ELECTRIC OUTBOARD MOTOR

Abstract

An electric outboard motor for propelling a boat. The electric outboard motor includes an outer case provided at a lower portion of the electric outboard motor and having a cylindrical portion formed in a cylindrical shape with an axis extending in a front-rear direction, a propeller rotatably supported on the outer case; and a motor provided inside the cylindrical portion and configured to rotate the propeller. The motor includes an output shaft extending in the front-rear direction, a rotor provided on an outer periphery of the output shaft, a stator provided on an outer periphery of the rotor, and a motor case in which the output shaft, the rotor, and the stator are disposed, the motor case being formed in a cylindrical shape having an axis extending in the front-rear direction.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based on and claims priority under 35 USC 119 from Japanese Patent Application No. 2025-015015 filed on January 31, 2025, the entire content of which is incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to an electric outboard motor.

BACKGROUND ART

An electric outboard motor is known that is equipped with a motor (electric motor) as a power source for rotating a propeller. In some electric outboard motors, the motor is located on a lower portion of the electric outboard motor, that is, a portion of the electric outboard motor that is submerged in the water. JPH10-16886A describes a boat propulsion device equivalent to such an electric outboard motor.

The boat propulsion device described in the above publication is provided with an electric drive unit at its lower portion. The electric drive unit has a casing that forms its outer shell, and an electric motor is accommodated inside the casing. The electric motor includes a motor case that forms part of a stator, a rotor accommodated in the motor case, and the like. The electric motor is fixed to the casing by connecting a support piece provided at a front end of the motor case to a partition plate of the casing using a bolt.

Generally, when fixing a motor to a device equipped with a motor, a flange or bracket that protrudes outward from an outer periphery of a motor case having a cylindrical shape is provided on the motor case, and the motor is fixed to the device by connecting the flange or bracket to a housing of the device or the like. In the boat propulsion device described in the above publication, the electric motor is fixed to the casing by connecting the support piece that protrudes outward (downward) from the outer periphery of the front end of the motor case to the partition plate of the casing.

However, when a motor is mounted inside an outer case that is provided at a lower portion of an electric outboard motor and forms an outer shell of a lower part of the electric outboard motor, and the motor is fixed to the outer case by providing a flange or bracket that protrudes outward from an outer periphery of a motor case on the motor case of the motor and connecting the flange or bracket to the inside of the outer case, up-down or left-right dimensions of the outer case will increase depending on an amount of protrusion of the flange or bracket that protrudes outward from the outer periphery of the motor case. Increasing a size of the outer case by increasing up-down or left-right dimensions of the outer case in this way has disadvantages such as increasing water resistance when a boat is propelled.

SUMMARY OF INVENTION

Aspect of non-limiting embodiments of the present disclosure relates to provide an electric outboard motor that can prevent an outer case that accommodates a motor from becoming too large.

Aspects of certain non-limiting embodiments of the present disclosure address the features discussed above and/or other features not described above. However, aspects of the non-limiting embodiments are not required to address the above features, and aspects of the non-limiting embodiments of the present disclosure may not address features described above.

According to an aspect of the present disclosure, there is provided an electric outboard motor for propelling a boat, the electric outboard motor including:

an outer case provided at a lower portion of the electric outboard motor and having a cylindrical portion formed in a cylindrical shape with an axis extending in a front-rear direction;

a propeller rotatably supported on the outer case; and

a motor provided inside the cylindrical portion and configured to rotate the propeller,

in which the motor includes:

an output shaft extending in the front-rear direction;

a rotor provided on an outer periphery of the output shaft;

a stator provided on an outer periphery of the rotor; and

a motor case in which the output shaft, the rotor, and the stator are disposed, the motor case being formed in a cylindrical shape having an axis extending in the front-rear direction,

a fixing portion is provided on the motor case, the fixing portion being disposed on one side of the stator in the front-rear direction and overlapping with the stator when the motor is viewed from the one side in the front-rear direction,

a protrusion is provided on the cylindrical portion, the protrusion protruding inward from an inner peripheral surface of the cylindrical portion to a position overlapping with the fixing portion of the motor provided inside the cylindrical portion when the cylindrical portion is viewed from the one side in the front-rear direction, and

the motor is fixed to the outer case by connecting the fixing portion to the protrusion.

BRIEF DESCRIPTION OF DRAWINGS

Exemplary embodiment(s) of the present invention will be described in detail based on the following figures, wherein:

FIG. 1 is an explanatory diagram illustrating an electric outboard motor according to a first example of the present disclosure;

FIG. 2 is a cross-sectional view of a lower unit of the electric outboard motor according to the first example of the present disclosure;

FIG. 3 is a cross-sectional view illustrating a cylindrical portion of an outer case body, a motor, and a motor support member of the electric outboard motor according to the first example of the present disclosure;

FIG. 4 is an explanatory diagram illustrating the motor and the motor support member of the electric outboard motor according to the first example of the present disclosure;

FIG. 5A is a cross-sectional view illustrating the motor support member of the electric outboard motor of the first example of the present disclosure taken along a line Va-Va in FIG. 4;

FIG. 5B is a cross-sectional view illustrating the motor support member taken along a line Vb-Vb in FIG. 5A;

FIG. 6A is an external view illustrating the motor of the electric outboard motor according to the first example of the present disclosure as viewed from the front;

FIG. 6B is a cross-sectional view illustrating the motor taken along a line VIb-VIb in FIG. 6A;

FIG. 7A is an external view illustrating the outer case body of the electric outboard motor according to the first example of the present disclosure as viewed from the front;

FIG. 7B is a cross-sectional view illustrating the outer case body taken along a line VIIb-VIIb in FIG. 7A;

FIG. 8 is a cross-sectional view illustrating a cylindrical portion of an outer case body, a motor, and the like in an electric outboard motor according to a second example of the present disclosure;

FIG. 9A is an explanatory diagram illustrating another example of the present disclosure; and

FIG. 9B is an explanatory diagram illustrating the other example of the present disclosure.

