SHIP PROPULSION MACHINE

Abstract

A ship propulsion machine includes a first and second power sources for rotating a propeller, an intake port, a first cooling water supply passage connecting the intake port to the first power source, a pump that sends water flowed into the first cooling water supply passage from outside of the ship propulsion machine via the intake port toward the first power source as cooling water, a drain port, a first cooling water discharge passage connecting the first power source to the drain port 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 branched from the first cooling water supply passage and connecting the first cooling water supply passage to the heat exchanger, and a second cooling water discharge passage connecting the heat exchanger to the drain port.

Claims

1. A ship propulsion machine for propelling a boat, the ship propulsion machine comprising: a first power source for rotating a propeller; a second power source for rotating the propeller; an intake port; a first cooling water supply passage connecting the intake port to the first power source; a pump configured to send water flowed into the first cooling water supply passage from outside of the ship propulsion machine via the intake port toward the first power source as cooling water; a drain port; a first cooling water discharge passage connecting the first power source to the drain port; a heat exchanger; a cooling medium circulation passage configured to circulate a cooling medium between the second power source and the heat exchanger; a second cooling water supply passage branched from the first cooling water supply passage and connecting the first cooling water supply passage to the heat exchanger; and a second cooling water discharge passage connecting the heat exchanger to the drain port.

2. The ship propulsion machine according to claim 1, further comprising: a valve configured to control inflow of the cooling water from the first cooling water supply passage to the second cooling water supply passage.

3. The ship propulsion machine according to claim 1, further comprising: a flow rate control valve configured to control a flow rate of the cooling water in the first cooling water supply passage based on a temperature of the cooling water after cooling the first power source; and a pressure valve configured to control an amount of the cooling water flowing from the first cooling water supply passage into the second cooling water supply passage based on a pressure of the cooling water in the first cooling water supply passage, 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 rises, and the pressure valve controls the amount of the cooling water flowing from the first cooling water supply passage to the second cooling water supply passage so that the amount of the 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. The ship propulsion machine according to claim 1, further comprising: a motor as the second power source; and an inverter configured to control driving of the motor, wherein the cooling medium circulation passage is a passage that circulates the cooling medium between the motor and the inverter and the heat exchanger.

5. The ship propulsion machine according to claim 1, further comprising: a degassing tank configured to separate gas contained in the cooling medium that circulates in the cooling medium circulation passage.

6. A ship propulsion machine for propelling a boat, the ship propulsion machine comprising: a first power source for rotating a propeller; a second power source for rotating the propeller; an intake port; a first cooling water supply passage connecting the intake port to the first power source; a pump configured to send water flowed into the first cooling water supply passage from outside of the ship propulsion machine via the intake port toward the first power source as cooling water; a drain port; a first cooling water discharge passage connecting the first power source to the drain port; a second cooling water supply passage branched from the first cooling water supply passage and connecting the first cooling water supply passage to the second power source; and a second cooling water discharge passage connecting the second power source to the drain port.

7. The ship propulsion machine according to claim 6, further comprising: a valve configured to control inflow of the cooling water from the first cooling water supply passage to the second cooling water supply passage.

8. The ship propulsion machine according to claim 6, further comprising: a flow rate control valve configured to control a flow rate of the cooling water in the first cooling water supply passage based on a temperature of the cooling water after cooling the first power source; and a pressure valve configured to control an amount of the cooling water flowing from the first cooling water supply passage into the second cooling water supply passage based on a pressure of the cooling water in the first cooling water supply passage, 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 rises, and the pressure valve controls the amount of the cooling water flowing from the first cooling water supply passage to the second cooling water supply passage so that the amount of the 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.

9. The ship propulsion machine according to claim 6, further comprising: a motor as the second power source; and an inverter configured to control driving of the motor, wherein the second cooling water supply passage is a passage connecting the first cooling water supply passage to the motor and the inverter, and the second cooling water discharge passage is a passage connecting the motor and the inverter to the drain port.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0027] FIG. 1 is an explanatory diagram illustrating a ship propulsion machine according to a first embodiment of the present invention.

[0028] FIG. 2 is an explanatory diagram illustrating a power transmission mechanism in the ship propulsion machine according to the first embodiment of the present invention.

[0029] FIGS. 3A and 3B are explanatory diagrams illustrating a power switching mechanism in the power transmission mechanism of the ship propulsion machine according to the first embodiment of the present invention.

[0030] FIG. 4 is an explanatory diagram illustrating a cooling structure in the ship propulsion machine according to the first embodiment of the present invention.

[0031] FIG. 5 is an explanatory diagram illustrating a cooling structure in a ship propulsion machine according to a second embodiment of the present invention.

DETAILED DESCRIPTION OF EXEMPLIFIED EMBODIMENTS

[0032] Regardless of whether the power source is an engine or a motor, cooling of the power source is important to improve durability or performance of the power source. To improve cooling efficiency of the power source, it is preferable to adopt a liquid cooling method rather than an air cooling method.

[0033] 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 flowed in the cooling passage of the power source, thereby cooling the power source.

[0034] When attention is focused on a method of supplying a cooling liquid to a power source provided with a cooling passage, a liquid cooling method is classified into a direct cooling method or an indirect cooling method. The direct cooling method is a method in which water (for example, seawater) outside a ship propulsion machine is directly supplied to a power source to cool the power source. The indirect cooling method is a method in which a circulation path for circulating a cooling liquid is formed inside a ship propulsion machine, a power source and a heat exchanger are connected to the circulation path, water from outside of the ship propulsion machine is supplied to the heat exchanger to cool the cooling liquid circulating through the circulation path, and the power source is cooled by the cooling liquid.

[0035] In a ship propulsion machine including a plurality of power sources, it is desirable to cool each power source by a liquid cooling method. When each power source is cooled by the liquid cooling method, a cooling passage is provided inside or around each power source, and a supply passage for supplying a cooling liquid to each power source is provided inside or around the ship propulsion machine.

[0036] Here, in the ship propulsion machine including the plurality of power sources, when the plurality of power sources are switched depending on a boat operation mode or the like, an amount of heat generated by each of the plurality of power sources differs for each power source depending on the boat operation mode or the like. Therefore, it is necessary to appropriately cool each of the plurality of power sources. Therefore, it is necessary to construct a supply passage for supplying a cooling liquid to each power source so that each of the plurality of power sources can be easily cooled appropriately.

