Brake control system for pulsing vehicle brakes at variable pulse rates

Claim 2

A brake control system for applying a braking force to a vehicle wheel responsive to provision of a braking command, including actuator means connected in the braking system, operative upon energization to reduce the level of the applied braking force to prevent wheel skid, and operative upon deenergization to terminate reduction of the braking force and allow the braking system to commence restoration of the braking force, in which the improvement comprises: a timer arrangement connected to energize and deenergize the actuator means in a cyclical manner at a first rate; an input circuit connected to initiate operation of said timer arrangement upon receipt of both a first signal indicating the braking command has been provided and a second signal indicating deceleration of the braked vehicle wheel has exceeded a preset level; means for applying said first signal to the input circuit upon provision of the braking command; means, including a first sensor means, for applying said second signal to the input circuit when the deceleration of the braked wheel exceeds the preset level; a timer modification unit connected to change the cyclical operation of said timer arrangement from the first rate to a second rate upon receipt of a third signal indicating deceleration of the braked vehicle has exceeded a predetermined level; and means, including a second sensor means for applying said third signal to the timer modification unit when the deceleration of the braked vehicle exceeds the predetermined level.

Claim 3

A brake control system as claimed in claim 1 in which said timer arrangement comprises a multivibrator circuit, including at least one resistor-capacitor circuit connected to provide a predetermined time constant for regulating operation of the timer arrangement at said first rate, and switching means actuable in response to a control signal from said timer modification unit to change the effective value of said time constant to effect operation of said timer arrangement at said second rate.

Claim 4

A brake control system as claimed in claim 1 in which said actuator means includes an electrical winding, and an amplifier circuit is coupled between said timer arrangement and said winding to effect energization and deenergization of the winding at a rate determined by the operating rate of said timer arrangement.

Claim 5

A brake control system as claimed in claim 1 in which said first sensor means includes a normally closed mechanical switch, which switch is connected to open when the level of deceleration of the braked vehicle wheel exceeds the preset level.

Claim 6

A brake control system as claimed in claim 1, in which a delayed latching circuit is coupled between said first sensor means and said timer arrangement, to maintain operation of said timer arrangement for a predetermined time period after the first sensor means indicates the deceleration of the vehicle wheel is less than the preset level, and thereafter terminates operation of the timer arrangement, thus preventing continuous cycling of the brake control system when the brakes are still applied after the vehicle has come to a stop.

Claim 7

A brake control system as claimed in claim 1 in which said first sensor means includes a tachometer connected to be driven as a function of the angular displacement of said vehicle wheel to produce a series of velocity-indicating pulses, a differentiating stage connected to receive said pulses and provide an output signal connoting the deceleration level of the braked wheel, and a comparator stage, coupled between said differentiating stage and said input circuit, for passing said second signal to the input circuit when the comparator stage indicates the deceleration of the braked wheel exceeds the preset level.

Claim 8

A brake control system as claimed in claim 1 in which said first sensor means includes a substantially annular member having a series of radial markings, means for driving said annular member at an angular velocity related to the angular velocity of the braked vehicle wheel, means for directing a beam of radiation toward a reference location on said member to produce variations in the radiation level as said radial markings pass said reference location, a semiconductor unit positioned to sense the variations in radiation level to provide a series of output pulses related to the angular velocity of said vehicle wheel, a differentiating stage connected to receive said pulses and provide an output signal connoting the deceleration level of the braked wheel, and a comparator stage, coupled between said differentiating stage and said input circuit, for passing said second signal to the input circuit when the comparator stage indicates the deceleration of the braked wheel exceeds the preset level.

Claim 9

A brake control system as claimed in claim 7 in which said semiconductor unit is positioned to sense variations in the level of radiation reflected from said annular member as successive radial markings pass the reference location.

Claim 10

A brake control system as claimed in claim 1 in which the vehicle includes a prop shaft for transmitting power to the rear wheels, and in which said first sensor means includes a semiconductor unit positioned to sense variations in incident radiation level, means for providing a beam of radiation directed toward the semiconductor unit which means is driven at an angular velocity related to the angular velocity of the prop shaft and is positioned to vary the radiation beam to produce variations in the radiation level sensed by the semiconductor unit, thus providing a series of output pulses related to the angular velocity of said prop shaft, a differentiating stage connected to receive said pulses and provide an output signal connoting the deceleration level of the prop shaft, and a comparator stage, coupled between said differentiating stage and said input circuit, for passing said second signal to the input circuit when the comparator stage indicates the deceleration of the prop shaft exceeds the preset level.

