GB280858A - An improved synchronous electric motor - Google Patents

Abstract

280,858. Schneider et Cie. Nov. 17, 1926, [Convention date]. Alternating - cur - rent motors; motors with unwound iron armatures; driving- arrangements; coils and conductors. - The rotor of a single-phase or polyphase synchronous motor having the property also of asynchronous run - ning consists in one part of perforated laminae, as used in asynchronous motors, and in another part of laminae which are both perforated and notched so that when assembled they form two pole-pieces in a squirrel-cage rotor. In the form shown the plates C, are of soft iron or magnetized steel, and are notched to form two polepieces C<1>, C<2>. A second set of plates B is of the kind used in the rotors of asynchronous motors. Both sets of plates are provided with slots b, c, in which there is cast a squirrel-cage winding D, preferably of aluminium which forms also the ends D', D<2> of the cage. The field magnet of the motor is formed like the stator of an asynchronous motor, the coils being connected in an arrangement having a neutral point. The squirrel cage may be made in the known manner by riveting copper rods upon two rings of the same metal, or by making an electrolytic deposit. The armature slots may run parallel to the shaft or may be curved so as to have a helical form. The length of the stator may be equal to the length of the rotor, or it may be reduced to the length of the pole-pieces and provision made for displacement of the rotor relatively to the stator, after starting, for bringing the stator opposite the pole-pieces. Motors of the kind described may be used for the actuation of Baudot type telegraphs, teletype machines, stroboscopic, and television apparatus. In the case of a number of wheels which are to be driven in constant angular relationship by motors having different synchronous speeds, a train of gearing, giving a multiplication of speed of 2p may be interposed between each motor and the corresponding wheel, 2p being the number of poles of the motor.