Patent ID: 7646194

Claim:
A variable reluctance resolver, comprising: a resolver stator portion having a substantially annular shape centered about a central axis and including an excitation coil and an output coil; and a rotor portion having a rotor core arranged concentrically with respect to the central axis, rotatably supported with respect to the resolver stator portion, and arranged radially inward of the resolver stator portion via a gap g therebetween, wherein a size of the gap g is calculated by a following equation: g = 1 1 2 ⁢ ( 1 g min + 1 g max ) + 1 2 ⁢ ( 1 g min - 1 g max ) · cos ⁡ ( n ⁢ ⁢ θ ) + K ( 1 - cos ⁡ ( 2 ⁢ ⁢ n ⁢ ⁢ θ ) in which g max is a minimum value for the gap g, g min is a maximum value for the gap g, angle θ is defined between a point of reference and a predetermined point set at an outer circumferential end of the core, n is an axial double angle which is a positive integer, and K is a coefficient.