DESCRIPTION OF EMBODIMENTS

An electric outboard motor according to an embodiment of the present disclosure includes an outer case provided at a lower portion of the electric outboard motor. The outer case has a cylindrical portion formed in a cylindrical shape with an axis extending in a front-rear direction. The electric outboard motor of this embodiment also includes a propeller rotatably supported on the outer case, and a motor disposed inside the cylindrical portion of the outer case for rotating the propeller. The motor also has an output shaft extending in the front-rear direction, a rotor provided on an outer periphery of the output shaft, a stator provided on an outer periphery of the rotor, and a motor case formed in a cylindrical shape with an axis extending in the front-rear direction, with the output shaft, rotor, and stator arranged inside.

In the electric outboard motor of this embodiment, the motor case is provided with a fixing portion. The fixing portion is disposed on one side of the stator in the front-rear direction of the motor, and is positioned so as to overlap with the stator when the motor is viewed from the one side in the front-rear direction. In addition, a protrusion is provided on the cylindrical portion of the outer case. The protrusion protrudes inward from an inner peripheral surface of the cylindrical portion of the outer case. Furthermore, when the cylindrical portion of the outer case is viewed from the one side in the front-rear direction, the protrusion protrudes to a position where the protrusion overlaps with the fixing portion of the motor provided inside the cylindrical portion. The motor is fixed to the outer case by connecting the fixing portion of the motor to the protrusion of the outer case.

In the electric outboard motor of this embodiment, when the cylindrical portion of the outer case and the motor arranged in the cylindrical portion of the outer case are viewed from the one side in the front-rear direction, the protrusion of the outer case protrudes from the inner peripheral surface of the cylindrical portion of the outer case to a position overlapping with the stator of the motor, the fixing portion of the motor is arranged at a position overlapping with the stator of the motor, the protrusion of the outer case and the fixing portion of the motor are connected to each other at a position overlapping with the stator of the motor, and the motor is fixed to the outer case by this connection between the protrusion and the fixing portion.

As described above, in the electric outboard motors of the related art, a motor case of a motor is provided with a flange or bracket that protrudes outward from an outer periphery of the motor case, and the flange or bracket is connected to the inside of an outer case to fix the motor to the outer case. However, in the electric outboard motor of this embodiment, the motor can be fixed to the outer case without providing a flange or bracket that protrudes outward from the outer periphery of the motor case. Therefore, in the electric outboard motors of the related art, up-down or left-right dimensions of the outer case increase depending on an amount of protrusion of the flange or bracket that protrudes outward from the outer periphery of the motor case, resulting in a larger outer case. However, in the electric outboard motor of this embodiment, up-down and left-right dimensions of the outer case can be made closer to up-down and left-right dimensions of the motor, respectively, and therefore it is possible to prevent the up-down and left-right dimensions of the outer case from increasing in size, thereby preventing the outer case from becoming larger.

In the electric outboard motor of this embodiment, the fixing portion may be disposed on one side of the rotor in the front-rear direction of the motor, so as to overlap with the rotor when the motor is viewed from the one side in the front-rear direction. Even when the fixing portion is located in such a position, the motor can be fixed to the outer case without providing a flange or bracket that protrudes outward from the outer periphery of the motor case, thereby preventing the outer case from increasing in size by preventing an increase in the up-down and left-right dimensions of the outer case.

First Embodiment

Several examples of the present disclosure will be described with reference to the drawings. For ease of description, when describing directions of up (Ud), down (Dd), front (Fd), back (Bd), left (Ld), and right (Rd) in each example, the arrows drawn at the bottom left of each figure will be used.

Electric Outboard Motor

FIG. 1 illustrates an electric outboard motor 1 according to a first embodiment of the present disclosure. The electric outboard motor 1 is a device configured to propel a boat and is attached to the boat. As illustrated in FIG. 1, the electric outboard motor 1 includes a lower unit 2, an operating handle 71, a connecting portion 73, a clamp bracket 74, and a swivel bracket 75.

The lower unit 2 is a unit provided at a lower portion of the electric outboard motor 1. The lower unit 2 is provided with a propeller 21, a motor 31, and the like. The operating handle 71 is a handle for operating the electric outboard motor 1 and is provided on an upper portion of the electric outboard motor 1. The connecting portion 73 is a member that connects the lower unit 2 and the operating handle 71, and is formed in a columnar or cylindrical shape that extends in an up-down direction. The clamp bracket 74 is a mechanism for attaching and fixing the electric outboard motor 1 to a transom of the boat. The swivel bracket 75 is a mechanism configured to support the connecting portion 73 such that the connecting portion 73 can pivot about its axis A. The swivel bracket 75 is connected to the clamp bracket 74.

When the electric outboard motor 1 is attached to the transom of the boat and the boat is stopped, the lower unit 2 is located below the water surface, and the operating handle 71, the clamp bracket 74, and the swivel bracket 75 are located above the water surface. An operator can change rotation speed and rotation direction of the motor 31 provided in the lower unit 2 by grasping a grip 72 provided at a tip of the operating handle 71 and pivoting the grip 72 around its axis B. By changing the rotation speed of the motor 31, the rotation speed of the propeller 21 can be changed, and the speed of the boat can be changed. Furthermore, by changing the rotation direction of the motor 31, the rotation direction of the propeller 21 can be changed, and the boat can be switched between forward and reverse motion. In addition, the operator can grasp the grip 72 and pivot the operating handle 71 around the axis A of the connecting portion 73 to pivot the lower unit 2 horizontally and change the direction of the propeller 21 provided on the lower unit 2. By changing the direction of the propeller 21, the boat can be turned.

