Abstract: In response to detection of a slip-down of a vehicle under restriction of a motor torque Tm*, which is required for a drive shaft linked with drive wheels, due to the occurrence of a slip caused by spin of the drive wheels on an ending slope, the technique of the invention multiplies a torque insufficiency by a ratio (reflection ratio ?) specified according to a vehicle speed V in a t direction, so as to set a brake tourgue Tb*. The torque insufficiency corresponds to a difference between the restricted motor torque Tm* and a balancing torque Tgrad corresponding to a road surface gradient set according to the relation between an acceleration of the vehicle and a torque output to the drive shaft The setting of the brake torque Tb* makes the velocity of the slip-down of the vehicle approach to a preset vehicle speed. The brake torque Tb* is applied by hydraulic brakes attached to driven wheels which am different from the drive wheels.

Abstract: Under the condition of a large variation in motor torque demand, the significant torque change may lead to some vibration of a vehicle to temporarily heighten an angular acceleration. The temporary rise of the angular acceleration may cause the angular acceleration to exceed a preset threshold value slip and result in misdetection of the occurrence of a ‘phantom’ skid in an angular acceleration—based skid state determination. The drive control of the invention accordingly specifies a potential for misdetection of the occurrence of a ‘phantom’ skid when the variation in motor torque demand exceeds a preset threshold value at step S108. The drive control thereby does not execute skid occurring state control with torque restriction but performs grip state control at step S116.

Abstract: A vehicle is equipped with a motor that receives a supply of electric power, which is output from a battery and is boosted up by a DC/DC converter circuit, via an inverter circuit and outputs a torque to a drive shaft. In response to an estimated variation in road surface condition based on a decrease in angular acceleration of the drive shaft to be less than a threshold value ref during a slip, the control procedure of the invention adds a predetermined value to a torque upper limit Tmax, which is set at the time of the occurrence of the slip, and thereby updates the torque upper limit Tmax to start cancellation of torque restriction. The control procedure then updates the torque upper limit Tmax by a slope of a small time change to restrain the degree of cancellation of the torque restriction.

Abstract: In response to detection of a slip occurring on left and right front wheels (62a, 62b) caused by spin of one of the left and right front wheels (62a, 62b), the control technique of the invention restricts a torque output from a motor (22)to a drive shaft (28), while activating a hydraulic brake (54a) or (54b) corresponding to the spinning wheel to output a brake torque, so as to distribute the output torque of the motor (22) practically equally into the left and right front wheels (62a, 62b). This arrangement desirably improves the starting performance and the accelerating performance of a vehicle with the left and right front wheels (62a, 62b) running on the road surface of different frictional coefficients.

Abstract: When a computed torque command value Tr* of a ring gear shaft as a drive shaft exceeds a maximum torque Tmax, skid occurring state control (step S118) triggered by detection of the occurrence of a skid calculates a torque restriction rate KT (=Tmax/Tr*) and restricts the torque output to the ring gear shaft to a maximum torque Tmax. In a next cycle of a drive control routine, a power demand Pr, which is calculated from inputs of accelerator pedal position AP and vehicle speed V at step S105, is limited to the product of the power demand Pr and a power restriction rate KP (=KT) at step S107. The control with the limited power demand Pr desirably prevents a large engine noise beyond the driver's expectation based on the vehicle driving state.

Abstract: Under the condition of a large variation Tm in motor torque demand Tm*, the significant torque change may lead to some vibration of a vehicle to temporarily heighten an angular acceleration. The temporary rise of the angular acceleration may cause the angular acceleration to exceed a preset threshold value slip and result in misdetection of the occurrence of a ‘phantom’ skid in an angular acceleration—based skid state determination (step S112). The drive control of the invention accordingly specifies a potential for misdetection of the occurrence of a ‘phantom’ skid when the variation Tm in motor torque demand Tm* exceeds a preset threshold value Tthr at step S108. The drive control thereby does not execute skid occurring state control (step S120) with torque restriction but performs grip state control at step S116.

Abstract: Under the condition of a large variation ?Tm in motor torque demand Tm*, the significant torque change may lead to some vibration of a vehicle to temporarily heighten an angular acceleration ?. The temporary rise of the angular acceleration ? may cause the angular acceleration ? to exceed a preset threshold value ?slip and result in misdetection of the occurrence of a ‘phantom’ skid in an angular acceleration ?-based skid state determination (step S112). The drive control of the invention accordingly specifies a potential for misdetection of the occurrence of a ‘phantom’ skid when the variation ?Tm in motor torque demand Tm* exceeds a preset threshold value Tthr at step S108. The drive control thereby does not execute skid occurring state control (step S120) with torque restriction but performs grip state control at step S116.

