Ship propulsion machine

Abstract

To prevent significant increase of the size of a ship propulsion machine even when the ship propulsion machine is provided with two motors and a mechanism that switches a propeller rotation mode.SOLUTION: A power unit 2 of an outboard engine includes: a lower motor 21; an upper motor 41; a dog clutch 62 which connects both or one of an upper end part of a motor shaft 22 of the lower motor 21 and a lower end part of a motor shaft 42 of the upper motor 41 to a drive shaft 4; and a switching mechanism 71 which moves the dog clutch 62 to switch a connecting mode between the motor shaft 22 / the motor shaft 42 and the drive shaft 4. The dog clutch 62 and the switching mechanism 71 are disposed between the lower motor 21 and the upper motor 41.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a marine propulsion device that uses a motor (electric motor) as a power source for generating the propulsion force of a ship.

Background Art

[0002] Japanese Patent Application Laid-Open No. 2005-153727 (Patent Document 1) describes an outboard motor that uses a motor as a power source for generating the propulsion force of a ship. In this outboard motor, the motor is provided at the upper part of the outboard motor, and a propeller shaft to which a propeller is fixed is provided at the lower part of the outboard motor. Further, a drive shaft extending in the vertical direction is provided between the motor and the propeller shaft, and the power of the motor is transmitted to the propeller shaft via the drive shaft.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, as a power source for generating the propulsion force of a ship, a method of using two motors to rotate a propeller, a method of rotating the propeller by the combined force of the two motors, a method of rotating the propeller by the power of only one of the two motors, and a method of rotating the propeller by the power of only the other of the two motors. By switching between at least any two of these methods, the performance of the marine propulsion device can be improved.

[0005] However, when a mechanism for switching the method of rotating two motors and a propeller is provided in a marine propulsion device, the marine propulsion device may be significantly enlarged as compared with a marine propulsion device provided with only one motor as a power source for generating the propulsion force of a ship.

[0006] The present invention has been made in view of the problems as described above, and an object of the present invention is to prevent a significant increase in the size of a marine propulsion unit even when the marine propulsion unit is provided with two motors and a mechanism for switching the method of rotating a propeller.

Means for Solving the Problems

[0007] In order to solve the above problems, the present invention provides a marine propulsion unit including a power unit that generates power, a propeller shaft to which a propeller is fixed, and a drive shaft provided between the power unit and the propeller shaft for transmitting the power generated by the power unit to the propeller shaft. The power unit includes a first motor having a first motor shaft extending in the vertical direction, a second motor disposed above the first motor and having a second motor shaft extending in the vertical direction, a connecting member movably disposed in the vertical direction between the first motor and the second motor, the lower end of which is provided with a first connecting portion for connecting itself to the upper end of the first motor shaft, and the upper end of which is provided with a second connecting portion for connecting itself to the lower end of the second motor shaft, and a switching mechanism disposed between the first motor and the second motor for switching the connection mode of the first motor shaft, the second motor shaft, and the drive shaft among at least any two of the following modes: (a) a mode in which both the first motor shaft and the second motor shaft are connected to the drive shaft; (b) a mode in which the first motor shaft is connected to the drive shaft and the second motor shaft is not connected to the drive shaft; and (c) a mode in which the second motor shaft is connected to the drive shaft and the first motor shaft is not connected to the drive shaft.

Advantages of the Invention

[0008] According to the present invention, even when two motors and a mechanism for switching the method of rotating the propeller are provided in a marine propulsion unit, it is possible to prevent the significant enlargement of the marine propulsion unit.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Embodiments for Carrying Out the Invention

[0010] The ship propulsion machine according to an embodiment of the present invention includes a power unit that generates power, a propeller shaft to which a propeller is fixed, and a drive shaft that is provided between the power unit and the propeller shaft and transmits the power generated by the power unit to the propeller shaft. Further, the power unit includes a first motor, a second motor, a connection member, and a switching mechanism.

[0011] The first motor has a first motor shaft extending in the vertical direction.

[0012] The second motor is disposed above the first motor. Further, the second motor has a second motor shaft extending in the vertical direction.

[0013] The connection member is disposed between the first motor and the second motor so as to be movable in the vertical direction. Further, a first connection portion for connecting the connection member to the upper end portion of the first motor shaft is provided at the lower end portion of the connection member. Further, a second connection portion for connecting the connection member to the lower end portion of the second motor shaft is provided at the upper end portion of the connection member.

[0014] The switching mechanism is disposed between the first motor and the second motor. Further, the switching mechanism switches the connection mode of the first motor shaft, the second motor shaft, and the drive shaft between at least any two of the following three modes by moving the connection member upward or downward. (a) A mode in which both the first motor shaft and the second motor shaft are connected to the drive shaft (b) A mode in which the first motor shaft is connected to the drive shaft and the second motor shaft is not connected to the drive shaft (c) A mode in which the second motor shaft is connected to the drive shaft and the first motor shaft is not connected to the drive shaft In the aspect of (a) above, the power of both the first motor and the second motor is transmitted to the drive shaft. Thereby, the propeller rotates by the combined power of the power of the first motor and the power of the second motor. In the aspect of (b) above, the power of the first motor is transmitted to the drive shaft, but the power of the second motor is not transmitted to the drive shaft. Thereby, among the two motors of the power unit, the propeller rotates only by the power of the first motor. In the aspect of (c) above, the power of the second motor is transmitted to the drive shaft, but the power of the first motor is not transmitted to the drive shaft. Thereby, among the two motors of the power unit, the propeller rotates only by the power of the second motor. According to the switching mechanism, the method of rotating the propeller can be switched between at least any two of the method of rotating the propeller by the combined force of the power of the two motors, the method of rotating the propeller only by the power of one of the two motors, and the method of rotating the propeller only by the power of the other of the two motors.

[0015] Here, some specific examples of the structure in which the connection mode of the first motor shaft, the second motor shaft, and the drive shaft is switched by the movement of the connection member will be described.

[0016] (The first example) FIG. 10(A) shows a first example of the structure in which the connection mode of the first motor shaft, the second motor shaft, and the drive shaft is switched by the movement of the connection member. FIG. 10(B) shows a state in which the connection member has moved downward in the first example, and FIG. 10(C) shows a state in which the connection member has moved upward in the first example.

[0017] In the first example, the connection mode of the first motor shaft, the second motor shaft, and the drive shaft is switched among (a), (b), and (c) above by the movement of the connection member.

[0018] In FIG. 10(A), the first motor 111 has a motor shaft 112 (first motor shaft) extending in the vertical direction. The second motor 121 is disposed above the first motor 111. The second motor 121 also has a motor shaft 122 (second motor shaft) extending in the vertical direction. The motor shaft 112 of the first motor 111 is formed in a cylindrical shape, and the upper portion of the drive shaft 131 passes through the inner peripheral side of the motor shaft 112 and reaches between the first motor 111 and the second motor 121. The outer peripheral surface of the drive shaft 131 is separated from the inner peripheral surface of the motor shaft 112 of the first motor 111, and the drive shaft 131 can rotate independently of the motor shaft 112. The connecting member 141 is disposed between the first motor 111 and the second motor 121. The connecting member 141 is attached to the outer peripheral side of the upper portion of the drive shaft 131 in a non-rotatable manner with respect to the drive shaft 131 and is movable in the vertical direction with respect to the drive shaft 131. A first connecting portion 145 is provided at the lower end portion of the connecting member 141, and a connected portion 113 is provided at the upper end portion of the motor shaft 112 of the first motor 111. The first connecting portion 145 and the connected portion 113 each have a shape that can be fitted to each other, for example. A second connecting portion 146 is provided at the upper end portion of the connecting member 141, and a connected portion 123 is provided at the lower end portion of the motor shaft 122 of the second motor 121. The second connecting portion 146 and the connected portion 123 each have a shape that can be fitted to each other, for example.

