MARINE PROPULSION DEVICE

Abstract

A marine propulsion device for propelling a boat is provided The marine propulsion device includes a motor including an output shaft, a drive shaft configured to rotate upon receiving a rotation of the output shaft, a propeller shaft provided with a propeller and configured to be rotated upon receiving a rotation of the drive shaft, and a cooling device. The cooling device includes a cooling mechanism configured to cool the motor, and a water pump configured to send water outside the marine propulsion device to the cooling mechanism. An impeller of the water pump is connected via a one-way clutch to the output shaft, the drive shaft, or a rotation transmission member other than the drive shaft provided in the marine propulsion device and configured to rotate by the rotation of the output shaft.

Claims

1. A marine propulsion device for propelling a boat, the marine propulsion device comprising: a motor including an output shaft; a drive shaft configured to rotate upon receiving a rotation of the output shaft; a propeller shaft provided with a propeller and configured to be rotated upon receiving a rotation of the drive shaft; and a cooling device, wherein the cooling device includes a cooling mechanism configured to cool the motor, and a water pump configured to send water outside the marine propulsion device to the cooling mechanism, and an impeller of the water pump is connected via a one-way clutch to the output shaft, the drive shaft, or a rotation transmission member other than the drive shaft provided in the marine propulsion device and configured to rotate by the rotation of the output shaft.

2. The marine propulsion device according to claim 1, wherein the impeller is attached to a shaft, the shaft being attached to the output shaft, the drive shaft, or the rotation transmission member via the one-way clutch.

3. The marine propulsion device according to claim 1, wherein the impeller is attached to the output shaft, the drive shaft, or the rotation transmission member via the one-way clutch.

4. The marine propulsion device according to claim 1, wherein the motor is disposed so that an extension direction of the output shaft is a vertical direction, a transmission shaft disposed coaxially with the output shaft, below the output shaft, and extending in the vertical direction is connected to the output shaft via the one-way clutch, and the impeller is attached to the transmission shaft.

5. The marine propulsion device according to claim 1, wherein the motor is disposed so that an extension direction of the output shaft is a vertical direction, a gear configured to transmit the rotation of the output shaft to the drive shaft is attached to the output shaft, a transmission shaft disposed coaxially with the output shaft and extending downward from the gear is attached to the gear via the one-way clutch, and the impeller is attached to the transmission shaft.

6. The marine propulsion device according to claim 1, wherein a transmission shaft having a cylindrical shape and coaxial with the drive shaft is provided on an outer periphery of the drive shaft, the transmission shaft is attached to the outer periphery of the drive shaft via the one-way clutch, and the impeller is attached to the transmission shaft.

7. The marine propulsion device according to claim 1, wherein the impeller is made of rubber.

8. The marine propulsion device according to claim 1, wherein the cooling mechanism includes a heat exchanger configured to cool refrigerant by using water outside the marine propulsion device as cooling water, a motor cooling jacket provided in the motor and configured to cool the motor using the refrigerant, and a circulation passage configured to circulate the refrigerant between the heat exchanger and the motor cooling jacket.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0009] FIG. 1 is an explanatory diagram illustrating a marine propulsion device according to a first example of the present invention as viewed from the left.

[0010] FIG. 2 is an explanatory diagram illustrating the marine propulsion device according to the first example of the present invention as viewed from behind.

[0011] FIG. 3 is a cross-sectional view illustrating the marine propulsion device cut along a line A-A in FIG. 2 as viewed from the left.

[0012] FIG. 4 is a block diagram illustrating a configuration of a cooling device in the marine propulsion device according to the first example of the present invention.

[0013] FIG. 5 is an enlarged cross-sectional view illustrating a portion of the marine propulsion device in FIG. 3 including a water pump.

[0014] FIG. 6 is a cross-sectional view illustrating a marine propulsion device according to a second example of the present invention cut along at a position of the line A-A in FIG. 2 as viewed from the left.

[0015] FIG. 7 is an enlarged cross-sectional view illustrating a portion of the marine propulsion device in FIG. 6 including a water pump.

[0016] FIGS. 8A to 8C are explanatory diagrams illustrating another example of a connection configuration of a water pump according to the present invention.

DETAILED DESCRIPTION OF EXEMPLIFIED EMBODIMENTS

[0017] Recently, progress has been made in development of marine propulsion devices that use a motor (electric motor) as a power source for rotating a propeller.

[0018] In an engine, it is difficult to reverse a rotation direction of a crankshaft. Therefore, in a marine propulsion device, when a power source for rotating a propeller is an engine, generally, it is necessary to provide a shift mechanism as described above in the marine propulsion device to enable a boat to switch between forward and reverse movement.

[0019] In contrast, a motor can switch a rotation direction of a rotor through electrical control. Therefore, in a marine propulsion device, when a motor is used as a power source for rotating a propeller, a rotation direction of an output shaft of the motor can be switched by electrical control, thereby switching a rotation direction of each of a drive shaft and a propeller shaft so that a rotation direction of the propeller can be switched. Therefore, when a motor is used as a power source for rotating a propeller in a marine propulsion device, there is no need to provide a shift mechanism in the marine propulsion device. By not providing a shift mechanism in the marine propulsion device, a structure of the marine propulsion device can be simplified, the marine propulsion device can be miniaturized, and manufacturing costs of the marine propulsion device can be reduced.

[0020] However, in a marine propulsion device, when a motor is used as a power source for rotating a propeller and a rotation direction of an output shaft of the motor is switched by electrical control, the following problems arise.

