Patent ID: 8373324
Filing Date: 2013-02-12
Classification: H02K

Abstract:
1. A field element core, comprising: field magnet through holes circularly disposed in a peripheral direction around a predetermined axis and being adjacent to each other in said peripheral direction to form sets, each of the field magnet through holes having a pair of ends in said peripheral direction; and a coupling part provided between two of said field magnet through holes forming one of said sets, said coupling part having lateral surfaces, said ends that belong to said two of said field magnet through holes respectively and are adjacent to each other in said peripheral direction, wherein: at least one of said lateral surfaces includes at least one of curved portions extending along a circle with a center positioned on a side opposite to said coupling part with respect to said at least one of said lateral surfaces, viewed from a first direction along said axis; and a first ratio x and a second ratio y satisfy: wherein said curved portion, x represents a ratio of a radius of said circle with respect to a length in a third direction perpendicular to a second direction in which one of said field magnet through holes including said at least one of said lateral surfaces extends from said coupling part, and y represents a ratio of a distance between a surface of said one of said field magnet through holes positioned on a side towards said axis in a radial direction and said center with respect to said length of said coupling part in said third direction, a center of said radial direction being said axis.