Marine propulsion device

Abstract

To properly cool a plurality of power sources for each power source, in a ship propulsion machine having the plurality of power sources for rotating a propeller.SOLUTION: The vessel propulsion apparatus 1 includes an engine and a motor as power sources that rotate a propeller. Further, the cooling structure 31 of the ship propulsion machine includes a first cooling water supply passage 33 which connects the water intake port 32 and the engine cooling mechanism 35, a water pump 34 which sends cooling water in the first cooling water supply passage 33 toward the engine cooling mechanism 35, a first cooling water discharge passage 36 which connects the engine cooling mechanism 35 and the water discharge port 37, a heat exchanger 43, a cooling medium circulation passage 39 which circulates a cooling medium between the motor cooling mechanism 41 and the heat exchanger 43, a second cooling water supply passage 45 which branches from the first cooling water supply passage 33 and connects the first cooling water supply passage 33 and the heat exchanger 43, and a second cooling water discharge passage 46 which connects the heat exchanger 43 and the water discharge port 37.SELECTED DRAWING: FIG. 4.

Description

[Technical Field]

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

[0002] One type of marine propulsion device equipped with multiple power sources to rotate the propellers is a hybrid marine propulsion device that has an engine and a motor and uses the power of the engine and the power of the motor to rotate the propellers. Japanese Patent Laid-Open Publication No. 2007-8329 (Patent Document 1) describes a hybrid outboard motor. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-8329 Summary of the Invention [Problem to be solved by the invention]

[0004] Whether the power source is an engine or a motor, cooling the power source is important in order to improve the durability or performance of the power source. In addition, in order to increase the cooling efficiency of the power source, it is preferable to adopt a liquid-cooling method rather than an air-cooling method.

[0005] In the liquid cooling method, a cooling passage is provided inside or around the power source, and a cooling liquid is supplied to the power source and the cooling liquid is caused to flow through the cooling passage of the power source, thereby cooling the power source.

[0006] Furthermore, when focusing on the method of supplying coolant to a power source provided with a cooling passage, liquid-cooling cooling methods are classified into direct cooling and indirect cooling. Direct cooling is a method in which water outside the marine propulsion engine (e.g., seawater) is directly supplied to the power source to cool it. Indirect cooling is a method in which a circulation path for circulating coolant is formed inside the marine propulsion engine, the power source and a heat exchanger are connected to the circulation path, water outside the marine propulsion engine is supplied to the heat exchanger, the coolant circulating through the circulation path is cooled by the heat exchanger, and the coolant is used to cool the power source.

[0007] In a marine propulsion unit equipped with multiple power sources, it is desirable to cool each power source by a liquid-cooling method. When cooling each power source by a liquid-cooling method, a cooling passage is provided inside or around each power source, and a supply passage is provided inside or around the marine propulsion unit to supply coolant to each power source.

[0008] In a marine propulsion device equipped with multiple power sources, when the multiple power sources are switched between depending on the operating mode of the marine vessel, the heat generation amount of each of the multiple power sources varies depending on the operating mode of the marine vessel. Therefore, it is necessary to appropriately cool each of the multiple power sources. Therefore, it is necessary to construct a supply passage that supplies coolant to each of the multiple power sources so that it is easy to appropriately cool each of the multiple power sources.

[0009] In this regard, in a marine propulsion device equipped with multiple power sources, if the supply passage is configured so that a coolant is supplied to a first power source and the coolant that has flowed through the cooling passage of the first power source is supplied to a second power source, the coolant that has been heated by flowing through the cooling passage of the first power source will be supplied to the second power source, which could result in, for example, excessive cooling of the first power source and insufficient cooling of the second power source, making it difficult to appropriately cool the first power source and the second power source separately.Furthermore, if the supply passage is configured so that a coolant is supplied to a first power source and the coolant that has flowed through the cooling passage of the first power source is supplied to the second power source, it becomes difficult to individually change the amount of coolant supplied to the first power source and the amount of coolant supplied to the second power source, making it difficult to appropriately cool the first power source and the second power source separately.

[0010] Furthermore, although the above-mentioned Japanese Patent Application Laid-Open No. 2007-8329 describes cooling of the engine, it does not describe cooling of the motor.

[0011] 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 multiple power sources that rotate propellers, which can appropriately cool each of the multiple power sources individually. [Means for solving the problem]

[0012] In order to solve the above problem, a first marine propulsion device of the present invention is a marine propulsion device for propelling a marine vessel, comprising: a first power source that rotates a propeller; a second power source that rotates the propeller; a water intake; a first cooling water supply passage that connects the water intake and the first power source; a pump that sends water that flows into the first cooling water supply passage from outside the marine propulsion device through the water intake toward the first power source as cooling water; a drain outlet; a first cooling water discharge passage that connects the first power source and the drain outlet; a heat exchanger; a cooling medium circulation passage that circulates a cooling medium between the second power source and the heat exchanger; a second cooling water supply passage that branches off from the first cooling water supply passage and connects the first cooling water supply passage and the heat exchanger; and a second cooling water discharge passage that connects the heat exchanger and the drain outlet.

[0013] In addition, in order to solve the above-mentioned problem, a second marine propulsion device of the present invention is a marine propulsion device for propelling a marine vessel, comprising: a first power source that rotates a propeller; a second power source that rotates the propeller; a water intake; a first cooling water supply passage that connects the water intake and the first power source; a pump that sends water that flows into the first cooling water supply passage from outside the marine propulsion device through the water intake toward the first power source as cooling water; a drain outlet; a first cooling water discharge passage that connects the first power source and the drain outlet; a second cooling water supply passage that branches off from the first cooling water supply passage and connects the first cooling water supply passage and the second power source; and a second cooling water discharge passage that connects the second power source and the drain outlet. [Effects of the Invention]

[0014] According to the present invention, in a marine propulsion device equipped with a plurality of power sources that rotate propellers, each of the plurality of power sources can be appropriately cooled. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is an explanatory diagram showing a marine propulsion device according to a first embodiment of the present invention. [Figure 2] 1 is an explanatory diagram showing a power transmission mechanism in a marine propulsion device according to a first embodiment of the present invention. [Figure 3] 1 is an explanatory diagram showing a power switching mechanism in a power transmission mechanism of a marine propulsion device according to a first embodiment of the present invention. FIG. [Figure 4] 1 is an explanatory diagram showing a cooling structure in a marine propulsion device according to a first embodiment of the present invention. [Figure 5] FIG. 6 is an explanatory diagram showing a cooling structure in a marine propulsion device according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0016] (First embodiment) A boat propulsion device according to a first embodiment of the present invention is a boat propulsion device that propels a boat, and includes a first power source that rotates a propeller, and a second power source that rotates a propeller.

[0017] In addition, the marine propulsion device of the first embodiment includes a water intake, a first cooling water supply passage connecting the water intake and the first power source, a pump that sends water that flows into the first cooling water supply passage from outside the marine propulsion device through the water intake toward the first power source as cooling water, a drain outlet, and a first cooling water discharge passage connecting the first power source and the drain outlet.

[0018] Furthermore, the marine propulsion device of the first embodiment includes a heat exchanger, a cooling medium circulation passage that circulates a cooling medium between the second power source and the heat exchanger, a second cooling water supply passage that branches off from the first cooling water supply passage and connects the first cooling water supply passage and the heat exchanger, and a second cooling water discharge passage that connects the heat exchanger and a drain outlet.

[0019] In the marine propulsion device of the first embodiment having this configuration, water that flows into the first cooling water supply passage from outside the marine propulsion device through the water intake port due to the drive of the pump flows as cooling water through the first cooling water supply passage toward the first power source. For example, a cooling passage is formed inside or around the first power source. The cooling water that flows through the first cooling water supply passage then flows through the cooling passage of the first power source. This cools the first power source. The cooling water that flows through the cooling passage of the first power source then flows through the first cooling water discharge passage toward the discharge port and is then discharged from the discharge port to the outside of the marine propulsion device.

