electric propulsion

Abstract

Prevents corrosion of the cooling jacket. [Solution] The electric propulsion unit (1) comprises a motor (3) that rotates a propeller (21), a propeller shaft (18) that is arranged below the motor (3) and has the propeller (21) mounted at its rear, a lower case (27) that houses the front part of the propeller shaft (18), and a cooling device that cools the motor (3). The cooling device comprises a heat exchanger (55) that uses water outside the electric propulsion unit (1) as cooling water to cool the refrigerant, a motor cooling jacket (72) that is arranged on the motor (3) and uses the refrigerant to cool the motor (3), and a circulation passage that circulates the refrigerant between the heat exchanger (55) and the motor cooling jacket (72), and the heat exchanger (55) is arranged within the lower case (27).

Description

[Technical Field]

[0001] The present invention relates to an electric propulsion device for propelling a vessel. [Background technology]

[0002] Electric marine propulsion devices, i.e., electric propulsion devices, are known that include a motor (electric motor) as a power source for rotating a propeller. Some electric propulsion devices include a cooling jacket for the motor, and a cooling device that draws water from outside the electric propulsion device (e.g., seawater) into the electric propulsion device and flows that water as cooling water through the cooling jacket of the motor to cool the motor. For example, Japanese Patent Application Laid-Open Publication No. 2005-162055 describes such an electric propulsion device. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-162055 Summary of the Invention [Problem to be solved by the invention]

[0004] However, when seawater is passed through a metal cooling jacket to cool a motor, the cooling jacket corrodes due to the seawater. Compared to, for example, pipes connected to a pump that draws seawater, the flow passages in the cooling jacket are smaller in diameter and more complex, and the walls surrounding the flow passages are thinner, so corrosion can quickly damage the cooling jacket, potentially causing leakage of cooling water.

[0005] The present invention has been made in view of the problems described above, and an object of the present invention is to provide an electric propulsion device that can suppress corrosion of the cooling jacket. [Means for solving the problem]

[0006] In order to solve the above problems, the present invention provides an electric propulsion unit comprising: a motor that rotates a propeller; a propeller shaft that is arranged below the motor and has the propeller mounted at its rear; a lower case that houses the front part of the propeller shaft; and a cooling device that cools the motor, wherein the cooling device comprises a heat exchanger that uses water outside the electric propulsion unit as cooling water to cool a refrigerant; a motor cooling jacket that is arranged on the motor and cools the motor using the refrigerant; and a circulation passage that circulates the refrigerant between the heat exchanger and the motor cooling jacket, and the heat exchanger is arranged within the lower case. [Effects of the Invention]

[0007] According to the present invention, corrosion of the cooling jacket can be suppressed. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is an explanatory diagram showing an electric propulsion device according to a first embodiment of the present invention as viewed from the left. [Figure 2] 1 is an explanatory diagram showing an electric propulsion device according to a first embodiment of the present invention as viewed from behind. [Figure 3] 3 is a cross-sectional view showing the electric propulsion taken along the cutting line AA in FIG. 2. [Figure 4] 1 is a block diagram showing the configuration of a cooling device in an electric propulsion device according to a first embodiment of the present invention. [Figure 5] 2 is an explanatory diagram showing the lower part of the lower case of the electric propulsion device according to the first embodiment of the present invention as viewed from the front. FIG. [Figure 6] 1 is a cross-sectional view showing a longitudinal section of a heat exchanger in a cooling device for an electric propulsion according to a first embodiment of the present invention. [Figure 7](A) is an external view of the heat exchanger in Figure 6 as seen from the front, (B) is a cross-sectional view of the heat exchanger cut along cutting line BB in Figure 6 as seen from the front, (C) is a cross-sectional view of the heat exchanger cut along cutting line CC in Figure 6 as seen from the front, (D) is a cross-sectional view of the heat exchanger cut along cutting line DD in Figure 6 as seen from the front, and (E) is an external view of the heat exchanger in Figure 6 as seen from the back. [Figure 8] 4 is an enlarged cross-sectional view showing a portion of the electric propulsion machine in FIG. 3 where a heat exchanger is provided. FIG. [Figure 9] FIG. 5 is a block diagram showing the configuration of a cooling device in an electric propulsion device according to a second embodiment of the present invention. [Figure 10] FIG. 10 is an explanatory diagram showing the arrangement of two heat exchangers in an electric propulsion device according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0009] An electric propulsion according to an embodiment of the present invention includes a motor that rotates a propeller, a propeller shaft that is disposed below the motor and has a propeller mounted at its rear, a lower case that houses the front portion of the propeller shaft, and a cooling device that cools the motor. In the electric propulsion according to this embodiment, the cooling device includes a heat exchanger that uses water outside the electric propulsion as cooling water to cool a refrigerant, a motor cooling jacket that is disposed on the motor and cools the motor using the refrigerant, and a circulation passage that circulates the refrigerant between the heat exchanger and the motor cooling jacket. In the electric propulsion according to this embodiment, the heat exchanger is disposed within the lower case.

[0010] In the cooling device provided in the electric propulsion of this embodiment, the heat exchanger cools the refrigerant using water (e.g., seawater) outside the electric propulsion. The motor cooling jacket cools the motor using the refrigerant that is cooled by the heat exchanger and circulates within the circulation passage. Because the motor cooling jacket cools the motor using the refrigerant circulating within the circulation passage, water outside the electric propulsion does not flow within the motor cooling jacket. In other words, seawater does not flow within the motor cooling jacket. Therefore, with the electric propulsion of this embodiment, it is possible to prevent the motor cooling jacket from corroding due to seawater, and therefore to suppress corrosion of the motor cooling jacket.

[0011] Furthermore, in the electric propulsion unit of this embodiment, the heat exchanger is provided inside the lower case. Heat exchangers are generally heavy, and if the heat exchanger were provided on top of the electric propulsion unit, the center of gravity of the electric propulsion unit would be higher, which could reduce the stability of the electric propulsion unit when it is installed on a boat. However, with the electric propulsion unit of this embodiment, the heat exchanger is provided inside the lower case, so it can be positioned below the electric propulsion unit. This allows the center of gravity of the electric propulsion unit to be lowered, improving the stability of the electric propulsion unit when installed on a boat. [Example]

[0012] Several embodiments of the present invention will be described with reference to the drawings. In the description of each embodiment, the directions of up (Ud), down (Dd), front (Fd), back (Bd), left (Ld), and right (Rd) are indicated by the arrows at the bottom left of Figures 1 to 3, 5, 6, 8, and 10.

[0013] (Electric propulsion machine) Fig. 1 shows an electric propulsion device 1 according to a first embodiment of the present invention as seen from the left. Fig. 2 shows the electric propulsion device 1 as seen from the rear. Fig. 3 shows a cross section of the electric propulsion device 1 taken along the cutting line AA in Fig. 2 as seen from the left.