Claim 11

A brake control system for applying a braking force to a vehicle wheel responsive to displacement of a brake pedal, including an actuator connected in the braking system, operative upon energization to reduce the level of the applied braking force to prevent wheel skid, and operative Upon deenergization to terminate reduction of the braking force and allow the braking system to commence restoration of the braking force, in which the improvement comprises: a multivibrator circuit connected to energize and deenergize the actuator in a cyclical manner, said multivibrator circuit including a timing circuit with an RC time-constant and a control switch connected for operation to change the value of the RC time-constant and correspondingly change the operation of the multivibrator circuit from a first rate to a second rate; an input circuit connected to initiate operation of said multivibrator circuit upon receipt of both a first signal indicating the brake pedal has been displaced and a second signal indicating deceleration of the braked vehicle wheel has exceeded a preset level; means, including a pedal switch, positioned to provide said first signal to the input circuit upon displacement of the brake pedal; means, including a first sensor, for applying said second signal to the input circuit when the deceleration of the braked wheel exceeds the preset level; a time constant modification circuit connected to change the cyclical operation of said multivibrator circuit from the first rate to the second rate upon receipt of a third signal indicating deceleration of the vehicle has exceeded a predetermined level; and means, including a second sensor, for applying said third signal to the time constant modification circuit when the deceleration of the vehicle exceeds the predetermined level.

Claim 12

A brake control system for applying a braking force to a vehicle wheel responsive to displacement of a brake pedal, including an actuator connected in the braking system, operative upon energization to reduce the level of the applied braking force to prevent wheel skid, and operative Upon deenergization to terminate reduction of the braking force and allow the braking system to commence restoration of the braking force, in which the improvement comprises: a multivibrator circuit connected to energize and deenergize the actuator in a cyclical manner, said multivibrator circuit including a timing circuit with an RC time-constant and a control switch connected for operation to change the value of the RC time-constant and correspondingly change the operation of the multivibrator circuit from a first rate to a second rate; an input circuit connected to initiate operation of said multivibrator circuit upon receipt of both a first signal indicating the brake pedal has been displaced and a second signal indicating deceleration of the braked vehicle wheel has exceeded a preset level; means, including a pedal switch, positioned to provide said first signal to the input circuit upon displacement of the brake pedal; means, including a first sensor, for applying said second signal to the input circuit when the deceleration of the braked wheel exceeds the preset level; a time constant modification circuit connected to change the cyclical operation of said multivibrator circuit from the first rate to the second rate upon receipt of a third signal indicating deceleration of the vehicle has exceeded a predetermined level; and means, including a second sensor, for applying said third signal to the time constant modification circuit when the deceleration of the vehicle exceeds the predetermined level.

Claim 13

A brake control system as claimed in claim 10 in which said actuator includes an electrical winding, and an amplifier circuit coupled between said multivibrator circuit and said winding to effect energization and deenergization of the winding at a rate determined by the operating rate of the multivibrator circuit.

Claim 14

A brake control system as claimed in claim 10 in which said first sensor includes a normally closed mechanical switch, which switch is connected to open when the level of deceleration of the braked wheel exceeds the preset level.

Claim 15

A brake control system as claimed in claim 10 in which said first sensor includes a tachometer coupled to said vehicle wheel to produce a series of velocity-indicating pulses, a differentiating stage connected to receive said pulses and provide an output signal signifying the deceleration level of the braked wheel, a comparator stage coupled between said differentiating stage and said input circuit, and an adjustable reference component coupled to said comparator stage for establishing a reference signal representing said preset level of wheel deceleration, so that the comparator stage passes said second signal to the input circuit when the comparator stage indicates the deceleration of the braked wheel exceeds the preset level.

Claim 16

A brake control system as claimed in claim 10 in which said first sensor includes a round member having a series of radial marks, means for driving the round member at an angular velocity related to the angular velocity of the braked wheel, means for directing a light beam toward a reference location on said member to produce variations in light level as the radial marks pass said reference location, a semiconductor unit positioned to sense the variations in light level to provide a series of output pulses related to the angular velocity of said vehicle wheel, a differentiating stage connected to receive said pulses and to provide an output signal connoting the wheel deceleration level, a comparator stage coupled between said differentiating stage and said input circuit, and an adjustable reference component coupled to said comparator stage for establishing a reference signal representing said preset level of wheel deceleration, so that the comparator stage passes said second signal to the input circuit when the comparator stage indicates the deceleration of the braked wheel exceeds the preset level.

Claim 17

A brake control system as claimed in claim 14 in which Said semiconductor unit is positioned to sense variations in the level of light reflected from said round member as successive radial marks pass the reference location.

Claim 18

A brake control system as claimed in claim 10, in which a delayed latching circuit is coupled between said first sensor and said multivibrator circuit, to maintain operation of the multivibrator circuit for a predetermined time period after the first sensor indicates the wheel deceleration is less than the preset level, and thereafter terminates operation of the multivibrator circuit to prevent continuous cycling of the brake control system when the brake pedal is still displaced after the vehicle has come to a stop.

Claim 19

A brake control system as claimed in claim 10, in which a delayed latching circuit is coupled between said second sensor and said control switch which changes the value of the RC time-constant in the multivibrator circuit, to maintain said control switch actuated for a predetermined time period after the second sensor indicates the vehicle deceleration is less than the predetermined level, and thereafter allows restoration of said control switch to again provide operation of said multivibrator circuit at said first rate.

