OUTBOARD MOTOR

Abstract

An outboard motor includes an upper unit including a drive motor and a first transmission mechanism, a lower unit including a propeller and a propeller shaft, a drive shaft extending from the upper unit to the lower unit, a connecting mechanism that connects the lower unit to the upper unit so that the lower unit is pivotable, a steering motor serving as a power source for pivoting the lower unit relative to the upper unit, and a third transmission mechanism that transmits rotation of the steering motor to the lower unit. The drive shaft is disposed in front of an output shaft of the drive motor and the steering motor is disposed below the drive motor and behind the drive shaft.

Claims

1. An outboard motor comprising: an upper unit including: a drive motor serving as a power source configured to rotate a propeller; and a first transmission mechanism configured to transmit rotation of the drive motor to a drive shaft; a lower unit including: a propeller shaft in which the propeller is provided; and a second transmission mechanism configured to transmit rotation of the drive shaft to the propeller shaft; the drive shaft extending in a vertical direction from the upper unit to the lower unit; a connecting mechanism configured to connect the lower unit to the upper unit so that the lower unit is pivotable about an axis of the drive shaft; a steering motor provided in the upper unit and serving as a power source configured to pivot the lower unit relative to the upper unit; and a third transmission mechanism provided between the upper unit and the lower unit and configured to pivot the lower unit relative to the upper unit by transmitting rotation of the steering motor to the lower unit, wherein the drive shaft is disposed in front of an output shaft of the drive motor and the steering motor is disposed below the drive motor and behind the drive shaft.

2. The outboard motor according to claim 1, wherein the steering motor is disposed so that an axis of an output shaft of the steering motor is disposed on a plane perpendicular to the axis of the drive shaft.

3. The outboard motor according to claim 1, wherein the steering motor is disposed so that an extension direction of an output shaft of the steering motor is a left-right direction of the outboard motor.

4. The outboard motor according to claim 3, wherein the third transmission mechanism includes: a worm that rotates by the rotation of the steering motor; and a worm wheel that meshes with the worm, the worm wheel is fixed to the lower unit and is disposed coaxially with the drive shaft on an outer periphery of the drive shaft, and the worm extends in the left-right direction of the outboard motor and is disposed behind the worm wheel.

5. The outboard motor according to claim 1, wherein the first transmission mechanism is disposed below the drive motor and the third transmission mechanism is disposed below the first transmission mechanism.

6. The outboard motor according to claim 1, wherein the first transmission mechanism includes: a drive gear coupled to a lower end of the output shaft of the drive motor; and a driven gear disposed in front of the drive gear, coupled to an upper end of the drive shaft, and meshing with the drive gear.

7. The outboard motor according to claim 6, further comprising: a mounting mechanism configured to mount the upper unit to a boat, wherein the mounting mechanism includes: a clamp bracket for fixing the upper unit to the boat; and a mount bracket connected to the clamp bracket, the mount bracket includes: an upper mount portion that supports an upper part of the upper unit; and a lower mount portion that supports a lower part of the upper unit, the first transmission mechanism is disposed below the drive motor, and the lower mount portion supports a portion of the lower part of the upper unit positioned above a portion of the first transmission mechanism where the driven gear is disposed.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0015] FIG. 1 is an explanatory diagram illustrating an outboard motor according to an example of the present invention as viewed from the left.

[0016] FIG. 2 is an explanatory diagram illustrating the outboard motor according to the example of the present invention as viewed from behind.

[0017] FIG. 3 is a cross-sectional view of the outboard motor cut along a line A-A in FIG. 2 as viewed from the left.

[0018] FIG. 4 is an enlarged cross-sectional view of a portion including a speed reducer, a connecting mechanism, a steering motor, and a worm gear mechanism of the outboard motor in FIG. 3.

[0019] FIG. 5A is a cross-sectional view illustrating an upper unit of the outboard motor in FIG. 4, and FIG. 5B is a cross-sectional view illustrating a lower unit of the outboard motor in FIG. 4.