[0014] The electric propulsion unit 1 is a device that propels a boat. As shown in Fig. 1, the electric propulsion unit 1 of this embodiment is an outboard motor that is attached to the transom of the boat. As shown in Fig. 3, the electric propulsion unit 1 includes a motor 3, an inverter 6, a reduction gear 11, a drive shaft 14, a rotation transmission mechanism 15, a propeller shaft 18, and a propeller 21.

[0015] The motor 3 is a power source that rotates the propeller 21, and is, for example, an AC motor. The motor 3 includes an output shaft 4, a rotor, and a stator. The motor 3 also includes a motor case 5. The output shaft 4, excluding the end from which output is taken out, as well as the rotor and stator, are housed within the motor case 5. The motor 3 is also disposed above the electric propulsion unit 1. When the electric propulsion unit 1 is attached to the boat, the motor 3 is located above the water surface. The motor 3 is also disposed so that the extension direction of the output shaft 4 is vertical.

[0016] The inverter 6 is a device that controls the driving of the motor 3. The inverter 6 includes an inverter main body 7 that is provided with circuits and the like that control the driving of the motor 3, and an inverter case 8 that houses the inverter main body 7. The inverter 6 is disposed above the motor 3. The inverter 6 is also attached to the motor 3 via an inverter mounting member 10.

[0017] The reduction gear 11 is a device that reduces the rotation speed of the output shaft 4 of the motor 3 and transmits it to the drive shaft 14. The reduction gear 11 is disposed below the motor 3. The reduction gear 11 includes a drive gear 12 and a driven gear 13. The drive gear 12 is connected to the 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. The driven gear 13 is also connected to the upper end of the drive shaft 14. The driven gear 13 is also in mesh with the drive gear 12. The gear ratio between the drive gear 12 and the driven gear 13 (the number of teeth of the driven gear 13 / the number of teeth of the drive gear 12) is greater than 1.

[0018] The drive shaft 14 is a shaft that transmits the rotation of the motor 3 after being reduced in speed by the reduction gear 11 to the propeller shaft 18. The drive shaft 14 extends in the vertical direction from the reduction gear 11 to the rotation transmission mechanism 15. As described above, the driven gear 13 of the reduction gear 11 is coupled to the upper end of the drive shaft 14, and the drive shaft 14 rotates integrally with the driven gear 13.

[0019] The rotation transmission mechanism 15 is a mechanism that transmits the rotation of the drive shaft 14 to the propeller shaft 18. The rotation transmission mechanism 15 includes two bevel gears 16 and 17 that mesh with each other. One of the bevel gears, 16, is coupled to the lower end of the drive shaft 14 and rotates integrally with the drive shaft 14. The other bevel gear, 17, is coupled to the front end of the propeller shaft 18.

[0020] The propeller shaft 18 extends in the front-to-rear direction and is disposed below the motor 3. As described above, the bevel gear 17 of the rotation transmission mechanism 15 is coupled to the front end of the propeller shaft 18, and the propeller shaft 18 rotates integrally with the bevel gear 17. The propeller 21 is coupled to the rear end of the propeller shaft 18 and rotates integrally with the propeller shaft 18. The propeller shaft 18 and the propeller 21 are disposed below the electric propulsion unit 1, and are located below the water surface when the electric propulsion unit 1 is attached to the vessel.

[0021] The motor 3 is driven under the control of the inverter 6, causing the output shaft 4 to rotate. The rotation of the output shaft 4 is transmitted to the drive shaft 14 while being reduced in speed by the reduction gear 11, causing the drive shaft 14 to rotate. The rotation of the drive shaft 14 is transmitted to the propeller shaft 18 by the rotation transmission mechanism 15, causing the propeller shaft 18 and the propeller 21 to rotate. The rotation of the propeller 21 generates propulsion force for the vessel.

[0022] Additionally, in the electric propulsion device 1, a middle case 25 is provided below the motor 3. The middle case 25 is connected to the motor case 5 using connecting members such as bolts. The middle case 25 houses the reduction gear 11, the upper part of the drive shaft 14, and the like.

[0023] Additionally, in the electric propulsion unit 1, a lower case 27 is provided below the middle case 25. The lower case 27 is connected to the middle case 25 using connecting members such as bolts. The lower case 27 houses the lower part of the drive shaft 14, the rotation transmission mechanism 15, the front part of the propeller shaft 18, and the like.

[0024] Specifically, a drive shaft insertion hole 28 extending in the up-down direction is provided in the front portion of the lower case 27, and the lower portion of the drive shaft 14 is inserted into the drive shaft insertion hole 28. A transmission mechanism accommodating chamber 29 is provided in the lower front portion of the lower case 27, and the rotation transmission mechanism 15 is accommodated in the transmission mechanism accommodating chamber 29. A propeller shaft accommodating hole 30 is provided in the lower portion of the lower case 27, rearward of the transmission mechanism accommodating chamber 29. The propeller shaft accommodating hole 30 extends in the front-rear direction. The front end of the propeller shaft accommodating hole 30 communicates with the interior of the transmission mechanism accommodating chamber 29, and the rear end of the propeller shaft accommodating hole 30 communicates with the interior of the hub 22 of the propeller 21.

[0025] A shaft housing 31 is provided and fixed in the propeller shaft accommodating hole 30. The shaft housing 31 is a cylindrical member that rotatably supports the propeller shaft 18 relative to the lower case 27 via a bearing 20. The front portion of the propeller shaft 18 is disposed inside the shaft housing 31 and is rotatably supported within the shaft housing 31 via the bearing 20.

[0026] An anti-cavitation plate 35 is provided above the propeller 21 in the lower case 27. A skeg 36 is provided at the bottom of the lower case 27.

[0027] 1, the electric propulsion unit 1 is equipped with an attachment mechanism 40 that attaches the electric propulsion unit 1 to the vessel. The attachment mechanism 40 includes a clamp bracket 41 that secures the electric propulsion unit 1 to the transom of the vessel, a swivel bracket 43 that is connected to the clamp bracket 41 via a tilt shaft 42, a pilot shaft 44 that extends in the vertical direction and is rotatably supported by the swivel bracket 43, and mounts 45, 46 that connect the upper and lower ends of the pilot shaft 44 to the electric propulsion unit 1.

[0028] (cooling device) 4 shows the configuration of the cooling device 51 in the electric propulsion unit 1. The cooling device 51 is a liquid-cooled cooling device that cools the equipment that needs to be cooled, that is, the equipment that needs to be cooled, that is provided in the electric propulsion unit 1. The equipment that needs to be cooled that is provided in the electric propulsion unit 1 is the motor 3, the inverter 6, and the reduction gear 11.

