Electric starter for IC engine - has contactor with cover edge crimped over base to reduce parasitic magnetic losses

摘要

The starter comprises an electric motor (1) and a contactor (3) with a cover (6) enclosing the coil and an attached base (7) forming the fixed core. The free edge (6a) of the cover (6) is crimped directly around a lip defined by a peripheral groove around the base (7). Pref. this groove has a semi-circular cross-section and the free edge (6a) of the cover (6) has a reduced wall thickness, its inner and outer dia. respectively greater and less than the inner and outer dia. of the cover (6), to define a shoulder (6c) on both the inside and the outside of the cover (6). The crimped edge (6a) of the cover (6) is surrounded by a sleeve (8) of a metal with good electrical conduction, e.g. Cu, Al or one of their alloys, acting as a short-circuit ring during the crimping process. The cover and base of the contactor are fitted together to reduce magnetic losses between them.