[0021] In a rotary variable displacement water pump including a rubber impeller used as a water pump in many marine propulsion devices of the related art, a lifespan of the impeller is significantly shortened when a rotation direction of the impeller changes. When a motor is used as a power source for rotating a propeller and a rotation direction of an output shaft of the motor is switched by electrical control, a rotation direction of a drive shaft is reversed by reversing the rotation direction of the output shaft of the motor. Accordingly, a rotation direction of an impeller fixed to the drive shaft is changed. As a result, a lifespan of the impeller is significantly shortened.

[0022] The present invention is made considering, for example, the problems described above, and an object of the present invention is to provide a marine propulsion device that can prevent a lifespan of an impeller of a water pump from being shortened even when a motor is used as a power source for rotating a propeller and a rotation direction of an output shaft of the motor is switched.

[0023] A marine propulsion device according to an embodiment of the present invention includes a motor including an output shaft, a drive shaft that rotates upon receiving rotation of the output shaft, a propeller shaft provided with a propeller and rotated upon receiving rotation of the drive shaft, and a cooling device. The cooling device for the marine propulsion device of the embodiment includes a cooling mechanism that cools the motor, and a water pump that sends water outside the marine propulsion device to the cooling mechanism. An impeller of the water pump is connected via a one-way clutch to the output shaft, the drive shaft, or a rotation transmission member other than the drive shaft provided in the marine propulsion device and configured to rotate by the rotation of the output shaft.

[0024] Here, for convenience of description, the output shaft, the drive shaft, and the rotation transmission member are each referred to as a "rotating body". Rotation of a rotor of the motor in one direction, and rotation of the rotating body when the rotor of the motor is rotated in the one direction are each referred to as "forward rotation". Rotation of the rotor of the motor in the other direction, and rotation of the rotating body when the rotor of the motor is rotated in the other direction are each referred to as "reverse rotation".

[0025] In the marine propulsion device of the embodiment, the impeller of the water pump is connected to any one rotating body via a one-way clutch. A one-way clutch is a clutch that transmits rotation only in a certain direction.

[0026] For example, when the rotor of the motor rotates forward by electrical control so that the rotating body to which the impeller is connected via the one-way clutch rotates forward, rotation of the rotating body is transmitted to the impeller via the one-way clutch, thereby rotating the impeller. Meanwhile, when the rotor of the motor rotates reversely by electrical control so that the rotating body to which the impeller is connected via the one-way clutch rotates reversely, rotation of the rotating body is not transmitted to the impeller via the one-way clutch, thereby not rotating the impeller.

[0027] By connecting the impeller of the water pump to any rotating body of the above-described rotating bodies via the one-way clutch, it is possible to prevent a rotation direction of the impeller of the water pump from changing by switching a rotation direction of the output shaft of the motor. Therefore, a lifespan of the impeller can be prevented from being shortened.

[0028] Since the lifespan of the impeller can be prevented from being shortened, a miniaturized, simple-structured, or inexpensive marine propulsion device that does not include a shift mechanism can be realized even when employing a water pump similar to that used in marine propulsion devices of the related art (for example, a rotary variable displacement water pump including a rubber impeller).

First Example

[0029] Some examples of the present invention will be described with reference to the drawings. In the description of each example, directions of up (Ud), down (Dd), front (Fd), back (Bd), left (Ld), and right (Rd) follow arrows drawn at the lower left of FIGS. 1 to 3 and 5 to 7.

Marine Propulsion Device

[0030] FIG. 1 illustrates a marine propulsion device 1 according to a first example of the present invention as viewed from the left. FIG. 2 illustrates the marine propulsion device 1 as viewed from behind. FIG. 3 illustrates a cross section of the marine propulsion device 1 cut along a line A-A in FIG. 2 as viewed from the left.

[0031] The marine propulsion device 1 is a device for propelling a boat. As illustrated in FIG. 1, a marine propulsion device 1 of the example is an outboard motor, and is mounted on the boat. The marine propulsion device 1 of the example is an electric outboard motor that uses a motor 3 as a power source for rotating a propeller 19.

[0032] As illustrated in FIG. 3, the marine propulsion device 1 includes the motor 3, an inverter 6, a speed reducer 11, a drive shaft 14, a propeller shaft 18, the propeller 19, and a rotation transmission mechanism 15.

[0033] The motor 3 is a power source for rotating the propeller 19. The motor 3 is, for example, an AC motor, and includes an output shaft 4, a rotor, a stator, and a motor case 5. The output shaft 4 excluding an end that outputs rotation of the rotor, the rotor, and the stator are accommodated in the motor case 5. The motor 3 is disposed in an upper part of the marine propulsion device 1. When the marine propulsion device 1 is mounted on the boat, the motor 3 is positioned above the water surface. The motor 3 is disposed in the marine propulsion device 1 so that an extension direction of the output shaft 4 is a vertical direction.

[0034] The inverter 6 is a device that controls driving of the motor 3. As illustrated in FIG. 3, the inverter 6 includes an inverter body 7 in which a circuit that controls driving of the motor 3 and the like are provided, and an inverter case 8 in which the inverter body 7 is accommodated. The inverter 6 is disposed above the motor 3. The inverter 6 is mounted on the motor 3 via an inverter mounting member 10.

[0035] The speed reducer 11 is a device that reduces rotation of the output shaft 4 of the motor 3 and transmits the rotation to the drive shaft 14. The speed reducer 11 is disposed below the motor 3. The speed reducer 11 includes a drive gear 12 and a driven gear 13. The drive gear 12 is coupled to a lower end of the output shaft 4 of the motor 3 and rotates integrally with the output shaft 4. The driven gear 13 is disposed in front of the drive gear 12, is coupled to an upper end of the drive shaft 14, and meshes with the drive gear 12. The drive gear 12 is a specific example of a "gear". The drive gear 12 is a specific example of a "rotation transmission member".

