GB378343A - Improvements in electrical starting motors for internal combustion engines - Google Patents

Abstract

378,343. Motors. BOSCH AKT.-GES., R., 4, Militõrstrasse, Stuttgart, Germany. Feb. 24, 1932, No. 5464. Convention date, June 13, 1931. [Class 35.] Exciting ; motors.controlling ; rotary machines. -An electric motor for starting internal-combustion engines having a longitudinally displaceable armature is provided with a main current field winding g and an auxiliary field winding b producing together a multipolar field, and a shunt holding winding n arranged to produce a number of poles which is a fraction of the number of poles produced by the main and auxiliary windings. The contacts c, d of the starting switch first close the circuit of the motor through the auxiliary series winding b wound on the poles m whereupon the armature is attracted against the action of a spring and a pinion on the shaft engages the toothed rim of the engine flywheel which is thereby set in slow rotation. Contacts f, c then connect the main series winding g wound on the poles k in parallel with the auxiliary winding b and the armature accelerates in a four-pole field. The holding winding n which prevents a premature release of the armature is wound on the poles m to give a two-pole field so that it has no effect on the motor speed. Since the field of the shunt winding weakens the field of the auxiliary winding on one of the poles, the starting switch may be arranged to close the circuit of the winding n after the closure of the auxiliary winding circuit by connecting the end x to the contact / so that the attraction of the armature by the auxiliary winding field is not delayed.