| 摘要 |
The invention relates to a power steering gear with a differential drive. In conventional power steering, malfunctioning of the electric motor (servomotors) or the control thereof can lead to unwanted overlappings of steer-angle changes, which influences the handling performance of the vehicle to an unpleasant or dangerous degree. Differential gears already exist, in which the servomotor is coupled by means of a worm wheel gear, which has a self-locking mechanism that somewhat counteracts this problem. This effect is not sufficient. Other types of gears, such as screw gears, do not have such a self-locking effect. The invention provides a clearly improved solution which enables safe steering performance that is independent of the type of gear used. To this end, a mechanical locking device (10) is mounted on a gear part, preferably on the worm (20) itself. In case of malfunctioning, said locking device operates in addition to the deactivation of the electric motor (30) and reliably prevents it from executing another motion of revolution due to the fact that a locking pin (11) engages in a groove (21) which has the shape of an elongated hole. The shape of the groove has the advantage that a very precise positioning of the locking pin (11) is not required. Assembly tolerances are thus provided for. The development of noise is also reduced since it is very unlikely that the locking pin (11) will hit one of the intermediate bars before engaging in one of the grooves (21) thereby generating an unpleasant clacking noise. Additionally, a diagnostic circuit (40) could also be provided in order to check the functioning of the locking device (10) before starting up the vehicle. . |
