Marine propulsion device

Abstract

To simplify and miniaturize a structure for transmitting power of two power sources to a propeller, in a ship propulsion machine having the two power sources for rotating the propeller.SOLUTION: The marine propulsion device includes an engine that is a first power source that rotates the propeller, a motor that is a second power source that rotates the propeller, an engine drive shaft 13 connected to the engine, a motor drive shaft 14 connected to the motor, an upper transmission shaft 17 connected to the propeller shaft, and a dog clutch 40 that switches a connection mode of the engine drive shaft 13, the motor drive shaft 14, and the upper transmission shaft 17 between a mode in which the engine drive shaft 13 and the upper transmission shaft 17 are connected to each other and a mode in which the motor drive shaft 14 and the upper transmission shaft 17 are connected to each other.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a boat propulsion device equipped with two power sources that rotate propellers. [Background technology]

[0002] One type of marine propulsion device equipped with two power sources to rotate the propeller is a hybrid marine propulsion device that has an engine and a motor and generates propulsive force for the marine vessel by rotating the propeller using the power of the engine and the power of the motor.

[0003] Japanese Patent Laid-Open Publication No. 2007-8329 (Patent Document 1) describes a hybrid outboard motor. The outboard motor described in this publication includes an engine, a motor, a driving force adjustment unit, and a drive shaft that transmits power output from the driving force adjustment unit to a propeller shaft. The driving force adjustment unit includes a differential gear unit that combines engine power and motor power, and a centrifugal clutch that transmits the engine power to the differential gear unit when the engine speed is equal to or greater than a set value and prevents the engine power from being transmitted to the differential gear unit otherwise. The engine and motor speeds increase and decrease depending on the amount of operation of the throttle grip on the steering handle. When the engine speed is below a set value, only the motor power is output to the drive shaft via the differential gear unit. As a result, the propeller rotates solely due to the motor power. On the other hand, when the engine speed is equal to or greater than the set value, the engine power and the motor power are combined by the differential gear unit and output to the drive shaft. As a result, the propeller rotates using both the engine power and the motor power. With the outboard motor described in this publication, when trolling, the boat can move at an extremely slow speed by generating propulsive force using only the motor power. When moving the boat at high speed, the boat can move at high speed by generating propulsive force using both the engine power and the motor power, thereby achieving low fuel consumption of the engine. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-8329 Summary of the Invention [Problem to be solved by the invention]

[0005] The outboard motor of the above publication uses a differential gear unit to combine engine power and motor power and output the combined power to the drive shaft. Differential gear units generally have a complex structure and are difficult to miniaturize. Therefore, if emphasis is placed on preventing the size of a marine propulsion unit from increasing, it is difficult to incorporate a differential gear unit into the marine propulsion unit.

[0006] Furthermore, the outboard motor in the above publication uses a centrifugal clutch as a device for switching between generating propulsive force using only motor power and generating propulsive force using both engine power and motor power. Generally, centrifugal clutches become larger as torque capacity increases. Therefore, when a high-horsepower engine is installed in a marine propulsion unit, the centrifugal clutch becomes larger, making it difficult to secure space within the marine propulsion unit for installing the centrifugal clutch.

[0007] The present invention has been made in consideration of problems such as those described above, and an object of the present invention is to provide a marine propulsion device equipped with two power sources that rotate propellers, which can simplify and compact the structure that transmits the power of the two power sources to the propellers. [Means for solving the problem]

[0008] In order to solve the above problem, the marine propulsion device of the present invention is characterized by comprising a propeller, a first power source that rotates the propeller, a second power source that rotates the propeller, a propeller shaft on which the propeller is mounted, a first drive shaft connected to the first power source, a second drive shaft connected to the second power source, a transmission shaft connected to the propeller shaft, and a dog clutch that switches the connection modes of the first drive shaft, the second drive shaft, and the transmission shaft between at least two of a first mode in which the first drive shaft and the transmission shaft are connected to each other, a second mode in which the second drive shaft and the transmission shaft are connected to each other, and a third mode in which both the first drive shaft and the second drive shaft are connected to the transmission shaft. [Effects of the Invention]

[0009] According to the present invention, in a marine propulsion device equipped with two power sources that rotate propellers, the structure that transmits the power of the two power sources to the propellers can be simplified and made compact. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is an explanatory diagram showing the configuration of a marine propulsion device according to a first embodiment of the present invention. [Figure 2] 2 is an enlarged cross-sectional view of the power switching mechanism in the marine vessel propulsion device in FIG. 1 in a state where the dog clutch is moved upward. [Figure 3] 2 is an enlarged cross-sectional view of the power switching mechanism in the marine vessel propulsion device in FIG. 1 in a state where the dog clutch is moved downward. [Figure 4] FIG. 3 is a cross-sectional view showing the main components of the power switching mechanism in FIG. 2. [Figure 5] 3 is a cross-sectional view showing the power switching mechanism taken along the direction of arrows VV in FIG. 2 as viewed from the front. [Figure 6]FIG. 6 is an explanatory diagram showing a power switching mechanism in a marine propulsion device according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0011] A marine propulsion device according to an embodiment of the present invention includes a propeller, a first power source that rotates the propeller, a second power source that rotates the propeller, a propeller shaft on which the propeller is mounted, a first drive shaft connected to the first power source, a second drive shaft connected to the second power source, a transmission shaft connected to the propeller shaft, and a dog clutch that switches the connection state of the first drive shaft, the second drive shaft, and the transmission shaft.

[0012] The dog clutch switches the connection state of the first drive shaft, the second drive shaft, and the transmission shaft between at least two of a first state in which the first drive shaft and the transmission shaft are connected to each other, a second state in which the second drive shaft and the transmission shaft are connected to each other, and a third state in which both the first drive shaft and the second drive shaft are connected to each other and the transmission shaft.

[0013] In the marine propulsion device of this embodiment, when the connection mode of the first drive shaft, the second drive shaft, and the transmission shaft is switched to the first mode by the dog clutch, only the power of the first power source of the first and second power sources is transmitted to the propeller shaft, and the propeller rotates only by the power of the first power source.Furthermore, when the connection mode of the first drive shaft, the second drive shaft, and the transmission shaft is switched to the second mode by the dog clutch, only the power of the second power source of the first and second power sources is transmitted to the propeller shaft, and the propeller rotates only by the power of the second power source. Furthermore, when the connection mode of the first drive shaft, the second drive shaft, and the transmission shaft is switched to the third mode by the dog clutch, both the power of the first power source and the power of the second power source are transmitted to the propeller shaft, and the propeller rotates by the power of the first power source and the power of the second power source. Thus, according to the marine propulsion device of this embodiment, the dog clutch can switch the power source that rotates the propeller, thereby achieving a function equivalent to that of the centrifugal clutch in the conventional marine propulsion device described above. Furthermore, the centrifugal clutch has a weight that switches between engagement and disengagement of the clutch using centrifugal force. For example, due to such structural reasons, centrifugal clutches become larger as the torque capacity increases. In contrast, a dog clutch does not require such a weight, and therefore, compared to a centrifugal clutch, its structure makes it easier to prevent the size from increasing as the torque capacity increases.

