Vehicle power antenna control with drive stress limiting

摘要

A power antenna control for a motor vehicle comprises a Hall effect device responsive to motor armature rotation to generate pulses for equal predetermined increments of antenna travel. These pulses are applied to both position and stall counters. In extension, the antenna drive is stopped when the position counter reaches a number corresponding to a predetermined extended position, which may be full extension or some lesser extension. In retraction, the stall counter is used with a clock to indicate stall which, when detected, causes the antenna drive to be stopped. Automatic current limiting for drive torque limitation during stall is activated only when the position counter indicates a limited position range near full retraction. Further during retraction, if the antenna is stopped within a small position range of full rectraction, it is reset to a count indicating full retraction. The system eliminates the need for hard stall sensing reaction switches and thus reduces antenna drive cable fatigue.