outboard motor

Abstract

Move the center of gravity of the outboard motor closer to the boat. [Solution] The outboard motor 1 comprises an outboard motor body 2 and an attachment mechanism 40 provided in front of the outboard motor body 2 for attaching the outboard motor body 2 to the boat; the outboard motor body 2 comprises a motor 3, a drive shaft 8, a reduction gear 9 that reduces the rotation of the motor 3 and transmits it to the drive shaft 8, a propeller shaft 13 equipped with a propeller 20, and a rotation transmission mechanism 14 that transmits the rotation of the drive shaft 8 to the propeller shaft 13; the reduction gear 9 is positioned so that the front part of the reduction gear 9 is located above the attachment mechanism 40 and the rear part of the reduction gear 9 is located above the motor 3.

Description

[Technical Field]

[0001] The present invention relates to an outboard motor equipped with a motor as a power source for rotating a propeller. [Background technology]

[0002] Japanese Patent Application Laid-Open Publication No. 2005-162055 (Patent Document 1) describes an outboard motor equipped with a motor (electric motor) as a power source for rotating a propeller. As shown in FIG. 1 of the publication, in this outboard motor, the motor is disposed so that the extension direction of the output shaft is in the vertical direction. A reduction gear is provided below the motor. The reduction gear includes two meshing reduction gears. One of these reduction gears, a drive gear, is connected to the lower end of the motor's output shaft, and the other, a driven gear, is connected to the upper end of a drive shaft. The drive shaft extends downward from the reduction gear, and the lower end of the drive shaft is connected via a bevel gear to a propeller shaft extending in the fore-and-aft direction.

[0003] The outboard motor also includes a bracket device having a clamp portion, a swivel portion, and the like. The swivel portion is connected to the clamp portion via a tilt shaft. The outboard motor is attached to the transom of the boat by the clamp portion. The outboard motor is supported by the swivel portion so that it can rotate left and right relative to the boat. The swivel portion can rotate up and down relative to the clamp portion, with the tilt shaft as the rotation axis. This allows the outboard motor to rotate up and down (tilt up and down) relative to the boat. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-162055 Summary of the Invention [Problem to be solved by the invention]

[0005] As can be seen from Figure 1 of the above publication, when the outboard motor is attached to the transom of a boat by the clamp, the swivel is located behind the transom, and the motor and reduction gear are located behind the swivel. As a result, the motor and reduction gear are located far behind the transom. Because both the motor and reduction gear are heavy, the distance between the motor and reduction gear and the transom results in the outboard motor's center of gravity being far behind the transom.

[0006] The force required to tilt up an outboard motor increases as the center of gravity of the outboard motor moves further aft from the transom. If the outboard motor is designed to be tilted manually, the increased force required to tilt up the outboard motor increases the burden on the user. Furthermore, if the outboard motor is designed to be tilted up using a hydraulic or electric actuator, the increased force required to tilt up the outboard motor requires a high-output actuator, which may increase the manufacturing costs of the outboard motor.

[0007] The present invention has been made in consideration of the above-mentioned problems, and an object of the present invention is to provide an outboard motor that can bring the center of gravity of the outboard motor closer to the boat. [Means for solving the problem]

[0008] In order to solve the above problems, the present invention provides an outboard motor comprising an outboard motor main body and an attachment mechanism provided in front of the outboard motor main body for attaching the outboard motor main body to a boat, wherein the outboard motor main body comprises a motor, a drive shaft, a first transmission mechanism that transmits rotation of the motor to the drive shaft, a propeller shaft provided with a propeller, and a second transmission mechanism that transmits rotation of the drive shaft to the propeller shaft, and wherein the first transmission mechanism is arranged so that a front portion of the first transmission mechanism is located above the attachment mechanism and a rear portion of the first transmission mechanism is located above the motor. [Effects of the Invention]

[0009] According to the present invention, the center of gravity of the outboard motor can be brought closer to the boat. [Brief explanation of the drawings]

