Anti-skid brake control system for automotive vehicle with a feature variable wheel slippage threshold variable depending upon vehicular lateral force

Claim 2

An anti-skid brake control system for an automotive vehicle comprising: a hydraulic brake circuit for building up braking fluid pressure according to manual braking operation and distributing fluid pressure to at least one wheel cylinder; a pressure control valve unit disposed within said hydraulic brake circuit for varying valve positions between a first position in which fluid pressure in the wheel cylinder is increased according to the increase in said braking pressure built up in said hydraulic brake circuit, and a second position in which said fluid pressure in said wheel cylinder is decreased; a first sensor for producing a wheel speed indicative signal representative of a rotation speed of a vehicular wheel; a second sensor for producing a lateral force indicative signal representative of a lateral force applied to a vehicle body; a controller receiving said wheel speed indicative signal for deriving a control signal for operating said pressure control valve unit between said first and second positions, said controller deriving a wheel slippage based on said wheel speed and comparing derived wheel slippage with a given reference value so as to operate said pressure valve to said second position when the derived wheel slippage is greater than said given reference value, said controller being further operable for deriving said given reference value on the basis of the magnitude of the lateral force exerted on the vehicle body for adjusting said given reference value depending upon the lateral force magnitude, said controller comparing said lateral force indicative signal value with a given threshold representative of a lateral force criterion and responsive to said lateral force indicative signal having a value greater than said given threshold for decreasing said given reference value.

Claim 3

An anti-skid brake control system as set forth in claim 1, wherein said second sensor comprises a yaw rate sensor for monitoring magnitude of yawing motion of the vehicle and producing a yawing rate indicative signal serving as said lateral force indicative signal.

Claim 4

An anti-skid brake control system as set forth in claim 1, wherein said second sensor comprises a steering angle sensor for monitoring steering angular variation and producing a steering angle indicative signal serving as said lateral force indicative signal.

Claim 5

An anti-skid brake control system as set forth in claim 3, wherein said second sensor further includes a yaw rate sensor for monitoring the magnitude of yawing motion of the vehicle and producing a yawing rate indicative signal serving as said lateral force indicative signal.

Claim 6

An anti-skid brake control system for an automotive brake system comprising: a hydraulic brake system including a wheel cylinder for applying braking pressure to a vehicle wheel, and a pressure control valve associated with said wheel cylinder for adjusting fluid pressure in the wheel cylinder, said pressure control valve being operative to increase fluid pressure in said wheel cylinder in a first position, to decrease fluid pressure in said wheel cylinder in a second position and to hold fluid pressure in said wheel cylinder constant in a third position; a wheel speed sensor detecting rotation speed indicative signal having a value indicative of the detected wheel speed; a lateral force sensor for producing a lateral force indicative signal representative of a lateral force applied to a vehicle body; a controller deriving a control signal for controlling operation of said pressure control valve to actuate the latter to one of said first, second and third position on the basis of said wheel speed indicative signal so as to control wheel speed in a given optimal relationship with vehicle speed, said controller deriving a wheel slippage based on said wheel speed and comparing derived wheel slippage with a given reference value which is representative of a predetermined wheel slippage criterion so as to operate said pressure control valve to said second position when the derived wheel slippage is greater than said given reference value, and said controller being further operable for deriving said given reference value on the basis of the magnitude of the lateral force exerted on the vehicle body for adjusting said given reference value depending upon the lateral force magnitude, said controller comparing said lateral force indicative signal value with a given threshold representative of a lateral force criterion and responsive to said lateral force indicative signal having a value greater than said given threshold for decreasing said given reference value.