[0036] The drive shaft 14 is positioned in front of the output shaft 4 of the motor 3, and extends in the vertical direction from the speed reducer 11 to the rotation transmission mechanism 15. The drive shaft 14 rotates upon receiving rotation of the output shaft 4 transmitted via the speed reducer 11. Specifically, as described above, the driven gear 13 is coupled to the upper end of the drive shaft 14 and the drive shaft 14 rotates integrally with the driven gear 13.

[0037] The rotation transmission mechanism 15 is a mechanism that transmits rotation of the drive shaft 14 to the propeller shaft 18. The rotation transmission mechanism 15 includes two bevel gears 16 and 17 that mesh with each other. One bevel gear 16 is coupled to a lower end of the drive shaft 14 and rotates integrally with the drive shaft 14. The other bevel gear 17 is coupled to a front end of the propeller shaft 18.

[0038] The propeller shaft 18 extends in a front-rear direction and is disposed below the motor 3. The propeller shaft 18 rotates upon receiving rotation of the drive shaft 14 transmitted via the rotation transmission mechanism 15. Specifically, as described above, the bevel gear 17 of the rotation transmission mechanism 15 is coupled to the front end of the propeller shaft 18 and the propeller shaft 18 rotates integrally with the bevel gear 17. The propeller 19 is coupled to a rear part of the propeller shaft 18 and rotates integrally with the propeller shaft 18. The propeller shaft 18 and the propeller 19 are disposed in a lower part of the marine propulsion device 1 and are positioned below the water surface when the marine propulsion device 1 is mounted on the boat.

[0039] By controlling the inverter 6, the motor 3 is driven and the output shaft 4 rotates. Rotation of the output shaft 4 is transmitted to the drive shaft 14 while being reduced by the speed reducer 11, thereby rotating the drive shaft 14. Rotation of the drive shaft 14 is transmitted to the propeller shaft 18 by the rotation transmission mechanism 15, thereby rotating the propeller shaft 18 and the propeller 19. Rotation of the propeller 19 generates thrust for the boat.

[0040] As illustrated in FIG. 3, the marine propulsion device 1 includes a middle case 25 that accommodates the speed reducer 11 and an upper part of the drive shaft 14. The middle case 25 is disposed below the motor 3 and attached to the motor 3. The marine propulsion device 1 includes a lower case 27 that accommodates a lower part of the drive shaft 14, a front part of the propeller shaft 18, and the rotation transmission mechanism 15. The lower case 27 is disposed below the middle case 25 and attached to the middle case 25. An anti-cavitation plate 28 is provided in the lower case 27.

[0041] As illustrated in FIG. 1, the marine propulsion device 1 includes a mounting mechanism 30 for mounting the marine propulsion device 1 on the boat. The mounting mechanism 30 includes a clamp bracket 31 that fixes the marine propulsion device 1 to a transom of the boat, a swivel bracket 33 connected to the clamp bracket 31 via a tilt shaft 32, a pilot shaft 34 that extends in the vertical direction and is supported by the swivel bracket 33 to be rotatable, and mounts 35 and 36 that connect both upper and lower ends of the pilot shaft 34 to the marine propulsion device 1.

Cooling Device

[0042] The marine propulsion device 1 includes a liquid-cooling cooling device 41 that cools equipment requiring cooling provided in the marine propulsion device 1. The equipment requiring cooling provided in the marine propulsion device 1 is specifically the motor 3 and the inverter 6.

[0043] FIG. 4 illustrates a configuration of the cooling device 41. As illustrated in FIG. 4, the cooling device 41 includes an intake port 42, a supply passage, a water pump 51, a cooling mechanism 61, a discharge passage 55, a discharge chamber 57, and a drain port 58. The supply passage includes a lower internal supply passage 44, an upper internal supply passage 45, and an external supply passage 46.

[0044] The intake port 42 is a port that takes water from outside the marine propulsion device 1 into the marine propulsion device 1. The intake port 42 is provided in a portion of the marine propulsion device 1 submerged in water. Specifically, the intake port 42 is provided in a front part of a lower part of the lower case 27 as illustrated in FIGS. 1 and 3.

[0045] The supply passage is a passage that connects the intake port 42 to a heat exchanger 62 configuring a portion of the cooling mechanism 61, and is a passage that supplies water outside the marine propulsion device 1 taken into the marine propulsion device 1 from the intake port 42 to the heat exchanger 62 as cooling water. Thick arrows in FIG. 3 indicate a flow direction of cooling water in the supply passage. The supply passage includes the lower internal supply passage 44, the upper internal supply passage 45, and the external supply passage 46 as described above.

[0046] The water pump 51 is provided in midway of the supply passage. A portion of the supply passage from the intake port 42 to a suction port 54A (see FIG. 5) of the water pump 51 is the lower internal supply passage 44. The lower internal supply passage 44 is formed of, for example, a hole provided in the lower case 27 and a hole provided in the middle case 25. The supply passage passes a connection port 47 that opens on a rear surface of the middle case 25. A portion of the supply passage from a discharge port 54B (see FIG. 5) of the water pump 51 to the connection port 47 is the upper internal supply passage 45. The upper internal supply passage 45 is formed of, for example, a hole provided in the middle case 25. A portion of the supply passage from the connection port 47 to the heat exchanger 62 is the external supply passage 46. The external supply passage 46 is formed of, for example, a hose or a pipe. An outlet side end of the external supply passage 46 is connected to an inlet port of an internal cooling water flow path of the heat exchanger 62.