[0010] [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] FIG. 2 is an explanatory diagram showing the upper part of the outboard motor according to the embodiment of the present invention as viewed from behind. [Figure 3] 3 is a cross-sectional view of the outboard motor taken along the line III-III in FIG. 2 as viewed from the left. FIG. [Figure 4] FIG. 2 is an explanatory diagram showing the motor, upper case, middle case, lower case, and inverter, each of which is separated, in the outboard motor according to the embodiment of the present invention. [Figure 5] 4 is a cross-sectional view of the outboard motor taken along line VV in FIG. 3 as viewed from above. [Figure 6] 6 is a cross-sectional view of the outboard motor taken along line VI-VI in FIG. 3 as viewed from above. DETAILED DESCRIPTION OF THE INVENTION

[0011] An outboard motor according to an embodiment of the present invention includes an outboard motor main body and a mounting mechanism provided at the front of the outboard motor main body for mounting the outboard motor main body to a boat. The outboard motor main body also includes a motor, a drive shaft, a first transmission mechanism for transmitting rotation of the motor to the drive shaft, a propeller shaft provided with a propeller, and a second transmission mechanism for transmitting rotation of the drive shaft to the propeller shaft. The first transmission mechanism is positioned so that its front portion is located above the mounting mechanism and its rear portion is located above the motor.

[0012] In the outboard motor of this embodiment, the mounting mechanism is provided at the front of the outboard motor body, and the outboard motor body is equipped with a motor. As a result of this configuration, the mounting mechanism and the motor are aligned in the fore-and-aft direction, with the mounting mechanism located at the front and the motor located at the rear. The first transmission mechanism is disposed above the mounting mechanism and motor, which are aligned in the fore-and-aft direction in this manner. As a result, the front part of the first transmission mechanism is located above the mounting mechanism, and the rear part of the first transmission mechanism is located above the motor.

[0013] In this configuration, when the outboard motor is viewed from above, the first transmission mechanism is positioned so that its front portion overlaps the mounting mechanism. By positioning the first transmission mechanism so that its front portion overlaps the mounting mechanism in this way, the first transmission mechanism can be shifted forward so that it is closer to the boat to which the outboard motor is attached, compared to when the entire first transmission mechanism is positioned behind the mounting mechanism, and therefore the distance in the fore-and-aft direction between the first transmission mechanism and the transom of the boat can be shortened.

[0014] The first transmission mechanism transmits rotation of the motor to the drive shaft, and the output shaft of the motor is connected to the first transmission mechanism directly or via another shaft. Therefore, the location of the motor must be determined taking into consideration the location of the first transmission mechanism. However, in the outboard motor of this embodiment, the location of the first transmission mechanism can be shifted forward so as to be closer to the boat, and therefore the location of the motor can be shifted forward so as to be closer to the boat. This shortens the fore-and-aft distance between the motor and the transom of the boat.

[0015] As described above, with the outboard motor of this embodiment, the motor and first transmission mechanism, which are heavy objects, can be located closer to the boat, and therefore the center of gravity of the outboard motor can be located closer to the boat. By locating the center of gravity of the outboard motor closer to the boat, the force required to tilt up the outboard motor can be reduced. Therefore, if the outboard motor is designed to be tilted up manually, the burden on the user who tilts up the outboard motor can be reduced. Furthermore, if the outboard motor is designed to be tilted up using a hydraulic or electric actuator, a low-output actuator can be used as the tilt-up actuator, reducing the manufacturing cost of the outboard motor.

[0016] In the outboard motor of this embodiment, the first transmission mechanism is positioned so that its front portion overlaps the mounting mechanism when viewed from above, and by positioning the first transmission mechanism so that its front portion overlaps the mounting mechanism in this manner, the motor can be shifted forward to be closer to the mounting mechanism, thereby reducing the longitudinal dimension of the outboard motor. [Example]

[0017] An outboard motor according to an embodiment of the present invention will be described with reference to the drawings. In describing the embodiment, the directions of up (Ud), down (Dd), front (Fd), rear (Bd), left (Ld), and right (Rd) will be indicated by arrows drawn at the bottom left of each drawing.

[0018] FIG. 1 shows an outboard motor 1 according to an embodiment of the present invention, as viewed from the left. FIG. 2 shows the upper part of the outboard motor 1 as viewed from the rear. FIG. 3 shows a cross section of the outboard motor 1 taken along section line III-III in FIG. 2, as viewed from the left. FIG. 4 shows the motor 3, upper case 25, middle case 26, lower case 27, and inverter 35, each separated. FIG. 5 shows a cross section of the outboard motor 1 taken along section line VV in FIG. 3, as viewed from above. FIG. 6 shows a cross section of the outboard motor 1 taken along section line VI-VI in FIG. 3, as viewed from above.