Claim 7

An anti-skid brake control system for an automotive brake system comprising: a hydraulic brake system including a wheel cylinder for applying braking pressure to a vehicle wheel, and a pressure control valve associated with said wheel cylinder for adjusting fluid pressure in the wheel cylinder, said pressure control valve being operative to increase fluid pressure in said wheel cylinder in a first position, to decrease fluid pressure in said wheel cylinder in a second position and to hold fluid pressure in said wheel cylinder constant in a third position; a wheel speed sensor detecting rotation speed indicative signal having a value indicative of the detected wheel speed; a lateral force sensor for producing a lateral force indicative signal representative of a lateral force applied to a vehicle body; a controller deriving a control signal for controlling operation of said pressure control valve to actuate the latter to one of said first, second and third position on the basis of said wheel speed indicative signal so as to control wheel speed in a given optimal relationship with vehicle speed, said controller deriving a wheel slippage based on said wheel speed and comparing derived wheel slippage with a given reference value which is representative of a predetermined wheel slippage criterion so as to operate said pressure control valve to said second position when the derived wheel slippage is greater than said given reference value, and said controller being further operable for deriving said given reference value on the basis of the magnitude of the lateral force exerted on the vehicle body for adjusting said given reference value depending upon the lateral force magnitude, said controller comparing said lateral force indicative signal value with a given threshold representative of a lateral force criterion and responsive to said lateral force indicative signal having a value greater than said given threshold for decreasing said given reference value.

Claim 8

An anti-skid brake control system for an automotive brake system comprising: a hydraulic brake system including a wheel cylinder for applying braking pressure to a vehicle wheel, and a pressure control valve associated with said wheel cylinder for adjusting fluid pressure in the wheel cylinder, said pressure control valve being operative to increase fluid pressure in said wheel cylinder in a first position, to decrease fluid pressure in said wheel cylinder in a second position and to hold fluid pressure in said wheel cylinder constant in a third position; a wheel speed sensor detecting rotation speed indicative signal having a value indicative of the detected wheel speed; a lateral force sensor for producing a lateral force indicative signal representative of a lateral force applied to a vehicle body; a controller deriving a control signal for controlling operation of said pressure control valve to actuate the latter to one of said first, second and third position on the basis of said wheel speed indicative signal so as to control wheel speed in a given optimal relationship with vehicle speed, said controller deriving a wheel slippage based on said wheel speed and comparing derived wheel slippage with a given reference value said controller is operative to derive brake control parameters including a wheel acceleration and said wheel slippage and to derive the control signal according to a predetermined schedule in which: said pressure control valve is actuated to said third position when the derived wheel deceleration is greater than a given deceleration threshold, in a hold mode of said controller; said pressure control valve is actuated to said second position when the derived slip rate is greater than a given slip rate threshold, in a released mode of said controller; said pressure control valve is actuated to said third position when said slip rate is less than said slip rate threshold, in a hold mode of said controller; and said pressure control valve is actuated to said first position when the derived wheel acceleration is greater than a given acceleration threshold, to said third position when the fluid pressure increased due to the pressure control valve being in said first position, reaches a given pressure slightly below the lock pressure, and to said first position after expiration of said given period, in an application mode of the controller, and said controller being further active to operate said pressure control valve to said second position when the derived wheel slippage is greater than said given reference value, and said controller being responsive to said lateral force indicative signal having a value exceeding a given threshold for decreasing said given reference value at a predetermined value.

Claim 9

An anti-skid brake control system for an automotive brake system comprising: a hydraulic brake system including a wheel cylinder for applying braking pressure to a vehicle wheel, and a pressure control valve associated with said wheel cylinder for adjusting fluid pressure in the wheel cylinder, said pressure control valve being operative to increase fluid pressure in said wheel cylinder in a first position, to decrease fluid pressure in said wheel cylinder in a second position and to hold fluid pressure in said wheel cylinder constant in a third position; a wheel speed sensor detecting rotation speed indicative signal having a value indicative of the detected wheel speed; a lateral force sensor for producing a lateral force indicative signal representative of a lateral force applied to a vehicle body; a controller deriving a control signal for controlling operation of said pressure control valve to actuate the latter to one of said first, second and third position on the basis of said wheel speed indicative signal so as to control wheel speed in a given optimal relationship with vehicle speed, said controller deriving a wheel slippage based on said wheel speed and comparing derived wheel slippage with a given reference value said controller is operative to derive brake control parameters including a wheel acceleration and said wheel slippage and to derive the control signal according to a predetermined schedule in which: said pressure control valve is actuated to said third position when the derived wheel deceleration is greater than a given deceleration threshold, in a hold mode of said controller; said pressure control valve is actuated to said second position when the derived slip rate is greater than a given slip rate threshold, in a released mode of said controller; said pressure control valve is actuated to said third position when said slip rate is less than said slip rate threshold, in a hold mode of said controller; and said pressure control valve is actuated to said first position when the derived wheel acceleration is greater than a given acceleration threshold, to said third position when the fluid pressure increased due to the pressure control valve being in said first position, reaches a given pressure slightly below the lock pressure, and to said first position after expiration of said given period, in an application mode of the controller, and said controller being further active to operate said pressure control valve to said second position when the derived wheel slippage is greater than said given reference value, and said controller being responsive to said lateral force indicative signal having a value exceeding a given threshold for decreasing said given reference value at a predetermined value.

