ELECTRIC PROPULSION MACHINE

Abstract

An electric propulsion device includes a motor for rotating a propeller and a cooling device for cooling the motor. The cooling device includes a first cooling system and a second cooling system. The first cooling system includes a heat exchanger that uses water from outside the electric propulsion device as cooling water and cools refrigerant, and a supply passage that supplies the water from outside the electric propulsion device as the cooling water to the heat exchanger. The second cooling system includes a motor cooling jacket that is provided in the motor and cools the motor with the refrigerant, and a circulation passage that circulates the refrigerant between the heat exchanger and the motor cooling jacket.

Claims

1. An electric propulsion device comprising: a motor configured to rotate a propeller; and a cooling device configured to cool the motor, wherein the cooling device includes a first cooling system and a second cooling system, the first cooling system includes: a heat exchanger that uses water from outside the electric propulsion device as cooling water and configured to cool refrigerant; and a supply passage that supplies the water from outside the electric propulsion device to the heat exchanger as the cooling water, and the second cooling system includes: a motor cooling jacket that is provided in the motor and configured to cool the motor with the refrigerant; and a circulation passage that circulates the refrigerant between the heat exchanger and the motor cooling jacket.

2. The electric propulsion device according to claim 1, further comprising: an electric propulsion device body including: the motor; a propeller shaft disposed below the motor and provided with the propeller; and a drive shaft extending in a vertical direction between the motor and the propeller shaft; and a mounting mechanism configured to mount the electric propulsion device on a boat, wherein the mounting mechanism includes a swivel bracket configured to support the electric propulsion device body to be pivotable in a left-right direction relative to the boat, and the motor and the heat exchanger are disposed below an upper end of the swivel bracket.

3. The electric propulsion device according to claim 2, wherein the mounting mechanism includes two mounts that connect each of two portions spaced from each other in the vertical direction at an upper part of the electric propulsion device body to the swivel bracket, and the heat exchanger is positioned between the two mounts in the vertical direction.

4. The electric propulsion device according to claim 1, wherein an outer shape of the heat exchanger is a cylinder or a polygonal prism with an axial dimension greater than a radial dimension, and the heat exchanger is disposed behind the motor so that the axial direction of the heat exchanger is the vertical direction of the electric propulsion device.

5. The electric propulsion device according to claim 1, further comprising: an inverter configured to control driving of the motor, wherein the second cooling system includes an inverter cooling jacket that is provided in the inverter and configured to cool the inverter using the refrigerant, and the circulation passage is a passage that circulates the refrigerant between the heat exchanger and the motor cooling jacket and the inverter cooling jacket.

6. The electric propulsion device according to claim 5, wherein the circulation passage includes: a first refrigerant passage connecting the heat exchanger to the motor cooling jacket; a second refrigerant passage connecting the motor cooling jacket to the inverter cooling jacket; and a third refrigerant passage connecting the inverter cooling jacket to the heat exchanger.

7. The electric propulsion device according to claim 5, wherein the heat exchanger is disposed behind the motor, the inverter is disposed above the motor, and the inverter cooling jacket is disposed in the rear part of the inverter.

8. The electric propulsion device according to claim 5, wherein the second cooling system includes a degassing tank that is connected to the circulation passage and configured to separates gas from the refrigerant, and the inverter is disposed above the motor and the degassing tank is disposed above the inverter.

9. The electric propulsion device according to claim 1, wherein the second cooling system includes a refrigerant pump configured to circulate the refrigerant in the circulation passage, and the refrigerant pump is disposed above the heat exchanger.

10. The electric propulsion device according to claim 1, further comprising: a propeller shaft disposed below the motor and provided with the propeller; a drive shaft extending in a vertical direction between the motor and the propeller shaft; and a case configured to accommodate an upper part or a lower part of the drive shaft, wherein the second cooling system includes: a refrigerant pump configured to circulate the refrigerant in the circulation passage; and a refrigerant reservoir provided in the case and configured to store the refrigerant circulating in the circulation passage, the circulation passage includes: a first refrigerant passage connecting the heat exchanger to the refrigerant reservoir; a second refrigerant passage connecting the refrigerant reservoir to the motor cooling jacket; and a third refrigerant passage connecting the motor cooling jacket to the heat exchanger, and the refrigerant pump circulates the refrigerant so that the refrigerant flows from the heat exchanger to the refrigerant reservoir, then from the refrigerant reservoir to the motor cooling jacket, and then from the motor cooling jacket back to the heat exchanger.

11. The electric propulsion device according to claim 1, further comprising: a drive shaft; a first transmission mechanism configured to transmit rotation of the motor to the drive shaft; a propeller shaft provided with the propeller; and a second transmission mechanism configured to transmit rotation of the drive shaft to the propeller shaft, wherein the first cooling system includes a transmission mechanism cooling jacket that uses the water from outside the electric propulsion device as the cooling water and cools the first transmission mechanism, and the supply passage is a passage that supplies the water from outside the electric propulsion device to the heat exchanger and the transmission mechanism cooling jacket as the cooling water.

12. The electric propulsion device according to claim 11, wherein the supply passage includes: a first cooling water passage connecting a water intake port that takes in the water from outside the electric propulsion device as the cooling water into the electric propulsion device to the transmission mechanism cooling jacket; and a second cooling water passage connecting the transmission mechanism cooling jacket to the heat exchanger.

13. The electric propulsion device according to claim 12, wherein the heat exchanger is disposed behind the motor, the transmission mechanism cooling jacket is disposed below the motor, one end portion of the second cooling water passage is connected to a rear part of the transmission mechanism cooling jacket, and the other end portion of the second cooling water passage is connected to a lower part of the heat exchanger.

14. The electric propulsion device according to claim 5, wherein the inverter is disposed above the motor, first ports that connect inside of the motor cooling jacket to outside of the motor cooling jacket are provided at each of both ends of the motor cooling jacket, and one of the first ports provided at the motor cooling jacket is disposed on an upper surface of the motor, and second ports that connect inside of the inverter cooling jacket to outside of the inverter cooling jacket are provided at each of both ends of the inverter cooling jacket, and one of the second ports provided at the inverter cooling jacket is disposed on a lower surface of the inverter.

15. The electric propulsion device according to claim 14, wherein, when the electric propulsion device is viewed from above, at least a portion of the one port of the inverter cooling jacket overlaps with the one port of the motor cooling jacket.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0018] FIG. 1 is an explanatory diagram illustrating an electric propulsion device according to a first example of the present invention as viewed from the left.