[0019] In FIG. 10(A), the connecting member 141 is located at the vertical intermediate portion between the upper end portion of the motor shaft 112 of the first motor 111 and the lower end portion of the motor shaft 122 of the second motor 121. In this state, the first connecting portion 145 of the connecting member 141 is connected to the connected portion 113 of the motor shaft 112 of the first motor 111, and at the same time, the second connecting portion 146 of the connecting member 141 is connected to the connected portion 123 of the motor shaft 122 of the second motor 121. As a result, both the motor shaft 112 of the first motor 111 and the motor shaft 122 of the second motor 121 are connected to the drive shaft 131 via the connecting member 141.

[0020] As can be seen by comparing FIG. 10(B) with FIG. 10(A), in FIG. 10(B), the connecting member 141 has moved downward. As a result, the first connecting portion 145 of the connecting member 141 is connected to the connected portion 113 of the motor shaft 112 of the first motor 111, but the connection between the second connecting portion 146 of the connecting member 141 and the connected portion 123 of the motor shaft 122 of the second motor 121 has been released. As a result, the motor shaft 112 of the first motor 111 is connected to the drive shaft 131 via the connecting member 141, but the motor shaft 122 of the second motor 121 is not connected to the drive shaft 131.

[0021] As can be seen by comparing FIG. 10(C) with FIG. 10(A), in FIG. 10(C), the connecting member 141 has moved upward. As a result, the second connecting portion 146 of the connecting member 141 is connected to the connected portion 123 of the motor shaft 122 of the second motor 121, but the connection between the first connecting portion 145 of the connecting member 141 and the connected portion 113 of the motor shaft 112 of the first motor 111 has been released. As a result, the motor shaft 122 of the second motor 121 is connected to the drive shaft 131 via the connecting member 141, but the motor shaft 112 of the first motor 111 is not connected to the drive shaft 131.

[0022] (Second example) FIG. 10(D) shows a second example of a structure in which the connection mode of the first motor shaft, the second motor shaft, and the drive shaft is switched by the movement of the connection member. FIG. 10(E) shows a state in which the connection member has moved upward in the second example.

[0023] In the second example, the connection mode of the first motor shaft, the second motor shaft, and the drive shaft is switched between the above (a) and (b) by the movement of the connection member.

[0024] In FIG. 10(D), the first motor 211 has a motor shaft 212 (first motor shaft) extending in the vertical direction. A drive shaft 231 is connected to the lower end of the motor shaft 212 of the first motor 211, and the motor shaft 212 of the first motor 211 rotates together with the drive shaft 231. The second motor 221 is disposed above the first motor 211. The second motor 221 also has a motor shaft 222 (second motor shaft) extending in the vertical direction. The connection member 241 is disposed between the first motor 211 and the second motor 221. A first connection portion 245 is provided at the lower end of the connection member 241, and a connected portion 213 is provided at the upper end of the motor shaft 212 of the first motor 211. The first connection portion 245 and the connected portion 213 each have, for example, a shape that can be fitted to each other. A second connection portion 246 is provided at the upper end of the connection member 241, and a connected portion 223 is provided at the lower end of the motor shaft 222 of the second motor 221. The second connection portion 246 and the connected portion 223 each have, for example, a shape that can be fitted to each other.

[0025] In FIG. 10(D), the connecting member 241 is located at the vertical intermediate portion between the upper end of the motor shaft 212 of the first motor 211 and the lower end of the motor shaft 222 of the second motor 221. In this state, the first connecting portion 245 of the connecting member 241 is connected to the connected portion 213 of the motor shaft 212 of the first motor 211, and at the same time, the second connecting portion 246 of the connecting member 241 is connected to the connected portion 223 of the motor shaft 222 of the second motor 221. Thereby, the motor shaft 212 of the first motor 211 and the motor shaft 222 of the second motor 221 are connected to each other via the connecting member 241. As a result, the motor shaft 212 of the first motor 211 is directly connected to the drive shaft 231, and at the same time, the motor shaft 222 of the second motor 221 is connected to the drive shaft 231 via the connecting member 241 and the motor shaft 212 of the first motor 211. That is, both the motor shaft 212 of the first motor 211 and the motor shaft 222 of the second motor 221 are connected to the drive shaft 231.

[0026] As can be seen by comparing FIG. 10(D) with FIG. 10(E), in FIG. 10(E), the connecting member 241 has moved upward. As a result, the second connecting portion 246 of the connecting member 241 is connected to the connected portion 223 of the motor shaft 222 of the second motor 221, but the connection between the first connecting portion 245 of the connecting member 241 and the connected portion 213 of the motor shaft 212 of the first motor 211 has been released. Thereby, the motor shaft 212 of the first motor 211 and the motor shaft 222 of the second motor 221 are separated from each other. As a result, the motor shaft 212 of the first motor 211 is connected to the drive shaft 231, but the motor shaft 222 of the second motor 221 is not connected to the drive shaft 231.

[0027] In addition, in FIG. 10(D), by moving the connecting member 241 downward, the first connecting portion 245 of the connecting member 241 is connected to the connected portion 213 of the motor shaft 212 of the first motor 211, and the connection between the second connecting portion 246 of the connecting member 241 and the connected portion 223 of the motor shaft 222 of the second motor 221 can be released. Thereby, although the motor shaft 212 of the first motor 211 is connected to the drive shaft 231, a state can be created in which the motor shaft 222 of the second motor 221 is not connected to the drive shaft 231.

[0028] (Third example) FIG. 10(F) shows a third example of a structure in which the connection modes of the first motor shaft, the second motor shaft, and the drive shaft are switched by the movement of the connecting member.

[0029] In the third example, similar to the second example, the connection modes of the first motor shaft, the second motor shaft, and the drive shaft are switched between the above (a) and (b) by the movement of the connecting member. However, the third example is different from the second example in that the connecting member is arranged non-coaxially with each motor shaft.

[0030] In FIG. 10(F), the first motor 311 has a motor shaft 312 (first motor shaft) extending in the vertical direction. A drive shaft 331 is connected to the lower end of the motor shaft 312 of the first motor 311, and the motor shaft 312 of the first motor 311 rotates together with the drive shaft 331. The second motor 321 is disposed above the first motor 311. Further, the second motor 321 has a motor shaft 322 (second motor shaft) extending in the vertical direction. The connecting member 341 is disposed between the first motor 311 and the second motor 321. Also, in the above second example, the motor shaft 212 of the first motor 211, the motor shaft 222 of the second motor 221, and the connecting member 241 are respectively arranged coaxially with each other. However, in the third example, although the motor shaft 312 of the first motor 311 and the motor shaft 322 of the second motor 321 are arranged coaxially with each other, the connecting member 341 is arranged non-coaxially with these motor shafts 312, 322. A shaft 347 that is non-coaxial with the motor shafts 312, 322 and extends in the vertical direction parallel to the motor shafts 312, 322 is provided between the first motor 311 and the second motor 321, and the connecting member 341 is rotatably and vertically movably attached to the shaft 347. Further, a first connecting portion 345 is provided at the lower end of the connecting member 341, and a connected portion 313 is provided at the upper end of the motor shaft 312 of the first motor 311. A plurality of teeth that can mesh with each other, for example, are provided on the outer peripheral surfaces of the first connecting portion 345 and the connected portion 313. Also, a second connecting portion 346 is provided at the upper end of the connecting member 341, and a connected portion 323 is provided at the lower end of the motor shaft 322 of the second motor 321. A plurality of teeth that can mesh with each other, for example, are provided on the outer peripheral surfaces of the second connecting portion 346 and the connected portion 323.

