Magnet for motor and washing machine including the same

1 . A washing machine comprising:

a motor comprising:

a stator;

a rotor including a rotor core disposed radially outside the stator; and

a plurality of magnets that are disposed on an inner surface of the rotor core and that face the stator,

wherein each of the plurality of magnets comprises:

one or more polar regions each having an arc shape and arranged in a circumferential direction,

wherein a magnetic focus center of each of the one or more polar regions is different from a center of an inner diameter of the one or more polar regions,

wherein a value X that is obtained by dividing (i) d m , a distance from a first straight line that connects a first end and a second end of a first magnetic center line of the one or more polar regions to a center of the first magnetic center line, by (ii) d b , a distance from a second straight line that connects a first end and a second end of a second magnetic center line of the one or more polar regions to a center of the second magnetic center line, satisfies at least one of following values based on a number of the one or more polar regions:

X<7.5 based on the number of the one or more polar regions being 1;

X<6 based on the number being 2;

X<4.5 based on the number being 3; or

X<3.5 based on the number being 4, and

wherein d b is determined based on the one or more polar regions having a magnetic focus center that corresponds to the center of the inner diameter.

2 . The washing machine of claim 1 , wherein d b satisfies the following equation:

d

b

=

r

i

+

r

o

2

-

(

r

i

+

r

o

2

)

2

-

(

r

o

-

r

i

2

⁢

p

)

2

,

wherein r i corresponds to an inner radius of the one or more polar regions,

wherein r o corresponds to an outer radius of the one or more polar regions, and

wherein p corresponds to the number of the one or more polar regions.

3 . The washing machine of claim 1 , wherein the value X satisfies at least one of following values based on the number of the one or more polar regions:

6<X<7.5 based on the number being 1;

4.5<X<6 based on the number being 2;

3.5<X<4.5 based on the number being 3; or

2.5<X<3.5 based on the number being 4.

4 . The washing machine of claim 1 , wherein the one or more polar regions are provided in a plurality, and

wherein distances from each magnetic focus center of each of the plurality of polar regions to each of the plurality of polar regions are equal.

5 . The washing machine of claim 1 , wherein the one or more polar regions are provided in a plurality, and

wherein circumferential distances between adjacent magnetic focus centers of the plurality of polar regions are equal.

6 . The washing machine of claim 1 , wherein the stator comprises a plurality of stator teeth, and

wherein the plurality of magnets that are disposed on an inner surface of the rotor core face the plurality of stator teeth.

7 . A magnet comprising:

one or more polar regions each having an arc shape and arranged in a circumferential direction,

wherein a magnetic focus center of each of the one or more polar regions is different from a center of an inner diameter of the one or more polar regions,

wherein a value X that is obtained by dividing (i) d m , a distance from a first straight line that connects a first end and a second end of a first magnetic center line of the one or more polar regions to a center of the first magnetic center line, by (ii) d b , a distance from a second straight line that connects a first end and a second end of a second magnetic center line of the one or more polar regions to a center of the second magnetic center line, satisfies at least one of following values based on a number of the one or more polar regions:

X<7.5 based on the number of the one or more polar regions being 1,

X<6 based on the number being 2,

X<4.5 based on the number being 3, or

X<3.5 based on the number being 4, and

wherein d b is determined based on the one or more polar regions having a magnetic focus center that corresponds to the center of the inner diameter.

8 . The magnet of claim 7 , wherein d b satisfies the following equation:

d

b

=

r

i

+

r

o

2

-

(

r

i

+

r

o

2

)

2

-

(

r

o

-

r

i

2

⁢

p

)

2

,

wherein r i corresponds to an inner radius of the one or more polar regions,

wherein r o corresponds to an outer radius of the one or more polar regions, and

wherein p corresponds to the number of the one or more polar regions.

9 . The magnet of claim 7 , wherein the value X satisfies at least one of following values based on the number of the one or more polar regions:

6<X based on the number being 1;

4.5<X based on the number being 2;

3.5<X based on the number being 3; or

2.5<X based on the number being 4.

