Anti-skid brake control system with feature of derivation of precise projected vehicle body speed data utilizing longitudinal acceleration exerted on vehicular body

Claim 2

An anti-skid brake control system comprising: a hydraulic circuit connecting a hydraulic pressure source to a wheel cylinder generating a braking pressure therein; a pressure control valve means disposed in said hydraulic circuit, for operating to increase said braking pressure in said wheel cylinder in a first mode and to decrease said braking pressure in said wheel cylinder in a second mode; a first sensor means for monitoring rotation speed of a vehicular wheel to which said wheel cylinder is associated to produce a wheel speed indicative signal; a second sensor means for monitoring a longitudinal acceleration exerted on a vehicle body for producing a longitudinal acceleration indicative signal; a first arithmetic means for providing a predetermined offset value to said longitudinal acceleration indicative signal and integrating the offset longitudinal acceleration indicative signal for deriving a wheel speed deceleration magnitude indicative data, and subtracting said wheel speed deceleration magnitude indicative data from an initial value which corresponds to a wheel speed indicative signal value at the beginning of each skid control cycle for deriving a vehicle body speed representative data; and a second arithmetic means for controlling said pressure control valve means in a first mode for placing said pressure control valve in said first position and in a second mode for placing said pressure control valve means in said second position, said second arithmetic means deriving a control signal for selecting said first and second mode on the basis of said wheel speed indicative signal and said vehicle body speed representative data so as to maintain a wheel slippage within a predetermined range.

Claim 3

An anti-skid brake control system as set forth in claim 1, wherein said first arithmetic means operates in a normal arithmetic mode for deriving said vehicle body speed representative data to a value corresponding to said wheel speed indicative signal value and a skid control state arithmetic mode for deriving said vehicle body speed on the basis of said initial value and said integrated value of said offset longitudinal acceleration indicative value in said skid cycle.

Claim 4

An anti-skid brake control system as set forth in claim 2, wherein said first means derives a wheel acceleration and compared said wheel acceleration with a predetermined threshold value so as to select said said normal arithmetic mode when said wheel acceleration is maintained greater than or equal to said threshold value and to select said skid control state arithmetic mode otherwise.

Claim 5

An anti-skid brake control system as set forth in claim 3, wherein said first means further compares said vehicle body speed representative data and said wheel speed indicative signal value so as to permit said normal arithmetic mode operation when said wheel speed indicative signal value is greater than or equal to said vehicle body speed representative data.

Claim 6

An anti-skid brake control system comprising: a hydraulic circuit connecting a hydraulic pressure source to a first and second wheel cylinders generating braking pressures for decelerating first and second vehicular wheels; first and second pressure control valve means disposed in said hydraulic circuit for controlling braking pressure generated in respectively associated one of first and second wheel cylinders, each of said first and second pressure control valve means operating to increase said braking pressure in said wheel cylinder in a first mode and to decrease said braking pressure in said wheel cylinder in a second mode; a first sensor means for monitoring rotation speed of said first vehicular wheel to which said first wheel cylinder is associated to produce a first wheel speed indicative signal; a second sensor means for monitoring rotation speed of said second vehicular wheel to which said second wheel cylinder is associated to produce a second wheel speed indicative signal; a third sensor means for monitoring a longitudinal acceleration exerted on a vehicle body for producing a longitudinal acceleration indicative signal; a first arithmetic means for providing a predetermined offset value to said longitudinal acceleration indicative signal and integrating the offset longitudinal acceleration indicative signal for deriving a wheel speed deceleration magnitude indicative data, and subtracting said wheel speed deceleration magnitude indicative data from an initial value which corresponds to the greater one of said first and second wheel speed indicative signal values at the beginning of each skid control cycle for deriving a vehicle body speed representative data; and a second arithmetic means for controlling said pressure control valve means in a first mode for placing said pressure control valve in said first position and in a second mode for placing said pressure control valve means in said second position, said second arithmetic means deriving a control signal for selecting said first and second mode on the basis of said wheel speed indicatiue signal and said vehicle body speed representative data so as to maintain a wheel slippage within a predetermined range.

