A core includes a winding part, and a wall part including a first wall part, a second wall part spaced apart from the first wall part and disposed opposite to the first wall part, a third wall part in contact the first wall part, and a fourth wall part disposed opposite to the third wall part. The wall part surrounds the winding part.
1. A core comprising:
a winding part where a winding is wound; and
a wall part including a first wall part, a second wall part spaced apart from the first wall part and disposed opposite to the first wall part in a first direction, a third wall part in contact with the first wall part, and a fourth wall part spaced apart from the third wall part and disposed opposite to the third wall part in a second direction different from the first direction, the wall part surrounding the winding part,
wherein:
the winding part is spaced apart from the first wall part, the third wall part and the fourth wall part, and is included in the second wall part,
the first wall part, the second wall part, the third wall part, and the fourth wall part are separate from each other,
the winding part extends in the first direction between a contact point between the second wall part and the third wall part, and a contact point between the second wall part and the fourth wall part,
a distance between an external cooling part and the first wall part is greater than a distance between the external cooling part and the second wall part,
a space between the winding part and the first wall part is closer to the first wall part than to the second wall part in the first direction; and
the winding part is spaced apart from the first wall part, the third wall part and the fourth wall part, and is unitary with the second wall part.
2. The core according to claim 1 , wherein the first wall part, the second wall part, the third wall part, and the fourth wall part are configured to be movable with thermal expansion of the wall part.
3. The core according to claim 1 , wherein
the third wall part is configured to be movable with respect to the first wall part and the second wall part; and
the fourth wall part is configured to be movable with respect to the first wall part and the second wall part.
4. The core according to claim 1 , wherein
the second wall part is configured to be movable with respect to the third wall part and the fourth wall part.
5. The core according to claim 2 , wherein
the third wall part is configured to be movable with respect to the first wall part and the second wall part; and
the fourth wall part is configured to be movable with respect to the first wall part and the second wall part.
6. The core according to claim 1 , wherein
the second wall part contacts the external cooling part.
7. The core according to claim 4 , wherein
the second wall part contacts the external cooling part.