Failsafe valve unit, electronically controllable pneumatic brake system, vehicle, and method

An electronically controllable pneumatic brake system for a vehicle having a control unit, the electronically controllable pneumatic brake system comprising:

• a fail-safety valve unit for a failsafe brake function of the electronically controllable pneumatic brake system;
• said fail-safety valve unit having a main port configured to provide a first pressure and a failsafe brake port;
• said fail-safety valve unit further having a failsafe brake valve configured as a monostable valve, said failsafe brake valve being controllable by the control unit or by an external control unit;
• said failsafe brake valve being configured to pneumatically connect said main port and said failsafe brake port when in an open position to output a failsafe brake pressure at said failsafe brake port;
• wherein, in an event of at least one of a fault event, an electrical failure, and a diagnostic event of the control unit, said failsafe brake valve is configured to be in the open position and a failsafe braking operation of the vehicle is initiated through a provision of the failsafe brake pressure at said failsafe brake port by the brake system;
• said main port being pneumatically connected to a parking brake function in order to receive an output parking brake pressure as said first pressure;
• and,
• said fail-safety valve unit being arranged in a separate actuation branch and being pneumatically connectable via said failsafe brake port to at least one of a service brake cylinder, a service brake chamber, and an axle modulator in order to provide the failsafe brake pressure for said axle modulator in order to initiate the failsafe braking operation of the vehicle.

A method for operating a brake system having a fail-safety valve unit for a failsafe brake function of an electronically controllable pneumatic brake system for a vehicle, the method comprising:

• providing a signal for locking out a failsafe brake pressure, which takes effect for a failsafe braking operation, via a control unit or an external control unit;
• interrupting said providing the signal in at least one of an event of a fault event, an electrical failure, and a diagnostic event of the control unit and thus automatically ending the lock-out of the failsafe brake pressure to initiate the failsafe braking operation of the vehicle;
• and,
• wherein the failsafe brake pressure is a parking brake pressure output by a parking brake function for pressurizing parking brake cylinders.

A method for operating a brake system with a fail-safety valve unit for a failsafe brake function of an electronically controllable pneumatic brake system for a vehicle or a utility vehicle, the method comprising:

• providing a signal for locking out a failsafe brake pressure, which takes effect for a failsafe braking operation, via a control unit or an external control unit;
• interrupting said providing of the signal in at least one of a fault event, an event of an electrical failure, and a diagnostic event of the control unit and thus automatically ending the lock-out of the failsafe brake pressure to initiate the failsafe braking operation of the vehicle, wherein the failsafe braking operation has a diagnostic procedure including:
• ascertaining the failsafe brake pressure at a failsafe brake port;
• and,
• wherein, before said interrupting said providing of the signal, a demand is made for pressure to be output in a service brake system.