Apparatus for indicating changes in angular velocity, and vehicle braking systems employing such apparatus

Claim 2

Apparatus for indicating changes in the angular velocity of a rotating body which may be subjected to acceleration/deceleration, said apparatus comprising: velocity sensing means including a toothed disc at least partly made of ferromagnetic material and secured to said body for rotation therewith and a variable reluctance transducer cooperating with said disc and adapted to produce an electric signal having a frequency proportional to the angular velocity of said body, a converter for converting said signal to a direct current signal, the level of which varies with variations in said frequency, a differentiator for differentiating said direct current signal, said differentiator including a circuit arrangement adapted in operation to differentiate relatively low frequency signals and to integrate relatively high frequency signals, and a comparator for comparing the differentiated signal with a reference signal derived from an external source, said comparator being arranged to produce an output signal whenever the two signals compared differ by at least a predetermined magnitude, said output signal being usable to actuate means adapted to reduce the acceleration/deceleration of said body.

Claim 3

Apparatus for indicating changes in the angular velocity of a rotating body which may be subjected to acceleration/deceleration, said apparatus comprising: velocity sensing means adapted to produce an electric signal having a frequency proportional to the angular velocity of said body, a converter for converting said signal to a direct current signal the level of which varies with variations in said frequency, a differentiator for differentiating said direct current signal, said differentiator including a circuit arrangement adapted in operation to differentiate relatively low frequency signals and to integrate relatively high frequency signals, and a comparator for comparing the differentiated signal with a reference signal derived from an external source, said comparator being arranged to produce an output signal whenever the two signals compared differ by at least a predetermined magnitude, said output signal being usable to actuate means adapted to reduce the acceleration/deceleration of said body, and wherein the said circuit arrangement includes a high gain operational amplifier, an input resistor and an input capacitor connected in series, and a feedback resistor and a feedback capacitor connected in parallel with each other and across the amplifier, the time constants of the input resistor and feedback capacitor on the one hand, and of the feedback resistor and input capacitor on the other hand being approximately equal and intermediate the said relatively low and high frequencies.

Claim 4

Apparatus for indicating changes in the angular velocity of a rotating body which may be subjected to acceleration/deceleration, said apparatus comprising: velocity sensing means adapted to produce an electric signal having a frequency proportional to the angular velocity of said body, a converter for converting said signal to a direct current signal the level of which varies with variations in said frequency, a differentiator for differentiating said direct current signal, said differentiator including a circuit arrangement adapted in operation to differentiate relatively low frequency signals and to integrate relatively high frequency signals, and a comparator for comparing the differentiated signal with a reference signal derived from an external source, said comparator being arranged to produce an output signal whenever the two signals compared differ by at least a predetermined magnitude, said output signal being usable to actuate means adapted to reduce the acceleration/deceleration of said body, and wherein the said circuit arrangement includes a high gain operational amplifier, an input resistor and an input capacitor connected in series, and a feedback resistor and a feedback capacitor connected in parallel with each other and across the amplifier, the time constants of the input resistor and feedback capacitor on the one hand, and of the feedback resistor and input capacitor on the other hand being approximately equal and intermediate the said relatively low and high frequencies.

Claim 5

Apparatus for indicating changes in the angular velocity of a rotating body which may be subjected to acceleration/deceleration, said apparatus comprising: velocity sensing means adapted to produce an electric signal having a frequency proportional to the angular velocity of said body, a converter for converting said signal to a direct current signal the level of which varies with variations in said frequency, a differentiator for differentiating said direct current signal, said differentiator including a circuit arrangement adapted in operation to differentiate relatively low frequency siGnals and to integrate relatively high frequency signals, a comparator for comparing the differentiated signal with a reference signal derived from an external source, said comparator being arranged to produce an output signal whenever the two signals compared differ by at least a predetermined magnitude, said output signal being usable to actuate means adapted to reduce the acceleration/deceleration of said body, and a Miller integrator circuit which is connected to receive the output of said circuit arrangement and the output of which is passed to said comparator.