Lower Unit

FIG. 2 illustrates a cross section of the lower unit 2 as viewed from the left, taken along a plane that passes through a center of the lower unit 2 in a left-right direction and extends in up-down and front-rear directions.

As illustrated in FIG. 2, the lower unit 2 includes an outer case 3, the propeller 21, a propeller shaft 25, a plurality of (for example, two) bearings 28 configured to support the propeller shaft 25, the motor 31, a reduction gear 45, and an inverter 46.

The outer case 3 forms an outer shell of the lower unit 2. When the electric outboard motor 1 is mounted on the transom of the boat and the boat is stationary, the outer case 3 is placed in water. The outer case 3 is made of a metal material such as aluminum. As illustrated in FIG. 1, the outer case 3 includes an outer case body 4, a lid portion 9, and a reduction gear case portion 12.

The outer case body 4 has a cylindrical portion 5 formed in a cylindrical shape with an axis extending in the front-rear direction, and a columnar portion 6 formed in a columnar shape extending upward from the cylindrical portion 5. A skeg 7 is integrally formed or attached to a lower end of the cylindrical portion 5. An anti-cavitation plate 8 is integrally formed or attached to an upper portion of the columnar portion 6.

The lid portion 9 is formed in a cup shape and is attached to a front end of the cylindrical portion 5 of the outer case body 4 using a connecting member 10 such as a bolt. A front opening of the cylindrical portion 5 is closed by the lid portion 9. As illustrated in FIG. 2, a seal 11 (for example, a sealing member such as an O-ring) is provided between the cylindrical portion 5 and the lid portion 9 to prevent water from entering the outer case 3.

As illustrated in FIG. 1, the reduction gear case portion 12 has an axis extending in the front-rear direction and is formed in a cylindrical shape of which a diameter decreases toward the rear. The reduction gear case portion 12 is attached to a rear end of the cylindrical portion 5 of the outer case body 4 using a connecting member 13 such as a bolt. As illustrated in FIG. 2, a seal 14 (for example, a sealing member such as an O-ring) is provided between the cylindrical portion 5 and the reduction gear case portion 12 to prevent water from entering the outer case 3. The seal 14 also has a function of preventing lubricating oil in the reduction gear case portion 12 from leaking out of the outer case 3.

Further, an inverter accommodating portion 15, a motor accommodating portion 16, a reduction gear accommodating portion 17, and a bearing accommodating portion 18 are provided inside the outer case 3. Specifically, the inverter accommodating portion 15 and the motor accommodating portion 16 are provided inside the cylindrical portion 5 of the outer case body 4. The reduction gear accommodating portion 17 and the bearing accommodating portion 18 are provided inside the reduction gear case portion 12. The inverter accommodating portion 15 is disposed in front of the motor accommodating portion 16, and the inverter accommodating portion 15 and the motor accommodating portion 16 are adjacent to each other. The reduction gear accommodating portion 17 is disposed behind the motor accommodating portion 16, and the reduction gear accommodating portion 17 and the motor accommodating portion 16 are adjacent to each other. The bearing accommodating portion 18 is disposed behind the reduction gear accommodating portion 17, and the bearing accommodating portion 18 and the reduction gear accommodating portion 17 are adjacent to each other.

The propeller 21 is configured to generate propulsive force for the boat by rotating. The propeller 21 is disposed at the rear of the outer case 3 and is rotatably supported by the outer case 3 via the propeller shaft 25 and the bearing 28. The propeller 21 has a hub 22 and a plurality of blades 23. The propeller shaft 25 extends in the front-rear direction. A front portion of the propeller shaft 25 is disposed inside the outer case 3, specifically, in a portion from the reduction gear accommodating portion 17 to the bearing accommodating portion 18 inside the outer case 3. The plurality of bearings 28 are disposed inside the bearing accommodating portion 18 of the outer case 3. The front portion of the propeller shaft 25 is rotatably supported by the plurality of bearings 28 on the reduction gear case portion 12 of the outer case 3. In addition, the propeller 21 is attached and fixed to a rear end side of the propeller shaft 25. The propeller 21 is secured to the propeller shaft 25 by a cotter pin 26 and a propeller nut 27. In addition, a seal 29 (sealing member, sealing mechanism, or the like) is provided between a rear end of the reduction gear case portion 12 and the propeller shaft 25 to prevent water from entering the reduction gear case portion 12. The seal 29 also has a function of preventing the lubricating oil in the reduction gear case portion 12 from leaking out of the outer case 3.

The motor 31 is a power source that rotates the propeller 21. The motor 31 is disposed inside the cylindrical portion 5 of the outer case 3, specifically inside the motor accommodating portion 16. The motor 31 is, for example, an AC motor. The motor 31 includes an output shaft 32, a rotor 33, a stator 34, a motor case 35, a bearing 40, and a bearing 41.