[0019] FIG. 2 is an explanatory diagram illustrating the electric propulsion device according to the first example of the present invention as viewed from behind.

[0020] FIG. 3 is a cross-sectional view illustrating the electric propulsion device cut along a line III-III in FIG. 2 as viewed from the left.

[0021] FIG. 4 is an exploded view of a portion of the electric propulsion device according to the first example of the present invention.

[0022] FIG. 5 is a block diagram illustrating a cooling device in the electric propulsion device according to the first example of the present invention.

[0023] FIG. 6 is an enlarged cross-sectional view illustrating a water intake port, a water pump, a speed reducer cooling jacket, a heat exchanger, and the like in the electric propulsion device in FIG. 3.

[0024] FIG. 7 is an external view of the heat exchanger provided in the electric propulsion device according to the first example of the present invention.

[0025] FIG. 8 is a cross-sectional view illustrating a motor and an inverter in the electric propulsion device cut along a line XIII-XIII in FIG. 2.

[0026] FIG. 9A is an explanatory diagram illustrating an electric propulsion device according to a second example of the present invention as viewed from the left, and FIG. 9B is an explanatory diagram illustrating a lower part of the electric propulsion device as viewed from behind.

[0027] FIG. 10 is a block diagram illustrating a cooling device in the electric propulsion device according to the second example of the present invention.

DESCRIPTION OF EMBODIMENTS

[0028] An electric propulsion device according to an embodiment of the present invention includes a motor for rotating a propeller, and a cooling device for cooling the motor. The cooling device in the electric propulsion device of the embodiment includes a first cooling system and a second cooling system. The first cooling system includes a heat exchanger that uses water from outside the electric propulsion device as cooling water and cools refrigerant, and a supply passage that supplies the water from outside the electric propulsion device to the heat exchanger as the cooling water. The second cooling system includes a motor cooling jacket that is provided in the motor and cools the motor with the refrigerant, and a circulation passage that circulates the refrigerant between the heat exchanger and the motor cooling jacket.

[0029] In the electric propulsion device of the embodiment, water (for example, seawater) from outside the electric propulsion device is supplied as the cooling water to the heat exchanger via the supply passage, and heat is exchanged between the cooling water and the refrigerant in the heat exchanger, thereby cooling the refrigerant. After cooling the refrigerant, the cooling water is discharged out of the electric propulsion device. The refrigerant cooled in the heat exchanger is supplied to the motor cooling jacket via the circulation passage, and the motor is cooled by the refrigerant flowing through the motor cooling jacket. After cooling the motor, the refrigerant returns to the heat exchanger.

[0030] As described above, in the electric propulsion device of the embodiment, when cooling the motor, water from outside the electric propulsion device does not flow through the motor cooling jacket. That is, seawater does not flow through the motor cooling jacket. Therefore, corrosion of the motor cooling jacket due to seawater can be prevented. Therefore, corrosion of the motor cooling jacket can be prevented.

First Example

[0031] Examples of the present invention will be described with reference to the drawings. In the description of each example, directions of up (Ud), down (Dd), front (Fd), back (Bd), left (Ld), and right (Rd) follow arrows drawn below in FIGS. 1 to 4, 6, 8, 9A and 9B.

Electric Propulsion Device

[0032] FIG. 1 illustrates an electric propulsion device 1 according to a first example of the present invention as viewed from the left. FIG. 2 illustrates the electric propulsion device 1 as viewed from behind. FIG. 3 illustrates a cross section of the electric propulsion device 1 cut along a line III-III in FIG. 2 as viewed from the left. FIG. 4 illustrates the electric propulsion device 1 in a partially exploded state.

[0033] The electric propulsion device 1 is an electric marine propulsion device for propelling a boat. As illustrated in FIG. 1, the electric propulsion device 1 of the example is an outboard motor and is mounted on a boat. As illustrated in FIG. 3, the electric propulsion device 1 includes an electric propulsion device body 2, where the electric propulsion device body 2 includes a motor 3, an inverter 6, a speed reducer 11, a drive shaft 14, a propeller shaft 15, a propeller 16, and a rotation transmission mechanism 17. The speed reducer 11 is a specific example of a first transmission mechanism, and the rotation transmission mechanism 17 is a specific example of a second transmission mechanism.

[0034] The motor 3 is a power source for rotating the propeller 16. The motor 3 is, for example, an AC motor, and includes an output shaft 4, a rotor, a stator, and a motor case 5. The output shaft 4 excluding an end portion that outputs rotation of the rotor, the rotor, and the stator are accommodated in the motor case 5. The motor 3 is disposed in an upper part of the electric propulsion device body 2. When the electric propulsion device 1 is mounted on the boat, the motor 3 is positioned above the water surface. The motor 3 is disposed in the electric propulsion device body 2 so that an extension direction of the output shaft 4 is a vertical direction. As illustrated in FIG. 1, the motor 3 is disposed below an upper end of a swivel bracket 33.

[0035] The inverter 6 is a device that controls driving of the motor 3. As illustrated in FIG. 3, the inverter 6 includes an inverter body 7 provided with a circuit that controls the driving of the motor 3 and the like, and an inverter case 8 that accommodates the inverter body 7. The inverter 6 is disposed above the motor 3. The inverter 6 is mounted on the motor 3 via an inverter mounting member 10.

[0036] The speed reducer 11 is a device that reduces rotation of the output shaft 4 of the motor 3 and transmits the rotation to the drive shaft 14. The speed reducer 11 is disposed below the motor 3. The speed reducer 11 includes a drive gear 12 and a driven gear 13. The drive gear 12 is coupled to a lower end of the output shaft 4 of the motor 3 and rotates integrally with the output shaft 4. The driven gear 13 is disposed in front of the drive gear 12, is coupled to an upper end of the drive shaft 14, and meshes with the drive gear 12.

[0037] The drive shaft 14 is positioned in front of the output shaft 4 of the motor 3, and extends in the vertical direction from the speed reducer 11 to the rotation transmission mechanism 17. As described above, the driven gear 13 is coupled to the upper end of the drive shaft 14 and the drive shaft 14 rotates integrally with the driven gear 13.

[0038] The propeller shaft 15 is disposed below the motor 3 and extends in a front-rear direction. The propeller 16 is mounted on a rear part of the propeller shaft 15 and rotates integrally with the propeller shaft 15. The propeller shaft 15 and the propeller 16 are disposed in a lower part of the electric propulsion device body 2. When the electric propulsion device 1 is mounted on the boat, the propeller shaft 15 and the propeller 16 are positioned below the water surface.