[0037] Here, in a ship propulsion machine including a plurality of power sources, when a supply passage is constructed so that a cooling liquid is supplied to a first power source and the cooling liquid after flowing in a cooling passage of the first power source is supplied to a second power source, it is difficult to properly cool each of the first power source and the second power source because the cooling water that was heated by flowing in the cooling passage of the first power source will be supplied to the second power source so that the first power source may be over-cooled and the second power source may be insufficiently cooled. When a supply passage is constructed so that a cooling liquid is supplied to a first power source and the cooling liquid after flowing in a cooling passage of the first power source is supplied to a second power source, it is difficult to appropriately cool each of the first power source and the second power source because it becomes difficult to respectively change an amount of the cooling liquid supplied to the first power source and an amount of the cooling liquid supplied to the second power source.

[0038] JP2007-8329A describes engine cooling but does not describe motor cooling.

[0039] The present invention is made considering, for example, the problems described above, and an object of the present invention is to provide a ship propulsion machine including a plurality of power sources for rotating a propeller, in which each of the plurality of power sources is appropriately cooled.

[0040] A ship propulsion machine according to a first embodiment of the present invention is a ship propulsion machine for propelling a boat, and includes a first power source for rotating a propeller and a second power source for rotating the propeller.

[0041] The ship propulsion machine of the first embodiment includes an intake port, a first cooling water supply passage that connects the intake port to the first power source, a pump that sends water flowed into the first cooling water supply passage from outside of the ship propulsion machine via the intake port toward the first power source as cooling water, a drain port, and a first cooling water discharge passage connecting the first power source to the drain port.

[0042] The ship propulsion machine 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 branched from the first cooling water supply passage and connecting the first cooling water supply passage to the heat exchanger, and a second cooling water discharge passage connecting the heat exchanger to the drain port.

[0043] In the ship propulsion machine of the first embodiment having such configuration, water flowed into the first cooling water supply passage from outside of the ship propulsion machine via the intake port by driving the pump flows in the first cooling water supply passage toward the first power source as cooling water. For example, a cooling passage is formed inside or around the first power source. The cooling water flowed in the first cooling water supply passage then flows in a cooling passage of the first power source. Accordingly, the first power source is cooled. The cooling water flowed in the cooling passage of the first power source then flows in the first cooling water discharge passage toward the drain port, and is then discharged to outside of the ship propulsion machine from the drain port.

[0044] By driving the pump, a part of the cooling water flowing in the first cooling water supply passage flows into the second cooling water supply passage branched from the first cooling water supply passage, and flows in the second cooling water supply passage toward the heat exchanger. The cooling water flowed in the second cooling water supply passage then flows in the heat exchanger. As a result, the cooling medium that circulates between the second power source and the heat exchanger is cooled by the heat exchanger. The cooling water flowed in the heat exchanger then flows in the second cooling water discharge passage toward the drain port, and is then discharged to outside of the ship propulsion machine from the drain port.

[0045] The second power source and the heat exchanger are each connected to the cooling medium circulation passage. The cooling medium cooled by the heat exchanger flows in the cooling medium circulation passage, thereby circulating between the heat exchanger and the second power source. For example, a cooling passage is formed inside or around the second power source. The cooling medium flows in the cooling passage of the second power source while circulating between the second power source and the heat exchanger. Accordingly, the second power source is cooled. 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.

[0046] In the ship propulsion machine of the first embodiment, the cooling water after flowing in the cooling passage of the first power source flows in the first cooling water discharge passage, and is then discharged to outside of the ship propulsion machine from the drain port. Therefore, the cooling water after flowing in the cooling passage of the first power source does not flow in the heat exchanger, and accordingly, the cooling water heated by flowing in the cooling passage of the first power source does not flow in the heat exchanger. The cooling water after flowing in the heat exchanger flows in the second cooling water discharge passage, and is then discharged to outside of the ship propulsion machine from the drain port. Therefore, the cooling water after flowing in the heat exchanger does not flow in the cooling passage of the first power source, and accordingly, the cooling water heated by flowing in the heat exchanger does not flow in the cooling passage of the first power source. Therefore, according to the ship propulsion machine of the embodiment, it is easy to individually cool the first power source and the heat exchanger, and accordingly, each of the first power source and the second power source can be appropriately cooled. Specifically, for example, it is possible to prevent the first power source from being over-cooled while preventing the second power source from being insufficiently cooled, thereby appropriately cooling each power source.

[0047] In the ship propulsion machine of the first embodiment, it is technically easy to provide a valve that controls inflow of the cooling water from the first cooling water supply passage to the second cooling water supply passage, for example, at a branch point between the first cooling water supply passage and the second cooling water supply passage. By providing such valve, it is possible to change a ratio between an amount of the cooling water supplied to the first power source and an amount of the cooling water supplied to the heat exchanger. Thus, according to the ship propulsion machine of the first embodiment of the present invention, it is easy to individually set the amount of the cooling water supplied to the first power source and the amount of the cooling water supplied to the heat exchanger, and accordingly, each of the first power source and the second power source can be appropriately cooled. For example, when the first power source is driven and the second power source is stopped, the ratio of the amount of the cooling water supplied to the first power source to the amount of the cooling water supplied to the heat exchanger can be increased, and cooling of the first power source can be prioritized over cooling of the second power source.

[0048] A ship propulsion machine according to a second embodiment of the present invention is a ship propulsion machine for propelling a boat, and includes a first power source for rotating a propeller and a second power source for rotating the propeller.

[0049] The ship propulsion machine of the second embodiment includes an intake port, a first cooling water supply passage that connects the intake port to the first power source, a pump that sends water flowed into the first cooling water supply passage from outside of the ship propulsion machine via the intake port toward the first power source as cooling water, a drain port, and a first cooling water discharge passage connecting the first power source to the drain port.

[0050] The ship propulsion machine of the second embodiment includes a second cooling water supply passage branched from the first cooling water supply passage and connecting the first cooling water supply passage to the second power source, and a second cooling water discharge passage connecting the second power source to the drain port.

[0051] In the ship propulsion machine of the second embodiment having such configuration, water flowed into the first cooling water supply passage from outside of the ship propulsion machine via the intake port by driving the pump flows in the first cooling water supply passage toward the first power source as cooling water. The cooling water flowed in the first cooling water supply passage then flows in a cooling passage of the first power source. Accordingly, the first power source is cooled. The cooling water flowed in the cooling passage of the first power source then flows in the first cooling water discharge passage toward the drain port, and is then discharged to outside of the ship propulsion machine from the drain port.

[0052] By driving the pump, a part of the cooling water flowing in the first cooling water supply passage flows into the second cooling water supply passage branched from the first cooling water supply passage, and flows in the second cooling water supply passage toward the second power source. The cooling water flowed in the second cooling water supply passage then flows in a cooling passage of the second power source. Accordingly, the second power source is cooled. The cooling water flowed in the cooling passage of the second power source then flows in the second cooling water discharge passage toward the drain port, and is then discharged to outside of the ship propulsion machine from the drain port.

