Lucas Industries Limited

Lucas Industries Public Limited Company

Other

Trw Limited

Alan Leslie Harris

Mark Ian Phillips

Mark Leighton Howell

Peter Martin

Ivan Mortimer

Andrew W Kingston

Robert George Uzzell

Salvatore Oliveri

Barry John Bridgens

Simon David Stevens

Robert L Ferger

Alfred K White

Keith Lawrence Holding

Robert Gregory Fuller

Michael John Holt

Dennis Turner

Karl-Friedrich W&ouml;rsdorfer

Karl Friedrich Worsdorfer

An electro-hydraulic braking system of the type which operates normally in a brake-by-wire mode wherein hydraulic pressure is applied to braking devices at the vehicle wheels in proportion to the driver's braking demand as sensed electronically at a brake pedal, and which, if the brake-by-wire mode should fail, at least as far as the front brakes are concerned, operates in a push-through mode wherein hydraulic pressures are applied to the braking devices at the front wheels of the vehicle by way of a tandem master cylinder coupled mechanically to the brake pedal, wherein, in the situation where push-through operation has been selected at the front brakes but the rear brakes are continuing to be operated under EHB, a rear brake demand is calculated as a &ldquo;multiple average&rdquo; from the expression: &lsqb;P &plus;(P &plus;P )/2&rsqb;/2 where P and P are signals from the master cylinder and a front brake sensor in the same push-through circuit and P is a signal from the front brake sensor in the other circuit.

Rear-axle demand for use with front push-through in electrohydraulic (EHB) braking systems

A method of detection and identification of pressure sensor faults in an electro-hydraulic braking system of the type comprising a brake pedal, respective braking devices connected to the vehicle wheels and which communicate with electronically controlled proportional control valves in order to apply hydraulic fluid under pressure to the braking devices, respective pressure sensors for measuring the hydraulic pressures at the individual braking devices, a hydraulic pump driven by an electric motor, a high pressure hydraulic pressure accumulator fed by the pump for the provision of hydraulic fluid under pressure which can be passed to the braking devices via the proportional control valves in order to apply hydraulic fluid under pressure to the braking devices in proportion to the driver's braking demand as sensed at the brake pedal, and a supply pressure sensor for monitoring the hydraulic pressure supplied to the electronically controlled proportional control valves. In accordance with the method, three or more of the pressure sensors are arranged to be subjected to the same pressure and their readings measured and compared whereby to identify a sensor whose reading does not correspond to that of the others.

Detection and identification of pressure-sensor faults in electro-hydraulic (EHB) braking systems

A vehicle braking system comprising an electro-hydraulic braking system of the type which operates normally in a brake-by-wire mode wherein hydraulic pressure is applied to braking devices at the vehicle wheels ( ) in proportion to the driver's braking demand as sensed electronically at a brake pedal ( ), and which, if the brake-by-wire mode should fail, operates in a push-through mode wherein hydraulic pressure is applied to the braking devices at the vehicle wheels ( ) by way of a master cylinder ( ) coupled mechanically to the braked pedal ( ), and an electric parking braking system for enabling the braking devices to be actuated for parking braking purposes. For supplementing the push-through braking provided by the electro-hydraulic braking system in the event that the brake-by-wire mode has failed, it is arranged that the operation of the brake pedal ( ) by the driver also causes operation of the electric parking braking system.

Back-up braking in vehicle braking systems

A vehicle braking system of the type in which a stored volume of fluid is used to apply the wheel brakes of the vehicle under the control of an electronic unit, the stored volume being held in an accumulator arranged to be replenished by pumping additional working fluid using a pump driven by an electric motor. The speed of the pump electric motor is arranged to be controlled in dependence upon whether or not any vehicle dynamic intervention, such as ABS, TC and VSC, is active. If it is deduced that one or more vehicle dynamic functions is active, then the pump is arranged to be run at high/full, and relatively noisy, speed, but if it is concluded that only base braking is being applied with no vehicle dynamic function being active, then the pump is arranged to be operated at a relative slower and hence quieter speed.

Pump motor control in electro-hydraulic braking systems

An electro-hydraulic braking system of the type which operates normally in a brake-by-wire (EHB) mode wherein hydraulic pressure is applied to braking devices at the vehicle wheels in proportion to the driver's braking demand as sensed electronically at a brake pedal, but which, if the brake-by-wire mode should fail, operates in a push-through mode wherein hydraulic pressure is applied to the braking devices at the vehicle wheels by way of a master cylinder coupled mechanically to the brake pedal. In order to minimize jolting within the system when changeover from push-through to brake-by-wire braking takes place, the existence of a push-through condition is recognized during an initialization stage of the EHB mode and the initial EHB demand is set at the prevailing push-through braking or deceleration level and then adapted smoothly to the desired EHB demand.

Electro-hydraulic braking system

An electro-hydraulic braking system of the type which operates normally in a brake-by-wire mode wherein hydraulic pressure is applied to braking devices at the vehicle wheels in proportion to the driver's braking demand as sensed electronically at a brake pedal ( ), and which, if the brake-by-wire mode should fail, operates in a push-through mode wherein hydraulic pressure is applied to the braking devices at the vehicle wheels by way of a master cylinder ( ) coupled mechanically to the brake pedal ( ), the system including also an electric parking braking device for enabling the braking devices to be actuated for parking braking purposes but which is also arranged to be activated to supplement push-through braking in the event of failure of the brake-by-wire mode. Electro-hydraulic braking at the rear axle of the vehicle is allowed only when a control unit ( ) of the electro-hydraulic braking system has confirmation that the electric parking device is in a satisfactory operational state.

