outboard motor

Abstract

In an outboard motor in which a lower unit rotates relative to an upper unit, pressure loss in a supply passage that supplies cooling water from the lower unit to the upper unit is reduced, thereby smoothing the supply of cooling water. [Solution] The outboard motor (1) includes a connecting mechanism (40) that connects the lower unit (21) to the upper unit (2) so that the lower unit (21) can rotate about the axis of the drive shaft (31), and a cooling device. The connecting mechanism (40) is configured so that a first shaft (41) provided on the lower unit (21) is rotatably inserted inside a second shaft (42) provided on the upper unit (2), and the drive shaft (31) is inserted inside the first shaft (41) with a space (65) interposed between them. The cooling device includes a supply passage that supplies water taken into the lower unit (21) from a water intake (62) to the upper unit (2) as cooling water, and part of the supply passage is formed by the space (65) between the drive shaft (31) and the first shaft (41).

Description

[Technical Field]

[0001] The present invention relates to an outboard motor that can steer a boat by rotating a lower part of a body on which a propeller is mounted relative to an upper part of the body on which a power source that rotates the propeller is mounted. [Background technology]

[0002] An outboard motor is known that can steer a boat by rotating a lower part of the body on which a propeller is mounted relative to an upper part of the body on which a power source that rotates the propeller is mounted. Such an outboard motor is described in U.S. Patent No. 10,800,502 (hereinafter referred to as "Patent Document 1").

[0003] Figure 10(A) shows a schematic diagram of the entire outboard motor 1020 having a configuration similar to that of the outboard motor described in Patent Document 1. Figure 10(B) shows details of the portion of the outboard motor 1020 in Figure 10(A) surrounded by a two-dot chain line.

[0004] 10(A), the outboard motor 1020 includes an upper unit UA disposed at the top of the outboard motor 1020, and a lower unit UB disposed at the bottom of the outboard motor 1020. The upper unit UA includes a power head 1022 including a power source that rotates a propeller 1043, a drive shaft housing 1026, and a steering housing 1028. On the other hand, the lower unit UB includes a lower gear case 1038, a propeller shaft 1040, and a propeller 1043.

[0005] The outboard motor 1020 also includes a drive shaft 1024 that transmits the rotation of a power source included in a power head 1022 to a propeller shaft 1040. The drive shaft 1024 passes from the power head 1022 through a drive shaft housing 1026 and a steering housing 1028 in that order, and enters a lower gear case 1038.

[0006] The outboard motor 1020 also includes a coupling mechanism that couples the lower unit UB to the upper unit UA rotatably about the axis of the drive shaft 1024. As shown in FIG. 10(B), the coupling mechanism is primarily composed of a center column 1035 and a steering column 1046. The center column 1035 is formed in the steering housing 1028. A through bore 1036 is formed in the center column 1035 and extends from the top to the bottom of the steering housing 1028. The steering column 1046 is fixed to the lower gear case 1038 and extends upward from the top of the lower gear case 1038 toward the steering housing 1028. A through bore 1052 that passes through the steering column 1046 is formed in the steering column 1046. A steering column 1046 is inserted into the through bore 1036 of the center column 1035 from below the through bore 1036. The steering column 1046 is supported by the center column 1035 via bearings so as to be rotatable relative to the center column 1035. Furthermore, a drive shaft 1024 is inserted into the through bore 1052 of the steering column 1046.

[0007] The outboard motor 1020 also includes a steering actuator 1056 as a power source for rotating the lower unit UB relative to the upper unit UA. The steering actuator 1056 is fixed inside the steering housing 1028. A rack and pinion is provided inside the steering housing 1028 for rotating the steering column 1046 relative to the center column 1035 using the power of the steering actuator 1056. Driving the steering actuator 1056 causes the lower unit UB to rotate horizontally relative to the upper unit UA, thereby enabling the boat to steer.

[0008] The outboard motor 1020 also has a cooling water conduit that carries cooling water from the lower gear case 1038 to the power head 1022 via the steering housing 1028 to cool the power head 1022 and other components. Specifically, as shown in FIG. 10(A), the outboard motor 1020 has an intake port 1314, a first cooling water conduit 1302, a second cooling water conduit 1304, a third cooling water conduit 1306, and a cooling water pump 1308. The intake port 1314 and the first cooling water conduit 1302 are provided in the lower gear case 1038. The second cooling water conduit 1304, the third cooling water conduit 1306, and the cooling water pump 1308 are provided in the steering housing 1028. Water outside the outboard motor 1020 flows from the intake port 1314 into the lower gear case 1038 as cooling water. The cooling water then flows through the first cooling water conduit 1302, then into the second cooling water conduit 1304, and into the steering housing 1028. The cooling water then flows through the second cooling water conduit 1304, then into the third cooling water conduit 1306, and toward the power head 1022.