[0047] The water pump 51 is a pump that sends water outside the marine propulsion device 1, that is, cooling water, to the heat exchanger 62 via the supply passage. The water pump 51 is a rotary variable displacement water pump including a rubber impeller. The water pump 51 includes an impeller 52 and a pump case 54 that accommodates the impeller 52. As illustrated in FIG. 3, the water pump 51 is disposed in a lower part in the middle case 25. The water pump 51 is disposed below the motor 3 and the water pump 51 overlaps with the motor 3 when the marine propulsion device 1 is viewed from above. The water pump 51 is disposed so that a rotation axis of the impeller 52 is coaxial with the output shaft 4 of the motor 3. The pump case 54 is attached to a bottom part of the middle case 25. The pump case 54 may be attached to an upper surface of the lower case 27. As will be described in detail below, the impeller 52 of the water pump 51 is connected to the output shaft 4 of the motor 3 via the drive gear 12 of the speed reducer 11, a one-way clutch 84, and a transmission shaft 81. When the output shaft 4 of the motor 3 rotates in a direction that moves the boat forward, rotation of the output shaft 4 is transmitted to the impeller 52, thereby rotating the impeller 52.

[0048] The cooling mechanism 61 is a mechanism that cools the equipment requiring cooling provided in the marine propulsion device 1, that is, the motor 3 and the inverter 6. The cooling mechanism 61 cools refrigerant using the cooling water in the heat exchanger 62 and causes the refrigerant to flow in a motor cooling jacket 63 and an inverter cooling jacket 64, thereby cooling the motor 3 and the inverter 6. The cooling mechanism 61 will be described in detail below.

[0049] The discharge passage 55 is a passage that carries the cooling water after flowing in the internal cooling water flow path of the heat exchanger 62 to the drain port 58. As illustrated in FIGS. 1 and 2, the discharge passage 55 is formed of, for example, a hose or a pipe. An inlet side end of the discharge passage 55 is connected to an outlet port of the internal cooling water flow path provided in a lower part of the heat exchanger 62. As illustrated in FIG. 3, the discharge chamber 57 is provided from a rear part of the lower part in the middle case 25 to a rear part in the lower case 27, and as illustrated in FIG. 1, a connection port 56 that communicates with inside of the discharge chamber 57 opens on a left surface of the middle case 25. An outlet side end of the discharge passage 55 is connected to the connection port 56 and communicates with inside of the discharge chamber 57 via the connection port 56.

[0050] The drain port 58 is an opening that discharges the cooling water after flowing in the heat exchanger 62 to outside of the marine propulsion device 1. As illustrated in FIG. 3, the drain port 58 is formed in, for example, a hub of the propeller 19. The drain port 58 communicates with inside of the discharge chamber 57.

[0051] In FIG. 3, when the motor 3 is driven and the output shaft 4 of the motor 3 rotates in the direction that moves the boat forward, the impeller 52 of the water pump 51 rotates. As a result, water outside the marine propulsion device 1 taken into the marine propulsion device 1 from the intake port 42 sequentially flows in the lower internal supply passage 44, the water pump 51, the upper internal supply passage 45, and the external supply passage 46 as cooling water, then flows into the internal cooling water flow path of the heat exchanger 62, and flows in the internal cooling water flow path. The cooling water flows in the internal cooling water flow path of the heat exchanger 62, thereby cooling the refrigerant circulating in a circulation passage of the cooling mechanism 61. The cooling water after flowing in the internal cooling water flow path of the heat exchanger 62 flows in the discharge passage 55 (see FIG. 1), then in the discharge chamber 57 (see FIG. 3), and then is discharged to outside of the marine propulsion device 1 from the drain port 58.

Cooling Mechanism

[0052] As illustrated in FIG. 4, the cooling mechanism 61 includes the heat exchanger 62, the motor cooling jacket 63, the inverter cooling jacket 64, the circulation passage, a refrigerant pump 65, and a degassing tank 66. The circulation passage includes refrigerant passages 71 to 76.

[0053] The heat exchanger 62 is a device that cools the refrigerant by performing heat exchange between water outside the marine propulsion device 1, that is, cooling water, and the refrigerant circulating in the circulation passage. The refrigerant is, for example, a coolant such as LLC. In the heat exchanger 62, the internal cooling water flow path in which the cooling water flows and an internal refrigerant flow path in which the refrigerant flows are provided. The internal cooling water flow path and the internal refrigerant flow path are disposed to enable heat exchange between the cooling water flowing in the internal cooling water flow path and the refrigerant flowing in the internal refrigerant flow path. As illustrated in FIG. 1, the heat exchanger 62 is disposed behind the motor 3.

[0054] The motor cooling jacket 63 is a mechanism that cools the motor 3 using the refrigerant cooled by the heat exchanger 62. The motor cooling jacket 63 is provided in the motor 3 as illustrated in FIG. 3. For example, the motor cooling jacket 63 is configured of a flow path formed in the motor case 5 of the motor 3. The flow path configuring the motor cooling jacket 63 is formed over a wide area of the motor case 5. For example, the flow path is formed around an entire circumference of the motor case 5 and from one end to the other end of the motor case 5 in an axial direction.

[0055] The inverter cooling jacket 64 is a mechanism that cools the inverter 6 using the refrigerant cooled by the heat exchanger 62. The inverter cooling jacket 64 is provided in the inverter 6. For example, the inverter cooling jacket 64 is disposed in a lower part of a rear part of the inverter 6 and is positioned below a rear part of the inverter body 7. Specifically, the inverter cooling jacket 64 is configured of a flow path formed in a lower part of a rear part of the inverter case 8. The flow path extends from a left end to a right end of the inverter case 8.