[0031] In Fig. 10(F), the first connecting portion 345 of the connecting member 341 is connected to the connected portion 313 of the motor shaft 312. At the same time, the second connecting portion 346 of the connecting member 341 is connected to the connected portion 323 of the motor shaft 322. As a result, the motor shaft 312 and the motor shaft 322 are connected to each other via the connecting member 341. Consequently, both the motor shaft 312 of the first motor 311 and the motor shaft 322 of the second motor 321 are connected to the drive shaft 331.

[0032] From the state shown in Fig. 10(F), by moving the connecting member 341 upward or downward, the connection between the first connecting portion 345 of the connecting member 341 and the connected portion 313 of the motor shaft 312, and the connection between the second connecting portion 346 of the connecting member 341 and the connected portion 323 of the motor shaft 322 can be released respectively, and the motor shaft 312 and the motor shaft 322 can be separated from each other. When the motor shaft 312 and the motor shaft 322 are separated from each other, the connection between the motor shaft 322 and the drive shaft 331 is broken.

[0033] The ship propulsion device of the present embodiment can adopt any of the three above-described examples as a structure in which the connection mode of the first motor shaft, the second motor shaft, and the drive shaft is switched by the movement of the connecting member. Note that, in the ship propulsion device of the present embodiment, the structure in which the connection mode of the first motor shaft, the second motor shaft, and the drive shaft is switched by the movement of the connecting member is not limited to the three above-described examples.

[0034] According to the ship propulsion machine of the present embodiment, even when two motors and a mechanism for switching the method of rotating the propeller are provided, it is possible to prevent the ship propulsion machine from becoming significantly larger. Specifically, by arranging the first motor and the second motor vertically so that their respective motor shafts extend in the vertical direction, the upper end of the first motor shaft and the lower end of the second motor shaft can be brought closer to each other within the space between the first motor and the second motor. Then, by arranging the connecting member and the switching mechanism between the first motor and the second motor, the upper end of the first motor shaft, the lower end of the second motor shaft, the connecting member, and the switching mechanism can be concentrated between the first motor and the second motor. Furthermore, by concentrating the upper end of the first motor shaft, the lower end of the second motor shaft, the connecting member, and the switching mechanism, the connecting member and the switching mechanism can be formed compactly. As a result, it is possible to prevent the ship propulsion machine from becoming significantly larger compared to a ship propulsion machine with only one motor.

Example

[0035] Hereinafter, as an example of the present invention, a case where the present invention is applied to an outboard motor which is a form of a ship propulsion machine will be described. In the description of this embodiment, when describing the directions of up (Ud), down (Dd), front (Fd), rear (Bd), left (Ld), and right (Rd), follow the arrows drawn in the lower right of each figure.

[0036] (Outboard motor) FIG. 1 shows an outboard motor 1 according to an embodiment of the present invention. In FIG. 1, the outboard motor 1 includes a power unit 2, a propeller 3, a drive shaft 4, a propeller shaft 5, and a gear mechanism 6.

[0037] The power unit 2 generates power for propelling the ship. The power unit 2 is arranged at the upper part of the outboard motor 1 so as to be located above the water surface when the outboard motor 1 is attached to the ship. Further, the power unit 2 is fixed to a motor holder 9 provided at the upper part of the outboard motor 1.

[0038] The propeller 3 converts the power generated by the power unit 2 into propulsive force. The propeller 3 is disposed at the lower part of the outboard motor 1 so as to be located underwater when the outboard motor 1 is attached to a ship.

[0039] The drive shaft 4, the propeller shaft 5, and the gear mechanism 6 transmit the power generated by the power unit 2 to the propeller 3. The drive shaft 4 extends vertically from the upper part to the lower part of the outboard motor 1. The upper part of the drive shaft 4 enters the interior of the power unit 2. The propeller shaft 5 is disposed at the lower part of the outboard motor 1 and extends in the front-rear direction. The propeller 3 is fixed to the rear part of the propeller shaft 5. The gear mechanism 6 is disposed at the front part of the lower part of the outboard motor 1. The gear mechanism 6 includes a drive gear 7 and a driven gear 8. The drive gear 7 is fixed to the lower end of the drive shaft 4, and the driven gear 8 is fixed to the front end of the propeller shaft 5. Both the drive gear 7 and the driven gear 8 are bevel gears. By the meshing of these gears, the rotation of the drive shaft 4 around the vertical axis is converted into the rotation of the propeller shaft 5 around the horizontal axis. The drive shaft 4 receives the power of the power unit 2 and rotates, and the rotation of the drive shaft 4 is transmitted to the propeller shaft 5 via the gear mechanism 6, whereby the propeller 3 rotates together with the propeller shaft 5.

[0040] In addition, a motor cover 10 that covers the power unit 2 and the motor holder 9 is provided at the upper part of the outboard motor 1. The motor cover 10 is divided into a bottom cover 11 that covers the lower part of the power unit 2 and the motor holder 9, and a top cover 12 that covers the upper part of the power unit 2. Also, a drive shaft case 13 that covers the outer peripheral side of the drive shaft 4 is provided at the middle part in the vertical direction of the outboard motor 1. Further, a gear case 14 that covers the gear mechanism 6 and the front part of the propeller shaft 5 is provided at the lower part of the outboard motor 1. Moreover, a clamp mechanism 15 for detachably fixing the outboard motor 1 to the hull of a ship is provided on the outboard motor 1.

[0041] (Power Unit) Figure 2 shows the power unit 2 and the motor holder 9 as viewed from the upper left front. Figure 3 shows the power unit 2 as viewed from the left. Figure 4 shows the power unit 2 as viewed from the front. Figure 5 shows a cross-section of the power unit 2 cut along the cutting line V-V in Figure 4 as viewed from the left (right in Figure 4).

[0042] As shown in Figure 2, the power unit 2 includes a lower motor 21, a lower inverter 35, an upper motor 41, an upper inverter 55, and a power switching device 61.

[0043] The lower motor 21 is an alternating current motor, that is, an AC motor. As shown in Figure 5, the lower motor 21 includes a motor shaft 22, a rotor 23 provided on the outer peripheral side of the motor shaft 22, a stator 24 provided on the outer peripheral side of the rotor 23, and a cylindrical motor case 25 provided on the outer peripheral side of the stator 24. The rotor 23 rotates together with the motor shaft 22, and the stator 24 is fixed to the motor case 25. Further, the motor shaft 22 is formed in a cylindrical shape. In other words, a through hole penetrating in the axial direction is formed in the central portion of the motor shaft 22.

