Positioning mechanism of resolver and electrically-driven power steering apparatus

1. A positioning mechanism of a resolver, which is disposed at a housing member for receiving a brushless motor which has a rotor and a stator having a plurality of coils to rotate the rotor by alternately changing electrical conduction to the coils, a resolver stator received in the housing member and a resolver rotor which is coupled and fixed at a constant circumferential position with respect to the rotor to rotate together with the rotor and which detects a rotational position of the rotor with respect to the stator, a holding portion holding the resolver stator being formed in the stator, and a positioning member for positioning the resolver stator with respect to the stator being coupled and fixed to the stator to be positioned at a constant circumferential position with respect to the stator, and wherein the resolver stator is held by the holding portion so as to be positioned at the constant circumferential position with respect to the stator,

the positioning member being constructed with bobbins which are positioned at constant circumferential positions with respect to the stator and a bus ring holder which is positioned at a constant circumferential position with respect to the bobbins, and wherein the holding portion is formed in the bus ring holder.

2. The positioning mechanism of a resolver according to claim 1 , the holding portion is a groove portion formed in the bus ring holder, a supporting member which is engaged with the groove portion is coupled and fixed to the resolver stator, and wherein the resolver stator is positioned at the constant circumferential position with respect to the stator by engaging the supporting member with the groove portion.

3. The positioning mechanism of a resolver according to claim 2 , a supporting frame having two arc-shaped frame portions as the supporting member is disposed to an outer circumference of the resolver stator, each of the arc-shaped frame portions is constructed with two straight portions which extend in a radial direction and an arc-shaped portion which connects at least one-side end of the straight portions, the groove portion being formed in a distal end of each of four arm portions which extend in an axial direction of the bus ring holder, and wherein each straight portion of the resolver stator is engaged with the groove portion.

4. An electrically-driven power steering apparatus having the positioning mechanism according to claim 3 .

5. An electrically-driven power steering apparatus having the positioning mechanism according to claim 2 .

6. An electrically-driven power steering apparatus having the positioning mechanism according to claim 1 .