[0056] The refrigerant pump 65 is a pump that circulates the refrigerant in the circulation passage. The refrigerant pump 65 is an electric pump, and is driven by, for example, a dedicated motor for the refrigerant pump 65 different from the motor 3. As illustrated in FIG. 1, the refrigerant pump 65 is disposed above the heat exchanger 62. The refrigerant pump 65 is disposed behind the inverter 6. The refrigerant pump 65 is mounted on the rear part of the inverter 6.

[0057] The degassing tank 66 has a function of releasing air bubbles generated in the refrigerant due to heat or the like, and a function as a reserve tank to absorb any increase or decrease in the amount of the refrigerant due to thermal expansion or aging of the refrigerant. The degassing tank 66 is disposed above the inverter 6 and mounted on the inverter 6.

[0058] The circulation passage is a passage that circulates the refrigerant between the heat exchanger 62, the motor cooling jacket 63, and the inverter cooling jacket 64. As illustrated in FIG. 4, the circulation passage connects between the equipment so that the refrigerant sequentially flows in the heat exchanger 62, the motor cooling jacket 63, the inverter cooling jacket 64, and the refrigerant pump 65, and then returns to the heat exchanger 62. The circulation passage includes the refrigerant passage 71 connecting the heat exchanger 62 to the motor cooling jacket 63, the refrigerant passage 72 connecting the motor cooling jacket 63 to the inverter cooling jacket 64, the refrigerant passage 73 connecting the inverter cooling jacket 64 to a passage connection portion 77, the refrigerant passage 74 connecting the passage connection portion 77 to the refrigerant pump 65, the refrigerant passage 75 connecting the refrigerant pump 65 to the heat exchanger 62, and the refrigerant passage 76 connecting the passage connection portion 77 to the degassing tank 66.

[0059] As illustrated in FIGS. 1 and 2, the refrigerant passage 71 extends from a left side of an upper part of the heat exchanger 62 to a rear side of a lower part of the motor 3. The refrigerant passage 71 is formed of, for example, a hose or a pipe. An inlet side end of the refrigerant passage 71 is connected to an outlet port of the internal refrigerant flow path that opens on a left surface of the upper part of the heat exchanger 62. An outlet side end of the refrigerant passage 71 is connected to an inlet port 63A (see FIG. 3) of the motor cooling jacket 63 that opens at a rear part of a lower part of the motor case 5.

[0060] As illustrated in FIG. 1, the refrigerant passage 72 is provided in a portion extending from an upper rear left part of the motor case 5 to a lower rear left part of the inverter case 8. The refrigerant passage 72 is formed of a hole provided in the portion and extending in the vertical direction. An inlet side end of the refrigerant passage 72 is connected to an outlet port of the motor cooling jacket 63 provided in the upper rear left part of the motor case 5, and an outlet side end of the refrigerant passage 72 is connected to an inlet port of the inverter cooling jacket 64 provided in the lower rear left part of the inverter case 8.

[0061] As illustrated in FIG. 2, the refrigerant passage 73 is disposed on the right rear of the inverter 6. The refrigerant passage 73 is formed of, for example, a hose or a pipe. An inlet side end of the refrigerant passage 73 is connected to an outlet port of the inverter cooling jacket 64 that opens on a right surface of the lower part of the rear part of the inverter case 8. An outlet side end of the refrigerant passage 73 is connected to the passage connection portion 77. The passage connection portion 77 connects between the outlet side end of the refrigerant passage 73, an inlet side end of the refrigerant passage 74, and a lower end of the refrigerant passage 76, and is formed of, for example, a T-shaped joint.

[0062] The refrigerant passage 74 is disposed on the right of the refrigerant pump 65. The refrigerant passage 74 is formed of, for example, a pipe. The inlet side end of the refrigerant passage 74 is connected to the passage connection portion 77. An outlet side end of the refrigerant passage 74 is connected to a suction port of the refrigerant pump 65 provided on a right surface of the refrigerant pump 65.

[0063] The refrigerant passage 75 extends from a lower side of a right part of the refrigerant pump 65 to a right side of the lower part of the heat exchanger 62. The refrigerant passage 75 is formed of, for example, a hose or a pipe. An inlet side end of the refrigerant passage 75 is connected to a discharge port of the refrigerant pump 65 provided in a lower right part of the refrigerant pump 65. An outlet side end of the refrigerant passage 75 is connected to an inlet port of the internal refrigerant flow path that opens on a right surface of the lower part of the heat exchanger 62.

[0064] The refrigerant passage 76 is disposed above a rear right part of the inverter 6 and behind a right part of the degassing tank 66. The refrigerant passage 76 is formed of, for example, a hose or a pipe. The lower end of the refrigerant passage 76 is connected to the passage connection portion 77. An upper end of the refrigerant passage 76 is connected to a rear right part of the degassing tank 66.

[0065] When the refrigerant pump 65 is driven, the refrigerant cooled by the heat exchanger 62 flows out from an outlet port of the internal refrigerant flow path of the heat exchanger 62, flows in the refrigerant passage 71, and then flows in the motor cooling jacket 63. The motor 3 is cooled by the refrigerant flowing in the motor cooling jacket 63. The refrigerant after flowing in the motor cooling jacket 63 flows in the refrigerant passage 72 and then flows in the inverter cooling jacket 64. The inverter body 7 is cooled by the refrigerant flowing in the inverter cooling jacket 64. The refrigerant after flowing in the inverter cooling jacket 64 sequentially flows in the refrigerant passage 73, the passage connection portion 77, the refrigerant passage 74, the refrigerant pump 65, and the refrigerant passage 75, and flows into the internal refrigerant flow path of the heat exchanger 62 from the inlet port of the internal refrigerant flow path of the heat exchanger 62. The refrigerant of which the temperature rose due to heat of the motor 3 and the inverter 6 is cooled in the heat exchanger 62 by cooling water taken in from outside the marine propulsion device 1.