[0029] As shown in Fig. 4, the cooling device 51 includes a direct cooling system 52 and an indirect cooling system 71. The direct cooling system 52 is a system that cools the refrigerant used in the indirect cooling system 71 by performing heat exchange between water (e.g., seawater) outside the electric propulsion device 1 and the refrigerant used in the indirect cooling system 71. The indirect cooling system 71 is a system that cools the equipment that needs to be cooled by performing heat exchange between the refrigerant cooled in the direct cooling system and the equipment that needs to be cooled. The refrigerant is, for example, a coolant such as LLC.

[0030] (Direct cooling system) As shown in FIG. 4, the direct cooling system 52 includes a water intake 53, a water intake passage 54, a heat exchanger 55, and a water outlet 70.

[0031] The water intake 53 is an opening through which water from outside the electric propulsion unit 1 is taken into the electric propulsion unit 1 as cooling water. Here, Fig. 5 shows the lower part of the lower case 27 of the electric propulsion unit 1 as seen from the front. As shown in Figs. 3 and 5, the water intake 53 is provided in front of the part where the lower case 27 and the skeg 36 are joined together, that is, at the base end of the front part of the skeg 36. The water intake 53 opens forward.

[0032] The water intake passage 54 is a passage that connects the water intake 53 and the cooling water inlet chamber 61 of the heat exchanger 55, and is a passage that sends water from outside the electric propulsion device 1 that has flowed into the water intake 53, i.e., the cooling water, to the cooling water inlet chamber 61 of the heat exchanger 55. As shown in FIG. 3 , the water intake passage 54 extends in the front-to-rear direction between the lower case 27 and the skeg 36.

[0033] The heat exchanger 55 is a device that uses water outside the electric propulsion unit 1 as cooling water to cool the refrigerant in the indirect cooling system 71. As shown in FIG. 3 , the heat exchanger 55 is provided inside the lower case 27. The heat exchanger 55 is provided inside the lower case 27 on the outer periphery of the propeller shaft 18. Specifically, the heat exchanger 55 is formed on the outer periphery of the shaft housing 31 that is provided inside the propeller shaft accommodating hole 30. Furthermore, when the electric propulsion unit 1 is viewed from above, the heat exchanger 55 is positioned so as to overlap with the motor 3.

[0034] Here, FIG. 6 shows a longitudinal cross section of the heat exchanger 55. FIG. 7(A) shows the heat exchanger 55 in FIG. 6 as seen from the front. FIG. 7(B) shows a cross section of the heat exchanger 55 cut along section line BB in FIG. 6 as seen from the front (left in FIG. 6). FIG. 7(C) shows a cross section of the heat exchanger 55 cut along section line CC in FIG. 6 as seen from the front. FIG. 7(D) shows a cross section of the heat exchanger 55 cut along section line DD in FIG. 6 as seen from the front. FIG. 7(E) shows the heat exchanger 55 in FIG. 6 as seen from the rear. FIG. 8 shows an enlarged view of a portion of the electric propulsion device 1 in FIG. 3 where the heat exchanger 55 is provided.

[0035] 6, the heat exchanger 55 includes a foremost partition wall portion 56, a front partition wall portion 57, a rear partition wall portion 58, a cooling water inlet chamber 61, a refrigerant flow chamber 62, a cooling water outlet chamber 63, a cooling water passage 64 (a plurality of cooling pipes 65), a refrigerant passage 67, and a baffle plate 68. Furthermore, the heat exchanger 55 includes an axial flow impeller 69, as shown in FIG.

[0036] As shown in Fig. 6, the shaft housing 31 basically comprises a cylindrical shaft housing main body 32 and an annular fixing portion 33 that protrudes radially outward from the rear end of the shaft housing main body 32. As shown in Fig. 8, the shaft housing 31 is attached to the lower case 27 by inserting the shaft housing main body 32 into the propeller shaft accommodating hole 30 from the rear and fixing the fixing portion 33 to a part of the lower case 27 (the peripheral edge of the opening of the propeller shaft accommodating hole 30) using a connecting member such as a bolt.

[0037] As shown in Fig. 6, the foremost partition wall 56, the front partition wall 57, and the rear partition wall 58 of the heat exchanger 55 are formed in the shaft housing 31. The foremost partition wall 56, the front partition wall 57, and the rear partition wall 58 function to form a coolant inlet chamber 61, a refrigerant flow chamber 62, and a coolant outlet chamber 63 on the outer circumferential side of the propeller shaft 18 within the propeller shaft accommodating hole 30. As shown in Fig. 8, these three partition wall portions 56, 57, and 58 divide the space between the propeller shaft accommodating hole 30 and the propeller shaft 18, specifically the space between the propeller shaft accommodating hole 30 and the shaft housing main body 32, into the coolant inlet chamber 61, the refrigerant flow chamber 62, and the coolant outlet chamber 63.

[0038] As shown in FIGS. 6 and 7(A), the foremost end partition wall 56 projects radially outward from the front end of the shaft housing main body 32 and is formed around the entire periphery of the shaft housing main body 32.

[0039] 6 and 7(B), the front partition wall 57 is located rearward of the foremost partition wall 56. The front partition wall 57 protrudes radially outward from the front of the shaft housing main body 32 and is formed around the entire circumference of the shaft housing main body 32.

[0040] 6 and 7(E), the rear partition wall 58 is located rearward of the front partition wall 57. The rear partition wall 58 protrudes radially outward from the rear of the shaft housing main body 32 and is formed around the entire circumference of the shaft housing main body 32.

[0041] 8, when the shaft housing 31 is placed in the propeller shaft accommodating hole 30, the space between the propeller shaft accommodating hole 30 and the shaft housing main body 32 is divided into a cooling water inlet chamber 61 located in the front part of the space, a refrigerant flow chamber 62 located in the middle part of the space in the front-rear direction, and a cooling water outlet chamber 63 located in the rear part of the space. The cooling water inlet chamber 61, the refrigerant flow chamber 62, and the cooling water outlet chamber 63 are each annular spaces that completely surround the outer periphery of the shaft housing main body 32.

[0042] The cooling water passage 64 is a passage within the heat exchanger 55 through which cooling water flows. As shown in FIGS. 6, 7(B) to 7(E), and 8, the cooling water passage 64 is formed by a plurality of cooling pipes 65 provided between the propeller shaft accommodating hole 30 and the shaft housing main body 32. Each cooling pipe 65 is a pipe made of a metal with high thermal conductivity, such as copper. Each cooling pipe 65 extends in the axial direction of the propeller shaft 18. The front end of each cooling pipe 65 is supported by the front bulkhead portion 57, and the rear end of each cooling pipe 65 is supported by the rear bulkhead portion 58. The inlet end (front end) of each cooling pipe 65 opens into the cooling water inlet chamber 61, and the interior of each cooling pipe 65 communicates with the interior of the cooling water inlet chamber 61. The outlet end (rear end) of each cooling pipe 65 opens into the cooling water outlet chamber 63, and the interior of each cooling pipe 65 communicates with the interior of the cooling water outlet chamber 63. In this way, the cooling water inlet chamber 61 and the cooling water outlet chamber 63 are in communication with each other via the cooling pipes 65. Each cooling pipe 65 also passes through the refrigerant flow chamber 62. As will be described later, a refrigerant flows within the refrigerant flow chamber 62, and each cooling pipe 65 is arranged to pass through the refrigerant. Although each cooling pipe 65 passes through the refrigerant flow chamber 62, the interior of each cooling pipe 65 does not communicate with the interior of the refrigerant flow chamber 62. In this embodiment, twelve cooling pipes 65 are arranged around the entire outer periphery of the shaft housing 31 at intervals of 30 degrees.