Claim 7

An anti-skid brake control system comprising: a hydraulic circuit connecting a hydraulic pressure source to a first and second wheel cylinders generating braking pressures for decelerating first and second vehicular wheels; first and second pressure control valve means disposed in said hydraulic circuit for controlling braking pressure generated in respectively associated one of first and second wheel cylinders, each of said first and second pressure control valve means operating to increase said braking pressure in said wheel cylinder in a first mode and to decrease said braking pressure in said wheel cylinder in a second mode; a first sensor means for monitoring rotation speed of said first vehicular wheel to which said first wheel cylinder is associated to produce a first wheel speed indicative signal; a second sensor means for monitoring rotation speed of said second vehicular wheel to which said second wheel cylinder is associated to produce a second wheel speed indicative signal; a third sensor means for monitoring a longitudinal acceleration exerted on a vehicle body for producing a longitudinal acceleration indicative signal; a first arithmetic means for providing a predetermined offset value to said longitudinal acceleration indicative signal and integrating the offset longitudinal acceleration indicative signal for deriving a wheel speed deceleration magnitude indicative data, and subtracting said wheel speed deceleration magnitude indicative data from an initial value which corresponds to the greater one of said first and second wheel speed indicative signal values at the beginning of each skid control cycle for deriving a vehicle body speed representative data; and a second arithmetic means for controlling said pressure control valve means in a first mode for placing said pressure control valve in said first position and in a second mode for placing said pressure control valve means in said second position, said second arithmetic means deriving a control signal for selecting said first and second mode on the basis of said wheel speed indicatiue signal and said vehicle body speed representative data so as to maintain a wheel slippage within a predetermined range.

Claim 8

An anti-skid brake control system as set forth in claim 5, wherein said first arithmetic means operates in a normal arithmetic mode for deriving said vehicle body speed representative data to a value corresponding to said greater one of said first and second wheel speed indicative signal values and a skid control state arithmetic mode for deriving said vehicle body speed on the basis of said initial value and said integrated value of said offset longitudinal acceleration indicative value in said skid cycle.

Claim 9

An anti-skid brake control system as set forth in claim 6, wherein said first means derives a wheel acceleration and compared said wheel acceleration with a predetermined threshold value so as to select said said normal arithmetic mode when said wheel acceleration is maintained greater than or equal to said threshold value and to select said skid control state arithmetic mode otherwise.

Claim 10

An anti-skid brake control system as set forth in claim 7, wherein said first means further compares said vehicle body speed representative data and said wheel speed indicative signal value so as to permit said normal arithmetic mode operation when said wheel speed indicative signal value is greater than or equal to said vehicle body speed representative data.

Claim 11

An anti-skid brake control system comprising: a hydraulic circuit connecting a hydraulic pressure source to at least first, second and third wheel cylinders generating braking pressures for decelerating first, second and third vehicular wheels; at least first, second and third pressure control valve means disposed in said hydraulic circuit for controlling braking pressures generated in respectively associated one of first, second and third wheel cylinders, each of said first, second and third pressure control valve means operating to increase said braking pressure in the associated one of said first, second and third wheel cylinders in a first mode, to decrease said braking pressure in said wheel cylinder in a second mode and to hold the braking pressure in said wheel cylinder at a constant value in a third mode; a first sensor means for monitoring rotation speed of said first vehicular wheel to which said first wheel cylinder is associated to produce a first wheel speed indicative signal; a second sensor means for monitoring rotation speed of said second vehicular wheel to which said second wheel cylinder is associated to produce a second wheel speed indicative signal; a third sensor means for monitoring rotation speed of said third vehicular wheel to which said third wheel cylinder is associated to produce a third wheel speed indicative signal; a fourth sensor means for monitoring a longitudinal acceleration exerted on a vehicle body for producing a longitudinal acceleration indicative signal; a first arithmetic means for providing a predetermined offset value to said longitudinal acceleration indicative signal and integrating the offset longitudinal acceleration indicative signal for deriving a wheel speed deceleration magnitude indicative data, and subtracting said wheel speed deceleration magnitude indicative data from an initial value which corresponds to one of said first, second and third wheel speed indicative signal values having the greatest value at the beginning of each skid control cycle for deriving a vehicle body speed representative data; and a second arithmetic means for controlling said pressure control valve means in a first mode for placing said pressure control valve in said first position, in a second mode for placing said pressure control valve means in said second position in a third mode for placing said pressure control valve means to said third position, said second arithmetic means deriving a control signal for selecting said first and second mode on the basis of said wheel speed indicative signal and said vehicle body speed representative data so as to maintain a wheel slippage within a predetermined range.