[0020] Furthermore, when the pump is driven, a portion of the cooling water flowing through the first cooling water supply passage flows into a second cooling water supply passage branching off from the first cooling water supply passage, and flows through the second cooling water supply passage toward the heat exchanger. The cooling water that has flowed through the second cooling water supply passage then flows through the heat exchanger. As a result, the cooling medium circulating between the second power source and the heat exchanger is cooled by the heat exchanger. The cooling water that has flowed through the heat exchanger then flows through the second cooling water discharge passage toward the discharge port, and is then discharged from the discharge port to outside the marine propulsion device.

[0021] The second power source and the heat exchanger are each connected to a cooling medium circulation passage. The cooling medium cooled by the heat exchanger circulates between the heat exchanger and the second power source by flowing through the cooling medium circulation passage. For example, a cooling passage is formed inside or around the second power source. As the cooling medium circulates between the second power source and the heat exchanger, it flows through the cooling passage of the second power source. This cools the second power source. The flow of the cooling medium in the cooling medium circulation passage can be created, for example, by connecting another pump to the cooling medium circulation passage and driving the other pump.

[0022] In the marine propulsion device of the first embodiment, the cooling water after flowing through the cooling passage for the first power source flows through the first cooling water discharge passage and is then discharged from the discharge port to the outside of the marine propulsion device. Therefore, the cooling water after flowing through the cooling passage for the first power source does not flow through the heat exchanger, and therefore the cooling water whose temperature has increased by flowing through the cooling passage for the first power source does not flow through the heat exchanger. Furthermore, the cooling water after flowing through the heat exchanger flows through the second cooling water discharge passage and is then discharged from the discharge port to the outside of the marine propulsion device. Therefore, the cooling water after flowing through the heat exchanger does not flow through the cooling passage for the first power source, and therefore the cooling water whose temperature has increased by flowing through the heat exchanger does not flow through the cooling passage for the first power source. Therefore, according to the marine propulsion device of this embodiment, it is easy to cool the first power source and the heat exchanger individually, and therefore the first power source and the second power source can be appropriately cooled separately. Specifically, for example, it is possible to prevent the first power source from being excessively cooled while the second power source is being insufficiently cooled, and it is possible to cool each power source just right.

[0023] Furthermore, in the marine propulsion device of the first embodiment, it is technically easy to provide a valve at the branch point between the first and second cooling water supply passages to control the flow of cooling water from the first cooling water supply passage to the second cooling water supply passage. By providing such a valve, the ratio between the amount of cooling water supplied to the first power source and the amount of cooling water supplied to the heat exchanger can be changed. Thus, the marine propulsion device of the first embodiment of the present invention makes it easy to individually set the amount of cooling water supplied to the first power source and the amount of cooling water supplied to the heat exchanger, thereby enabling the first power source and the second power source to be appropriately cooled separately. For example, when the first power source is operating and the second power source is stopped, the ratio of the amount of cooling water supplied to the first power source relative to the amount of cooling water supplied to the heat exchanger can be increased, thereby prioritizing cooling of the first power source over cooling of the second power source.

[0024] (Second embodiment) A boat propulsion device according to a second embodiment of the present invention is a boat propulsion device that propels a boat, and includes a first power source that rotates a propeller, and a second power source that rotates a propeller.

[0025] In addition, the marine propulsion device of the second embodiment includes a water intake, a first cooling water supply passage connecting the water intake and the first power source, a pump that sends water that flows into the first cooling water supply passage from outside the marine propulsion device through the water intake toward the first power source as cooling water, a drain outlet, and a first cooling water discharge passage connecting the first power source and the drain outlet.

[0026] Furthermore, the marine propulsion device of the second embodiment includes a second cooling water supply passage branching from the first cooling water supply passage and connecting the first cooling water supply passage and the second power source, and a second cooling water discharge passage connecting the second power source and the drain outlet.

[0027] In the marine propulsion device of the second embodiment having this configuration, water that flows into the first cooling water supply passage from outside the marine propulsion device through the water intake port due to the drive of the pump flows as cooling water through the first cooling water supply passage toward the first power source. The cooling water that flows through the first cooling water supply passage then flows through the cooling passage for the first power source. This cools the first power source. The cooling water that flows through the cooling passage for the first power source then flows through the first cooling water discharge passage toward the discharge port and is then discharged from the discharge port to the outside of the marine propulsion device.

[0028] Furthermore, when the pump is driven, a portion of the cooling water flowing through the first cooling water supply passage flows into a second cooling water supply passage branching off from the first cooling water supply passage, and flows through the second cooling water supply passage toward the second power source. The cooling water that has flowed through the second cooling water supply passage then flows through the cooling passage for the second power source, thereby cooling the second power source. The cooling water that has flowed through the cooling passage for the second power source then flows through the second cooling water discharge passage toward the discharge port, and is then discharged from the discharge port to outside the marine propulsion device.

[0029] In the marine propulsion device of the second embodiment, the cooling water after flowing through the cooling passage for the first power source flows through the first cooling water discharge passage and is then discharged from the discharge port to the outside of the marine propulsion device. Therefore, the cooling water after flowing through the cooling passage for the first power source does not flow through the cooling passage for the second power source, and therefore the cooling water whose temperature has increased by flowing through the cooling passage for the first power source does not flow through the cooling passage for the second power source. Furthermore, the cooling water after flowing through the cooling passage for the second power source flows through the second cooling water discharge passage and is then discharged from the discharge port to the outside of the marine propulsion device. Therefore, the cooling water after flowing through the cooling passage for the second power source does not flow through the cooling passage for the first power source, and therefore the cooling water whose temperature has increased by flowing through the cooling passage for the second power source does not flow through the cooling passage for the first power source. Therefore, according to the marine propulsion device of this embodiment, it is easy to cool the first power source and the second power source individually, and therefore the first power source and the second power source can be appropriately cooled separately.

[0030] Furthermore, in the marine vessel propulsion device of the first embodiment, it is technically easy to provide a valve, for example, at the branch point between the first and second cooling water supply passages, to control the flow of cooling water from the first cooling water supply passage to the second cooling water supply passage. By providing such a valve, it is possible to change the ratio between the amount of cooling water supplied to the first power source and the amount of cooling water supplied to the second power source. In this way, the marine vessel propulsion device of the first embodiment of the present invention makes it easy to individually set the amount of cooling water supplied to the first power source and the amount of cooling water supplied to the second power source, thereby making it possible to appropriately cool the first power source and the second power source separately. [Example]

[0031] (ship propulsion equipment) FIG. 1 shows a boat propulsion device 1 according to a first embodiment of the present invention. The boat propulsion device 1 is a device for propelling a boat. The boat propulsion device 1 of this embodiment is an outboard motor that is attached to a boat. As shown in FIG. 1, the boat propulsion device 1 includes a propeller 2, an engine (internal combustion engine) 4 that is a first power source for rotating the propeller 2, a motor (electric motor) 6 that is a second power source for rotating the propeller 2, and an inverter 8 that controls the drive of the motor 6.

[0032] (Power transmission mechanism) FIG. 2 shows the power transmission mechanism 11 of the marine propulsion unit 1. As shown in FIG. 2, the marine propulsion unit 1 includes the power transmission mechanism 11 that transmits the power of the engine 4 and the motor 6 to the propeller 2. The power transmission mechanism 11 includes an engine drive shaft 12, a motor drive shaft 13, a transmission shaft 15, a power switching mechanism 16, and a rotation transmission mechanism 23. The engine drive shaft 12 is connected to the crankshaft 5 of the engine 4 via a gear and rotates in response to the rotation of the crankshaft 5. The motor drive shaft 13 is connected to the output shaft 7 of the motor 6 and rotates integrally with the output shaft 7. The power switching mechanism 16 switches between transmitting the rotation of the engine drive shaft 12 to the transmission shaft 15 and transmitting the power of the motor drive shaft 13 to the transmission shaft 15. The transmission shaft 15 is connected to the output side of the power switching mechanism 16 and transmits the rotation of the engine drive shaft 12 or the motor drive shaft 13 to the rotation transmission mechanism 23. The rotation transmission mechanism 23 is a mechanism that transmits the rotation of the transmission shaft 15 to the propeller shaft 3. The rotation transmission mechanism 23 has a first gear mechanism 24 that switches the rotation direction of the propeller shaft 3. The marine vessel propulsion device 1 of this embodiment also employs contra-rotating propellers, and is equipped with two propellers 2 and two propeller shafts 3 to which the propellers 2 are respectively fixed. The rotation transmission mechanism 23 has a second gear mechanism 25 that transmits the rotation of the transmission shaft 15 to the two propeller shafts 3 so that the rotation directions of the propeller shafts 3 are opposite to each other.

