outboard motor

Abstract

The present invention aims to reduce the size of an outboard motor having a configuration in which a lower unit is rotated relative to an upper unit around a drive shaft by a steering motor. [Solution] The outboard motor 1 comprises an upper unit 2 including a drive motor 3 and a reduction gear 12, a lower unit 21 including a propeller and propeller shaft, a drive shaft 31 extending from the upper unit 2 to the lower unit 21, a connecting mechanism 40 that rotatably connects the lower unit 21 to the upper unit 2, a steering motor 45 that is a power source that rotates the lower unit 21 relative to the upper unit 2, and a worm gear mechanism 51 that transmits the rotation of the steering motor 45 to the lower unit 21, and the drive shaft 31 is positioned forward of the output shaft 4 of the drive motor 3, and the steering motor 45 is positioned below the drive motor 3 and rearward of the drive shaft 31.

Description

[Technical Field]

[0001] The present invention relates to an outboard motor that can steer a boat by rotating a lower part of a body on which a propeller is mounted relative to an upper part of the body on which a power source that rotates the propeller is mounted. [Background technology]

[0002] There is known an outboard motor that can steer a boat by rotating a lower part of the body on which a propeller is mounted relative to an upper part of the body on which a power source for rotating the propeller is mounted (see, for example, Japanese Patent Application Laid-Open No. 2010-158926). Specifically, such an outboard motor includes an upper unit on which a power source for rotating the propeller is mounted, a lower unit on which a propeller shaft and a propeller are mounted, a drive shaft that transmits power from the power source to the propeller shaft, a connecting mechanism that connects the lower unit to the upper unit so that the lower unit can rotate about the axis of the drive shaft, a steering motor that is a power source that rotates the lower unit relative to the upper unit, and a power transmission mechanism that transmits power from the steering motor to the lower unit. The boat can be steered by rotating the lower unit relative to the upper unit when driven by the steering motor. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-158926 Summary of the Invention [Problem to be solved by the invention]

[0004] Japanese Patent Application Laid-Open Publication No. 2010-158926 describes efforts to reduce the size of outboard motors having the above-described configuration. However, there is currently a demand for further miniaturization of outboard motors having the above-described configuration.

[0005] The present invention has been made in consideration of the problems described above, and an object of the present invention is to reduce the size of an outboard motor having a configuration in which a steering motor rotates a lower unit relative to an upper unit about a drive shaft. [Means for solving the problem]

[0006] In order to solve the above problems, the present invention provides an outboard motor comprising: an upper unit including a drive motor that is a power source for rotating a propeller and a first transmission mechanism that transmits the rotation of the drive motor to a drive shaft; a lower unit including a propeller shaft on which a propeller is mounted and a second transmission mechanism that transmits the rotation of the drive shaft to the propeller shaft; the drive shaft extending in the vertical direction from the upper unit to the lower unit; a connecting mechanism that connects the lower unit to the upper unit rotatably about the axis of the drive shaft; a steering motor that is provided in the upper unit and is a power source for rotating the lower unit relative to the upper unit; and a third transmission mechanism that is provided between the upper unit and the lower unit and transmits the rotation of the steering motor to the lower unit to rotate the lower unit relative to the upper unit, wherein the drive shaft is located forward of an output shaft of the drive motor, and the steering motor is located below the drive motor and rearward of the drive shaft. [Effects of the Invention]