[0053] In the ship propulsion machine of the second embodiment, the cooling water after flowing in the cooling passage of the first power source flows in the first cooling water discharge passage, and is then discharged to outside of the ship propulsion machine from the drain port. Therefore, the cooling water after flowing in the cooling passage of the first power source does not flow in the cooling passage of the second power source, and accordingly, the cooling water heated by flowing in the cooling passage of the first power source does not flow in the cooling passage of the second power source. The cooling water after flowing in the cooling passage of the second power source flows in the second cooling water discharge passage, and is then discharged to outside of the ship propulsion machine from the drain port. Therefore, the cooling water after flowing in the cooling passage of the second power source does not flow in the cooling passage of the first power source, and accordingly, the cooling water heated by flowing in the cooling passage of the second power source does not flow in the cooling passage of the first power source. Therefore, according to the ship propulsion machine of the embodiment, it is easy to individually cool the first power source and the second power source, and accordingly, each of the first power source and the second power source can be appropriately cooled.

[0054] In the ship propulsion machine of the second embodiment, it is technically easy to provide a valve that controls inflow of the cooling water from the first cooling water supply passage to the second cooling water supply passage, for example, at a branch point between the first cooling water supply passage and the second cooling water supply passage. By providing such valve, it is possible to change a ratio between an amount of the cooling water supplied to the first power source and an amount of the cooling water supplied to the second power source. Thus, according to the ship propulsion machine of the second embodiment of the present invention, it is easy to individually set the amount of the cooling water supplied to the first power source and the amount of the cooling water supplied to the second power source, and accordingly, each of the first power source and the second power source can be appropriately cooled.

First Embodiment

Ship Propulsion Machine

[0055] FIG. 1 illustrates a ship propulsion machine 1 according to the first embodiment of the present invention. The ship propulsion machine 1 is a device for propelling a boat. The ship propulsion machine 1 of the embodiment is an outboard motor, and is mounted on the boat. As illustrated in FIG. 1, the ship propulsion machine 1 includes a propeller 2, an engine (internal combustion engine) 4 as a first power source for rotating the propeller 2, a motor (electric motor) 6 as a second power source for rotating the propeller 2, and an inverter 8 that controls driving of the motor 6.

Power Transmission Mechanism

[0056] FIG. 2 illustrates a power transmission mechanism 11 of the ship propulsion machine 1. As illustrated in FIG. 2, the ship propulsion machine 1 includes the power transmission mechanism 11 that transmits 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 a crankshaft 5 of the engine 4 via a gear, and rotates upon receiving rotation of the crankshaft 5. The motor drive shaft 13 is connected to an output shaft 7 of the motor 6 and rotates integrally with the output shaft 7. The power switching mechanism 16 is a mechanism that switches whether to transmit rotation of the engine drive shaft 12 to the transmission shaft 15 or transmit rotation of the motor drive shaft 13 to the transmission shaft 15. The transmission shaft 15 is connected to an 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 rotation of the transmission shaft 15 to a propeller shaft 3. The rotation transmission mechanism 23 includes a first gear mechanism 24 that switches a rotation direction of the propeller shaft 3. The ship propulsion machine 1 of the embodiment employs contra-rotating propellers and includes two propellers 2 and two propeller shafts 3 to which the propellers 2 are respectively fixed. The rotation transmission mechanism 23 includes a second gear mechanism 25 that transmits the rotation of the transmission shaft 15 to the two propeller shafts 3 so that rotation directions of the propeller shafts 3 are opposite to each other.

Power Switching Mechanism

[0057] FIGS. 3A and 3B illustrate a detailed configuration of the power switching mechanism 16. In detail, FIG. 3A illustrates the power switching mechanism 16 when a dog clutch 19 is moved upward, and FIG. 3B illustrates the power switching mechanism 16 when the dog clutch 19 is moved downward.

[0058] As illustrated in FIG. 3A, the power switching mechanism 16 includes an engaging member 17, a clutch shaft 18, the 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 in a vertical direction, and a lower end of the engine drive shaft 12 and an upper end of the transmission shaft 15 face each other. The motor drive shaft 13 extends in a front-rear direction, and a front end of the motor drive shaft 13 faces a space between the lower end of the engine drive shaft 12 and the upper end of the transmission shaft 15. The engaging 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 engaging member 17. The dog clutch 19 is attached to an upper part of the clutch shaft 18 to not be rotatable relative to the clutch shaft 18 but to be movable up and down relative to the clutch shaft 18. The transmission gear 20 is disposed on an outer circumferential side of the upper part of the clutch shaft 18 and below the dog clutch 19. The transmission gear 20 is provided to be rotatable relative to the clutch shaft 18. That is, an insertion hole 20A is formed in a center of the transmission gear 20, and the upper part of the clutch shaft 18 is inserted into the insertion hole 20A. A diameter of the insertion hole 20A is larger than an outer diameter of the upper part of the clutch shaft 18, and an outer circumferential surface of the upper part of the clutch shaft 18 is not in contact with an inner circumferential surface of the insertion hole 20A. The transmission gear 20 is a bevel gear, and the transmission gear 20 meshes with a 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. The one-way clutch 21 is attached between a lower part of the clutch shaft 18 and a boss of the transmission gear 20.

[0059] The dog clutch 19 has a function of switching a connection mode of the engine drive shaft 12, the motor drive shaft 13, and the transmission shaft 15 between a mode in which the engine drive shaft 12 and the transmission shaft 15 are connected to each other and a mode in which the motor drive shaft 13 and the transmission shaft 15 are connected to each other. The one-way clutch 21 has a function of transmitting rotation of the transmission gear 20 to the transmission shaft 15 only when a rotation speed of the transmission gear 20 in a predetermined direction is higher than a rotation speed of the transmission shaft 15 in the predetermined direction. A 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 the operation of the power switching mechanism 16 are as follows.

[0060] As illustrated in FIG. 3A, when the dog clutch 19 moves upward, an engaging portion 19A formed in an upper part of the dog clutch 19 and an engaging portion 17A formed in the engaging 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 engaging member 17, the dog clutch 19, and the clutch shaft 18. As a result, the rotation of the engine drive shaft 12 is transmitted to the transmission shaft 15 via the dog clutch 19. When the dog clutch 19 moves upward, an engaging portion 19B formed in a lower part of the dog clutch 19 and an engaging portion 20B formed in the transmission gear 20 are separated from each other. As a result, 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. As a result, the rotation of the motor drive shaft 13 is no longer transmitted to the transmission shaft 15 via the dog clutch 19.