[0039] The rotation transmission mechanism 17 is a mechanism that transmits rotation of the drive shaft 14 to the propeller shaft 15. The rotation transmission mechanism 17 includes a transmission gear 18, a forward gear 19, a reverse gear 20, a dog clutch 21, and a shift plunger 22. The transmission gear 18, the forward gear 19, and the reverse gear 20 are all bevel gears. A rotation axis of the transmission gear 18 extends in the vertical direction. The transmission gear 18 is coupled to a lower end of the drive shaft 14 and rotates integrally with the drive shaft 14. Rotation axes of the forward gear 19 and the reverse gear 20 extend in the front-rear direction. The forward gear 19 is disposed in front of the transmission gear 18 and the reverse gear 20 is disposed behind the transmission gear 18. The forward gear 19 and the reverse gear 20 each mesh with the transmission gear 18, and upon receiving rotation of the transmission gear 18, the forward gear 19 and the reverse gear 20 rotate in opposite directions to each other. A through hole is formed in each of a center of the forward gear 19 and a center of the reverse gear 20, and a front part of the propeller shaft 15 is inserted into the through holes. The forward gear 19 and the reverse gear 20 are not fixed to the propeller shaft 15 and are rotatable relative to the propeller shaft 15. The dog clutch 21 is disposed between the forward gear 19 and the reverse gear 20. The dog clutch 21 is attached to the front part of the propeller shaft 15 to not be rotatable relative to the propeller shaft 15 and to be movable in the front-rear direction relative to the propeller shaft 15. The shift plunger 22 is a member that moves the dog clutch 21, and is attached inside a front end of the propeller shaft 15 to be movable in the front-rear direction relative to the propeller shaft 15. The electric propulsion device 1 is provided with a shift actuator 23 that controls movement of the dog clutch 21, and a shift rod 24 that transmits power from the shift actuator 23 to the shift plunger 22. The power from the shift actuator 23 is transmitted to the dog clutch 21 via the shift rod 24 and the shift plunger 22 so that the dog clutch 21 moves forward or rearward. When the dog clutch 21 moves forward, the dog clutch 21 and the forward gear 19 engage with each other, thereby transmitting rotation of the forward gear 19 to the propeller shaft 15. Meanwhile, when the dog clutch 21 moves rearward, the dog clutch 21 and the reverse gear 20 engage with each other, thereby transmitting rotation of the reverse gear 20 to the propeller shaft 15.

[0040] When the motor 3 is driven, the rotation of the output shaft 4 of the motor 3 is transmitted to the forward gear 19 and the reverse gear 20 via the drive gear 12, the driven gear 13, the drive shaft 14, and the transmission gear 18 in this order. When the dog clutch 21 is moved forward, the rotation of the forward gear 19 is transmitted to the propeller shaft 15 so that the propeller shaft 15 and the propeller 16 are rotated forward. Forward rotation of the propeller 16 generates thrust that moves the boat forward. Meanwhile, when the dog clutch 21 is moved rearward, the rotation of the reverse gear 20 is transmitted to the propeller shaft 15 so that the propeller shaft 15 and the propeller 16 are rotated reversely. Reverse rotation of the propeller 16 generates thrust that moves the boat rearward.

[0041] As illustrated in FIGS. 3 and 4, the electric propulsion device 1 includes a speed reducer case 25 that accommodates the speed reducer 11 and an upper part of the drive shaft 14. The speed reducer case 25 is disposed below the motor 3 and attached to the motor 3. The electric propulsion device 1 includes a lower case 27 that accommodates a lower part of the drive shaft 14, the front part of the propeller shaft 15, and the rotation transmission mechanism 17. The lower case 27 is disposed below the speed reducer case 25 and attached to the speed reducer case 25.

[0042] As illustrated in FIG. 1, the electric propulsion device 1 includes a mounting mechanism 30 that mounts the electric propulsion device body 2 to a boat. The mounting mechanism 30 includes a pair of left and right clamp brackets 31 that mount the electric propulsion device body 2 to a transom 101 of the boat, a pilot shaft 32 serving as an axis for pivoting the electric propulsion device body 2 in a left-right direction relative to the boat, a swivel bracket 33 that supports the pilot shaft 32 to be pivotable, a tilt shaft 34 that connects each clamp bracket 31 to the swivel bracket 33, an upper mount 35 that connects an upper end of the pilot shaft 32 to the electric propulsion device body 2, and a lower mount 36 that connects a lower end of the pilot shaft 32 to the electric propulsion device body 2.

[0043] The pair of left and right clamp brackets 31 and the swivel bracket 33 are disposed in front of the upper part of the electric propulsion device body 2. The swivel bracket 33 is disposed between the pair of clamp brackets 31. The swivel bracket 33 can pivot up and down relative to each clamp bracket 31 with the tilt shaft 34 serving as a pivot axis. Accordingly, it is possible to pivot (tilt up, tilt down) the electric propulsion device body 2 in the vertical direction relative to the boat.

[0044] The pilot shaft 32 extends in the vertical direction, and a front part of the upper mount 35 is fixed to the upper end of the pilot shaft 32. A rear part of the upper mount 35 is attached to an upper front part of the upper part of the electric propulsion device body 2, specifically, to a front part of the inverter mounting member 10. A front part of the lower mount 36 is fixed to the lower end of the pilot shaft 32. A rear part of the lower mount 36 is attached to a lower front part of the upper part of the electric propulsion device body 2, specifically, to a front part of the speed reducer case 25. As such, the electric propulsion device body 2 is connected to the pilot shaft 32 by two portions in the upper part vertically separated from each other and supported by the upper mount 35 and the lower mount 36, and the pilot shaft 32 is connected to the swivel bracket 33 by being supported by the swivel bracket 33.

Cooling Device

[0045] FIG. 5 illustrates a configuration of a cooling device 41 in the electric propulsion device 1 of the example. The cooling device 41 is a liquid-cooling type cooling device that is provided in the electric propulsion device 1 and cools equipment that needs to be cooled, that is, equipment requiring cooling. The equipment requiring cooling provided in the electric propulsion device 1 is the motor 3, the inverter 6, and the speed reducer 11.