10 . The magnet of claim 7 , wherein the one or more polar regions are provided in a plurality, and

wherein distances from each magnetic focus center of each of the plurality of polar regions to each of the plurality of polar regions are equal.

11 . The magnet of claim 7 , wherein the one or more polar regions are provided in a plurality, and

wherein circumferential distances between adjacent magnetic focus centers of the plurality of polar regions are equal.

12 . The magnet of claim 7 , wherein the one or more polar regions are provided in a plurality, and

wherein neighboring polar regions of the plurality of polar regions have different polarities.

13 . A magnet comprising:

one or more polar regions each having an arc shape and arranged in a circumferential direction,

wherein a magnetic focus center of each of the one or more polar regions is different from a center of an inner diameter of the one or more polar regions,

wherein a value X that is obtained by dividing (i) d m , a distance from a first straight line that connects a first end and a second end of a first magnetic center line of the one or more polar regions to a center of the first magnetic center line, by (ii) d b , a distance from a second straight line that connects a first end and a second end of a second magnetic center line of the one or more polar regions to a center of the second magnetic center line, satisfies at least one of following values based on a number of the one or more polar regions:

6<X based on the number of the one or more polar regions being 1,

4.5<X based on the number being 2,

3.5<X based on the number being 3, or

2.5<X based on the number being 4, and

wherein d b is determined based on the one or more polar regions having a magnetic focus center that corresponds to the center of the inner diameter.

14 . The magnet of claim 13 , wherein d b satisfies the following equation:

d

b

=

r

i

+

r

o

2

-

(

r

i

+

r

o

2

)

2

-

(

r

o

-

r

i

2

⁢

p

)

2

,

wherein r i corresponds to an inner radius of the one or more polar regions,

wherein r o corresponds to an outer radius of the one or more polar regions, and

wherein p corresponds to the number of the one or more polar regions.

15 . The magnet of claim 13 , wherein the one or more polar regions are provided in a plurality, and

wherein distances from each magnetic focus center of each of the plurality of polar regions to each of the plurality of polar regions are equal.

16 . The magnet of claim 13 , wherein the one or more polar regions are provided in a plurality, and

wherein circumferential distances between adjacent magnetic focus centers of the plurality of polar regions are equal.

17 . The magnet of claim 13 , wherein the one or more polar regions are provided in a plurality, and

wherein neighboring polar regions of the plurality of polar regions have different polarities.

18 . A motor comprising:

a stator;

a rotor including a rotor core disposed radially outside the stator; and

a plurality of magnets that are disposed on an inner surface of the rotor core and that face the stator,

wherein each of the plurality of magnets comprises:

one or more polar regions each having an arc shape and arranged in a circumferential direction,

wherein a magnetic focus center of each of the one or more polar regions is different from a center of an inner diameter of the one or more polar regions,

wherein a value X that is obtained by dividing (i) d m , a distance from a first straight line that connects a first end and a second end of a first magnetic center line of the one or more polar regions to a center of the first magnetic center line, by (ii) d b , a distance from a second straight line that connects a first end and a second end of a second magnetic center line of the one or more polar regions to a center of the second magnetic center line, satisfies at least one of following values based on a number of the one or more polar regions:

X<7.5 based on the number of the one or more polar regions being 1;

X<6 based on the number being 2;

X<4.5 based on the number being 3; or

X<3.5 based on the number being 4, and

wherein d b is determined based on the one or more polar regions having a magnetic focus center that corresponds to the center of the inner diameter.

19 . The motor of claim 18 , wherein:

based on a number of the one or more polar regions being 1, a number of the plurality of magnets is 48;

based on the number of the one or more polar regions being 2, the number of the plurality of magnets is 24;

based on the number of the one or more polar regions being 3, the number of the plurality of magnets is 16; and

based on the number of the one or more polar regions being 4, the number of the plurality of magnets is 12.