Zf Lenksysteme Gmbh

Rainer Biegert

Thomas Kuehnhoefer

A method for aligning a steer angle, which is determined continuously in a processor for controlling a steering system, with a second steer angle which is measured continuously by a sensor of the steering system, the steer angles varying over time in such a way as to deviate negatively and positively from a neutral value. A first time profile of the varying first steer angle is monitored continuously, and a second time profile of the varying second steer angle is monitored continuously. If no alignment of the first steer angle with the second steer angle has yet been carried out, the first steer angle is set to the present value of the second steer angle. If at least one alignment of the first steer angle with the second steer angle has already been carried out previously, and if a change of sign occurs in the first profile, the first steer angle is varied by a corrective value which is determined as a function of a hysteresis occurring in the second profile. The disclosure is particularly suitable for use in a control unit of an electric power steering system.

Method and device for aligning a determined steer angle with a measured steer angle

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.

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Boehmenkirch, Germany

Rainer Biegert