SCA Soft Close Automatic doors

With the SCA special equipment, a door is closed under controlled conditions by a sensor-controlled electric drive.

Brief description of components

CAS Car Access System

The CAS Car Access System control unit contains the functions of

• radio remote control,
  
• the ignition starter switch,
  
• the terminal control and
  
• the vehicle immobilizer.
  

It is also the gateway module between the data buses K-CAN SYSTEM and K-CAN PERIPHERALS.

The CAS controls all the higher-order functions of the central locking system.

DM door module

The door modules register the signals of the switches and sensors installed in the doors and control the drives installed in the doors. Information is received and sent via the K-CAN PERIPHERALS data bus. The door module detects

• the preliminary catch and the main catch positions of the rotary latch,
  
• opening of the door by the rotary latch signal,
  
• the standby and park positions of the SCA drive.
  

The door module controls the SCA drive with these input data.

SCA drive, door

The SCA drive is fitted in the system lock and closes the door. The SCA drive is activated by the door module control unit in the respective door module.

System lock

Two central locking drives are integrated into the system lock. This enables the lock mechanism to be moved into three locking positions. The positions are:

• Unlocked
  
• Locked
  
• Double-locked
  

Four switches (Hall sensors) are integrated in the system lock:.

• The rotary latch sensor signals to the door module control unit that the rotary latch is fully open (door open) or closed (door closed).
  
• The Unlocked sensor signals to the door module that the lock is unlocked.
  
• The locking pawl switch signals to the door module that the lock has reached the preliminary catch position.
  
• The SCA standby switch signals to the door module that the end position of the SCA drive in the rotary latch closed direction is reached.
  

Main functions

SCA functions and positions

The closing operation for the doors is performed by way of defined positions.

Defined positions

Door locks: The defined positions for closing are:

Preliminary catch

• The lock mechanism has caught in the door.
  
• The door is still open by a small gap but cannot be pulled open any more.
  

Main catch (park position)

• The door is closed.
  
• The door contact is actuated by means of the rotary latch.
  
• The lock mechanism and the SCA drive are in the end position.
  
• The door is fully closed.
  

SCA drive: The defined positions for closing are:

Park position:

• The door,
  
• the door contact and
  

• the rotary latch are closed.
  
• The lock mechanism is in the main catch position.
  

Standby position

• The door,
  
• the door contact and
  
• the rotary latch are open.
  

Door closing

When the door is slowly closed, the locking pawl sensor signals to the door module control unit when the preliminary catch position is reached. The door module control unit activates

• the SCA drive and
  
• the door is pulled into the main catch position (park position).
  

The SCA drive remains in the main catch position (park position).

When quickly closed (slamming shut), the door travels very swiftly through the preliminary catch position to the main catch position. A closing operation is therefore not initiated by the SCA. The SCA drive remains in the standby position although

• the door,
  
• the door contact and
  
• the rotary latch are closed and
  
• the lock mechanism is in the main catch position.
  

The SCA is not activated the next time the door is opened.

Door opening

When the door is opened, the SCA drive receives from the door contact the signal to move into the standby position. From the standby position, the rotary latch reaches after half a turn the main catch position (park position) the next time the door is pulled shut.

Deactivating SCA drive

If the control system fails to detect that the standby or park position has been reached,

• the system deactivates the SCA drive after 5 seconds.
  
• An entry is made in the fault memory.
  

The functional sequence starts again when the preliminary catch position or door contact is signalled.

Anti-repeat circuit

An anti-repeat circuit prevents electronic components in the control unit from overheating. The anti-repeat circuit permits a maximum of 15 activations in succession.