[0014] Furthermore, in the marine propulsion device of this embodiment, when the connection mode of the first drive shaft, the second drive shaft, and the transmission shaft is switched to the third mode by the dog clutch, the power of the first power source and the power of the second power source are transmitted to the propeller shaft, and the propeller rotates due to the power of the first power source and the power of the second power source. Thus, according to the marine propulsion device of this embodiment, the dog clutch can combine the power of the first power source and the power of the second power source and output it to the propeller shaft, thereby achieving functionality equivalent to that of the differential gear unit in the conventional marine propulsion device. Furthermore, differential gear units have a complex structure with many mechanical elements (gears, etc.), making it difficult to reduce the size of differential gear units. In contrast, a dog clutch can be configured with fewer mechanical elements than a differential gear unit, making it easier to simplify the structure and reduce the size compared to a differential gear unit.

[0015] In this way, in the marine propulsion device of this embodiment, switching between the power sources that rotate the propellers can be performed using a dog clutch, which is easier to keep down in size compared to a centrifugal clutch, and combining the power of the two power sources can be performed using a dog clutch, which is easier to simplify and downsize in structure compared to a differential gear device. Therefore, the marine propulsion device of this embodiment makes it possible to simplify and downsize the structure that transmits the power of the two power sources to the propellers. [Example]

[0016] Two embodiments of the present invention will be described below with reference to the drawings. In the description of each embodiment, the directions of up (Ud), down (Dd), front (Fd), back (Bd), left (Ld), and right (Rd) refer to the arrows at the bottom right of Figures 1 to 3, 5, and 6.

[0017] (Ship propulsion system) 1 shows a boat propulsion device 1 according to a first embodiment of the present invention. The boat propulsion device 1 is a device that generates propulsive force for a boat. The boat propulsion device 1 of this embodiment is an outboard motor that is attached to a boat.

[0018] As shown in FIG. 1, the marine propulsion unit 1 employs contra-rotating propellers. The marine propulsion unit 1 includes two propellers 2 and 3, a propeller shaft 4 on which the propeller 2 is mounted, and a propeller shaft 5 on which the propeller 3 is mounted. The propellers 2 and 3 and the propeller shafts 4 and 5 are disposed at the bottom of the marine propulsion unit 1 and are positioned below the water surface when the marine propulsion unit 1 is attached to the marine vessel. The propeller shafts 4 and 5 each extend in the fore-and-aft direction. The propeller shafts 4 and 5 are also disposed coaxially with each other. The propeller shaft 5 is formed in a cylindrical shape, and the propeller shaft 4 is inserted into the propeller shaft 5. The propeller shafts 4 and 5 can rotate independently of each other. The propellers 2 and 3 are also arranged in the fore-and-aft direction. The rear propeller 2 is fixed to the rear end of the propeller shaft 4 and rotates integrally with the propeller shaft 4. The front propeller 3 is fixed to the rear end of the propeller shaft 5 and rotates integrally with the propeller shaft 5.

[0019] The marine propulsion device 1 also includes an engine (internal combustion engine) 6 which is a first power source that rotates both of the propellers 2 and 3, a motor (electric motor) 8 which is a second power source that rotates both of the propellers 2 and 3, an engine drive shaft 13 connected to the engine 6, a motor drive shaft 14 connected to the motor 8, and a transmission shaft 16 connected to the propeller shafts 4 and 5. The transmission shaft 16 is divided into an upper transmission shaft 17 and a lower transmission shaft 18. The engine drive shaft 13 is a specific example of a "first drive shaft," and the motor drive shaft 14 is a specific example of a "second drive shaft."

[0020] Furthermore, the marine propulsion unit 1 is equipped with a power switching mechanism 31 that switches the power source that rotates the propellers 2 and 3, a rotation direction switching mechanism 21 that switches the rotation direction of the propellers 2 and 3, and a rotation transmission mechanism 26 that transmits the rotation of the lower transmission shaft 18 to the two propeller shafts 4 and 5.

[0021] The engine 6 and motor 8 are disposed at the top of the marine vessel propulsion device 1 and are positioned above the water surface when the marine vessel propulsion device 1 is attached to the marine vessel. The engine 6 is disposed so that the extension direction of the crankshaft 7 is in the vertical direction. The engine 6 is also disposed so that the part of the engine 6 where the crankshaft 7 is provided is at the front of the marine vessel propulsion device 1. The engine drive shaft 13 extends in the vertical direction. The crankshaft 7 is connected to the upper end of the engine drive shaft 13 via an engine drive gear 11 and an engine driven gear 12. As a result, the rotation of the crankshaft 7 is transmitted to the engine drive shaft 13.

[0022] The motor 8 is disposed below and rearward of the engine 6, with the extension direction of the output shaft 9 (extension direction of the rotor's rotation axis) aligned with the front-to-rear direction. The motor drive shaft 14 also extends in the front-to-rear direction. The rear end of the motor drive shaft 14 is connected to the output shaft 9 of the motor 8. A motor drive gear 15 is provided at the front end of the motor drive shaft 14. The motor drive gear 15 is a bevel gear. The motor drive gear 15 is fixed to the front end of the motor drive shaft 14 so that it cannot rotate relative to the motor drive shaft 14. The motor drive shaft 14 and the motor drive gear 15 rotate integrally with the output shaft 9. The motor drive gear 15 is a specific example of a "second gear."

[0023] The power switching mechanism 31 is disposed below the engine drive shaft 13 and in front of the motor drive shaft 14. The power switching mechanism 31 includes a dog clutch 40 and a one-way clutch 51. When the dog clutch 40 moves upward in the power switching mechanism 31, the engine drive shaft 13 and the upper transmission shaft 17 are connected to each other via the dog clutch 40, and the rotation of the engine drive shaft 13 is transmitted to the upper transmission shaft 17 via the dog clutch 40. On the other hand, when the dog clutch 40 moves downward, the motor drive shaft 14 and the upper transmission shaft 17 are connected to each other via the dog clutch 40, and the rotation of the motor drive shaft 14 is transmitted to the upper transmission shaft 17 via the dog clutch 40. When the dog clutch 40 moves upward and the rotation speed in a predetermined direction of a transmission gear 45 (described below) is higher than the rotation speed in the predetermined direction of the upper transmission shaft 17, the rotation of the motor drive shaft 14 is transmitted to the upper transmission shaft 17 via the one-way clutch 51. The power switching mechanism 31 will be described in detail later.

[0024] The upper transmission shaft 17 and the lower transmission shaft 18 each extend in the vertical direction and are arranged coaxially with the engine drive shaft 13. The upper end of the upper transmission shaft 17 is connected to the output side of the power switching mechanism 31. The lower transmission shaft 18 is arranged below the upper transmission shaft 17. A rotation direction switching mechanism 21 is arranged between the upper transmission shaft 17 and the lower transmission shaft 18.