[0020] FIG. 6 is a cross-sectional view of the outboard motor cut along a line B-B in FIG. 4, illustrating a middle case of the outboard motor as well as the steering motor and the worm gear mechanism disposed in the middle case as viewed from above.

DESCRIPTION OF EMBODIMENTS

[0021] An outboard motor of an embodiment of the present invention includes: an upper unit that includes a drive motor serving as a power source for rotating a propeller and a first transmission mechanism for transmitting rotation of the drive motor to a drive shaft; a lower unit that includes a propeller shaft in which the propeller is provided and a second transmission mechanism for transmitting rotation of the drive shaft to the propeller shaft; the drive shaft that extends in a vertical direction from the upper unit to the lower unit; a connecting mechanism that connects the lower unit to the upper unit so that the lower unit is pivotable about an axis of the drive shaft; a steering motor provided in the upper unit and serving as a power source for pivoting the lower unit relative to the upper unit; and a third transmission mechanism provided between the upper unit and the lower unit and pivoting the lower unit relative to the upper unit by transmitting rotation of the steering motor to the lower unit. In the outboard motor of the embodiment, the drive shaft is disposed in front of an output shaft of the drive motor and the steering motor is disposed below the drive motor and behind the drive shaft.

[0022] In the outboard motor of the embodiment, the drive shaft is disposed in front of the output shaft of the drive motor. As the connecting mechanism is a mechanism that connects the lower unit to the upper unit so that the lower unit is pivotable about the axis of the drive shaft, an arrangement of the connecting mechanism can be determined along with an arrangement of the drive shaft. Therefore, by disposing the drive shaft in front of the output shaft of the drive motor, it is possible to dispose the connecting mechanism in front of the output shaft of the drive motor. By disposing the drive shaft and the connecting mechanism in front of the output shaft of the drive motor, a space can be made below the drive motor and behind the drive shaft and it is possible to dispose the steering motor in the space.

[0023] By disposing the drive shaft and the connecting mechanism in front of the output shaft of the drive motor and disposing the steering motor in the space below the drive motor and behind the drive shaft, a distance between the steering motor and the drive motor can be reduced, a distance between the steering motor and the drive shaft can be reduced, and a distance between the steering motor and the connecting mechanism can be reduced. As such, in the outboard motor of the embodiment, the steering motor can be disposed close to each of the drive motor, the drive shaft, and the connecting mechanism, so that it is possible to reduce a size of the outboard motor having a configuration in which the steering motor pivots the lower unit relative to the upper unit about the drive shaft.

Example

[0024] An outboard motor according to an example of the present invention will be described with reference to FIGS. 1 to 6. In the description of the example, directions of up (Ud), down (Dd), front (Fd), back (Bd), left (Ld), and right (Rd) follow arrows drawn at the lower left in each drawing.

Basic Configuration of Outboard Motor

[0025] FIG. 1 illustrates an outboard motor 1 according to the example of the present invention as viewed from the left. FIG. 2 illustrates the outboard motor 1 as viewed from behind. FIG. 3 illustrates a cross section of the outboard motor 1 cut along a line A-A in FIG. 2 as viewed from the left. FIG. 4 illustrates an enlarged view of a portion including a speed reducer 12, a connecting mechanism 40, a steering motor 45, and a worm gear mechanism 51 of the outboard motor in FIG. 3.

[0026] The outboard motor 1 is a device for propelling a boat, and as illustrated in FIG. 1, is mounted on a transom 120 of the boat. As illustrated in FIG. 3, the outboard motor 1 includes an upper unit 2 including a drive motor 3, an inverter 6, and the speed reducer 12, and a lower unit 21 including a propeller 22, a propeller shaft 23, and a rotation transmission mechanism 24. The lower unit 21 is disposed below the upper unit 2 and is connected to the upper unit 2. The outboard motor 1 also includes a drive shaft 31 that extends in a vertical direction from the upper unit 2 to the lower unit 21.