Abstract: In response to detection of a skid of drive wheels based on an increase in angular acceleration ? of a rotating shaft of a motor, the control procedure of the invention refers to a map representing a variation in maximum torque Tmax against the angular acceleration ? and sets torque restriction of the motor to limit the torque level of the motor to the maximum torque Tmax corresponding to a peak value of the angular acceleration ?. When the torque restriction sufficiently lowers the angular acceleration ? to detect convergence of the skid, the control procedure cancels the torque restriction to a certain level of the maximum torque Tmax corresponding to a torque restoration limit ?1, which is set according to the degree of the skid. The torque restoration limit ?1 (that is, the maximum torque Tmax) is cancelled in a stepwise manner by a cancellation rate and a cancellation time corresponding to an additional accelerator depression relative to an accelerator opening at the time of detection of the skid.

Abstract: An increase in angular acceleration ? of a rotating shaft of a motor, which outputs a torque to a drive shaft linked to drive wheels, may cause a skid on the drive wheels. In response to detection of a skid, the control procedure of the invention sets a maximum torque Tmax according to a preset map representing a relation between the angular acceleration ? and the maximum torque Tmax, and restricts an output torque level to the drive shaft. The map is set to decrease the maximum torque Tmax with an in crease in angular acceleration ?. The restricted output torque level is restored at a zero cross timing of the angular acceleration ? after a negative peak in the course of convergence of the skid. This arrangement makes the direction of the torque restored from the torque restriction identical with the direction of the angular acceleration, thus effectively reducing torsions of the drive shaft and thereby preventing potential torsional vibrations of the drive shaft.

Abstract: A vehicle is equipped with a motor that receives a supply of electric power, which is output from a battery and is boosted up by a DC/DC converter circuit, via an inverter circuit and outputs a torque to a drive shaft. In response to an estimated variation in road surface condition based on a decrease in angular acceleration of the drive shaft to be less than a threshold value ref during a slip, the control procedure of the invention adds a predetermined value to a torque upper limit Tmax, which is set at the time of the occurrence of the slip, and thereby updates the torque upper limit Tmax to start cancellation of torque restriction. The control procedure then updates the torque upper limit Tmax by a slope of a small time change to restrain the degree of cancellation of the torque restriction.

Abstract: In response to detection of a slip-down of a vehicle under restriction of a motor torque Tm*, which is required for a drive shaft linked with drive wheels, due to the occurrence of a slip caused by spin of the drive wheels on an ending slope, the technique of the invention multiplies a torque insufficiency by a ratio (reflection ratio ?) specified according to a vehicle speed V in a t direction, so as to set a brake tourgue Tb*. The torque insufficiency corresponds to a difference between the restricted motor torque Tm* and a balancing torque Tgrad corresponding to a road surface gradient set according to the relation between an acceleration of the vehicle and a torque output to the drive shaft The setting of the brake torque Tb makes the velocity of the slip-down of the vehicle approach to a preset vehicle speed. The brake torque Tb* is applied by hydraulic brakes attached to driven wheels which am different from the drive wheels.

Abstract: In response to detection of a slip occurring on left and right front wheels (62a, 62b) caused by spin of one of the left and right front wheels (62a, 62b), the control technique of the invention restricts a torque output from a motor (22) to a drive shaft (28), while activating a hydraulic brake (54a) or (54b) corresponding to the spinning wheel to output a brake torque, so as to distribute the output torque of the motor (22) practically equally into the left and right front wheels (62a, 62b). This arrangement desirably improves the starting performance and the accelerating performance of a vehicle with the left and right front wheels (62a, 62b) running on the road surface of different frictional coefficients.

Abstract: When an angular acceleration ? of a rotating shaft of a motor connected with a drive shaft exceeds a preset threshold value ?slip, which suggests the occurrence of a skid, the torque control procedure sets a maximum torque Tmax by referring to a map, which gives a smaller maximum torque Tmax with an increase in angular acceleration ?, and restricts the motor torque to the maximum torque Tmax. The maximum torque Tmax is fixed to a value corresponding to a peak value of the angular acceleration ? at the time of occurrence of a skid. The torque control procedure then integrates the angular acceleration ? to give a time integration thereof over an integration interval when the angular acceleration ? once exceeds the preset threshold value ?slip and decreases again below the preset threshold value ?slip by the motor torque restriction.

