Electric motor for the fully automatic trailer tow hitch

The fully automatic trailer tow hitch is available in 2 versions (manufacturers: Oris and Westfalia).

Fully automatic trailer tow hitch, version from manufacturer Westfalia 

The electric motor of the fully automatic trailer tow hitch consists of the following components:

• Direct current motor
• Hall effect sensor
• Reduction gearset
• Pivoting mechanism with gate for guiding the ball head

The DC motor drives a spindle via the reduction gear. The rotational movement of the spindle, with the aid of the gate, pivots the ball head out and in using the swivelling mechanics. The gate determines the movement of the ball head when it is pivoting in and out.

A hall effect sensor is integrated into the drive system. The entire pivoting angle of the ball head is monitored with the aid of the Hall effect sensor. In parallel to the hall effect sensor signals, the trailer module (AHM) measures the current required for the swivel motion. If the permissible power consumption of the direct current motor is exceeded during fully automatic pivoting out or in, or no hall effect sensor signals are emitted, the ball head's swivel motion is halted. The ball head is pivoted back a short way in the opposite direction (reversed).

To ensure that the trailer tow hitch remains pivoted out in the end position, the direct current motor is periodically briefly activated in the direction of the end stop.

Cyclical readjustment of the pivoted-out ball head can result in the ball head becoming mechanically jammed in this end position. In this event, the ball head can be freed from the end stop by the breakaway function.

The following graphic shows the fully automatic trailer tow hitch (manufacturer Westfalia) using the example F11.

Fig 1: Identifying Trailer Tow Hitch With Cover

Courtesy of BMW OF NORTH AMERICA, INC.

Fully automatic trailer tow hitch, version from manufacturer Oris 

The electric motor of the fully automatic trailer tow hitch consists of the following components:

• Direct current motor
• Hall effect sensor
• 2 Switch
• Reduction gearset
• Swivelling mechanics

The direct current motor drives the swivelling mechanics via the reduction gear. Using the swivelling mechanics, the ball head is pivoted out or in.

A hall effect sensor and 2 switches are integrated into the electric motor. The entire pivoting angle of the ball head is monitored with the aid of the Hall effect sensor. In parallel to the hall effect sensor signals, the trailer module (AHM) measures the current required for the swivel motion. If the permissible power consumption of the direct current motor is exceeded during fully automatic pivoting out or in, or no hall effect sensor signals are emitted, the ball head's swivel motion is halted. The ball head is pivoted in the opposite direction to the end position (reverse).

Using both switches, the swivel motion and the operating position of the ball head are detected.

The trailer tow hitch is locked in operating position. For safety, the clearance of the ball head is ascertained in the operating position. For this purpose, the direct current motor is driven erratically for a short time in the direction of the end stop. The control unit determines the ball head clearance from the hall effect sensor signals and the power consumption of the direct current motor.

Irregular readjustment of the pivoted out ball head can lead to the ball head mechanically locking in this end position (trailer tow hitch in operating position). In this event, the ball head can be freed from the end stop by the breakaway function.

The following graphic shows the fully automatic trailer tow hitch (manufacturer Oris) using the example F15.

Fig 2: Identifying Hall Effect Sensor

Courtesy of BMW OF NORTH AMERICA, INC.