Back-up braking in electro-hydraulic (EHB) braking system

An electro-hydraulic braking system of the type capable of operating in a braking-by-wire mode wherein hydraulic pressure is applied to braking devices at the vehicle wheels in proportion to the driver's braking demand as sensed electronically at a brake pedal, in a push-through mode wherein hydraulic pressure is applied to the braking devices at the vehicle wheels by way of a master cylinder coupled mechanically to the brake pedal and in an ABS mode in which the braking pressures at the individual wheels are controlled in dependence, inter alia, on the detected rotational behavior of the vehicle wheels, and which includes a hydraulic travel simulator which is connected hydraulically to the master cylinder by way of an electrically controlled isolation valve for providing improved feel for the driver through the brake pedal in the push-through operating mode. In order to ensure that the brake pedal cannot be pushed beyond a position corresponding to a wheel-locking pressure, and thereby make it easier for the driver to modulate the brake pressure and avoid excessive deceleration if the road adhesion improves, the travel simulator isolation valve is arranged to be closed when the ABS mode is active.

Pedal travel limitation in electro-hydraulic (EHB) braking systems

An electro-hydraulic braking system for motor vehicles. The system includes a brake pedal and a braking device associated with at least one vehicle wheel which is brought into communication with an electronically controlled valve arrangement in order to apply hydraulic fluid under pressure to the braking device. A fluid pressure accumulator fed by the pump provides a pressurized hydraulic fluid which can be passed to the braking device by way of an electronically controlled valve arrangement in order to apply hydraulic fluid in proportion to the driver braking demand as sensed at the brake pedal in the &ldquo;brake by wire&rdquo; mode. A first device within the system provides a level of fluid pressure supply within the electro-hydraulic system whose highest value is less than that sufficient for the maximum possible braking demand level which may be required. A second device within the system recognizes a braking demand level which exceeds that which can be achieved by the highest value of fluid pressure available by the first device and establishes a higher level of fluid pressure supply within the system for controlling the brakes in accordance with the driver's demanded braking level.

Electro-hydraulic braking systems

An electronic braking system for a vehicle wherein control of the vehicle brakes is achieved by the use of electric control signals generated at a brake pedal in response to a driver's braking demand and an electronic controller which is adapted to control the supply of fluid under pressure from a power source to the brakes in accordance with said electronic signals corresponding to the driver's demand, the system being adapted to raise the brake pressure to a first predetermined level(jump-in) at a prescribed level of initial brake pedal travel and to release the brake pressure (reverse jump-in) as a second predetermined level, which is lower than at jump-in. The jump-in brake pressure level can be arranged to be variable with vehicle speed. In some cases, the brakes are arranged to be prefilled to a low pressure at a low pressure at an early stage in the pedal travel and then maintained at that low level until jump-in is triggered, whereupon the braking pressure is raised to the jump-in level. In other cases where jump-in is not necessarily used, the prefill pressure is maintained at that level until actual brake demand exceeds the prefill pressure whereupon the brake pressure is then controlled in accordance with actual brake demand.

Electronic braking system for vehicles

A reservoir assembly for a vehicle hydraulic braking system includes two chambers (,) for the storage of hydraulic fluid. The reservoir assembly is provided with a structure for increasing the effective volume of one of the chambers (,), for example a bellows (,) or a bucket (,), and which may be operable in conjunction with the fitting of a filler cap (,) to seal a filler opening (,) for that chamber. This enables a volume of fluid to be accommodated in a chamber of increased volume, thereby substantially eliminating the possibility of volume in excess of a given volume from overflowing from the chamber (,). When the reservoir assembly is installed in a vehicle braking system of a brake-by-wire electro-hydraulic type (EMB) having a first power circuit (,), and a second back-up hydrostatic circuit (,), the one chamber (,) supplies fluid to the hydrostatic circuit, and the other chamber (,) supplies fluid to the power circuit.

Reservoir assemblies for hydraulic vehicle braking systems

An hydraulic braking system of the brake-by-wire type has an hydraulic pressure source comprising an hydraulic accumulator adapted to be charged by a pump. An accumulator isolating valve is so positioned and biased to correspond to the direction of flow from the accumulator to a solenoid-operated proportional valve. The valve is biased into a closed position in opposition to the flow from the pump to the accumulator.

Hydraulic braking systems of the brake-by-wire type for vehicles

A vehicle hydraulic braking system of the brake-by-wire type is disclosed in which proportional solenoid-operated valves (12, 13) are adapted to control the pressure in wheel brake actuators of the brakes (8, 9) on a single axle of a vehicle, and a balance valve (20) is provided to enable individual hydraulic brake circuits to be hydraulically connected so that the pressure applied to each brake is guaranteed to be substantially the same, a first one (13) of the proportional valves (12, 13) is adapted to be isolated so that the hydraulic circuit is fed by a second, single, proportional valve (12). Applying both brakes under the control of a single proportional valve ensures that any fluid leakages are balanced since substantially equal brake-applying pressures are generated. An alternative vehicle hydraulic braking system of the brake-by-wire type is also disclosed in which a control module (3) is provided which is adapted to select between at least a first control mode (104) in which more than one of the proportional valves (12, 13) is adapted to be controlled in parallel and a second control mode (103) in which only one of the proportional valves (12, 13) is operated to control the pressure in the wheel brake actuators.

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Coventry, United Kingdom

Alan Leslie Harris