[0007] According to the present invention, it is possible to reduce the size of an outboard motor having a configuration in which a lower unit is rotated relative to an upper unit about a drive shaft by a steering motor. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is an explanatory diagram showing an outboard motor according to an embodiment of the present invention as viewed from the left. [Figure 2] 1 is an explanatory diagram showing an outboard motor according to an embodiment of the present invention as viewed from the rear. FIG. [Figure 3] 3 is a cross-sectional view of the outboard motor taken along the line AA in FIG. 2 as viewed from the left. [Figure 4] 4 is an enlarged cross-sectional view of the outboard motor in FIG. 3, showing a portion where a reduction gear transmission, a connecting mechanism, a steering motor, and a worm gear mechanism are provided. [Figure 5] 5(A) is a cross-sectional view showing an upper unit of the outboard motor in FIG. 4, and FIG. 5(B) is a cross-sectional view showing a lower unit of the outboard motor in FIG. [Figure 6] 5 is a cross-sectional view taken along line BB in FIG. 4, showing the middle case of the outboard motor, and the steering motor and worm gear mechanism disposed within the middle case, as viewed from above. DETAILED DESCRIPTION OF THE INVENTION

[0009] An outboard motor according to an embodiment of the present invention includes an upper unit including a drive motor as a power source for rotating a propeller and a first transmission mechanism for transmitting the rotation of the drive motor to a drive shaft, a lower unit including a propeller shaft on which the propeller is mounted and a second transmission mechanism for transmitting the rotation of the drive shaft to the propeller shaft, a drive shaft extending vertically from the upper unit to the lower unit, a connecting mechanism for connecting the lower unit to the upper unit so that the lower unit can rotate about the axis of the drive shaft, a steering motor provided in the upper unit as a power source for rotating the lower unit relative to the upper unit, and a third transmission mechanism provided between the upper and lower units for transmitting the rotation of the steering motor to the lower unit to rotate the lower unit relative to the upper unit. In the outboard motor according to this embodiment, the drive shaft is located forward of the output shaft of the drive motor, and the steering motor is located below the drive motor and rearward of the drive shaft.

[0010] In the outboard motor of this embodiment, the drive shaft is positioned forward of the drive motor output shaft. The connecting mechanism connects the lower unit to the upper unit so that the lower unit can rotate about the axis of the drive shaft, and therefore the position of the connecting mechanism can be determined to match the position of the drive shaft. Therefore, by positioning the drive shaft forward of the drive motor output shaft, the connecting mechanism can be positioned forward of the drive motor output shaft. Furthermore, by positioning the drive shaft and connecting mechanism forward of the drive motor output shaft, a space can be created below the drive motor and behind the drive shaft, and a steering motor can be positioned within that space.

[0011] By locating the drive shaft and coupling mechanism forward of the drive motor output shaft and locating the steering motor in the space below the drive motor and to the rear of the drive shaft, the distance between the steering motor and the drive motor can be reduced, and at the same time, the distance between the steering motor and the drive shaft can be reduced, and the distance between the steering motor and the coupling mechanism can also be reduced. In this way, with the outboard motor of this embodiment, the steering motor can be located close to each of the drive motor, drive shaft and coupling mechanism, so that an outboard motor configured to rotate the lower unit about the drive shaft relative to the upper unit by using the steering motor can be made smaller. [Example]

[0012] An outboard motor according to an embodiment of the present invention will be described with reference to Figures 1 to 6. In describing the embodiment, when directions such as up (Ud), down (Dd), front (Fd), rear (Bd), left (Ld), and right (Rd) are mentioned, they will be indicated by arrows drawn at the bottom left of each figure.

[0013] (Basic configuration of outboard motor) Fig. 1 shows an outboard motor 1 according to an embodiment of the present invention as seen from the left. Fig. 2 shows the outboard motor 1 as seen from the rear. Fig. 3 shows a cross section of the outboard motor 1 taken along line AA in Fig. 2 as seen from the left. Fig. 4 shows an enlarged view of the portion of the outboard motor in Fig. 3 where the reduction gear 12, connecting mechanism 40, steering motor 45, and worm gear mechanism 51 are provided.

[0014] The outboard motor 1 is a device for propelling a boat, and is mounted on the transom 120 of the boat, as shown in Fig. 1. As shown in Fig. 3, the outboard motor 1 includes an upper unit 2 that includes a drive motor 3, an inverter 6, and a reduction gear 12, and a lower unit 21 that includes a propeller 22, a propeller shaft 23, and a rotation transmission mechanism 24. The lower unit 21 is disposed below and connected to the upper unit 2. The outboard motor 1 also includes a drive shaft 31 that extends vertically from the upper unit 2 to the lower unit 21.