Claim 10

An anti-skid brake control system as set forth in claim 6, wherein said lateral force sensor comprises a yaw rate sensor for monitoring magnitude of yawing motion of the vehicle and producing a yawing rate indicative signal serving as said lateral force indicative signal.

Claim 11

An anti-skid brake control system as set forth in claim 6, wherein said lateral force sensor comprises a steering angle sensor for monitoring steering angular variation and producing a steering angle indicative signal serving as said lateral force indicative signal.

Claim 12

An anti-skid brake control system as set forth in claim 8, wherein said lateral force sensor further includes a yaw rate sensor for monitoring magnitude of yawing motion of the vehicle and producing a yawing rate indicative signal serving as said lateral force indicative signal.

Claim 13

An anti-skid brake control system for an automotive vehicle comprising: a hydraulic brake circuit for building up braking fluid pressure according to manual braking operation and distributing fluid pressure to at least one wheel cylinder; a pressure control valve unit disposed within said hydraulic brake circuit for varying valve positions between a first position in which fluid pressure in the wheel cylinder is increased according to the increase in said braking pressure built up in said hydraulic brake circuit, and a second position in which said fluid pressure in said wheel cylinder is decreased; a first sensor for producing a wheel speed indicative signal representative of a rotation speed of a vehicular wheel; a second sensor for producing a lateral force indicative signal representative of a lateral force applied to a vehicle body; a controller receiving said wheel speed indicative signal for deriving a control signal for operating said pressure control valve unit between said first and second positions, said controller deriving a wheel slippage based on said wheel speed and comparing derived wheel slippage with a given reference value, said controller activating said pressure control valve to said first position when the derived wheel acceleration is greater than a given acceleration threshold, to said third position when the fluid pressure is increased due to the pressure control valve being in said first position, reaches a given pressure slightly below the lock pressure, and to said first position after expiration of said given period, in an application mode of the controller, to operate said pressure valve to said second position when the derived wheel slippage is greater than said given reference value, said controller being further operable for deriving said given reference value on the basis of the magnitude of the lateral force exerted on the vehicle body for adjusting said given reference value depending upon the lateral force magnitude, said controller comparing said lateral force indicative signal value with a given threshold representative of a lateral force criterion and responsive to said lateral force indicative signal having a value greater than said given threshold for decreasing said given reference value.

Claim 14

An anti-skid brake control system for an automotive vehicle comprising: a hydraulic brake circuit for building up braking fluid pressure according to manual braking operation and distributing fluid pressure to at least one wheel cylinder; a pressure control valve unit disposed within said hydraulic brake circuit for varying valve positions between a first position in which fluid pressure in the wheel cylinder is increased according to the increase in said braking pressure built up in said hydraulic brake circuit, and a second position in which said fluid pressure in said wheel cylinder is decreased; a first sensor for producing a wheel speed indicative signal representative of a rotation speed of a vehicular wheel; a second sensor for producing a lateral force indicative signal representative of a lateral force applied to a vehicle body; a controller receiving said wheel speed indicative signal for deriving a control signal for operating said pressure control valve unit between said first and second positions, said controller deriving a wheel slippage based on said wheel speed and comparing derived wheel slippage with a given reference value, said controller activating said pressure control valve to said first position when the derived wheel acceleration is greater than a given acceleration threshold, to said third position when the fluid pressure is increased due to the pressure control valve being in said first position, reaches a given pressure slightly below the lock pressure, and to said first position after expiration of said given period, in an application mode of the controller, to operate said pressure valve to said second position when the derived wheel slippage is greater than said given reference value, said controller being further operable for deriving said given reference value on the basis of the magnitude of the lateral force exerted on the vehicle body for adjusting said given reference value depending upon the lateral force magnitude, said controller comparing said lateral force indicative signal value with a given threshold representative of a lateral force criterion and responsive to said lateral force indicative signal having a value greater than said given threshold for decreasing said given reference value.