Patent ID: 6290306
Filing Date: 2001-09-18
Classification: B60T,Y10S

Abstract:
A hydraulic vehicle brake system (10) for braking by brake pedal actuation and for automatic braking, which comprisesa master cylinder (12), which has a housing (15), a bore (16) in the housing and a first displaceable piston (17) in the bore, the first piston being displaceable as a function of a depression of a brake pedal (11); a second piston (18) on a side of the first piston (17) away from the brake pedal (11); a first pressure chamber (19), between the first and second piston (17, 18), which communicates with a first connection (20) of the master cylinder, embodied on the housing (15), and a second connection (21); and, adjoining the second piston (18) on a side away from the first pressure chamber (19), a second pressure chamber (22) of the master cylinder with a third connection (23), embodied on the housing (15), and a fourth connection (24), wherein when the brake pedal (11) is depressed, there is no hydraulic communication between the first and second connections (20, 21) or between the third and fourth connections (23, 24);a supply container (14) for pressure fluid, wherein the supply container (14) is assigned to the first and third connections (20, 23) of the master cylinder (12);a valve means (34), disposed in a region of the first connection (20) of the master cylinder (12), by means of which upon automatic braking a pressure of the pressure fluid on flowing through the first pressure chamber (19) to the supply container (14) is limited;a pump (84), which has a suction connection (86), communicating with the supply container (14), and a pressure connection (88), communicating with the second connection (21) of the master cylinder (12), for aspirating pressure fluid from the supply container (14) and pumping the fluid to the second connection (21) of the master cylinder (12);a first brake circuit (I) connected to the second connection (21) of the master cylinder (12), and a second brake circuit (II), connected to the fourth connection (24) of the master cylinder (12), wherein each brake circuit (I, II) has a plurality of wheels associated with wheel brake cylinders (56, 57, 70, 71), and valve assemblies (58, 59, 72, 73) for brake pressure modulation in the wheel brake cylinders (56, 57, 70, 71);a control unit (93) for performing automatic braking operation with an activation of the pump (84),the valve means (34) is actuatable by the pressure of the pump (84) upon automatic braking, and at low pump pressure throttles the flow through the first pressure chamber (19) of the master cylinder (12) to the supply container (14) for pressure fluid and, at a pump pressure elevated with respect thereto limits this pressure,in which the pump (84) is embodied as a low-pressure pump;that the valve assemblies (58, 59, 72, 73) for the brake pressure modulation in both brake circuits (I, II) are each assigned one high-pressure pump (64, 75);that in a brake circuit (I) the high-pressure pump (64) is connected on an intake side, through a multiway valve (65), to the second connection (21) of the master cylinder (12), and in the circuit (II) the high-pressure pump (75) is connected on the intake side through a multiway valve (76) to the fourth connection (24) of the master cylinder (12);and that when the brake pedal (11) is not actuated, in automatic braking operation, the low-pressure pump (84) furnishes charge pressure to the high-pressure pumps (64, 75).