The output shaft 32 extends in the front-rear direction. The output shaft 32 is rotatably supported by the motor case 35 via the bearing 40 and the bearing 41. The output shaft 32 and the propeller shaft 25 are arranged coaxially with each other, that is, an axis of the output shaft 32 and an axis of the propeller shaft 25 are both axis C. The bearing 40 is disposed at a front end of the motor 31. The front end of the output shaft 32 is rotatably supported by the bearing 40 on a bottom portion 36A of a motor case body 36 of the motor case 35. The bearing 41 is disposed at a rear end of the motor 31. A rear end portion of the output shaft 32 is rotatably supported by a closing member 38 of the motor case 35 via the bearing 41. The rotor 33 and the stator 34 are disposed in the middle of the motor 31 in the front-rear direction. The rotor 33 is located on an outer periphery of the output shaft 32 and rotates integrally with the output shaft 32. The stator 34 is located on an outer periphery of the rotor 33 and is fixed to the motor case body 36 of the motor case 35.

The motor case 35 is a case that accommodates the output shaft 32, the rotor 33, the stator 34, the bearing 40, and the bearing 41. The output shaft 32, the rotor 33, the stator 34, the bearing 40, and the bearing 41 are disposed in the motor case 35. The motor case 35 has the motor case body 36 and the closing member 38. The motor case body 36 is formed from a metal material such as steel or aluminum. The motor case body 36 is formed in a cylindrical shape having an axis extending in the front-rear direction. Specifically, the motor case body 36 is formed in a cylindrical shape with a bottom, and is disposed so that a bottom on one axial side faces forward and an opening on the other axial side faces rearward. In addition, a hole is provided in a center of the bottom of the motor case body 36. The closing member 38 is a disk-shaped member with a hole in the center, and is attached to a rear end of the motor case body 36. In addition, a seal 39 (for example, a sealing member such as an O-ring) is provided between the motor case body 36 and the closing member 38 to prevent the lubricating oil in the reduction gear case portion 12 from entering the motor 31. The output shaft 32 passes through the hole provided in the center of the closing member 38 and protrudes rearward from inside the motor case 35 to outside the motor case 35. In addition, a seal 42 (sealing member, sealing mechanism, or the like) is provided between the closing member 38 and the output shaft 32 to prevent the lubricating oil in the reduction gear case portion 12 from entering the motor 31.

The reduction gear 45 is a device configured to transmit the rotation of the output shaft 32 to the propeller shaft 25 while reducing the rotation speed, and has, for example, a planetary reduction mechanism. The reduction gear 45 is disposed in the reduction gear accommodating portion 17 of the outer case 3.

The inverter 46 is a device configured to control the driving of the motor 31. The inverter 46 is configured to output a driving current to the motor 31 to drive the motor 31. The inverter 46 is disposed in the inverter accommodating portion 15 of the outer case 3. In this example, the inverter 46 is attached to a front surface of the motor case 35. Furthermore, a signal cable 47 for transmitting a control signal to the inverter 46 and a power cable 48 for supplying power to the inverter 46 are connected to the inverter 46.

Motor Support and Fixing

A structure for supporting and fixing the motor 31 to the outer case body 4 will be described with reference to FIGS. 3 to 7B. FIG. 3 illustrates the cylindrical portion 5 of the outer case body 4, the motor 31, and the motor support member 53 in FIG. 2. FIG. 3 illustrates a state in which a fastening member 63 is removed from the outer case body 4 and the motor 31. FIG. 4 illustrates the motor 31 and the motor support member 53 separated from each other as viewed from the left. FIG. 5A illustrates a cross section of the motor support member 53 taken along a line Va-VaE in FIG. 4, as viewed from the front (left in FIG. 4). FIG. 5B illustrates a cross section of the motor support member 53 taken along a line Vb-Vb in FIG. 5A, as viewed from the left (right in FIG. 5A). FIG. 6A illustrates the motor 31 as viewed from the front. FIG. 6B illustrates a cross section of the motor 31 taken along a line VIb-VIb in FIG. 6A, as viewed from the left (right in FIG. 6A). FIG. 7A illustrates the outer case body 4 as viewed from the front. FIG. 7B illustrates a cross section of the outer case body 4 taken along a line VIIb-VIIb in FIG. 7A, as viewed from the left (right in FIG. 7A).

As illustrated in FIG. 3, the motor 31 is supported inside the cylindrical portion 5 of the outer case body 4 by a motor support portion 51 provided at a front end portion of the motor 31 and the motor support member 53 provided at a rear end portion of the motor 31.

That is, as illustrated in FIG. 4, the motor support portion 51 is provided at a front end portion of the motor case 35. The motor support portion 51 protrudes radially outward from an outer peripheral surface of the front end portion of the motor case 35 and extends around the entire periphery of the motor case 35. The motor support portion 51 is integrally formed with the motor case 35.

The motor support member 53 is provided at a rear end portion of the motor case 35. As illustrated in FIGS. 4, 5A, and 5B, the motor support member 53 is formed in a cylindrical shape with a bottom, and is positioned so that the opening on one axial side faces forward and the bottom on the other axial side faces backward. A central hole 54 is formed in a center of the bottom of the motor support member 53. Furthermore, an axial length L1 of the motor support member 53 is shorter than an axial length L2 of the motor case 35. An inner diameter D1 of the motor support member 53 is set to a value substantially equal to an outer diameter D3 of the rear end portion of the motor case 35 so that the rear end portion of the motor case 35 fits inside the motor support member 53. The outer diameter D2 of the motor support member 53 is set to a value larger than the outer diameter D3 of the rear end portion of the motor case 35. The rear end portion of the motor case 35 fits inside the motor support member 53. In this manner, the motor support member 53 is attached to the rear end portion of the motor case 35. As illustrated in FIG. 3, in a state where the motor support member 53 is attached to the rear end portion of the motor case 35, the motor support member 53 protrudes radially outward from the outer peripheral surface of the rear end portion of the motor case 35. The output shaft 32 also passes through the central hole 54 in the motor support member 53.

