GB707701A - Method of and devices for producing and maintaining pendular motion by means of alternating currents or voltages - Google Patents

Abstract

707,701. Clocks, moving signs. CONSERVATOIRE NATIONAL DES ARTS ET METIERS, and LEFRAND, E. March 12, 1952 [March 22, 1951], No. 6440/52: Classes 31(1) and 139 [Also in Group XXXV] A conducting object is caused to move in a regular or irregular, circular or elliptical, pendular path for chronometric or display purposes by means of a ring of split-phase energized electrostatic or electromagnetic poles. In its simplest form, Fig. 1, a metal ball 13 is suspended over a ring of electromagnetic poles 25 fed with split-phase A.C. The ball executes its motion at its natural frequency and is propelled by induction motor effect by the rotating field produced by the poles. Starting may be achieved by means of an initial movement, by producing asymmetry in the pole-strengths, by putting a magnetic member on the mass 13, or by maintaining the pendulum at a radius by means of a rotary arm as shown in Fig. 4. In this form the electromagnets are radially arranged and the metal mass 43 has limited radial movement in a slot 64 in the freely rotatable spacing arm 62. The mass 43 is supported by a rod 44 and link 47 to drive a clock mechanism 68. In a modification (not shown), the electromagnets 53 are replaced by a three-phase induction motor stator having a fixed squirrel cage whose bars emerge beyond the stator core, the induced current in this cage producing the rotating field. Alternatively a commutated D.C. winding may be used to produce the rotating field. In a further form, Fig. 7, a suspended mass 93 is fitted with extensions 100 making it selfstarting on an elliptical path 106 when poles 102 are energized with split-phase current. The motion of the arm is used to control a clock escapement mechanism 107, 108. The arrangement of Fig. 1 may be adapted for displaying an object by replacing the metal ball 13 by a platform carrying a short-circuited ring, the supporting arm and supports for the base 11 being resilient to produce an irregular motion. In another device the electromagnets are concealed in a stationary bottle around which a suspended bottle gyrates. The pendular motion may be produced by a ball rolling in a closed track on an inclined plane and the restoring force may be other than gravity.