[0009] The outboard motor 1020 also has an annular passage 1316 as part of the second cooling water conduit 1304. The annular passage 1316 is formed around the entire circumference of the center column 1035, on the outer periphery of the lower part of the center column 1035. Here, FIG. 10(C) shows the annular passage 1316 as viewed from above. Also, P in FIGS. 10(B) and 10(C) indicates the forward-most position in the annular passage 1316. Q in FIGS. 10(B) and 10(C) indicates the rearward-most position in the annular passage 1316. The cooling water that has flowed through the first cooling water conduit 1032 flows into position P of the annular passage 1316 and then flows within the annular passage 1316 generally toward position Q, as indicated by the arrow in FIG. 10(C).

[0010] When the lower unit UB rotates relative to the upper unit UA, the position of the outlet of the first cooling water conduit 1302 provided on the lower unit UB side is displaced relative to the position of the second cooling water conduit 1304 provided on the upper unit UA side. The annular flow path 316 is formed in an annular shape so as to follow the trajectory of displacement of the outlet of the first cooling water conduit 1302 when the lower unit UB rotates. Therefore, even if the position of the outlet of the first cooling water conduit 1302 is displaced due to the rotation of the lower unit UB, the connection between the first cooling water conduit 1302 and the second cooling water conduit 1304 is maintained via the annular flow path 1316.

[0011] The structure of the annular channel 1316 in the outboard motor 1020 is substantially the same as the structure of the annular channel 316 in the outboard motor described in Patent Document 1. [Prior art documents] [Patent documents]

[0012] [Patent Document 1] U.S. Patent No. 10,800,502 Summary of the Invention [Problem to be solved by the invention]

[0013] Generally, outboard motors are equipped with equipment that requires cooling (hereinafter referred to as "equipment requiring cooling"), such as a power source that rotates the propeller. To cool the equipment requiring cooling, many outboard motors are equipped with a cooling device that takes in water from outside the outboard motor (e.g., seawater) into the outboard motor and uses that water as cooling water to cool the equipment requiring cooling. The cooling device includes a water intake provided on the bottom of the outboard motor (the part submerged below the water surface), a supply passage for supplying the water from outside the outboard motor that flows into the outboard motor from the water intake to the equipment requiring cooling as cooling water, and a pump that sends the cooling water via the supply passage to the equipment requiring cooling.

[0014] When a cooling system is installed in an outboard motor having a structure in which the lower unit rotates relative to the upper unit as described above, a water intake is provided in the lower unit, and a supply passage is provided in the outboard motor to supply water flowing into the lower unit from the water intake as cooling water to the equipment requiring cooling. In this case, the equipment requiring cooling, such as the power source that rotates the propeller, is provided in the upper unit, so the supply passage must be provided from the lower unit to the upper unit. Furthermore, because the lower unit rotates relative to the upper unit, when providing a supply passage from the lower unit to the upper unit, the structure of the supply passage must be considered so that the rotation of the lower unit does not cause the supply passage to be interrupted or the flow of cooling water through the supply passage to be impeded.

[0015] 10(A) to 10(C), an intake port 1314, which corresponds to a water intake port, is provided in a portion of the lower unit UB that is submerged underwater. Cooling water conduits 1302, 1303, and 1306, which correspond to supply passages that supply water that has flowed into the lower unit UB from the intake port 1314 to the upper unit UA, are provided from the lower unit UB to the upper unit UA as a whole. The outboard motor 1020 is also provided with an annular passage 1316, which maintains the connection between the first cooling water conduit 1302 and the second cooling water conduit 1304 via the annular passage 1316, even if the position of the outlet of the first cooling water conduit 1302 is displaced due to rotation of the lower unit UB.

[0016] However, in the outboard motor 1020, the annular passage 1316 is formed on the outer periphery of the center column 1035 of the steering housing 1028, as shown in Figure 10(B). Therefore, the circumferential length of the circle described by the annular passage 1316 is equal to the circumferential length of the outer periphery of the center column 1035, and therefore the annular passage 1316 may be long. Therefore, there is a risk that pressure loss caused by the cooling water flowing inside the annular passage 1316 may become large.

[0017] Furthermore, the annular channel 316 in the outboard motor described in Patent Document 1 has substantially the same structure as the annular channel 1316 in the outboard motor 1020. Therefore, the annular channel may be long in the outboard motor described in Patent Document 1 as well, which may increase the pressure loss caused by the cooling water flowing through the annular channel.

