Interior permanent magnet motor, compressor and refrigeration and air conditioning apparatus

1. An interior permanent magnet motor, comprising:

a stator; and

a rotor rotatably arranged so as to be opposed to the stator,

wherein the rotor comprises a rotor core having a plurality of magnet insertion holes formed therein, into which corresponding permanent magnets are respectively inserted,

wherein an air gap is secured between a rotor outer peripheral surface of the rotor and a stator inner peripheral surface of the stator,

wherein the stator comprises a plurality of tooth portions,

wherein a tooth tip portion having both side portions expanding in a circumferential direction is formed on a distal end portion of each of the tooth portions,

wherein the rotor outer peripheral surface comprises, when viewed in a cross-section orthogonal to a rotation center line:

a plurality of first arcs; and

a plurality of second arcs,

wherein each of the first arcs is positioned in a corresponding magnetic pole center portion on the rotor outer peripheral surface,

wherein each of the second arcs is positioned in a corresponding inter-pole portion on the rotor outer peripheral surface,

wherein the first arc bulges toward a radially outer side to a higher degree than the second arc so that the air gap is varied in a manner of being increased as approaching from each of the magnetic pole center portions to the adjacent inter-pole portions,

wherein, when viewed in the cross-section orthogonal to the rotation center line, a hole defining portion of each of the magnet insertion holes of the rotor core on the radially outer side has a curvature of a third arc, and a hole defining portion of the each of the magnet insertion holes of the rotor core on a radially inner side has a curvature of a fourth arc, and

wherein an opening angle of the tooth tip portion, an opening angle of the first arc, and an opening angle of the third arc coincide with each other.

2. An interior permanent magnet motor according to claim 1 ,

wherein a center of a radius of the first arc is set to a position displaced toward a magnetic pole side from the rotation center line, and

wherein a center of a radius of the third arc is set in the tooth tip portion.

3. An interior permanent magnet motor according to claim 1 , wherein an opening angle between the tooth tip portions of a pair of the tooth portions, which are located on both sides of the each of the tooth portions, is smaller than an opening angle of the fourth arc.

4. An interior permanent magnet motor according to any one of claim 1 ,

wherein an inter-pole thin portion having a uniform thickness is secured between a magnet-side surface opposing portion of the magnet insertion hole, which receives a side surface portion of the permanent magnet, and the second arc, and

wherein, assuming that a narrowest interval of the air gap between the magnetic pole center portion on the first arc on the rotor outer peripheral surface and the stator inner peripheral surface of the tooth tip portion is defined as Ga, a dimension obtained by further adding the thickness of the inter-pole thin portion to a widest interval of the air gap between the second arc on the rotor outer peripheral surface and the stator inner peripheral surface of the tooth tip portion is defined as Gb, and an interval of the adjacent tooth tip portions is defined as Gc, a magnitude relationship of 2×(Ga)<(Gc)<2×(Gb) is satisfied.

5. An interior permanent magnet motor according to claim 1 ,

wherein a pair of slits are formed in a region between each of the third arcs and the corresponding first arc,

wherein each of the slits extends along an extending direction of the radius of the third arc, and

wherein the pair of slits are formed to be line symmetrical with respect to an inter-pole center line as a center line.

6. A compressor, comprising, in an airtight container:

a motor; and

a compression element,

wherein the motor comprises the interior permanent magnet motor of claim 1 .

7. A refrigeration and air conditioning apparatus, comprising the compressor of claim 6 as a component of a refrigeration cycle.