[0019] (Overall configuration of outboard motor) An outboard motor 1 is a device for propelling a boat. As shown in Figure 1, the outboard motor 1 is mounted on the transom 101 of the boat. The outboard motor 1 includes an outboard motor main body 2 and a mounting mechanism 40 for mounting the outboard motor main body 2 to the boat.

[0020] As shown in Fig. 3, the outboard motor body 2 includes a motor 3, which is a power source that rotates a propeller 20, a drive shaft 8 that transmits the power of the motor 3 to the propeller 20, a reduction gear 9 that reduces the rotation of an output shaft 4 of the motor 3 and transmits it to the drive shaft 8, a propeller shaft 13, a rotation transmission mechanism 14 that transmits the rotation of the drive shaft 8 to the propeller shaft 13, and a propeller 20 that converts the power of the motor 3 into propulsion power for the boat. The outboard motor body 2 also includes a shift device 31 that controls switching of the rotation direction of the propeller 20. The outboard motor body 2 also includes an inverter 35 that controls the drive of the motor 3. The reduction gear 9 is a specific example of a "first transmission mechanism," and the rotation transmission mechanism 14 is a specific example of a "second transmission mechanism."

[0021] The motor 3 and reduction gear 9 are disposed in the upper part of the outboard motor body 2. When the outboard motor 1 is attached to a boat, the motor 3 and reduction gear 9 are located above the water surface. Meanwhile, the rotation transmission mechanism 14, propeller shaft 13, and propeller 20 are disposed in the lower part of the outboard motor body 2. When the outboard motor 1 is attached to a boat, the rotation transmission mechanism 14, propeller shaft 13, and propeller 20 are located below the water surface.

[0022] The mounting mechanism 40 is disposed at the front of the upper part of the outboard motor body 2. As shown in Fig. 1, the mounting mechanism 40 includes a pair of left and right clamp brackets 41 that secure the outboard motor body 2 to the transom 101 of the boat, a pilot shaft 42 that serves as an axis for rotation of the outboard motor body 2 in the lateral direction, a swivel bracket 43 that is connected to the clamp brackets 41 and that supports the pilot shaft 42 so that it can rotate, a pair of left and right upper mounts 47 that connect the upper end of the pilot shaft 42 to the outboard motor body 2, and a pair of left and right lower mounts 49 that connect the lower end of the pilot shaft 42 to the outboard motor body 2.

[0023] (Details of each part of the outboard motor) As shown in Fig. 3, the motor 3 in the outboard motor body 2 includes an output shaft 4, which is a power output shaft, a rotor 5 mounted on the outer periphery of the output shaft 4, a stator 6 mounted on the outer periphery of the rotor 5, and a generally cylindrical motor case 7. The motor case 7 houses the output shaft 4 except for one end, the rotor 5, and the stator 6. The motor 3 is arranged so that the extension direction of the output shaft 4 is vertical. The motor 3 is also arranged so that the end of the output shaft 4 from which power is taken out faces upward.

[0024] As shown in Figure 3, the reduction gear 9 is disposed above the motor 3. Specifically, the reduction gear 9 is disposed so that the front portion of the reduction gear 9 is located above the swivel bracket 43 and the rear portion of the reduction gear 9 is located above the motor 3. When viewed from above the outboard motor body 2, the reduction gear 9 is disposed so that its front portion overlaps the swivel bracket 43. In addition, the front portion of the reduction gear 9 is located above the pilot shaft 42. In addition, the reduction gear 9 is located above the upper mount 47.

[0025] 3 and 5, the reduction gear 9 includes a drive sprocket 10 that inputs the rotation of the output shaft 4 of the motor 3 to the reduction gear 9, a driven sprocket 11 that reduces the rotation input to the reduction gear 9 and outputs it from the reduction gear 9 to the drive shaft 8, and a silent chain 12 that is stretched across the drive sprocket 10 and the driven sprocket 11. The gear ratio of the drive sprocket 10 and the driven sprocket 11 (number of teeth of the driven sprocket 11 / number of teeth of the drive sprocket 10) is greater than 1. The drive sprocket 10 is a specific example of a "first rotation transmitting element," and the driven sprocket 11 is a specific example of a "second rotation transmitting element."

