Electro-hydraulic braking systems

An electro-hydraulic braking system for motor vehicles which comprises a brake pedal, a braking device which is associated with at least one vehicle wheel and is capable of being brought into communication with an electronically controlled valve arrangement in order to apply hydraulic fluid under pressure to the braking device, a hydraulic pump, and a fluid pressure accumulator fed by the pump, for the provision of pressurized hydraulic fluid which can be passed to the braking device via the electronically controlled valve arrangement, in order to apply hydraulic fluid under pressure, in proportion to the driver's braking demand as sensed at the brake pedal, to the braking device in a ‘brake by wire’ mode, a first means which 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 to be met in use of the vehicle, and a second means which, upon recognition of a braking demand level or of a potential braking demand level which exceeds or will exceed that which can be achieved by said highest value of fluid pressure supply available via said first means, establishes a higher level of fluid pressure supply within the system for controlling the brakes in accordance with the driver's demanded braking level, characterized in that said second means is adapted to start the pump to charge the accumulator to a higher level, either when the demanded pressure level rises to a level which is higher than that which is currently available from the accumulator, or in advance of a high demand condition, in accordance with a detected or predicted level of brake fade, or lining fade change.

An electro-hydraulic braking system for motor vehicles, comprising:

• a brake pedal;
• a braking device which is associated with at least one vehicle wheel and is capable of being brought into communication with an electronically controlled valve arrangement in order to apply hydraulic fluid under pressure to the braking device;
• a hydraulic pump;
• a hydraulic pressure reservoir fed by the hydraulic pump for providing pressurized hydraulic fluid to the braking device via the electronically controlled valve arrangement in proportion to the driver's braking demand sensed at the brake pedal and at a fluid pressure supply level less than a maximum possible braking demand level which may be required to be met in use of the vehicle;
• a shut-off valve positioned between the hydraulic pump and the hydraulic-pressure reservoir, the shut-off valve being capable of isolating the hydraulic pressure reservoir from the braking device to increase the electro-hydraulic braking system stiffness;
• and
• an electronic control unit monitoring operation of the brake system and controlling operation of the shut-off valve to close the shut-off valve upon recognition of a higher braking demand or a potential higher braking demand that exceeds or will exceed that which can be achieved by the fluid pressure supply level from the hydraulic pressure reservoir, wherein the braking device is charged directly from the hydraulic pump to a higher fluid pressure supply level that corresponds to at least the driver's braking demand.

An electro-hydraulic braking system for motor vehicles, comprising:

• a brake associated with at least one vehicle wheel;
• an electronically controlled valve arrangement in fluid communication with the brake for applying hydraulic fluid under pressure to the brake;
• a hydraulic pump;
• a pressure reservoir in fluid communication with the hydraulic pump for providing pressurized hydraulic fluid to the brake through the electronically controlled valve arrangement in proportion to a driver's braking demand level;
• and
• an electronic control unit adapted to start the hydraulic pump to charge the pressure reservoir to a higher level in advance of a high demand condition in accordance with a detected or predicted level of brake fade or lining fade change.