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AssigneeRobert Bosch GmbH
InventorsWolf-Dieter Jonner, Ortwin Engfer, Anton Van Zanten, Jurgen Binder, Martin Pfau, Eberhardt Schunck, Andreas Kaessmann, Juergen Hachtel, Ulrich Gottwick, Michael Schubert
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A hydraulic vehicle brake system in which normal service brake operation can be carried out by using external hydraulic energy, and in the event of a lack of external hydraulic energy, auxiliary brake operation by muscle power is possible, with a hydraulic transmission that comes from a master cylinder that can be actuated by means of the brake pedal. The external hydraulic energy is stored, for example, in an accumulator with a gas buffer, which can lead to a gas content in the hydraulic fluid for the service brake operation. The system includes a dual-circuit master cylinder associated with those wheel brakes of a vehicle axle that make a higher contribution to the vehicle deceleration and at the same time, cylinder/piston devices are installed between these wheel brakes and their associated service brake valves for the purpose of preventing hydraulic fluid from getting into these wheel brakes from the external energy source. The advantage is that neither gas nor air is carried into the wheel brakes where it could lead to the formation of bubbles in the event of a pressure drop and would be disadvantageous for an auxiliary brake operation by the master cylinder. The cylinder/piston devices increase the operational safety of the vehicle brake system when braking by muscle power.
A hydraulic brake system for a vehicle comprising wheel brakes for four wheels, in which the wheels are distributed on a first and a second vehicle axle, comprising an external hydraulic energy source, and has electrically controllable service brake valve devices disposed between said energy source and the wheels, a first braking power transmitter (38) that is actuated by a brake pedal, for carrying out service brake operations by operation of the service brake valve devices, a dual-circuit master cylinder, said master cylinder is actuated by the brake pedal and is intended for carrying out an auxiliary brake operation by muscle-powered energy via said brake pedal, wherein between the master cylinder and wheel brakes that are supplied from said master cylinder, a normally open operation mode reversing valve (17, 18) is disposed in each brake circuit, said reversing valve is switched into a closed position for the service brake operation, and wherein at least the service brake valve devices are controlled by a controlling and regulating device, a cylinder/piston device (52, 53) is interposed between the wheel brakes (5, 6) of the vehicle axle that is designed for a greater braking contribution to the vehicle braking and the associated, electrically controllable service brake valve devices (27, 28), and that the wheel brakes (5, 6) designed for the greater braking contribution to the vehicle braking are connected to the operation mode reversing valves (17, 18) associated with the two brake circuits of the master cylinder 9, a normally closed volume diversion valve (63, 64) is connected to the wheel brakes (5, 6) which are connected to the cylinder/piston device (52, 53), that said volume diversion valves (63, 64) are connected to a reservoir (14) of the external hydraulic energy source (19) and are opened by the controlling and regulating device (37) in the event that a brake pressure reduction that is controlled by service brake valves (27, 28) or a wheel brake slip reduction proves to be insufficient.
A hydraulic brake system for a vehicle comprising wheel brakes for four wheels, in which the wheels are distributed on a first and a second vehicle axle, comprising an external hydraulic energy source and electrically controllable service brake valve devices disposed between said energy source and the wheels, a first braking power transmitter (38) that is actuated by a brake pedal, for carrying out service brake operations by operation of the service brake valve devices, a dual-circuit master cylinder, said master cylinder is actuated by the brake pedal and is intended for carrying out an auxiliary brake operation by muscle-powered energy via said brake pedal, wherein between the master cylinder and wheel brakes that are supplied from said master cylinder, a normally open operation mode reversing valve (17, 18) is disposed in each brake circuit, said reversing valve is switched into a closed position for the service brake operation, and wherein at least the service brake valve devices are controlled by a controlling and regulating device, a cylinder/piston device (52, 53) is interposed between the wheel brakes (5, 6) designed for the greater braking contribution to the vehicle braking and the associated electrically controllable service brake valve devices (27, 28), and the wheel brakes (5, 6) designed for the greater braking contribution to the vehicle braking are connected to the operation mode reversing valves (17, 18) associated with the two brake circuits of the master cylinder 9, a first brake pressure compensation line (44) is disposed between the service brake valve devices (25, 26) and the wheel brake cylinders (3, 4) of one vehicle axle, said first brake pressure compensation line has a normally open brake pressure compensation valve (45) built into the first brake pressure compensation line, and a second brake pressure compensation line (46) is disposed between the service brake valves (27, 28) and the cylinder/piston devices (52, 53) that are connected with another vehicle axle, said second brake pressure compensation line has a normally open brake pressure compensation valve (47) built therein and that each connection of the first and second brake pressure compensation valve (45, 47) is connected to a normally open first or second relief valve (49, 51), wherein the normally open first and second relief valves (49, 51) are connected by means of at least one relief line (48, 50) to the reservoir (14) of the external hydraulic energy source (19) and can be closed for the service brake operation.
Dependencies are inferred from the claim text.