[0025] The rotation direction switching mechanism 21 includes three gears 22, 23, and 24, and a rotation direction switching clutch 25. The gears 22, 23, and 24 are all bevel gears. The gear 22 is provided at the lower end of the upper transmission shaft 17. The gear 22 is fixed to the upper transmission shaft 17 and rotates integrally therewith. The gear 23 is provided on the outer periphery of the upper part of the lower transmission shaft 18. The gear 23 is not fixed to the lower transmission shaft 18. The lower transmission shaft 18 passes through a hole provided in the center of the gear 23, and the outer periphery of the lower transmission shaft 18 does not contact the inner periphery of the hole in the gear 23. Therefore, the gear 23 can rotate relative to the lower transmission shaft 18. The gear 24 is engaged with both the gear 22 and the gear 23. The rotation of the gear 22 is transmitted to the gear 23 via the gear 24. Furthermore, both gear 22 and gear 23 rotate about axis A in FIG. 1 , but due to the meshing structure of gears 22, 23, and 24, the rotational direction of gear 22 and the rotational direction of gear 23 are opposite to each other. Furthermore, rotational direction-switching clutch 25 is structurally a dog clutch. Rotational direction-switching clutch 25 is mounted on the upper end of lower transmission shaft 18 and is immovable relative to lower transmission shaft 18 but movable up and down relative to lower transmission shaft 18. When rotational direction-switching clutch 25 moves upward, gear 22 and lower transmission shaft 18 are connected to each other via rotational direction-switching clutch 25. As a result, the rotation of gear 22, i.e., the rotation of upper transmission shaft 17, is transmitted to lower transmission shaft 18 only via rotational direction-switching clutch 25, so that the rotational direction of lower transmission shaft 18 becomes the same as the rotational direction of upper transmission shaft 17. On the other hand, when the rotation direction switching clutch 25 moves downward, the gear 23 and the lower transmission shaft 18 are connected to each other via the rotation direction switching clutch 25. As a result, the rotation of the gear 22, i.e., the rotation of the upper transmission shaft 17, is transmitted to the lower transmission shaft 18 via the gear 24, the gear 23, and the rotation direction switching clutch 25, so that the rotation direction of the lower transmission shaft 18 becomes opposite to that of the upper transmission shaft 17.In this way, with the rotation direction switching mechanism 21, the rotation direction of the lower transmission shaft 18 can be switched relative to the rotation direction of the upper transmission shaft 17 by moving the rotation direction switching clutch 25. Since the rotation direction of each of the propellers 2, 3 is determined by the rotation direction of the lower transmission shaft 18, the rotation direction of each of the propellers 2, 3 can be switched by switching the rotation direction of the lower transmission shaft 18. And, by switching the rotation direction of each of the propellers 2, 3, the boat can be switched between forward and reverse.

[0026] The rotation transmission mechanism 26 is disposed below the lower transmission shaft 18. The rotation transmission mechanism 26 includes a gear 27, a gear 28, and a gear 29. The gears 27, 28, and 29 are all bevel gears. The gear 27 is fixed to the lower end of the lower transmission shaft 18 and rotates integrally therewith. The gear 28 is fixed to the front end of the propeller shaft 4 and rotates integrally therewith. The gear 29 is fixed to the front end of the propeller shaft 5 and rotates integrally therewith. The gear 28 is disposed in front of the gear 27, and the gear 29 is disposed behind the gear 27. The gears 28 and 29 are each meshed with the gear 27, and the rotation of the gear 27 is transmitted to the gears 28 and 29, respectively. 1, but due to the meshing structure of gears 27, 28, and 29, the rotational direction of gear 28 is opposite to that of gear 29. As a result, when gear 27, i.e., lower transmission shaft 18, rotates, propeller shaft 4 and propeller shaft 5 rotate in opposite directions, and therefore the two propellers 2 and 3 that make up the contra-rotating propellers rotate in opposite directions.

[0027] (Configuration of power switching mechanism) Fig. 2 shows the power switching mechanism 31 with the dog clutch 40 moved up. Fig. 3 shows the power switching mechanism 31 with the dog clutch 40 moved down. Fig. 4 shows the main components of the power switching mechanism 31 separated from each other.

[0028] 2 and 4, the power switching mechanism 31 includes an engagement member 32, a clutch shaft 36, a dog clutch 40, a transmission gear 45, and a one-way clutch 51. The transmission gear 45 is a specific example of a "first gear."

[0029] As shown in FIG. 4, the engaging member 32 has a generally cylindrical outer shape, and a coupling hole 33 is formed in the center of the engaging member 32. A recess 34 is formed in the inner peripheral portion of the lower surface of the engaging member 32, and a plurality of engaging portions 35 are formed on the bottom surface of the recess 34. The engaging portions 35 are, for example, teeth protruding downward from the bottom surface of the recess 34. As shown in FIG. 2, the engaging member 32 is attached to the lower end of the engine drive shaft 13 by inserting the lower end of the engine drive shaft 13 into the coupling hole 33. The engaging member 32 and the engine drive shaft 13 are spline-coupled to each other. The engaging member 32 is non-rotatable relative to the engine drive shaft 13, but rotates integrally with the engine drive shaft 13. The lower end of the engine drive shaft 13, to which the engaging member 32 is attached, is supported by the main body of the marine propulsion device 1 via a bearing 71 so as to be rotatable relative to the main body.

[0030] As shown in FIG. 4, the clutch shaft 36 is a shaft that extends in the vertical direction. An enlarged-diameter portion 38 having a larger diameter than an upper portion 37 of the clutch shaft 36 is formed at the lower portion of the clutch shaft 36. A coupling hole 39 is formed at the lower end of the clutch shaft 36. As shown in FIG. 2, the clutch shaft 36 is attached to the upper end of the upper transmission shaft 17 by inserting the upper end of the upper transmission shaft 17 into the coupling hole 39. The clutch shaft 36 and the upper transmission shaft 17 are spline-coupled to each other. The clutch shaft 36 is immovable relative to the upper transmission shaft 17, but rotates integrally with the upper transmission shaft 17. The upper end of the upper transmission shaft 17 to which the clutch shaft 36 is attached is supported by a bearing 72 on the main body of the marine propulsion device 1 so as to be rotatable relative to the main body.

