Method and device for operating a power steering system

Abstract

The invention relates to a method and to devices for operating a power steering system (10) of a motor vehicle, wherein a motor torque (26) applied by an electric motor (16) is superposed on a specified manual torque (24) in a superposing unit (14), wherein a beginning freezing of the power steering system (10) is detected by means of suitable measures, such as an evaluation of rotational speed patterns of the electric motor (16), and wherein the electric motor (16) is controlled by means of an oscillating control signal in order to avoid the freezing of the power steering system (10), wherebyan oscillating application of a shaking torque (26*) to the power steering system (10) is effected, which shaking torque is applied by the electric motor (16). According to the invention, instead ofan oscillating control signal (S#) that has a uniform amplitude (a0) that acts in continuous time spans (T0), a control signal (S*) that has first time spans (T1) in which the control signal (S*) hasan increased amplitude (a1) and second time spans (T2) in which the control signal (S*) has no amplitude or a reduced amplitude (a2) is now generated, whereby the shaking torque (26*) applied by the electric motor (16) can be produced with an increased maximum torque (M*) in the first time spans (T1), without thermal overloading of the electric motor (16).

Description

technical field [0001] The invention relates to a method for operating a power steering system and a device for carrying out the method. Background technique [0002] In power steering systems of motor vehicles, a motor torque is usually superimposed by means of an electric motor on a manual torque applied by the driver. This superimposition is usually carried out by means of a superposition unit in the form of a superposition gear. Since power steering is generally used outdoors, it is exposed to external influences, in particular environmental influences and temperature influences. As a result, the functional effectiveness of the steering mechanism can be impaired. In particular, a possible freezing of the power steering due to ingress of water presents a particular problem here. [0003] Methods are known by which freezing of the power steering system is detected and countermeasures are taken. DE 10 2010 002 803 A1 discloses a method for operating a power steering sys...

AI Technical Summary

Problems solved by technology

As a result, the driver's injuries can be reduced; however, the relatively high frequency has the effect that the actually relatively high and therefore inert mass of the power steering system cannot vibrate freely enough

Furthermore, the oscillating motor current must not have too high an amplitude, since otherwise overheating of the electric motor and / or overheating of the control or controller would be encountered

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