Claim 6

Apparatus for indicating changes in the angular velocity of a rotating body which may be subjected to acceleration/deceleration, said apparatus comprising: velocity sensing means adapted to produce an electric signal having a frequency proportional to the angular velocity of said body, a converter for converting said signal to a direct current signal the level of which varies with variations in said frequency, a differentiator for differentiating said direct current signal, said differentiator including a circuit arrangement adapted in operation to differentiate relatively low frequency siGnals and to integrate relatively high frequency signals, a comparator for comparing the differentiated signal with a reference signal derived from an external source, said comparator being arranged to produce an output signal whenever the two signals compared differ by at least a predetermined magnitude, said output signal being usable to actuate means adapted to reduce the acceleration/deceleration of said body, and a Miller integrator circuit which is connected to receive the output of said circuit arrangement and the output of which is passed to said comparator.

Claim 7

A vehicle having a vehicle body, four road wheels and a braking system including apparatus associated with at least some of the braked road wheels for indicating changes in the angular velocity of a wheel which may be subjected to deceleration, said apparatus comprising: velocity sensing means adapted to produce an electric signal having a frequency proportional to the angular velocity of said wheel, a first converter for converting said signal to a direct current signal the level of which varies with variations in said frequency, a differentiator for differentiating said direct current signal, a decelerometer secured to the vehicle body, a filter for filtering the output of the decelerometer to remove therefrom components deriving from the mechanical vibrations of the vehicle body, a second converter to provide a voltage analogue signal of the deceleration of the vehicle body, and a comparator for comparing the differentiated signal with the voltage analogue signal, said comparator being arranged to produce an output signal whenever the two signals compared differ by at least a predetermined magnitude, said predetermined magnitude being indicative of the onset of wheel-locking, said output signal being used in operation to relieve the braking force applied to said wheels.

Claim 8

A vehicle having a vehicle body, four road wheels and a braking system including apparatus associated with at least some of the braked road wheels for indicating changes in the angular velocity of a wheel which may be subjected to deceleration, said apparatus comprising: velocity sensing means adapted to produce an electric signal having a frequency proportional to the angular velocity of said wheel, a first converter for converting said signal to a direct current signal the level of which varies with variations in said frequency, a differentiator for differentiating said direct current signal, a decelerometer secured to the vehicle body, a filter for filtering the output of the decelerometer to remove therefrom components deriving from the mechanical vibrations of the vehicle body, a second converter to provide a voltage analogue signal of the deceleration of the vehicle body, and a comparator for comparing the differentiated signal with the voltage analogue signal, said comparator being arranged to produce an output signal whenever the two signals compared differ by at least a predetermined magnitude, said predetermined magnitude being indicative of the onset of wheel-locking, said output signal being used in operation to relieve the braking force applied to said wheels.

Claim 9

A hydraulic braking system for a motor car having four braked wheels, solenoid valves being located in the said hydraulic braking system, there being at least one solenoid valve for each braked wheel, including apparatus for indicating changes in the angular velocity of a braked road wheel which may be subjected to deceleration, said apparatus comprising: velocity sensing means adapted to produce an electric signal having a frequency proportional to the angular velocity of said wheel, a converter for converting said signal to a direct current signal the level of which varies with variations in said frequency, a differentiator for differentiating said direct current signal, a comparator for comparing the differentiated signal with a reference signal derived from an external source, said comparator being arranged to produce an output signal whenever the two signals compared differ by at least a predetermined magnitude, said predetermined magnitude being indicative of the onset of wheel-locking, said output signal being used in operation to energize the said solenoid valves to relieve the braking force applied to said wheels, and wherein said hydraulic brake system includes two independent power-operated circuits and a brake pedal actuated master cylinder circuit.

Claim 10

A hydraulic braking system for a motor car having four braked wheels, solenoid valves being located in the said hydraulic braking system, there being at least one solenoid valve for each braked wheel, including apparatus for indicating changes in the angular velocity of a braked road wheel which may be subjected to deceleration, said apparatus comprising: velocity sensing means adapted to produce an electric signal having a frequency proportional to the angular velocity of said wheel, a converter for converting said signal to a direct current signal the level of which varies with variations in said frequency, a differentiator for differentiating said direct current signal, a comparator for comparing the differentiated signal with a reference signal derived from an external source, said comparator being arranged to produce an output signal whenever the two signals compared differ by at least a predetermined magnitude, said predetermined magnitude being indicative of the onset of wheel-locking, said output signal being used in operation to energize the said solenoid valves to relieve the braking force applied to said wheels, and wherein said hydraulic brake system includes two independent power-operated circuits and a brake pedal actuated master cylinder circuit.

