US 4,276,511 A · Magnetic systems for long scale electrical meter with multiple side coil sensing

Abstract

A magnetic system for a long scale electrical meter enables four sided sensing of a coil which is completely offset from the axis of rotation has a cylindrical core pole piece magnetically coupled to first similar poles of two magnets. The core is surrounded by an inner annular air gap defined by a coaxial inner annular pole piece which is magnetically coupled to the second poles of the magnets. Radially outward is an outer annular air gap defined by a coaxial outer annular pole piece which is magnetically coupled to the first magnetic pole. Magnetic fields in the inner and outer air gaps are radial. The outer annular pole piece is closed at opposite ends by a pair of magnetically permeable discs which also are pole pieces for the first magnetic pole. Each disc is spaced apart a distance D from the nearest flat face of the inner annular pole piece to provide axial magnetic fields. Accordingly, all four sides of the coil are active. A system for three sided sensing is similar but has one magnet and no core piece. Each of two pole pieces has a straight leg section and an annular section. The magnet is positioned between the adjacent but spaced apart leg sections, and the annular sections are concentric to form an annular air gap in which the coil moves. The outer annulus is wider than the inner one, and its flat side faces on both sides are closed by magnetically permeable discs which are equispaced from the side (radially oriented) faces of the inner annular pole piece to provide axial fields.

Claims7

Dependent claims

A magnetic system for a rotor having a coil, said coil including at least two radially oriented sides and at least two axially oriented sides, for four side coil sensing, said magnetic system comprising:

at least one magnet having poles;
a core pole piece;
an outer annular pole piece having two axial ends, said outer annular pole piece surrounding said core pole piece and spaced therefrom, both of said pole pieces magnetically coupled to the same pole of said at least one magnet;
an inner annular pole piece, magnetically coupled to the other pole of said at least one magnet, said inner annular pole piece having an inside radius and disposed substantially between said core pole piece and said outer annular pole piece and defining an inner annular air gap between said core pole piece and said inner annular pole piece and defining an outer annular air gap between said inner annular pole piece and said outer annular pole piece;
and
two radial pole pieces, each magnetically coupled to said same pole and positioned proximate each axial end of said outer annular pole piece and extending radially inwardly at least as far as the inside radius of said inner annular pole piece and spaced therefrom to form radial air gaps, whereby the axially oriented sides of said coil move in said inner and outer annular air gaps through parallel but opposing radial magnetic fields, and the radially oriented sides of said coil move in said radial air gaps through axial but opposing magnetic fields.

3 more elements

Dependencies are inferred from the claim text.

Magnetic systems for long scale electrical meter with multiple side coil sensing

Life of this patent

Magnetic systems for long scale electrical meter with multiple side coil sensing

Life of this patent

Abstract

Claims7