Electropneumatic parking-brake valve unit

An electropneumatic parking-brake module comprising:

• an electropneumatic parking-brake valve unit including:
• at least a first supply connection for receiving supply pressure (pV) from a compressed air source;
• at least one spring brake connection for connecting to at least one spring brake cylinder of the vehicle;
• a parking-brake valve arrangement having at least a first bistable valve switchable between first and second switching states wherein a spring brake pressure (pF) can be controllable in dependence upon the switching state of said first bistable valve;
• a pneumatically switchable holding valve having a holding-valve connection whereat a first control pressure (p1) is provided and said pneumatically switchable holding valve being connected between said first supply connection and said first bistable valve;
• a deaerator;
• said pneumatically switchable holding valve being pretensioned under a spring load into a first switching position wherein said first bistable valve is connected to said deaerator;
• said first bistable valve being configured to switch into a second switching position when said first control pressure (p1) at said holding-valve connection exceeds a predetermined first threshold value;
• wherein said first bistable valve is connected to said first supply connection to receive said supply pressure (pV) in response to being switched into said second switching position;
• and,
• a multi-circuit protection valve unit connected upstream of said electropneumatic parking-brake valve unit in relation to the compressed air source wherein the multi-circuit protection valve unit provides the first control pressure (p1);
• and,
• wherein said first control pressure (p1) is controlled by an electrically switchable control valve which is part of the electropneumatic parking-brake valve unit or is arranged remotely therefrom.

A method for operating an electronically controlled pneumatic brake system of a vehicle including a utility vehicle, having an electropneumatic parking-brake valve unit including:

• at least a first supply connection for receiving supply pressure (pV) from a compressed air source;
• at least one spring brake connection for connecting at least one spring brake cylinder of the vehicle;
• and, a parking-brake valve arrangement having at least a first bistable valve, wherein a spring brake pressure (pF) can be controlled at the spring brake connection in dependence upon a switching of the first bistable valve;
• the method comprising:
• determining a fault in the brake system, which prevents switching of the first bistable valve;
• deaerating the first spring brake connection for stopping the vehicle;
• and,
• connecting at least two connections of the first bistable valve to a deaerator for preventing an output of the spring brake pressure (pF) after deaeration of the spring brake connection has taken place.