[0031] As shown in FIG. 4 , the dog clutch 40 has a generally cylindrical outer shape and an insertion hole 41 formed in the center of the dog clutch 40. A plurality of upper engagement portions 42 are formed on the upper surface of the dog clutch 40. The upper engagement portions 42 are, for example, teeth protruding upward from the upper surface of the dog clutch 40. A plurality of lower engagement portions 43 are formed on the lower surface of the dog clutch 40. The lower engagement portions 43 are, for example, teeth protruding downward from the lower surface of the dog clutch 40. A fork mounting groove 44 is formed on the outer peripheral surface of the dog clutch 40. The fork mounting groove 44 extends around the entire circumference of the dog clutch 40. As shown in FIG. 2 , the dog clutch 40 is disposed below the engine drive shaft 13, specifically below the engaging member 32. The dog clutch 40 is attached to the upper portion 37 of the clutch shaft 36 by inserting the upper portion 37 of the clutch shaft 36 into the insertion hole 41. Furthermore, the dog clutch 40 is attached to an upper portion 37 of the clutch shaft 36 so as to be unable to rotate relative to the clutch shaft 36 but able to move up and down relative to the clutch shaft 36. For example, splines are formed on the inner circumferential surface of the insertion hole 41 of the dog clutch 40 and on the outer circumferential surface of the upper portion 37 of the clutch shaft 36, and these splines mesh with each other, so that the dog clutch 40 is unable to rotate relative to the clutch shaft 36 but able to move up and down relative to the clutch shaft 36.

[0032] As shown in FIG. 4, the transmission gear 45 is a bevel gear. The transmission gear 45 has a toothed portion 46 and a boss portion 50. The toothed portion 46 is formed in a truncated cone shape, and teeth are formed on the outer circumferential surface of the toothed portion 46. A recess 47 is formed on the inner circumferential portion of the upper surface of the toothed portion 46, and a plurality of engagement portions 48 are formed on the bottom surface of the recess 47. The engagement portions 48 are, for example, teeth that protrude upward from the bottom surface of the recess 47. An insertion hole 49 is formed in the center of the toothed portion 46. The boss portion 50 is formed in a cylindrical shape and extends downward from the toothed portion 46.

[0033] As shown in FIG. 2 , the transmission gear 45 is disposed on the outer circumferential side of the upper portion 37 of the clutch shaft 36 and below the dog clutch 40. The transmission gear 45 is rotatable relative to the clutch shaft 36. That is, the upper portion 37 of the clutch shaft 36 is inserted into an insertion hole 49 of the tooth portion 46 of the transmission gear 45. The diameter of the insertion hole 49 is larger than the outer diameter of the upper portion 37 of the clutch shaft 36, and the outer peripheral surface of the upper portion 37 of the clutch shaft 36 does not contact the inner peripheral surface of the insertion hole 49. The enlarged diameter portion 38 of the clutch shaft 36 is inserted into a boss portion 50 of the transmission gear 45. The inner diameter of the cylindrical boss portion 50 is larger than the outer diameter of the enlarged diameter portion 38 of the clutch shaft 36, and the outer peripheral surface of the enlarged diameter portion 38 of the clutch shaft 36 does not contact the inner peripheral surface of the boss portion 50. Furthermore, bearings 73 and 74 are provided between the boss portion 50 of the transmission gear 45 and the expanded diameter portion 38 of the clutch shaft 36, and the transmission gear 45 is supported on the clutch shaft 36 via the bearings 73 and 74 so as to be rotatable relative to the clutch shaft 36. Furthermore, a bearing 75 is provided between the boss portion 50 of the transmission gear 45 and the main body of the marine vessel propulsion device 1, and the transmission gear 45 is supported on the main body via the bearing 75 so as to be rotatable relative to the main body of the marine vessel propulsion device 1.

[0034] Additionally, the motor drive gear 15 attached to the front end of the motor drive shaft 14 is disposed behind the transmission gear 45, and the transmission gear 45 and the motor drive gear 15 mesh with each other. The front end of the motor drive shaft 14 to which the motor drive gear 15 is attached is supported by the main body of the marine propulsion unit 1 via a bearing 76 so as to be rotatable relative to the main body.

[0035] The one-way clutch 51 is formed in a cylindrical shape or a disk shape with a hole in the center when viewed overall. The one-way clutch 51 is disposed between the boss portion 50 of the transmission gear 45 and the expanded diameter portion 38 of the clutch shaft 36. Specifically, the one-way clutch 51 is disposed within the boss portion 50 of the transmission gear 45, and the expanded diameter portion 38 of the clutch shaft 36 is disposed on the inner peripheral side of the one-way clutch 51.

[0036] (Function and operation of power switching mechanism) The power switching mechanism 31 has a function of switching the power source that rotates the propellers 2, 3 between the engine 6, which is the first power source, and the motor 8, which is the second power source. The function of the power switching mechanism 31 is achieved by combining the function of the dog clutch 40 and the function of the one-way clutch 51.

[0037] First, we will explain the function and operation of the dog clutch 40. The dog clutch 40 switches the connection state of the engine drive shaft 13, the motor drive shaft 14, and the upper transmission shaft 17 between a state in which the engine drive shaft 13 and the upper transmission shaft 17 are connected to each other, and a state in which the motor drive shaft 14 and the upper transmission shaft 17 are connected to each other.

[0038] Specifically, as shown in FIG. 2 , when the dog clutch 40 moves upward, the engagement portion 35 of the engagement member 32 attached to the lower end of the engine drive shaft 13 and the upper engagement portion 42 of the dog clutch 40 engage with each other. As a result, the engine drive shaft 13 and the upper transmission shaft 17 are connected to each other via the engagement member 32, the dog clutch 40, and the clutch shaft 36. Furthermore, when the dog clutch 40 moves upward, the engagement portion 48 of the transmission gear 45 and the lower engagement portion 43 of the dog clutch 40 disengage from each other. As a result, the connection between the motor drive shaft 14 and the upper transmission shaft 17 via the motor drive gear 15, the transmission gear 45, the dog clutch 40, and the clutch shaft 36 is released. Therefore, when the dog clutch 40 moves upward, the rotation of the engine drive shaft 13 is transmitted to the upper transmission shaft 17 via the dog clutch 40, and at the same time, the rotation of the motor drive shaft 14 is no longer transmitted to the upper transmission shaft 17 via the dog clutch 40.

[0039] On the other hand, as shown in FIG. 3 , when the dog clutch 40 moves downward, the engagement portion 35 of the engagement member 32 and the upper engagement portion 42 of the dog clutch 40 are separated from each other. As a result, the connection between the engine drive shaft 13 and the upper transmission shaft 17 is released via the engagement member 32, the dog clutch 40, and the clutch shaft 36. Furthermore, when the dog clutch 40 moves downward, the engagement portion 48 of the transmission gear 45 and the lower engagement portion 43 of the dog clutch 40 are engaged with each other. As a result, the motor drive shaft 14 and the upper transmission shaft 17 are connected to each other via the motor drive gear 15, the transmission gear 45, the dog clutch 40, and the clutch shaft 36. Therefore, when the dog clutch 40 moves downward, the rotation of the engine drive shaft 13 is no longer transmitted to the upper transmission shaft 17 via the dog clutch 40, and at the same time, the rotation of the motor drive shaft 14 is transmitted to the upper transmission shaft 17 via the dog clutch 40.

