Automotive yaw-sensitive brake control system
First Claim
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1. A brake control system for a wheeled vehicle comprising:
- a first hydraulic brake circuit for applying braking pressure to vehicular front wheels, said first hydraulic circuit including a first braking pressure controlling actuator which operates to increase said braking pressure in a first position, to hold the braking pressure constant in a second position and to decrease the braking pressure in a third position;
a second hydraulic brake circuit for applying braking pressure to vehicular rear wheels, said second hydraulic circuit including a second braking pressure controlling actuator which operates to increase said braking pressure in a first position, to hold the braking pressure constant in a second position and to decrease the braking pressure in a third position;
a first sensor for producing a first sensor signal when the vehicle brakes are applied;
a second sensor for producing a second sensor signal having a value representative of the forces applied in the transverse direction to the vehicle;
a third sensor for producing a third sensor signal having a value representative of a vehicle driving condition, said vehicle driving condition being at least one of a vehicle speed and a steering angle; and
a controller for controlling said first and second actuators independently of each other, said controller deriving a vehicle driving stability factor in response to said first sensor signal and as a function of said second and third sensor signal values and controlling said first and second actuators to one of said first, second and third positions so as to hold said vehicle driving stability factor at a given value.
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Abstract
Automotive brake control is performed by controlling brake pressure at front and rear wheels independently. The braking force at each of the front and rear wheels is controlled in accordance with monitored vehicle driving conditions so that the steering characteristics of the vehicle are held to predetermined characteristics even when vehicular brakes are applied during cornering. The braking pressure at front wheels is decreased when understeer characteristics increases due to braking. On the other hand, the braking pressure at the rear wheel is decreased when oversteer characteristics increases due to braking.
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Citations
29 Claims
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1. A brake control system for a wheeled vehicle comprising:
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a first hydraulic brake circuit for applying braking pressure to vehicular front wheels, said first hydraulic circuit including a first braking pressure controlling actuator which operates to increase said braking pressure in a first position, to hold the braking pressure constant in a second position and to decrease the braking pressure in a third position; a second hydraulic brake circuit for applying braking pressure to vehicular rear wheels, said second hydraulic circuit including a second braking pressure controlling actuator which operates to increase said braking pressure in a first position, to hold the braking pressure constant in a second position and to decrease the braking pressure in a third position; a first sensor for producing a first sensor signal when the vehicle brakes are applied; a second sensor for producing a second sensor signal having a value representative of the forces applied in the transverse direction to the vehicle; a third sensor for producing a third sensor signal having a value representative of a vehicle driving condition, said vehicle driving condition being at least one of a vehicle speed and a steering angle; and a controller for controlling said first and second actuators independently of each other, said controller deriving a vehicle driving stability factor in response to said first sensor signal and as a function of said second and third sensor signal values and controlling said first and second actuators to one of said first, second and third positions so as to hold said vehicle driving stability factor at a given value. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. In an automotive vehicle having a brake system which includes a first brake circuit for applying braking pressure to front wheels, a second brake circuit for applying braking force to rear wheels and a steering system, a method for controlling steering characteristics to coincide with desired characteristics comprising the steps of:
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monitoring vehicle driving conditions including whether or not vehicular brakes have been applied; deriving a steering characteristics coefficient on the basis of the monitored driving conditions; monitoring variation of the steering characteristics coefficient while vehicular brakes are applied to decelerate the vehicle; deriving a first and second threshold value on the basis of said vehicle driving conditions and said steering characteristics coefficient; comparing said steering characteristics coefficient with said first threshold value and controlling said first brake circuit so as to adjust braking pressure applied to said front wheels in such a manner that a difference of said steering characteristics coefficient and said first threshold value is maintained within a predetermined range for optimizing braking characteristics at said front wheels; and comparing said steering characteristics coefficient with said second threshold value and controlling said second brake circuit so as to adjust braking pressure applied to said rear wheels in such a manner that a difference of said steering characteristics coefficient and said second threshold is maintained within a given range for optimizing braking characteristics at said rear wheels. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23, 24)
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25. A brake control system for a wheeled vehicle comprising:
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a first hydraulic brake circuit for applying braking pressure to vehicular front wheels, said first hydraulic circuit including a first braking pressure controlling actuator which operates to increase said braking pressure in a first position, to hold the braking pressure constant in a second position and to decrease the braking pressure in a third position; a second hydraulic brake circuit for applying braking pressure to vehicular rear wheels, said second hydraulic circuit including a second braking pressure controlling actuator which operates to increase said braking pressure in a first position, to hold the braking pressure constant in a second position and to decrease the braking pressure in a third position; a first sensor for producing a first sensor signal when the vehicle brakes are applied; a second sensor for producing a second sensor signal having a value representative of the forces applied in the transverse direction of the vehicle; a controller for controlling said first and second actuators independently of each other, said controller deriving a vehicle driving stability factor from said first and second sensor signal value and controlling said first and second actuators to one of said first, second and third positions so as to hold said vehicle driving stability factor at a given value.