[0066] The refrigerant is stored in the degassing tank 66. The air bubbles in the refrigerant move into the degassing tank 66 via the refrigerant passage 76 and are released to the atmosphere, for example, via a gas vent passage formed in the degassing tank 66. When the amount of the refrigerant flowing in the circulation passage is small, a cap of the degassing tank 66 is removed and the refrigerant is injected into the degassing tank 66 so that the refrigerant can be replenished.

Connection Structure of Water Pump

[0067] FIG. 5 illustrates an enlarged view of a portion of the marine propulsion device 1 in FIG. 3 including the water pump 51. As illustrated in FIG. 5, the impeller 52 of the water pump 51 is connected to the output shaft 4 of the motor 3 via the drive gear 12 of the speed reducer 11, the one-way clutch 84, and the transmission shaft 81.

[0068] The drive gear 12 includes a tooth portion 12A, an upper boss portion 12B, and a lower boss portion 12C. The drive gear 12 is attached to the lower end of the output shaft 4 of the motor 3. Specifically, the upper boss portion 12B of the drive gear 12 is coupled to the lower end of the output shaft 4 of the motor 3 via a spline. An outer periphery of the lower boss portion 12C of the drive gear 12 is supported to be rotatable by a portion of the middle case 25 via a bearing 85. An outer diameter of the lower boss portion 12C is larger than an outer diameter of the upper boss portion 12B, and an inner diameter of the lower boss portion 12C is larger than an inner diameter of the upper boss portion 12B.

[0069] The marine propulsion device 1 includes the transmission shaft 81. The transmission shaft 81 extends in the vertical direction and is disposed coaxially with the output shaft 4 of the motor 3. The transmission shaft 81 includes an upper shaft portion 82 and a lower shaft portion 83. An upper end of the lower shaft portion 83 is coupled to, for example, a lower end of the upper shaft portion 82 via a spline so that the upper shaft portion 82 and the lower shaft portion 83 rotate integrally. Therefore, the transmission shaft 81 can be regarded as a single shaft formed by coupling the upper shaft portion 82 to the lower shaft portion 83 to not be rotatable.

[0070] The transmission shaft 81 is attached to the drive gear 12 and extends downward from the drive gear 12. Specifically, an upper end of the transmission shaft 81 is inserted into the lower boss portion 12C of the drive gear 12. The upper end of the transmission shaft 81 is coupled to the lower boss portion 12C by a bearing 86 provided between the upper end of the transmission shaft 81 and the lower boss portion 12C to be rotatable relative to the lower boss portion 12C. The transmission shaft 81 is supported to be rotatable by a portion of the middle case 25 via a bearing 87 and a bearing 88.

[0071] The transmission shaft 81 is attached to the drive gear 12 via the one-way clutch 84. Specifically, the one-way clutch 84 is provided between the upper end of the transmission shaft 81 and the lower boss portion 12C, and the upper end of the transmission shaft 81 is coupled to the lower boss portion 12C via the one-way clutch 84. The one-way clutch 84 is a clutch that transmits rotation only in a certain direction. In the example, the one-way clutch 84 is configured so that rotation of the output shaft 4 of the motor 3 is transmitted to the transmission shaft 81 via the drive gear 12 only when the output shaft 4 rotates in a direction that rotates the propeller 19 forward. In other words, when the output shaft 4 of the motor 3 rotates in a direction that rotates the propeller 19 forward, the one-way clutch 84 transmits rotation of the output shaft 4 to the transmission shaft 81, and when the output shaft 4 of the motor 3 rotates in a direction that rotates the propeller 19 reversely, the one-way clutch 84 does not transmit rotation of the output shaft 4 to the transmission shaft 81. The propeller 19 rotates forward to generate thrust for moving the boat forward. The one-way clutch 84 transmits rotation of the output shaft 4 of the motor 3 to the transmission shaft 81 only when the output shaft 4 rotates in the direction that moves the boat forward.

[0072] The impeller 52 of the water pump 51 is attached to an outer periphery of the transmission shaft 81. Specifically, a lower end of the transmission shaft 81 is inserted into an insertion hole 53A of a shaft portion 53 provided in a center of the impeller 52. The impeller 52 is coupled to the lower end of the transmission shaft 81, for example, via a key or a spline to not be rotatable relative to the transmission shaft 81. Therefore, the impeller 52 rotates integrally with the transmission shaft 81. As described above, rotation of the output shaft 4 is transmitted to the transmission shaft 81 and the transmission shaft 81 rotates only when the output shaft 4 of the motor 3 rotates in the direction that moves the boat forward by operating the one-way clutch 84. Therefore, the impeller 52 rotates only when the output shaft 4 of the motor 3 rotates in the direction that moves the boat forward.

