1. Field of the Invention
The invention relates generally to a recirculating ball screw and nut drive with a spindle and with a spindle nut guided on the spindle, as well as with balls guided between the spindle and the spindle nut, in a working passage between their thread grooves, where the balls are diverted in ball deflection pieces on both ends of the spindle nut out of the working passage into a return passage accommodated in the spindle nut, and vice versa.
2. Discussion of Background Information
A recirculating ball screw and nut drive is generally disclosed in GB-PS-957330. This recirculating ball screw and nut drive includes a spindle and a spindle nut guided on the spindle with balls guided between their thread grooves in a working passage. Both the spindle nut and the spindle have a single-start thread. In order to change the ratio of the feed of the spindle nut to the rotation of the spindle, the pitch of the threads should be changed. However, with a large pitch of the threads, the load-carrying capacity of the ball screw and nut drive decreases with a constant length of the spindle nut, because fewer balls can engage in a load-carrying manner with the opposite grooves. As a remedy, a multiple-start thread is used for the spindle and for the spindle nut. However, the ball deflection piece provided for a single-start thread can no longer be used.
Another recirculating ball screw and nut drive with two ball deflection pieces attached to the two ends of the spindle nut is generally disclosed in DE-T2-60301517, where the ball deflection pieces are suitable for a spindle and spindle nut having a multiple-start thread. For each working passage lying between the threads and for each associated return passage, the ball deflection piece made of one piece features one ball circulation passage connecting these passages. However, this ball deflection piece is complicated and requires expensive manufacturing and mounting.