[0046] As illustrated in FIG. 5, the cooling device 41 includes a direct cooling system 42 and an indirect cooling system 60. The direct cooling system 42 is a system that cools equipment requiring cooling or refrigerant by directly exchanging heat with water (for example, seawater) from outside the electric propulsion device 1. The indirect cooling system 60 is a system that cools equipment requiring cooling by exchanging heat with the refrigerant cooled in the direct cooling system. The refrigerant is, for example, a coolant such as LLC. The direct cooling system 42 is a specific example of a first cooling system, and the indirect cooling system 60 is a specific example of a second cooling system.

Direct Cooling System

[0047] As illustrated in FIG. 5, the direct cooling system 42 includes a water intake port 43, a speed reducer cooling jacket 44, a heat exchanger 45, a water pump 46, a supply passage, a discharge passage 55, a discharge space 56, and a drain port 57. The supply passage includes cooling water passages 51 to 53.

[0048] FIG. 6 illustrates an enlarged view of the water intake port 43, the water pump 46, the speed reducer cooling jacket 44, the heat exchanger 45, and the like in the electric propulsion device 1 in FIG. 3.

[0049] In FIG. 6, the water intake port 43 is a port for taking water from outside the electric propulsion device 1 into the electric propulsion device 1. The water intake port 43 is provided in a portion of the electric propulsion device 1 submerged below the water surface, for example, in a front part of the lower case 27 below an anti-cavitation plate 28.

[0050] The speed reducer cooling jacket 44 is a mechanism that cools the speed reducer 11 using cooling water. The speed reducer cooling jacket 44 is configured of a flow path for cooling water that passes a position near the speed reducer 11. The speed reducer cooling jacket 44 is disposed below the speed reducer 11 in the speed reducer case 25. The speed reducer cooling jacket 44 is positioned below the motor 3. The speed reducer cooling jacket 44 is positioned behind the drive shaft 14. The speed reducer cooling jacket 44 is a specific example of a transmission mechanism cooling jacket.

[0051] The heat exchanger 45 is a device that uses water from outside the electric propulsion device 1 as cooling water and cools the refrigerant. An internal cooling water flow path through which the cooling water flows and an internal refrigerant flow path through which the refrigerant flows are provided in the heat exchanger 45. The internal cooling water flow path and the internal refrigerant flow path are independent of each other but are extremely close to each other so that heat exchange is possible between the cooling water flowing in the internal cooling water flow path and the refrigerant flowing in the internal refrigerant flow path. As illustrated in FIG. 7, an outer shape of the heat exchanger 45 is a cylinder or a polygonal prism with an axial dimension Lx greater than a radial dimension Ly. As illustrated in FIG. 1, the heat exchanger 45 is disposed behind the motor 3 so that an axial direction of the heat exchanger 45 is aligned with the vertical direction of the electric propulsion device 1. The heat exchanger 45 is disposed below an upper end of the swivel bracket 33. The heat exchanger 45 is positioned between the upper mount 35 and the lower mount 36 in the vertical direction.

[0052] The water pump 46 is a pump that sends water from outside the electric propulsion device 1 taken into the electric propulsion device 1 through the water intake port 43 to the speed reducer cooling jacket 44 and the heat exchanger 45 as cooling water. The water pump 46 is, for example, a rotary variable displacement pump. As illustrated in FIG. 6, the water pump 46 includes an impeller 47 and a pump case 48 that accommodates the impeller 47. The impeller 47 is fixed to the drive shaft 14 and rotates integrally with the drive shaft 14. The pump case 48 is attached on an upper surface of the lower case 27, for example.

[0053] The supply passage is a passage that supplies water from outside the electric propulsion device 1 to the speed reducer cooling jacket 44 and the heat exchanger 45 as cooling water. The supply passage includes the cooling water passage 51 connecting the water intake port 43 to a suction port of the water pump 46, the cooling water passage 52 connecting a discharge port 48A of the water pump 46 to the speed reducer cooling jacket 44, and the cooling water passage 53 connecting the speed reducer cooling jacket 44 to the heat exchanger 45.

[0054] The cooling water passage 51 is configured by, for example, a hole formed in the lower case 27 and extending in the vertical direction. The cooling water passage 52 is formed by, for example, a tubular member attached to a portion inside the speed reducer case 25. The cooling water passages 51 and 52 correspond to cooling water passages that connect the water intake port 43 to the speed reducer cooling jacket 44.

[0055] The cooling water passage 53 is formed by, for example, a hose or a pipe. As can be viewed from FIGS. 2 and 3, the cooling water passage 53 is disposed outside the speed reducer case 25. An inlet end of the cooling water passage 53 is connected to a rear part of the speed reducer cooling jacket 44. Specifically, a connection port 54 that communicates with the inside of the speed reducer cooling jacket 44 opens on a rear surface of the speed reducer case 25. The inlet end of the cooling water passage 53 is connected to the connection port 54. An outlet end of the cooling water passage 53 is connected to an inlet port of the internal cooling water flow path provided in a lower part of the heat exchanger 45. The cooling water passage 53 extends rearward from the connection port 54, then bends upward, and then extends upward to reach the lower part of the heat exchanger 45.

[0056] The discharge passage 55 is a passage that carries the cooling water after flowing through the internal cooling water flow path of the heat exchanger 45 to the drain port 57. As illustrated in FIGS. 1 and 2, the discharge passage 55 is formed by, for example, a hose or a pipe. An inlet end of the discharge passage 55 is connected to an outlet port of the internal cooling water flow path provided in the lower part of the heat exchanger 45. As illustrated in FIG. 3, the discharge space 56 is provided from a lower rear part in the speed reducer case 25 to a rear part in the lower case 27, and as illustrated in FIG. 1, a discharge space inlet port 56A that communicates with the inside of the discharge space 56 opens on a left surface of the speed reducer case 25. An outlet end of the discharge passage 55 is connected to the discharge space inlet port 56A and communicates with the inside of the discharge space 56 via the discharge space inlet port 56A.

[0057] The drain port 57 is a port for discharging cooling water after flowing through the heat exchanger 45 out of the electric propulsion device 1. The drain port 57 is formed in, for example, a hub of the propeller 16. The drain port 57 communicates with the inside of the discharge space 56.

