Brushless motor

1. A brushless motor comprising:

a shaft extending in a vertical direction along a rotation center axis, and arranged to rotate about the rotation center axis;

a bearing member arranged to rotatably support the shaft;

a rotor hub in a shape of a cup with a downward opening, and arranged to join together with the shaft;

a rotor magnet arranged radially inside the rotor hub;

a stator arranged radially inward of the rotor magnet and opposite the rotor magnet with a gap defined therebetween; and

a housing including a cylindrical portion, wherein said stator is position radially outside of said cylindrical portion; wherein

the stator includes an annular core back portion, a plurality of teeth extending radially outward from an outer circumference of the core back portion, and coils defined by a conductor wire wound around a separate one of the teeth;

the cylindrical portion includes a contact portion and a coming-off preventing portion arranged above the contact portion on an outer circumference of the cylindrical portion;

the core back portion includes a small-diameter opening defining portion and a large-diameter opening defining portion arranged above the small-diameter opening defining portion;

the cylindrical portion is arranged radially inward of the core back portion;

the stator is supported by the cylindrical portion with a lower surface of the core back portion arranged in contact with the contact portion and an upper surface of the small-diameter opening defining portion arranged in contact with the coming-off preventing portion;

the bearing member is arranged radially inside the large-diameter opening defining portion; and

the bearing member is arranged above the coming-off preventing portion.

2. The brushless motor according to claim 1 , further comprising a positioning portion arranged between the large-diameter opening defining portion and the small-diameter opening defining portion to position the bearing member, wherein

the bearing member is a ball bearing; and

an upper end surface of the positioning portion is arranged in contact with a lower surface of the bearing member.

3. The brushless motor according to claim 2 , wherein the positioning portion is defined by a portion of the stator.

4. The brushless motor according to claim 2 , wherein

an inner edge of the positioning portion includes a first section and a second section, the second section being more distant from the rotation center axis than the first section; and

the coming-off preventing portion includes a portion arranged radially outward of the first section.

5. The brushless motor according to claim 2 , wherein

the rotor hub includes a bottom portion and a joining portion extending axially downward from a radially inner edge of the bottom portion, the radially inner edge being arranged at a central portion of the bottom portion;

an inner circumferential surface of the joining portion is joined to the shaft; and

a lower surface of the joining portion is arranged in contact with an upper surface of the bearing member.

6. The brushless motor according to claim 5 , further comprising a lower bearing member, wherein

the housing further includes an accommodating portion arranged below the cylindrical portion to accommodate a lower bearing member; and

the accommodating portion includes a preload spring arranged above the lower bearing member.