the transfer torque for the transfer clutch for the center differential device and the torque movement for the hydraulic motor for the rear wheel final reduction gear. When the control state detection part detects an abnormal state, there is control of the hydraulic motor in the direction that torque movement is lost on the one hand, and the transfer torque for the transfer clutch is controlled in the direction of front and rear distribution; after a preset time and after this control is carried out, the transfer torque drops.

Abstract: With a drive power distribution control section, limited differential torque correction value TLSDS is estimated and calculated by a limited differential torque correction value calculating section based on input torque TCD. Also, a transfer torque calculating section calculates transfer torque TLSD2 by multiplying input torque sensing transfer torque TLSD1 by vehicle slip angular velocity correction coefficient K(d?/dt). A transfer torque correction/output section then subtracts limited differential torque correction value TLSDS from the transfer torque TLSD2 to calculate and output transfer torque TLSD. In this way, clutch engaging torque for carrying out front and rear drive power distribution is set with good accuracy, and it is possible to have both high cornering performance and high traction performance.

Abstract: A drive power distribution control section calculates an engaging torque of clutch means including an input torque sensitive transfer torque, a steering angle/yaw rate sensitive transfer torque, and a tack-in prevention transfer torque. The input torque sensitive transfer torque is estimated by using respective time constants corresponding to an increasing or decreasing of the engine torque. Also, when the input torque is large, a variation of the input torque sensitive transfer torque is increased. The steering angle/yaw rate sensitive transfer torque is corrected by an yaw moment according to an vehicle slip angular velocity, and an upper limit is set on the variation of the yaw moment per time.

Abstract: To maintain operating safety by driving force distribution control system when an abnormal state arises and to smoothly transition from a normal state to an abnormal state without sudden changes in vehicle behavior. The driving force distribution control part calculates the transfer torque for the transfer clutch for the center differential device and the torque movement for the hydraulic motor for the rear wheel final reduction gear. When the control state detection part detects an abnormal state, there is control of the hydraulic motor in the direction that torque movement is lost on the one hand, and the transfer torque for the transfer clutch is controlled in the direction of front and rear distribution; after a preset time and after this control is carried out, the transfer torque drops.

Abstract: With a drive power distribution control section, limited differential torque correction value TLSDS is estimated and calculated by a limited differential torque correction value calculating section based on input torque TCD. Also, a transfer torque calculating section calculates transfer torque TLSD2 by multiplying input torque sensing transfer torque TLSD1 by vehicle slip angular velocity correction coefficient K(d?/dt). A transfer torque correction/output section then subtracts limited differential torque correction value TLSDS from the transfer torque TLSD2 to calculate and output transfer torque TLSD. In this way, clutch engaging torque for carrying out front and rear drive power distribution is set with good accuracy, and it is possible to have both high cornering performance and high traction performance.

Abstract: A drive power distribution control section calculates input torque sensing transfer torque by first transfer torque calculating section, steering angle/yaw rate sensing transfer torque by second transfer torque calculating section, and tack-in prevention transfer torque by third transfer torque calculating section. At this time, input torque sensing transfer torque is estimated using respective time constants for increasing and decreasing engine torque. Also, in a region where input torque is large, a variation amount is increased. The steering angle/yaw rate sensing transfer torque corrects yaw moment, and in correction of an absolute value of the yaw moment towards a larger value a limit is provided based on a previous correction result.

Abstract: A temporary indicated torque is obtained by taking a conventional dead zone area for a first slip control area, and the value proportional to the slip quantity for a maximum value, this temporary indicated torque is corrected by a correction value according to the tight cornering brake quantity to be the indicated torque of the transfer clutch, and occurrence of any tight cornering brake phenomenon is prevented thereby. In a slip control area after passing a dead zone area (a second slip control area), the slip control is smoothly transferred from the first slip control area to the second slip control area by performing the slip control with a value of the indicated torque according to the slip quantity added to the indicated torque in the first slip control area as the indicated torque, abrupt torque change is prevented, and the vehicle behavior is stabilized thereby.

Abstract: In a specific control state, confirmation is made whether or not the present torque limiter value exceeds a maximal value of an allowed torque value in the specific control state, and in the event that the present torque limiter value exceeds the maximal value of the allowed torque value in the specific control state, the torque limiter value is slowly lowered by subtracting a constant A1 from the present torque limiter value, while in the event of transition from the specific control state to an ordinary control state, the torque limiter value is slowly raised to the maximal torque limiter value in the ordinary control state by adding a constant A2 to the present torque limiter value. Thus, excessive change of torque at transition of a control state can be suppressed, and adverse effects on driving stability and driving performance under the specific control state can be minimized.

Abstract: When vehicle behavior control systems such as VDC, TCS, ABS and the like are operative, a front-rear power distribution control apparatus for a four wheel drive vehicle can have an excellent convergence characteristic in vehicle behavior control by choosing a transfer clutch torque from a region of a predetermined table in which the power distribution control does not interfere with the behavior control of the vehicle behavior control system and by establishing the transfer clutch torque to a larger value with an increase of transfer input torque. When the vehicle is in an understeer or oversteer tendency, the convergence of vehicle behavior is further enhanced by correcting the transfer clutch torque in an increasing or decreasing direction.

Abstract: In a specific control state, confirmation is made whether or not the present torque limiter value exceeds a maximal value of an allowed torque value in the specific control state, and in the event that the present torque limiter value exceeds the maximal value of the allowed torque value in the specific control state, the torque limiter value is slowly lowered by subtracting a constant A1 from the present torque limiter value, while in the event of transition from the specific control state to an ordinary control state, the torque limiter value is slowly raised to the maximal torque limiter value in the ordinary control state by adding a constant A2 to the present torque limiter value. Thus, excessive change of torque at transition of a control state can be suppressed, and adverse effects on driving stability and driving performance under the specific control state can be minimized.

Abstract: A temporary indicated torque is obtained by taking a conventional dead zone area for a first slip control area, and the value proportional to the slip quantity for a maximum value, this temporary indicated torque is corrected by a correction value according to the tight cornering brake quantity to be the indicated torque of the transfer clutch, and occurrence of any tight cornering brake phenomenon is prevented thereby. In a slip control area after passing a dead zone area (a second slip control area), the slip control is smoothly transferred from the first slip control area to the second slip control area by performing the slip control with a value of the indicated torque according to the slip quantity added to the indicated torque in the first slip control area as the indicated torque, abrupt torque change is prevented, and the vehicle behavior is stabilized thereby.