As illustrated in FIG. 3, in a state where the motor 31 to which the motor support member 53 is attached is placed inside the cylindrical portion 5 of the outer case body 4, outer peripheral surfaces of the motor support portion 51 and the motor support member 53 are in contact with an inner peripheral surface of the cylindrical portion 5. As a result, the motor 31 is supported within the cylindrical portion 5 so as not to move in a radial direction.

As illustrated in FIG. 6B, in the motor case 35 of the motor 31, the bottom portion 36A of the motor case body 36 is provided with a fastening hole 61 for fixing the motor 31 to the outer case body 4. As illustrated in FIG. 6A, a plurality of (for example, three) fastening holes 61 are provided. The plurality of fastening holes 61 are arranged at predetermined intervals (for example, at intervals of 120 degrees) in a circumferential direction on an outer periphery of a front end of the output shaft 32. Each fastening hole 61 extends in the front-rear direction and opens to a front surface (outer surface of the bottom portion 36A) of the motor case body 36. As illustrated in FIG. 6B, each fastening hole 61 is disposed in front of the stator 34 in the motor 31. Furthermore, each fastening hole 61 is disposed at a position that overlaps with the stator 34 when the motor 31 is viewed from the front. Furthermore, each fastening hole 61 is disposed on an outer periphery side of the bearing 40, and positions of each fastening hole 61 and the bearing 40 in the front-rear direction are aligned with each other. Each fastening hole 61 is formed with a screw for fastening the fastening member 63. The fastening hole 61 is a specific example of a "fixing portion".

As illustrated in FIG. 7B, the cylindrical portion 5 of the outer case body 4 is provided with a protrusion 62 for fixing the motor 31 to the outer case body 4. As illustrated in FIG. 7A, the cylindrical portion 5 is provided with the same number of (for example, three) protrusions 62 as the number of fastening holes 61 of the motor 31. The plurality of protrusions 62 are arranged at predetermined intervals (for example, at intervals of 120 degrees) in the circumferential direction. Circumferential positions of the plurality of protrusions 62 respectively coincide with circumferential positions of the plurality of fastening holes 61. As illustrated in FIG. 7B, each protrusion 62 protrudes radially inward from the inner peripheral surface of the cylindrical portion 5 at a boundary between the inverter accommodating portion 15 and the motor accommodating portion 16. Furthermore, when the cylindrical portion 5 is viewed from the front, each protrusion 62 protrudes inward to a position where the protrusion overlaps with the fastening hole 61 of the motor 31 arranged inside the cylindrical portion 5 (see FIG. 3). Each protrusion 62 has an insertion hole 62A. When the cylindrical portion 5 is viewed from the front, positions of the insertion holes 62A of the protrusions 62 coincide with the positions of the fastening holes 61 of the motor 31 arranged inside the cylindrical portion 5.

As illustrated in FIG. 3, in a state where the motor 31 is disposed in the motor accommodating portion 16 of the cylindrical portion 5 of the outer case body 4, the fastening hole 61 of the motor 31 is disposed behind the protrusion 62 of the outer case body 4. The motor 31 is fixed to the outer case body 4 by inserting the fastening member 63, such as a bolt, from the front into the insertion hole 62A of the protrusion 62 of the outer case body 4, and then inserting the fastening member 63 into the fastening hole 61 of the motor 31 and fastening the fastening member 63.

Lubrication and Cooling Structures

In FIG. 2, lubricating oil is poured into the reduction gear accommodating portion 17 and the bearing accommodating portion 18 of the outer case 3. The lubricating oil is stirred by the operation of the reduction gear 45, and the lubricating oil flows inside the reduction gear accommodating portion 17 and the bearing accommodating portion 18. As a result, the reduction gear 45 and the bearings 28 are lubricated and cooled by the lubricating oil.

A gap 59 is formed between an outer peripheral surface of the motor case body 36 of the motor 31 and the inner peripheral surface of the cylindrical portion 5 of the outer case body 4. As illustrated in FIG. 5A, the central hole 54 is formed in the center of the bottom of the motor support member 53, and a plurality of communication holes 55 are formed in an outer peripheral portion of the bottom of the motor support member 53. In addition, a plurality of notches 56 are formed on the outer peripheral surface of the motor support member 53. As illustrated in FIG. 2, the gap 59 communicates with the inside of the reduction gear accommodating portion 17 via the central hole 54 of the motor support member 53, the communication holes 55, and the notches 56. As a result, the lubricating oil flowing inside the reduction gear accommodating portion 17 flows through the central hole 54 of the motor support member 53, the communication holes 55, and the notches 56, and into the gap 59. The motor 31 is cooled by the lubricating oil flowing through the gap 59.

As illustrated in FIG. 4, two grooves, for example, are formed around the entire periphery of the outer peripheral surface of the motor support portion 51 of the motor 31, and a seal 52 (for example, a sealing member such as an O-ring) is provided in each groove. As illustrated in FIG. 2, the seal 52 is in liquid-tight contact with the inner peripheral surface of the cylindrical portion 5 (motor accommodating portion 16) over the entire periphery. The seal 52 has a function of preventing the lubricating oil P flowing in the gap 59 from leaking from the gap 59 into the inverter accommodating portion 15.

As illustrated in FIG. 2, the reduction gear case portion 12 is provided with a drain bolt hole 57 for discharging lubricating oil from the reduction gear accommodating portion 17 or the like to the outside of the outer case 3, or for injecting lubricating oil from the outside of the outer case 3 into the reduction gear accommodating portion 17 or the like, and a drain bolt 58 is fastened to the drain bolt hole 57.