[0043] 8, the lower part of the cooling water inlet chamber 61 communicates with the water intake passage 54. The rear part of the cooling water outlet chamber 63 opens widely rearward and communicates with the inside of the hub 22 of the propeller 21.

[0044] The refrigerant passage 67 is a passage within the heat exchanger 55 through which the refrigerant used in the indirect cooling system 71 flows. The refrigerant passage 67 is formed within the refrigerant flow chamber 62. As shown in FIG. 3 , a circulation passage that circulates the refrigerant in the indirect cooling system 71 is connected to the refrigerant flow chamber 62. Specifically, the lower end of a hole 86B of a connecting passage 86 that constitutes part of the circulation passage opens to the inner surface of the upper part of the propeller shaft accommodation hole 30. The opening of the lower end of the hole 86B of the connecting passage 86 is located above the front part of the refrigerant flow chamber 62. Therefore, the hole 86B of the connecting passage 86 communicates with the front part of the refrigerant flow chamber 62. Furthermore, the lower end of a hole 81A of a connecting passage 81 that constitutes part of the circulation passage opens to the inner surface of the upper part of the propeller shaft accommodation hole 30. The opening of the lower end of the hole 81A of the connecting passage 81 is located above the rear part of the refrigerant flow chamber 62. Therefore, hole 81A of connecting passage 81 communicates with the rear portion of refrigerant flow chamber 62. As shown in Figure 8, the inflow end of refrigerant passage 67 is connected to the opening at the lower end of hole 86B of connecting passage 86, and the outflow end of refrigerant passage 67 is connected to the opening at the lower end of hole 81A of connecting passage 81.

[0045] As shown in FIG. 6, a plurality of baffle plates 68 are provided on the outer periphery of the shaft housing main body 32. As shown in FIG. 7(C) or 7(D), each baffle plate 68 is a circular plate with a central hole. The shaft housing main body 32 is inserted into the central hole of each baffle plate 68. A notch 68A is formed by cutting out a portion of the baffle plate 68 on a portion of the outer periphery of the baffle plate 68. As shown in FIG. 6, the baffle plates 68 are arranged at intervals in the front-to-rear direction on the outer periphery of the shaft housing main body 32 in a portion corresponding to the refrigerant flow chamber 62. The baffle plates 68 are arranged such that the positions of their respective notches 68A are staggered in the up-down direction. In FIG. 6, of the three baffle plates 68, the front baffle plate 68 and the rear baffle plate 68 are arranged such that the notches 68A are positioned downward, and the middle baffle plate 68 is arranged such that the notch 68A is positioned upward. The multiple baffle plates 68 divide the refrigerant flow chamber 62 into multiple annular spaces, as if slicing it into slices. However, because each baffle plate 68 has a cutout 68A, portions of two adjacent annular spaces communicate with each other via the cutout 68A. In this way, the multiple baffle plates 68 form a refrigerant passage 67 within the refrigerant flow chamber 62 that extends in the circumferential direction of the propeller shaft 18. The multiple baffle plates 68 are arranged so that the positions of their respective cutouts 68A are staggered in the vertical direction, so when the electric propulsion unit 1 is viewed from the side, the shape of the refrigerant passage 67 is zigzag in the vertical direction (a shape that folds back in the vertical direction).

[0046] As shown in Fig. 8, the axial flow impeller 69 is disposed in the cooling water outflow chamber 63. The axial flow impeller 69 is located in front of the hub 22 of the propeller 21. The axial flow impeller 69 is coupled to the propeller shaft 18 and rotates integrally with the propeller shaft 18. The axial flow impeller 69 has the function of sending the cooling water that has flowed out from the cooling water passage 64 (each cooling pipe 65) into the cooling water outflow chamber 63 to the inside of the hub 22 of the propeller 21.

[0047] The drain port 70 is an opening for discharging the cooling water, which has flowed through the cooling water passage 64 of the heat exchanger 55, to the outside of the electric propulsion device 1. As shown in Figures 2 and 3, the drain port 70 is formed inside the hub 22 of the propeller 21.

[0048] The cooling operation of the refrigerant in the direct cooling system 52 will be described with reference to Fig. 8. In Fig. 8, the open arrows indicate the flow of the cooling water, and the solid arrows indicate the flow of the refrigerant.

[0049] In FIG. 8 , the motor 3 of the electric propulsion unit 1 is driven to rotate the propeller 21, moving the boat forward. When the boat is moving forward, water in front of the electric propulsion unit 1 hits the front portion of the lower part of the lower case 27. As a result, water outside the electric propulsion unit 1 flows from the water intake port 53 into the water intake passage 54 as cooling water. The cooling water that flows into the water intake passage 54 flows rearward through the water intake passage 54 and into the cooling water inlet chamber 61 of the heat exchanger 55. Within the heat exchanger 55, the cooling water that flows into the cooling water inlet chamber 61 flows into the cooling water passage 64, i.e., into the multiple cooling pipes 65. The cooling water then flows through each cooling pipe 65 in the axial direction of the propeller shaft 18 and flows out into the cooling water outlet chamber 63. The cooling water that flows out into the cooling water outlet chamber 63 is sent by the axial impeller 69 to the inside of the hub 22 of the propeller 21 and is discharged outside the electric propulsion unit 1 through the outlet port 70.

[0050] In the indirect cooling system 71, the refrigerant pump 75 is driven to cause the refrigerant to flow through the circulation passage. The refrigerant flowing through the circulation passage flows through a hole 86B of a connecting passage 86 that constitutes part of the circulation passage, and then flows into the front side of the refrigerant flow chamber 62 of the heat exchanger 55, i.e., into the inlet end of the refrigerant passage 67. The refrigerant that has flowed into the inlet end of the refrigerant passage 67 flows through the refrigerant passage 67 in the circumferential direction of the propeller shaft 18 and in a zigzag pattern in the up-and-down direction. After flowing through the refrigerant passage 67, the refrigerant flows out from the rear side of the refrigerant flow chamber 62, i.e., the outlet end of the refrigerant passage 67, into a hole 81A of a connecting passage 81 that constitutes part of the circulation passage.

[0051] In this way, in the heat exchanger 55, the cooling water flows through the cooling water passage 64 (in each cooling pipe 65), and at the same time, the refrigerant flows through the refrigerant passage 67, so that heat is exchanged between the cooling water and the refrigerant, and the refrigerant is cooled by the cooling water.