[0044] Furthermore, as shown in FIG. 2, the lower motor 21 includes a bottom motor bracket 26 and a top motor bracket 27. The bottom motor bracket 26 is formed in a polygonal or circular plate shape and is disposed below the motor case 25 so as to generally close the lower part of the motor case 25. The lower part of the motor case 25 is fixed to the bottom motor bracket 26. For example, a plurality of motor fixing portions 25A protruding outward are provided at the lower part of the motor case 25, and these motor fixing portions 25A are fixed to the bottom motor bracket 26. Also, as shown in FIG. 5, a motor shaft insertion hole 26A is formed at the center of the bottom motor bracket 26. The lower end portion of the motor shaft 22 is rotatably supported via a bearing 31 within the motor shaft insertion hole 26A. Also, as shown in FIG. 2, the bottom motor bracket 26 is provided on the upper surface of the front portion of the motor holder 9 and is fixed to the motor holder 9.

[0045] The top motor bracket 27 is formed in a polygonal or circular plate shape and is disposed above the motor case 25 so as to generally close the upper part of the motor case 25, as shown in FIG. 2. The upper part of the motor case 25 is fixed to the top motor bracket 27. For example, a plurality of motor fixing portions 25B protruding outward are provided at the upper part of the motor case 25, and these motor fixing portions 25B are fixed to the top motor bracket 27. Also, a motor shaft insertion hole 27A is formed at the center of the top motor bracket 27, as shown in FIG. 5. The upper end portion of the motor shaft 22 is rotatably supported via a bearing 32 within the motor shaft insertion hole 27A.

[0046] The lower inverter 35 is a device that converts the current supplied from the battery to drive the lower motor 21 from direct current to alternating current. Inverter mounting portions 30 are provided at the left rear and right rear portions of the bottom motor bracket 26 and at the left rear and right rear portions of the top motor bracket 27. The lower inverter 35 is fixed to the rear portion of the lower motor 21 by being mounted on the inverter mounting portions 30.

[0047] The upper motor 41 is an AC motor. In this embodiment, the upper motor 41 is the same as the lower motor 21 in terms of the basic configuration as an AC motor and the performance related to power generation such as output and torque. The upper motor 41 includes a motor shaft 42, a rotor 43, a stator 44, and a cylindrical motor case 45, almost the same as the lower motor 21. However, the motor shaft 42 of the upper motor 41 is different from the motor shaft 22 of the lower motor 21 and is not cylindrical. That is, a through hole penetrating the central portion of the motor shaft 42 in the axial direction is not formed. Note that the motor shaft 42 may be formed in a cylindrical shape for the purpose of reducing the weight of the motor shaft 42 or the like.

[0048] In addition, the upper motor 41 includes a bottom motor bracket 46 and a top motor bracket 49. The bottom motor bracket 46 is formed in a polygonal or circular plate shape and is disposed below the motor case 45 so as to generally close the lower part of the motor case 45. The lower part of the motor case 45 is fixed to the bottom motor bracket 46 via a plurality of motor fixing portions 45A protruding outward from the lower part of the motor case 45, for example. A motor shaft insertion hole 46A is formed in the central portion of the bottom motor bracket 46. The lower end portion of the motor shaft 42 is rotatably supported in the motor shaft insertion hole 46A via a bearing 51.

[0049] The top motor bracket 49 is formed in a polygonal or circular plate shape and is disposed above the motor case 45 so as to generally close the upper part of the motor case 45. The upper part of the motor case 45 is fixed to the top motor bracket 49 via a plurality of motor fixing portions 45B protruding outward from the upper part of the motor case 45, for example. A motor shaft insertion hole 49A is formed in the central portion of the top motor bracket 49. The upper end portion of the motor shaft 42 is rotatably supported in the motor shaft insertion hole 49A via a bearing 52.

[0050] The upper inverter 55 is a device that converts the current supplied from the battery from direct current to alternating current in order to drive the upper motor 41. The upper inverter 55 is fixed to the rear part of the upper motor 41 by being attached to the inverter mounting portions 50 provided at the left rear and right rear portions of the bottom motor bracket 46 and the left rear and right rear portions of the top motor bracket 49.

[0051] The upper motor 41 is disposed above the lower motor 21. The lower motor 21 and the upper motor 41 are arranged such that the motor shafts 22 and 42 extend in the vertical direction respectively. The lower motor 21 and the upper motor 41 are arranged such that the motor shafts 22 and 42 are coaxial respectively.

[0052] As shown in FIGS. 2 to 5, the power unit 2 is provided with a plurality of support members 85 for fixing the upper motor 41 to the lower motor 21. The upper motor 41 is supported by these support members 85 at a position above the lower motor 21 and away from the lower motor 21. Each support member 85 is formed in a columnar shape extending in the vertical direction by, for example, a metal material or the like. Each support member 85 is disposed between the top motor bracket 27 of the lower motor 21 and the bottom motor bracket 46 of the upper motor 41. The lower part of each support member 85 is fixed to the top motor bracket 27 of the lower motor 21, and the upper part of each support member 85 is fixed to the bottom motor bracket 46 of the upper motor 41. In this embodiment, a through hole penetrating in the axial direction is formed in the central part of each support member 85. Further, through holes penetrating in the vertical direction are formed in the portions of the top motor bracket 27 of the lower motor 21 and the bottom motor bracket 46 of the upper motor 41 where each support member 85 is disposed. Each support member 85 is fixed between the top motor bracket 27 and the bottom motor bracket 46 by inserting a bolt 86 into the through holes of the support member 85, the top motor bracket 27 of the lower motor 21, and the bottom motor bracket 46 of the upper motor 41 respectively, and fastening a nut 87 to the end of the bolt 86. Thereby, the upper motor 41 is supported by the lower motor 21.

[0053] The plurality of support members 85 are arranged on the outer peripheral side portions of the top motor bracket 27 and the bottom motor bracket 46, respectively. FIG. 6 shows a state of a cross section of the power unit 2 cut along the cutting line VI-VI in FIG. 3 as viewed from above. As shown in FIG. 6, in this embodiment, two of the seven support members 85 are arranged on the left portions of the top motor bracket 27 and the bottom motor bracket 46, two other support members 85 are arranged on the right portions of the top motor bracket 27 and the bottom motor bracket 46, and the remaining three support members 85 are arranged on the rear portions of the top motor bracket 27 and the bottom motor bracket 46.

[0054] A space is formed between the lower motor 21 and the upper motor 41 by the plurality of support members 85. As shown in FIG. 5, in the space between the lower motor 21 and the upper motor 41, the upper end portion of the motor shaft 22 of the lower motor 21 and the lower end portion of the motor shaft 42 of the upper motor 41 are arranged to face each other and approach each other.

[0055] Also, the upper portion of the drive shaft 4 is inserted into the inner peripheral side of the motor shaft 22 of the lower motor 21. The upper portion of the drive shaft 4 passes through the motor holder 9, passes through the inner peripheral side of the motor shaft 22 of the lower motor 21, and reaches the space between the lower motor 21 and the upper motor 41. And the upper end portion of the drive shaft 4 is close to the upper end portion of the motor shaft 22 of the lower motor 21 and the lower end portion of the motor shaft 42 of the upper motor 41, respectively.