[0061] 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 predetermined direction is higher than the rotation speed of the transmission shaft 15 in the 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 when the rotation of the motor 6 is transmitted to the transmission gear 20, a rotation direction of the transmission gear 20 is the above-described predetermined direction. The above-described predetermined direction is a 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, and the like. When a rotation speed of the motor 6 increases, the rotation speed of the transmission gear 20 in the above-described predetermined direction accordingly increases. Then, when the rotation speed of the transmission gear 20 in the above-described predetermined direction increases than the rotation speed of the transmission shaft 15 in the above-described predetermined direction, the rotation of the motor drive shaft 13 is transmitted to the transmission shaft 15 via the one-way clutch 21.

[0062] As such, when the dog clutch 19 moves upward and the rotation speed of the transmission gear 20 in the above-described predetermined direction is higher than the rotation speed of the transmission shaft 15 in the above-described predetermined direction, 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. Meanwhile, when the dog clutch 19 moves upward and the rotation speed of the transmission gear 20 in the above-described predetermined direction is equal to or less than the rotation speed of the transmission shaft 15 in the above-described predetermined direction, only the rotation of the engine drive shaft 12 is transmitted to the transmission shaft 15 via the dog clutch 19.

[0063] Meanwhile, as illustrated in FIG. 3B, when the dog clutch 19 moves downward, the engaging portion 19A formed in the upper part of the dog clutch 19 and the engaging portion 17A formed in the engaging member 17 are separated from each other. As a result, connection between the engine drive shaft 12 and the transmission shaft 15 via the engaging 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. When the dog clutch 19 moves downward, the engaging portion 19B formed in the lower part of the dog clutch 19 and the engaging portion 20B formed in the transmission gear 20 engage 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. When the dog clutch 19 moves downward, the transmission gear 20 and the clutch shaft 18 rotate integrally via the dog clutch 19, so that the one-way clutch 21 attached between the transmission gear 20 and the clutch shaft 18 stops operation. As such, when the dog clutch 19 moves downward, only the rotation of the motor drive shaft 13 is transmitted to the transmission shaft 15 via the dog clutch 19.

[0064] For example, when the boat is operated at a low speed, the dog clutch 19 is moved downward so that only the rotation of the motor drive shaft 13 is transmitted to the transmission shaft 15 via the dog clutch 19. Then, the motor 6 is driven and the engine 4 enters 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. Accordingly, the boat can move smoothly even at a very low speed.

[0065] When the boat is operated at a high constant speed, 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 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. Accordingly, it is possible to reduce electricity consumption.

[0066] When accelerating the boat to glide, 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 to increase the rotation speed of each of the engine 4 and the motor 6. As a result, the power of the engine 4 is transmitted to the propeller shaft 3 via the dog clutch 19. When the rotation speed of the motor 6 increases, the rotation speed of the transmission gear 20 in the above-described predetermined direction increases than the rotation speed of the transmission shaft 15 in the above-described predetermined 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. Accordingly, the boat can accelerate quickly and smoothly.

Cooling Structure

[0067] FIG. 4 illustrates a cooling structure 31 of the ship propulsion machine 1. As illustrated in FIG. 4, the ship propulsion machine 1 includes a liquid-cooling cooling structure 31 that cools the engine 4, the motor 6, and the inverter 8. The cooling structure 31 includes an intake port 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.

[0068] The intake port 32 is a port that takes water (for example, seawater) outside the ship propulsion machine 1 into the ship propulsion machine 1 as cooling water. The intake port 32 is provided in a lower part of the ship propulsion machine 1 positioned below the water surface.

[0069] The first cooling water supply passage 33 connects the intake port 32 to the engine cooling mechanism 35, and is a passage through which the cooling water taken in from the intake port 32 flows toward the engine cooling mechanism 35. The first cooling water supply passage 33 is formed by a hole provided in the ship propulsion machine 1, a pipe or a hose attached around the engine 4, or the like.

[0070] The water pump 34 is a pump that sends cooling water flowed into the first cooling water supply passage 33 from outside of the ship propulsion machine 1 via the intake port 32 toward the engine cooling mechanism 35. The water pump 34 is provided inside the ship propulsion machine 1. The water pump 34 is connected midway of the first cooling water supply passage 33. As described below, a second cooling water supply passage 45 is branched from the first cooling water supply passage 33 at a branch point P located midway of the first cooling water supply passage 33. The water pump 34 is disposed between the intake port 32 and the branch point P. The water pump 34 is driven by the power of the engine 4 or the motor 6. For example, the water pump 34 is attached to a shaft of the power transmission mechanism 11, specifically, the transmission shaft 15 that is always rotated by the power of either the engine 4 or the motor 6 while the ship propulsion machine 1 is operated, and is driven by the rotation of the transmission shaft 15. The water pump 34 may be an electric pump. The electric pump includes a motor dedicated for driving the pump and is driven by the motor. The water pump 34 is a specific example of a pump.

[0071] 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 of cooling passages formed inside or around the engine 4. The engine 4 is cooled by the cooling water supplied via the first cooling water supply passage 33 flowing in the engine cooling mechanism 35.

[0072] The first cooling water discharge passage 36 connects the engine cooling mechanism 35 to the drain port 37, and is a passage through which the cooling water after flowing in the engine cooling mechanism 35 flows toward the drain port 37. The first cooling water discharge passage 36 is formed by a hole provided in the ship propulsion machine 1, a pipe or a hose attached around the engine 4, or the like.

[0073] The drain port 37 is a port that discharges the cooling water after flowing in the engine cooling mechanism 35 and the cooling water after flowing in a heat exchanger 43 to outside of the ship propulsion machine 1. The drain port 37 is provided at a lower rear part of the ship propulsion machine 1.

[0074] The cooling water temperature control valve 38 is a valve that controls a flow rate of the cooling water in the first cooling water supply passage 33 based on a temperature of the cooling water after flowing in the engine cooling mechanism 35. Specifically, 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 flowing in the engine cooling mechanism 35 increases. The cooling water temperature control valve 38 is connected, for example, to an outlet side portion of the engine cooling mechanism 35 or an inlet side portion of the first cooling water discharge passage 36. The cooling water temperature control valve 38 detects the temperature of the cooling water after flowing in the engine cooling mechanism 35, that is, the temperature of the cooling water after cooling the engine 4. The higher the detected cooling water temperature is, the larger a valve opening degree of the cooling water temperature control valve 38 is. The cooling water temperature control valve 38 is, for example, a thermostat. The cooling water temperature control valve 38 is a specific example of a flow rate control valve.

