Road vehicle braking system incorporating wheel slide protection

Claim 2

A road vehicle braking system incorporating wheel slide protection, comprising in combination first and second sensors associated respectively with first and second wheels of the vehicle and producing first and second a.c. signals at frequencies dependent on the rotational speeds of the first and second vehicle wheels respectively, first and second frequency to voltage Converters for producing from said first and second a.c. signals first and second d.c. signals dependent on said rotational speeds of the first and second vehicle wheels respectively, first and second differentiating circuits to which the first and second d.c. signals are fed respectively, the differentiating circuits producing output signals dependent on the rotational decelerations of the first and second wheels, means operable by way of the output signals from the first and second differentiating circuits for releasing the brakes applied to the first and second wheels respectively, when the output signals from the first and second differentiating circuits exceed predetermined values, and monitoring means operable to compare the outputs from the first and second sensors and in the event of a difference in the outputs of the first and second sensors to prevent releasing of the brakes of the first and second wheels during a subsequent braking operation, the output signals of the sensors being compared with each other by sampling the output signals of the first and second frequency to voltage converters, the output signals from the converters being applied to a bridge network which produces an output when the output signals from the converters are not equal.

Claim 3

A system as claimed in claim 1 in which more than two sensors are provided, or the sensors providing inputs to the bridge network so that if any two inputs to the bridge network differ in potential by a predetermined amount, the bridge network produces an output signal.

Claim 4

A road vehicle braking system incorporating wheel slide protection, comprising in combination first and second sensors associated respectively, with first and second wheels of the vehicle and producing first and second a.c. signals at frequencies dependent on the rotational speeds of the first and second vehicle wheels respectively, first and second frequency to voltage converters for producing from said first and second a.c. signals first and second d.c. signals dependent on said rotational speeds of the first and second vehicle wheels respectively, first and second differentiating circuits to which the first and second d.c. signals are fed respectively, the differentiating circuits producing output signals dependent on the rotational decelerations of the first and second wheels, means operable by way of the output signals from the first and second differentiating circuits for releasing the brakes applied to the first and second wheels respectively when the output signals from the first and second differentiating circuits exceed predetermined values, first and second diodes, the anode of the first diode and the cathode of the second diode being connected to the output from the first differentiating circuit, third and fourth diodes, the anode of the third diode and the cathode of the fourth diode being connected to the output of the second differentiating circuit, a line connected to the cathodes of the first and third diodes, a line connected to the anodes of the second and fourth diodes, a transistor having its base connected to one of said lines and its emitter connected to the other of said lines, and a control network coupled to the collector of said transistor and operable by current flow in the collector of said transistor, said control network serving when said transistor conducts to prevent releasing of the brakes during a subsequent braking operation.

Claim 5

A road vehicle braking system incorporating wheel slide protection, comprising in combination first and second sensors associated respectively, with first and second wheels of the vehicle and producing first and second a.c. signals at frequencies dependent on the rotational speeds of the first and second vehicle wheels respectively, first and second frequency to voltage converters for producing from said first and second a.c. signals first and second d.c. signals dependent on said rotational speeds of the first and second vehicle wheels respectively, first and second differentiating circuits to which the first and second d.c. signals are fed respectively, the differentiating circuits producing output signals dependent on the rotational decelerations of the first and second wheels, means operable by way of the output signals from the first and second differentiating circuits for releasing the brakes applied to the first and second wheels respectively when the output signals from the first and second differentiating circuits exceed predetermined values, first and second diodes, the anode of the first diode and the cathode of the second diode being connected to the output from the first differentiating circuit, third and fourth diodes, the anode of the third diode and the cathode of the fourth diode being connected to the output of the second differentiating circuit, a line connected to the cathodes of the first and third diodes, a line connected to the anodes of the second and fourth diodes, a transistor having its base connected to one of said lines and its emitter connected to the other of said lines, and a control network coupled to the collector of said transistor and operable by current flow in the collector of said transistor, said control network serving when said transistor conducts to prevent releasing of the brakes during a subsequent braking operation.