[0033] (Power switching mechanism) Figure 3 shows a detailed configuration of the power switching mechanism 16. In particular, Figure 3(A) shows the power switching mechanism 16 in a state where the dog clutch 19 has moved up, and Figure 3(B) shows the power switching mechanism 16 in a state where the dog clutch 19 has moved down.

[0034] As shown in FIG. 3(A), the power switching mechanism 16 includes an engagement member 17, a clutch shaft 18, a dog clutch 19, a transmission gear 20, and a one-way clutch 21. The engine drive shaft 12 and the transmission shaft 15 each extend vertically, with the lower end of the engine drive shaft 12 and the upper end of the transmission shaft 15 facing each other. The motor drive shaft 13 extends longitudinally, with the front end of the motor drive shaft 13 facing the space between the lower end of the engine drive shaft 12 and the upper end of the transmission shaft 15. The engagement member 17 is fixed to the lower end of the engine drive shaft 12 and rotates integrally with the engine drive shaft 12. The clutch shaft 18 is fixed to the upper end of the transmission shaft 15 and rotates integrally with the transmission shaft 15. The dog clutch 19 is disposed below the engagement member 17. The dog clutch 19 is attached to the upper part of the clutch shaft 18 so as to be unable to rotate relative to the clutch shaft 18 but to be movable vertically relative to the clutch shaft 18. The transmission gear 20 is disposed on the outer peripheral side of the upper part of the clutch shaft 18, below the dog clutch 19. The transmission gear 20 is provided so as to be rotatable relative to the clutch shaft 18. That is, an insertion hole 20A is formed in the center of the transmission gear 20, and the upper part of the clutch shaft 18 is inserted into the insertion hole 20A. The diameter of the insertion hole 20A is larger than the outer diameter of the upper part of the clutch shaft 18, and the outer peripheral surface of the upper part of the clutch shaft 18 does not contact the inner peripheral surface of the insertion hole 20A. The transmission gear 20 is a bevel gear, and is engaged with the motor drive gear 14. The motor drive gear 14 is fixed to the front end of the motor drive shaft 13 and rotates integrally with the motor drive shaft 13. A one-way clutch 21 is attached between the lower part of the clutch shaft 18 and the boss of the transmission gear 20.

[0035] The dog clutch 19 has the function of switching the connection state of the engine drive shaft 12, the motor drive shaft 13, and the transmission shaft 15 between a state in which the engine drive shaft 12 and the transmission shaft 15 are connected to each other and a state in which the motor drive shaft 13 and the transmission shaft 15 are connected to each other. The one-way clutch 21 has the function of transmitting the rotation of the transmission gear 20 to the transmission shaft 15 only when the rotation speed of the transmission gear 20 in a predetermined direction is higher than the rotation speed of the transmission shaft 15 in the predetermined direction. The function of the power switching mechanism 16 is created by combining the function of the dog clutch 19 and the function of the one-way clutch 21. Specifically, the function and operation of the power switching mechanism 16 are as follows.

[0036] As shown in FIG. 3A, when the dog clutch 19 moves upward, an engagement portion 19A formed on the upper part of the dog clutch 19 and an engagement portion 17A formed on the engagement member 17 engage with each other. As a result, the engine drive shaft 12 and the transmission shaft 15 are connected to each other via the engagement member 17, the dog clutch 19, and the clutch shaft 18. This allows the rotation of the engine drive shaft 12 to be transmitted to the transmission shaft 15 via the dog clutch 19. Furthermore, when the dog clutch 19 moves upward, an engagement portion 19B formed on the lower part of the dog clutch 19 and an engagement portion 20B formed on the transmission gear 20 separate from each other. As a result, the connection between the motor drive shaft 13 and the transmission shaft 15 via the motor drive gear 14, the transmission gear 20, the dog clutch 19, and the clutch shaft 18 is released. This prevents the rotation of the motor drive shaft 13 from being transmitted to the transmission shaft 15 via the dog clutch 19.

[0037] Furthermore, when the dog clutch 19 moves upward, the rotation of the motor drive shaft 13 is transmitted to the transmission shaft 15 via the one-way clutch 21 only when the rotation speed of the transmission gear 20 in the one predetermined direction is higher than the rotation speed of the transmission shaft 15 in the one predetermined direction. That is, the rotation of the motor 6 is transmitted to the transmission gear 20 via the motor drive shaft 13 and the motor drive gear 14. The motor 6 is controlled so that the rotation direction of the transmission gear 20 becomes the one predetermined direction when the rotation of the motor 6 is transmitted to the transmission gear 20. The one predetermined direction is the rotation direction of the transmission shaft 15 when the rotation of the engine 4 is transmitted to the transmission shaft 15 via the engine drive shaft 12, the dog clutch 19, etc. As the rotation speed of the motor 6 increases, the rotation speed of the transmission gear 20 in the one predetermined direction increases accordingly. When the rotation speed of the transmission gear 20 in the predetermined direction becomes higher than the rotation speed of the transmission shaft 15 in the predetermined direction, the rotation of the transmission shaft 15 is transmitted to the transmission shaft 15 via the one-way clutch 21.

[0038] In this way, when the dog clutch 19 moves up and the rotation speed of the transmission gear 20 in the one predetermined direction is higher than the rotation speed of the transmission shaft 15 in the one predetermined direction, the rotation of the engine drive shaft 12 is transmitted to the transmission shaft 15 via the dog clutch 19, and at the same time, the rotation of the motor drive shaft 13 is transmitted to the transmission shaft 15 via the one-way clutch 21. On the other hand, when the dog clutch 19 moves up and the rotation speed of the transmission gear 20 in the one predetermined direction is equal to or lower than the rotation speed of the transmission shaft 15 in the one predetermined direction, only the rotation of the engine drive shaft 12 is transmitted to the transmission shaft 15 via the dog clutch 19.

[0039] On the other hand, as shown in FIG. 3(B), when the dog clutch 19 moves downward, an engagement portion 19A formed on the upper part of the dog clutch 19 and an engagement portion 17A formed on the engagement member 17 are separated from each other. As a result, the connection between the engine drive shaft 12 and the transmission shaft 15 via the engagement member 17, the dog clutch 19, and the clutch shaft 18 is released. As a result, the rotation of the engine drive shaft 12 is no longer transmitted to the transmission shaft 15 via the dog clutch 19. Furthermore, when the dog clutch 19 moves downward, an engagement portion 19B formed on the lower part of the dog clutch 19 and an engagement portion 20B formed on the transmission gear 20 are engaged with each other. As a result, the motor drive shaft 13 and the transmission shaft 15 are connected to each other via the motor drive gear 14, the transmission gear 20, the dog clutch 19, and the clutch shaft 18. As a result, the rotation of the motor drive shaft 13 is transmitted to the transmission shaft 15 via the dog clutch 19. Furthermore, when the dog clutch 19 moves downward, the transmission gear 20 and the clutch shaft 18 rotate together via the dog clutch 19, and the one-way clutch 21 attached between the transmission gear 20 and the clutch shaft 18 does not operate. In this way, when the dog clutch 19 moves downward, the rotation of the motor drive shaft 13 is only transmitted to the transmission shaft 15 via the dog clutch 19.

[0040] For example, when the vessel is operated at a low speed, the dog clutch 19 is moved downward so that the rotation of the motor drive shaft 13 is transmitted only to the transmission shaft 15 via the dog clutch 19. Then, the motor 6 is driven and the engine 4 is put into an idling state. As a result, only the power of the motor 6 is transmitted to the propeller shaft 3, and the propeller 2 rotates only by the power of the motor 6. This allows the vessel to move smoothly at an extremely low speed.