[0075] When an amount of heat generated by the engine 4 is large, the temperature of the cooling water after flowing in the engine cooling mechanism 35 rises. When the temperature of the cooling water after flowing in the engine cooling mechanism 35 is high, the valve opening degree of the cooling water temperature control valve 38 widens, and the flow rate of the cooling water flowing out of the engine cooling mechanism 35 to the first cooling water discharge passage 36 increases. 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 increase. By the flow rate of the cooling water in the engine cooling mechanism 35 increasing, a cooling capacity for the engine 4 by the engine cooling mechanism 35 increases. Meanwhile, when the amount of heat generated by the engine 4 is small, the temperature of the cooling water after flowing in the engine cooling mechanism 35 falls. When the temperature of the cooling water after flowing in the engine cooling mechanism 35 is low, the valve opening degree of the cooling water temperature control valve 38 narrows, and the flow rate of the cooling water flowing out from the engine cooling mechanism 35 to the first cooling water 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 decreases. As the flow rate of the cooling water in the engine cooling mechanism 35 decreases, the cooling capacity for the engine 4 by the engine cooling mechanism 35 decreases. As such, the cooling water temperature control valve 38 adjusts the cooling capacity for the engine by engine cooling mechanism 35 so that the cooling capacity corresponds to the amount of heat generated by the engine 4.

[0076] The cooling structure 31 includes a cooling medium circulation passage 39, a cooling medium pump 40, a motor cooling mechanism 41, an inverter cooling mechanism 42, the heat exchanger 43, and a degassing tank 44.

[0077] 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 ship propulsion machine 1. The cooling medium circulation passage 39 is formed by a hole provided in the ship propulsion machine 1, a pipe or a hose attached around the engine 4, or the like. The cooling medium is liquid, and for example, is a coolant liquid.

[0078] The cooling medium pump 40 is a pump that circulates the cooling medium. The cooling medium circulates in the cooling medium circulation passage 39 by driving the cooling medium pump 40. The cooling medium pump 40 is provided midway of the cooling medium circulation passage 39. The cooling medium pump 40 is, for example, an electric pump. The electric pump includes a motor dedicated for driving the pump and is driven by the motor.

[0079] The motor cooling mechanism 41 is provided in the motor 6. The motor cooling mechanism 41 is, for example, a cooling jacket, and is configured of a cooling passage formed inside or around the motor 6. The motor cooling mechanism 41 is connected to the cooling medium circulation passage 39. The cooling medium that circulates in the cooling medium circulation passage 39 flows in the motor cooling mechanism 41. The motor 6 is cooled by the cooling medium flowing in the motor cooling mechanism 41.

[0080] 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 of a cooling passage formed inside or around the inverter 8. The inverter cooling mechanism 42 is connected to the cooling medium circulation passage 39. The cooling medium that circulates in the cooling medium circulation passage 39 flows in the inverter cooling mechanism 42. The inverter 8 is cooled by the cooling medium flowing in the inverter cooling mechanism 42.

[0081] The heat exchanger 43 is a device that performs heat exchange between the cooling medium that circulates in the cooling medium circulation passage 39 and the cooling water taken in from the intake port 32, thereby cooling the cooling medium that circulates in the cooling medium circulation passage 39. The heat exchanger 43 is provided inside the ship propulsion machine 1 (see FIG. 1). The heat exchanger 43 includes 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 that circulates in the cooling medium circulation passage 39 flows in the cooling medium flow path. As described below, the cooling water flow path is connected to the first cooling water supply passage 33 via the second cooling water supply passage 45 branched from the first cooling water supply passage 33. As a result, a part of the cooling water taken in from the intake port 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 in the cooling water flow path. Heat exchange occurs between the cooling medium flowing in the cooling medium flow path and the cooling water flowing in the cooling water flow path.

[0082] The degassing tank 44 has a function of separating gas contained in the cooling medium that circulates in the cooling medium circulation passage 39 from the cooling medium, and is connected to the cooling medium circulation passage 39.

[0083] By driving the cooling medium pump 40, the cooling medium circulates in the cooling medium circulation passage 39, and meanwhile, the cooling medium sequentially flows in the motor cooling mechanism 41, the inverter cooling mechanism 42, and the cooling medium flow path of the heat exchanger 43. Accordingly, the motor 6 and the inverter 8 can be cooled. The cooling medium after cooling the motor 6 and the inverter 8 is cooled by the heat exchanger 43.

[0084] The cooling structure 31 includes the second cooling water supply passage 45, a second cooling water discharge passage 46, and a pressure valve 47.

[0085] The second cooling water supply passage 45 is a passage branched from the first cooling water supply passage 33 and connecting 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 the branch point P positioned midway of 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 ship propulsion machine 1, a pipe or a hose attached around the engine 4, or the like.

[0086] The second cooling water discharge passage 46 is a passage that connects the heat exchanger 43 to the drain port 37. The second cooling water discharge passage 46 connects the cooling water flow path of the heat exchanger 43 to the drain port 37, and flows the cooling water after flowing in the cooling water flow path of the heat exchanger 43 toward the drain port 37. The second cooling water discharge passage 46 is formed by a hole provided in the ship propulsion machine 1, a pipe or a hose attached around the engine 4, or the like. In the embodiment, the second cooling water discharge passage 46 is connected midway of the first cooling water discharge passage 36. The cooling water flowing in the second cooling water discharge passage 46 flows into the first cooling water discharge passage 36 at a junction point Q, merges with the cooling water flowing in the first cooling water discharge passage 36, and flows toward the drain port 37.

[0087] The pressure valve 47 is a valve that controls the inflow of the cooling water from the first cooling water supply passage 33 to the second cooling water supply passage 45. Specifically, the pressure valve 47 controls an amount of the cooling water flowing from the first cooling water supply passage 33 to the second cooling water supply passage 45 based on a pressure of the cooling water in the first cooling water supply passage 33. More specifically, the pressure valve 47 controls the amount of the cooling water flowing from the first cooling water supply passage 33 to the second cooling water supply passage 45 so that the higher the pressure of the cooling water in the first cooling water supply passage 33, the smaller the amount of the cooling water flowing from the first cooling water supply passage 33 to the second cooling water supply passage 45. The pressure valve 47 is connected, for example, to the branch point P between the first cooling water supply passage 33 and the second cooling water supply passage 45 or to an inlet side portion of the second cooling water 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.