[0052] (Indirect cooling system) 4, the indirect cooling system 71 includes a motor cooling jacket 72, an inverter cooling jacket 73, a reduction gear cooling jacket 74, a refrigerant pump 75, a degassing tank 76, and a circulation passage. The circulation passage has connecting passages 81-86.

[0053] The motor cooling jacket 72 is a mechanism that uses a refrigerant to cool the motor 3. As shown in FIG. 3, the motor cooling jacket 72 is provided on the motor 3. For example, the motor cooling jacket 72 is composed of flow paths formed in the motor case 5 of the motor 3. The flow paths that make up the motor cooling jacket 72 are formed over a wide area of ​​the motor case 5. For example, the flow paths are formed around the entire circumference of the motor case 5, and are formed from one end portion of the motor case 5 to the other end portion in the axial direction.

[0054] The inverter cooling jacket 73 is a mechanism that uses a refrigerant to cool the inverter 6. As shown in FIG. 3 , the inverter cooling jacket 73 is provided on the inverter 6. For example, the inverter cooling jacket 73 is disposed in the lower rear part of the inverter 6, and is located below the rear part of the inverter main body 7. Specifically, the inverter cooling jacket 73 is configured by a flow path formed in the lower rear part of the inverter case 8. The flow path extends from the left end to the right end of the inverter case 8.

[0055] The reduction gear cooling jacket 74 is a mechanism that uses cooling water to cool the reduction gear 11. The reduction gear cooling jacket 74 is configured with a cooling water flow path that passes through a location adjacent to the reduction gear 11. The reduction gear cooling jacket 74 is disposed below the reduction gear 11 inside the middle case 25.

[0056] Refrigerant pump 75 is a pump that circulates the refrigerant within the circulation passage. Refrigerant pump 75 is an electric pump, and is driven, for example, by a dedicated motor for refrigerant pump 75 that is separate from motor 3. As shown in FIG. 1 , refrigerant pump 75 is disposed above heat exchanger 55. Refrigerant pump 75 is also disposed behind inverter 6. Refrigerant pump 75 is also attached to the rear of inverter 6. Refrigerant pump 75 can adjust the flow rate of the refrigerant within the circulation passage by, for example, changing the rotation speed of the dedicated motor for refrigerant pump 75. This allows for temperature control of the refrigerant.

[0057] The degassing tank 76 is a tank that separates gas from the refrigerant. Specifically, the degassing tank 76 has the function of releasing bubbles that have been generated in the refrigerant due to heat or the like, and the function of acting as a reserve tank to absorb any increase or decrease in the amount of refrigerant due to thermal expansion or aging of the refrigerant. The degassing tank 76 is disposed above the inverter 6 and attached to the inverter 6.

[0058] The circulation passage is a passage that circulates the refrigerant between the heat exchanger 55 and the motor cooling jacket 72, the inverter cooling jacket 73, and the reduction gear cooling jacket 74. As shown in Fig. 4, in the indirect cooling system 71 of this embodiment, the heat exchanger 55, the motor cooling jacket 72, the inverter cooling jacket 73, the refrigerant pump 75, and the reduction gear cooling jacket 74 are connected in series in this order via the circulation passage. The circulation passage has a connecting passage 81 connecting the heat exchanger 55 and the motor cooling jacket 72, a connecting passage 82 connecting the motor cooling jacket 72 and the inverter cooling jacket 73, a connecting passage 83 connecting the inverter cooling jacket 73 and the passage joint 88, a connecting passage 84 connecting the passage joint 88 and the refrigerant pump 75, a connecting passage 85 connecting the refrigerant pump 75 and the reduction gear cooling jacket 74, a connecting passage 86 connecting the reduction gear cooling jacket 74 and the heat exchanger 55, and a connecting passage 87 connecting the passage joint 88 and the degassing tank 76.

[0059] As shown in FIGS. 3 and 8 , the inlet end of the connecting passage 81 is connected to the outlet end of the refrigerant passage 67 of the heat exchanger 55, and the outlet end of the connecting passage 81 is connected to the inlet 72A of the motor cooling jacket 72. The connecting passage 81 is formed by, for example, connecting a hole 81A, an internal pipe 81B, and an external pipe 81C in this order from the inlet end to the outlet end. The hole 81A is formed in the lower case 27. The internal pipe 81B is formed, for example, by a pipe or a hose, and extends generally vertically from inside the lower case 27 to inside the middle case 25. The external pipe 81C is formed, for example, by a pipe or a hose, and extends generally vertically outside the middle case 25 to the left of the middle case 25, as shown in FIG. 2 . In addition, as shown in Figures 1 and 3, a connection port 89 is formed in the left wall of the middle case 25 to connect the inside and outside of the middle case 25, and the outlet end of the inner pipe portion 81B and the inlet end of the outer pipe portion 81C are connected to each other via the connection port 89.

[0060] The connecting passage 82 is provided in the section extending from the upper left rear of the motor case 5 to the lower left rear of the inverter case 8. The connecting passage 82 is formed by a hole provided inside this section and extending in the vertical direction. The inlet end of the connecting passage 82 is connected to the outlet of the motor cooling jacket 72 provided in the upper left rear of the motor case 5, and the outlet end of the connecting passage 82 is connected to the inlet of the inverter cooling jacket 73 provided in the lower left rear of the inverter case 8.

[0061] As shown in FIG. 2 , the connection passage 83 is disposed to the rear right of the inverter 6. The connection passage 83 is formed, for example, by a hose or a pipe. The inlet end of the connection passage 83 is connected to an outlet of the inverter cooling jacket 73, which opens into the right surface of the lower rear part of the inverter case 8. The outlet end of the connection passage 83 is connected to a passage joint 88. The passage joint 88 is a portion that connects the outlet end of the connection passage 83, the inlet end of the connection passage 84, and the lower end of the connection passage 87 to each other, and is formed, for example, by a T-joint.

[0062] The connection passage 84 is disposed to the right of the refrigerant pump 75. The connection passage 84 is formed, for example, by a pipe. An inflow end of the connection passage 84 is connected to the passage joint 88. An outflow end of the connection passage 84 is connected to a suction port of the refrigerant pump 75 provided on the right surface of the refrigerant pump 75.

[0063] The connecting passage 85 is located outside the motor 3 and the middle case 25, extending from the rear of the motor 3 to the rear of the middle case 25, and extends in the vertical direction. The connecting passage 85 is formed, for example, by a pipe or a hose. The inlet end of the connecting passage 85 is connected to the discharge port of the refrigerant pump 75, which is provided at the lower right of the refrigerant pump 75. As shown in FIG. 3 , the rear of the middle case 25 is provided with an inlet 74A of the reduction gear cooling jacket 74, which communicates with the interior of the reduction gear cooling jacket 74 and opens to the rear face of the middle case 25. The outlet end of the connecting passage 85 is connected to this inlet 74A.

