Monostable and fault-tolerant parking brake valve assembly

A parking brake valve assembly for an electronically controllable pneumatic braking system of a vehicle, the parking brake valve assembly comprising:

• a first compressed air path receiving a first or second supply pressure (pV, pV1, pV2) and having a first monostable valve unit for providing a first parking brake pressure (pF1);
• a second compressed air path receiving said first or second supply pressure (pV, pV1, pV2) and having a second monostable valve unit for providing a second parking brake pressure (pF2);
• a first shuttle valve having:
• a first shuttle valve port with said first compressed air path and receiving said first parking brake pressure (pF1);
• a second shuttle valve port with said second compressed air path and receiving said second parking brake pressure (pF2);
• and, a third shuttle valve port connectable to a spring brake cylinder;
• said first shuttle valve being configured to respectively output the higher of said first parking brake pressure (pF1) and of said second parking brake pressure (pF2) to said third shuttle valve port;
• said first monostable valve unit having a first switching valve and a second switching valve mutually connected in a pressure conducting manner so as to cause said first parking brake pressure (pF1) to be output only when said first and second switching valves are energized;
• and,
• wherein said second monostable valve unit has a third switching valve and a fourth switching valve mutually connected in a pressure-conducting manner so as to cause said second parking brake pressure (pF2) to be output only when said third and fourth switching valves are energized.

A parking brake valve assembly for an electronically controllable pneumatic braking system of a vehicle, the parking brake valve assembly comprising:

• a first compressed air path receiving a first or second supply pressure (pV, pV1, pV2) and having a first monostable valve unit for providing a first parking brake pressure (pF1);
• a second compressed air path receiving said first or second supply pressure (pV, pV1, pV2) and having a second monostable valve unit for providing a second parking brake pressure (pF2);
• a first shuttle valve having:
• a first shuttle valve port with said first compressed air path and receiving said first parking brake pressure (pF1);
• a second shuttle valve port with said second compressed air path and receiving said second parking brake pressure (pF2);
• and, a third shuttle valve port connectable to a spring brake cylinder;
• said first shuttle valve being configured to respectively output the higher of said first parking brake pressure (pF1) and of said second parking brake pressure (pF2) to said third shuttle valve port;
• said first compressed air path for ventilating the first shuttle valve port and said second compressed air path for ventilating said second shuttle valve port being respectively connected to a single, ventilating valve;
• and,
• said ventilating valve having a pressure limiter and a throttle which is arranged parallel to said pressure limiter and permits overflowing of said pressure limiter.

An electronically controllable pneumatic braking system for a vehicle including utility vehicle, the electronically controllable pneumatic braking system having first and second modules for performing respective functions different from each other, the pneumatic braking system comprising:

• a first electronic control unit (ECU1) and a second electronic unit (ECU2), wherein said first and second electronic control units (ECU1, ECU2) are configured in such a manner that they can at least partially replace one another in the event of a fault;
• a parking brake valve assembly including:
• a first compressed air path receiving a first or second supply pressure (pV, pV1, pV2) and having a first monostable valve unit for providing a first parking brake pressure (pF1);
• a second compressed air path receiving said first or second supply pressure (pV, pV1, pV2) and having a second monostable valve unit for providing a second parking brake pressure (pF2);
• a first shuttle valve having:
• a first shuttle valve port with said first compressed air path and receiving said first parking brake pressure (pF1);
• a second shuttle valve port with said second compressed air path and receiving said second parking brake pressure (pF2);
• and, a third shuttle valve port connectable to a spring brake cylinder;
• said first shuttle valve being configured to respectively output the higher of said first parking brake pressure (pF1) and of said second parking brake pressure (pF2) to said third shuttle valve port;
• wherein said first electronic control unit (ECU1) is connected to said first monostable valve unit for providing first switching signals (S1) thereto;
• said second electronic control unit (ECU2) is connected to said second monostable valve unit for providing second switching signals (S2) to the second monostable valve unit;
• said first electronic control unit (ECU1) and said second electronic control unit (ECU2) being assigned independently of each other to corresponding ones of said first and second modules as respective control units thereof;
• a first voltage source;
• a second voltage source;
• said first monostable valve unit being supplied by said first voltage source;
• said second monostable valve unit being supplied by said second voltage source;
• and,
• said first and second voltage sources being independent of each other so as to ensure that, as long as one of said first electronic control unit (ECU1) and said second electronic control unit (ECU2), or one of said first and second voltage sources functions correctly, at least one of the first parking brake pressure (pF1) and the second parking brake pressure (pF2) is output such that, when one of said first electronic control unit (ECU1) and said second electronic control unit (ECU2) is functional, the parking brake pressure (pF1, pF2) is output at the third shuttle valve port.