[0027] The drive motor 3 is a power source that rotates the propeller 22 and is, for example, an AC motor. The drive motor 3 includes a rotor, a stator, and an output shaft 4 that outputs rotation of the rotor. The drive motor 3 is provided with a motor case 5. The output shaft 4 excluding an end from which output is taken out, the rotor, and the stator are accommodated in the motor case 5. The drive motor 3 is disposed in an upper part of the outboard motor 1. When the outboard motor 1 is mounted on a boat, the drive motor 3 is positioned above the water surface. The drive motor 3 is disposed so that an extension direction of the output shaft 4 is the vertical direction.

[0028] The inverter 6 is a device that controls driving of the drive motor 3. The inverter 6 includes an inverter body 7 including a circuit for controlling the driving of the drive motor 3 and the like, and an inverter case 8 that accommodates the inverter body 7. The inverter 6 is disposed above the drive motor 3. The inverter 6 is mounted on the drive motor 3 via an inverter mounting member 10.

[0029] The speed reducer 12 is a device that reduces rotation of the output shaft 4 of the drive motor 3 and transmits the rotation to the drive shaft 31. The speed reducer 12 is disposed below the drive motor 3. As illustrated in FIG. 4, the speed reducer 12 includes a drive gear 13 and a driven gear 14. The drive gear 13 is coupled to a lower end of the output shaft 4 of the drive motor 3 and rotates integrally with the output shaft 4. The driven gear 14 is disposed in front of the drive gear 13. The driven gear 14 is coupled to an upper end of the drive shaft 31. The driven gear 14 meshes with the drive gear 13. A gear ratio between the drive gear 13 and the driven gear 14 (the number of teeth of the driven gear 14/the number of teeth of the drive gear 13) is greater than 1. The speed reducer 12 is a specific example of a first transmission mechanism.

[0030] A middle case 15 is provided in the upper unit 2 of the outboard motor 1. The middle case 15 is disposed below the drive motor 3 and is attached to the drive motor 3. The middle case 15 accommodates the speed reducer 12, an upper part of the drive shaft 31, the steering motor 45 described later, and the worm gear mechanism 51 described later. Although detailed illustration is omitted, the middle case 15 is divided into an upper case portion that accommodates the speed reducer 12 and a lower case portion that accommodates the steering motor 45 and the worm gear mechanism 51, and is formed by connecting the upper case portion to the lower case portion with a fastening member such as a bolt.

[0031] As illustrated in FIG. 3, the propeller shaft 23 is disposed in a lower part of the outboard motor 1. When the outboard motor 1 is mounted on a boat, the propeller shaft 23 is positioned below the water surface. The propeller shaft 23 extends in a front-rear direction. The propeller 22 is coupled to a rear part of the propeller shaft 23 and rotates integrally with the propeller shaft 23.

[0032] The rotation transmission mechanism 24 is a mechanism that transmits rotation of the drive shaft 31 to the propeller shaft 23. The rotation transmission mechanism 24 includes two bevel gears 25 and 26 that mesh with each other. One bevel gear 25 is coupled to a lower end of the drive shaft 31 and rotates integrally with the drive shaft 31. The other bevel gear 26 is coupled to a front end of the propeller shaft 23 and the propeller shaft 23 rotates integrally with the bevel gear 26. The rotation transmission mechanism 24 is a specific example of a second transmission mechanism.

[0033] A lower case 27 is provided in the lower unit 21 of the outboard motor 1. The rotation transmission mechanism 24 and a front part of the propeller shaft 23 are accommodated in the lower case 27. An anti-cavitation plate 28 is provided in a portion of the lower case 27 positioned above the propeller 22. A steering case 29 is provided in an uppermost part of the lower case 27.