Claim 12

An anti-skid brake control system comprising: a hydraulic circuit connecting a hydraulic pressure source to at least first, second and third wheel cylinders generating braking pressures for decelerating first, second and third vehicular wheels; at least first, second and third pressure control valve means disposed in said hydraulic circuit for controlling braking pressures generated in respectively associated one of first, second and third wheel cylinders, each of said first, second and third pressure control valve means operating to increase said braking pressure in the associated one of said first, second and third wheel cylinders in a first mode, to decrease said braking pressure in said wheel cylinder in a second mode and to hold the braking pressure in said wheel cylinder at a constant value in a third mode; a first sensor means for monitoring rotation speed of said first vehicular wheel to which said first wheel cylinder is associated to produce a first wheel speed indicative signal; a second sensor means for monitoring rotation speed of said second vehicular wheel to which said second wheel cylinder is associated to produce a second wheel speed indicative signal; a third sensor means for monitoring rotation speed of said third vehicular wheel to which said third wheel cylinder is associated to produce a third wheel speed indicative signal; a fourth sensor means for monitoring a longitudinal acceleration exerted on a vehicle body for producing a longitudinal acceleration indicative signal; a first arithmetic means for providing a predetermined offset value to said longitudinal acceleration indicative signal and integrating the offset longitudinal acceleration indicative signal for deriving a wheel speed deceleration magnitude indicative data, and subtracting said wheel speed deceleration magnitude indicative data from an initial value which corresponds to one of said first, second and third wheel speed indicative signal values having the greatest value at the beginning of each skid control cycle for deriving a vehicle body speed representative data; and a second arithmetic means for controlling said pressure control valve means in a first mode for placing said pressure control valve in said first position, in a second mode for placing said pressure control valve means in said second position in a third mode for placing said pressure control valve means to said third position, said second arithmetic means deriving a control signal for selecting said first and second mode on the basis of said wheel speed indicative signal and said vehicle body speed representative data so as to maintain a wheel slippage within a predetermined range.

Claim 13

An anti-skid brake control system as set forth in claim 9, wherein said first arithmetic means operates in a normal arithmetic mode for deriving said vehicle body speed representative data to a value corresponding to said one of said first, second and third wheel speed indicative signal values having the greatest value and a skid control state arithmetic mode for deriving said vehicle body speed on the basis of said initial value and said integrated value of said offset longitudinal acceleration indicative value in said skid cycle.

Claim 14

An anti-skid brake control system as set forth in claim 10, wherein said first means derives a wheel acceleration and compared said wheel acceleration with a predetermined threshold value so as to select said said normal arithmetic mode when said wheel acceleration is maintained greater than or equal to said threshold value and to select said skid control state arithmetic mode otherwise.

Claim 15

An anti-skid brake control system as set forth in claim 11, wherein said first means further compares said vehicle body speed representative data and said wheel speed indicative signal value so as to permit said normal arithmetic mode operation when said wheel speed indicative signal value is greater than or equal to said vehicle body speed representative data.

Claim 16

An anti-skid brake control system as set forth in claim 9, wherein said second arithmetic means derives a wheel acceleration with respect to each of said first, second and third wheel speed indicative signals and a wheel slippage on the basis of said vehicle body speed representative data and each of said first, second and third wheel speed indicative signals, said second arithmetic means derives anti-skid control signal for each of the first, second and third pressure control valve for operating the latter to one of said first, second and third modes, said second means deriving said anti-skid brake control signal to order said third mode in response to the wheel acceleration smaller than or equal to a predetermined deceleration threshold, to order said second mode in response the wheel slippage greater than or equal to a predetermined wheel slippage threshold, to order said third mode when wheel acceleration is greater than or equal to a predetermined acceleration threshold, and to order said first mode when wheel slippage is smaller than said wheel slippage threshold and said wheel acceleration is smaller than said wheel acceleration threshold and greater than said wheel deceleration threshold.

Claim 17

An anti-skid brake control system as set forth in claim 9, wherein said second arithmetic means derives a wheel acceleration with respect to each of said first, second and third wheel speed indicative signals and a wheel slippage on the basis of said vehicle body speed representative data and each of said first, second and third wheel speed indicative signals, said second arithmetic means derives anti-skid control signal selecting one of for each of the first, second and third mode for operating said pressure control valve to corresponding one of said first, second and third positions according to the following sequence, said second means deriving said anti-skid brake control signal to order said third mode in response to decreasing of the wheel acceleration across to a predetermined deceleration threshold, to order said second mode in response increasing of the wheel slippage across a predecermined wheel slippage threshold, to order said third mode in response to increasing of said wheel acceleration across a predetermined acceleration threshold, and to order said first mode in response to decreasing of said wheel slippage across said vehicle body speed representative data.