[0056] Also, the inner diameter of the motor shaft 22 of the lower motor 21 is set to a value larger than the outer diameter of the upper portion of the drive shaft 4. The upper portion of the drive shaft 4 is inserted into the motor shaft 22 in a state where its outer peripheral surface is separated from the inner peripheral surface of the motor shaft 22 of the lower motor 21. Therefore, the drive shaft 4 can rotate independently of the motor shaft 22 of the lower motor 21.

[0057] Note that the lower motor 21 is a specific example of the "first motor", the motor shaft 22 of the lower motor 21 is a specific example of the "first motor shaft", and the top motor bracket 27 of the lower motor 21 is a specific example of the "first motor bracket". Also, the upper motor 41 is a specific example of the "second motor", the motor shaft 42 of the upper motor 41 is a specific example of the "second motor shaft", and the bottom motor bracket 46 of the upper motor 41 is a specific example of the "second motor bracket". Further, the support member 85 is a specific example of the "fixing member".

[0058] (Power switching device) The power unit 2 includes a power switching device 61 that transmits either both or one of the power of the lower motor 21 and the power of the upper motor 41 to the drive shaft 4. By the power switching device 61, the method of rotating the propeller 3 can be switched between a method of rotating the propeller 3 by the combined force of the power of the lower motor 21 and the power of the upper motor 41, a method of rotating the propeller 3 only by the power of the lower motor 21 among the two motors of the power unit 2, and a method of rotating the propeller 3 only by the power of the upper motor 41 among the two motors of the power unit 2.

[0059] FIG. 7 shows a state of the power unit 2 when viewed from the left between the lower motor 21 and the upper motor 41. Note that in FIG. 7, each support member 85 is not shown. As shown in FIG. 7, the power switching device 61 is disposed between the lower motor 21 and the upper motor 41. The power switching device 61 includes a dog clutch 62, a lower fitted member 66, an upper fitted member 68, and a switching mechanism 71.

[0060] Figure 8(A) shows the dog clutch 62. The dog clutch 62 is a member that connects both or either one of the motor shaft 22 of the lower motor 21 and the motor shaft 42 of the upper motor 41 to the drive shaft 4. As shown in Figure 8(A), the dog clutch 62 is formed in a cylindrical shape. As shown in Figure 5, the dog clutch 62 is disposed between the upper end portion of the motor shaft 22 of the lower motor 21 and the lower end portion of the motor shaft 42 of the upper motor 41. Further, the dog clutch 62 is attached to the outer peripheral side of the upper end portion of the drive shaft 4 so as to be non-rotatable with respect to the drive shaft 4 and movable in the vertical direction with respect to the drive shaft 4.

[0061] On the upper part of the dog clutch 62, as shown in Figure 8(A), an upper fitting portion 64 is formed. Concavities and convexities are formed on the outer peripheral side of the upper fitting portion 64. Also, on the lower part of the dog clutch 62, a lower fitting portion 63 is formed. On the outer peripheral side of the lower fitting portion 63, concavities and convexities similar to those formed on the outer peripheral side of the upper fitting portion 64 are formed. Further, a clutch groove 65 is formed on the outer peripheral surface of the intermediate portion in the vertical direction of the dog clutch 62. The clutch groove 65 extends over the entire circumference of the dog clutch 62. Note that the dog clutch 62 is a specific example of the "connecting member", the lower fitting portion 63 is a specific example of the "first connecting portion", and the upper fitting portion 64 is a specific example of the "second connecting portion".

[0062] Figure 8(B) shows the lower fitted member 66. As shown in Figure 8(B), the lower fitted member 66 is formed in a cylindrical shape. Also, as shown in Figure 5, the lower fitted member 66 is fixed to the upper end portion of the motor shaft 22 of the lower motor 21 so as to be non-rotatable with respect to the motor shaft 22. Specifically, on the upper end portion of the motor shaft 22 of the lower motor 21, a fitted member insertion portion 22A is formed in which the inner diameter of the motor shaft 22 is enlarged compared to the inner diameters of other portions of the motor shaft 22. The lower part of the lower fitted member 66 is inserted into the fitted member insertion portion 22A and fixed in the fitted member insertion portion 22A by a method such as spline connection.

[0063] On the upper part of the lower fitting member 66, as shown in FIG. 8(B), a fitting portion 67 is formed. Concavities and convexities are formed on the inner peripheral side of the fitting portion 67. The shapes of the concavities and convexities of the lower fitting portion 63 of the dog clutch 62 and the shapes of the concavities and convexities of the fitting portion 67 of the lower fitting member 66 are set so that the lower fitting portion 63 can be fitted into the fitting portion 67.

[0064] The upper fitting member 68 is formed in a cylindrical shape and is fixedly attached to the lower end of the motor shaft 42 of the upper motor 41 so as not to rotate with respect to the motor shaft 42, as shown in FIG. 5. Specifically, a fitting member insertion portion 42A is formed at the lower end of the motor shaft 42 of the upper motor 41. The fitting member insertion portion 42A is a hole formed at the center of the lower end surface of the motor shaft 42. The upper part of the upper fitting member 68 is inserted into the fitting member insertion portion 42A and fixed within the fitting member insertion portion 42A by a method such as spline coupling.

[0065] A fitting portion 69 is formed at the lower part of the upper fitting member 68 (see FIG. 9(A)). Concavities and convexities are formed on the inner peripheral side of the fitting portion 69. The shapes of the concavities and convexities of the upper fitting portion 64 of the dog clutch 62 and the shapes of the concavities and convexities of the fitting portion 69 of the upper fitting member 68 are set so that the upper fitting portion 64 can be fitted into the fitting portion 69.

[0066] Note that two common fitting members can be used as the lower fitting member 66 and the upper fitting member 68. That is, one of the two common fitting members can be used as the lower fitting member 66 by fixing it within the fitting member insertion portion 22A of the motor shaft 22 of the lower motor 21 with its fitting portion facing upward, and the other of the two common fitting members can be used as the upper fitting member 68 by fixing it within the fitting member insertion portion 42A of the motor shaft 42 of the upper motor 41 with its fitting portion facing downward.

[0067] Figs. 9(A) to 9(C) show the operation of the dog clutch 62. In this embodiment, the dog clutch 62 can move vertically within a range of movement from a position where the lower fitting portion 63 of the dog clutch 62 is deeply fitted into the fitting portion 67 of the lower fitted member 66, as shown in Fig. 9(B), to a position where the upper fitting portion 64 of the dog clutch 62 is deeply fitted into the fitting portion 69 of the upper fitted member 68, as shown in Fig. 9(C).

[0068] As shown in Fig. 9(A), when the dog clutch 62 moves to the middle part within the above movement range, the lower fitting portion 63 of the dog clutch 62 engages with the fitting portion 67 of the lower fitted member 66, and the upper fitting portion 64 of the dog clutch 62 engages with the fitting portion 69 of the upper fitted member 68. As a result, the motor shaft 22 of the lower motor 21 and the drive shaft 4 are connected via the dog clutch 62, and at the same time, the motor shaft 42 of the upper motor 41 and the drive shaft 4 are connected via the dog clutch 62. Consequently, the power of both the lower motor 21 and the upper motor 41 is transmitted to the drive shaft 4, and the propeller 3 rotates by the combined force of the power of the lower motor 21 and the upper motor 41.