[0073] As such, the impeller 52 of the water pump 51 is connected to the output shaft 4 of the motor 3 via the one-way clutch 84 and rotates only when the output shaft 4 of the motor 3 rotates in the direction that moves the boat forward. Therefore, when the boat is moving forward, water outside the marine propulsion device 1, that is, cooling water, is sent to the heat exchanger 62 by the water pump 51, and in the heat exchanger 62, the cooling water cools the refrigerant circulating in the circulation passage of the cooling mechanism 61. Meanwhile, when the boat is moving rearward, the cooling water is not sent to the heat exchanger 62 by the water pump 51, and therefore the refrigerant is not cooled in the heat exchanger 62. However, a boat moves rearward for a very short time, such as when docking. As long as rearward movement is very short, heat generated from the motor 3 and the inverter 6 when the boat is moving rearward can be sufficiently absorbed by heat capacity of the refrigerant. When the boat continues to move rearward for a long period of time and there is a concern that the motor 3 or the inverter 6 is overheated, overheat of the motor 3 or the inverter 6 can be prevented by, for example, warning a boat operator or performing control to reduce the rotation speed of the motor 3.

[0074] As described above, in the marine propulsion device 1 according to the example of the present invention, the impeller 52 of the water pump 51 is connected to the output shaft 4 of the motor 3 via the one-way clutch 84. By such configuration, a rotation direction of the impeller 52 can be maintained to a certain direction. Therefore, it is possible to prevent the rotation direction of the impeller 52 from changing due to switching of the rotation direction of the output shaft 4 of the motor 3. Therefore, a lifespan of the impeller 52 can be prevented from being shortened.

[0075] Since the lifespan of the impeller 52 can be prevented from being shortened, it is possible to realize a miniaturized, simple-structured, or inexpensive marine propulsion device 1 that does not include a shift mechanism even when employing a rotary variable displacement water pump including a rubber impeller similarly to the marine propulsion devices of the related arts.

[0076] In the marine propulsion device 1 of the example, the motor 3 is disposed so that the extension direction of the output shaft 4 is the vertical direction, the transmission shaft 81 disposed coaxially with the output shaft 4, below the output shaft 4, and extending in the vertical direction is connected to the output shaft 4 via the one-way clutch 84, and the impeller 52 of the water pump 51 is attached to the transmission shaft 81. By such configuration, a structure in which only rotation in a certain direction of the output shaft 4 is transmitted to the impeller 52 can be constructed while the water pump 51 is disposed below the motor 3.

[0077] In the marine propulsion device 1 of the example, the drive gear 12 of the speed reducer 11 is attached to the output shaft 4 of the motor 3, the transmission shaft 81 disposed coaxially with the output shaft 4 and extending downward from the drive gear 12 is attached to the drive gear 12 via the one-way clutch 84, and the impeller 52 of the water pump 51 is attached to the transmission shaft 81. As such, using the drive gear 12 as a member that connects the output shaft 4 to the transmission shaft 81 via the one-way clutch 84, it is unnecessary to provide a separate member that connects the output shaft 4 to the transmission shaft 81 via the one-way clutch 84, and thus the number of parts in the marine propulsion device 1 can be reduced.

[0078] In the marine propulsion device 1 of the example, the impeller 52 of the water pump 51 is made of rubber. Therefore, self-priming capability and discharge capability of the water pump 51 can be enhanced, and priming during start-up is unnecessary.

[0079] In the cooling device 41 provided in the marine propulsion device 1 of the example, the cooling mechanism 61 includes the heat exchanger 62 that cools the refrigerant using water outside the marine propulsion device 1, the cooling jackets (the motor cooling jacket 63 and the inverter cooling jacket 64) that cool the equipment requiring cooling using the refrigerant, and the circulation passage that circulates the refrigerant between the heat exchanger 62 and the cooling jackets. In other words, in the cooling device 41 provided in the marine propulsion device 1 of the example, the equipment requiring cooling is not cooled by flowing cooling water in the cooling jacket, and the equipment requirement cooling is cooled by flowing the refrigerant cooled by the cooling water in the heat exchanger 62 in the cooling jacket. According such configuration, by increasing heat capacity of the refrigerant, it is possible to sufficiently cool the equipment requiring cooling even when rotation of the impeller 52 of the water pump 51 is stopped. Methods for increasing heat capacity of the refrigerant include a method of increasing a flow rate of the refrigerant flowing in the circulation passage by, for example, selecting a refrigerant with large heat capacity for usage in the cooling mechanism 61 or increasing a flow area of the circulation passage, and a method of further increasing the flow rate of the refrigerant by connecting a storage portion that stores the refrigerant in midway of the circulation passage so that the refrigerant passes in the storage portion while circulating in the circulation passage.

[0080] In the marine propulsion device 1 of the example, the water pump 51 is disposed so that the water pump 51 overlaps with the motor 3 when the marine propulsion device 1 is viewed from above. That is, a position of the motor 3 and a position of the water pump 51 are substantially aligned with each other in the front-rear and left-right directions. By such configuration, the marine propulsion device 1 can be made more compact and the marine propulsion device 1 can be brought closer to the boat compared to a configuration in which the positions of the motor 3 and the water pump 51 are significantly offset to each other in the front-rear and left-right directions. The cooling device 41 can be made compact, and the supply passage, the discharge passage, or the circulation passage that connects between components in the cooling device 41 can be shortened.

Second Example

[0081] FIG. 6 is a cross-sectional view illustrating a marine propulsion device 91 according to a second example of the present invention cut along a position of the line A-A in FIG. 2 as viewed from the left. FIG. 7 illustrates an enlarged view of a portion of the marine propulsion device 91 in FIG. 6 including a water pump 96. In the marine propulsion device 91 according to the second example of the present invention, the same components as those in the marine propulsion device 1 according to the first example of the present invention are given the same reference numerals, and description thereof will be omitted or simplified.

