An improved electro-hydraulic brake system having features for improving the pedal feel of the system, while further having design features which contribute to the economy of manufacture of certain components of the system. The system provides for an electrically powered normal source of pressurized hydraulic brake fluid, and a manually powered backup source of pressurized hydraulic brake fluid to the vehicle brakes in the event of failure of the normal source. During normal braking, fluid from the backup source is redirected from the vehicle brakes to a pedal simulator. The pedal simulator preferably includes arrangements of spring loaded pistons, expansion volumes, and damping orifices, together with valves selectively controlling the flow of fluid to and from the pedal simulator which provides for an improved pedal feel during vehicle braking. The brake system of the invention further includes a relatively low cost fluid separator unit which is provided which prevents intermixing of pressurized fluid between the backup source and the normal source. The fluid separator unit acts to permit the normal source to act upon the hydraulic brake fluid of the backup source to operate the vehicle brakes. The fluid separator unit is preferably embodied as a piston having two working faces, each of the same diameter.

Electronic brake management system with manual fail safe

The invention relates to a clutch system, comprising a clutch device (302), in particular for the arrangement in a drive train between a drive unit and a transmission, and also comprising an actuating device for actuating the clutch device hydraulically by means of at least one hydraulic slave cylinder of the clutch device, the actuating device being a hydraulic medium - Provisioning device (210a, 210b) for providing hydraulic medium at an adjustable pressure level which determines the actuation state of the clutch device via the slave cylinder It is proposed that the hydraulic medium supply device have a hydraulic medium pump arrangement (210a, 210b) which can be influenced with regard to a discharge pressure and / or a delivery quantity or / and a delivery direction, the hydraulic medium pump arrangement being arranged and set up for this by influencing the hydraulic medium pump arrangement, the pressure level and thus the actuation state is adjustable

Clutch system with a pump actuated clutch

An electro-hydraulic braking system for motor vehicles which comprises a brake pedal (101), a braking device (103) which is associated with at least one vehicle wheel and is capable of being brought into communication with an electronically controlled valve arrangement (109) in order to apply hydraulic fluid under pressure to the braking device, a hydraulic pump (110), and a fluid pressure accumulator (111) fed by the pump (110), for the provision of pressurised hydraulic fluid which can be passed to the braking device (103) via the electronically controlled valve arrangement (109), in order to apply hydraulic fluid under pressure, in proportion to the driver's braking demand as sensed at the brake pedal (101), to the braking device (103) in a 'brake by wire' mode. A first means 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 to be met in use of the vehicle. A second means within the system is arranged to recognize a braking demand level or 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, and to establish 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

The wheel brakes of each vehicle axle or side or diagonal are supplied with current by a separate voltage source. To reduce the load on the vehicle's electrical system, the wheel brakes of a front axle are supplied with current first, and then the wheel brakes of a rear axle are supplied with current.

Electric motor-driven wheel brake for vehicles

In a road vehicle electrohydraulic brake system, each wheel brake is assigned a brake-pressure regulating element which can be controlled by an electric motor. At least one electronic retardation desired-value signal transmitter is actuated by the driver. An electronic control unit produces the required actuating signals for the brake-pressure regulating elements from a comparison of the desired-value input signals with actual-value signals characteristic of the vehicle retardation. The brake-pressure regulating elements each comprises a piston pump. The filling and delivery strokes of these elements are performed in a fixed phase relationship with a pump driving element. The output of the pump per pump cycle is regulated opposite the pressure and, in all cases, is small relative to the output, Qmax, required for coupling the maximum value of the brake pressure PBmax into the connected wheel brake. With the vehicle stationary and the desired-value transmitter actuated, an electrically drivable valve arrangement shuts off the brakes from the brake-pressure regulating elements and, given a reduction in the desired-value input, allows brake fluid to flow out of the brakes into individually assigned reservoir chambers.

Road vehicle electrohydraulic brake system

Pressure-generating device for braking circuits of motor vehicles of the type having electric motors for controlling a device for generating braking pressure. Electric motors (15), associated with each wheel (1, 1', 2, 2') or pair of wheels (1,1'-2,2') of the same axle, drive positive displacement pumps (16) generating the braking pressure for cylinders (7) of brakes (3 to 6).

Pressure-generating device for braking circuits of motor vehicles

Circuit for controlling, regulating and monitoring a fluid flow, comprising: - a distributor (12) associated with a receiver (15) actuated by a fluid under pressure, - a conduit (16) for supplying fluid under pressure, to which the receiver (15) is connected, - an electrical pump (11, 10), to which the distributor (12) is connected, - a device (19) actuated by a measuring sensor (18) connected to the supply conduit of the receiver (15) and designed to monitor the electric motor (11) in comparison with the nominal value of an actuating means (20) of the receiver, characterised in that there is a differential valve (14) with a spring and with a pressure-drop limiting means controlled by the fluid pressure, this limiting valve acting to reduce the supply pressure of the receiver as a result of a reduction in the delivery of the pump.

Circuit for controlling, regulating and monitoring a fluid-flow

1 - The device comprises electrical motors for controlling a means of generating the brake pressure and is characterised by the fact that the electrical motors (15) assigned to each wheel (1,1',2,2') or pair of wheels (1,1'-2,2') on the same axle drive positive displacement pumps (16) generating the brake pressure on the slave cylinders (7) of the brakes (3 to 6).

Pressure-generating device for automotive vehicle breaking circuits

1 - Le Dispositif comporte des moteurs electriques de commande d'un moyen generateur de la pression de freinage et est caracterise par le fait que les moteurs electriques (15) associes a chaque roue (1,1′, 2,2′) ou paire de roues (1,1′-2,2′) d'un meme essieu entrainent des pompes volumetriques (16) generatrices de la pression de freinage aux cylindres recepteurs (7) des freins (3 a 6).

Didier Merletti

Papers

Pressure-generating device for braking circuits of motor vehicles

Circuit for controlling, regulating and monitoring a fluid-flow

Pressure-generating device for automotive vehicle breaking circuits

Dispositif générateur de pression pour circuits de freinage de véhicules automobiles

Circuit de commande, de regulation et de controle d'un debit de fluide