GB1198526A - Motor having a Plurality of Speeds which can be Switched Selectively. - Google Patents

Abstract

1,198,526. Electric motors. LICENTIA PATENT VERWALTUNGS G.m.b.H. 18 Aug., 1967 [23 Aug., 1966; 18 Oct., 1966; 15 April, 1967], No. 38095/67. Heading H2A. An electric motor providing two widely different speeds for washing machines has a commutated high-speed armature 13 inside the stator 12 and a low-speed multi-polar induction rotor 14 outside it, both rotors being mounted on the same drive shaft. The induction motor stator is wound for 12 poles and may polechange to six poles e.g. by the Dahlander connection, for distributing the washing prior to spinning. The internal stator poles 15, 16 carry series windings 17, 18 and the induction winding (not shown) lies in external slots 21. Additional two-pole windings 19, 20 on the inner poles and 24 lying in deeper peripheral slots 23, cause some two-pole flux to pass out into the squirrelcage rotor 14. This has the effect of imposing a two-pole induction torque on it so that the spinning-speed may be restrained to 3000 a stable R.P.M. for low-speed spinning. These additional coils may be switched in or out to give the spinning speed required (Fig. 3, not shown). In order to avoid needless brush-wear during induction motoring, the brushes may be raised electromagnetically. In the arrangement shown in Fig. 5, the brush 31 is surmounted by a magnetic ferrule by means of which it is drawn up by coil 37. Alternatively the brush may be on a spring-loaded arm. The inner motor may have a permanent-magnet rotor and be commutated electronically (Fig. 7, not shown). The rotor may be between two stators (Fig. 8, not shown).