Electric motor

Inventors: Tatsuya Tonari (Osaka, JP); Hisato Sumitomo (Osaka, JP); Yuji Nakazawa (Osaka, JP); Taiichi Nose (Osaka, JP); Hirofumi Higashi (Osaka, JP)

Assignee: DAIKIN INDUSTRIES, LTD.

H02K1/276 F25B31/026 H02K1/32 H02K21/14

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Quick Facts

Patent No.: US 12683442
App. No.: 17/464,509
Granted: Jul 14, 2026
Kind: B2

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Abstract

An electric motor includes a stator, and a rotor having a plurality of magnetic poles. Each magnetic pole includes a rotor core having through holes arranged circumferentially side by side, and a permanent magnet inserted into each through hole. A length of a portion of the rotor core in a radial direction of the rotor is shorter than a length of the permanent magnet in the radial direction of the rotor. The length of the portion of the rotor core is measured between an inner surface of each of the through holes adjacent to an outer periphery of the rotor and an outer peripheral surface of the rotor. The permanent magnets generate a magnetic flux in a magnetic circuit showing a smaller magnetic resistance in a portion of the rotor radially outward of the permanent magnets than in a portion of the rotor radially inward of the permanent magnets.

Claims (55)

1 . An electric motor comprising:

a stator; and

a rotor having a plurality of magnetic poles, each of the magnetic poles of the rotor including

a rotor core having a plurality of through holes arranged side by side in a circumferential direction of the rotor, and

a permanent magnet inserted into each of the through holes to form a gap between the permanent magnet and the through hole in which the permanent magnet is inserted,

lengths of portions of the rotor core in a radial direction of the rotor being shorter than lengths of the permanent magnets in the radial direction of the rotor, the lengths of the portions of the rotor core being measured between an inner surface of each of the through holes adjacent to an outer periphery of the rotor and an outer peripheral surface of the rotor, and

the permanent magnets generating a magnetic flux in a magnetic circuit, and the magnetic circuit showing a smaller magnetic resistance in a portion of the rotor radially outward of the permanent magnets than in a portion of the rotor radially inward of the permanent magnets,

the plurality of magnetic poles including magnetic poles having polarities different from each other and being adjacent to each other,

a first distance being measured between an outer surface of a radially inward portion of the permanent magnet and an inner surface of a radially inward portion of the through hole near a border of the magnetic poles adjacent to each other,

a second distance being measured between an outer surface of a radially inward portion of the permanent magnet and an inner surface of a radially inward portion of the through hole in a center portion of the magnetic poles adjacent to each other, and the first distance being larger than the second distance,

the magnets being positioned in the through holes such that the maximum dimension of circumferential portions of the gaps that circumferentially face each other near the border of the magnetic poles having polarities different from each other and adjacent to each other are smaller than the first distance, and

a rib being provided between the permanent magnets adjacent to each other in the circumferential direction, the rib extending from the radially inner end of the permanent magnets to the radially outer end of the permanent magnets, and the width of the rib being generally constant.

2 . The electric motor of claim 1 , wherein

when viewed along an axial direction of the rotor, the permanent magnets and the through holes are shaped to restrict a position of each of the permanent magnets in the radial direction of the rotor so that an average radial dimension of each gap is smaller

in an outer portion of the gap adjacent to the outer periphery of the rotor than

in an inner portion of the gap adjacent to the inner periphery of the rotor.

3 . The electric motor of claim 2 , wherein

the inner surface of each of the through holes adjacent to the inner periphery of the rotor includes

an adjacent portion formed along the outer surface of a corresponding one of the permanent magnets, and

a distant portion that is more distant from the outer surface of the corresponding one of the permanent magnets than the adjacent portion.

4 . The electric motor of claim 3 , wherein

the distant portion is provided only at an end portion of each of the through holes in a circumferential direction of the rotor.

5 . The electric motor of claim 4 , wherein

each of the magnetic poles has at least two through holes, and

the through hole closest to an adjacent magnetic pole of different polarity has the distant portion provided only at an end portion of the through hole in the circumferential direction of the rotor, the end portion being adjacent to the magnetic pole of different polarity.

6 . The electric motor of claim 5 , wherein

each of the magnetic poles has at least three through holes, and

the through hole closest to the adjacent magnetic pole of different polarity has the distant portion.

7 . The electric motor of claim 5 , wherein