[0041] Furthermore, when the vessel is operated at a high, constant speed, the dog clutch 19 is moved up so that the rotation of the engine drive shaft 12 is transmitted to the transmission shaft 15 via the dog clutch 19, and the rotation of the motor drive shaft 13 is transmitted to the transmission shaft 15 via the one-way clutch 21. Then, the engine 4 is driven at a constant high speed, and the motor 6 is stopped. As a result, only the power of the engine 4 is transmitted to the propeller shaft 3, and the propeller 2 rotates only by the power of the engine 4. This reduces electricity consumption.

[0042] When accelerating the vessel to planing, the dog clutch 19 is moved upward, so that the rotation of the engine drive shaft 12 is transmitted to the transmission shaft 15 via the dog clutch 19, and the rotation of the motor drive shaft 13 is transmitted to the transmission shaft 15 via the one-way clutch 21. Then, the engine 4 and the motor 6 are driven, increasing their respective rotation speeds. As a result, the power of the engine 4 is transmitted to the propeller shaft 3 via the dog clutch 19. Furthermore, when the rotation speed of the motor 6 increases, the rotation speed of the transmission gear 20 in the predetermined one direction becomes higher than the rotation speed of the transmission shaft 15 in the predetermined one direction, so that the power of the motor 6 is transmitted to the propeller shaft 3 via the one-way clutch 21. Therefore, the propeller 2 rotates by both the power of the engine 4 and the power of the motor 6. This allows the vessel to accelerate quickly and smoothly.

[0043] (cooling structure) Fig. 4 shows the cooling structure 31 of the marine propulsion unit 1. As shown in Fig. 4, the marine propulsion unit 1 has a liquid-cooled cooling structure 31 that cools the engine 4, motor 6, and inverter 8. The cooling structure 31 includes a water intake 32, a first cooling water supply passage 33, a water pump 34, an engine cooling mechanism 35, a first cooling water discharge passage 36, a drain port 37, and a cooling water temperature control valve 38.

[0044] The water intake 32 is an inlet that takes in water (for example, seawater) outside the vessel propulsion device 1 as cooling water into the vessel propulsion device 1. The water intake 32 is provided in a lower part of the vessel propulsion device 1 that is submerged below the water surface.

[0045] The first cooling water supply passage 33 connects the water intake 32 and the engine cooling mechanism 35, and is a passage through which the cooling water taken in from the water intake 32 flows toward the engine cooling mechanism 35. The first cooling water supply passage 33 is formed by a hole provided in the marine vessel propulsion device 1, or by a pipe or hose attached to the periphery of the engine 4, etc.

[0046] The water pump 34 is a pump that sends cooling water that has flowed into the first cooling water supply passage 33 from outside the marine propulsion device 1 via the water intake 32 toward the engine cooling mechanism 35. The water pump 34 is provided inside the marine propulsion device 1. The water pump 34 is connected to a portion of the first cooling water supply passage 33. As will be described later, a second cooling water supply passage 45 branches off from the first cooling water supply passage 33 at a branch point P located in the first cooling water supply passage 33. The water pump 34 is disposed between the water intake 32 and the branch point P. The water pump 34 is driven by power from the engine 4 or the motor 6. For example, the water pump 34 is attached to a shaft of the power transmission mechanism 11 that is constantly rotated by power from either the engine 4 or the motor 6 while the marine propulsion device 1 is operating; specifically, the transmission shaft 15, and is driven by the rotation of the transmission shaft 15. It should be noted that an electric pump (a pump that has a motor dedicated to driving the pump and is driven by the motor) may be used as the water pump 34. The water pump 34 is a specific example of a "pump".

[0047] The engine cooling mechanism 35 is provided in the engine 4. The engine cooling mechanism 35 is, for example, a cooling jacket or a water jacket, and is configured with cooling passages formed inside or around the engine 4. Cooling water supplied via the first cooling water supply passage 33 flows through the engine cooling mechanism 35, thereby cooling the engine 4.

[0048] The first cooling water discharge passage 36 connects the engine cooling mechanism 35 and the drain outlet 37, and is a passage through which the cooling water that has flowed through the engine cooling mechanism 35 flows toward the drain outlet 37. The first cooling water discharge passage 36 is formed by a hole provided in the marine vessel propulsion device 1, or by a pipe or hose attached to the periphery of the engine 4, etc.

[0049] The drain outlet 37 is an opening for discharging the cooling water after flowing through the engine cooling mechanism 35 and the cooling water after flowing through the heat exchanger 43 to the outside of the marine vessel propulsion device 1. The drain outlet 37 is provided at the rear of the lower part of the marine vessel propulsion device 1.

[0050] The coolant temperature control valve 38 controls the flow rate of the coolant in the first coolant supply passage 33 based on the temperature of the coolant after flowing through the engine cooling mechanism 35. Specifically, the coolant temperature control valve 38 controls the flow rate of the coolant in the first coolant supply passage 33 so that the flow rate of the coolant in the first coolant supply passage 33 increases as the temperature of the coolant after flowing through the engine cooling mechanism 35 increases. The coolant temperature control valve 38 is connected, for example, to the outlet side of the engine cooling mechanism 35 or the inlet side of the first coolant discharge passage 36. The coolant temperature control valve 38 detects the temperature of the coolant after flowing through the engine cooling mechanism 35, i.e., the coolant after cooling the engine 4. The coolant temperature control valve 38 increases its valve opening as the detected coolant temperature increases. The coolant temperature control valve 38 is, for example, a thermostat. The coolant temperature control valve 38 is a specific example of a "flow rate control valve."

[0051] When the amount of heat generated by the engine 4 is large, the temperature of the coolant after flowing through the engine cooling mechanism 35 becomes high. When the temperature of the coolant after flowing through the engine cooling mechanism 35 is high, the valve opening of the coolant temperature control valve 38 becomes large, and the flow rate of the coolant flowing out from the engine cooling mechanism 35 to the first coolant discharge passage 36 increases. As a result, the flow rate of the coolant in the first coolant supply passage 33 and the flow rate of the coolant in the engine cooling mechanism 35 increase. The increase in the flow rate of the coolant in the engine cooling mechanism 35 increases the cooling capacity of the engine 4 by the engine cooling mechanism 35. On the other hand, when the amount of heat generated by the engine 4 is small, the temperature of the coolant after flowing through the engine cooling mechanism 35 becomes low. When the temperature of the coolant after flowing through the engine cooling mechanism 35 is low, the valve opening of the coolant temperature control valve 38 becomes small, and the flow rate of the coolant flowing out from the engine cooling mechanism 35 to the first coolant discharge passage 36 decreases. As a result, the flow rate of the cooling water in the first cooling water supply passage 33 and the flow rate of the cooling water in the engine cooling mechanism 35 decrease. The decrease in the flow rate of the cooling water in the engine cooling mechanism 35 reduces the cooling capacity of the engine 4 by the engine cooling mechanism 35. In this way, the cooling water temperature control valve 38 adjusts the engine cooling capacity of the engine cooling mechanism 35 so that it corresponds to the amount of heat generated by the engine 4.

[0052] The cooling structure 31 also includes a cooling medium circulation passage 39, a cooling medium pump 40, a motor cooling mechanism 41, an inverter cooling mechanism 42, a heat exchanger 43, and a degassing tank 44.

[0053] The cooling medium circulation passage 39 is a passage that circulates the cooling medium between the motor cooling mechanism 41 and the inverter cooling mechanism 42 and the heat exchanger 43. The cooling medium circulation passage 39 is provided inside or around the marine vessel propulsion unit 1. The cooling medium circulation passage 39 is formed by a hole provided in the marine vessel propulsion unit 1, or by a pipe or hose attached around the engine 4, etc. The cooling medium is a liquid, such as a coolant liquid.

[0054] The coolant pump 40 is a pump that circulates the coolant. When the coolant pump 40 is driven, the coolant circulates through the coolant circulation passage 39. The coolant pump 40 is provided midway through the coolant circulation passage 39. The coolant pump 40 is, for example, an electric pump (a pump that has a motor dedicated to driving the pump and is driven by the motor).