[0015] 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 the rotation of the rotor. The drive motor 3 also includes a motor case 5. The rotor, stator, and the rest of the output shaft 4, excluding the end that extracts power, are housed in the motor case 5. The drive motor 3 is disposed on top of the outboard motor 1. When the outboard motor 1 is mounted on a boat, the drive motor 3 is located above the water surface. The drive motor 3 is disposed so that the extension direction of the output shaft 4 is vertical.

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

[0017] The reduction gear 12 is a device that reduces the rotation of the output shaft 4 of the drive motor 3 and transmits it to the drive shaft 31. The reduction gear 12 is arranged below the drive motor 3. As shown in FIG. 4, the reduction gear 12 includes a drive gear 13 and a driven gear 14. The drive gear 13 is connected to the 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 arranged in front of the drive gear 13. The driven gear 14 is also connected to the upper end of the drive shaft 31. The driven gear 14 is also meshed with the drive gear 13. The gear ratio between the drive gear 13 and the driven gear 14 (number of teeth of the driven gear 14 / number of teeth of the drive gear 13) is greater than 1. The reduction gear 12 is a specific example of a "first transmission mechanism."

[0018] Additionally, the upper unit 2 of the outboard motor 1 is provided with a middle case 15. 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 reduction gear 12, the upper portion of the drive shaft 31, a steering motor 45 (described later), and a worm gear mechanism 51 (described later). Although not shown in detail, the middle case 15 is divided into an upper case portion that accommodates the reduction gear 12 and a lower case portion that accommodates the steering motor 45 and the worm gear mechanism 51, and the upper and lower case portions are joined together by joining members such as bolts.

[0019] As shown in Figure 3, the propeller shaft 23 is disposed at the bottom of the outboard motor 1. When the outboard motor 1 is mounted on a boat, the propeller shaft 23 is located below the water surface. The propeller shaft 23 extends in the fore-and-aft direction. The propeller 22 is coupled to the rear of the propeller shaft 23 and rotates integrally with the propeller shaft 23.

[0020] The rotation transmission mechanism 24 is a mechanism that transmits the rotation of the drive shaft 31 to the propeller shaft 23. The rotation transmission mechanism 24 includes two bevel gears 25, 26 that mesh with each other. One bevel gear 25 is coupled to the lower end of the drive shaft 31 and rotates integrally with the drive shaft 31. The other bevel gear 26 is coupled to the 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."

[0021] The lower unit 21 of the outboard motor 1 is provided with a lower case 27. The rotation transmission mechanism 24 and the front part of the propeller shaft 23 are housed in the lower case 27. An anti-cavitation plate 28 is provided in a portion of the lower case 27 located above the propeller 22. A steering case 29 is provided at the top of the lower case 27.

[0022] The drive shaft 31 is a shaft that transmits the rotation of the drive motor 3 after being reduced in speed by the reduction gear 12 to the propeller shaft 23. As described above, the driven gear 14 of the reduction gear 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 also disposed forward of the output shaft 4 of the drive motor 3. In the reduction gear 12, the drive gear 13 is coupled to the output shaft 4 of the drive motor 3, and the driven gear 14, which is disposed forward 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, which is disposed forward of the output shaft 4 of the drive motor 3.

[0023] The drive motor 3 is driven by 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 31 while being reduced in speed by the reduction gear 12, 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, causing the propeller shaft 23 and the propeller 22 to rotate. The rotation of the propeller 22 generates a propulsive force for the vessel.

