Patent ID: 11938913
Assignee: ZF CV SYSTEMS GLOBAL GMBH
Field: Transport (Mechanical engineering)
Classification: CPC B | IPC B

Claim 7:
8. A power brake system (1.4) of a vehicle (2), comprising:
a pressure medium source (14),
a pressure-medium-operated primary brake system (30), which can be used as a service brake and steering brake system, the primary brake system (30) including at least one foot brake valve (36a, 36b) and at least two wheel brake cylinders (40a, 40b) arranged on opposite sides on a drive axle (8) and configured to be actuated independently of one another,
a pressure-medium-operated secondary brake system (50; 50′; 68; 100) operable independently of the primary brake system (30) and configured to be used at least as an auxiliary brake system, the secondary brake system (50; 50′; 68; 100) including a brake control valve (56; 70; 102) and at least one brake cylinder (62a, 62b; 62a′, 62b′; 82a, 82b), acting on wheel brakes of a vehicle axle (4, 8),
wherein the secondary brake system (50; 50′; 68; 100) is electronically controllable and includes:
the brake control valve (56; 70; 102) configured as a solenoid valve for setting a braking force of by feeding or removing pressure medium to or from the at least one brake cylinder (62a, 62b; 62a′, 62b′; 82a, 82b),
a pressure sensor (64; 90) connected to a working line (60; 60′; 74, 80) leading to the at least one brake cylinder (62a, 62b; 62a′, 62b′; 82a, 82b), and
an electronic brake control unit (46) for evaluating a pressure signal of the pressure sensor (64; 90) and for controlling the brake control valve (56; 70; 102) in accordance with a braking value signal (SBW);
wherein the brake control valve (102) is a 3/3-way proportional valve with a pressure medium inlet, a pressure medium outlet and a working port,
wherein the working port is continuously adjustable between a connection to the pressure medium outlet and to the pressure medium inlet,
wherein the pressure medium inlet is connected to the pressure medium source (14) via a foot brake valve (36a) arranged between two supply pressure lines (52, 104),
wherein the pressure medium outlet is connected to a pressure medium sink (16b),
wherein the working port is connected to the at least one brake cylinder (62a, 62b) via the working line (60),
wherein the pressure medium inlet is connected via an inlet pressure control line (106) to a first control pressure inlet (108), which acts on a first axial end of a valve spool (109) of the brake control valve (102),
wherein the pressure medium outlet is connected via an outlet pressure control line (112) to a second control pressure inlet (114) acting on a second axial end of the valve spool (109) of the brake control valve (102),
wherein a valve spring (110) acts on a first axial end of the brake control valve (102),
wherein an electromagnetic actuator (116) acts on a second axial end of the brake control valve (102), and
wherein, by energizing the actuator (116), a working pressure applied to the pressure medium outlet is reduced in comparison with a supply pressure applied to the pressure medium inlet.