[0055] The motor cooling mechanism 41 is provided on the motor 6. The motor cooling mechanism 41 is, for example, a cooling jacket, and is composed of a cooling passage formed inside or around the motor 6. The motor cooling mechanism 41 is also connected to the cooling medium circulation passage 39. The cooling medium circulating in the cooling medium circulation passage 39 flows inside the motor cooling mechanism 41. The motor 6 is cooled by the cooling medium flowing through the motor cooling mechanism 41.

[0056] The inverter cooling mechanism 42 is provided in the inverter 8. The inverter cooling mechanism 42 is, for example, a cooling jacket, and is configured with a cooling passage formed inside or around the inverter 8. The inverter cooling mechanism 42 is also connected to the cooling medium circulation passage 39. The cooling medium circulating in the cooling medium circulation passage 39 flows inside the inverter cooling mechanism 42. The inverter 8 is cooled by the cooling medium flowing through the inverter cooling mechanism 42.

[0057] The heat exchanger 43 is a device that cools the cooling medium circulating in the cooling medium circulation passage 39 by exchanging heat between the cooling medium circulating in the cooling medium circulation passage 39 and the cooling water taken in through the water intake 32. The heat exchanger 43 is provided in the marine propulsion device 1 (see FIG. 1 ). The heat exchanger 43 has a cooling medium flow path and a cooling water flow path. The cooling medium flow path is connected to the cooling medium circulation passage 39. The cooling medium circulating in the cooling medium circulation passage 39 flows within the cooling medium flow path. In addition, as will be described later, the cooling water flow path is connected to the first cooling water supply passage 33 via a second cooling water supply passage 45 branching from the first cooling water supply passage 33. As a result, a portion of the cooling water taken in through the water intake 32 and flowing in the first cooling water supply passage 33 is supplied to the cooling water flow path via the second cooling water supply passage 45 and flows within the cooling water flow path. Heat is exchanged between the cooling medium flowing through the cooling medium flow passage and the cooling water flowing through the cooling water flow passage.

[0058] The degassing tank 44 has a function of separating gas in the cooling medium circulating in the cooling medium circulation passage 39 from the cooling medium, and is connected to the cooling medium circulation passage 39 .

[0059] When the coolant pump 40 is driven, the coolant circulates through the coolant circulation passage 39, during which the coolant flows sequentially through the motor cooling mechanism 41, the inverter cooling mechanism 42, and the coolant flow path of the heat exchanger 43. This cools the motor 6 and the inverter 8. After cooling the motor 6 and the inverter 8, the coolant is further cooled by the heat exchanger 43.

[0060] The cooling structure 31 also includes a second cooling water supply passage 45 , a second cooling water discharge passage 46 , and a pressure valve 47 .

[0061] The second cooling water supply passage 45 is a passage that branches off from the first cooling water supply passage 33 and connects the first cooling water supply passage 33 to the heat exchanger 43. One end of the second cooling water supply passage 45 is connected to a branch point P in the first cooling water supply passage 33, and the other end of the second cooling water supply passage 45 is connected to the cooling water flow path of the heat exchanger 43. The second cooling water supply passage 45 is formed by a hole provided in the marine vessel propulsion device 1, or by a pipe, a hose, or the like attached to the periphery of the engine 4, etc.

[0062] The second cooling water discharge passage 46 is a passage that connects the heat exchanger 43 and the drain port 37. The second cooling water discharge passage 46 connects the cooling water flow path of the heat exchanger 43 and the drain port 37, and allows the cooling water that has flowed through the cooling water flow path of the heat exchanger 43 to flow toward the drain port 37. The second cooling water discharge passage 46 is formed by a hole provided in the marine propulsion device 1, or a pipe or hose attached to the periphery of the engine 4, etc. In this embodiment, the second cooling water discharge passage 46 is connected to the middle of the first cooling water discharge passage 36. The cooling water flowing through the second cooling water discharge passage 46 flows into the first cooling water discharge passage 36 at a confluence point Q, where it merges with the cooling water flowing through the first cooling water discharge passage 36 and flows toward the drain port 37.

[0063] The pressure valve 47 is a valve that controls the inflow of coolant from the first coolant supply passage 33 to the second coolant supply passage 45. Specifically, the pressure valve 47 controls the amount of coolant that flows from the first coolant supply passage 33 to the second coolant supply passage 45 based on the pressure of the coolant in the first coolant supply passage 33. More specifically, the pressure valve 47 controls the amount of coolant that flows from the first coolant supply passage 33 to the second coolant supply passage 45 so that the amount of coolant that flows from the first coolant supply passage 33 to the second coolant supply passage 45 decreases as the pressure of the coolant in the first coolant supply passage 33 increases. The pressure valve 47 is connected, for example, to a branch point P between the first coolant supply passage 33 and the second coolant supply passage 45 or to an inlet side portion of the second coolant supply passage 45. The pressure valve 47 detects the pressure of the cooling water in the first cooling water supply passage 33, and the higher the detected pressure of the cooling water, the smaller the valve opening degree is made.

[0064] In the cooling structure 31, cooling water taken into the marine propulsion device 1 from outside the marine propulsion device 1 through the water intake 32 is distributed and supplied to the engine cooling mechanism 35 and the heat exchanger 43 via the first cooling water supply passage 33 and the second cooling water supply passage 45. When the pressure of the cooling water in the first cooling water supply passage 33 is high, the valve opening of the pressure valve 47 is reduced. This makes it difficult for the cooling water flowing through the first cooling water supply passage 33 to flow into the second cooling water supply passage 45. Therefore, with respect to the cooling water supplied to the engine cooling mechanism 35 and the heat exchanger 43 via the first cooling water supply passage 33 and the second cooling water supply passage 45, the ratio of the amount of cooling water supplied to the engine cooling mechanism 35 to the amount of cooling water supplied to the heat exchanger 43 increases. As a result, the cooling capacity of the engine 4 by the engine cooling mechanism 35 is improved. On the other hand, when the pressure of the cooling water in the first cooling water supply passage 33 is low, the valve opening of the pressure valve 47 is increased. Therefore, the coolant flowing through the first coolant supply passage 33 is more likely to flow into the second coolant supply passage 45. Therefore, in the coolant supplied to the engine cooling mechanism 35 and the heat exchanger 43 via the first coolant supply passage 33 and the second coolant supply passage 45, the ratio of the amount of coolant supplied to the heat exchanger 43 to the amount of coolant supplied to the engine cooling mechanism 35 increases. As a result, the cooling capacity of the coolant by the heat exchanger 43, i.e., the cooling capacity of the heat exchanger 43 for the motor 6 and the inverter 8, increases.

[0065] (Example of ship operation and cooling structure operation) For example, when the boat is operated at low speed, the dog clutch 19 in the power switching mechanism 16 is moved downward so that the rotation of the motor drive shaft 13 is only transmitted to the transmission shaft 15 via the dog clutch 19. The motor 6 is then driven, putting the engine 4 into an idling state. This causes the power of the motor 6 to rotate the transmission shaft 15, driving the water pump 34. As the water pump 34 is driven, cooling water is taken in from outside the boat propulsion device 1 through the water intake 32. The cooling water flows sequentially through the first cooling water supply passage 33, the engine cooling mechanism 35, and the first cooling water discharge passage 36, and is then discharged outside the boat propulsion device 1 through the discharge port 37. Since the engine 4 is idling at this time, the amount of heat generated by the engine 4 is small. Therefore, the temperature of the cooling water after flowing through the engine cooling mechanism 35 is low. When the temperature of the cooling water after flowing through the engine cooling mechanism 35 is low, the valve opening of the cooling water temperature control valve 38 is reduced. As a result, the flow rate of the cooling water in the first cooling water supply passage 33 decreases, the pressure of the cooling water in the first cooling water supply passage 33 decreases, and the valve opening degree of the pressure valve 47 increases. The increased valve opening degree of the pressure valve 47 makes it easier for the cooling water flowing in the first cooling water supply passage 33 to flow into the second cooling water supply passage 45. Therefore, with regard to the cooling water supplied to the engine cooling mechanism 35 and the heat exchanger 43 via the first cooling water supply passage 33 and the second cooling water supply passage 45, the ratio of the amount of cooling water supplied to the heat exchanger 43 to the amount of cooling water supplied to the engine cooling mechanism 35 increases. The cooling water that flows from the first cooling water supply passage 33 into the second cooling water supply passage 45 flows sequentially through the second cooling water supply passage 45, the cooling water flow path of the heat exchanger 43, and the second cooling water discharge passage 46, and is then discharged from the discharge port 37 to the outside of the marine propulsion device 1.

