GB1135579A - Electrical generators - Google Patents

Abstract

1,135,579. Reciprocating generators. NATIONAL RESEARCH DEVELOPMENT CORP. 9 Dec., 1966 [20 Dec., 1965], No. 53782/65. Heading H2A. An electrical generator comprises a member of magnetic material arranged for reciprocating motion, an electrical winding arranged to be energized by direct current to produce magnetic flux, the reluctance of the path for which varies with the position of the member, and means for allowing an alternating output current due to an alternating voltage generated in the winding when the above-mentioned reluctance changes, to be taken, without a substantial direct current component, from the generator. As shown, a cylindrical member 1 reciprocates between the positions shown inside a hollow cylindrical casing 2 around which two coils 3, 4 are provided. When coils 3 and 4 are energized by direct current, the path for flux produced by coil 3 includes the member 1 when it is in the extreme position shown, and the path for flux produced by coil 4 includes the member 1 when it is in the opposite extreme position. Thus the magnitudes of the fluxes alternately vary between maximum and minimum values as member 1 reciprocates. This flux variation induces A.C. in windings 3 and 4, and currents without substantial D.C. components can be extracted from the windings by means such as a transformer coupling. The member 1 may be driven by a single cylinder I.C. engine, or the arrangement 1, 2 may itself constitute the I.C. engine. The invention may take the form of a single cylinder, double piston, arrangement (Fig. 2, not shown). While the direct current may be provided from an external source, part of the A.C. output may be rectified and fed back for D.C. excitation. In the latter case, initial induction may be provided by a small bar magnet extending axially of the piston.