Claim 11

A hydraulic braking system for a motor car having four braked wheels, solenoid valves being located in the said hydraulic braking system, there being at least one solenoid valve for each braked wheel, including apparatus for indicating changes in the angular velocity of a braked road wheel which may be subjected to deceleration, said apparatus comprising: velocity sensing means adapted to produce an electric signal having a frequency proportional to the angular velocity of said wheel, a converter for converting said signal to a direct current signal the level of which varies with variations in said frequency, a differentiator for differentiating said direct current signal, a comparator for comparing the differentiated signal with a reference to signal derived from an exterNal source, said comparator being arranged to produce an output signal whenever the two signals compared differ by at least a predetermined magnitude, said predetermined magnitude being indicative of the onset of wheel-locking, said output signal being used in operation to energize the said solenoid valves to relieve the braking force applied to said wheels, and a logic circuit, the said circuit being arranged to deenergize the system in case of failure and optionally to provide a warning indication also.

Claim 12

A hydraulic braking system for a motor car having four braked wheels, solenoid valves being located in the said hydraulic braking system, there being at least one solenoid valve for each braked wheel, including apparatus for indicating changes in the angular velocity of a braked road wheel which may be subjected to deceleration, said apparatus comprising: velocity sensing means adapted to produce an electric signal having a frequency proportional to the angular velocity of said wheel, a converter for converting said signal to a direct current signal the level of which varies with variations in said frequency, a differentiator for differentiating said direct current signal, a comparator for comparing the differentiated signal with a reference to signal derived from an exterNal source, said comparator being arranged to produce an output signal whenever the two signals compared differ by at least a predetermined magnitude, said predetermined magnitude being indicative of the onset of wheel-locking, said output signal being used in operation to energize the said solenoid valves to relieve the braking force applied to said wheels, and a logic circuit, the said circuit being arranged to deenergize the system in case of failure and optionally to provide a warning indication also.

Claim 13

Apparatus as claimed in claim 1 wherein a filter and buffer stage is interposed between the converter and the differentiator.

Claim 14

Apparatus as claimed in claim 1 wherein the said circuit arrangement includes a high gain operational amplifier, an input resistor and an input capacitor connected in series, and a feedback resistor and a feedback capacitor connected in parallel with each other and across the amplifier.

Claim 15

Apparatus as claimed in claim 1 wherein said converter includes a diode pump circuit.

Claim 16

A vehicle braking system including apparatus for indicating changes in angular velocity as claimed in claim 1 wherein said apparatus is associated with at least some of the braked road wheels of the vehicle, said output signal being used in operation to relieve the braking force applied to said wheels, said predetermined magnitude being indicative of the onset of wheel-locking

Claim 17

A vehicle braking system as claimed in claim 10 wherein said vehicle is a motor car having four braked wheels, the arrangement for using said output signal being such that the brakes of both wheels at one end of the car are released when either wheel is about to lock at that end.

Claim 18

A vehicle braking system as claimed in claim 10 wherein said vehicle is a motor car having four braked wheels, the arrangement for using said output signal being such that the brake means of each wheel is released independently of the brake means of the other wheels when said wheel is about to lock.

Claim 19

A vehicle braking system as claimed in claim 10 wherein the motor car has a hydraulic brake system, solenoid valves being located in the said hydraulic brake system, there being at least one solenoid valve for each braked wheel, said output signal being used in operation to energize the said solenoid valves.

Claim 20

A vehicle braking system as claimed in claim 5 wherein each braked wheel is provided with at least one opposed pair of brake caliper pistons which are independently operable.

Claim 21

A vehicle braking system as claimed in claim 5 wherein the solenoid valve associated with the master cylinder is electrically controlled to operate once only for each brake application and to stay energized while the brake pedal is depressed.

Claim 22

A vehicle braking system as claimed in claim 10 wherein said reference signal is derived from a vehicle power supply independent of said sensing means.

Claim 23

A vehicle braking system as claimed in claim 16 wherein said power supply is a battery, means being provided for stabilizing its output.

Claim 24

A vehicle braking system as claimed in claim 10 wherein a decelerometer is secured to the vehicle body, and said reference signal is derived from the output signal of said decelerometer.

Claim 25

A vehicle braking system as claimed in claim 18 wherein the output signal of said decelerometer is passed through a filter to remove therefrom components deriving from the mechanical vibrations of the vehicle body and converted to provide a voltage analogue signal of the deceleration of the vehicle body, said voltage analogue signal being then passed to said comparator.