[0066] On the other hand, when the boat is operated at a constant high speed, the dog clutch 19 of the power transmission mechanism 11 is moved upward, so that the rotation of the engine drive shaft 12 is transmitted to the transmission shaft 15 via the dog clutch 19, and the rotation of the motor drive shaft 13 is transmitted to the transmission shaft 15 via the one-way clutch 21. Then, the engine 4 is driven at a constant high speed, and the motor 6 is stopped. This causes the power of the engine 4 to rotate the transmission shaft 15 and drive the water pump 34. As the water pump 34 is driven, cooling water is taken in from outside the boat propulsion device 1 through the water intake port 32. The cooling water flows through the first cooling water supply passage 33, the engine cooling mechanism 35, and the first cooling water discharge passage 36, and is then discharged outside the boat propulsion device 1 through the discharge port 37. At this time, the engine 4 is driven at a high speed, so the amount of heat generated by the engine 4 is large. Therefore, the temperature of the cooling water after flowing through the engine cooling mechanism 35 is high. When the temperature of the coolant after flowing through the engine cooling mechanism 35 is high, the valve opening of the coolant temperature control valve 38 increases. As a result, the flow rate of the coolant in the first coolant supply passage 33 increases, the pressure of the coolant in the first coolant supply passage 33 increases, and the valve opening of the pressure valve 47 decreases. Because the valve opening of the pressure valve 47 decreases, the coolant flowing through the first coolant supply passage 33 is less likely to flow into the second coolant supply passage 45. Therefore, with respect to the coolant supplied to the engine cooling mechanism 35 and the heat exchanger 43 via the first coolant supply passage 33 and the second coolant supply passage 45, the ratio of the amount of coolant supplied to the engine cooling mechanism 35 to the amount of coolant supplied to the heat exchanger 43 increases. The cooling water that flows from the first cooling water supply passage 33 into the second cooling water supply passage 45 flows through the second cooling water supply passage 45, the cooling water flow path of the heat exchanger 43, and the second cooling water discharge passage 46, and is then discharged outside the marine propulsion unit 1 through the discharge port 37.

[0067] On the other hand, when the boat is accelerated and planed, the dog clutch 19 of the power transmission mechanism 11 is moved upward, so that the rotation of the engine drive shaft 12 is transmitted to the transmission shaft 15 via the dog clutch 19, and the rotation of the motor drive shaft 13 is transmitted to the transmission shaft 15 via the one-way clutch 21. The engine 4 and the motor 6 are then driven, increasing their respective rotation speeds. This causes the power of the engine 4 and the motor 6 to rotate the transmission shaft 15, which drives the water pump 34. As the water pump 34 is driven, cooling water is taken in from outside the boat propulsion device 1 through the water intake port 32. The water pump 34 then flows through the first cooling water supply passage 33, the engine cooling mechanism 35, and the first cooling water discharge passage 36, and is then discharged outside the boat propulsion device 1 through the discharge port 37. At this time, the rotation speed of the engine 4 is increasing, so the amount of heat generated by the engine 4 increases. Therefore, the temperature of the cooling water after flowing through the engine cooling mechanism 35 increases. When the temperature of the coolant after flowing through the engine cooling mechanism 35 is high, the valve opening of the coolant temperature control valve 38 increases. As a result, the flow rate of the coolant in the first coolant supply passage 33 increases, the pressure of the coolant in the first coolant supply passage 33 increases, and the valve opening of the pressure valve 47 decreases. Because the valve opening of the pressure valve 47 decreases, the coolant flowing through the first coolant supply passage 33 is less likely to flow into the second coolant supply passage 45. Therefore, with respect to the coolant supplied to the engine cooling mechanism 35 and the heat exchanger 43 via the first coolant supply passage 33 and the second coolant supply passage 45, the ratio of the amount of coolant supplied to the engine cooling mechanism 35 to the amount of coolant supplied to the heat exchanger 43 increases. The cooling water that flows from the first cooling water supply passage 33 into the second cooling water supply passage 45 flows through the second cooling water supply passage 45, the cooling water flow path of the heat exchanger 43, and the second cooling water discharge passage 46, and is then discharged outside the marine propulsion unit 1 through the discharge port 37.

[0068] Thus, in the cooling structure 31, when the vessel is operating at low speed, i.e., when the motor 6 is driving and the engine 4 is idling, the ratio of the amount of cooling water supplied to the heat exchanger 43 to the amount of cooling water supplied to the engine cooling mechanism 35 increases. As a result, the cooling capacity of the cooling medium by the heat exchanger 43 is higher than the cooling capacity of the cooling medium by the heat exchanger 43 when the vessel is operating at a constant high speed or planing. At the same time, the engine cooling capacity of the engine cooling mechanism 35 is lower than the cooling capacity of the engine cooling mechanism 35 when the vessel is operating at a constant high speed or planing. When the motor 6 is operating at low speed, the motor 6 and the inverter 8 generate heat, causing the temperature of the cooling medium to rise. By increasing the amount of cooling water supplied to the heat exchanger 43 during low speed operation of the vessel and increasing the cooling capacity of the cooling medium by the heat exchanger 43, the temperature rise of the cooling medium can be quickly and reliably suppressed. On the other hand, when the engine 4 is idling during low speed operation of the vessel, the amount of heat generated by the engine 4 is small. By reducing the amount of cooling water supplied to the engine cooling mechanism 35 when the vessel is operating at low speed and lowering the cooling capacity of the engine 4 by the engine cooling mechanism 35, excessive cooling of the engine 4 can be avoided.

[0069] On the other hand, in the cooling structure 31, when the ship is operating at a constant high speed, i.e., when the engine 4 is operating at a high speed and the motor 6 is stopped, the ratio of the amount of cooling water supplied to the engine cooling mechanism 35 to the amount of cooling water supplied to the heat exchanger 43 increases. As a result, the engine cooling capacity of the engine cooling mechanism 35 is higher than the engine cooling capacity of the engine cooling mechanism 35 when the ship is operating at a low speed. At the same time, the cooling capacity of the cooling medium supplied by the heat exchanger 43 is lower than the cooling capacity of the cooling medium supplied by the heat exchanger 43 when the ship is operating at a low speed. When the engine 4 is operating at a high speed during constant high speed operation of the ship, the amount of heat generated by the engine 4 increases. By increasing the amount of cooling water supplied to the engine cooling mechanism 35 during constant high speed operation of the ship and increasing the cooling capacity of the engine 4 by the engine cooling mechanism 35, the engine 4 can be cooled quickly and reliably. On the other hand, when the motor 6 is stopped during constant high speed operation of the ship, the motor 6 and the inverter 8 do not generate heat. Therefore, when the ship is operating at a constant high speed, there is no problem in reducing the amount of cooling water supplied to the heat exchanger 43 and lowering the cooling capacity of the cooling medium by the heat exchanger 43.