[0058] In FIG. 6, when the drive shaft 14 rotates and the water pump 46 is driven, water from outside the electric propulsion device 1 taken into the electric propulsion device 1 through the water intake port 43 flows through the cooling water passage 51 as cooling water, is sucked into the water pump 46, and is then discharged from the discharge port 48A of the water pump 46. The cooling water discharged from the discharge port 48A of the water pump 46 flows through the cooling water passage 52 and then flows through the speed reducer cooling jacket 44. The speed reducer 11 is cooled by the cooling water flowing through the speed reducer cooling jacket 44. After flowing through the speed reducer cooling jacket 44, the cooling water flows through the cooling water passage 53 and then flows through the internal cooling water flow path of the heat exchanger 45. The cooling water flows through the internal cooling water flow path of the heat exchanger 45 so that the refrigerant circulating through a circulation passage of the indirect cooling system 60 is cooled. After flowing through the internal cooling water flow path of the heat exchanger 45, the cooling water flows through the discharge passage 55 (see FIG. 1), then flows through the discharge space 56 (see FIG. 3), and then is discharged out of the electric propulsion device 1 through the drain port 57.

Indirect Cooling System

[0059] As illustrated in FIG. 5, the indirect cooling system 60 includes a motor cooling jacket 61, an inverter cooling jacket 62, a refrigerant pump 63, a degassing tank 64, and the circulation passage. The circulation passage includes refrigerant passages 71 to 76.

[0060] The motor cooling jacket 61 is a mechanism that cools the motor 3 using refrigerant. The motor cooling jacket 61 is provided in the motor 3 as illustrated in FIG. 3. For example, the motor cooling jacket 61 is configured by a flow path formed in the motor case 5 of the motor 3. The flow path configuring the motor cooling jacket 61 is formed across a wide range of the motor case 5. For example, the flow path is formed around the entire circumference of the motor case 5 and from one end portion to the other end portion of the motor case 5 in an axial direction. One end portion of the motor cooling jacket 61 is provided with an inlet port 61A serving as a port connecting the inside of the motor cooling jacket 61 to the outside of the motor cooling jacket 61 and allows the refrigerant to flow into the motor cooling jacket 61. The inlet port 61A opens at a lower rear part of the motor case 5. The other end portion of the motor cooling jacket 61 is provided with an outlet port 61C serving as a port connecting the inside of the motor cooling jacket 61 to the outside of the motor cooling jacket 61 and allows the refrigerant after flowing through the motor cooling jacket 61 to flow out of the motor cooling jacket 61. The outlet port 61C opens on a rear left part of an upper surface 5A of the motor case 5 as will be described below with reference to FIG. 8.

[0061] The inverter cooling jacket 62 is a mechanism that cools the inverter 6 using refrigerant. The inverter cooling jacket 62 is provided in the inverter 6 as illustrated in FIG. 3. For example, the inverter cooling jacket 62 is disposed at a lower rear part of the inverter 6 and is positioned below a rear part of the inverter body 7. Specifically, the inverter cooling jacket 62 is configured by a flow path formed in a lower rear part of the inverter case 8. The flow path extends from a left end to a right end of the inverter case 8. One end portion of the inverter cooling jacket 62 is provided with an inlet port 62A serving as a port connecting the inside of the inverter cooling jacket 62 to the outside of the inverter cooling jacket 62 and allows the refrigerant to flow into the inverter cooling jacket 62. As will be described below with reference to FIG. 8, the inlet port 62A opens on a left end portion of a lower surface 8A at a rear part of the inverter case 8. The other end portion of the inverter cooling jacket 62 is provided with an outlet port serving as a port connecting the inside of the inverter cooling jacket 62 to the outside of the inverter cooling jacket 62 and allows the refrigerant after flowing through the inverter cooling jacket 62 to flow out of the inverter cooling jacket 62. Although not illustrated in detail, the outlet port is open on a right surface of the lower rear part of the inverter case 8.

[0062] The refrigerant pump 63 is a pump that circulates the refrigerant in the circulation passage. The refrigerant pump 63 is an electric pump, and is driven by a motor dedicated for the refrigerant pump 63 and different from the motor 3, for example. As illustrated in FIG. 1, the refrigerant pump 63 is disposed above the heat exchanger 45. The refrigerant pump 63 is disposed behind the inverter 6. The refrigerant pump 63 is attached to a rear part of the inverter 6. The refrigerant pump 63 can adjust a flow rate of the refrigerant, for example, by changing a rotation speed of the motor dedicated for the refrigerant pump 63. Accordingly, it is possible to control a temperature of the refrigerant.

[0063] The degassing tank 64 is a tank that has a function of separating gas from the refrigerant. Specifically, the degassing tank 64 has a function of releasing air bubbles generated in the refrigerant due to heat or the like, and a function as a reserve tank to absorb any increase or decrease in the amount of the refrigerant due to thermal expansion or aging of the refrigerant. The degassing tank 64 is disposed above the inverter 6 and attached to the inverter 6. Specifically, the inverter case 8 is provided with a plurality of degassing tank attachment portions 9 that protrude upward from an upper surface thereof. The degassing tank 64 is attached to upper ends of the degassing tank attachment portions 9 using fastening members such as bolts.

[0064] The circulation passage is a passage that circulates the refrigerant between the heat exchanger 45 and the motor cooling jacket 61 and the inverter cooling jacket 62. In the indirect cooling system 60 of the example, the heat exchanger 45, the motor cooling jacket 61, and the inverter cooling jacket 62 are connected in series in this order via the circulation passage. The circulation passage includes a refrigerant passage 71 connecting the heat exchanger 45 to the motor cooling jacket 61, a refrigerant passage 72 connecting the motor cooling jacket 61 to the inverter cooling jacket 62, a refrigerant passage 73 connecting the inverter cooling jacket 62 to a refrigerant passage connection portion 77, a refrigerant passage 74 connecting the refrigerant passage connection portion 77 to the refrigerant pump 63, a refrigerant passage 75 connecting the refrigerant pump 63 to the heat exchanger 45, and a refrigerant passage 76 connecting the refrigerant passage connection portion 77 to the degassing tank 64.

[0065] As illustrated in FIGS. 1 and 2, the refrigerant passage 71 extends from an upper left side of the heat exchanger 45 to a lower rear side of the motor 3. The refrigerant passage 71 is formed by, for example, a hose or a pipe. An inlet end of the refrigerant passage 71 is connected to an outlet port of the internal refrigerant flow path that opens on a left surface of an upper part of the heat exchanger 45. An outlet end of the refrigerant passage 71 is connected to the inlet port 61A (see FIG. 4) of the motor cooling jacket 61 that opens at the lower rear part of the motor case 5.

