Electropneumatic valve assembly with self-locking safety valve
An electropneumatic valve assembly is for activating a parking brake function of an electropneumatic brake system. The valve assembly has a pilot control unit and a main valve unit configured to actuate a parking brake pressure at least at one spring-accumulator connection. The valve assembly has a service brake connection for receiving a service brake pressure and a safety valve. The safety valve, by receiving a safety control pressure, is switchable from a venting position, in which the safety valve connects the pilot control unit to a vent, to a supply position, in which the safety valve supplies the pilot control valve with reservoir pressure, the safety valve remaining in the supply position or switching to the venting position as a function of an actuated pressure. The service brake connection is connected to the safety valve control connection.
1 . An electropneumatic valve assembly for activating a parking brake function of an electropneumatic brake system of a commercial vehicle, the electropneumatic valve assembly comprising:
a pilot control unit configured to actuate a pilot control pressure as a function of an electronic parking brake signal;
a main valve unit configured to receive the pilot control pressure and to actuate a parking brake pressure at least at one spring-accumulator connection;
a service brake connection for receiving a service brake pressure;
a pneumatically switchable self-holding safety valve disposed upstream of said pilot control unit and having a safety valve control connection for receiving a safety control pressure and a safety valve holding circuit for receiving a pressure actuated by said pneumatically switchable self-holding safety valve or a pressure derived therefrom;
said pneumatically switchable self-holding safety valve, by receiving said safety control pressure, is switchable from a venting position, in which said pneumatically switchable self-holding safety valve connects said pilot control unit to a vent, to a supply position, in which said pneumatically switchable self-holding safety valve supplies said pilot control unit with reservoir pressure;
said pneumatically switchable self-holding safety valve being configured to remain in the supply position or switch to the venting position as a function of said actuated pressure received at said safety valve holding circuit; and,
said service brake connection being fluidically connected directly or indirectly to said safety valve control connection.
2 . The electropneumatic valve assembly of claim 1 , wherein said service brake connection is connectable to at least one of a front axle brake circuit and a rear axle brake circuit; and, said service brake pressure is at least one of a front axle brake pressure and a rear axle brake pressure of the commercial vehicle.
3 . The electropneumatic valve assembly of claim 2 , wherein said service brake connection is a release control connection; and, said service brake pressure is a release control pressure.
4 . The electropneumatic valve assembly of claim 3 further comprising a main control two-way valve configured to receive said pilot control pressure and said release control pressure and to provide a higher of said pilot control pressure and said release control pressure for said main valve unit; and, said main valve unit being configured to actuate said parking brake pressure as a function of said release control pressure or of said pilot control pressure.
5 . The electropneumatic valve assembly of claim 1 , wherein said service brake connection is a redundancy connection; and said service brake pressure is a redundancy brake pressure or a pressure derived from said redundancy brake pressure.
6 . The electropneumatic valve assembly of claim 1 , wherein said service brake connection is a trailer service brake connection; and, said service brake pressure is a trailer brake pressure.
7 . The electropneumatic valve assembly of claim 1 , further comprising an electropneumatic safety switch unit configured to actuate a safety pilot control pressure as a function of an electronic safety switch signal.
8 . The electropneumatic valve assembly of claim 7 further comprising a safety two-way valve configured to receive said safety pilot control pressure and said service brake pressure and to actuate a higher of said safety pilot control pressure and said service brake pressure as a safety control pressure.
9 . The electropneumatic valve assembly of claim 7 , wherein said safety switch unit is configured to receive the reservoir pressure, and in a first switched position, is configured to actuate said reservoir pressure as said safety pilot control pressure.
10 . The electropneumatic valve assembly of claim 8 , wherein said safety switch unit in a second switched position connects the safety two-way valve to a vent.
11 . The electropneumatic valve assembly of claim 9 , wherein said safety switch unit in a second switched position connects the safety two-way valve to a vent.
12 . The electropneumatic valve assembly of claim 1 , wherein said pneumatically switchable self-holding safety valve is configured to remain in said supply position if the actuated pressure applied to said safety valve holding circuit exceeds a first threshold value; and, said pneumatically switchable self-holding safety valve is configured to switch to said venting position if said actuated pressure applied to said safety valve holding circuit reaches or undershoots said first threshold value.
13 . The electropneumatic valve assembly of claim 12 , wherein said first threshold value is in a range from 200 kPa to 350 kPa.
14 . The electropneumatic valve assembly of claim 12 , wherein said first threshold value is in a range from 250 kPa to 315 kPa.
15 . The electropneumatic valve assembly of claim 1 , wherein said pneumatically switchable self-holding safety valve has a tension spring which preloads said pneumatically switchable self-holding safety valve to said venting position.
16 . The electropneumatic valve assembly of claim 1 , wherein said pilot control unit is a bistable pilot control unit.
17 . The electropneumatic valve assembly of claim 16 , wherein said bistable pilot control unit has a bistable electromagnetic magnet valve having at least one first permanent magnet.
18 . An electropneumatic brake system comprising:
an electropneumatic valve assembly for activating a parking brake function of the electropneumatic brake system of a commercial vehicle;
said electropneumatic valve assembly including a pilot control unit configured to actuate a pilot control pressure as a function of an electronic parking brake signal and a main valve unit configured to receive the pilot control pressure and to actuate a parking brake pressure at least at one spring-accumulator connection;
said electropneumatic valve assembly further including a service brake connection for receiving a service brake pressure;
said electropneumatic valve assembly further including a pneumatically switchable self-holding safety valve disposed upstream of said pilot control unit;
said pneumatically switchable self-holding safety valve having a safety valve control connection for receiving a safety control pressure and a safety valve holding circuit for receiving a pressure actuated by said pneumatically switchable self-holding safety valve or a pressure derived therefrom;
said pneumatically switchable self-holding safety valve, by receiving said safety control pressure, is switchable from a venting position, in which said pneumatically switchable self-holding safety valve connects said pilot control unit to a vent, to a supply position, in which said pneumatically switchable self-holding safety valve supplies said pilot control unit with reservoir pressure;
said pneumatically switchable self-holding safety valve being configured to remain in the supply position or switch to the venting position as a function of said actuated pressure received at said safety valve holding circuit;
said service brake connection being fluidically connected directly or indirectly to said safety valve control connection;
a service brake circuit having a brake module configured to provide said service brake pressure; and,
said brake module being fluidically connected to said service brake connection of said electropneumatic valve assembly.
19 . A vehicle, comprising the electropneumatic brake system of claim 18 .