Compressed air supply installation for operating a pneumatic installation, method and vehicle

1. A compressed air supply installation for operating a pneumatic installation in a pneumatic system of a vehicle, the compressed air supply installation comprising:

a compressed air supply;

a compressed air port to the pneumatic installation;

a vent port to a venting environment;

a pneumatic main line between the compressed air supply and the compressed air port, the pneumatic main line having an air dryer;

a vent valve arranged in the pneumatic main line, the vent valve being a first pilot valve having a pilot control port;

a compressor having at least one compressor stage;

a second pilot valve and a pneumatic pilot control channel which that pneumatically connects the second pilot valve to the pilot control port of the first pilot valve,

wherein a pressure-holding pneumatic valve device is connected to the pilot control port of the first pilot valve and is configured to provide, during venting of the pneumatic system and independently of a pressure in the main pneumatic line, a control pressure for the pilot control port of the first pilot valve,

and

wherein the pressure-holding pneumatic valve device is configured to be pneumatically connected to a pressure accumulator via a feed line, and

wherein the pressure-holding pneumatic valve device has a selection valve configured for autonomous connection of the pilot control port of the first pilot valve to the feed line in a first operating position and to the pneumatic main line in a second operating position, such that a line, selected from the feed line and the pneumatic main line, in which a relatively higher pressure prevails is connected to the pilot control port of the first pilot valve and a line, selected from the feed line and the pneumatic main line, in which a relatively lower pressure prevails is blocked from the pilot control port of the first pilot valve.

2. The compressed air supply installation as claimed in claim 1 , wherein the feed line is configured to be pneumatically connected to the compressor for charging the compressor.

3. The compressed air supply installation as claimed in claim 1 , wherein the selection valve is configured as a changeover valve.

4. The compressed air supply installation as claimed in claim 1 , wherein the selection valve has an adjustable preferred position such that, with equal pressures at the first input and the second input of the selection valve, the input at the adjustable preferred position is connected to an output of the selection valve.

5. The compressed air supply installation as claimed in claim 4 , wherein the selection valve has a spring configured to predefine the adjustable preferred position.

6. The compressed air supply installation as claimed in claim 1 , wherein the compressor has a first low-pressure compressor stage and a second high-pressure compressor stage.

7. The compressed air supply installation as claimed in claim 1 , wherein the feed line is configured to be pneumatically connected via a charging line to the compressor for charging the compressor.

8. The compressed air supply installation as claimed in claim 1 , wherein the pressure-holding pneumatic valve device is fully or partly integrated in the compressed air supply installation.

9. A method for operating a compressed air supply installation, wherein the compressed air supply installation is configured to operate a pneumatic installation in a pneumatic system of a motor vehicle, and has a pressure-holding pneumatic valve device, the method comprising:

compressing air to provide compressed air;

supplying the pneumatic installation and/or a pressure accumulator and/or a gallery with the compressed air;

operating the pneumatic installation;

venting the pneumatic system via a vent valve configured as a pilot valve and having a pilot control port,

wherein the pressure-holding pneumatic valve device is connected to the pilot control port and holds the pilot control port under control pressure during venting of the pneumatic system and independently of a pressure in the pneumatic main line,

wherein the pressure-holding pneumatic valve device is configured to be pneumatically connected to a pressure accumulator via a feed line, and

wherein the pressure-holding pneumatic valve device has a selection valve for autonomous connection of the pilot control port to the feed line or the pneumatic main line, such that a line, selected from the feed line and the pneumatic main line, in which a relatively higher pressure prevails is connected to the pilot control port, and a line, selected from the feed line and the pneumatic main line, in which a relatively lower pressure prevails is blocked from the pilot control port.

10. A vehicle with a pneumatic system and a compressed air supply installation as claimed in claim 1 .