[0066] The refrigerant passage 72 is provided in a portion from an upper rear left part of the motor case 5 to a lower rear left part of the inverter case 8. FIG. 8 illustrates a cross section of the upper rear left part of the motor 3 and a cross section of a lower rear left part of the inverter 6 in the electric propulsion device 1 cut along a line XIII-XIII in FIG. 2. As illustrated in FIG. 8, an outlet end portion (terminal end portion) 61B of a flow path configuring the motor cooling jacket 61 is formed in the upper rear left part of the motor case 5. The outlet end portion 61B extends in the vertical direction, and an upper end thereof opens on the rear left part of the upper surface 5A (upper surface of the motor 3) of the motor case 5. The opening at an upper end side of the outlet end portion 61B is the outlet port 61C of the motor cooling jacket 61. Meanwhile, a cylindrical portion 62B is provided on a left end portion of a lower surface 8A of the rear part of the inverter case 8 and protrudes downward from the portion. The inside of the cylindrical portion 62B communicates with the inside of the inverter cooling jacket 62. An opening at a lower end side of the cylindrical portion 62B serves as the inlet port 62A of the inverter cooling jacket 62. When the electric propulsion device 1 is viewed from above, at least a portion of the inlet port 62A of the inverter cooling jacket 62 overlaps with the outlet port 61C of the motor cooling jacket 61. The refrigerant passage 72 is configured by, for example, a linear hole that penetrates a rear left part of the inverter mounting member 10 in the vertical direction. A lower end (inlet end) of the refrigerant passage 72 is connected to the outlet port 61C of the motor cooling jacket 61, and an upper end (outlet end) of the refrigerant passage 72 is connected to the inlet port 62A of the inverter cooling jacket 62.

[0067] As illustrated in FIG. 2, the refrigerant passage 73 is disposed on the rear right of the inverter 6. The refrigerant passage 73 is formed by, for example, a hose or a pipe. An inlet end of the refrigerant passage 73 is connected to the outlet port of the inverter cooling jacket 62 that opens on the right surface of the lower rear part of the inverter case 8. An outlet end of the refrigerant passage 73 is connected to the refrigerant passage connection portion 77. The refrigerant passage connection portion 77 is a portion that connects the outlet end of the refrigerant passage 73, an inlet end of the refrigerant passage 74, and a lower end of the refrigerant passage 76 to each other, and is formed by, for example, a T-shaped joint.

[0068] The refrigerant passage 74 is disposed on the right of the refrigerant pump 63. The refrigerant passage 74 is formed by, for example, a pipe. The inlet end of the refrigerant passage 74 is connected to the refrigerant passage connection portion 77. An outlet end of the refrigerant passage 74 is connected to a suction port of the refrigerant pump 63 provided on a right surface of the refrigerant pump 63.

[0069] The refrigerant passage 75 extends from a lower right side of the refrigerant pump 63 to a lower right side of the heat exchanger 45. The refrigerant passage 75 is formed by, for example, a hose or a pipe. An inlet end of the refrigerant passage 75 is connected to a discharge port of the refrigerant pump 63 provided at a lower right part of the refrigerant pump 63. An outlet end of the refrigerant passage 75 is connected to an inlet port of the internal refrigerant flow path that opens on a right surface of the lower part of the heat exchanger 45. The refrigerant passages 73, 74, and 75 correspond to the refrigerant passages connecting the inverter cooling jacket 62 to the heat exchanger 45.

[0070] The refrigerant passage 76 is disposed above a rear right part of the inverter 6 and behind a right part of the degassing tank 64. The refrigerant passage 76 is formed by, for example, a hose or a pipe. The lower end of the refrigerant passage 76 is connected to the refrigerant passage connection portion 77. An upper end of the refrigerant passage 76 is connected to a connection port provided at a rear right part of the degassing tank 64.

[0071] When the refrigerant pump 63 is driven, the refrigerant cooled by the heat exchanger 45 flows out from the outlet port of the internal refrigerant flow path of the heat exchanger 45, flows through the refrigerant passage 71, and then flows through the motor cooling jacket 61. The motor 3 is cooled by the refrigerant flowing through the motor cooling jacket 61. After flowing through the motor cooling jacket 61, the refrigerant flows through the refrigerant passage 72 and then flows through the inverter cooling jacket 62. The refrigerant flows through the inverter cooling jacket 62 and cools the inverter body 7. After flowing through the inverter cooling jacket 62, the refrigerant flows through the refrigerant passage 73, the refrigerant passage connection portion 77, the refrigerant passage 74, the refrigerant pump 63, and the refrigerant passage 75 in this order, and then flows into the internal refrigerant flow path of the heat exchanger 45 from the inlet port of the internal refrigerant flow path of the heat exchanger 45. The refrigerant of which the temperature rose due to heat from the motor 3 and the inverter 6 is cooled in the heat exchanger 45 by cooling water taken in from outside the electric propulsion device 1.

[0072] The refrigerant is stored in the degassing tank 64. Air bubbles in the refrigerant move into the degassing tank 64 via the refrigerant passage 76 and are released to the atmosphere, for example, via a gas vent passage formed in the degassing tank 64. When the amount of refrigerant flowing through the circulation passage decreases, a cap 65 of the degassing tank 64 can be removed and refrigerant can be injected into the degassing tank 64 to replenish the refrigerant.

[0073] As described above, the cooling device 41 provided in the electric propulsion device 1 of the first example of the present invention includes the direct cooling system including the heat exchanger 45 that cools the refrigerant using water from outside the electric propulsion device 1 and the supply passage that supplies the water from outside the electric propulsion device 1 to the heat exchanger 45 and cooling the refrigerant by exchanging heat with the water from outside the electric propulsion device 1, and the indirect cooling system 60 including the motor cooling jacket 61 that cools the motor 3 using the refrigerant and the circulation passage that circulates the refrigerant between the heat exchanger 45 and the motor cooling jacket 61 and cooling the motor 3 by exchanging heat with the refrigerant cooled in the direct cooling system. In the cooling device 41 having such configuration, when cooling the motor 3, water from outside the electric propulsion device 1 does not flow through the motor cooling jacket 61. That is, seawater does not flow through the motor cooling jacket 61. Therefore, corrosion of the motor cooling jacket 61 due to seawater can be prevented. Therefore, corrosion of the motor cooling jacket 61 can be prevented.

[0074] In the electric propulsion device 1 of the example, the motor 3 and the heat exchanger 45 are disposed below the upper end of the swivel bracket 33. By such configuration, the center of gravity of the electric propulsion device 1 can be lowered, and stability of mounting the electric propulsion device 1 on the boat can be improved. The electric propulsion device 1 can be prevented from protruding upward, and the electric propulsion device 1 can be prevented from obstructing visibility of behind the boat.