[0034] The drive shaft 31 is a shaft that transmits rotation of the drive motor 3 after speed reduction by the speed reducer 12 to the propeller shaft 23. As described above, the driven gear 14 of the speed reducer 12 is coupled to the upper end of the drive shaft 31 and the drive shaft 31 rotates integrally with the driven gear 14. The bevel gear 25 of the rotation transmission mechanism 24 is coupled to the lower end of the drive shaft 31. The drive shaft 31 is disposed in front of the output shaft 4 of the drive motor 3. In the speed reducer 12, the drive gear 13 is coupled to the output shaft 4 of the drive motor 3, and the driven gear 14 disposed in front of the drive gear 13 is coupled to the drive shaft 31. As a result, the rotation of the output shaft 4 of the drive motor 3 is transmitted to the drive shaft 31 disposed in front of the output shaft 4 of the drive motor 3.

[0035] By control of the inverter 6, the drive motor 3 is driven and the output shaft 4 is rotated. The rotation of the output shaft 4 is transmitted to the drive shaft 31 while the speed is reduced by the speed reducer 12, thereby causing the drive shaft 31 to rotate. The rotation of the drive shaft 31 is transmitted to the propeller shaft 23 by the rotation transmission mechanism 24, thereby causing the propeller shaft 23 and the propeller 22 to rotate. The rotation of the propeller 22 generates thrust for the boat.

[0036] The outboard motor 1 also includes a mounting mechanism 33 for mounting the outboard motor 1 to a boat. The mounting mechanism 33 is disposed in front of the upper unit 2. The mounting mechanism 33 includes a pair of left and right clamp brackets 34 that secure the upper unit 2 to the transom 120 of the boat, and a mount bracket 35 that connects the clamp brackets 34 to the upper unit 2. A front part of the mount bracket 35 is disposed between the pair of clamp brackets 34 and is coupled to the pair of clamp brackets 34 via a tilt shaft 39. An upper mount portion 36 that supports an upper part of the upper unit 2 is provided in an upper rear part of the mount bracket 35. The upper mount portion 36 supports a portion of the upper part of the upper unit 2 positioned between the drive motor 3 and the inverter 6. A lower mount portion 37 that supports a lower part of the upper unit 2 is provided in a lower rear part of the mount bracket 35. The lower mount portion 37 supports a portion of the lower part of the upper unit 2 disposed above a portion at which the driven gear 14 of the speed reducer 12 is disposed. The mount bracket 35 can pivot vertically about an axis of the tilt shaft 39 relative to the clamp bracket 34. Accordingly, the outboard motor 1 can be pivoted (tilted up, tilted down) in the vertical direction relative to the boat. Unlike a typical swivel bracket, the mount bracket 35 does not have a structure for pivoting the outboard motor in a left-right direction. As described later, the outboard motor 1 has a function of pivoting the lower unit 21 in the left-right direction relative to the upper unit 2, so that even when a structure for pivoting the outboard motor 1 in the left-right direction is not provided in the mount bracket 35, the direction of the propeller 22 can be changed in the left-right direction and the boat can be steered.

Configuration Regarding Pivoting of Lower Unit

[0037] FIG. 5A illustrates the upper unit 2 separated from the lower unit 21 in the outboard motor 1 in FIG. 4. FIG. 5B illustrates the lower unit 21 separated from the upper unit 2 in the outboard motor 1 in FIG. 4. FIG. 6 illustrates the middle case 15 of the outboard motor 1 cut along a line B-B in FIG. 4 as well as the steering motor 45 and worm gear mechanism 51 disposed in the middle case 15 as viewed from above.

[0038] The outboard motor 1 has a function of steering the boat by pivoting the lower unit 21 in the left-right direction relative to the upper unit 2. Regarding the function, the outboard motor 1 is provided with the connecting mechanism 40, the steering motor 45, and the worm gear mechanism 51 as illustrated in FIGS. 4, 5A, 5B, and 6.