[0040] Next, the function and operation of the one-way clutch 51 will be described. The one-way clutch 51 transmits the rotation of the transmission gear 45 to the upper transmission shaft 17 only when the rotation speed of the transmission gear 45 in a predetermined direction is higher than the rotation speed of the upper transmission shaft 17 in the predetermined direction. For example, while the upper transmission shaft 17 is rotating in the predetermined direction, the motor drive shaft 14 rotates, and the rotation of the motor drive shaft 14 is transmitted to the transmission gear 45, causing it to rotate in the predetermined direction. When the rotation speed of the transmission gear 45 is higher than the rotation speed of the upper transmission shaft 17, the rotation of the motor drive shaft 14 is transmitted to the upper transmission shaft 17 via the motor drive gear 15, the transmission gear 45, the one-way clutch 51, and the clutch shaft 36. On the other hand, while the upper transmission shaft 17 is rotating in the one predetermined direction, the motor drive shaft 14 rotates, and the rotation of the motor drive shaft 14 is transmitted to the transmission gear 45, causing the transmission gear 45 to rotate in the one predetermined direction. However, if the rotation speed of the transmission gear 45 is equal to or less than the rotation speed of the upper transmission shaft 17, the rotation of the motor drive shaft 14 is not transmitted to the upper transmission shaft 17 via the motor drive gear 15, the transmission gear 45, the one-way clutch 51, and the clutch shaft 36. The one predetermined direction is the direction in which the upper transmission shaft 17 rotates when the rotation of the crankshaft 7 of the engine 6 is transmitted to the upper transmission shaft 17.

[0041] Furthermore, in the power switching mechanism 31, the one-way clutch 51 operates only when the dog clutch 40 is moved upward and the transmission gear 45 is not connected to the upper transmission shaft 17 via the dog clutch 40 and the clutch shaft 36, as shown in FIG. 2. That is, as shown in FIG. 3, when the dog clutch 40 is moved downward and the transmission gear 45 is connected to the upper transmission shaft 17 via the dog clutch 40 and the clutch shaft 36, the one-way clutch 51 does not operate. That is, when the dog clutch 40 is moved downward, the transmission gear 45 and the upper transmission shaft 17 are coupled by the dog clutch 40 and rotate integrally, so that the transmission gear 45 does not rotate relative to the upper transmission shaft 17. Therefore, the one-way clutch 51 does not function.

[0042] The above-described functions of the dog clutch 40 and the one-way clutch 51 are combined to form the function of the power switching mechanism 31. That is, when the dog clutch 40 is moved up and the rotation speed of the transmission gear 45 in the predetermined direction is equal to or less than the rotation speed of the upper transmission shaft 17 in the predetermined direction, the power switching mechanism 31 transmits only the rotation of the engine drive shaft 13 to the upper transmission shaft 17. As a result, the engine 6 is the only power source that rotates the propellers 2, 3. Furthermore, when the dog clutch 40 is moved up and the rotation speed of the transmission gear 45 in the predetermined direction is higher than the rotation speed of the upper transmission shaft 17 in the predetermined direction, the power switching mechanism 31 transmits both the rotation of the engine drive shaft 13 and the rotation of the motor drive shaft 14 to the upper transmission shaft 17. As a result, the engine 6 and the motor 8 are the power sources that rotate the propellers 2, 3. Furthermore, when the dog clutch 40 moves downward, the power switching mechanism 31 transmits only the rotation of the motor drive shaft 14 to the upper transmission shaft 17. As a result, the motor 8 is the only power source that rotates the propellers 2 and 3.

[0043] (Example of ship operation mode and operation of power switching mechanism) Here, an example of the operating mode of the boat and the operation of the power switching mechanism 31 will be described. Before proceeding with this description, some background information will be provided. The rotation direction of the crankshaft 7 of the engine 6 is fixed due to the structure of the engine 6. When the rotation of the crankshaft 7 is transmitted to the upper transmission shaft 17, the rotation direction of the upper transmission shaft 17 becomes the predetermined one direction. Generally, the rotation direction of the output shaft 9 of the motor 8 can be easily reversed by controlling the motor 8, but in the boat propulsion device 1 of this embodiment, the motor 8 is controlled so that the rotation direction of the output shaft 9 of the motor 8 is always fixed. Then, when the rotation of the output shaft 9 is transmitted to the upper transmission shaft 17, the rotation direction of the output shaft 9 of the motor 8 is determined so that the rotation direction of the upper transmission shaft 17 becomes the predetermined one direction.

[0044] When the boat is operated at a low speed, the dog clutch 40 of the power switching mechanism 31 is moved downward, and the motor 8 is driven at a low rotation speed. As a result, only the rotation of the motor drive shaft 14 is transmitted to the upper transmission shaft 17 via the dog clutch 40. Therefore, the propellers 2 and 3 are rotated only by the power of the motor 8, and the boat moves only by the power of the motor 8. This allows the boat to move smoothly at an extremely low speed.

[0045] Furthermore, when the vessel is operated at a high, constant speed, the engine 6 is driven at a high constant rotational speed, the dog clutch 40 of the power switching mechanism 31 is moved up, and the motor 8 is stopped. As a result, the rotation of the engine drive shaft 13 is transmitted to the upper transmission shaft 17 via the dog clutch 40. Furthermore, because the rotational speed of the stopped motor 8 is zero, the rotation of the motor 8 is not transmitted to the upper transmission shaft 17 via the one-way clutch 51. Therefore, the propellers 2 and 3 rotate solely by the power of the engine 6, and the vessel moves solely by the power of the engine 6. This makes it possible to reduce electricity consumption when the vessel is moving at high speed.

[0046] Furthermore, when accelerating and planing the vessel, the dog clutch 40 of the power switching mechanism 31 is moved upward to increase the rotation speed of the driving engine 6, and at the same time, the motor 8 is driven to increase its rotation speed. As a result, the rotation of the engine drive shaft 13 is transmitted to the upper transmission shaft 17 via the dog clutch 40. Furthermore, when the rotation speed of the transmission gear 45 becomes greater than the rotation speed of the upper transmission shaft 17 due to the increase in the rotation speed of the motor 8, the rotation of the motor drive shaft 14 is transmitted to the upper transmission shaft 17 via the one-way clutch 51. Therefore, the propellers 2 and 3 are rotated by the power of both the engine 6 and the motor 8, and the vessel is accelerated by the power of both the engine 6 and the motor 8. This allows the vessel to accelerate quickly and smoothly.

[0047] (Dog clutch control) FIG. 5 shows a cross section of the power switching mechanism 31 taken along the direction of arrow VV in FIG. 2, as viewed from the front (left in FIG. 2).

[0048] 5, the marine vessel propulsion unit 1 is equipped with a control device 61 that controls the movement of the dog clutch 40. The control device 61 is disposed to the right of the dog clutch 40. In this embodiment, the power switching mechanism 31 including the dog clutch 40, the engine drive shaft 13, the motor 8, the motor drive shaft 14, the transmission shaft 16, the rotation direction switching mechanism 21, the rotation transmission mechanism 26, and the propeller shafts 4 and 5 are disposed in the center of the marine vessel propulsion unit 1 in the left-right direction, while the control device 61 is disposed on the right side of the marine vessel propulsion unit 1.