[0070] On the other hand, in the cooling structure 31, when the vessel is planing, i.e., when the engine 4 and motor 6 are operating and the rotational speeds of the engine 4 and motor 6 are increasing, the ratio of the amount of cooling water supplied to the engine cooling mechanism 35 to the amount of cooling water supplied to the heat exchanger 43 increases, as in the case when the vessel is operating at a constant high speed. As a result, the engine cooling capacity of the engine cooling mechanism 35 is higher than the engine cooling capacity of the engine cooling mechanism 35 when the vessel is operating at a low speed. At the same time, the cooling capacity of the cooling medium supplied by the heat exchanger 43 is lower than the cooling capacity of the cooling medium supplied by the heat exchanger 43 when the vessel is operating at a low speed. When the engine 4 is operating at a high rotational speed while the vessel is planing, the amount of heat generated by the engine 4 increases. By increasing the amount of cooling water supplied to the engine cooling mechanism 35 while the vessel is planing and increasing the cooling capacity of the engine 4 by the engine cooling mechanism 35, the engine 4 can be cooled quickly and reliably. On the other hand, when the motor 6 is operating at a high rotational speed while the vessel is planing, the motor 6 and the inverter 8 generate heat. However, the duration of planing of the vessel when the vessel is planing is shorter than the duration of constant high-speed operation when the vessel is operating at a constant speed. Therefore, the amount of heat generated by the motor 6 and the inverter 8 when the vessel is planing is not very large. Therefore, even if the amount of cooling water supplied to the heat exchanger 43 is reduced when the vessel is planing, the heat exchanger 43 can suppress the temperature rise of the cooling medium, thereby sufficiently cooling the motor 6 and the inverter 8. For example, by using a heat exchanger with a large heat capacity as the heat exchanger 43 or by using a cooling medium with a large heat capacity as the cooling medium flowing through the cooling medium circulation passage 39, the motor 6 and the inverter 8 can be sufficiently cooled when the amount of cooling water supplied to the heat exchanger 43 is reduced when the vessel is planing.

[0071] As described above, in the marine propulsion device 1 according to the first embodiment of the present invention, the cooling water after flowing through the engine cooling mechanism 35 flows through the first cooling water discharge passage 36 and is then discharged from the water outlet 37 to the outside of the marine propulsion device 1. Therefore, the cooling water after flowing through the engine cooling mechanism 35 does not flow through the cooling water flow path of the heat exchanger 43, and therefore the cooling water whose temperature has increased by flowing through the engine cooling mechanism 35 does not flow through the cooling water flow path of the heat exchanger 43. Furthermore, the cooling water after flowing through the cooling water flow path of the heat exchanger 43 flows through the second cooling water discharge passage 46 and is then discharged from the water outlet 37 to the outside of the marine propulsion device 1. Therefore, the cooling water after flowing through the cooling water flow path of the heat exchanger 43 does not flow through the engine cooling mechanism 35, and therefore the cooling water whose temperature has increased by flowing through the cooling water flow path of the heat exchanger 43 does not flow through the engine cooling mechanism 35. Therefore, according to the marine propulsion device 1 of this embodiment, it is easy to cool the engine 4 and the heat exchanger 43 individually, and therefore the two power sources, i.e., the engine 4 and the motor 6, can be appropriately cooled separately.

[0072] The marine vessel propulsion device 1 of this embodiment also includes a pressure valve 47 that controls the flow of cooling water from the first cooling water supply passage 33 to the second cooling water supply passage 45, and the pressure valve 47 can change the ratio between the amount of cooling water supplied to the engine cooling mechanism 35 and the amount of cooling water supplied to the heat exchanger 43. In this way, the marine vessel propulsion device 1 of this embodiment makes it easy to individually set the amount of cooling water supplied to the engine cooling mechanism 35 and the amount of cooling water supplied to the heat exchanger 43, and therefore the two power sources, i.e., the engine 4 and the motor 6, can be appropriately cooled separately.

[0073] Furthermore, in the marine propulsion device 1 of this embodiment, the cooling water temperature control valve 38 controls the flow rate of the cooling water in the first cooling water supply passage 33 so that the flow rate of the cooling water in the first cooling water supply passage 33 increases as the temperature of the cooling water after cooling the engine 4 increases. Furthermore, the pressure valve 47 controls the amount of cooling water flowing from the first cooling water supply passage 33 to the second cooling water supply passage 45 so that the amount of cooling water flowing from the first cooling water supply passage 33 to the second cooling water supply passage 45 decreases as the pressure of the cooling water in the first cooling water supply passage 33 increases. As described above, when the engine 4 is driven at high speed during constant high-speed operation of the marine vessel, the amount of heat generated by the engine 4 increases, and the temperature of the cooling water after cooling the engine 4 increases. When the temperature of the cooling water after cooling the engine 4 increases, the flow rate of the cooling water in the first cooling water supply passage 33 increases through control of the cooling water temperature control valve 38, and the pressure of the cooling water in the first cooling water supply passage 33 increases. When the pressure of the cooling water in the first cooling water supply passage 33 becomes high, the pressure valve 47 controls the cooling water so that it is more difficult for the cooling water to flow from the first cooling water supply passage 33 to the second cooling water supply passage 45. This increases the ratio of the amount of cooling water supplied to the engine cooling mechanism 35 to the amount of cooling water supplied to the heat exchanger 43, thereby increasing the cooling capacity of the engine 4 by the engine cooling mechanism 35. In this way, when the vessel is operating at a constant high speed, the cooling capacity of the engine 4 by the engine cooling mechanism 35 can be increased by the cooperation of the cooling water temperature control valve 38 and the pressure valve 47, thereby quickly and reliably cooling the engine 4, which generates increased heat due to high rotation speed. Furthermore, as described above, when the engine 4 is idled and the motor 6 is driven during low-speed operation of the vessel, the amount of heat generated by the engine 4 decreases, and the temperature of the cooling water after cooling the engine 4 decreases. When the temperature of the cooling water after cooling the engine 4 becomes low, the flow rate of the cooling water in the first cooling water supply passage 33 is reduced by control of the cooling water temperature control valve 38, and the pressure of the cooling water in the first cooling water supply passage 33 is reduced.When the pressure of the cooling water in the first cooling water supply passage 33 becomes low, the pressure valve 47 controls so that the cooling water more easily flows from the first cooling water supply passage 33 to the second cooling water supply passage 45, increasing the ratio of the amount of cooling water supplied to the heat exchanger 43 to the amount of cooling water supplied to the engine cooling mechanism 35, and increasing the cooling capacity of the cooling medium by the heat exchanger 43. In this way, when the ship is operating at low speed, the cooling water temperature control valve 38 and the pressure valve 47 work together to increase the cooling capacity of the cooling medium by the heat exchanger 43, allowing the cooling medium that has risen in temperature due to heat generated by the motor 6 and the inverter 8 to be quickly and reliably cooled, and the motor 6 to be quickly and reliably cooled via that cooling medium.

[0074] Furthermore, in the marine vessel propulsion device 1 of this embodiment, the motor cooling mechanism 41 and the inverter cooling mechanism 42 are connected to the coolant circulation passage 39, and the coolant flows through the motor cooling mechanism 41 and the inverter cooling mechanism 42. This allows the coolant to quickly and reliably cool not only the motor 6 but also the inverter 8. [Example]

[0075] 5 shows a cooling structure 61 in a marine vessel propulsion device 51 according to a second embodiment of the present invention. In the marine vessel propulsion device 51 according to the second embodiment of the present invention, the same components as those in the marine vessel propulsion device 1 according to the first embodiment of the present invention are designated by the same reference numerals, and their description will be omitted or simplified.

[0076] The cooling structure 31 in the marine propulsion unit 1 of the first embodiment of the present invention described above is configured to circulate a cooling medium between the motor cooling mechanism 41 and the inverter cooling mechanism 42 and the heat exchanger 43 to cool the motor 6 and the inverter 8, while supplying cooling water taken in through the water intake 32 to the heat exchanger 43, which then cools the cooling medium, thereby indirectly cooling the motor 6 and the inverter 8. In contrast, the cooling structure 61 in the marine propulsion unit 51 of the second embodiment of the present invention is configured to directly cool the motor 6 and the inverter 8 by supplying cooling water taken in through the water intake 32 to the motor cooling mechanism 41 and the inverter cooling mechanism 42.

[0077] As shown in FIG. 5 , in a cooling structure 61, a second cooling water supply passage 62 branches off from the first cooling water supply passage 33 and connects the first cooling water supply passage 33 and the motor cooling mechanism 41. One end of the second cooling water supply passage 62 is connected to a branch point P in the first cooling water supply passage 33, and the other end of the second cooling water supply passage 62 is connected to the motor cooling mechanism 41. The motor cooling mechanism 41 and the inverter cooling mechanism 42 are connected by a third cooling water supply passage 63. The second cooling water discharge passage 64 is a passage that connects the inverter cooling mechanism 42 and the drain port 37. One end of the second cooling water discharge passage 64 is connected to the inverter cooling mechanism 42, and the other end of the second cooling water discharge passage 64 is connected to a junction point Q in the first cooling water discharge passage 36. In addition, a pressure valve 47 that controls the inflow of cooling water from the first cooling water supply passage 33 to the second cooling water supply passage 62 is connected to the branch point P between the first cooling water supply passage 33 and the second cooling water supply passage 62 or to the inlet side portion of the second cooling water supply passage 62.