[0039] The connecting mechanism 40 connects the lower unit 21 to the upper unit 2 so that the lower unit 21 is pivotable about an axis K of the drive shaft 31. As illustrated in FIG. 4, the connecting mechanism 40 includes a first shaft portion 41 provided in an upper part of the lower unit 21, a second shaft portion 42 provided in the lower part of the upper unit 2, and a bearing 43, and is formed by connecting the first shaft portion 41 to the second shaft portion 42 via the bearing 43 so that the first shaft portion 41 is pivotable. More specifically, as illustrated in FIG. 5B, the steering case 29 is attached to an uppermost part of the lower case 27 provided in the lower unit 21 to cover an entire upper surface of the lower case 27. The first shaft portion 41 is provided in the steering case 29. The first shaft portion 41 is formed in a cylindrical shape having an axis coaxial with the axis K of the drive shaft 31, and extends upward from an upper surface of the steering case 29. The second shaft portion 42 is provided in a lower part of the middle case 15 positioned at the lower part of the upper unit 2 as illustrated in FIG. 5A. The second shaft portion 42 is formed in a cylindrical shape having an axis coaxial with the axis K of the drive shaft 31. An inner diameter of the second shaft portion 42 is larger than an outer diameter of the first shaft portion 41. As illustrated in FIG. 4, the first shaft portion 41 is inserted inside the second shaft portion 42 from below the second shaft portion 42. The bearing 43 is provided between an inner circumferential surface of the second shaft portion 42 and an outer circumferential surface of the first shaft portion 41. The first shaft portion 41 is coupled to the second shaft portion 42 so that the first shaft portion 41 is pivotable about the axis K of the drive shaft 31 relative to the second shaft portion 42, and is also coupled to the second shaft portion 42 so that the first shaft portion 41 does not shift in position in the vertical direction relative to the second shaft portion 42. The drive shaft 31 is inserted inside the first shaft portion 41 with a gap therebetween. The drive shaft 31 can rotate relative to the first shaft portion 41.

[0040] The steering motor 45 is a power source that pivots the lower unit 21 relative to the upper unit 2, and is, for example, a DC or AC motor. As illustrated in FIG. 5A, the steering motor 45 is provided in the upper unit 2 and disposed in the middle case 15. As illustrated in FIG. 4, the steering motor 45 is disposed below the drive motor 3 and behind the drive shaft 31. When the outboard motor 1 is viewed from above, at least a part of the steering motor 45 overlaps with the drive motor 3. The steering motor 45 is disposed behind the worm gear mechanism 51 and behind a worm wheel 53 and a worm 52. The steering motor 45 includes a rotor, a stator, and an output shaft 46 that outputs rotation of the rotor. As illustrated in FIG. 6, the steering motor 45 is disposed so that an axis L of the output shaft 46 is disposed on a plane perpendicular to the axis K of the drive shaft 31. The steering motor 45 is disposed so that an extension direction of the output shaft 46 is the left-right direction of the outboard motor 1. The steering motor 45 is mounted on a steering motor mounting portion 47, and the steering motor mounting portion 47 is fixed in the middle case 15.

[0041] The worm gear mechanism 51 is a mechanism that transmits rotation of the steering motor 45 to the lower unit 21 and pivots the lower unit 21 relative to the upper unit 2. As illustrated in FIG. 4, the worm gear mechanism 51 is provided between the upper unit 2 and the lower unit 21. The worm gear mechanism 51 is disposed below the speed reducer 12. The worm gear mechanism 51 includes the worm 52 that rotates along with the rotation of the steering motor 45, and the worm wheel 53 that meshes with the worm 52. The worm gear mechanism 51 is a specific example of a third transmission mechanism.

[0042] As illustrated in FIG. 5B, the worm wheel 53 is fixed to the steering case 29 provided in the lower unit 21. Specifically, the worm wheel 53 is fixed to an upper end of the first shaft portion 41 using a fastening member such as a bolt. As a result, the lower unit 21 pivots integrally with the worm wheel 53. The worm wheel 53 is disposed coaxially with the drive shaft 31 on an outer periphery of the drive shaft 31. As illustrated in FIG. 4, the worm wheel 53 is positioned in the middle case 15 below the driven gear 14 of the speed reducer 12.