[0018] The present invention has been made in view of the problems described above, and an object of the present invention is to provide an outboard motor in which the lower unit rotates relative to the upper unit, in which pressure loss in the supply passage that supplies cooling water from the lower unit to the upper unit can be reduced, thereby facilitating the supply of cooling water. [Means for solving the problem]

[0019] In order to solve the above problems, the present invention provides an outboard motor comprising an upper unit including a drive motor, a lower unit including a propeller shaft, a drive shaft that transmits rotation of the drive motor to the propeller shaft, a connecting mechanism that connects the lower unit to the upper unit so that the lower unit can rotate about the axis of the drive shaft, and a cooling device, wherein the cooling device is provided in the upper unit and includes a cooling mechanism that uses cooling water to cool devices that require cooling, including the drive motor, a water intake that takes in water from outside the outboard motor into the lower unit as cooling water, and a cooling mechanism that is provided from the lower unit to the upper unit and takes in water from outside the outboard motor into the lower unit. and a supply passage that supplies cooled cooling water to the cooling mechanism, the connecting mechanism comprising: a cylindrical first shaft portion provided on the upper part of the lower unit and having an axis coaxial with that of the drive shaft; and a cylindrical second shaft portion provided on the lower part of the upper unit and having an axis coaxial with that of the drive shaft, one of the first shaft portion and the second shaft portion being inserted inside the other shaft portion so as to be rotatable relative to the other shaft portion, the drive shaft being inserted inside the one shaft portion via a space, and a part of the supply passage being formed by the space between the drive shaft and the one shaft portion. [Effects of the Invention]

[0020] According to the present invention, in an outboard motor in which the lower unit rotates relative to the upper unit, pressure loss in the supply passage that supplies cooling water from the lower unit to the upper unit can be reduced, thereby facilitating the supply of cooling water. [Brief explanation of the drawings]

[0021] [Figure 1] FIG. 1 is an explanatory diagram showing an outboard motor according to an embodiment of the present invention as viewed from the left. [Figure 2] FIG. 1 is an explanatory diagram showing an outboard motor according to an embodiment of the present invention as viewed from the rear. [Figure 3] 3 is a cross-sectional view of the outboard motor taken along the line AA in FIG. 2 as viewed from the left. [Figure 4] 4 is an enlarged cross-sectional view of the outboard motor in FIG. 3, showing a portion where a reduction gear transmission, a connecting mechanism, a steering motor, and a worm gear mechanism are provided. [Figure 5] 5(A) is a cross-sectional view showing an upper unit of the outboard motor in FIG. 4, and FIG. 5(B) is a cross-sectional view showing a lower unit of the outboard motor in FIG. [Figure 6] 5 is a cross-sectional view taken along line BB in FIG. 4, showing the middle case of the outboard motor, and the steering motor and worm gear mechanism disposed within the middle case, as viewed from above. [Figure 7] FIG. 1A is a block diagram showing the configuration of a cooling device provided in an outboard motor according to an embodiment of the present invention; FIG. 1B is a block diagram showing the configuration of another cooling device that can be provided in an outboard motor according to the present invention; and FIG. 1C is a block diagram showing the configuration of yet another cooling device that can be provided in an outboard motor according to the present invention. [Figure 8] 4 is an enlarged cross-sectional view of the outboard motor in FIG. 3, showing a portion where a water intake, a water pump, a reduction gear cooling chamber, and a heat exchanger are provided. FIG. [Figure 9] 9(A) is an external view showing the state in which the communication passage forming member in an outboard motor of an embodiment of the present invention is seen from above, (B) is a cross-sectional view showing the state in which the communication passage forming member is cut along the cutting line CC in FIG. 9(A) as seen from the left, and (C) is a cross-sectional view showing the state in which the communication passage forming member is cut along the cutting line DD in FIG. 9(A) as seen from the front left. [Figure 10] 10(A) is a schematic diagram showing the overall configuration of a conventional outboard motor, (B) is an explanatory diagram showing an enlarged view of the area surrounded by the two-dot chain line in FIG. 10(A), and (C) is an explanatory diagram showing the annular flow passage in FIG. 10(B) as viewed from above. DETAILED DESCRIPTION OF THE INVENTION

[0022] An outboard motor according to an embodiment of the present invention includes an upper unit including a drive motor, a lower unit including a propeller shaft, a drive shaft that transmits rotation of the drive motor to the propeller shaft, a connecting mechanism that connects the lower unit to the upper unit so that the lower unit can rotate about the axis of the drive shaft, and a cooling device. In the outboard motor according to this embodiment, the cooling device includes a cooling mechanism that is provided in the upper unit and uses cooling water to cool components that require cooling, including the drive motor, a water intake that draws water from outside the outboard motor into the lower unit as cooling water, and a supply passage that extends from the lower unit to the upper unit and supplies the cooling water drawn into the lower unit to the cooling mechanism. The connecting mechanism includes a cylindrical first shaft that is provided at the top of the lower unit and has an axis coaxial with the axis of the drive shaft, and a cylindrical second shaft that is provided at the bottom of the upper unit and has an axis coaxial with the axis of the drive shaft. In the connecting mechanism, one of the first and second shafts is inserted inside the other shaft so as to be rotatable relative to the other shaft. A drive shaft is inserted inside one of the shafts via a space. Furthermore, part of the supply passage in the cooling mechanism is formed by the space between the drive shaft and one of the shafts.