[0075] In the electric propulsion device 1 of the example, the heat exchanger 45 is positioned between the upper mount 35 and the lower mount 36 in the vertical direction. By such configuration, the center of gravity of the electric propulsion device 1 can be positioned between the upper mount 35 and the lower mount 36 in the vertical direction. By lowering the center of gravity of the electric propulsion device 1 as such, the stability of mounting the electric propulsion device 1 on the boat can be improved.

[0076] In the electric propulsion device 1 of the example, the outer shape of the heat exchanger 45 is a cylinder or a polygonal prism with the axial dimension greater than the radial dimension. The heat exchanger 45 is disposed behind the motor 3 so that the axial direction of the heat exchanger 45 is aligned with the vertical direction of the electric propulsion device 1. By such configuration, the center of gravity of the heat exchanger 45 can be brought closer to the boat so that the center of gravity of the electric propulsion device 1 can be brought closer to the boat, thereby improving the stability of mounting the electric propulsion device 1 on the boat.

[0077] The indirect cooling system 60 in the cooling device 41 provided in the electric propulsion device 1 of the example includes the motor cooling jacket 61 that cools the motor 3 using the refrigerant, the inverter cooling jacket 62 that cools the inverter 6 using the refrigerant, and the circulation passage that circulates the refrigerant between the heat exchanger 45 and the motor cooling jacket 61 and the inverter cooling jacket 62. By such configuration, when cooling the motor 3 and the inverter 6, the water from outside the electric propulsion device 1 does not flow through the motor cooling jacket 61 and does not flow through the inverter cooling jacket 62. That is, seawater does not flow through the motor cooling jacket 61 and seawater does not flow through the inverter cooling jacket 62. Therefore, it is possible to prevent corrosion of the motor cooling jacket 61 and the inverter cooling jacket from seawater. Therefore, corrosion of the motor cooling jacket 61 and corrosion of the inverter cooling jacket 62 can be prevented.

[0078] In the electric propulsion device 1 of the example, the heat exchanger 45 is disposed behind the motor 3, the inverter 6 is disposed above the motor 3, and the inverter cooling jacket 62 is disposed in the rear part of the inverter 6. By such configuration, each of a distance between the motor 3 and the heat exchanger 45, a distance between the motor 3 and the inverter 6, a distance between the inverter cooling jacket 62 and the heat exchanger 45, and a distance between the inverter cooling jacket 62 and the motor 3 can be shortened. Therefore, the circulation passage in the indirect cooling system 60 can be shortened. Accordingly, pressure loss occurring when the refrigerant flows through the circulation passage can be reduced, and the flow of the refrigerant in the indirect cooling system 60 can be smoothened.

[0079] In the electric propulsion device 1 of the example, the indirect cooling system 60 in the cooling device 41 includes the degassing tank 64 connected to the circulation passage, the inverter 6 is disposed above the motor 3, and the degassing tank 64 is disposed above the inverter 6. By such configuration, the degassing tank 64 can be disposed at a high position in the electric propulsion device 1. Accordingly, air bubbles in the refrigerant are easily released to the atmosphere.

[0080] In the cooling device 41 provided in the electric propulsion device 1 of the example, the indirect cooling system 60 includes the refrigerant pump 63 that circulates the refrigerant in the circulation passage, and the refrigerant pump 63 is disposed above the heat exchanger 45. By such configuration, a person performing maintenance on the electric propulsion device 1 can tilt up the electric propulsion device 1 and easily perform maintenance on the refrigerant pump 63.

[0081] In the cooling device 41 provided in the electric propulsion device 1 of the example, the direct cooling system 42 includes the speed reducer cooling jacket 44 that cools the speed reducer 11 using the water from outside the electric propulsion device 1, and the supply passage in the direct cooling system 42 is a passage that supplies the water from outside the electric propulsion device 1 to the heat exchanger 45 and the speed reducer cooling jacket 44. According to such configuration, the water from outside the electric propulsion device 1 can be used to cool both the refrigerant and the speed reducer 11.

[0082] In the electric propulsion device 1 of the example, the heat exchanger 45 is disposed behind the motor 3, the speed reducer cooling jacket 44 is disposed below the motor 3, the inlet end of the cooling water passage 53 connecting the speed reducer cooling jacket 44 to the heat exchanger 45 is connected to the rear part of the speed reducer cooling jacket 44, and the outlet end of the cooling water passage 53 is connected to the lower part of the heat exchanger 45. By such configuration, the cooling water passage 53 can be shortened. Accordingly, pressure loss occurring when the cooling water flows through the cooling water passage 53 can be reduced, and the flow of the cooling water in the direct cooling system 42 can be smoothened.

[0083] In the electric propulsion device 1 of the example, the inverter 6 is disposed above the motor 3, the outlet port 61C of the motor cooling jacket 61 is disposed on the upper surface 5A of the motor case 5 (the upper surface of the motor 3), and the inlet port 62A of the inverter cooling jacket 62 is disposed on the lower surface 8A of the inverter case 8 (the lower surface of the inverter 6). By such configuration, the refrigerant passage 72 connecting the outlet port 61C of the motor cooling jacket 61 to the inlet port 62A of the inverter cooling jacket 62 can be shortened. Accordingly, pressure loss occurring when the refrigerant flows through the refrigerant passage 72 can be reduced, and the circulation of the refrigerant in the indirect cooling system 60 can be smoothened.

[0084] When the electric propulsion device 1 of the example is viewed from above, at least a portion of the inlet port 62A of the inverter cooling jacket 62 overlaps with the outlet port 61C of the motor cooling jacket 61. By such configuration, an extension shape of the refrigerant passage 72 can be made straight or close to straight. Accordingly, smoothening of the flow of the refrigerant in the indirect cooling system 60 can be promoted.

Second Example

[0085] FIG. 9A illustrates an electric propulsion device 81 according to a second example of the present invention as viewed from the left. FIG. 9B illustrates a lower part of the electric propulsion device 81 as viewed from behind. FIG. 10 illustrates a configuration of a cooling device 85 provided in the electric propulsion device 81 according to the second embodiment of the present invention. In the electric propulsion device 81 according to the second example of the present invention, components similar to those in the electric propulsion device 1 according to the first example of the present invention are given the same reference numerals, and descriptions thereof will be simplified or omitted.

[0086] In FIG. 10, compared to the cooling device 41 in the first example of the present invention, the cooling device 85 in the second example of the present invention further includes a refrigerant reservoir 87 as a component of an indirect cooling system 86. The refrigerant reservoir 87 stores the refrigerant that circulates in a circulation passage of the indirect cooling system 86.

