Stator unit and motor
A stator unit including a coil in which a distance between an m−1-th turn and an m-th turn is wider than each distance in a first turn to the m−1-th turn. The m+1-th turn is disposed between the m−1-th turn and the m-th turn. Further, in a cross-section perpendicular to a central axis and passing a tooth, an angle between a line segment connecting respective centers of the m+1-th turn and the m−1-th turn and a line segment connecting respective centers of the m+1-th turn and the m-th turn is about 120° or more. With this structure, bulging in a circumferential direction of the coil adjacent to an inner peripheral portion of the tooth can be suppressed and a clearance can be secured between adjacent coils such that the number of turns of the coil can be increased.
1. A stator unit comprising:
a plurality of teeth extending in a radial direction with respect to a central axis;
an insulator that covers each of the plurality of teeth; and
a coil that is defined by a conducting wire wound around the insulator; wherein
when m is set to be an integer equal to 2 or more and n is set to be an integer larger than m+1, the coil includes:
a first layer defined by a first turn to an m-th turn; and
a second layer defined by an m+1-th turn to an n-th turn;
a first turn to the m-th turn are sequentially wound around the insulator toward inside in the radial direction from outside in the radial direction;
the m+1-th turn to the n-th turn are sequentially wound toward the outside in the radial direction from the inside in the radial direction;
a distance between an m−1-th turn and the m-th turn is wider than each distance in the first turn to the m−1-th turn;
the m+1-th turn is disposed between the m−1-th turn and the m-th turn;
in a cross-section perpendicular or substantially perpendicular to the central axis and passing through the tooth, an angle between a line segment connecting respective centers of the m+1-th turn and the m−1-th turn and a line segment connecting respective centers of the m+1-th turn and the m-th turn is more than or equal to about 120° and less than about 180°; and
a space is provided between the m+1-th turn and the insulator.
2. The stator unit according to claim 1 , wherein the m+1 turn is in contact with the insulator.
3. The stator unit according to claim 2 , wherein the insulator includes a wall portion protruding in a direction away from the tooth between the m−1-th turn and the m-th turn; and
the m+1-th turn is in contact with the wall portion.
4. The stator unit according to claim 3 , wherein an m+1-th groove extending along the m+1-th turn of the coil is provided in the surface of the wall portion.
5. The stator unit according to claim 4 , wherein a length of the m+1-th groove in a direction along the conducting wire is shorter than lengths from the first groove to the m-th groove in a direction along the conducting wire.
6. The stator unit according to claim 4 , wherein the m+1-th groove is defined by a curved surface having curvature equal or approximately equal to that of an outer circumferential surface of the conducting wire.
7. The stator unit according to claim 1 , wherein the number of teeth is 6 or more.
8. The stator unit according to claim 1 , wherein the insulator includes a boundary convex portion protruding toward a direction away from the tooth, at a boundary portion between the m−1-th turn and the m+1-th turn; and
an apex portion of the boundary convex portion is farther away from the tooth than a surface of the insulator in a boundary portion between the m-th turn and the m+1-th turn.
9. The stator unit according to claim 1 , wherein the insulator includes a first groove to an m-th groove which respectively extend along the first turn to the m-th turn of the coil.
10. The stator unit according to claim 9 , wherein each of the first groove to the m-th groove is defined by a curved surface having curvature equal or approximately equal to that of an outer circumferential surface of the conducting wire.
11. The stator unit according to claim 9 , wherein the first groove to the m-th groove are arranged to extend over a side surface of the insulator and at least a portion of an upper surface or a lower surface of the insulator.
12. The stator unit according to claim 9 , wherein the m-th groove is shallower than the first groove to the m−1-th groove.
13. The stator unit according to claim 1 , wherein a distance between the m−2-th turn and the m−1-th turn is wider than each distance in the first turn to the m−2-th turn; and
a portion of the conducting wire defining the second layer is arranged between the m−2-th turn and the m−1-th turn.
14. The stator unit according to claim 1 , wherein each of the m+1-th turn to the n-th turn are in contact with the insulator.
15. A motor comprising:
the stator unit according to claim 1 ; and
a magnet including a magnetic pole surface which faces end surfaces of a plurality of teeth; wherein
the stator unit and the magnet are supported so as to be able to relatively rotate about the central axis.