[0064] 3 and 8 , the inlet end of the connecting passage 86 is connected to the outlet 74B of the reduction gear cooling jacket 74, and the outlet end of the connecting passage 86 is connected to the inlet end of the refrigerant passage 67 in the heat exchanger 55. The connecting passage 86 is formed, for example, by connecting an internal pipe portion 86A and a hole portion 86B in this order from the inlet end to the outlet end. The internal pipe portion 86A is formed, for example, by a pipe or a hose, and extends generally in the vertical direction from inside the middle case 25 to inside the lower case 27. The hole portion 86B is formed in the lower case 27.

[0065] The connecting passage 87 is disposed above the right rear portion of the inverter 6 and behind the right portion of the degassing tank 76. The connecting passage 87 is formed, for example, by a hose or a pipe. The lower end of the connecting passage 87 is connected to a passage joint 88. The upper end of the connecting passage 87 is connected to the right rear portion of the degassing tank 76.

[0066] When the refrigerant pump 75 is driven, the refrigerant cooled by the heat exchanger 55 flows out from the outlet end of the refrigerant passage 67 of the heat exchanger 55, flows through the connecting passage 81, and then flows through the motor cooling jacket 72. The refrigerant flows through the motor cooling jacket 72, thereby cooling the motor 3. After flowing through the motor cooling jacket 72, the refrigerant flows through the connecting passage 82 and then through the inverter cooling jacket 73. The refrigerant flows through the inverter cooling jacket 73, thereby cooling the inverter main body 7. After flowing through the inverter cooling jacket 73, the refrigerant flows sequentially through the connecting passage 83, the passage joint 88, the connecting passage 84, the refrigerant pump 75, and the connecting passage 85, before flowing into and flowing through the reduction gear cooling jacket 74. The refrigerant flows through the reduction gear cooling jacket 74, thereby cooling the reduction gear 11. After flowing through the reduction gear cooling jacket 74, the refrigerant flows through the connecting passage 86 and flows into the refrigerant passage 67 from the inlet end of the refrigerant passage 67 of the heat exchanger 55. The refrigerant, whose temperature has risen due to heat from the motor 3, the inverter 6, and the reduction gear 11, is cooled in the heat exchanger 55 by cooling water taken in from outside the electric propulsion machine 1.

[0067] A refrigerant is stored in the degassing tank 76. Air bubbles in the refrigerant move into the degassing tank 76 through the connecting passage 87 and are released into the atmosphere, for example, through a gas vent passage formed in the degassing tank 76. When the amount of refrigerant flowing through the circulation passage becomes low, the cap of the degassing tank 76 can be removed and refrigerant can be injected into the degassing tank 76 to replenish the refrigerant.

[0068] As described above, in the cooling device 51 provided in the electric propulsion 1 of this embodiment, the heat exchanger 55 cools the coolant using water (e.g., seawater) outside the electric propulsion 1. The motor cooling jacket 72, the inverter cooling jacket 73, and the reduction gear cooling jacket 74 are cooled by the heat exchangers, and the motor 3, the inverter 6, and the reduction gear 11 are cooled using the coolant circulating in the circulation passage. Because the motor cooling jacket 72 cools the motor 3 using the coolant circulating in the circulation passage, water outside the electric propulsion 1 does not flow through the motor cooling jacket 72. In other words, seawater does not flow through the motor cooling jacket 72. Therefore, with the electric propulsion 1 of this embodiment, the motor cooling jacket 72 can be prevented from being corroded by seawater. Similarly, because seawater does not flow through the inverter cooling jacket 73, the inverter cooling jacket 73 can be prevented from being corroded by seawater. Similarly, because seawater does not flow through the reduction gear cooling jacket 74, the reduction gear cooling jacket 74 can be prevented from being corroded by seawater. Therefore, according to the electric propulsion device 1 of this embodiment, corrosion of the motor cooling jacket 72, the inverter cooling jacket 73, and the reduction gear cooling jacket 74 can be suppressed.

[0069] Furthermore, in the electric propulsion unit 1 of this embodiment, the heat exchanger 55 is provided inside the lower case 27. Heat exchangers are generally heavy, and if the heat exchanger were provided on top of the electric propulsion unit, the center of gravity of the electric propulsion unit would be higher, which could reduce the stability of the electric propulsion unit when it is installed on a boat. With the electric propulsion unit 1 of this embodiment, the heat exchanger 55 is provided inside the lower case 27, so the heat exchanger 55 can be located below the electric propulsion unit 1. This allows the center of gravity of the electric propulsion unit 1 to be lowered, improving the stability of the electric propulsion unit when installed on a boat.

[0070] Furthermore, in the electric propulsion unit 1 of this embodiment, the heat exchanger 55 is provided inside the lower case 27, on the outer periphery side of the propeller shaft 18. With this configuration, the heat exchanger 55 is located in the lower part of the lower case 27, which makes it possible to lower the center of gravity of the electric propulsion unit 1. Furthermore, because the lower part of the lower case 27 is completely submerged in water, the water surrounding the lower case 27 can lower the temperature of the heat exchanger 55, thereby increasing the cooling capacity of the heat exchanger 55 for the refrigerant.

[0071] Furthermore, in the electric propulsion 1 of this embodiment, the heat exchanger 55 includes a coolant passage 64 through which coolant flows in the axial direction of the propeller shaft 18, and a refrigerant passage 67 through which refrigerant flows in the circumferential direction of the propeller shaft 18. With this configuration, the coolant passage 64 can be made shorter than the refrigerant passage 67. This allows the coolant to be replaced more quickly. Furthermore, the refrigerant passage 67 can be made longer than the coolant passage 64. This allows the time from when the refrigerant flows into the heat exchanger 55 to when it flows out of the heat exchanger 55 to be longer, and the time over which the refrigerant is cooled by the heat exchanger 55 to be longer. Overall, the refrigerant cooling capacity of the heat exchanger 55 can be increased.

[0072] Furthermore, in the heat exchanger 55 according to this embodiment, the cooling water passage 64 has a plurality of cooling pipes 65 through which cooling water flows, and each cooling pipe 65 is arranged to pass through the refrigerant flowing in the refrigerant passage 67. In this configuration, the refrigerant comes into contact with the outer circumferential surface of each cooling pipe 65, thereby exchanging heat between the cooling water and the refrigerant. By providing a plurality of cooling pipes 65, the area over which the refrigerant comes into contact with the cooling pipes 65 can be increased when the plurality of cooling pipes 65 are viewed as a whole. This increases the cooling capacity of the heat exchanger 55 for the refrigerant.

