Electropneumatic parking brake unit with a self-holding function in the event of a fault

A method for controlling a parking brake function of a commercial vehicle having an electropneumatic brake system, the method comprising:

• electromagnetically switching an electromagnetic solenoid valve having at least one first permanent magnet from an air-purging position into an air-supplying position for modulating a parking brake pressure at least at one spring accumulator connection for supplying air to at least one spring-loaded brake cylinder;
• at least one of confining a pilot pressure modulated by the electromagnetic solenoid valve and holding the electromagnetic solenoid valve in the air-purging position;
• and,
• when a supply pressure provided to the electromagnetic solenoid valve drops below a first threshold value:
• pneumatically or mechanically switching the solenoid valve into the air-purging position.

A method for controlling a parking brake function of a commercial vehicle having an electropneumatic brake system, wherein the electropneumatic brake system includes an electropneumatic valve arrangement having a pilot control unit and a main valve unit, the pilot control unit includes an electromagnetic solenoid valve having at least one first permanent magnet, wherein the pilot control unit is configured to modulate a pilot pressure in dependence upon an electronic parking brake signal, the main valve unit is configured to receive the pilot pressure and modulate a parking brake pressure at least at one spring accumulator connection in dependence upon the pilot pressure, the electromagnetic solenoid valve has a safety control connection for receiving a safety control pressure, the electromagnetic solenoid valve is configured to supply the pilot control unit with a supply pressure or connect the pilot control unit to an air-purging in dependence on the safety control pressure, wherein the safety control pressure is a pressure modulated by the electromagnetic solenoid valve or a pressure derived from the electromagnetic solenoid valve, the method comprising:

• electromagnetically switching the electromagnetic solenoid valve from an air-purging position into an air-supplying position for modulating the parking brake pressure at least at one spring accumulator connection for supplying air to at least one spring-loaded brake cylinder;
• at least one of confining the pilot pressure modulated by the electromagnetic solenoid valve and holding the electromagnetic solenoid valve in the air-purging position;
• and,
• when the supply pressure provided to the electromagnetic solenoid valve drops below a first threshold value:
• pneumatically or mechanically switching the solenoid valve into the air-purging position.