[0069] As shown in Fig. 9(B), when the dog clutch 62 moves to the lower part within the above movement range, the lower fitting portion 63 of the dog clutch 62 engages with the fitting portion 67 of the lower fitted member 66, and the engagement between the upper fitting portion 64 of the dog clutch 62 and the fitting portion 69 of the upper fitted member 68 is released. As a result, the motor shaft 22 of the lower motor 21 and the drive shaft 4 are connected via the dog clutch 62, and at the same time, the motor shaft 42 of the upper motor 41 and the drive shaft 4 are disconnected. Consequently, only the power of the lower motor 21 among the two motors of the power unit 2 is transmitted to the drive shaft 4, and the propeller 3 rotates by only the power of the lower motor 21.

[0070] As shown in Fig. 9(C), when the dog clutch 62 moves upward within the above-mentioned movement range, the upper fitting portion 64 of the dog clutch 62 fits with the fitting portion 69 of the upper fitting member 68, and the fitting between the lower fitting portion 63 of the dog clutch 62 and the fitting portion 67 of the lower fitting member 66 is released. As a result, the space between the motor shaft 42 of the upper motor 41 and the drive shaft 4 is connected via the dog clutch 62, and at the same time, the space between the motor shaft 22 of the lower motor 21 and the drive shaft 4 is disconnected. Consequently, among the two motors of the power unit 2, only the power of the upper motor 41 is transmitted to the drive shaft 4, and the propeller 3 rotates only by the power of the upper motor 41.

[0071] (Switching mechanism) Based on an external operation input, the power switching device 61 moves the dog clutch 62 in the vertical direction, thereby switching the connection modes of the motor shaft 22 of the lower motor 21, the motor shaft 42 of the upper motor 41, and the drive shaft 4 among (a) a mode in which both the motor shaft 22 of the lower motor 21 and the motor shaft 42 of the upper motor 41 are connected to the drive shaft 4, (b) a mode in which the motor shaft 22 of the lower motor 21 is connected to the drive shaft 4 and the motor shaft 42 of the upper motor 41 is not connected to the drive shaft 4, and (c) a mode in which the motor shaft 42 of the upper motor 41 is connected to the drive shaft 4 and the motor shaft 22 of the lower motor 21 is not connected to the drive shaft 4. In the mode (a) above, the propeller 3 can be rotated by the combined power of the lower motor 21 and the upper motor 41. Also, in the mode (b) above, among the two motors of the power unit 2, the propeller 3 can be rotated only by the power of the lower motor 21. Further, in the mode (c) above, among the two motors of the power unit 2, the propeller 3 can be rotated only by the power of the upper motor 41.

[0072] As shown in Fig. 7, the switching mechanism 71 is arranged at the front part within the space between the lower motor 21 and the upper motor 41.

[0073] Figure 8(C) shows the disassembled switching mechanism 71. As shown in Figure 8(C), the switching mechanism 71 includes a clutch cam shaft 72, a fork unit 74, a clutch rod 80, and a link mechanism 81.

[0074] The clutch cam shaft 72 is a shaft extending in the vertical direction. The clutch cam shaft 72 has a cylindrical cam structure, and a cam groove 73 for converting the rotation of the clutch cam shaft 72 into the vertical movement of the fork unit 74 is formed on the outer peripheral surface of the middle part of the clutch cam shaft 72 in the vertical direction.

[0075] The fork unit 74 is attached to the outer peripheral side of the clutch cam shaft 72 so as to be movable in the vertical direction with respect to the clutch cam shaft 72. The fork unit 74 has a cylindrical portion 75 and a driven pin 76. The middle part of the clutch cam shaft 72 in the vertical direction is inserted into the inner peripheral side of the cylindrical portion 75. Further, the driven pin 76 is inserted into a pin hole 75A formed in the cylindrical portion 75. The driven pin 76 penetrates through the pin hole 75A, and the tip of the driven pin 76 is inserted into the cam groove 73 inside the cylindrical portion 75. The driven pin 76 inserted into the pin hole 75A is fixed to the cylindrical portion 75 by a stopper member 78 with a coil spring 77 interposed therebetween. With this configuration, the fork unit 74 moves in the vertical direction according to the rotation of the clutch cam shaft 72. Further, the fork unit 74 has a fork 79. The fork 79 is integrally formed with the cylindrical portion 75. The fork 79 protrudes radially outward from the outer peripheral surface of the cylindrical portion 75. The tip of the fork 79 is bifurcated.

[0076] As shown in FIG. 7, the clutch camshaft 72 to which the fork unit 74 is attached is rotatably supported between the outer peripheral portion of the lower motor 21 and the outer peripheral portion of the upper motor 41. Specifically, a camshaft support portion 29 is provided at the left front portion of the top motor bracket 27 of the lower motor 21. The lower end portion of the clutch camshaft 72 is rotatably supported by the camshaft support portion 29 via a bearing, for example. Also, a camshaft support portion 48 is provided at the left front portion of the bottom motor bracket 46 of the upper motor 41. The upper end portion of the clutch camshaft 72 is rotatably supported by the camshaft support portion 48 via a bearing, for example.

[0077] Also, the fork 79 of the fork unit 74 grips the outer peripheral portion of the dog clutch 62 with the bifurcated tip portions thereof. Specifically, the tip portions of the fork 79 of the fork unit 74 are inserted into the clutch groove 65 of the dog clutch 62 as shown in FIGS. 6 and 7. The tip portions of the fork 79 are inserted into the clutch groove 65 with a gap therebetween. Thereby, the dog clutch 62 can rotate as the drive shaft 4 rotates with the tip portions of the fork 79 inserted into the clutch groove 65.

[0078] As shown in FIG. 8(C), the clutch rod 80 is a rod extending in the vertical direction. As shown in FIG. 4, the clutch rod 80 is rotatably supported between the outer peripheral portion of the lower motor 21 and the outer peripheral portion of the upper motor 41. Specifically, a rod support portion 28 is provided at the right front portion of the top motor bracket 27 of the lower motor 21. The lower end portion of the clutch rod 80 is rotatably supported by the rod support portion 28 via a bearing, for example. Also, a rod support portion 47 is provided at the right front portion of the bottom motor bracket 46 of the upper motor 41. The upper end portion of the clutch rod 80 is rotatably supported by the rod support portion 47 via a bearing, for example.

[0079] As shown in FIG. 6, the link mechanism 81 is a mechanism that connects between the clutch cam shaft 72 and the clutch rod 80 and transmits the rotation of the clutch rod 80 to the clutch cam shaft 72. As shown in FIG. 8(C), the link mechanism 81 includes a first link member 81A, a second link member 81B, and a third link member 81C. One end of the first link member 81A is connected to the clutch rod 80 in a non-rotatable manner with respect to the clutch rod 80. One end of the second link member 81B is connected to the clutch cam shaft 72 in a non-rotatable manner with respect to the clutch cam shaft 72. One end of the third link member 81C is rotatably connected to the other end of the first link member 81A with respect to the first link member 81A. The other end of the third link member 81C is rotatably connected to the other end of the second link member 81B with respect to the second link member 81B.

