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Apparatus and method for stability controlling vehicular attitude using vehicular braking system

  • US 5,893,896 A
  • Filed: 05/30/1997
  • Issued: 04/13/1999
  • Est. Priority Date: 05/31/1996
  • Status: Expired due to Term
First Claim
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1. An apparatus for a vehicle, comprising:

  • a braking system having a master cylinder, a plurality of wheel cylinders, each of the wheel cylinders being arranged around a corresponding one of front left and right road wheels and rear left and right road wheels so as to apply a braking force to the corresponding one of the front left and right and rear left and right road wheels according to a braking liquid pressure supplied thereto, and two separate braking liquid pressure distribution conduits which are so arranged and constructed as to distribute the braking liquid pressure developed in the master cylinder according to a brake demand to the wheel cylinders arranged around the front right and the rear left road wheels and to the wheel cylinders arranged around the front left and rear right road wheels, respectively;

    a control purpose liquid pressure source which is so arranged and constructed as to enable an increase in the liquid pressure applied to each wheel cylinder independently of the liquid pressure in the master cylinder developed according to the brake demand;

    a selector which is so arranged and constructed as to selectively output a liquid pressure supply to the respective wheel cylinders from either the master cylinder or the control purpose liquid pressure source;

    a vehicular behavior detector which is so arranged and constructed as to detect a vehicular behavior; and

    a controller, having a first determinator determining whether an oversteer of the vehicle exceeding a predetermined magnitude occurs on the basis of an inputted signal indicating the vehicular behavior from the vehicular behavior detector, said controller carrying out an oversteer avoidance control via the selector such that the liquid pressure in the control purpose liquid pressure source is supplied to one of the braking pressure distribution conduits through which a braking force is applied to one of the front road wheels via the corresponding one of the wheel cylinders in a direction toward which a yaw moment is suppressed and the liquid pressure in the master cylinder is supplied to the other of the braking pressure distribution conduits, when the first determinator determines that the oversteer of the vehicle exceeding the predetermined magnitude occurs, wherein the controller further comprises a second determinator arranged for determining whether an understeer of the vehicle exceeding a predetermined magnitude of the understeer occurs on the basis of the inputted signal from the vehicular behavior detector, the controller carrying out an understeer avoidance control via the selector such that the liquid pressure in the control purpose liquid pressure source is supplied to one of the braking liquid pressure distribution conduits through which the braking force is applied to one of the rear road wheels in a direction toward which the yaw moment is developed and the liquid pressure in the master cylinder is supplied to the other of the braking pressure distribution conduits, when the second determinator determines that the understeer of the vehicle exceeding the predetermined magnitude occurs, wherein said selector comprises first interrupting valves, interposed between the control purpose liquid pressure source and each of the two braking pressure distribution conduits, which is enabled to interrupt the supply of the liquid pressure in the control purpose liquid pressure source to the corresponding one of the two braking pressure distribution conduits, and second interrupting valves, interposed between the master cylinder and each of the two braking pressure distribution conduits, which is enabled to interrupt the supply of the liquid pressure in the master cylinder to the corresponding one of the two braking pressure distribution conduits and wherein said controller opens or closes each of the first and second interrupting valves during the oversteer or understeer avoidance control, wherein the vehicular behavior detector detects a yaw rate of the vehicle and wherein the first determinator determines whether the oversteer of the vehicle exceeding the predetermined magnitude occurs on the basis of the yaw rate and the second determinator determines whether the understeer of the vehicle occurs on the basis of the yaw rate, and wherein said controller further comprises a third determinator arranged for determining a slip angle of the vehicle on the basis of at least the yaw rate and wherein said first determinator determines whether the oversteer of the vehicle exceeding the predetermined magnitude occurs on the basis of the slip angle of the vehicle and said second determinator determined whether the understeer of the vehicle exceeding the predetermined magnitude occurs on the basis of the slip angle of the vehicle.

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