Claim 20

A brake control system as claimed in claim 10 in which the vehicle includes a prop shaft for transmitting power to the rear wheels, and in which said first sensor includes a semiconductor unit positioned to sense variations in incident radiation level, means for providing a beam of radiation directed toward the semiconductor unit, means which is driven at an angular velocity related to the angular velocity of the prop shaft and is positioned to vary the radiation beam to produce variations in the radiation level sensed by the semiconductor unit, thus providing a series of output pulses related to the angular velocity of said prop shaft, a differentiating stage connected to receive said pulses and provide an output signal connoting the deceleration level of the prop shaft, and a comparator stage, coupled between said differentiating stage and said input circuit, for passing said second signal to the input circuit when the comparator stage indicates the deceleration of the prop shaft exceeds the preset level.

Claim 21

A brake control system for applying a braking force to a vehicle wheel responsive to displacement of a brake pedal coupled to a master cylinder, including a wheel cylinder coupled to a braking member for the vehicle wheel, and an actuator comprising a bore portion coupled between the master cylinder and the wheel cylinder, a piston displaceable in the actuator to increase and decrease the effective volume of the bore, an electrical winding disposed to displace said piston to vary the bore volume as said winding is energized, and a bias spring positioned to return said piston toward its original position after said winding is deenergized, in which the improvement comprises: a multivibrator circuit connected to energize and deenergize the actuator winding in a cyclical manner, said multivibrator circuit comprising first and second RC timing circuits with first values of time constants to provide multivibrator operation at a first rate, and first and second control switches connected for operation responsive to receipt of a control signal to change the values of the RC timing circuits to second values to effect multivibrator operation at a second rate; an input circuit connected to initiate operation of the multivibrator circuit at said first rate upon receipt of both a first signal indicating the brake pedal has been displaced and a second signal indicating deceleration of the braked wheel has exceeded a preset level; means, including an electrical switch positioned for actuation by displacement of the brake pedal, for applying said first signal to the input circuit; means, including a first sensor, for applying said second signal to the input circuit when the wheel deceleration exceeds the preset level; a time constant modificAtion circuit connected to apply said control signal to the first and second control switches in the multivibrator circuit and effect operation of the multivibrator circuit at the second rate upon receipt of a third signal indicating vehicle deceleration has exceeded a predetermined level; and means, including a second sensor, for applying said third signal to the time constant modification circuit when the vehicle deceleration exceeds the predetermined level.

Claim 22

A brake control system for applying a braking force to a vehicle wheel responsive to displacement of a brake pedal coupled to a master cylinder, including a wheel cylinder coupled to a braking member for the vehicle wheel, and an actuator comprising a bore portion coupled between the master cylinder and the wheel cylinder, a piston displaceable in the actuator to increase and decrease the effective volume of the bore, an electrical winding disposed to displace said piston to vary the bore volume as said winding is energized, and a bias spring positioned to return said piston toward its original position after said winding is deenergized, in which the improvement comprises: a multivibrator circuit connected to energize and deenergize the actuator winding in a cyclical manner, said multivibrator circuit comprising first and second RC timing circuits with first values of time constants to provide multivibrator operation at a first rate, and first and second control switches connected for operation responsive to receipt of a control signal to change the values of the RC timing circuits to second values to effect multivibrator operation at a second rate; an input circuit connected to initiate operation of the multivibrator circuit at said first rate upon receipt of both a first signal indicating the brake pedal has been displaced and a second signal indicating deceleration of the braked wheel has exceeded a preset level; means, including an electrical switch positioned for actuation by displacement of the brake pedal, for applying said first signal to the input circuit; means, including a first sensor, for applying said second signal to the input circuit when the wheel deceleration exceeds the preset level; a time constant modificAtion circuit connected to apply said control signal to the first and second control switches in the multivibrator circuit and effect operation of the multivibrator circuit at the second rate upon receipt of a third signal indicating vehicle deceleration has exceeded a predetermined level; and means, including a second sensor, for applying said third signal to the time constant modification circuit when the vehicle deceleration exceeds the predetermined level.

Claim 23

A brake control system as claimed in claim 19 in which the vehicle includes a prop shaft for transmitting power to the rear wheels, and in which said first sensor includes a light-sensitive unit positioned to sense variations in incident light level, means for providing light directed toward the light-sensitive unit which means is driven at an angular velocity related to the angular velocity of the prop shaft and is positioned to vary the light beam to produce variations in the light level sensed by the semiconductor unit, thus providing a series of output pulses related to the angular velocity of said prop shaft, a differentiating stage connected to receive said pulses and provide an output signal connoting the deceleration level of the prop shaft, and a comparator stage, coupled between said differentiating stage and said input circuit, for passing said second signal to the input circuit when the comparator stage indicates the deceleration of the prop shaft exceeds the preset level.