[0080] In FIG. 8(C), when the clutch rod 80 rotates in the direction of arrow A, the rotation is transmitted to the clutch cam shaft 72 via the link mechanism 81, and the clutch cam shaft 72 rotates in the direction of arrow C. Due to the rotation of this clutch cam shaft 72, the fork unit 74 moves upward, for example. On the other hand, when the clutch rod 80 rotates in the direction of arrow B, the rotation is transmitted to the clutch cam shaft 72 via the link mechanism 81, and the clutch cam shaft 72 rotates in the direction of arrow D. Due to the rotation of this clutch cam shaft 72, the fork unit 74 moves downward, for example. Note that the relationship between the rotation direction of the clutch rod 80 and the moving direction of the fork unit 74 in the vertical direction, and the relationship between the rotation amount of the clutch rod 80 and the moving amount of the fork unit 74 in the vertical direction can be set according to the shape of the cam groove 73 formed in the clutch cam shaft 72.

[0081] Since the outer peripheral portion of the dog clutch 62 is gripped by the fork 79 of the fork unit 74, when the fork unit 74 moves upward, the dog clutch 62 moves upward. Also, when the fork unit 74 moves downward, the dog clutch 62 moves downward.

[0082] Further, the clutch rod 80 rotates by receiving switching power for switching the connection modes of the motor shaft 22, the motor shaft 42, and the drive shaft 4. Although not shown, an actuator (for example, a DC motor) is provided at the upper part of the outboard motor 1, and the output shaft of the actuator is connected to the clutch rod 80. An external operation input is input to the actuator. Based on the external operation input, the actuator operates, the clutch rod 80 rotates by receiving the rotational power output from the output shaft of the actuator, and the dog clutch 62 moves in the vertical direction according to the rotation of the clutch rod 80.

[0083] Note that the clutch cam shaft 72 is a specific example of the "switching shaft", and the cam groove 73 is a specific example of the "cam". Further, the fork unit 74 is a specific example of the "driven member", and the fork 79 is a specific example of the "gripping part". Also, the clutch rod 80 is a specific example of the "input rod".

[0084] As described above, in the power unit 2 of the outboard motor 1 according to the embodiment of the present invention, the lower motor 21 and the upper motor 41 are arranged in the vertical direction such that the respective motor shafts 22 and 42 extend in the vertical direction. Further, a dog clutch 62 that connects either or both of the upper end portion of the motor shaft 22 of the lower motor 21 and the lower end portion of the motor shaft 42 of the upper motor 41 to the drive shaft 4 is disposed between the lower motor 21 and the upper motor 41. Furthermore, a switching mechanism 71 that switches the connection mode of the motor shaft 22, the motor shaft 42, and the drive shaft 4 by moving the dog clutch 62 is disposed between the lower motor 21 and the upper motor 41. With the above configuration, even when an outboard motor is provided with two motors and a mechanism for switching the method of rotating the propeller, it is possible to prevent the outboard motor from becoming significantly larger in size. Specifically, since the lower motor 21 and the upper motor 41 are arranged in the vertical direction such that the respective motor shafts 22 and 42 extend in the vertical direction, the upper end portion of the motor shaft 22 of the lower motor 21 and the lower end portion of the motor shaft 42 of the upper motor 41 can be brought closer to each other. Then, by disposing the dog clutch 62 and the switching mechanism 71 between the lower motor 21 and the upper motor 41, the upper end portion of the motor shaft 22 of the lower motor 21, the lower end portion of the motor shaft 42 of the upper motor 41, the dog clutch 62, and the switching mechanism 71 can be concentrated between the lower motor 21 and the upper motor 41. Furthermore, by concentrating the upper end portion of the motor shaft 22, the lower end portion of the motor shaft 42, the dog clutch 62, and the switching mechanism 71, the dog clutch 62 and the switching mechanism 71 can be formed in a compact manner. As a result, a small power unit 2 having two motors can be formed, and thus, it is possible to prevent the outboard motor 1 from becoming significantly larger in size compared to an outboard motor having only one motor.

[0085] Moreover, according to the outboard motor 1 of the present embodiment, the method of rotating the propeller 3 can be switched between a method of rotating the propeller 3 by the combined power of the power of the lower motor 21 and the power of the upper motor 41, a method of rotating the propeller 3 only by the power of the lower motor 21 among the two motors of the power unit 2, and a method of rotating the propeller 3 only by the power of the upper motor 41 among the two motors of the power unit 2. Therefore, the performance of the outboard motor can be improved. Specifically, the output of the power unit 2 can be significantly changed according to the navigation situation of the ship, etc., and the electricity cost of the power unit 2 can be adjusted. For example, by switching the method of rotating the propeller 3 from a method of rotating the propeller 3 only by the power of one of the lower motor 21 and the upper motor 41 to a method of rotating the propeller 3 by the combined power of the power of the lower motor 21 and the power of the upper motor 41, the output of the power unit 2 can be significantly increased. Also, by switching from a method of rotating the propeller 3 by the combined power of the power of the lower motor 21 and the power of the upper motor 41 to a method of rotating the propeller 3 only by the power of one of the lower motor 21 and the upper motor 41, the electricity cost of the power unit 2 can be reduced. Further, for example, when one of the lower motor 21 and the upper motor 41 fails during navigation, the failed motor is disconnected from the drive shaft 4, and the non-failed motor is connected to the drive shaft 4. Thereby, the propeller 3 can be rotated only by the power of the non-failed motor to move the ship.

[0086] Further, in the outboard motor 1 of the present embodiment, the switching mechanism 71 includes a clutch cam shaft 72 rotatably supported between the outer peripheral side portion of the lower motor 21 and the outer peripheral side portion of the upper motor 41, a fork unit 74 that moves in the vertical direction in response to the rotation of the clutch cam shaft 72, and a cam groove 73 that converts the rotation of the clutch cam shaft 72 into the vertical movement of the fork unit 74. The fork unit 74 is provided with a fork 79 that grips the outer peripheral portion of the dog clutch 62. Thereby, a switching mechanism 71 that moves the dog clutch 62 in the vertical direction can be realized by a simple mechanism.

[0087] Also, in the outboard motor 1 of the present embodiment, the upper motor 41 is firmly fixed to the lower motor 21 by a plurality of support members 85. The lower end portion of the clutch cam shaft 72 is rotatably supported by the top motor bracket 27 of the lower motor 21, and the upper end portion of the clutch cam shaft 72 is rotatably supported by the bottom motor bracket 46 of the upper motor 41. In this way, by supporting both ends of the clutch cam shaft 72 between the lower motor 21 and the upper motor 41 that are firmly fixed to each other, the structure for rotatably supporting the clutch cam shaft 72 can be made strong, displacement or inclination of the clutch cam shaft 72 can be suppressed, and the durability of the clutch cam shaft 72 can be enhanced. Further, by using the top motor bracket 27 and the bottom motor bracket 46 for supporting the clutch cam shaft 72, the support structure of the clutch cam shaft 72 can be formed compactly, and the number of parts for forming the support structure of the clutch cam shaft 72 can be reduced.

