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Traction control system for a four-wheel drive motor vehicle

  • US 5,004,064 A
  • Filed: 10/20/1988
  • Issued: 04/02/1991
  • Est. Priority Date: 10/27/1987
  • Status: Expired due to Term
First Claim
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1. In a power transmitting system for a four-wheel drive vehicle having a central differential for splitting torque of an engine at a predetermined ratio, power trains for transmitting the split torques from output members of the central differential to front and rear wheels respectively of the vehicle, a throttle actuator for changing opening degree of a throttle valve of the engine, and a torque split control device including a clutch provided between the output members of the central differential for changing torque distribution ratio of the torques transmitted to the front and rear wheels, the improvement in the system comprising:

  • front-wheel speed sensors for detecting right and left front-wheel speeds and for producing right and left front-wheel sped signals;

    rear-wheel speed sensors for detecting right and left rear-wheel speeds and for producing right and left rear-wheel speed signals;

    first calculator means responsive to the right and left front-wheel and rear-wheel speed signals for producing a front-axle speed signal and a rear-axle speed signal;

    two-wheel slip detecting means responsive to the front-axle speed signal and the rear-axle speed signal for producing a two-wheel slip signal when the front wheels are slipping with respect to the rear wheels or the rear wheels are slipping with respect to the front wheels;

    four-wheel slip detecting means responsive to the front-axle and rear-axle speed signals and a vehicle body acceleration signal only at non-existence of the two-wheel slip signal for producing a four-wheel slip signal;

    actuator means responsive to the two-wheel slip signal for controlling engaging of the clutch controlling the torque distribution ratio so as to reduce the torque to the slipping wheels; and

    actuating means being responsive to the four-wheel slip signal for actuating the throttle actuator so as to reduce the opening degree of the throttle valve.

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