[0043] As illustrated in FIG. 6, the worm 52 is disposed behind the worm wheel 53 so that an axis M of the worm 52 extends in the left-right direction of the outboard motor 1. The worm 52 is disposed between the steering motor 45 and the worm wheel 53. The worm 52 is disposed so that the axis M is parallel to the axis L of the output shaft 46 of the steering motor 45. The worm 52 is mounted on the steering motor mounting portion 47 together with the steering motor 45.

[0044] A gear 54 is provided in a left end of the output shaft 46 of the steering motor 45. The gear 54 is coupled to the output shaft 46 and rotates integrally with the output shaft 46. A gear 55 is provided in a left end of a shaft portion of the worm 52. The gear 55 is coupled to the shaft portion of the worm 52 and the worm 52 rotates integrally with the gear 55. The gear 54 and the gear 55 mesh with each other.

[0045] When the output shaft 46 of the steering motor 45 rotates by the driving of the steering motor 45, the rotation is transmitted to the worm 52 by the gears 54 and 55 and the worm 52 rotates. The rotation of the worm 52 is transmitted to the worm wheel 53 and the worm wheel 53 pivots. By the pivoting of the worm wheel 53, the lower unit 21 pivots left or right relative to the upper unit 2. By pivoting the lower unit 21 in the left-right direction as such, the direction of the propeller 22 can be changed in the left-right direction and the boat can be steered. By pivoting the lower unit 21 180 degrees left or right relative to the upper unit 2, the direction of the propeller 22 can be changed by 180 degrees. Accordingly, it is possible to move the boat backward without reversing the drive motor 3.

[0046] In the outboard motor 1 of the example of the present invention, the drive shaft 31 is disposed in front of the output shaft 4 of the drive motor 3 and the steering motor 45 is disposed below the drive motor 3 and behind the drive shaft 31, so that the steering motor 45 can be disposed close to each of the drive motor 3, the drive shaft 31 and the connecting mechanism 40. Therefore, it is possible to reduce the size of the outboard motor 1 having a configuration in which the lower unit 21 is pivoted relative to the upper unit 2 about the drive shaft 31 by the steering motor 45.

[0047] That is, in the outboard motor 1, the drive shaft 31 is disposed in front of the output shaft 4 of the drive motor 3. As the connecting mechanism 40 is a mechanism that connects the lower unit 21 to the upper unit 2 so that the lower unit 21 is pivotable about the axis K of the drive shaft 31, an arrangement of the connecting mechanism 40 can be determined along with an arrangement of the drive shaft 31. Therefore, by disposing the drive shaft 31 in front of the output shaft 4 of the drive motor 3, it is possible to dispose the connecting mechanism 40 in front of the output shaft 4 of the drive motor 3. By disposing the drive shaft 31 and the connecting mechanism 40 in front of the output shaft 4 of the drive motor 3, a space can be made below the drive motor 3 and behind the drive shaft 31 and it is possible to dispose the steering motor 45 in the space. By disposing the drive shaft 31 and the connecting mechanism 40 in front of the output shaft 4 of the drive motor 3 and disposing the steering motor 45 in the space below the drive motor 3 and behind the drive shaft 31, a distance between the steering motor 45 and the drive motor 3 can be reduced, a distance between the steering motor 45 and the drive shaft 31 can be reduced, and a distance between the steering motor 45 and the connecting mechanism 40 can be reduced. As such, in the outboard motor 1 of the example, the steering motor 45 can be disposed close to each of the drive motor 3, the drive shaft 31, and the connecting mechanism 40, so that it is possible to reduce a size of the outboard motor 1 having a configuration in which the steering motor 45 pivots the lower unit 21 relative to the upper unit 2 about the drive shaft 31.

