Reversible Electromotive Automatic Reel, Left And Right

Reversible Electromotive Automatic Reel, Left And Right


The reversible electromotive automatic reel offers the driver and the front passenger additional protection and comfort.

The reversible electromotive automatic reel system includes the following functions:
- Removal of the belt slack after buckling up so that the seat belt lies optimally against the driver's resp. front passenger's body.
- Stabilization of the seat position in a critical driving situation by pretensioning the seat belt for optimizing the restraint system.

Brief component description
The reversible electromotive automatic reel is a mechatronic system. The reversible electromotive automatic reel consists of a automatic reel, electric motor with gearbox and an integrated control unit.

The following components are described:
- Reversible electromotive automatic reel control unit (REMAFA and REMABF)
- Drive reversible electromotive automatic reel

The following graphic shows the reversible electromotive automatic reel and the seat belt.







Reversible electromotive automatic reel control unit (REMAFA, REMABF)
The control unit is integrated into the reel. There is one control unit each for the driver's side and the front passenger side. The reversible electromotive automatic reel is mounted in the area of the B-pillar with a retaining plate, which is adapted to the respective vehicle type. For convertibles, the reversible electromotive automatic reel is installed under the respective seat. The voltage supply of the control unit occurs via Terminal 30B. The ground connection occurs via Terminal 31. The control unit is connected with the PT-CAN in the vehicle. After evaluation of various signals and messages, the control unit recognizes whether the seat belt has to be pretensioned. For example, the belt slack is thus removed after buckling up depending on the speed signal. To do this, the control unit activates the respective reversible electromotive automatic reel.

Drive reversible electromotive automatic reel
The drive of the reversible electromotive automatic reel primarily consists of the following parts:
- Electric motor
- Control unit
- Gear with clutch (the clutch sets up the connection to the reel mechanism)
- Automatic reel (mechanical function)

The voltage supply of the electric motor occurs via Terminal 30. The ground connection occurs via Terminal 31. The electric motor is supplied with current (direction of motor rotation "tension seat belt") and moves an output wheel in the clutch by means of a gear. In the clutch, locking pawls move out and enter the clutch case. The clutch case is firmly connected to the drive shaft of the reel mechanism. This rolls up the seat belt.

To open the clutch, the direction of rotation of the electric motor must be briefly changed (opposite motor direction of rotation "tension belt"). If the connection between the electric motor and reel mechanism is interrupted, the reel mechanism works in the same way as a conventional mechanical reel mechanism.

There are two hall effect sensors on the circuit board which detect the rotational movement of a magnetic disc. The magnetic disc is integrated into the housing of the control unit and is driven by the coil of the automatic reel. This monitors the pullout of the seat belt. The direction of rotation of the electric motor can be changed through a corresponding activation via the control unit.

The following graphic shows the design of the reversible electromotive automatic reel.







System functions
When a seat belt is put on, the control unit activates the respective reversible electromotive automatic reel one time over a specific period. Above an encodable speed (currently 10 Km/h), the seat belt strap is rolled up by the drive thus removing the belt slack.

In critical driving situations or in the event of a possible accident, the control unit also activates the drive. An algorithm calculates the driving condition and can issue the request for belt tensioning. The duration is set in such a way that the drive is activated by the control unit until a collision occurs or until a critical driving situation ends.

For calculating whether a critical driving situation exists, for example, vehicle oversteering, both control units (REMAFA and REMABF) use the data from the following systems:
- DME (Digital Engine Electronics) or DDE (Digital Diesel Electronics)
DME (Digital Engine Electronics) or DDE (Digital Diesel Electronics) supplies the signals of the pedal sensor position.
- Integrated chassis management (ICM)
The Integrated Chassis Management (ICM) makes information about the driver's choice and about the dynamic handling characteristics status available to the systems in the entire vehicle.
- Dynamic stability control (DSC)
The Dynamic Stability Control (DSC) supplies information about the brake pressure.
- Crash Safety Module (ACSM)
The Crash Safety Module (ACSM) sends a message with the status of the seat belt buckle contacts. The request for tensioning the seat belt occurs from the Crash Safety Module (ACSM).
- Camera-based driver support systems (KAFAS)
The camera-based driver support systems (KAFAS) supply the signals of the lane departure warning and object detection. The request for tensioning the seat belt occurs through the camera-based driver support system (KAFAS).
- Active Cruise Control (ACC)
The Active Cruise Control (ACC) processes the signals about distance and speed about objects moving away from the vehicle in front of the vehicle and sends these to the Integrated Chassis Management (ICM). The request for tensioning the seat belt is sent via the PT-CAN to the respective reversible electromotive automatic reel (REMAFA and REMABF) via the Integrated Chassis Management (ICM).

The following graphic shows the system as example in the F10:







Notes for Service department

General notes
The drive of the reversible electromotive automatic reel can be activated via the diagnosis system.

Failure of the drive of the reversible electromotive automatic reel will be accompanied by the following:
- Fault code entry in the control unit of the reversible electromotive automatic reel, left (REMAFA control unit)
- Fault code entry in the control unit of the reversible electromotive automatic reel, right (REMABF control unit)
- A failure of a control unit has no effect on the restraining function of the seat belt.

We can assume no liability for printing errors or inaccuracies in this document and reserve the right to introduce technical modifications at any time.