[0088] In the cooling structure 31, the cooling water taken into the ship propulsion machine 1 from outside of the ship propulsion machine 1 via the intake port 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 degree of the pressure valve 47 narrows. Therefore, the cooling water flowing in the first cooling water supply passage 33 is less likely to flow into the second cooling water supply passage 45. Accordingly, in 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, a ratio of an amount of the cooling water supplied to the engine cooling mechanism 35 to an amount of the cooling water supplied to the heat exchanger 43 increases. As a result, the cooling capacity for the engine 4 by the engine cooling mechanism 35 increases. Meanwhile, when the pressure of the cooling water in the first cooling water supply passage 33 is low, the valve opening degree of the pressure valve 47 widens. Therefore, the cooling water flowing in the first cooling water supply passage 33 easily flows into the second cooling water supply passage 45. Accordingly, in 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, a ratio of the amount of the cooling water supplied to the heat exchanger 43 to the amount of the cooling water supplied to the engine cooling mechanism 35 increases. As a result, the cooling capacity for the cooling medium by the heat exchanger 43, that is, the cooling capacity for the motor 6 and the inverter 8 by the heat exchanger 43 increases.

Example of Boat Operation Mode and Cooling Structure Operation

[0089] For example, when the boat is operated at a low speed, the dog clutch 19 in the power switching mechanism 16 is moved downward so that only the rotation of the motor drive shaft 13 is transmitted to the transmission shaft 15 via the dog clutch 19. Then, the motor 6 is driven and the engine 4 enters an idling state. As a result, the transmission shaft 15 rotates by the power of the motor 6 and the water pump 34 is driven. By driving the water pump 34, the cooling water taken in from outside of the ship propulsion machine 1 via the intake port 32 sequentially flows in the first cooling water supply passage 33, the engine cooling mechanism 35, and the first cooling water discharge passage 36, and is then discharged to outside of the ship propulsion machine 1 from the drain port 37. Here, since the engine 4 is in the idling state, the amount of heat generated by the engine 4 is small. Therefore, the temperature of the cooling water after flowing in the engine cooling mechanism 35 is low. When the temperature of the cooling water after flowing in the engine cooling mechanism 35 is low, the valve opening degree of the cooling water temperature control valve 38 narrows. 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. By the valve opening degree of the pressure valve 47 increasing, the cooling water flowing in the first cooling water supply passage 33 easily flows into the second cooling water supply passage 45. Accordingly, in 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, a ratio of the amount of the cooling water supplied to the heat exchanger 43 to the amount of the cooling water supplied to the engine cooling mechanism 35 increases. The cooling water flowed from the first cooling water supply passage 33 into the second cooling water supply passage 45 sequentially flows in 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 to outside of the ship propulsion machine 1 from the drain port 37.

[0090] Meanwhile, when the boat is operated at a high constant 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. As a result, the transmission shaft 15 rotates by the power of the engine 4 and the water pump 34 is driven. By driving the water pump 34, the cooling water taken in from outside of the ship propulsion machine 1 via the intake port 32 flows in the first cooling water supply passage 33, the engine cooling mechanism 35, and the first cooling water discharge passage 36, and is then discharged to outside of the ship propulsion machine 1 from the drain port 37. Here, as the engine 4 is driven at a high speed, the amount of heat generated by the engine 4 is large. Therefore, the temperature of the cooling water after flowing in the engine cooling mechanism 35 is high. When the temperature of the cooling water after flowing in the engine cooling mechanism 35 is high, the valve opening degree of the cooling water temperature control valve 38 widens. As a result, the flow rate of the cooling water in the first cooling water supply passage 33 increases, the pressure of the cooling water in the first cooling water supply passage 33 increases, and the valve opening degree of the pressure valve 47 decreases. By the valve opening degree of the pressure valve 47 decreasing, the cooling water flowing in the first cooling water supply passage 33 is less likely to flow into the second cooling water supply passage 45. Accordingly, in 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, a ratio of an amount of the cooling water supplied to the engine cooling mechanism 35 to an amount of the cooling water supplied to the heat exchanger 43 increases. The cooling water flowed from the first cooling water supply passage 33 into the second cooling water supply passage 45 flows in 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 to outside of the ship propulsion machine 1 from the drain port 37.

[0091] Meanwhile, when accelerating the boat to glide, 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 and the motor 6 are driven to increase the rotation speed of each of the engine 4 and the motor 6. As a result, the transmission shaft 15 rotates by the power of the engine 4 and the motor 6, and the water pump 34 is driven. By driving the water pump 34, the cooling water taken in from outside of the ship propulsion machine 1 via the intake port 32 flows in the first cooling water supply passage 33, the engine cooling mechanism 35, and the first cooling water discharge passage 36, and is then discharged to outside of the ship propulsion machine 1 from the drain port 37. Here, as the rotation speed of the engine 4 increases, the amount of heat generated by the engine 4 increases. Therefore, the temperature of the cooling water after flowing in the engine cooling mechanism 35 rises. When the temperature of the cooling water after flowing in the engine cooling mechanism 35 is high, the valve opening degree of the cooling water temperature control valve 38 widens. As a result, the flow rate of the cooling water in the first cooling water supply passage 33 increases, the pressure of the cooling water in the first cooling water supply passage 33 increases, and the valve opening degree of the pressure valve 47 decreases. By the valve opening degree of the pressure valve 47 decreasing, the cooling water flowing in the first cooling water supply passage 33 is less likely to flow into the second cooling water supply passage 45. Accordingly, in 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, a ratio of an amount of the cooling water supplied to the engine cooling mechanism 35 to an amount of the cooling water supplied to the heat exchanger 43 increases. The cooling water flowed from the first cooling water supply passage 33 into the second cooling water supply passage 45 flows in 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 to outside of the ship propulsion machine 1 from the drain port 37.

[0092] As such, in the cooling structure 31, when the boat is operated at a low speed, that is, when the motor 6 is driven and the engine 4 is idling, a ratio of the amount of the cooling water supplied to the heat exchanger 43 to the amount of the cooling water supplied to the engine cooling mechanism 35 increases. As a result, the cooling capacity for the cooling medium by the heat exchanger 43 increases compared to the cooling capacity for the cooling medium by the heat exchanger 43 when the boat is operated at a constant high speed or is gliding. Simultaneously, the cooling capacity for the engine by the engine cooling mechanism 35 decreases compared to the cooling capacity for the engine by the engine cooling mechanism 35 when the boat is operated at a constant high speed or is gliding. When the motor 6 is driven while the boat is operated at a low speed, the motor 6 and the inverter 8 generate heat so that the temperature of the cooling medium rises. By increasing the amount of the cooling water supplied to the heat exchanger 43 to increase the cooling capacity for the cooling medium by the heat exchanger 43 when the boat is operated at a low speed, the temperature of the cooling medium can be quickly and reliably prevented from rising. Meanwhile, when the engine 4 is idling while the boat is operated at a low speed, the amount of heat generated by the engine 4 is small. By reducing the amount of the cooling water supplied to the engine cooling mechanism 35 to lower the cooling capacity for the engine 4 by the engine cooling mechanism 35 when the boat is operated at a low speed, over-cooling of the engine 4 can be avoided.