[0087] As illustrated in FIG. 9A, in the electric propulsion device 81, the refrigerant reservoir 87 is provided in a portion from a lower rear part in a speed reducer case 82 to a rear part in a lower case 83. Specifically, as illustrated in FIG. 3, in the electric propulsion device 1 according to the first example of the present invention, the discharge space 56 is provided in a portion from the lower rear part in the speed reducer case 25 to the rear part of the lower case 27. In the electric propulsion device 81 according to the second example of the present invention, as illustrated in FIG. 9A, a portion corresponding to the discharge space 56 of the electric propulsion device 1 according to the first example of the present invention is divided into two parts, for example, front and rear parts, and the refrigerant reservoir 87 is provided in the front part of the two parts and a discharge space 84 is provided in the rear part of the two parts. The speed reducer case 82 and the lower case 83 are specific examples of a case.

[0088] As can be understood by comparing FIG. 9A to FIG. 1, in the circulation passage of the indirect cooling system 86 of the cooling device 85 according to the second example of the present invention, the refrigerant passage 71 connecting the heat exchanger 45 to the motor cooling jacket 61 in the indirect cooling system 60 of the cooling device 41 according to the first example of the present invention is replaced with a refrigerant passage 91 connecting the heat exchanger 45 to the refrigerant reservoir 87 and a refrigerant passage 92 connecting the refrigerant reservoir 87 to the motor cooling jacket 61.

[0089] An inlet end of the refrigerant passage 91 is connected to the outlet port of the internal refrigerant flow path that opens on the left surface of the upper part of the heat exchanger 45. A refrigerant reservoir inlet port that communicates with the refrigerant reservoir 87 opens on a left surface of the speed reducer case 25. An outlet end of the refrigerant passage 91 is connected to the refrigerant reservoir inlet port.

[0090] A refrigerant reservoir outlet port that communicates with the refrigerant reservoir 87 opens on the left surface of the speed reducer case 25. An inlet end of the refrigerant passage 92 is connected to the refrigerant reservoir outlet port. An outlet end of the refrigerant passage 92 is connected to the inlet port 61A of the motor cooling jacket 61 that opens at the lower rear part of the motor case 5.

[0091] In the indirect cooling system 86 of the cooling device 85 according to the second example of the present invention, the refrigerant reservoir 87 is filled with refrigerant. When the refrigerant pump 63 is driven, the refrigerant in the refrigerant reservoir 87 flows into the refrigerant passage 92, flows through the refrigerant passage 92, and then flows through the motor cooling jacket 61. The motor 3 is cooled by the refrigerant flowing through the motor cooling jacket 61. After flowing through the motor cooling jacket 61, the refrigerant flows through the refrigerant passage 72 and then flows through the inverter cooling jacket 62. The refrigerant flows through the inverter cooling jacket 62 and cools the inverter body 7. After flowing through the inverter cooling jacket 62, the refrigerant flows through the refrigerant passage 73, the refrigerant passage connection portion 77, the refrigerant passage 74, the refrigerant pump 63, and the refrigerant passage 75 in this order, and then flows into the internal refrigerant flow path of the heat exchanger 45. The refrigerant of which the temperature rose due to the heat from the motor 3 and the inverter 6 is cooled in the heat exchanger 45. The refrigerant cooled in the heat exchanger 45 flows out from the outlet port of the internal refrigerant flow path of the heat exchanger 45, flows through the refrigerant passage 91, and flows into the refrigerant reservoir 87.

[0092] According to the cooling device 85 of the second example of the present invention having such configuration, the refrigerant can be stored in the refrigerant reservoir 87 so that the amount of refrigerant circulating in the circulation passage can be increased. Therefore, heat capacity of the refrigerant can be increased. Accordingly, it is possible to stabilize cooling capacity of the motor 3 and the inverter 6 in the indirect cooling system 60. More specifically, for example, when a rotation speed of the motor 3 is set to an extremely low level and the boat is moved at an extremely slow speed, a rotation speed of the impeller 47 of the water pump 46 of the direct cooling system 42 that rotates integrally with the drive shaft 14 becomes extremely low. As a result, a flow rate of the cooling water from the water pump 46 decreases, and there is a concern of shortage of the cooling water supplied to the heat exchanger 45 or decrease in cooling capacity of the refrigerant in the heat exchanger 45. However, even while cooling capacity of the refrigerant by the heat exchanger 45 decreases, when heat capacity of the refrigerant is large, decrease in cooling capacity of the refrigerant for the motor 3 and the inverter 6 can be delayed. Therefore, cooling capacity of the indirect cooling system 60 for the motor 3 and the inverter 6 can be stabilized.

[0093] In each of the above examples, although the refrigerant is circulated in the indirect cooling system 60 (86) in the order of the heat exchanger 45, the motor cooling jacket 61, and the inverter cooling jacket 62, the refrigerant may be circulated in the order of the heat exchanger 45, the inverter cooling jacket 62, and the motor cooling jacket 61, for example, by reversing a rotation direction of the impeller of the refrigerant pump 63 and reversing a flow direction of the refrigerant in the circulation passage.

[0094] In each of the above examples, a case where the motor 3 and the inverter 6 are cooled in the indirect cooling system 60 (86) is exemplified, but the present invention is not limited thereto. For example, only the motor 3 or only the inverter 6 may be cooled in the indirect cooling system 60 (86), or equipment other than the motor 3 and the inverter 6 may be added as equipment to be cooled in the indirect cooling system 60 (86).

[0095] In the above second example, although the refrigerant reservoir 87 in the electric propulsion device 81 is provided in the portion from the lower rear part in the speed reducer case 82 to the rear part of the lower case 83, the position where the refrigerant reservoir is provided in the electric propulsion device of the present invention is not limited. For example, the refrigerant reservoir may be provided only in the speed reducer case 82 that accommodates the upper part of the drive shaft 14, or the refrigerant reservoir may be provided only in the lower case 83 that accommodates the lower part of the drive shaft 14.

[0096] The electric propulsion device 1 (81) in each of the above examples is an outboard motor, but the present invention can also be applied to other types of electric marine propulsion devices such as an inboard-outboard motor.

[0097] The present invention can be modified as appropriate without departing from the spirit or the concept of the invention as can be read from the claims and the entire specification, and electric propulsion devices incorporating such modifications are also included in the technical concept of the present invention.