[0088] Further, in the outboard motor 1 of the present embodiment, the switching mechanism 71 includes a clutch rod 80 to which the output shaft of the actuator is connected and which rotates by receiving the rotational power output from the output shaft of the actuator, and a link mechanism 81 that transmits the rotation of the clutch rod 80 to the clutch camshaft 72 to rotate the clutch camshaft 72. The link mechanism 81 includes a first link member 81A, a second link member 81B, and a third link member 81C. With this configuration, the rotation amount of the clutch camshaft 72 with respect to the rotation amount of the output shaft of the actuator can be set by the ratio of the length of the first link member 81A to the length of the second link member 81B, so that the degree of freedom of the setting increases. Also, by making the first link member 81A longer than the second link member 81B, the output torque of the actuator for rotating the clutch camshaft 72 can be reduced. As a result, it becomes possible to employ a small-sized actuator with a small output as the actuator for rotating the clutch camshaft 72. Therefore, miniaturization and weight reduction of the power unit 2 can be promoted.

[0089] Further, according to the outboard motor 1 of the present embodiment, since the upper motor 41 is fixed to the lower motor 21 fixed to the motor holder 9, the number of parts for fixing the two motors to the outboard motor 1 can be reduced, and miniaturization and weight reduction of the outboard motor 1 can be achieved.

[0090] Also, in the outboard motor 1 of the present embodiment, the switching mechanism 71 is disposed at the front part in the space between the lower motor 21 and the upper motor 41. With this configuration, when performing maintenance or repair of the switching mechanism 71, the top cover 12 can be removed, and maintenance or repair of the switching mechanism 71 can be easily performed from the ship side.

[0091] In the above embodiment, the switching mechanism 71 switches the connection modes of the motor shaft 22 of the lower motor 21, the motor shaft 42 of the upper motor 41, and the drive shaft 4 among (a) a mode in which both the motor shaft 22 of the lower motor 21 and the motor shaft 42 of the upper motor 41 are connected to the drive shaft 4, (b) a mode in which the motor shaft 22 of the lower motor 21 is connected to the drive shaft 4 and the motor shaft 42 of the upper motor 41 is not connected to the drive shaft 4, and (c) a mode in which the motor shaft 42 of the upper motor 41 is connected to the drive shaft 4 and the motor shaft 22 of the lower motor 21 is not connected to the drive shaft 4. However, the present invention is not limited to this. The switching of the connection modes of the motor shaft 22, the motor shaft 42, and the drive shaft 4 by the switching mechanism 71 may be performed only between (a) and (b) above, only between (a) and (c) above, or only between (b) and (c) above.

[0092] In the above embodiment, the lower motor 21 and the upper motor 41 having the same performance regarding power generation such as output and torque are provided in the power unit 2. However, the performance regarding power generation such as output and torque may be made different between the lower motor 21 and the upper motor 41.

[0093] In the above embodiment, an example is given in which the lower fitting member 66 is fixed to the upper end portion of the motor shaft 22 of the lower motor 21 to provide a fitting portion that fits with the fitting portion of the dog clutch above the motor shaft 22. However, the present invention is not limited to this. For example, a fitting portion that fits with the fitting portion of the dog clutch may be integrally formed at the upper end portion of the motor shaft 22. Similarly, for the motor shaft 42 of the upper motor 41, a fitting portion that fits with the fitting portion of the dog clutch may be integrally formed at the lower end portion of the motor shaft 42.

[0094] Also, the type of motor used in the power unit in the present invention is not limited, and for example, a DC motor may be used. Further, the present invention can also be applied to marine propulsion devices other than outboard motors.

[0095] Further, the present invention can be appropriately modified within a range not contrary to the gist or idea of the invention that can be read from the claims and the entire specification, and a marine propulsion unit with such modifications is also included in the technical idea of the present invention.

Explanation of Reference Numerals

[0096] 1 Outboard motor (marine propulsion unit) 2 Power unit 3 Propeller 4, 131, 231, 331 Drive shaft 5 Propeller shaft 21 Lower motor (first motor) 22 Motor shaft (first motor shaft) 27 Top motor bracket (first motor bracket) 41 Upper motor (second motor) 42 Motor shaft (second motor shaft) 46 Bottom motor bracket (second motor bracket) 61 Power switching device 62 Dog clutch (connecting member) 63 Lower fitting portion (first connecting portion) 64 Upper fitting portion (second connecting portion) 71 Switching mechanism 72 Clutch cam shaft (switching shaft) 73 Cam groove (cam) 74 Fork unit (driven member) 79 Fork (holding portion) 80 Clutch rod (input rod) 81 Link mechanism 81A First link member 81B Second link member 81C Third link member 85 Strut member (fixed member) 111, 211, 311 First motor 112, 212, 312 First motor shaft 121, 221, 321 Second motor 122, 222, 322 Second motor shaft 141, 241, 341 Connecting member 145, 245, 345 First connection part 146, 246, 346 Second connection part

Claims

1. A marine propulsion unit comprising a power unit that generates power, a propeller shaft to which a propeller is fixed, and a drive shaft provided between the power unit and the propeller shaft for transmitting the power generated by the power unit to the propeller shaft, wherein the power unit comprises a first motor having a first motor shaft extending in the vertical direction, a second motor disposed above the first motor and having a second motor shaft extending in the vertical direction, a connecting member movably disposed in the vertical direction between the first motor and the second motor, with a first connecting portion provided at the lower end for connecting itself to the upper end of the first motor shaft and a second connecting portion provided at the upper end for connecting itself to the lower end of the second motor shaft, and a switching mechanism disposed between the first motor and the second motor for switching the connection mode of the first motor shaft, the second motor shaft, and the drive shaft among at least any two of the following modes: (a) a mode in which both the first motor shaft and the second motor shaft are connected to the drive shaft; (b) a mode in which the first motor shaft is connected to the drive shaft and the second motor shaft is not connected to the drive shaft; and (c) a mode in which the second motor shaft is connected to the drive shaft and the first motor shaft is not connected to the drive shaft. The marine propulsion unit is characterized by this.

2. The switching mechanism comprises a switching shaft rotatably supported between an outer peripheral portion of the first motor and an outer peripheral portion of the second motor, a driven member that moves in the vertical direction in response to rotation of the switching shaft, and a cam that converts the rotation of the switching shaft into the vertical movement of the driven member, wherein a gripping portion for gripping an outer peripheral portion of the connecting member is provided on the driven member, and the connecting member moves in the vertical direction as the driven member moves in the vertical direction. The marine propulsion unit according to Claim 1 is characterized by this.

3. The power unit is provided with a fixing member for fixing the second motor to the first motor. The second motor is supported by the fixed member at a position above the first motor and away from the first motor. The lower end of the switching shaft is rotatably supported by a first motor bracket provided on the upper part of the first motor, and the upper end of the switching shaft is rotatably supported by a second motor bracket provided on the lower part of the second motor. The marine propulsion device according to claim 2, characterized in that.

4. The switching mechanism is An input rod that is rotatably supported by the first motor bracket and the second motor bracket, and rotates in response to switching power input to the switching mechanism to perform switching between the at least two modes. The marine propulsion device according to claim 3, further comprising a link mechanism that transmits the rotation of the input rod to the switching shaft to rotate the switching shaft.

5. The link mechanism is A first link member having one end connected to the input rod in a non-rotatable manner with respect to the input rod. A second link member having one end connected to the switching shaft in a non-rotatable manner with respect to the switching shaft. The marine propulsion device according to claim 4, further comprising a third link member having one end rotatably connected to the other end of the first link member with respect to the first link member, and the other end rotatably connected to the other end of the second link member with respect to the second link member.

6. The marine propulsion device according to claim 1, characterized in that the switching mechanism is arranged at the front part in the space between the first motor and the second motor.

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