[0078] In the cooling structure 61, when the water pump 34 is driven, cooling water taken in from outside the marine propulsion unit 51 through the water intake 32 flows sequentially through the first cooling water supply passage 33, the engine cooling mechanism 35, and the first cooling water discharge passage 36, and is then discharged from the discharge port 37 to outside the marine propulsion unit 51. In addition, a portion of the cooling water taken in from outside the marine propulsion unit 51 through the water intake 32 by driving the water pump 34 flows from the first cooling water supply passage 33 into the second cooling water supply passage 62, flows sequentially through the second cooling water supply passage 62, the motor cooling mechanism 41, the third cooling water supply passage 63, the inverter cooling mechanism 42, and the second cooling water discharge passage 64, and is then discharged from the discharge port 37 to outside the marine propulsion unit 51.

[0079] In the marine vessel propulsion device 51 of the second embodiment of the present invention having this configuration, cooling water that has been heated by flowing through the engine cooling mechanism 35 does not flow through the motor cooling mechanism 41, and cooling water that has been heated by flowing through the motor cooling mechanism 41 does not flow through the engine cooling mechanism 35. Therefore, with the marine vessel propulsion device 51 of the second embodiment, it is easy to cool the engine 4 and the motor 6 individually, and therefore the two power sources, i.e., the engine 4 and the motor 6, can be appropriately cooled separately.

[0080] Furthermore, in the marine vessel propulsion device 51 of the second embodiment, the pressure valve 47 can be used to change the ratio between the amount of cooling water supplied to the engine cooling mechanism 35 and the amount of cooling water supplied to the motor cooling mechanism 41. In this way, with the marine vessel propulsion device 51 of the second embodiment, it is easy to individually set the amount of cooling water supplied to the engine cooling mechanism 35 and the amount of cooling water supplied to the motor cooling mechanism 41, and therefore the two power sources, i.e., the engine 4 and the motor 6, can be appropriately cooled separately.

[0081] Furthermore, according to the marine vessel propulsion device 51 of the second embodiment, as with the marine vessel propulsion device 1 of the first embodiment, the cooling water temperature control valve 38 and the pressure valve 47 work together to quickly and reliably cool the engine 4, which has increased heat generation due to being driven at high speeds when the marine vessel is operating at a constant high speed, and also to quickly and reliably cool the motor 6 and inverter 8, which have generated heat due to being driven when the marine vessel is operating at a low speed.

[0082] In the above embodiments, the first power source is the engine 4 and the second power source is the motor 6, but the present invention is not limited to this. The marine vessel propulsion device may be provided with two motors for rotating the propellers, with one motor serving as the first power source and the other as the second power source.

[0083] In the present invention, the valve that controls the inflow of cooling water from the first cooling water supply passage to the second cooling water supply passage is not limited to a pressure valve.

[0084] In addition, in each of the above embodiments, an example was given in which the first cooling water discharge passage 36 and the second cooling water discharge passage 46 (64) are connected to a common drain outlet 37, but it is also possible to provide two drain outlets in the marine propulsion device, connect the first cooling water discharge passage 36 to one of the drain outlets, and connect the second cooling water discharge passage 46 (64) to the other drain outlet.

[0085] The present invention can also be applied to other types of marine propulsion devices other than outboard motors.

[0086] 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]

[0087] 1, 51 Ship propulsion equipment 2 propellers 4 Engine (primary power source) 6 Motor (second power source) 8 inverters 31, 61 Cooling structure 32 Water Intake 33 First cooling water supply passage 34 Water pump (pump) 35 Engine cooling mechanism 36 First cooling water discharge passage 37 Drain port 38 Cooling water temperature control valve (flow control valve) 39 Cooling medium circulation passage 41 Motor cooling mechanism 42 Inverter cooling mechanism 43 Heat exchanger 45, 62 Second cooling water supply passage 46, 64 Second cooling water discharge passage 47 Pressure Valve

Claims

1. A marine vessel propulsion device for propelling a marine vessel, a first power source that rotates the propeller; a second power source that rotates the propeller; and The water intake and a first cooling water supply passage connecting the water intake and the first power source; a pump that sends water that flows into the first cooling water supply passage from outside the marine propulsion device through the water intake as cooling water toward the first power source; The drain and a first cooling water discharge passage connecting the first power source and the drain port; A heat exchanger; a cooling medium circulation passage for circulating a cooling medium between the second power source and the heat exchanger; a second cooling water supply passage branching from the first cooling water supply passage and connecting the first cooling water supply passage and the heat exchanger; a second cooling water discharge passage connecting the heat exchanger and the discharge port;

2. 2. The marine vessel propulsion device according to claim 1, further comprising a valve that controls the flow of cooling water from the first cooling water supply passage to the second cooling water supply passage.

3. a flow control valve that controls the flow rate of the cooling water in the first cooling water supply passage based on the temperature of the cooling water after cooling the first power source; a pressure valve that controls the amount of cooling water that flows from the first cooling water supply passage to the second cooling water supply passage based on the pressure of the cooling water in the first cooling water supply passage, 2. The marine propulsion device according to claim 1, wherein the flow rate control valve controls the flow rate of the cooling water in the first cooling water supply passage so that the flow rate of the cooling water in the first cooling water supply passage increases as the temperature of the cooling water after cooling the first power source increases, and the pressure valve controls the amount of cooling water flowing from the first cooling water supply passage to the second cooling water supply passage so that the amount of cooling water flowing from the first cooling water supply passage to the second cooling water supply passage decreases as the pressure of the cooling water in the first cooling water supply passage increases.

4. a motor as the second power source; an inverter for controlling the driving of the motor, 2. The marine propulsion device according to claim 1, wherein the cooling medium circulation passage is a passage for circulating the cooling medium between the motor and the inverter and the heat exchanger.

5. A marine vessel propulsion device for propelling a marine vessel, a first power source that rotates the propeller; a second power source that rotates the propeller; and The water intake and a first cooling water supply passage connecting the water intake and the first power source; a pump that sends water that flows into the first cooling water supply passage from outside the marine propulsion device through the water intake as cooling water toward the first power source; The drain and a first cooling water discharge passage connecting the first power source and the drain port; a second cooling water supply passage branching from the first cooling water supply passage and connecting the first cooling water supply passage and the second power source; a second cooling water discharge passage connecting the second power source and the discharge port.

6. 6. A marine vessel propulsion device according to claim 5, further comprising a valve that controls the flow of cooling water from the first cooling water supply passage to the second cooling water supply passage.

7. a flow control valve that controls the flow rate of the cooling water in the first cooling water supply passage based on the temperature of the cooling water after cooling the first power source; a pressure valve that controls the amount of cooling water that flows from the first cooling water supply passage to the second cooling water supply passage based on the pressure of the cooling water in the first cooling water supply passage, 6. The marine propulsion device according to claim 5, wherein the flow rate control valve controls the flow rate of the cooling water in the first cooling water supply passage so that the flow rate of the cooling water in the first cooling water supply passage increases as the temperature of the cooling water after cooling the first power source increases, and the pressure valve controls the amount of cooling water flowing from the first cooling water supply passage to the second cooling water supply passage so that the amount of cooling water flowing from the first cooling water supply passage to the second cooling water supply passage decreases as the pressure of the cooling water in the first cooling water supply passage increases.

8. a motor as the second power source; an inverter for controlling the driving of the motor, the second cooling water supply passage is a passage that connects the first cooling water supply passage with the motor and the inverter, 6. A marine propulsion device according to claim 5, wherein the second cooling water discharge passage is a passage that connects the motor and the inverter with the drain port.

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