[0093] Meanwhile, in the cooling structure 31, when the boat is operated at a constant high speed, that is, when the engine 4 is operated at a high speed and the motor 6 is stopped, a ratio of the amount of the cooling water supplied to the engine cooling mechanism 35 to the amount of the cooling water supplied to the heat exchanger 43 increases. As a result, the cooling capacity for the engine by the engine cooling mechanism 35 increases compared to the cooling capacity for the engine by the engine cooling mechanism 35 when the boat is operated at a low speed. Simultaneously, the cooling capacity for the cooling medium by the heat exchanger 43 decreases compared to the cooling capacity for the cooling medium by the heat exchanger 43 when the boat is operated at a low speed. When the engine 4 is driven at a high speed while the boat is operated at a constant high speed, the amount of heat generated by the engine 4 increases. By increasing the amount of the cooling water supplied to the engine cooling mechanism 35 to increase the cooling capacity for the engine 4 by the engine cooling mechanism 35 when the boat is operated at a constant high speed, the engine 4 can be cooled quickly and reliably. Meanwhile, when the boat is operated at a constant high speed and the motor 6 is stopped, the motor 6 and the inverter 8 do not generate heat. Therefore, when the boat is operated at a constant high speed, there is no problem in reducing the amount of cooling water supplied to the heat exchanger 43 to lower the cooling capacity for the cooling medium by the heat exchanger 43.

[0094] Meanwhile, in the cooling structure 31, when the boat is gliding, that is, when the engine 4 and the motor 6 are driving and the rotation speeds of the engine 4 and the motor 6 are increasing, a ratio of the amount of the cooling water supplied to the engine cooling mechanism 35 to the amount of the cooling water supplied to the heat exchanger 43 increases, similar to when the boat is operated at a constant high speed. As a result, the cooling capacity for the engine by the engine cooling mechanism 35 increases compared to the cooling capacity for the engine by the engine cooling mechanism 35 when the boat is operated at a low speed. Simultaneously, the cooling capacity for the cooling medium by the heat exchanger 43 decreases compared to the cooling capacity for the cooling medium by the heat exchanger 43 when the boat is operated at a low speed. When the rotation speed of the engine 4 increases while the boat is gliding, the amount of heat generated by the engine 4 increases. By increasing the amount of the cooling water supplied to the engine cooling mechanism 35 to increase the cooling capacity of the engine 4 by the engine cooling mechanism 35 when the boat is gliding, the engine 4 can be cooled quickly and reliably. Meanwhile, when the rotation speed of the motor 6 increases while the boat is gliding, the motor 6 and the inverter 8 generate heat. However, duration of gliding of the boat when the boat is gliding is shorter than duration of a constant high-speed operation of the boat when the boat is operated at a constant high speed. Therefore, the amount of heat generated by the motor 6 and the inverter 8 when the boat is gliding is not so large. Therefore, even when the amount of the cooling water supplied to the heat exchanger 43 is reduced when the boat is gliding, the heat exchanger 43 can prevent the temperature of the cooling medium from rising and the motor 6 and the inverter 8 can be sufficiently cooled. For example, by adopting a heat exchanger with a large heat capacity as the heat exchanger 43, or by adopting a cooling medium with a large heat capacity as the cooling medium flowing in the cooling medium circulation passage 39, the motor 6 and the inverter 8 can be sufficiently cooled even when the amount of the cooling water supplied to the heat exchanger 43 is reduced when the boat is gliding.

[0095] As described above, in the ship propulsion machine 1 of the first embodiment of the present invention, the cooling water after flowing in the engine cooling mechanism 35 flows in the first cooling water discharge passage 36 and is then discharged to outside of the ship propulsion machine 1 from the drain port 37. Therefore, the cooling water after flowing in the engine cooling mechanism 35 does not flow in the cooling water flow path of the heat exchanger 43, and accordingly, the cooling water heated by flowing in the engine cooling mechanism 35 does not flow in the cooling water flow path of the heat exchanger 43. The cooling water after flowing in the cooling water flow path of the heat exchanger 43 flows in the second cooling water discharge passage 46, and is then discharged to outside of the ship propulsion machine 1 from the drain port 37. Therefore, the cooling water after flowing in the cooling water flow path of the heat exchanger 43 does not flow in the engine cooling mechanism 35, and accordingly, the cooling water heated by flowing in the cooling water flow path of the heat exchanger 43 does not flow in the engine cooling mechanism 35. Therefore, according to the ship propulsion machine 1 of the embodiment, it is easy to individually cool the engine 4 and the heat exchanger 43, and accordingly, each of the two power sources, that is, each of the engine 4 and the motor 6 can be appropriately cooled.

[0096] The ship propulsion machine 1 of the embodiment includes the 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 45, in which the pressure valve 47 can change the ratio between the amount of the cooling water supplied to the engine cooling mechanism 35 and the amount of the cooling water supplied to the heat exchanger 43. As such, according to the ship propulsion machine 1 of the embodiment, it is easy to individually set the amount of the cooling water supplied to the engine cooling mechanism 35 and the amount of the cooling water supplied to the heat exchanger 43, and accordingly, each of the two power sources, that is, each of the engine 4 and the motor 6 can be appropriately cooled.