Abstract: An increase in angular acceleration ? of a rotating shaft of a motor, which outputs a torque to a drive shaft linked to drive wheels, may cause a skid on the drive wheels. In response to detection of a skid, the control procedure of the invention sets a maximum torque Tmax according to a preset map representing a relation between the angular acceleration ? and the maximum torque Tmax, and restricts an output torque level to the drive shaft. The map is set to decrease the maximum torque Tmax with an in crease in angular acceleration ?. The restricted output torque level is restored at a zero cross timing of the angular acceleration ? after a negative peak in the course of convergence of the skid. This arrangement makes the direction of the torque restored from the torque restriction identical with the direction of the angular acceleration, thus effectively reducing torsions of the drive shaft and thereby preventing potential torsional vibrations of the drive shaft.

Abstract: In response to detection of a skid of drive wheels based on an increase in angular acceleration ? of a rotating shaft of a motor, the control procedure of the invention refers to a map representing a variation in maximum torque Tmax against the angular acceleration ? and sets torque restriction of the motor to limit the torque level of the motor to the maximum torque Tmax corresponding to a peak value of the angular acceleration ?. When the torque restriction sufficiently lowers the angular acceleration ? to detect convergence of the skid, the control procedure cancels the torque restriction to a certain level of the maximum torque Tmax corresponding to a torque restoration limit ?1, which is set according to the degree of the skid. The torque restoration limit ?1 (that is, the maximum torque Tmax) is cancelled in a stepwise manner by a cancellation rate and a cancellation time corresponding to an additional accelerator depression relative to an accelerator opening at the time of detection of the skid.

Abstract: Under the condition of a large variation Tm in motor torque demand Tm*, the significant torque change may lead to some vibration of a vehicle to temporarily heighten an angular acceleration. The temporary rise of the angular acceleration may cause the angular acceleration to exceed a preset threshold value slip and result in misdetection of the occurrence of a ‘phantom’ skid in an angular acceleration—based skid state determination (step S112). The drive control of the invention accordingly specifies a potential for misdetection of the occurrence of a ‘phantom’ skid when the variation Tm in motor torque demand Tm* exceeds a preset threshold value Tthr at step S108. The drive control thereby does not execute skid occurring state control (step S120) with torque restriction but performs grip state control at step S116.

Abstract: When an angular acceleration ? of a rotating shaft of a motor connected with a drive shaft exceeds a preset threshold value ?slip, which suggests the occurrence of a skid, the torque control procedure sets a maximum torque Tmax by referring to a map, which gives a smaller maximum torque Tmax with an increase in angular acceleration ?, and restricts the motor torque to the maximum torque Tmax. The maximum torque Tmax is fixed to a value corresponding to a peak value of the angular acceleration ? at the time of occurrence of a skid. The torque control procedure then integrates the angular acceleration ? to give a time integration thereof over an integration interval when the angular acceleration ? once exceeds the preset threshold value ?slip and decreases again below the preset threshold value ?slip by the motor torque restriction.

Abstract: When a computed torque command value Tr* of a ring gear shaft as a drive shaft exceeds a maximum torque Tmax, skid occurring state control (step S118) triggered by detection of the occurrence of a skid calculates a torque restriction rate KT (=Tmax/Tr*) and restricts the torque output to the ring gear shaft to a maximum torque Tmax. In a next cycle of a drive control routine, a power demand Pr, which is calculated from inputs of accelerator pedal position AP and vehicle speed V at step S105, is limited to the product of the power demand Pr and a power restriction rate KP (=KT) at step S107. The control with the limited power demand Pr desirably prevents a large engine noise beyond the driver's expectation based on the vehicle driving state.

Abstract: The control procedure of the invention sets the measured value of the rotation angular acceleration ? to a first peak angular acceleration ?1 at a timing when the rotation angular acceleration ? of a motor, which directly outputs torque to a drive shaft, reaches a first peak after an increase over a preset threshold value ?slip that suggests the occurrence of a wheelspin-induced skid. The control procedure also sets a second peak angular acceleration ?2 by multiplication of the measured value of the rotation angular acceleration ? by ‘?1’ at a timing when the rotation angular acceleration ? reaches a negative second peak detected immediately after the first peak.