[0024] The outboard motor 1 also includes a mounting mechanism 33 for mounting the outboard motor 1 to the boat. The mounting mechanism 33 is located 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. The front portion of the mount bracket 35 is located between the pair of clamp brackets 34 and is connected to the pair of clamp brackets 34 via a tilt shaft 39. An upper mount 36 that supports the upper portion of the upper unit 2 is provided at the top of the rear portion of the mount bracket 35. The upper mount 36 supports a portion of the upper portion of the upper unit 2 that is located between the drive motor 3 and the inverter 6. A lower mount 37 that supports the lower portion of the upper unit 2 is provided at the bottom of the rear portion of the mount bracket 35. The lower mount 37 supports a portion of the lower portion of the upper unit 2 that is located above the portion where the driven gear 14 of the reduction gear 12 is located. Additionally, the mount bracket 35 can rotate vertically about the axis of the tilt shaft 39 relative to the clamp bracket 34. This allows the outboard motor 1 to be rotated (tilted up and down) vertically relative to the boat. Unlike a typical swivel bracket, the mount bracket 35 does not have a structure for rotating the outboard motor left and right. As will be described later, the outboard motor 1 has the function of rotating the lower unit 21 left and right relative to the upper unit 2. Therefore, even if the mount bracket 35 does not have a structure for rotating the outboard motor 1 left and right, the orientation of the propeller 22 left and right can be changed and the boat can be steered.

[0025] (Configuration regarding rotation of lower unit) Figure 5(A) shows the upper unit 2 separated from the lower unit 21 in the outboard motor 1 in Figure 4. Figure 5(B) shows the lower unit 21 separated from the upper unit 2 in the outboard motor 1 in Figure 4. Figure 6 shows the middle case 15 of the outboard motor 1 cut along the cutting line BB in Figure 4, as well as the steering motor 45 and worm gear mechanism 51 arranged inside the middle case 15, as viewed from above.

[0026] The outboard motor 1 has the function of steering the boat by rotating the lower unit 21 left and right relative to the upper unit 2. For this function, the outboard motor 1 is equipped with a connecting mechanism 40, a steering motor 45, and a worm gear mechanism 51, as shown in Figures 4, 5(A), 5(B), and 6.

[0027] The connecting mechanism 40 connects the lower unit 21 to the upper unit 2 so as to be rotatable about the axis K of the drive shaft 31. As shown in FIG. 4 , the connecting mechanism 40 includes a first shaft 41 provided on the upper part of the lower unit 21, a second shaft 42 provided on the lower part of the upper unit 2, and a bearing 43, and is formed by rotatably connecting the first shaft 41 to the second shaft 42 via the bearing 43. More specifically, as shown in FIG. 5(B) , a steering case 29 is attached to the top of the lower case 27 provided on the lower unit 21 so as to cover the entire upper surface of the lower case 27. The first shaft 41 is provided on this steering case 29. The first shaft 41 is formed in a cylindrical shape having an axis coaxial with the axis K of the drive shaft 31 and extends upward from the upper surface of the steering case 29. On the other hand, as shown in FIG. 5(A), the second shaft portion 42 is provided at the bottom of the middle case 15, which is located at the bottom of the upper unit 2. The second shaft portion 42 is formed in a cylindrical shape with an axis coaxial with the axis K of the drive shaft 31. The inner diameter of the second shaft portion 42 is larger than the outer diameter of the first shaft portion 41. As shown in FIG. 4, the first shaft portion 41 is inserted into the inside of the second shaft portion 42 from below. A bearing 43 is provided between the inner peripheral surface of the second shaft portion 42 and the outer peripheral surface of the first shaft portion 41. The first shaft portion 41 is coupled to the second shaft portion 42 so as to be rotatable about the axis K of the drive shaft 31 relative to the second shaft portion 42, and at the same time, is coupled to the second shaft portion 42 so as not to be displaced vertically relative to the second shaft portion 42. The drive shaft 31 is inserted inside the first shaft portion 41 with a space therebetween. The drive shaft 31 is rotatable relative to the first shaft portion 41 .