[0097] In the ship propulsion machine 1 of the 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. The pressure valve 47 controls the amount of the cooling water flowing from the first cooling water supply passage 33 to the second cooling water supply passage 45 so that the higher the pressure of the cooling water in the first cooling water supply passage 33, the smaller the amount of the cooling water flowing from the first cooling water supply passage 33 to the second cooling water supply passage 45. As described above, when the engine 4 is driven at a high speed while the boat is operated at a constant high speed, the amount of heat generated by the engine 4 increases, and the temperature of the cooling water after cooling the engine 4 rises. When the temperature of the cooling water after cooling the engine 4 rises, the flow rate of the cooling water in the first cooling water supply passage 33 increases 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 increases. When the pressure of the cooling water in the first cooling water supply passage 33 increases, by control of the pressure valve 47, the cooling water is less likely to flow from the first cooling water supply passage 33 into the second cooling water supply passage 45, the ratio of the amount of the cooling water supplied to the engine cooling mechanism 35 to the amount of the cooling water supplied to the heat exchanger 43 increases, and the cooling capacity for the engine 4 by the engine cooling mechanism 35 increases. As such, when the boat is operated at a constant high speed, by cooperation of the cooling water temperature control valve 38 and the pressure valve 47, the cooling capacity for the engine 4 by the engine cooling mechanism 35 increases, and the engine 4 that generates a larger amount of heat due to a high-speed operation can be quickly and reliably cooled. As described above, when the engine 4 enters an idling state and the motor 6 is driven during a low-speed operation of the boat, the amount of heat generated by the engine 4 decreases, and the temperature of the cooling water after cooling the engine 4 falls. When the temperature of the cooling water after cooling the engine 4 falls, the flow rate of the cooling water in the first cooling water supply passage 33 decreases 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 decreases. When the pressure of the cooling water in the first cooling water supply passage 33 decreases, by control of the pressure valve 47, the cooling water easily flows from the first cooling water supply passage 33 to the second cooling water supply passage 45, the ratio of the amount of the cooling water supplied to the heat exchanger 43 to the amount of the cooling water supplied to the engine cooling mechanism 35 increases, and the cooling capacity for the cooling medium by the heat exchanger 43 increases. As such, when the boat is operated at a low speed, by cooperation of the cooling water temperature control valve 38 and the pressure valve 47, the cooling capacity for the cooling medium by the heat exchanger 43 increases, the cooling medium of which the temperature rose due to heat generated by the motor 6 and the inverter 8 can be quickly and reliably cooled, and the motor 6 can be quickly and reliably cooled by the cooling medium.

[0098] In the ship propulsion machine 1 of the embodiment, the motor cooling mechanism 41 and the inverter cooling mechanism 42 are connected to the cooling medium circulation passage 39, and the cooling medium flows in the motor cooling mechanism 41 and the inverter cooling mechanism 42. Accordingly, the cooling medium can quickly and reliably cool both of the motor 6 and the inverter 8.

Second Embodiment

[0099] FIG. 5 illustrates a cooling structure 61 in a ship propulsion machine 51 according to the second embodiment of the present invention. In the ship propulsion machine 51 according to the second embodiment of the present invention, similar components as those in the ship propulsion machine 1 according to the first embodiment of the present invention are given the same reference numerals, and description thereof will be omitted or simplified.

[0100] The cooling structure 31 in the ship propulsion machine 1 of the first embodiment of the present invention described above has a configuration in which, to cool the motor 6 and the inverter 8, the cooling medium circulates between the motor cooling mechanism 41 and the inverter cooling mechanism 42 and the heat exchanger 43, and the cooling water taken in from the intake port 32 is supplied to the heat exchanger 43 so that the cooling medium is cooled by the heat exchanger 43, thereby indirectly cooling the motor 6 and the inverter 8. In contrast, the cooling structure 61 in the ship propulsion machine 51 of the second embodiment of the present invention has a configuration in which, to cool the motor 6 and the inverter 8, the cooling water taken in from the intake port 32 is supplied to the motor cooling mechanism 41 and the inverter cooling mechanism 42, thereby directly cooling the motor 6 and the inverter 8.

[0101] As illustrated in FIG. 5, a second cooling water supply passage 62 in the cooling structure 61 is a passage branched from the first cooling water supply passage 33 and connecting the first cooling water supply passage 33 to the motor cooling mechanism 41. One end of the second cooling water supply passage 62 is connected to the branch point P positioned midway of 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 to each other by a third cooling water supply passage 63. A second cooling water discharge passage 64 is a passage that connects the inverter cooling mechanism 42 to 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 the junction point Q positioned midway of the first cooling water discharge passage 36. The pressure valve 47 that controls the inflow of the 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 an inlet side portion of the second cooling water supply passage 62.

[0102] In the cooling structure 61, when the water pump 34 is driven, the cooling water taken in from outside of the ship propulsion machine 51 via the intake port 32 sequentially flows in the first cooling water supply passage 33, the engine cooling mechanism 35, and the first cooling water discharge passage 36, and is then discharged to outside of the ship propulsion machine 51 from the drain port 37. A part of the cooling water taken in from outside of the ship propulsion machine 51 via the intake port 32 by driving the water pump 34 flows from the first cooling water supply passage 33 into the second cooling water supply passage 62, sequentially flows in 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 to outside of the ship propulsion machine 51 from the drain port 37.

[0103] In the ship propulsion machine 51 of the second embodiment of the present invention having such configuration, the cooling water heated by flowing in the engine cooling mechanism 35 does not flow in the motor cooling mechanism 41, and the cooling water heated by flowing in the motor cooling mechanism 41 does not flow in the engine cooling mechanism 35. Therefore, according to the ship propulsion machine 51 of the second embodiment, it is easy to individually cool the engine 4 and the motor 6, and accordingly, each of the two power sources, that is, each of the engine 4 and the motor 6 can be appropriately cooled.

[0104] In the ship propulsion machine 51 of the second embodiment, the ratio between the amount of the cooling water supplied to the engine cooling mechanism 35 and the amount of the cooling water supplied to the motor cooling mechanism 41 can be changed by the pressure valve 47. As such, according to the ship propulsion machine 51 of the second embodiment, it is easy to individually set the amount of the cooling water supplied to the engine cooling mechanism 35 and the amount of the cooling water supplied to the motor cooling mechanism 41, and accordingly, each of the two power sources, that is, each of the engine 4 and the motor 6 can be appropriately cooled.

[0105] According to the ship propulsion machine 51 of the second embodiment, similarly to the ship propulsion machine 1 of the first embodiment, by cooperation of the cooling water temperature control valve 38 and the pressure valve 47, the engine 4 that generates a larger amount of heat due to a high-speed operation while the boat is operated at a constant high speed can be quickly and reliably cooled, and the motor 6 and the inverter 8 that generated heat due to driving while the boat is operated at a low speed can also be quickly and reliably cooled.

[0106] In each of the above-described 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 thereto. The ship propulsion machine may include two motors for rotating the propeller, and one of the two motors may be used as the first power source and the other as the second power source.

[0107] In the present invention, the valve for controlling the inflow of the cooling water from the first cooling water supply passage to the second cooling water supply passage is not limited to the pressure valve.

[0108] In each of the above-described embodiments, an embodiment is 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 port 37, but two drain ports may be provided in the ship propulsion machine, in which the first cooling water discharge passage 36 is connected to one of the two drain ports and the second cooling water discharge passage 46 (64) is connected to the other of the two drain ports.

[0109] The present invention can also be applied to other types of ship propulsion machines that are not outboard motors.

[0110] The present invention can be modified as appropriate without departing from the spirit or the concept of the invention as can be read from the claims and the entire specification, and ship propulsion machines incorporating such modifications are also included in the technical concept of the present invention.