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US 7,243,570 B2Granted
Power-assisted steering with electric motor locking device
AssigneeZF Lenksysteme GmbH
InventorsThomas Kuehnhoefer, Rainer Biegert
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AssigneeZF Lenksysteme GmbH
InventorsThomas Kuehnhoefer, Rainer Biegert
Estimating the term…
A power-assisted steering with a superimposing gear mechanism enables safe steering behavior independently of the type of transmission used. A mechanical lock is mounted at a part of the transmission, preferably at the screw itself. In the event of a malfunction, this lock acts in addition to the deactivation of an electric motor and reliably prevents it from rotating further in that a locking pin engages elongated hole-shaped grooves. The shape of the grooves has the advantage that the locking pin need not be positioned very precisely. Allowances are thus made for installation tolerances. The development of noise is also reduced since it is very improbable that the locking pin, before it is locked in one of the grooves, would first of all come into contact with an intermediate bridge and thus produce an unpleasant clacking noise. In addition, a diagnostic circuit may be provided which checks the function of the lock before the vehicle is started up.
Power-assisted steering comprising an electric motor and a superimposing gear mechanism which superimposes a correction angle on the steering angle specified at the steering handling device of a vehicle, the motor having a rotor moving a mechanical transmission part of the superimposing gear mechanism, the electric motor having a mechanical lock which, in addition to electrically deactivating the electric motor, immobilizes the mechanical transmission part of the superimposing gear mechanism at least in situations affected by a malfunction and secures it to prevent movement, the transmission part being provided with elongated hole-shaped grooves which are engaged by a pin of the mechanical lock and the lock is connected with a diagnostic circuit which checks the electric motor and the lock for a defect-free locking function before the lock is unlocked.
Dependencies are inferred from the claim text.