Underwater propulsion unit

1. An underwater propulsion unit comprising:

a propeller coupled to a motor via a propeller shaft, the propeller shaft rotatably supported by a bearing, the propeller interposed between the bearing and the motor;

the motor that is disposed further forward in a propulsion direction than the propeller and is configured to drive the propeller into rotation; and

a housing configured to accommodate the motor and the propeller, the housing including:

a first portion, and

a second portion that is disposed further rearward in the propulsion direction than the first portion, and

wherein:

an introduction inlet and a spout outlet are provided in the second portion,

the introduction inlet is configured to introduce water into the housing in a direction parallel to an axis of the propeller,

the introduction inlet includes a first introduction inlet and a second introduction inlet,

with respect to the propulsion direction, a radial circumference of the housing is defined by the first introduction inlet to a third portion of the housing to the second introduction inlet and to a fourth portion of the housing,

the spout outlet is configured to allow water introduced from the introduction inlet and delivered by the propeller to be spouted out of the housing, and

when viewed in a direction parallel to the propulsion direction, the introduction inlet is disposed further outward than the first portion.

2. The underwater propulsion unit according to claim 1 , wherein:

the second portion includes a projection that projects further outward than the first portion when viewed in a direction parallel to the propulsion direction, and

the introduction inlet is disposed in a front portion of the projection in the propulsion direction.

3. The underwater propulsion unit according to claim 2 , wherein the projection projects in a direction different from a downward direction when viewed in a direction parallel to the propulsion direction.

4. The underwater propulsion unit according to claim 2 , wherein a filter configured to restrict a foreign matter from entering into the introduction inlet is disposed along a surface from which a distance to the axis of the propeller increases rearward in the propulsion direction.

5. The underwater propulsion unit according to claim 4 , wherein:

the filter includes an elongated foreign matter restricting member, and

when viewed in parallel to a direction in which the projection projects further than the first portion in the propulsion direction, the elongated foreign matter restricting member in a longitudinal direction includes at least one of a portion parallel to the axis of the propeller and a portion inclined at an angle smaller than 45° relative to the axis of the propeller.

6. The underwater propulsion unit according to claim 1 , wherein at least a portion of the motor is interposed between the introduction inlet and the first portion.

7. The underwater propulsion unit according to claim 1 , wherein at least a portion of the motor is configured to be interposed between at least a portion of the first introduction inlet and at least a portion of the second introduction inlet.

8. The underwater propulsion unit according to claim 1 , wherein with respect to a path about the radial circumference of the housing, the third portion of the housing is between the first introduction inlet and the second introduction inlet.

9. The underwater propulsion unit according to claim 8 , wherein, with respect to a path about the radial circumference of the housing:

the second introduction inlet is between the third portion of the housing and the fourth portion of the housing; and

the fourth portion of the housing is between the second introduction inlet and the first introduction inlet.

10. The underwater propulsion unit according to claim 1 , wherein each of the first introduction inlet and the second introduction inlet include a filter configured to face towards the first portion of the housing.

11. The underwater propulsion unit according to claim 1 , wherein a first diameter is defined by the housing.

12. The underwater propulsion unit according to claim 11 , wherein a second diameter defined by the first introduction inlet and the second introduction inlet is greater than the first diameter.

13. The underwater propulsion unit according to claim 12 , wherein the second diameter is defined at least in part by an inlet portion of the first introduction inlet and an inlet portion of the second introduction inlet.

14. The underwater propulsion unit according to claim 13 , wherein the inlet portion of the first introduction inlet is positioned on a propeller facing side of the first introduction inlet.

15. The underwater propulsion unit according to claim 14 , wherein the inlet portion of the second introduction inlet is positioned on a propeller facing side of the second introduction inlet.

16. The underwater propulsion unit according to claim 12 , wherein the first introduction inlet includes a first inlet portion and a second inlet portion, the second inlet portion interposed between the first inlet portion and the propeller.

17. The underwater propulsion unit according to claim 16 , wherein the second introduction inlet includes a third inlet portion and a fourth inlet portion, the fourth inlet portion interposed between the third inlet portion and the propeller.

18. The underwater propulsion unit according to claim 17 , wherein the second diameter is defined at least in part by the second inlet portion and the fourth inlet portion.

19. The underwater propulsion unit according to claim 17 , wherein the second inlet portion is configured to extend farther from the housing than the first inlet portion.

20. The underwater propulsion unit according to claim 17 , wherein the fourth inlet portion is configured to extend farther from the housing than the third inlet portion.