Motor Installation/Removal

The motor 31 is detachable from the outer case 3. The motor 31 can be removed from the outer case 3, for example, in the following manner. In FIG. 2, first, the cotter pin 26 and the propeller nut 27 are removed, and the propeller 21 is removed from the propeller shaft 25. Next, the drain bolt 58 is removed, and the lubricating oil in the reduction gear accommodating portion 17 and the like is drained out of the outer case 3 through the drain bolt hole 57. Next, the connecting member 13 is removed, and the reduction gear case portion 12 is removed from the outer case body 4. By removing the reduction gear case portion 12 from the outer case body 4, the reduction gear 45 and the propeller shaft 25 are separated from the output shaft 32. Next, the connecting member 10 (see FIG. 1) is removed, and the lid portion 9 is removed from the outer case body 4. Next, the fastening member 63 that fixes the motor 31 to the outer case body 4 is removed. Next, the motor 31 is pulled out from the opening at the rear side of the outer case body 4.

The motor 31 can be attached to the outer case 3, for example, by the following method. First, the motor 31 is inserted into the outer case body 4 through the opening at the rear side of the outer case body 4. Next, the fastening member 63 is fastened to fix the motor 31 to the outer case body 4. Next, the lid portion 9 is attached to the outer case body 4 and the connecting member 10 is fastened to fix the lid portion 9 to the outer case body 4. Next, the reduction gear 45 and the propeller shaft 25 are connected to the output shaft 32, and the reduction gear case portion 12 is attached to the outer case body 4. Then, the connecting member 13 is fastened to fix the reduction gear case portion 12 to the outer case body 4. Next, lubricating oil is poured in through the drain bolt hole 57, and after the pouring is completed, the drain bolt 58 is tightened in the drain bolt hole 57. Next, the propeller 21 is attached to the propeller shaft 25, the propeller nut 27 is fastened to the propeller shaft 25, and the cotter pin 26 is attached.

As described above, in the electric outboard motor 1 of the first example of the present disclosure, the motor case 35 is provided with the fastening hole 61 for fixing the motor 31 to the outer case body 4, and the fastening hole 61 is disposed forward of the stator 34 in a position that overlaps with the stator 34 when the motor 31 is viewed from the front. In addition, the cylindrical portion 5 of the outer case body 4 is provided with the protrusion 62 for fixing the motor 31 to the outer case body 4, the protrusion 62 protruding inward from the inner peripheral surface of the cylindrical portion 5, and the protrusion 62 protruding to a position where the protrusion overlaps with the fastening hole 61 of the motor 31 provided within the cylindrical portion 5 when the cylindrical portion 5 is viewed from the front. The motor 31 is fixed to the outer case body 4 by inserting the fastening member 63 inserted into then insertion hole 62A formed in the protrusion 62 into the fastening hole 61 and fastening the fastening member 63. As described above, in the electric outboard motors of the related art, a motor case of a motor is provided with a flange or bracket that protrudes outward from an outer periphery of the motor case, and the flange or bracket is connected to the inside of an outer case to fix the motor to the outer case. However, in the electric outboard motor 1 of this example, the motor 31 can be fixed to the outer case body 4 without providing a flange or bracket that protrudes outward from the outer periphery of the motor case 35. Therefore, in the electric outboard motors of the related art, up-down or left-right dimensions of the outer case increase depending on an amount of protrusion of the flange or bracket that protrudes outward from the outer periphery of the motor case, resulting in a larger outer case. However, in the electric outboard motor 1 of this example, up-down and left-right dimensions of the outer case body 4 can be made closer to up-down and left-right dimensions of the motor 31, respectively, and therefore it is possible to prevent the up-down and left-right dimensions of the outer case body 4 from increasing in size, thereby preventing the outer case 3 from becoming larger.

In the electric outboard motor 1 of this example, the motor 31 is disposed inside the outer case 3, and the propeller 21 is disposed behind the outer case 3. Furthermore, in the motor 31, the fastening hole 61 is disposed forward of the stator 34, and the protrusion 62 of the outer case body 4 is disposed in front of the fastening hole 61 of the motor 31. This configuration can prevent the outer case 3 from increasing in size in the front-rear dimension, and can prevent the outer case 3 from becoming too large. That is, when the propeller 21 is positioned behind the outer case 3, the bearing 28 for supporting the propeller shaft 25 and the reduction gear 45 for transmitting the power of the motor 31 to the propeller shaft 25 are arranged at the rear portion (the part behind the motor 31 within the outer case 3) of the outer case 3. When the fastening hole 61 in the motor 31 is positioned behind the stator 34 and the protrusion 62 of the outer case body 4 is positioned behind the fastening hole 61 of the motor 31, it is necessary to shift the position of the reduction gear 45 and bearing 28 rearward to secure space for the protrusion 62, and as a result, the front-rear dimension of the outer case 3 increases. On the other hand, a larger empty space exists in the front part (the part in front of the motor 31 inside the outer case 3) of the outer case 3 compared to the rear part of the outer case 3. Therefore, when the fastening hole 61 in the motor 31 is positioned forward of the stator 34 and the protrusion 62 of the outer case body 4 is positioned in front of the fastening hole 61 of the motor 31, the protrusion 62 can be provided in the empty space in the front part of the outer case 3, and as a result, the increase in the front-rear dimension of the outer case 3 can be suppressed.