[0028] The steering motor 45 is a power source that rotates the lower unit 21 relative to the upper unit 2, and is, for example, a DC or AC electric motor. As shown in FIG. 5(A), the steering motor 45 is mounted on the upper unit 2 and disposed within the middle case 15. As shown in FIG. 4, the steering motor 45 is disposed below the drive motor 3 and rearward of the drive shaft 31. When the outboard motor 1 is viewed from above, at least a portion of the steering motor 45 overlaps with the drive motor 3. The steering motor 45 is disposed rearward of the worm gear mechanism 51 and rearward of the worm wheel 53 and the worm 52. The steering motor 45 includes a rotor, a stator, and an output shaft 46 that outputs the rotation of the rotor. As shown in FIG. 6, the steering motor 45 is disposed so that the axis L of the output shaft 46 is located on a plane perpendicular to the axis K of the drive shaft 31. The steering motor 45 is disposed so that the extension direction of the output shaft 46 is the left-right direction of the outboard motor 1. Further, the steering motor 45 is attached to a steering motor attachment portion 47 , and the steering motor attachment portion 47 is fixed inside the middle case 15 .

[0029] Worm gear mechanism 51 is a mechanism that transmits the rotation of steering motor 45 to lower unit 21 to rotate lower unit 21 relative to upper unit 2. As shown in FIG. 4, worm gear mechanism 51 is provided between upper unit 2 and lower unit 21. Worm gear mechanism 51 is also disposed below reduction gear 12. Worm gear mechanism 51 includes worm 52 that rotates with the rotation of steering motor 45, and worm wheel 53 that meshes with worm 52. Worm gear mechanism 51 is a specific example of a "third transmission mechanism."

[0030] As shown in FIG. 5(B), 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 the upper end of the first shaft portion 41 using a connecting member such as a bolt. This allows the lower unit 21 to rotate integrally with the worm wheel 53. The worm wheel 53 is also disposed coaxially with the drive shaft 31 on the outer circumferential side of the drive shaft 31. As shown in FIG. 4, the worm wheel 53 is located below the driven gear 14 of the reduction gear transmission 12 within the middle case 15.

[0031] 6, the worm 52 is disposed rearward of the worm wheel 53 so that its axis M 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 its axis M is parallel to the axis L of the output shaft 46 of the steering motor 45. The worm 52 is attached to the steering motor mounting portion 47 together with the steering motor 45.

[0032] A gear 54 is provided at the 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 at the left end of the 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 gears 54 and 55 mesh with each other.

[0033] When the steering motor 45 is driven to rotate the output shaft 46 of the steering motor 45, the rotation is transmitted to the worm 52 via gears 54 and 55, causing the worm 52 to rotate. The rotation of the worm 52 is then transmitted to the worm wheel 53, causing the worm wheel 53 to rotate. The rotation of the worm wheel 53 causes the lower unit 21 to rotate left or right relative to the upper unit 2. By rotating the lower unit 21 left or right in this way, the left-right direction of the propeller 22 can be changed, and the boat can be steered. Furthermore, by rotating the lower unit 21 180 degrees left or right relative to the upper unit 2, the direction of the propeller 22 can be changed 180 degrees. This allows the boat to move backward without rotating the drive motor 3 in the reverse direction.

[0034] In outboard motor 1 according to the embodiment of the present invention, drive shaft 31 is located forward of output shaft 4 of drive motor 3, and steering motor 45 is located below drive motor 3 and to the rear of drive shaft 31, so that steering motor 45 can be located close to drive motor 3, drive shaft 31, and connecting mechanism 40. This makes it possible to reduce the size of outboard motor 1, which has a configuration in which steering motor 45 rotates lower unit 21 about drive shaft 31 relative to upper unit 2.

