Locks: Description and Operation
Functional descriptionA. General
The central locking system is a single-pipe, actuating the elements by means of system pressure or vacuum (bi-pressure central locking system).
Central locking or unlocking is only possible from the driver's door by actuating the key or the safety button, with the door closed. The front passenger door, both rear doors, the trunk lid and the fuel tank flap are locked with vacuum and unlocked with pressure supplied from an electrically driven pump.
Advantages of the bi-pressure central locking system:
- Reduced load on the vacuum system by means of a separate supply pump.
- Simplification of the pipe system.
- Leak-proof requirements of the system are low
- Testing for repairs is simplified.
- The load on the elements is reduced as the system is pressureless when at rest.
B. Components
1. Supply pump
The supply pump generates a pressure or vacuum of approx. 0.5 bar within a time of approx. 2 seconds at 12 V battery voltage.
An electronic control ensures that the supply pump switches off after 25-60 seconds if heavy leaks exist in the system (safety switching time). After the supply pump has come to a stop, the pressure in the pipe system is discharged after 15-20 seconds.
The change of the pressure direction is controlled by the clockwise or anti-clockwise rotation of the motor and the pump. In this way it is ensured that always the last command will be carried out.
2. Switch in the driver's door
Continuous B+ (circuit 30) is present at the alternating switch input side. When actuating the switch via the door lock, B+ is connected to the output for the yellow control line during unlocking and to the output for the blue control line during locking.
3. Operating element.
A pneumatic connector is provided on the operating elements.
Operation and design of the operating elements in the doors. on the trunk lid and the fuel tank flap are identical. For locking they are supplied with vacuum and for unlocking with pressure.
The elements for the trunk lid and the fuel tank flap differ from those of the doors only with regard to their final detent position. For external identification, an upper part of these elements is in color. The door elements however are black. The final detent position is carried out by means of a spring in the door lock.