Stator design for a stepping motor

Claim 1

A stepping motor comprising a stator having a plurality of salient poles, each pole terminating in an arcuate inner surface with the arcuate surfaces defining a cylindrical opening, and a cylindrical rotor rotatably positioned in said opening, the rotor including a permanent magnet and first and second cylindrical members forming the respective poles of said magnet, the first and second members having teeth around the periphery thereof with the teeth in the two members being axially aligned, and the arcuate surfaces of each of the salient poles of the stator having teeth projecting toward the teeth in the rotor, said teeth in each pole extending parallel to the rotational axis of the rotor the full length of the stator, the portion of each tooth extending half the length of the stator being offset from the portion extending the remaining half of the length, the offset of the teeth between the two halves of the stator being equal to one half the pitch of the teeth, the stator including a plurality of thin laminations joined in a stack, all of the laminations being identical in shape, each lamination having the teeth of each salient pole offset relative to the centerline of the pole by one-fourth the pitch of the teeth.

Claim 5

The method of constructing a stator core for a stepping motor comprising the steps of forming a group of identically shaped laminations with each lamination having an outer ring portion and a plurality of radially inwardly projecting pole portions, with pole portions having a group of equally spaced teeth offset circumferentially relative to the pole portions, stacking the laminations with the pole portions aligned but with laminations in one-half the stack reversed from the laminations in the other half of the stack so that the teeth in one-half of the stack are displaced circumferentially by twice the amount of said offset relative to the teeth of the other half of the stack, and joining the laminations together to provide a rigid stator core structure.

Claim 6

The method of constructing a stator core for a stepping motor comprising the steps of forming a group of identically shaped laminations with each lamination having an outer ring portion and a plurality of radially inwardly projecting pole portions, with pole portions having a group of equally spaced teeth offset circumferentially relative to the pole portions, stacking the laminations with the pole portions aligned but with laminations in one-half the stack reversed from the laminations in the other half of the stack so that the teeth in one-half of the stack are displaced circumferentially by twice the amount of said offset relative to the teeth of the other half of the stack, and joining the laminations together to provide a rigid stator core structure.