[0035] That is, in the outboard motor 1, the drive shaft 31 is positioned forward of the output shaft 4 of the drive motor 3. The connecting mechanism 40 connects the lower unit 21 to the upper unit 2 so that the lower unit 21 can rotate about the axis K of the drive shaft 31, and therefore the position of the connecting mechanism 40 can be determined to match the position of the drive shaft 31. Therefore, by positioning the drive shaft 31 forward of the output shaft 4 of the drive motor 3, the connecting mechanism 40 can be positioned forward of the output shaft 4 of the drive motor 3. Furthermore, by positioning the drive shaft 31 and the connecting mechanism 40 forward of the output shaft 4 of the drive motor 3, a space can be created below the drive motor 3 and behind the drive shaft 31, and a steering motor 45 can be positioned within that space. By positioning the drive shaft 31 and the connecting mechanism 40 forward of the output shaft 4 of the drive motor 3 and by positioning the steering motor 45 in the space below the drive motor 3 and to the rear of the drive shaft 31, the distance between the steering motor 45 and the drive motor 3 can be reduced, and at the same time, the distance between the steering motor 45 and the drive shaft 31 can be reduced, and the distance between the steering motor 45 and the connecting mechanism 40 can also be reduced. In this way, with the outboard motor 1 of this embodiment, the steering motor 45 can be positioned close to the drive motor 3, the drive shaft 31 and the connecting mechanism 40, so that the outboard motor 1, which has a configuration in which the steering motor 45 rotates the lower unit 21 about the drive shaft 31 relative to the upper unit 2, can be made more compact.

[0036] Furthermore, in the outboard motor 1 of this embodiment, the steering motor 45 is disposed so that the axis L of its output shaft 46 is located on a plane perpendicular to the axis K of the drive shaft 31. Furthermore, in the outboard motor 1 of this embodiment, the steering motor 45 is disposed so that the extension direction of the output shaft 46 is the left-right direction of the outboard motor 1. Generally, the radial dimension of most motors is smaller than the axial dimension. Therefore, the vertical dimension of the space in the outboard motor 1 where the steering motor 45 is provided can be made smaller by disposing the steering motor 45 so that the axis L of the output shaft 46 is located on a 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 made smaller.

[0037] In the worm gear mechanism 51 of the outboard motor 1 of this embodiment, the worm wheel 53 is fixed to the lower unit 21 and is arranged coaxially with the drive shaft 31 on the outer periphery thereof, and the worm 52 extends in the left-right direction of the outboard motor 1 and is arranged rearward of the worm wheel 53. With this configuration, the worm 52 can be arranged rearward of the worm wheel 53 and below the drive motor 3, and the worm 52 can be brought close to the steering motor 45, which is arranged below the drive motor 3. This allows the worm gear mechanism 51 and the steering motor 45 to be accommodated in a small space, facilitating the downsizing of the outboard motor 1.

[0038] Furthermore, in the outboard motor 1 of this embodiment, the reduction gear 12 is disposed below the drive motor 3, and the worm gear mechanism 51 is disposed below the reduction gear 12. This configuration reduces the distance between the drive motor 3 and the reduction gear 12, and also reduces the distance between the reduction gear 12 and the worm gear mechanism 51, allowing the outboard motor 1 to be made more compact.

[0039] In the outboard motor 1 of this embodiment, the reduction gear 12 includes a drive gear 13 connected to the lower end of the output shaft 4 of the drive motor 3, and a driven gear 14 disposed in front of the drive gear 13, connected to the upper end of the drive shaft 31, and meshing with the drive gear 13. With this configuration, the rotation of the drive motor 3 can be transmitted to the drive shaft 31, which is disposed forward of the output shaft 4 of the drive motor 3.