[0073] Furthermore, in the electric propulsion device 1 of this embodiment, a propeller shaft accommodating hole 30 is provided in the lower part of the lower case 27, a shaft housing 31 is provided inside the propeller shaft accommodating hole 30, and a coolant passage 64 and a refrigerant passage 67 of the heat exchanger 55 are provided between the propeller shaft accommodating hole 30 and the shaft housing main body 32. With this configuration, the space inside the propeller shaft accommodating hole 30 can be partitioned into an inner space through which oil flows to lubricate the bearings 20 and the like, and an outer space in which the coolant passage 64 and the refrigerant passage 67 of the heat exchanger 55 are provided, and the coolant passage 64 and the refrigerant passage 67 can be easily provided on the outer periphery of the propeller shaft 18.

[0074] Furthermore, in the electric propulsion 1 of this embodiment, the space between the propeller shaft accommodating hole 30 and the propeller shaft 18 is divided by the shaft housing 31 into a coolant inlet chamber 61, a refrigerant flow chamber 62, and a coolant outlet chamber 63, the refrigerant passage 67 is formed in the refrigerant flow chamber 62, the inlet end of the coolant passage 64 communicates with the coolant inlet chamber 61, the outlet end of the coolant passage 64 communicates with the coolant outlet chamber 63, and the coolant passage 64 passes through the refrigerant flow chamber 62 without communicating with the refrigerant flow chamber 62. This configuration makes it possible to achieve, with a simple structure, an arrangement of the coolant passage 64 and the refrigerant passage 67 that allows for efficient heat exchange between the coolant and the refrigerant.

[0075] Furthermore, in the electric propulsion unit 1 of this embodiment, the water intake 53 that takes in water outside the electric propulsion unit 1 into the electric propulsion unit 1 is provided in the front part of the part where the lower case 27 and the skeg 36 are joined together. This configuration makes it possible to increase the amount of cooling water taken in while reducing resistance when the vessel is moving. Furthermore, in the electric propulsion unit 1 of this embodiment, the water intake passage 54 that connects the water intake 53 and the cooling water inlet chamber 61 extends in the fore-and-aft direction between the lower case 27 and the skeg 36. This configuration makes it possible to shorten the water intake passage 54, allowing cooling water to be smoothly sent from the water intake 53 to the cooling water inlet chamber 61.

[0076] Furthermore, in the electric propulsion 1 of this embodiment, the cooling device 51 includes an axial impeller 69 that rotates integrally with the propeller shaft 18, the cooling water outflow chamber 63 communicates with the inside of the hub of the propeller 21, and the axial impeller 69 is disposed within the cooling water outflow chamber 63. With this configuration, the rotation of the propeller shaft 18 can be used to smoothly discharge the cooling water that has flowed through the cooling water passage 64 to the outside of the electric propulsion 1. Furthermore, because the axial impeller 69 rotates due to the rotation of the propeller shaft 18, there is no need to provide a separate electric motor or the like for rotating the axial impeller 69, which simplifies the structure of the electric propulsion 1 and reduces the manufacturing costs of the electric propulsion 1.

[0077] Furthermore, in the heat exchanger 55 according to this embodiment, a baffle plate 68 is provided in the refrigerant flow chamber 62 to cause the refrigerant to flow in a zigzag pattern within the refrigerant flow chamber 62. This configuration allows the refrigerant passage 67 formed within the refrigerant flow chamber 62 to be longer, thereby lengthening the cooling time of the refrigerant and increasing the cooling capacity of the heat exchanger 55.

[0078] Furthermore, in this embodiment, the heat exchanger 55 is disposed so as to overlap the motor 3 when the electric propulsion device 1 is viewed from above. This configuration allows the connecting passages 81 and 86 to be shortened, and the flow of refrigerant in the circulation passages to be smoother. [Example]

[0079] Fig. 9 shows the configuration of a cooling device 91 in an electric propulsion device 90 according to a second embodiment of the present invention. Fig. 10 shows the arrangement of two heat exchangers 95, 98 provided in the cooling device 91 in an electric propulsion device 90 according to the second embodiment of the present invention.

[0080] An electric propulsion device 90 according to the second embodiment of the present invention is characterized in that a direct cooling system 92 of a cooling device 91 provided in the electric propulsion device 90 includes two heat exchangers 95 and 98 .

[0081] Specifically, as shown in FIG. 9 , the direct cooling system 92 of the cooling device 91 includes a first water intake 93, a first water intake passage 94, a first heat exchanger 95, a second water intake 96, a second water intake passage 97, a second heat exchanger 98, a discharge passage 99 for the second heat exchanger 98, and a drain outlet 100.

[0082] The first water intake 93 is an inlet for taking water from outside the electric propulsion unit 90 into the electric propulsion unit 90 as cooling water for the first heat exchanger 95. The first water intake passage 94 is a passage for sending the cooling water to the first heat exchanger 95. The first heat exchanger 95 is a device that uses the cooling water to cool the refrigerant in the indirect cooling system 71. The first water intake 93, the first water intake passage 94, and the first heat exchanger 95 are the same as the water intake 53, the water intake passage 54, and the heat exchanger 55 in the cooling device 51 according to the first embodiment of the present invention. That is, as shown in FIG. 10 , the first water intake 93 opens in the front portion of the portion where the lower case 27 and the skeg 36 are joined to each other. The first water intake passage 94 extends in the front-to-rear direction between the lower case 27 and the skeg. The first heat exchanger 95 is provided inside the lower case 27 on the outer circumferential side of the propeller shaft 18 .

[0083] The second water intake 96 is an inlet that takes in water outside the electric propulsion unit 90 into the electric propulsion unit 90 as cooling water for the second heat exchanger 98. The second water intake 96 opens at the front of the side surface of the lower case 27, below the anti-cavitation plate 35 and above the propeller shaft 18. The second water intake 96 is positioned so that it is submerged in water. The second water intake passage 97 is a passage that sends the cooling water that has been taken into the electric propulsion unit 90 from the second water intake 96 to the second heat exchanger 98. The second water intake passage 97 is provided inside the lower case 27.

[0084] The second heat exchanger 98 is a device that cools the refrigerant in the indirect cooling system 71 using cooling water supplied via the second water intake passage 97. The second heat exchanger 98 is provided above the propeller shaft 18 inside the lower case 27. The second heat exchanger 98 is preferably positioned so as to overlap the anti-cavitation plate 35 when the electric propulsion unit 90 is viewed from the rear. As shown in FIG. 9 , the second heat exchanger 98 is connected midway through the connecting passage 86 that constitutes part of the circulation passage of the indirect cooling system 71, and midway through the connecting passage 81 that constitutes part of the circulation passage of the indirect cooling system 71. The second heat exchanger 98 uses cooling water supplied via the second water intake passage 97 to cool the refrigerant flowing in the connecting passage 86 and the refrigerant flowing in the connecting passage 81.

[0085] The discharge passage 99 is a passage that carries the cooling water that has flowed through the second heat exchanger 98 to a drain port 100. The discharge passage 99 is provided in the lower case 27.