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26. A brake control system for a wheeled vehicle comprising:
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a first hydraulic brake circuit for applying braking pressure to vehicular front wheels, said first hydraulic circuit including a first braking pressure controlling actuator which operates to increase said braking pressure in a first position, and to decrease the braking pressure in a second position; a second hydraulic brake circuit for applying braking pressure to vehicular rear wheels, said second hydraulic circuit including a second braking pressure controlling actuator which operates to increase said braking pressure in a first position and to decrease the braking pressure in a second position; a first sensor for producing a first sensor signal when the vehicle brakes are applied; a second sensor for producing a second sensor signal having a value representative of the forces applied in the transverse direction of the vehicle; a controller for controlling said first and second actuators independently of each other, said controller deriving a vehicle driving stability factor from said first and second sensor signal value and controlling said first and second actuators to one of said first and second positions so as to hold said vehicle driving stability factor at a given value.
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27. An automative vehicle having a brake system which includes a first brake circuit for applying braking pressure to front wheels, a second brake circuit for applying braking force to rear wheels and a steering system, a method for controlling steering characteristics to coincidence with desired characteristics comprising the steps of:
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monitoring vehicle driving condition including whether or not vehicular brakes have been applied; deriving a steering characteristics coefficient on the basis of the monitored driving conditions; monitoring variations of the steering characteristics coefficient while vehicular brakes are applied to decelerate the vehicle; deriving a first and second threshold value on the basis of said vehicular driving conditions and said steering characteristics coefficient; comparing said steering characteristics coefficient with said first threshold value and controlling said first brake circuit so as to adjust braking pressure to applied to said front wheel in such a manner that a difference of said steering characteristics coefficient and said first threshold is maintained within a predetermined range for optimizing braking characteristics at said front wheel; and comparing said steering characteristics coefficient with said second threshold value and controlling said second brake circuit so as to adjust braking pressure to applied to said rear wheel in such a manner that a difference of said steering characteristics coefficient and said second threshold is maintained within a given range for optimizing braking characteristics at said rear wheel.
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28. A brake control system for a wheeled vehicle comprising:
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a first hydraulic brake circuit for applying pressure to vehicular front wheel, said first hydraulic circuit including a first braking pressure controlling actuator which operates to increase said braking pressure in a first position, and to decrease the braking pressure in a second position; a second hydraulic brake circuit for applying braking pressure to vehicular rear wheel, said second hydraulic circuit including a second braking pressure controlling actuator which operates to increase said braking pressure in a first position and to decrease the braking pressure in a second position; a first sensor for producing a first sensor signal when the vehicle brake are applied; a second sensor for producing a second sensor signal having a value representative of the forces applied in the transverse direction of the vehicle; a controller for controlling said first and second actuators independently of each other, said controller deriving a vehicle driving stability factor from said first sensor signal and said second sensor signal value and controlling said first and second actuators to one of said first and second position so as to hold said vehicle cornering stability factor at a desired optimum level.
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29. A brake control system for a wheeled vehicle comprising:
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a first hydraulic brake circuit for applying braking pressure to vehicular front wheels, said first hydraulic circuit including a first braking pressure controlling actuator which operates to increase said braking pressure in a first position, and to decrease the braking pressure in a second position; a second hydraulic brake circuit for applying braking pressure to vehicular rear wheels, said second hydraulic circuit including a second braking pressure controlling actuator which operates to increase said braking pressure in a first position and to decrease the braking pressure in a second position; a first sensor for producing a first sensor signal when the vehicle brakes are applied; a second sensor for producing a second sensor signal having a value representative of the forces applied in the transverse direction of the vehicle; a controller for controlling said first and second actuators independently of each other, said controller deriving a vehicle driving stability factor which is representative of a target yawing rate to be exerted on the vehicle, on the basis of said first sensor signal value and said second sensor signal value and controlling said first and second actuators to one of said first and second positions so as to hold the yawing rate to be exerted on the vehicle at said target yawing rate for maintaining vehicular cornering stability at a desired optimum level.
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Specification