[0082] As illustrated in FIG. 6, a cooling device provided in the marine propulsion device 91 in the second example of the present invention includes a water pump 96 that sends water outside the marine propulsion device 91, that is, cooling water, to the heat exchanger 62 via the supply passage. The water pump 96 is a rotary variable displacement water pump including a rubber impeller. The water pump 96 includes an impeller 97 and a pump case 99. The water pump 96 is disposed in a front part of the lower part in the middle case 25. The water pump 96 is disposed so that a rotation axis of the impeller 97 is coaxial with the drive shaft 14. The pump case 99 is attached to the upper surface of the lower case 27. Relative to an arrangement of the water pump 96, shapes or arrangements of each of a lower internal supply passage 94 and an upper internal supply passage 95 are partially different from shapes or arrangements of each of the lower internal supply passage 44 and the upper internal supply passage 45 in the first example.

[0083] The impeller 97 of the water pump 96 is connected to the drive shaft 14 via a one-way clutch 102 and a transmission shaft 101 having a cylindrical shape. Specifically, as illustrated in FIG. 7, the transmission shaft 101 having a cylindrical shape and coaxial with the drive shaft 14 is provided on an outer periphery of the drive shaft 14. An inner diameter of the transmission shaft 101 is larger than an outer diameter of the drive shaft 14. The drive shaft 14 is inserted in the transmission shaft 101 via a space. The transmission shaft 101 is supported by the drive shaft 14 via bearings 103 and 104 to be rotatable relative to the drive shaft 14. The transmission shaft 101 is supported to be rotatable by a portion of the middle case 25 via bearings 105 and 106. A sealing member 107 is provided between the drive shaft 14 and an upper end of the transmission shaft 101. In the example, since the transmission shaft is not attached to a drive gear 93 of a speed reducer 92, a shape of the drive gear 93 is partially different from a shape of the drive gear 12 according to the first example.

[0084] The transmission shaft 101 is attached to the outer periphery of the drive shaft 14 via the one-way clutch 102. Specifically, the one-way clutch 102 is provided between the transmission shaft 101 and the drive shaft 14, and the transmission shaft 101 is coupled to the drive shaft 14 via the one-way clutch 102. The one-way clutch 102 transmits rotation of the drive shaft 14 to the transmission shaft 101 only when the drive shaft 14 rotates in the direction that moves the boat forward.

[0085] The impeller 97 of the water pump 96 is attached to an outer periphery of the transmission shaft 101. Specifically, the transmission shaft 101 is inserted into a mounting hole 98A of a shaft portion 98 of the impeller 97, and the impeller 97 is coupled to the transmission shaft 101 to not be rotatable. Rotation of the drive shaft 14 is transmitted to the transmission shaft 101 and the transmission shaft 101 rotates only when the drive shaft 14 rotates in the direction that moves the boat forward by operating the one-way clutch 102. Therefore, the impeller 97 rotates only when the drive shaft 14 rotates in the direction that moves the boat forward.

[0086] According to the marine propulsion device 91 of the second example of the present invention having such configuration, as with the marine propulsion device 1 of the first example of the present invention, it is possible to prevent the rotation direction of the impeller 97 from changing due to switching of the rotation direction of the output shaft 4 of the motor 3, thereby preventing a lifespan of the impeller 97 from being shortened.

[0087] In the marine propulsion device 91 according to the second example of the present invention, the water pump 96 can be disposed in an approximately same position as in the marine propulsion device of the related art. Therefore, new marine propulsion devices can be manufactured efficiently or at low costs using parts of the marine propulsion devices of the related art.

[0088] In the first example, the transmission shaft 81 is attached to the drive gear 12 via the one-way clutch 84, and the impeller 52 of the water pump 51 is directly attached to the transmission shaft 81. Also in the second example, the transmission shaft 101 is attached to the drive shaft 14 via the one-way clutch 102, and the impeller 97 of the water pump 96 is directly attached to the transmission shaft 101. However, in the present invention, a method of attaching the impeller of the water pump is not limited thereto. For example, as illustrated in FIG. 8A, an impeller 124 of a water pump 123 may be attached to an output shaft 122 of a motor 121 via a one-way clutch 125. As illustrated in FIG. 8B, an impeller 134 of a water pump 133 may be attached to a drive shaft 131 via a one-way clutch 135. As illustrated in FIG. 8C, an extension shaft 143 may be coupled to an output shaft 142 of a motor 141 to not be rotatable, and an impeller 145 of a water pump 144 may be attached to the extension shaft 143 via a one-way clutch 146. The extension shaft 143 is a specific example of a "rotation transmission member".

[0089] In each of the above-described examples, the rotary variable displacement water pump including a rubber impeller is used as the water pump 51 (96), but other types of water pumps including a rubber impeller may be used as the water pump in the cooling device provided in the marine propulsion device of the present invention.

[0090] In each of the above-described examples, an example is given in which the motor 3 and the inverter 6 are cooled by the cooling mechanism 61, but the present invention is not limited thereto, and the cooling mechanism may cool only the motor, or cool other equipment in addition to the motor and the inverter.

[0091] The configuration of the cooling mechanism of the cooling device of the present invention is not limited to that described in the example. For example, a direction of the refrigerant flowing in the circulation passage of the cooling mechanism may be reversed.

[0092] The present invention is not limited to the outboard motor, and can also be applied to other types of marine propulsion devices such as inboard/outboard motors.

[0093] 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 marine propulsion devices incorporating such modifications are also included in the technical concept of the present invention.

[0094] According to the present invention, shortening of a lifespan of the impeller of the water pump can be prevented even when a motor is used as a power source for rotating a propeller and a rotation direction of an output shaft of the motor is switched.