[0026] The drive sprocket 10 is located above the motor 3 and is arranged coaxially with the output shaft 4 of the motor 3. The lower end of the boss of the drive sprocket 10 is connected (for example, spline connected) to the upper end of the output shaft 4 of the motor 3, so that the drive sprocket 10 rotates integrally with the output shaft 4.

[0027] The driven sprocket 11 is disposed in front of the drive sprocket 10. The driven sprocket 11 is disposed above the drive shaft 8 and coaxially therewith. A portion of the driven sprocket 11 is located above the swivel bracket 43. The lower end of the boss of the driven sprocket 11 is connected (for example, spline-connected) to the upper end of the drive shaft 8.

[0028] The reduction gear 9 is housed in an upper case 25. As can be seen from Figures 1 and 4, the upper case 25 is disposed above the motor 3 and is attached to the motor case 7 using connecting members such as bolts. The upper case is a specific example of a "case."

[0029] The drive shaft 8 extends in the vertical direction from the reduction gear 9 to the rotation transmission mechanism 14. The drive shaft 8 is disposed between the swivel bracket 43 and the motor 3, which are aligned in the longitudinal direction. As described above, the upper end of the drive shaft 8 is coupled to the lower end of the boss of the driven sprocket 11, and the drive shaft 8 rotates integrally with the driven sprocket 11.

[0030] 1 and 4, the outboard motor 1 has a middle case 26 disposed below the motor 3, and a lower case 27 disposed below the middle case 26. The middle case 26 is attached to the motor case 7 using fastening members such as bolts, and the lower case is attached to the middle case 26 using fastening members such as bolts. As shown in FIG. 3, the upper end portion of the drive shaft 8 is covered by the upper case 25. The upper portion of the drive shaft 8, below the upper end portion, is located in front of the motor 3 and passes outside the motor case 7. The vertically intermediate portion of the drive shaft 8 passes through the middle case 26. The lower portion of the drive shaft 8 passes through the lower case 27.

[0031] The rotation transmission mechanism 14 is housed in the lower case 27. The rotation transmission mechanism 14 includes a transmission gear 15, a forward gear 16, a reverse gear 17, a dog clutch 18, and a shift plunger 19. The transmission gear 15, the forward gear 16, and the reverse gear 17 are all bevel gears. The rotation axis of the transmission gear 15 extends in the vertical direction. The transmission gear 15 is coupled to the lower end of the drive shaft 8 and rotates integrally with the drive shaft 8. The rotation axes of the forward gear 16 and the reverse gear 17 extend in the front-to-rear direction. The forward gear 16 is disposed in front of the transmission gear 15, and the reverse gear 17 is disposed behind the transmission gear 15. The forward gear 16 and the reverse gear 17 are each meshed with the transmission gear 15, and the forward gear 16 and the reverse gear 17 rotate in opposite directions in response to the rotation of the transmission gear 15. Furthermore, a through hole is formed in the center of the forward gear 16 and the center of the reverse gear 17, and the front portion of the propeller shaft 13 is inserted into these through holes. The forward gear 16 and the reverse gear 17 are not fixed to the propeller shaft 13 but are rotatable relative to the propeller shaft 13. A dog clutch 18 is disposed between the forward gear 16 and the reverse gear 17. The dog clutch 18 is attached to the front portion of the propeller shaft 13 so as to be unable to rotate relative to the propeller shaft 13 and to be movable in the front-rear direction relative to the propeller shaft 13. A shift plunger 19 is attached inside the front end of the propeller shaft 13 so as to be movable in the front-rear direction relative to the propeller shaft 13. The rear end of the shift plunger 19 is connected to the dog clutch 18, and the front end of the shift plunger 19 is located near the lower end of the shift rod 33 so that the rotation of the shift rod 33 is transmitted to the shift plunger 19 via a cam mechanism. When the shift rod 33 rotates due to the driving of the shift actuator 32, the rotation of the shift rod 33 is transmitted to the shift plunger 19 via the cam mechanism, causing the shift plunger 19 to move forward or backward, and in response, the dog clutch 18 moves forward or backward. When the dog clutch 18 moves forward, the dog clutch 18 and the forward gear 16 engage with each other, thereby transmitting the rotation of the forward gear 16 to the propeller shaft 13.On the other hand, when the dog clutch 18 moves rearward, the dog clutch 18 and the reverse gear 17 engage with each other, thereby transmitting the rotation of the reverse gear 17 to the propeller shaft 13 .

