Fluid-pressure operated boosters for vehicle braking systems

Claim 2

A fluid-pressure operated booster for a vehicle braking system in which operation of the booster (2) is adapted to be controlled by solenoid-operated valve means (A, B), characterised in that energisation of the booster (2) is controlled solely by operation of the solenoid-operated valve means (A, B) in response to signals from an electronic controller (15).

Claim 3

A vehicle braking system incorporating a booster according to claim 1, characterised in that the electronic controller (15) is adapted to receive signals from wheel speed sensors (11, 12, 13, 14) sensing the behaviour of wheels (5, 6, 9, 10) and signals generated by operation of electrical means (47, 70, 95, 96, 110, 111) responsive to operation of a pedal (44).

Claim 4

A braking system according to claim 2, characterised in that the electrical means comprises a pedal-operated electrical switch (47, 70).

Claim 5

A braking system according to claim 2, characterised in that the electrical means comprises a load cell (95, 110) associated with a member (42, 71) responsive to operation of the pedal, and a load cell (96, 111) associated with an output rod (50, 77) of the booster.

Claim 6

A braking system according to any of claim 2-4, characterised in that normal operation of the booster is initiated by pedal operation of the electrical means with the controller (15) operating the solenoid-operated valve means (A, B) to achieve conventional operation of the booster.

Claim 7

A braking system according to any of claims 2-4, characterised in that when the pedal is in a normal inoperative position and a wheel speed sensor (11, 12, 13, 14) emits a signal indicative of a 'wheel-spin' condition the controller (15) is adapted to operate the solenoid-operated valve means (A, B) independently of the pedal to apply a brake on the spinning wheel.

Claim 8

A vehicle hydraulic braking system including a fluid-pressure operated booster (2) according to claim 1, in which the pressure of fluid supplied to a wheel brake (3, 4, 7, 8) from a master cylinder (1) operated by the booster (2) is adapted to be modulated by a modulator (3′, 4′, 7′, 8′) in response to a signal from the electronic controller (15) which, in turn, is initiated by a signal from a wheel speed sensor (11, 12, 13, 14) operated by that brake, characterised in that a given pressure generated by the master cylinder (1) is adapted to be modified by the modulator in response to signals from the controller to achieve an appropriate brake-applying pressure.

Claim 9

A braking system according to claim 7, characterised in that the controller (15) is adapted to look at pulses indicative of the approach of a critical rate of output from the booster (2) and above which normal smooth operation of the brake is difficult to achieve, and the controller (15) is then adapted to actuate the modulator to control smoothly the subsequent rate of pressure increase applied to the brake.

Claim 10

A braking system according to claim 8, characterised in that the master cylinder (1) acts as an hydraulic accumulator having a range of progressively increasing stepped output pressures, and the modulator is adapted to determine the actual pressure which is applied to the brake by modifying the output from the accumulator, at least up to the maximum of a given step.

Claim 11

A braking system according to any of claim 2-9, characterised in that the booster (2) is adapted to be controlled by the electronic controller (15) in response to a wheel anti-lock signal from a wheel speed sensor (11, 12, 13, 14), whereby to reduce the level of pressure applied to the respective brake.

Claim 12

A vehicle braking system including a fluid-pressure operated booster (2) according to claim 1, characterised in that the booster (2) is adapted to be controlled by the electronic controller (15) in response to a radar signal from a radar transmitter on the vehicle.

Claim 13

A vehicle braking system according to any of claims 2-11, characterised in that the booster (2) is adapted to modify its boost ratio to provide substantially the same vehicle deceleration for a given predetermined pedal effort irrespective of the laden condition of the vehicle.

Claim 14

A vehicle braking system according to any of claims 2-12, characterised in that the booster (2) is adapted to be operated by the electronic controller (15) to hold the vehicle on a hill or incline with the clutch pedal depressed.

Claim 15

A vehicle braking system according to any of claim 2-13, characterised in that the solenoid-operated valve means (A, B) comprises first and second independently operable solenoid-operated valves (A, B), and the valves are adapted to be operated in any desired sequence in accordance with the nature of signals from the electronic controller (15).