Furthermore, in the electric outboard motor 1 of this example, the bearing 40 is provided inside the motor case 35 to rotatably support the front end portion of the output shaft 32, and the fastening hole 61 is located on the outer periphery side of the bearing 40, with the fastening hole 61 and the bearing 40 being positioned in the same position in the front-rear direction. This configuration can prevent the fastening hole 61 from interfering with the rotor 33 or the stator 34, while suppressing an increase in the front-rear dimension of the motor 31. That is, in the motor 31, the rotor 33 and the stator 34 are positioned rearward of the bearing 40, so by providing the fastening hole 61 on the outer periphery side of the bearing 40, it is possible to prevent the fastening hole 61 from interfering with the rotor 33 or the stator 34. Furthermore, by aligning the position of the fastening hole 61 in the front-rear direction with the position of the bearing 40 in the front-rear direction, the front-rear dimension of the motor 31 can be reduced compared to when the position of the fastening hole 61 in the front-rear direction is different from the position of the bearing 40 in the front-rear direction.

In addition, in the electric outboard motor 1 of this example, the motor 31 is fixed to the outer case body 4 by inserting the fastening member 63, which is inserted into the insertion hole 62A formed in the protrusion 62, into the fastening hole 61 and fastening the fastening member 63. With this configuration, the motor 31 can be easily separated from the outer case body 4 by loosening the fastening member 63 and removing the fastening member 63 from the fastening hole 61. This allows the outer case 3 of the electric outboard motor 1 of this example to be made as small as an outer case of an electric outboard motor that employs a method of shrink-fitting a motor into the outer case, and at the same time, the motor 31 can be made detachable from the outer case 3, reducing the maintenance costs of the electric outboard motor. In other words, when the method of shrink-fitting the motor into the outer case is adopted, the up-down and left-right dimensions of the outer case can be made extremely close to the up-down and left-right dimensions of the motor, thereby making it possible to reduce the size of the outer case. However, when the method of shrink-fitting the motor to the outer case is adopted, it becomes difficult to separate the motor from the outer case, which has the disadvantage of increasing the maintenance costs of the electric outboard motor, for example, if the motor breaks down, the motor and the outer case must be replaced. In contrast, with the electric outboard motor 1 of this example, the up-down and left-right dimensions of the outer case 3 can be made closer to the up-down and left-right dimensions of the outer case of an electric outboard motor that employs a method in which the motor is shrink-fitted to the outer case, thereby making it possible to reduce the size of the outer case 3. In this case, since the motor 31 can be made detachable from the outer case 3, when the motor 31 breaks down, for example, the motor 31 can be removed from the outer case 3 and repaired or replaced. This eliminates the need to replace the outer case 3, thereby reducing the maintenance costs of the electric outboard motor 1.

Second Embodiment

FIG. 8 illustrates a cylindrical portion 83 of an outer case body 82 of an outer case 81, a motor 84, and the like in an electric outboard motor according to a second example of the present disclosure.

As illustrated in FIG. 8, in the motor 84, a bottom portion 86A of a motor case body 86 of a motor case 85 is provided with a fastening hole 91 for fixing the motor 84 to the outer case body 82. Similar to the fastening holes 61 of the motor 31 in the first example, three fastening holes 91 are provided, and the three fastening holes 91 are arranged in a circumferential direction at intervals of, for example, 120 degrees on an outer periphery side of a front end of the output shaft 32. Each fastening hole 91 opens to a front surface (outer surface of the bottom portion 86A) of the motor case body 86. However, unlike the fastening holes 61 of the motor 31 in the first example, each fastening hole 91 is positioned in front of a rotor 33 in the motor 84, and is positioned so as to overlap with the rotor 33 when the motor 84 is viewed from the front. The fastening hole 91 is a specific example of a "fixing portion".

In addition, in the outer case 81, a protrusion 92 for fixing the motor 84 to the outer case body 82 is provided on the cylindrical portion 83 of the outer case body 82. The number of protrusions 92 is, for example, three, the same as the number of fastening holes 91 of the motor 84, and circumferential positions of the three protrusions 92 respectively coincide with the circumferential positions of the three fastening holes 91. Each protrusion 92 protrudes radially inward from the inner peripheral surface of the cylindrical portion 83 at a boundary between an inverter accommodating portion 15 and a motor accommodating portion 16. Furthermore, when the cylindrical portion 83 is viewed from the front, each protrusion 92 protrudes inward to a position where the protrusion 92 overlaps with the fastening hole 91 of the motor 84 arranged inside the cylindrical portion 83. In addition, the insertion hole 92A is formed in each protrusion 92, and when the cylindrical portion 83 is viewed from the front, the position of the insertion hole 92A in each protrusion 92 coincides with the position of the fastening hole 91 of the motor 84 arranged inside the cylindrical portion 83.

In a state where the motor 84 is disposed in the motor accommodating portion 16 of the cylindrical portion 83, the fastening hole 91 is disposed behind the protrusion 92. The motor 84 is fixed to the outer case body 82 by inserting the fastening member 63 into the insertion hole 92A of the protrusion 92 from the front, and then inserting the fastening member 63 into the fastening hole 91 and fastening the fastening member 63.

The electric outboard motor of the second example of the present disclosure having such a configuration provides the same effects as the electric outboard motor 1 of the first example of the present disclosure.