[0040] In the outboard motor 1 of this embodiment, the lower mount portion 37 of the mount bracket 35 supports a portion of the lower part of the upper unit 2 that is located above the portion where the driven gear 14 of the reduction gear 12 is located. This configuration reduces the distance between the support position of the lower mount portion 37 and the drive motor 3, allowing the drive motor 3 to be closer to the transom 120 of the boat. That is, the reduction gear 12 is located below the drive motor 3. Furthermore, because the driven gear 14 of the reduction gear 12 is coupled to the drive shaft 31 that is located forward of the output shaft 4 of the drive motor 3, a portion 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 that is located above the portion of the driven gear 14 that protrudes forward from below the drive motor 3. This reduces the distance between the drive motor 3 and the transom 120. By moving the drive motor 3 closer to the transom 120 in this manner, it is possible to easily tilt up the outboard motor 1.

[0041] In the above embodiment, the steering motor 45 is disposed behind the worm 52, but the steering motor 45 may be disposed below the rear or below the worm 52.

[0042] Furthermore, in the above embodiment, the steering motor 45 is arranged so that the axis L of its output shaft 46 is aligned in the left-right direction of the outboard motor 1, but the steering motor 45 may also be arranged so that the axis L of its output shaft 46 is located 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.

[0043] Furthermore, in the above embodiment, a DC or AC electric motor is used as the steering motor 45, but a hydraulic motor may also be used as the steering motor 45.

[0044] 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 outboard motors incorporating such modifications are also included within the technical concept of the present invention. [Explanation of symbols]

[0045] 1 outboard motor 2 Upper unit 3 Drive motor 4 output shaft 12 Reduction gear (first transmission mechanism) 13 Drive gear 14 Driven gear 21 Lower unit 22 propeller 23 Propeller shaft 24 Rotation transmission device (second transmission mechanism) 31 Drive shaft 33 Mounting mechanism 34 Clamp bracket 35 Mounting bracket 36 Upper mount 37 Lower mount 40 Connection mechanism 45 Steering motor 46 Output shaft 51 Worm gear mechanism (third transmission mechanism) 52 Warm 53 Worm Wheel

Claims

1. an upper unit including a drive motor as a power source for rotating the propeller and a first transmission mechanism for transmitting the rotation of the drive motor to a drive shaft; a lower unit including a propeller shaft provided with a propeller and a second transmission mechanism that transmits rotation of the drive shaft to the propeller shaft; the drive shaft extending in the vertical direction from the upper unit to the lower unit; a connecting mechanism that connects the lower unit to the upper unit so as to be rotatable about the axis of the drive shaft; a steering motor provided in the upper unit and serving as a power source for rotating the lower unit relative to the upper unit; a third transmission mechanism provided between the upper unit and the lower unit, for transmitting rotation of the steering motor to the lower unit to rotate the lower unit relative to the upper unit, the drive shaft is disposed forward of the output shaft of the drive motor, and the steering motor is disposed below the drive motor and rearward of the drive shaft.

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

3. 2. An outboard motor according to claim 1, wherein the steering motor is disposed so that the extension direction of its output shaft coincides with the left-right direction of the outboard motor.

4. 4. An outboard motor according to claim 3, wherein the third transmission mechanism includes a worm that rotates with 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 the outer circumferential side of the drive shaft, and the worm extends in the left-right direction of the outboard motor and is disposed rearward of the worm wheel.

5. 2. 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 first transmission mechanism includes: a drive gear coupled to a lower end of an output shaft of the drive motor; 2. The outboard motor according to claim 1, further comprising a driven gear disposed forward of the drive gear, coupled to an upper end of the drive shaft, and meshing with the drive gear.

7. an attachment mechanism for attaching the upper unit to the vessel, the attachment mechanism including a clamp bracket for fixing the upper unit to the vessel, and a mount bracket connected to the clamp bracket, the mount bracket having an upper mount portion for supporting an upper portion of the upper unit and a lower mount portion for supporting a lower portion of the upper unit; the first transmission mechanism is disposed below the drive motor; 7. The outboard motor according to claim 6, wherein the lower mount supports a portion of the lower part of the upper unit that is located above a portion of the first transmission mechanism where the driven gear is disposed.

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