Motor unit

1. A motor unit comprising:

a motor including a shaft to rotate about a motor axis extending in a horizontal direction and a stator surrounding the shaft from radially outside;

a reduction gear connected to the shaft; and

a housing including a housing space to house the motor and the reduction gear; wherein the housing space includes:

a motor chamber to house the motor; and

a gear chamber to house the reduction gear;

the housing includes a partition to divide the motor chamber and the gear chamber;

the shaft includes:

a first shaft portion, a connecting shaft portion, and a second shaft portion arranged coaxially with one another; and

a separating mechanism between the connecting shaft portion and the second shaft portion;

the first shaft portion includes a first end portion extending through an insert hole defined in the partition from a side on which the motor chamber lies;

the connecting shaft portion includes:

a second end portion coupled to the first end portion;

a third end portion on a side opposite to the second end portion; and

a connection flange portion extending radially outward at the third end portion;

the second shaft portion includes a fourth end portion on a side closer to the third end portion of the connecting shaft portion;

the separating mechanism selectively separates the connection flange portion and the fourth end portion from each other;

a first bearing is in a radial gap between the third end portion and the fourth end portion;

the second shaft portion includes a fifth end portion on a side opposed to the fourth end portion, the fifth end portion being rotatably supported by a second bearing which is held by the housing; and

the second shaft portion is directly supported by the first bearing and the second bearing at opposing ends of the second shaft portion in the horizontal direction.

2. The motor unit according to claim 1 , wherein

one of the third end portion and the fourth end portion includes a first recessed portion to house another one of the third end portion and the fourth end portion.

3. The motor unit according to claim 2 , wherein the first bearing is a needle bearing including a plurality of columnar members with an annular shape.

4. The motor unit according to claim 2 , wherein

the first shaft portion, the connecting shaft portion, and the second shaft portion include hollow portions extending in an axial direction and to be in communication with one another; and

the hollow portions are structured to allow an oil to cool an inside of the motor to be fed thereinto from a side on which the second shaft portion lies toward a side on which the first shaft portion lies.

5. The motor unit according to claim 1 , wherein the first end portion includes a second recessed portion, an outer circumferential surface of the second end portion being fitted to the second recessed portion.

6. The motor unit according to claim 1 , wherein the first end portion of the first shaft portion is supported by a third bearing in contact with and held by a surface of the partition facing the motor chamber.

7. The motor unit according to claim 1 , wherein the connecting shaft portion is supported by a fourth bearing in contact with and held by a surface of the partition facing the gear chamber.

8. The motor unit according to claim 7 , wherein

the fourth bearing is a ball bearing; and

the connecting shaft portion includes a shoulder surface facing toward the partition and in contact with an inner race of the fourth bearing.

9. The motor unit according to claim 1 , wherein

the first end portion of the first shaft portion is supported by a third bearing in contact with and held by a surface of the partition facing the motor chamber;

the connecting shaft portion is supported by a fourth bearing in contact with and held by a surface of the partition facing onto the gear chamber; and

the fourth bearing has an outside diameter greater than an outside diameter of the third bearing.

10. The motor unit according to claim 1 , wherein the second shaft portion includes a first gear between the fourth end portion and the fifth end portion to transfer power to the reduction gear.

11. The motor unit according to claim 10 , wherein

the reduction gear includes a second gear connected to the first gear and a third gear rotatable in synchronism with the second gear; and

the third gear and the separating mechanism axially overlap with each other.