[0032] The propeller shaft 13 extends in the front-to-rear direction. The front portion of the propeller shaft 13 is located inside the lower case 27 and extends into the rotation transmission mechanism 14. The rear portion of the propeller shaft 13 is located outside the lower case 27. The propeller 20 is fixed to the rear portion of the propeller shaft 13 and rotates integrally with the propeller shaft 13.

[0033] The shift device 31 includes a shift actuator 32 and a shift rod 33. The shift actuator 32 is an actuator, such as a small motor, that controls movement of the dog clutch 18. The shift actuator 32 is provided in the front right portion of the upper part of the upper case 25. The shift rod 33 is a rod that transmits power from the shift actuator 32 to the shift plunger 19. The shift rod 33 extends vertically from the shift actuator 32 toward the front end of the shift plunger 19. The upper part of the shift rod 33 passes through the inside of a cylindrical pilot shaft 42, and the lower part of the shift rod 33 passes through the lower case 27. The upper end of the shift rod 33 is connected to the shift actuator 32, and the lower end of the shift rod 33 is located near the front end of the shift plunger 19. The shift rod 33 rotates when driven by the shift actuator 32. The rotational movement of the shift rod 33 is converted into linear movement in the front-to-rear direction of the shift plunger 19 by a cam mechanism provided between the lower end of the shift rod 33 and the front end of the shift plunger 19. As described above, the movement of the shift plunger 19 causes the dog clutch 18 to move.

[0034] The inverter 35 includes an inverter main body 36 including electric and electronic circuits that control the driving of the motor 3, and an inverter case 37 that houses the inverter main body 36. The inverter 35 is disposed above the reduction gear 9, and is attached to the upper case 25 using connecting members such as bolts.

[0035] The motor 3 is driven under the control of the inverter 35, causing the output shaft 4 of the motor 3 to rotate. As the output shaft 4 of the motor 3 rotates, the drive sprocket 10 of the reduction gear 9 rotates, and the rotation of the drive sprocket 10 is transmitted to the driven sprocket 11 via the silent chain 12, causing the driven sprocket 11 to rotate. During this time, the rotation of the output shaft 4 of the motor 3 is decelerated. The rotation of the driven sprocket 11 is transmitted to the forward gear 16 and reverse gear 17 via the drive shaft 8 and transmission gear 15 in this order. When the dog clutch 18 is moved forward under the control of the shift actuator 32, the rotation of the forward gear 16 is transmitted to the propeller shaft 13, causing the propeller shaft 13 and the propeller 20 to rotate in the forward direction. The forward rotation of the propeller 20 generates a thrust force that moves the vessel forward. On the other hand, when the dog clutch 18 is moved rearward under the control of the shift actuator 32, the rotation of the reverse gear 17 is transmitted to the propeller shaft 13, causing the propeller shaft 13 and the propeller 20 to rotate in the reverse direction. The reverse rotation of the propeller 20 generates a propulsive force that moves the boat backward.

[0036] (Details of each part of the mounting mechanism) In the mounting mechanism 40, the pair of left and right clamp brackets 41 and the swivel bracket 43 are disposed at the front of the upper part of the outboard motor body 2. Although not shown in detail, the swivel bracket 43 is disposed between the pair of clamp brackets 41. The swivel bracket 43 is connected to each clamp bracket 41 via a tilt shaft 44.

[0037] The pilot shaft 42 extends in the vertical direction and is rotatably supported by a swivel bracket 43. An upper mount fixing member 46 is coupled to the upper end of the pilot shaft 42, and front portions of a pair of left and right upper mounts 47 are fixed to the upper mount fixing member 46. The rear portions of the pair of upper mounts 47 each fit within the upper case 25 and are attached to the upper case 25 within the upper case 25. A lower mount fixing member 48 is coupled to the lower end of the pilot shaft 42, and front portions of a pair of left and right lower mounts 49 are fixed to the lower mount fixing member 48. The rear portions of the pair of lower mounts 49 are attached to the middle case 26.