[0049] The control device 61 includes an actuator 62 (e.g., a small motor), two bevel gears 64 and 65, a cylindrical cam 66, and a fork 68. The actuator 62 is fixed to the main body of the marine vessel propulsion device 1. A bevel gear 64 is fixed to a rotating shaft 63 of the actuator 62, and the bevel gear 64 meshes with a bevel gear 65 fixed to the cylindrical cam 66. The cylindrical cam 66 is supported by the main body of the marine vessel propulsion device 1 via a bearing 77 or the like so as to be rotatable about an axis C extending in the vertical direction in FIG. 5. The base end portion of the fork 68 is attached to the outer periphery of the cylindrical cam 66. The tip end portion of the fork 68 is bifurcated and inserted into the fork mounting groove 44 of the dog clutch 40 so as to sandwich the dog clutch 40. A fork pin 69 is attached to the base end portion of the fork 68 , and the tip portion of the fork pin 69 is inserted into a cam groove 67 formed on the outer circumferential surface of the cylindrical cam 66 .

[0050] When the actuator 62 is driven and the rotating shaft 63 rotates, the rotation is transmitted to the cylindrical cam 66 via the bevel gears 64 and 65, causing the cylindrical cam 66 to rotate. As a result, the fork pin 69 inserted into the cam groove 67 is displaced upward or downward, causing the fork 68 to move upward or downward accordingly. The direction of movement of the fork 68 can be changed by controlling the drive of the actuator 62 to change the direction of rotation of the rotating shaft 63. When the fork 68 moves upward, the fork 68 pushes up the dog clutch 40, causing the dog clutch 40 to move upward. When the fork 68 moves downward, the fork 68 pushes down the dog clutch 40, causing the dog clutch 40 to move downward.

[0051] As described above, the marine vessel propulsion device 1 of the first embodiment of the present invention includes an engine 6 and a motor 8 as two power sources for rotating the propellers 2 and 3. The marine vessel propulsion device 1 of the present embodiment also includes a dog clutch 40 that switches the connection state of the engine drive shaft 13, the motor drive shaft 14, and the upper transmission shaft 17 between a state in which the engine drive shaft 13 and the upper transmission shaft 17 are connected to each other and a state in which the motor drive shaft 14 and the upper transmission shaft 17 are connected to each other. In the marine vessel propulsion device 1 of the present embodiment, switching of the power source for rotating the propellers 2 and 3 can be performed using the dog clutch 40. In a marine vessel propulsion device with two power sources, switching of the power source for rotating the propellers can also be performed using a centrifugal clutch. However, centrifugal clutches, for example, require a weight to engage and disengage the clutch using centrifugal force, and therefore increase in size as the torque capacity increases. In contrast, a dog clutch does not require such a weight. Therefore, compared to a centrifugal clutch, its structure makes it easier to prevent the size from increasing as the torque capacity increases. In the marine propulsion device 1 of this embodiment, the power source that rotates the propellers 2 and 3 is switched using a dog clutch 40, which makes it possible to simplify and compact the structure that transmits the power of the two power sources to the propellers 2 and 3, specifically the structure that switches between the power sources that rotate the propellers 2 and 3.

[0052] The marine propulsion device 1 of this embodiment is also equipped with a dog clutch 40 and a one-way clutch 51. In the marine propulsion device 1 of this embodiment, the cooperation of the dog clutch 40 and the one-way clutch 51 allows the power of two power sources, i.e., the power of the engine 6 and the power of the motor 8, to be combined and output to the propeller shafts 4, 5. In a marine propulsion device equipped with two power sources, the power of the two power sources can also be combined using a differential gear unit. However, a differential gear unit has a complex structure with many mechanical elements (gears, etc.), making it difficult to reduce the size of a differential gear unit. In contrast, a dog clutch and a one-way clutch can each be configured with fewer mechanical elements than a differential gear unit, making it easier to simplify and reduce the structure compared to a differential gear unit. Furthermore, even when a dog clutch and a one-way clutch are combined, it is easier to simplify and reduce the overall structure compared to a differential gear unit. The marine propulsion device 1 of this embodiment has a configuration in which the power of the two power sources is combined using the dog clutch 40 and the one-way clutch 51, which makes it possible to simplify and compact the structure that transmits the power of the two power sources to the propellers 2, 3, specifically the structure that combines the power of the two power sources and outputs it to the propeller shafts 4, 5.

[0053] Furthermore, in the marine propulsion device 1 of this embodiment, the engine drive shaft 13 and the upper transmission shaft 17 each extend in the vertical direction, the upper transmission shaft 17 is disposed below the engine drive shaft 13 and coaxially therewith, the dog clutch 40 is provided on an upper portion 37 of a clutch shaft 36 fixed to the upper transmission shaft 17 so as to be non-rotatable relative to the clutch shaft 36 but movable in the vertical direction relative to the clutch shaft 36, and when the dog clutch 40 moves upward, the engine drive shaft 13 and the dog clutch 40 engage with each other, thereby transmitting the rotation of the engine drive shaft 13 to the upper transmission shaft 17, and when the dog clutch 40 moves downward, the engine drive shaft 13 and the dog clutch 40 disengage from each other, thereby preventing the rotation of the engine drive shaft 13 from being transmitted to the upper transmission shaft 17. This configuration makes it possible to achieve the function of switching whether or not power from the engine 6 is transmitted to the propellers 2, 3 using a simple and compact structure.

[0054] Furthermore, in the marine propulsion device 1 of this embodiment, in addition to the above configuration, the motor drive shaft 14 extends in the fore-and-aft direction, the transmission gear 45 is arranged on the outer periphery of the clutch shaft 36 fixed to the upper transmission shaft 17 and below the dog clutch 40 so as to be rotatable relative to the clutch shaft 36, the motor drive gear 15 is arranged at the end of the motor drive shaft 14 so as not to be rotatable relative to the motor drive shaft 14, and transmits the rotation of the motor drive shaft 14 to the transmission gear 45, and when the dog clutch 40 moves downward, the transmission gear 45 and the dog clutch 40 engage with each other, thereby transmitting the rotation of the motor drive shaft 14 to the upper transmission shaft 17, and when the dog clutch 40 moves upward, the transmission gear 45 and the dog clutch 40 disengage from each other, so that the rotation of the motor drive shaft 14 is no longer transmitted to the upper transmission shaft 17. With this configuration, in addition to the function of switching whether or not to transmit the power of the engine 6 to the propellers 2 and 3, the function of switching whether or not to transmit the power of the motor 8 to the propellers 2 and 3 can be realized with a simple and compact structure.