[0086] The water outlet 100 is an opening for discharging the cooling water after flowing through the first heat exchanger 95 and the cooling water after flowing through the second heat exchanger 98 to the outside of the electric propulsion device 90. The water outlet 100 is formed inside the hub of the propeller 21, similar to the water outlet 70 according to the first embodiment.

[0087] When the boat is moving forward, water in front of the electric propulsion unit 90 hits the front part of the lower part of the lower case 27. As a result, water outside the electric propulsion unit 90 is sent as cooling water to the first heat exchanger 95 via the first water intake 93 and the first water intake passage 94, and the first heat exchanger 95 cools the refrigerant in the indirect cooling system 71. Furthermore, when the boat is moving forward, water in front of the electric propulsion unit 90 hits the lower part of the lower case 27, and water outside the electric propulsion unit 90 is sent as cooling water to the second heat exchanger 98 via the second water intake 96 and the second water intake passage 97. The second water intake passage 97 extends upward from the second water intake 96, and when the boat is moving fast, water that flows forcefully into the second water intake 96 flows up through the second water intake passage 97 and reaches the second heat exchanger 98. Then, the refrigerant in the indirect cooling system 71 is cooled by the second heat exchanger 98.

[0088] According to the electric propulsion device 90 of the second embodiment of the present invention, by providing two heat exchangers 95, 98 in the direct cooling system 92 of the cooling device 91, the cooling capacity of the refrigerant by the cooling device 91 can be increased.

[0089] In the above embodiments, an example has been given in which the refrigerant flows through the motor cooling jacket 72, the inverter cooling jacket 73, and the reduction gear cooling jacket 74 in this order in the indirect cooling system 71, but the order in which the refrigerant flows through these multiple cooling jackets is not limited.

[0090] In addition, in the above-described embodiments, the indirect cooling system 71 cools the motor 3, the inverter 6, and the reduction gear 11, but the present invention is not limited to this. For example, the indirect cooling system 71 may cool only the motor 3 or only the inverter 6, or additional equipment other than the motor 3, the inverter 6, and the reduction gear 11 may be added to the equipment to be cooled in the indirect cooling system 71.

[0091] Furthermore, in each of the above embodiments, the axial flow impeller 69 is provided in the cooling water outflow chamber 63 of the heat exchanger 55 (95), but the present invention is not limited to this, and the axial flow impeller 69 may be provided between the cooling water outflow chamber 63 and the hub 22 of the propeller 21, or within the hub 22 of the propeller 21. Furthermore, the number of cooling pipes 65 that form the cooling water passage 64 of the heat exchanger 55 is not limited.

[0092] Furthermore, although the electric propulsion unit 1 (90) in each of the above embodiments is an outboard motor, the present invention can also be applied to other types of electric marine propulsion units, such as an outboard inboard motor.

[0093] Furthermore, the present invention may be modified as appropriate within the scope of the claims and the spirit or concept of the invention as can be read from the entire specification, and electric propulsion devices with such modifications are also included in the technical concept of the present invention. [Explanation of symbols]

[0094] 1, 90 electric propulsion machine 3 motors 18 Propeller shaft 21 Propeller 22 Hub 27 Lower case 30 Propeller shaft accommodation hole 31 Shaft housing 36 Skeg 51, 91 Cooling device 53, 93 Intake 54, 94 Water intake passage 55, 95 heat exchanger 61 Cooling water inlet chamber 62 Refrigerant distribution room 63 Cooling water outflow chamber 64 Cooling water passage 65 Cooling pipe 67 Refrigerant passage 68 Baffle plate 69 Axial flow impeller 71 Indirect cooling system 72 Motor cooling jacket 81~86 Connecting passage (circulating passage) 98 Second Heat Exchanger

Claims

1. a motor that rotates the propeller; a propeller shaft disposed below the motor and having the propeller provided at its rear; a lower case that accommodates a front portion of the propeller shaft; a cooling device that cools the motor, The cooling device is a heat exchanger that uses water outside the electric propulsion device as cooling water to cool a refrigerant; a motor cooling jacket provided on the motor and configured to cool the motor using the refrigerant; a circulation passage for circulating the refrigerant between the heat exchanger and the motor cooling jacket, The electric propulsion device, wherein the heat exchanger is provided inside the lower case.

2. The electric propulsion device according to claim 1, wherein the heat exchanger is provided inside the lower case on an outer circumferential side of the propeller shaft.

3. 3. The electric propulsion according to claim 2, wherein the heat exchanger includes a cooling water passage through which the cooling water flows in the axial direction of the propeller shaft, and a refrigerant passage through which the refrigerant flows in the circumferential direction of the propeller shaft.

4. 4. The electric propulsion according to claim 3, wherein the cooling water passage has a plurality of cooling pipes through which the cooling water flows, and each of the cooling pipes is arranged to pass through the refrigerant flowing in the refrigerant passage.

5. 4. The electric propulsion according to claim 3, wherein a propeller shaft accommodating hole extending in the front-rear direction is provided in a lower part of the lower case, a cylindrical shaft housing that rotatably supports the propeller shaft is provided within the propeller shaft accommodating hole, and the cooling water passage and the refrigerant passage are provided between the propeller shaft accommodating hole and the shaft housing.

6. the space between the propeller shaft accommodating hole and the propeller shaft is divided by the shaft housing into a cooling water inlet chamber located in the front part of the space, a refrigerant circulation chamber located in the middle part of the space in the front-rear direction, and a cooling water outlet chamber located in the rear part of the space, 6. The electric propulsion according to claim 5, wherein the refrigerant passage is formed within the refrigerant flow chamber, an inlet end of the cooling water passage communicates with the cooling water inlet chamber, an outlet end of the cooling water passage communicates with the cooling water outlet chamber, and the cooling water passage passes through the refrigerant flow chamber without communicating with the refrigerant flow chamber.

7. the cooling device includes a water intake port that takes water from outside the electric propulsion into the electric propulsion, and a water intake passage that connects the water intake port and the cooling water inlet chamber, The water intake is provided in a front portion of a portion where the lower case and the skeg are joined to each other, 7. The electric propulsion device according to claim 6, wherein the water intake passage extends in the front-rear direction between the lower case and the skeg.

8. the cooling device includes an axial flow impeller that rotates integrally with the propeller shaft, the cooling water outflow chamber communicates with the inside of the propeller hub; 7. The electric propulsion device according to claim 6, wherein the axial flow impeller is disposed within the cooling water outlet chamber, between the cooling water outlet chamber and the propeller hub, or within the propeller hub.

9. 7. The electric propulsion device according to claim 6, wherein a baffle plate is provided in the refrigerant flow chamber to cause the refrigerant to flow in a zigzag pattern within the refrigerant flow chamber.

10. the cooling device includes two of the heat exchangers; 2. The electric propulsion device according to claim 1, wherein one of the two heat exchangers is provided inside the lower case on an outer circumferential side of the propeller shaft, and the other heat exchanger is provided inside the lower case above the propeller shaft.

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