[0038] 3 and 6, the upper end portion of the drive shaft 8 passes between a pair of upper mounts 47. The vertically intermediate portion of the drive shaft 8 passes between a pair of lower mounts 49.

[0039] The outboard motor body 2 is fixed to the boat by fixing each clamp bracket 41 to the transom 101 of the boat. However, the outboard motor body 2 can rotate laterally relative to the boat about the pilot shaft 42 as a rotation axis, thereby changing the direction of the propeller 20 in the lateral direction.

[0040] The swivel bracket 43 can rotate up and down relative to each clamp bracket 41, with the tilt shaft 44 serving as the rotation axis. This allows the outboard motor body 2 to rotate (tilt up and tilt down) up and down relative to the boat. A tilt actuator 45 is provided between the pair of clamp brackets 41. The tilt actuator 45 is, for example, a hydraulic cylinder or an electric cylinder. The outboard motor body 2 can tilt up and down by the power of the tilt actuator 45.

[0041] As described above, in the outboard motor 1 according to an embodiment of the present invention, the reduction gear 9 is disposed so that the front portion of the reduction gear 9 is located above the swivel bracket 43 and the rear portion of the reduction gear 9 is located above the motor 3, and when the outboard motor 1 is viewed from above, the reduction gear 9 is disposed so that its front portion overlaps the swivel bracket 43. By disposing the reduction gear 9 so that its front portion overlaps the swivel bracket 43 in this manner, the reduction gear 9 can be shifted forward so as to be closer to the boat to which the outboard motor 1 is attached, compared to when the entire reduction gear 9 is disposed behind the swivel bracket 43, and therefore the distance in the fore-and-aft direction between the reduction gear 9 and the transom 101 of the boat can be shortened.

[0042] Furthermore, the drive sprocket 10 of the reduction gear 9 is connected to the output shaft 4 of the motor 3. Therefore, the location of the motor 3 must be determined taking into consideration the location of the reduction gear 9, but in the outboard motor 1 of this embodiment, the location of the reduction gear 9 can be shifted forward so as to bring it closer to the boat, and therefore the location of the motor 3 can also be shifted forward so as to bring it closer to the boat. Therefore, the distance in the fore-and-aft direction between the motor 3 and the transom 101 of the boat can be shortened.

[0043] As described above, with the outboard motor 1 of this embodiment, the motor 3 and reduction gear 9, which are heavy objects, can be located closer to the boat, and therefore the center of gravity of the outboard motor 1 can be located closer to the boat. By locating the center of gravity of the outboard motor 1 closer to the boat, the force required to tilt up the outboard motor main body 2 can be reduced. This makes it possible to use a low-output actuator as the tilt actuator 45 that tilts up and down the outboard motor main body 2, thereby reducing the manufacturing cost of the outboard motor 1.

[0044] Furthermore, in the outboard motor 1 of this embodiment, the reduction gear 9 is positioned so that the front of the reduction gear 9 overlaps with the swivel bracket 43 when the outboard motor 1 is viewed from above, and by positioning the reduction gear 9 so that its front overlaps with the swivel bracket 43 in this manner, the motor 3 can be shifted forward so as to be closer to the swivel bracket 43. Therefore, with the outboard motor 1 of this embodiment, the dimension of the outboard motor 1 in the fore-and-aft direction can be reduced.

[0045] In addition, in the reduction gear 9 of the outboard motor 1 of this embodiment, the drive sprocket 10 is disposed above the motor 3 and coaxially with the output shaft 4 of the motor 3, and the driven sprocket 11 is disposed above the drive shaft 8 and coaxially with the drive shaft 8, with a portion of the driven sprocket 11 located above the swivel bracket 43. With this configuration, the motor 3, drive shaft 8, and reduction gear 9 can be located closer to the boat, and therefore the center of gravity of the outboard motor 1 can be located closer to the boat.

[0046] Furthermore, in the outboard motor 1 of this embodiment, the reduction gear 9 includes a drive sprocket 10, a driven sprocket 11, and a silent chain 12 stretched between the drive sprocket 10 and the driven sprocket 11. If the reduction gear were constructed with multiple gears meshing with each other, the noise emitted from the reduction gear would be large and difficult to reduce unless the shape, precision, surface texture, etc. of each gear were properly managed. In contrast, if the reduction gear were constructed with a silent chain stretched between multiple sprockets, the noise emitted from the reduction gear can be easily reduced. Therefore, the reduction gear 9 of the outboard motor 1 of this embodiment makes it easy to reduce the noise emitted from the reduction gear 9.