[0055] Furthermore, in the marine vessel propulsion device 1 of this embodiment, an engagement portion 48 is provided on the inner peripheral portion of the upper part of the transmission gear 45, which engages with the dog clutch 40 when the dog clutch 40 moves downward. Thus, the transmission gear 45 has the engagement portion 48 which transmits the rotation of the transmission gear 45 to the dog clutch 40, in addition to the tooth portion 46 which transmits the rotation of the motor drive gear 15 to the transmission gear 45. By giving the transmission gear 45 these two functions, the number of mechanical elements which make up the power switching mechanism 31 can be reduced, allowing the power switching mechanism 31 to be made more compact, and ultimately the marine vessel propulsion device 1 to be made more compact.

[0056] Furthermore, in the marine vessel propulsion device 1 of this embodiment, the clutch shaft 36 extends in the vertical direction and is provided at the upper end of the upper transmission shaft 17 so as to be coaxial with the upper transmission shaft 17 and non-rotatable relative to the upper transmission shaft 17, the dog clutch 40 is provided on the clutch shaft 36 so as to be non-rotatable relative to the clutch shaft 36 but movable in the vertical direction relative to the clutch shaft 36, the transmission gear 45 is provided on the outer periphery of the clutch shaft 36 below the dog clutch 40 and so as to be rotatable relative to the clutch shaft 36, and the one-way clutch 51 is disposed between the boss portion 50 of the transmission gear 45 and the clutch shaft 36. With this configuration, the dog clutch 40 and the one-way clutch 51 can be disposed together, enabling the power switching mechanism 31 to be made more compact.

[0057] Furthermore, in the marine vessel propulsion unit 1 of this embodiment, the control device 61, which controls the movement of the dog clutch 40, is disposed to the right of the dog clutch 40. With this configuration, the length of the marine vessel propulsion unit 1 in the fore-and-aft direction can be shortened compared to when the control device 61 is disposed in front of the dog clutch 40. Furthermore, by not disposing the control device 61 in front of the dog clutch 40, the positions of the engine 6 and motor 8 within the marine vessel propulsion unit 1 can be moved closer to the front end of the marine vessel propulsion unit 1, and therefore the center of gravity of the marine vessel propulsion unit 1 can be disposed in the front part of the marine vessel propulsion unit 1. This makes it easier to tilt up the marine vessel propulsion unit 1. [Example]

[0058] Figures 6(A), 6(B), and 6(C) show a power switching mechanism 81 in a marine propulsion device according to a second embodiment of the present invention. In more detail, Figure 6(A) shows a state in which the dog clutch 85 is positioned midway in the vertical direction, Figure 6(B) shows a state in which the dog clutch 85 has moved up, and Figure 6(C) shows a state in which the dog clutch 85 has moved down.

[0059] Unlike the power switching mechanism 31 in the first embodiment of the present invention, the power switching mechanism 81 in the second embodiment of the present invention has a configuration in which a dog clutch 85 is used to switch the connection state of the engine drive shaft 13, the motor drive shaft 14, and the upper transmission shaft 17 between a first state in which the engine drive shaft 13 and the upper transmission shaft 17 are connected to each other, a second state in which the motor drive shaft 14 and the upper transmission shaft 17 are connected to each other, and a third state in which both the engine drive shaft 13 and the motor drive shaft 14 are connected to the upper transmission shaft 17. Also, unlike the power switching mechanism 31 in the first embodiment of the present invention, the power switching mechanism 81 in the second embodiment of the present invention does not have a one-way clutch 51. Except for these points, the marine vessel propulsion device in the second embodiment of the present invention is similar to the marine vessel propulsion device 1 in the first embodiment of the present invention.

[0060] In the power switching mechanism 81, as shown in FIG. 6(B), when the dog clutch 85 moves upward, the upper engagement portion 86 of the dog clutch 85 and the engagement portion 83 of the engagement member 82 engage with each other. As a result, the engine drive shaft 13 and the upper transmission shaft 17 are connected to each other via the engagement member 82, the dog clutch 85, and the dog clutch shaft 84. Furthermore, when the dog clutch 85 moves upward, the lower engagement portion 87 of the dog clutch 85 and the engagement portion 89 of the transmission gear 88 disengage from each other. As a result, the connection between the motor drive shaft 14 and the upper transmission shaft 17 via the motor drive gear 15, the transmission gear 88, the dog clutch 85, and the dog clutch shaft 84 is released. Therefore, when the dog clutch 85 moves upward, the rotation of the engine drive shaft 13 is transmitted to the upper transmission shaft 17 via the dog clutch 85, and at the same time, the rotation of the motor drive shaft 14 is no longer transmitted to the upper transmission shaft 17 via the dog clutch 85. Therefore, the propellers 2 and 3 are rotated only by the power of the engine 6.

[0061] 6(C), when the dog clutch 85 moves downward in the power switching mechanism 81, the upper engagement portion 86 of the dog clutch 85 and the engagement portion 83 of the engagement member 82 are separated from each other. As a result, the connection between the engine drive shaft 13 and the upper transmission shaft 17 is released via the engagement member 82, the dog clutch 85, and the dog clutch shaft 84. When the dog clutch 85 moves downward, the lower engagement portion 87 of the dog clutch 85 and the engagement portion 89 of the transmission gear 88 are engaged with each other. As a result, the motor drive shaft 14 and the upper transmission shaft 17 are connected to each other via the motor drive gear 15, the transmission gear 88, the dog clutch 85, and the dog clutch shaft 84. Therefore, when the dog clutch 85 moves downward, the rotation of the engine drive shaft 13 is no longer transmitted to the upper transmission shaft 17 via the dog clutch 85, and at the same time, the rotation of the motor drive shaft 14 is transmitted to the upper transmission shaft 17 via the dog clutch 85. Therefore, the propellers 2 and 3 are rotated only by the power of the motor 8.

[0062] 6A, when the dog clutch 85 of the power switching mechanism 81 moves to a vertically intermediate position, the upper engagement portion 86 of the dog clutch 85 and the engagement portion 83 of the engagement member 82 engage with each other. As a result, the engine drive shaft 13 and the upper transmission shaft 17 are connected to each other via the engagement member 82, the dog clutch 85, and the dog clutch shaft 84. When the dog clutch 85 moves to a vertically intermediate position, the lower engagement portion 87 of the dog clutch 85 and the engagement portion 89 of the transmission gear 88 engage with each other. As a result, the motor drive shaft 14 and the upper transmission shaft 17 are connected to each other via the motor drive gear 15, the transmission gear 88, the dog clutch 85, and the dog clutch shaft 84. Therefore, when the dog clutch 85 moves to a vertically intermediate position, both the rotation of the engine drive shaft 13 and the rotation of the motor 8 are transmitted to the upper transmission shaft 17 via the dog clutch 85. Therefore, the propellers 2 and 3 are rotated by the power of the engine 6 and the power of the motor 8 .