[0048] In the outboard motor 1 of the example, the steering motor 45 is disposed so that the axis L of the output shaft 46 is disposed on the plane perpendicular to the axis K of the drive shaft 31. In the outboard motor 1 of the example, the steering motor 45 is disposed so that an extension direction of the output shaft 46 is the left-right direction of the outboard motor 1. Generally, most motors have a radial dimension smaller than an axial dimension. Therefore, a vertical dimension of a space in which the steering motor 45 is provided in the outboard motor 1 can be reduced by disposing the steering motor 45 so that the axis L of the output shaft 46 is disposed on the plane perpendicular to the axis K of the drive shaft 31, rather than disposing the steering motor 45 so that the axis L of the output shaft 46 is parallel to the axis K of the drive shaft 31. Therefore, the vertical dimension of the outboard motor 1 can be reduced.

[0049] In the worm gear mechanism 51 of the outboard motor 1 of the example, the worm wheel 53 is fixed to the lower unit 21 and is disposed coaxially with the drive shaft 31 on the outer periphery of the drive shaft 31, and the worm 52 extends in the left-right direction of the outboard motor 1 and is disposed behind the worm wheel 53. According to such configuration, the worm 52 can be disposed behind the worm wheel 53 and below the drive motor 3, and the worm 52 can be brought close to the steering motor 45 disposed below the drive motor 3. Accordingly, it is possible to accommodate the worm gear mechanism 51 and the steering motor 45 in a small space, facilitating miniaturization of the outboard motor 1.

[0050] In the outboard motor 1 of the example, the speed reducer 12 is disposed below the drive motor 3, and the worm gear mechanism 51 is disposed below the speed reducer 12. By such configuration, the distance between the drive motor 3 and the speed reducer 12 can be reduced and the distance between the speed reducer 12 and the worm gear mechanism 51 can be reduced, whereby it is possible to reduce the size of the outboard motor 1.

[0051] In the outboard motor 1 of the example, the speed reducer 12 includes the drive gear 13 coupled to the lower end of the output shaft 4 of the drive motor 3, and the driven gear 14 disposed in front of the drive gear 13, coupled to the upper end of the drive shaft 31, and meshing with the drive gear 13. By such configuration, the rotation of the drive motor 3 can be transmitted to the drive shaft 31 disposed front of the output shaft 4 of the drive motor 3.

[0052] In the outboard motor 1 of the example, the lower mount portion 37 of the mount bracket 35 supports a portion of the lower part of the upper unit 2 disposed above a portion at which the driven gear 14 of the speed reducer 12 is disposed. By such configuration, the distance between a support position of the lower mount portion 37 and the drive motor 3 can be reduced, allowing the drive motor 3 to be brought closer to the transom 120 of the boat. That is, the speed reducer 12 is disposed below the drive motor 3. Since the driven gear 14 of the speed reducer 12 is coupled to the drive shaft 31 disposed in front of the output shaft 4 of the drive motor 3, a part of the driven gear 14 protrudes forward from below the drive motor 3. The lower mount portion 37 supports a portion of the lower part of the upper unit 2 positioned above a portion of the driven gear 14 that protrudes forward from below the drive motor 3. Accordingly, the distance between the drive motor 3 and the transom 120 is reduced. By placing the drive motor 3 closer to the transom 120 as such, it is possible to facilitate tilting up of the outboard motor 1.

[0053] In the above example, the steering motor 45 is disposed behind the worm 52, but the steering motor 45 may be disposed below and behind the worm 52 or below the worm 52.

[0054] In the above example, the steering motor 45 is disposed so that the axis L of the output shaft 46 is in the left-right direction of the outboard motor 1, but the steering motor 45 may be disposed so that the axis L of the output shaft 46 is positioned on a plane perpendicular to the axis K of the drive shaft 31 and extends in a direction other than the left-right direction of the outboard motor 1.

[0055] In the above example, a DC or AC electric motor is used as the steering motor 45, but a hydraulic motor may be used as the steering motor 45.

[0056] The present invention can be modified as appropriate without departing from the spirit or the concept of the invention as can be read from the claims and the entire specification, and outboard motors incorporating such modifications are also included in the technical concept of the present invention.