In each of the above-described examples, the motor case body 36 (86) has the bottom portion 36A (86A) and is formed in a cylindrical shape without a lid portion, and is arranged so that the bottom portion 36A (86A) of the motor case body 36 (86) faces forward and the opening of the motor case body 36 (86) faces backward, the closing member 38 is attached to the opening of the motor case body 36 (86), and the fastening hole 61 (91) is formed in the bottom portion 36A (86A) of the motor case body 36 (86). However, the present invention is not limited to this. For example, the motor case body may be formed in a cylindrical shape with neither a bottom portion nor a lid portion, and may be arranged so that an opening on one axial side of the motor case body faces forward and an opening on the other axial side of the motor case body faces backward. Closing members may be attached to the opening on one axial side of the motor case body and the opening on the other axial side, and a fastening hole may be formed in the closing member attached to the opening on one axial side of the motor case body.

Furthermore, in the outer case body 4 (82) of each of the above-described examples, each protrusion 62 (92) protrudes inward from the inner peripheral surface of the cylindrical portion 5 (83) toward the axis of the cylindrical portion 5 (83), but the present invention is not limited to this. For example, like the protrusion 123 illustrated in FIG. 9A, the protrusion may protrude inward from the inner peripheral surface of the cylindrical portion 122 of the outer case body 121 in a direction away from the axis of the cylindrical portion 122. Furthermore, the shape of the protrusion is not limited, and may, for example, protrude inward from the inner peripheral surface of the cylindrical portion 132 of the outer case body 131 around the entire periphery, as in a protrusion 133 illustrated in FIG. 9B.

Furthermore, in each of the above-described examples, the fastening hole 61 (91) of the motor 31 (84) is positioned forward of the stator 34 (or rotor 33), and the protrusion 62 (92) of the outer case body 4 (82) is positioned in front of the fastening hole 61 (91) of the motor 31 (84), but the fastening hole of the motor may be positioned rearward of the stator (or rotor), and the protrusion of the outer case body may be positioned behind the fastening hole of the motor.

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 outboard motors with such modifications are also included within the technical concept of the present invention.

Claims

1. An electric outboard motor for propelling a boat, the electric outboard motor comprising:

an outer case provided at a lower portion of the electric outboard motor and having a cylindrical portion formed in a cylindrical shape with an axis extending in a front-rear direction;

a propeller rotatably supported on the outer case; and

a motor provided inside the cylindrical portion and configured to rotate the propeller,

wherein the motor includes:

an output shaft extending in the front-rear direction;

a rotor provided on an outer periphery of the output shaft;

a stator provided on an outer periphery of the rotor; and

a motor case in which the output shaft, the rotor, and the stator are disposed, the motor case being formed in a cylindrical shape having an axis extending in the front-rear direction,

a fixing portion is provided on the motor case, the fixing portion being disposed on one side of the stator in the front-rear direction and overlapping with the stator when the motor is viewed from the one side in the front-rear direction,

a protrusion is provided on the cylindrical portion, the protrusion protruding inward from an inner peripheral surface of the cylindrical portion to a position overlapping with the fixing portion of the motor provided inside the cylindrical portion when the cylindrical portion is viewed from the one side in the front-rear direction, and

the motor is fixed to the outer case by connecting the fixing portion to the protrusion.

2. The electric outboard motor according to claim 1, wherein the propeller is disposed rearward of the outer case, and the fixing portion is disposed forward of the stator.

3. An electric outboard motor for propelling a boat, the electric outboard motor comprising:

an outer case provided at a lower portion of the electric outboard motor and having a cylindrical portion formed in a cylindrical shape with an axis extending in a front-rear direction;

a propeller rotatably supported on the outer case; and

a motor provided inside the cylindrical portion and configured to rotate the propeller,

wherein the motor includes:

an output shaft extending in the front-rear direction;

a rotor provided on an outer periphery of the output shaft;

a stator provided on an outer periphery of the rotor; and

a motor case in which the output shaft, the rotor, and the stator are disposed, the motor case being formed in a cylindrical shape having an axis extending in the front-rear direction,

a fixing portion is provided on the motor case, the fixing portion being disposed on one side of the rotor in the front-rear direction and overlapping with the rotor when the motor is viewed from the one side in the front-rear direction,

a protrusion is provided on the cylindrical portion, the protrusion protruding inward from an inner peripheral surface of the cylindrical portion to a position overlapping with the fixing portion of the motor provided in the cylindrical portion when the cylindrical portion is viewed from the one side in the front-rear direction, and

the motor is fixed to the outer case by connecting the fixing portion to the protrusion.

4. The electric outboard motor according to claim 3, wherein the propeller is disposed rearward of the outer case, and the fixing portion is disposed forward of the rotor.

5. The electric outboard motor according to claim 1, wherein a bearing is provided inside the motor case, the bearing being configured to rotatably support one side portion of the output shaft in the front-rear direction, and the fixing portion and the bearing are positioned in the same position in the front-rear direction.

6. The electric outboard motor according to claim 1, wherein the motor case is formed in a cylindrical shape with a bottom portion, and is disposed such that the bottom portion faces the one side in the front-rear direction, the fixing portion is a fastening hole formed in the bottom portion, and the motor is fixed to the outer case by inserting a fastening member into the fastening hole to fasten the fastening member, the fastening member being inserted into an insertion hole formed in the protrusion.

7. The electric outboard motor according to claim 3, wherein a bearing is provided inside the motor case, the bearing being configured to rotatably support one side portion of the output shaft in the front-rear direction, and the fixing portion and the bearing are positioned in the same position in the front-rear direction.

8. The electric outboard motor according to claim 3, wherein the motor case is formed in a cylindrical shape with a bottom portion, and is disposed such that the bottom portion faces the one side in the front-rear direction, the fixing portion is a fastening hole formed in the bottom portion, and the motor is fixed to the outer case by inserting a fastening member into the fastening hole to fasten the fastening member, the fastening member being inserted into an insertion hole formed in the protrusion.