[0063] As described above, the marine vessel propulsion device of the second embodiment of the present invention has a configuration in which switching between the power sources that rotate the propellers 2, 3 and combining the power of the two power sources is performed by the dog clutch 85. Therefore, according to the marine vessel propulsion device of the second embodiment of the present invention, it is possible to simplify and compact the structure that transmits the power of the two power sources to the propellers 2, 3.

[0064] In the second embodiment, the dog clutch 85 is used to switch the connection state of the engine drive shaft 13, the motor drive shaft 14, and the upper transmission shaft 17 between the first state, the second state, and the third state, but the present invention is not limited to this. The dog clutch 85 may be used to switch the connection state of the engine drive shaft 13, the motor drive shaft 14, and the upper transmission shaft 17 only between the first state and the second state, only between the first state and the third state, or only between the second state and the third state.

[0065] In addition, in each of the above embodiments, the first power source is the engine 6 and the second power source is the motor 8, but the present invention is not limited to this. The first power source may be a motor and the second power source may be an engine, or the first power source may be a motor and the second power source may be another motor.

[0066] In each of the above embodiments, the second power source (motor 8) is disposed below and rearward of the first power source (engine 6) so that the extension direction of the output shaft 9 is in the front-rear direction. The second drive shaft (motor drive shaft 14) connected to the second power source extends in the front-rear direction. However, the present invention is not limited to this. The second power source (motor 8) may be disposed below and to the left or right of the first power source (engine 6) so that the extension direction of the output shaft 9 is in the left-right direction, and the extension direction of the second drive shaft may be in the left-right direction. The second power source (motor 8) may be disposed below and forward of the first power source (engine 6) so that the extension direction of the output shaft 9 is in the front-rear direction, and the extension direction of the second drive shaft may be in the front-rear direction.

[0067] In addition, in each of the above embodiments, an example has been given in which the clutch shaft 36 is provided at the upper end of the upper transmission shaft 17 and the dog clutch 40 is attached to the clutch shaft 36, but the present invention is not limited to this. A configuration in which the dog clutch 40 is directly attached to the upper end of the upper transmission shaft 17 without providing the clutch shaft 36 may also be used.

[0068] In addition, in each of the above embodiments, the control device 61 that controls the movement of the dog clutch 40 (85) is disposed to the right of the dog clutch 40 (85), but the present invention is not limited to this. For example, the control device 61 may be disposed to the left of the dog clutch 40 (85).

[0069] Although the marine propulsion devices in the above embodiments employ contra-rotating propellers, the present invention can also be applied to marine propulsion devices that do not employ contra-rotating propellers. Furthermore, although the marine propulsion devices in the above embodiments are outboard motors, the present invention can also be applied to other types of marine propulsion devices other than outboard motors.

[0070] Furthermore, the present invention can be modified as appropriate within the scope of the claims and the spirit or concept of the invention that can be read from the entire specification, and a marine propulsion device with such modifications is also included in the technical concept of the present invention. [Explanation of symbols]

[0071] 1 Ship propulsion machine 2, 3 propellers 4, 5 Propeller shaft 6 Engine (primary power source) 8 Motor (second power source) 13 Engine drive shaft (first drive shaft) 14 Motor drive shaft (second drive shaft) 15 Motor drive gear (second gear) 16 Transmission shaft 31, 81 Power switching mechanism 36, 84 clutch shaft 40, 85 Dog clutch 45, 88 Transmission gear (first gear) 48, 89 Engagement part 50 Boss Section (Boss) 51 One-way clutch 61 Control device

Claims

1. Propeller and a first power source that rotates the propeller; a second power source that rotates the propeller; and a propeller shaft provided with the propeller; a first drive shaft connected to the first power source; a second drive shaft connected to the second power source; a transmission shaft connected to the propeller shaft; a dog clutch that switches the connection modes of the first drive shaft, the second drive shaft, and the transmission shaft between at least two of a first mode in which the first drive shaft and the transmission shaft are connected to each other, a second mode in which the second drive shaft and the transmission shaft are connected to each other, and a third mode in which both the first drive shaft and the second drive shaft are connected to the transmission shaft.

2. the first drive shaft and the transmission shaft each extend in a vertical direction, and the transmission shaft is disposed below the first drive shaft and coaxially with the first drive shaft; the dog clutch is provided at an upper end of the transmission shaft so as to be unable to rotate relative to the transmission shaft but to be movable up and down relative to the transmission shaft, 2. The marine propulsion device according to claim 1, wherein when the dog clutch moves upward, the first drive shaft and the dog clutch engage with each other, thereby transmitting rotation of the first drive shaft to the transmission shaft, and when the dog clutch moves downward, the first drive shaft and the dog clutch disengage from each other, thereby preventing rotation of the first drive shaft from being transmitted to the transmission shaft.

3. a first gear and a second gear; the second drive shaft extends in a direction perpendicular to the up-down direction, the first gear is provided on the outer circumferential side of the transmission shaft and below the dog clutch so as to be rotatable relative to the transmission shaft, the second gear is provided at an end of the second drive shaft so as to be non-rotatable relative to the second drive shaft, and transmits rotation of the second drive shaft to the first gear; 3. The marine propulsion device according to claim 2, wherein when the dog clutch moves downward, the first gear and the dog clutch are engaged with each other, thereby transmitting the rotation of the second drive shaft to the transmission shaft, and when the dog clutch moves upward, the first gear and the dog clutch are disengaged from each other, thereby preventing the rotation of the second drive shaft from being transmitted to the transmission shaft.

4. Equipped with a one-way clutch, the one-way clutch is provided between the first gear and the transmission shaft, the dog clutch switches a connection state of the first drive shaft, the second drive shaft, and the transmission shaft between the first state and the second state; 4. A marine propulsion device according to claim 3, wherein when the dog clutch moves upward to disengage the first gear and the dog clutch from each other, and when the rotation speed of the first gear in a predetermined direction is higher than the rotation speed of the transmission shaft in the predetermined direction, the rotation of the second drive shaft is transmitted to the transmission shaft by the one-way clutch.

5. 4. A marine propulsion device according to claim 3, wherein an engaging portion is provided on an inner peripheral portion of an upper portion of the first gear, which engages with the dog clutch when the dog clutch moves downward.

6. Equipped with a clutch shaft, the clutch shaft extends in the vertical direction and is provided at an upper end of the transmission shaft so as to be coaxial with the transmission shaft and non-rotatable relative to the transmission shaft; the dog clutch is provided on the clutch shaft so as to be unable to rotate relative to the clutch shaft and to be movable up and down relative to the clutch shaft, the first gear is provided on the outer circumferential side of the clutch shaft and below the dog clutch so as to be rotatable relative to the clutch shaft, 5. A marine propulsion device according to claim 4, wherein the one-way clutch is disposed between a boss of the first gear and the clutch shaft.

7. a control device for controlling movement of the dog clutch; the second drive shaft extends in the front-rear direction; 4. A marine propulsion device according to claim 3, wherein the control device is disposed to the left or right of the dog clutch.

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