Patent ID: 11970146
Assignee: ZF CV SYSTEMS EUROPE BV
Field: Transport (Mechanical engineering)
Classification: CPC B | IPC B

Claim 0:
1. An electronically controllable secondary brake system (46, 46′) of a vehicle (2), the secondary brake system operable as both a parking brake system and an auxiliary brake system, the secondary brake system operated by pressure medium and comprising:
spring brake cylinders (68a, 68b) arranged on wheel brakes of at least one vehicle axle (8);
a directly or indirectly electronically controllable brake control valve (56, 56′), an electronic brake control unit (48) that controls the brake control valve (56, 56′) in a manner that is dependent on the current value of a brake value signal (SBW),
wherein the brake control valve is a 3/3-way proportional valve with a pressure medium inlet, a pressure medium outlet, and a working connector,
wherein the working connector is adjustable continuously between a connection to the pressure medium outlet and to the pressure medium inlet,
wherein the pressure medium inlet is connected via a supply line (52) to a pressure medium source (14),
wherein the pressure medium outlet is connected to a pressure medium sink (16b), and
wherein the working connector is connected via a working line (60, 66) to the spring brake cylinders (68a, 68b),
wherein a controllable check valve (62), which shuts off in the direction of the brake control valve (56, 56′), is arranged in the working line (60)
wherein brake force of the spring brake cylinder (68a, 68b) is reduced by the brake control valve (56, 56′) by way of a feed of pressure medium and
wherein the brake force of the spring brake cylinder (68a, 68b) is increased by the brake control valve (56, 56′) by way of a discharge of pressure medium,
wherein the brake control valve (56) is a solenoid valve, an electromagnet of which is actuated directly by the brake control unit (48) via an electric control line (58), and wherein the working connector of said brake control valve (56) is connected to the pressure medium outlet in the non-energized state and is connected in an unthrottled manner to the pressure medium inlet in the maximum energized state.