[0047] Furthermore, in this embodiment, the reduction gear 9 has a silent chain 12 wound around the drive sprocket 10 and the driven sprocket 11. Therefore, by changing the length of the silent chain 12, the distance between the drive sprocket 10 and the driven sprocket 11 can be easily adjusted without changing the gear ratio. This facilitates the design and manufacture of the outboard motor 1. To explain this further using an example, in the outboard motor 1, as shown in FIG. 3, the output shaft 4 of the motor 3 and the drive sprocket 10 of the reduction gear 9 are arranged coaxially. The drive shaft 8, the driven sprocket 11 of the reduction gear 9, and the transmission gear 15 of the rotation transmission mechanism 14 are also arranged coaxially. Therefore, when designing the outboard motor 1, the distance between the axis of the drive sprocket 10 and the axis of the driven sprocket 11 in the reduction gear 9 needs to match the distance between the axis of the output shaft 4 of the motor 3 and the axis of the transmission gear 15 of the rotation transmission mechanism 14. With the reduction gear 9, the distance between the axis of the drive sprocket 10 and the axis of the driven sprocket 11 can be easily changed by changing the length of the silent chain 12 without changing the gear ratio. Therefore, the distance between the axis of the drive sprocket 10 and the axis of the driven sprocket 11 can be easily matched with the distance between the axis of the output shaft 4 of the motor 3 and the axis of the transmission gear 15 of the rotation transmission mechanism 14. In contrast, if the reduction gear 9 were configured to mesh two gears, it would be difficult to change the distance between the axis of one gear and the axis of the other gear without changing the gear ratio, which could make it difficult to match the distance between the axes of the two gears in the reduction gear 9 with the distance between the axis of the output shaft 4 of the motor 3 and the axis of the transmission gear 15 of the rotation transmission mechanism 14. In this way, the outboard motor 1 of this embodiment, which is equipped with a reduction gear device 9 having a drive sprocket 10, a driven sprocket 11, and a silent chain 12, can simplify the design and manufacture of the outboard motor compared to other outboard motors equipped with a reduction gear device that has a configuration in which two gears mesh together.

[0048] Furthermore, in the outboard motor 1 of this embodiment, the inverter 35 is disposed above the reduction gear 9. As described above, in the outboard motor 1 of this embodiment, the reduction gear 9 can be shifted forward so as to be closer to the boat. Therefore, by disposing the inverter 35 above the reduction gear 9, the inverter 35 can be shifted forward together with the reduction gear 9 so as to be closer to the boat. Therefore, even when the inverter 35 is provided in the outboard motor 1, the center of gravity of the outboard motor 1 can be brought closer to the boat.

[0049] Furthermore, in the outboard motor 1 of this embodiment, the reduction gear 9 is located above the upper mount 47. By positioning the reduction gear 9 above the upper mount 47, which is positioned close to the boat, the reduction gear 9 and the motor 3 can be brought closer to the boat, and therefore the center of gravity of the outboard motor 1 can be brought closer to the boat.

[0050] Furthermore, in the outboard motor 1 of this embodiment, the motor 3 is disposed below the upper mount 47, and the reduction gear 9 is disposed above the upper mount 47. With this configuration, the motor 3 and reduction gear 9, which are vibration sources, can be placed closer to the upper mount 47, effectively suppressing vibration of the outboard motor 1 caused by vibrations generated by them. In other words, when the motor 3 and reduction gear 9 are operating, the vibrations generated by the motor 3 and reduction gear 9 cause the outboard motor 1 to vibrate in a swinging manner around the upper mount 47. Therefore, by placing the motor 3 and reduction gear 9 closer to the upper mount 47, the amplitude of vibration of the outboard motor 1 caused by vibrations generated by the motor 3 and reduction gear 9 can be reduced.

[0051] In the outboard motor 1 of this embodiment, the drive shaft 8 passes between a pair of left and right upper mounts 47. This allows each upper mount 47 to function as a bulkhead that prevents external objects from colliding with the drive shaft 8, and the drive shaft 8 can be protected by each upper mount 47.

[0052] In the outboard motor 1 of this embodiment, the shift actuator 32 is attached to the upper case 25 that houses the reduction gear 9. This allows the shift actuator 32 to be attached to the outboard motor 1 without providing a separate bracket.

[0053] In the above embodiment, the silent chain 12 is used as the chain of the reduction gear 9, but other types of chains such as a roller chain may also be used as the chain of the reduction gear 9. The reduction gear 9 may also be configured to include multiple pulleys and a belt stretched between the pulleys. The reduction gear 9 may also be configured to mesh with multiple gears.

[0054] 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]

[0055] 1 outboard motor 2 Outboard motor body 3 motors 8 Drive shaft 9. Reduction gear (first transmission mechanism) 10 Drive sprocket (first rotation transmission element) 11 Driven sprocket (second rotation transmission element) 12 Silent Chain 13 Propeller shaft 14 Rotation transmission mechanism (second transmission mechanism) 20 propellers 25 Upper case (case) 32 Shift actuator 35 inverter 40 Mounting mechanism 41 Clamp bracket 42 Pilot shaft 43 Swivel bracket 47 Upper Mount 49 Lower Mount

Claims

1. 1. An outboard motor comprising: an outboard motor body; and a mounting mechanism provided in front of the outboard motor body for mounting the outboard motor body to a boat, the outboard motor body includes a motor, a drive shaft, a first transmission mechanism that transmits rotation of the motor to the drive shaft, a propeller shaft provided with a propeller, and a second transmission mechanism that transmits rotation of the drive shaft to the propeller shaft; the first transmission mechanism is disposed so that a front portion of the first transmission mechanism is located above the mounting mechanism and a rear portion of the first transmission mechanism is located above the motor.

2. The attachment mechanism includes: a clamp bracket for fixing the outboard motor body to the boat; a swivel bracket connected to the clamp bracket and supporting the outboard motor body so that the outboard motor body can rotate laterally relative to the boat, 2. An outboard motor according to claim 1, wherein a front portion of said first transmission mechanism is located above said swivel bracket.

3. the drive shaft extends in a vertical direction and is disposed in front of the motor; The first transmission mechanism includes: a first rotation transmission element, which is a gear, a sprocket, or a pulley, that inputs rotation of the motor to the first transmission mechanism; a second rotation transmitter, which is a gear, a sprocket, or a pulley, that outputs the rotation of the motor input to the first transmission mechanism from the first transmission mechanism to the drive shaft; 3. The outboard motor according to claim 2, wherein the first rotational transmission member is disposed above the motor and coaxially with an output shaft of the motor, the second rotational transmission member is disposed above the drive shaft and coaxially with the drive shaft, and a portion of the second rotational transmission member is located above the swivel bracket.

4. The first transmission mechanism includes: a drive sprocket that inputs rotation of the motor to the first transmission mechanism; a driven sprocket that outputs the rotation of the motor input to the first transmission mechanism from the first transmission mechanism to the drive shaft; 2. The outboard motor according to claim 1, further comprising a silent chain wound around the drive sprocket and the driven sprocket.

5. an inverter for controlling the driving of the motor; 2. The outboard motor according to claim 1, wherein the inverter is disposed above the first transmission mechanism.

6. the mounting mechanism comprises a clamp bracket that fixes the outboard motor body to the boat, a pilot shaft that serves as an axis for rotation of the outboard motor body in the left-right direction, a swivel bracket that is connected to the clamp bracket and rotatably supports the pilot shaft, an upper mount that connects an upper end of the pilot shaft to the outboard motor body, and a lower mount that connects a lower end of the pilot shaft to the outboard motor body, 2. An outboard motor in accordance with claim 1, wherein said first transmission mechanism is located above said upper mount.

7. 7. The outboard motor according to claim 6, wherein the motor is disposed below the upper mount, and the first transmission mechanism is disposed above the upper mount.

8. a pair of left and right upper mounts; 7. An outboard motor in accordance with claim 6, wherein said drive shaft passes between said pair of upper mounts.

9. 2. The outboard motor according to claim 1, further comprising a case that houses the first transmission mechanism, the case being disposed above the motor, and a shift actuator that controls switching of the rotation direction of the propeller being attached to the case.

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