[0023] In the outboard motor of this embodiment, the drive shaft is inserted into the innermost of the two shafts of the connecting mechanism, i.e., the first shaft and the second shaft. The drive shaft transmits rotation of the drive motor to the propeller shaft, so it must be rotatable relative to the innermost of the two shafts of the connecting mechanism. Therefore, the drive shaft is inserted into the innermost shaft with a gap between them, and an annular space exists between the drive shaft and the innermost shaft. In the outboard motor of this embodiment, part of the supply passage that supplies cooling water taken in by the lower unit to the cooling mechanism provided in the upper unit is formed by the annular space existing between the drive shaft and the innermost of the two shafts of the connecting mechanism.

[0024] The circumferential length of the annular space existing between the drive shaft and the innermost of the two shafts of the connecting mechanism is longer than the outer periphery of the drive shaft and shorter than the inner periphery of the innermost of the two shafts of the connecting mechanism. On the other hand, the circumferential length of the circle described by the annular flow passage 1316 in the outboard motor 1020 shown in Figures 10(A) to 10(C) is equal to the outer periphery of the center column 1035, which is located further outward from the steering column 1046, which is located outward from the drive shaft 1024. Therefore, if the sizes of the connecting mechanisms in the outboard motor of this embodiment and the outboard motor 1020 are equal to each other, for example, if the inner diameter of the innermost of the two shafts in the connecting mechanism in the outboard motor of this embodiment is equal to the inner diameter of the steering column 1046 in the outboard motor 1020, and the outer diameter of the outermost of the two shafts in the connecting mechanism in the outboard motor of this embodiment is equal to the outer diameter of the center column 1035 in the outboard motor 1020, then the circumferential length of the annular space existing between the drive shaft and the innermost of the two shafts in the connecting mechanism in the outboard motor of this embodiment will be shorter than the circumferential length of the circle described by the annular flow path 1316 in the outboard motor 1020. Furthermore, if the size of the connecting mechanism in the outboard motor of this embodiment is equal to the size of the connecting mechanism in the outboard motor described in Patent Document 1, the circumferential length of the annular space existing between the drive shaft and the innermost of the two shafts of the connecting mechanism in the outboard motor of this embodiment is shorter than the circumferential length of the circle described by the annular channel 316 in the outboard motor described in Patent Document 1. Therefore, according to the outboard motor of this embodiment, by forming a portion of the supply passage using the annular space existing between the drive shaft and the innermost of the two shafts of the connecting mechanism, the portion of the supply passage can be made shorter than both the annular channel 1316 in the outboard motor 1020 and the annular channel 316 in the outboard motor described in Patent Document 1. This reduces pressure loss caused by the cooling water flowing through the portion of the supply passage.Therefore, the cooling water taken into the lower unit can be smoothly supplied to the cooling mechanism provided in the upper unit. [Example]

[0025] An outboard motor according to an embodiment of the present invention will be described with reference to Figures 1 to 9. In describing the embodiment, when directions such as up (Ud), down (Dd), front (Fd), rear (Bd), left (Ld), and right (Rd) are mentioned, they will be indicated by arrows drawn at the bottom left in Figures 1 to 6, 8, and 9.

[0026] (Basic configuration of outboard motor) Fig. 1 shows an outboard motor 1 according to an embodiment of the present invention as seen from the left. Fig. 2 shows the outboard motor 1 as seen from the rear. Fig. 3 shows a cross section of the outboard motor 1 taken along line AA in Fig. 2 as seen from the left. Fig. 4 shows an enlarged view of the portion of the outboard motor in Fig. 3 where the reduction gear 12, connecting mechanism 40, steering motor 45, and worm gear mechanism 51 are provided.

[0027] The outboard motor 1 is a device for propelling a boat, and is mounted on the transom 120 of the boat, as shown in Fig. 1. As shown in Fig. 3, the outboard motor 1 includes an upper unit 2 that includes a drive motor 3, an inverter 6, and a reduction gear 12, and a lower unit 21 that includes a propeller 22, a propeller shaft 23, and a rotation transmission mechanism 24. The lower unit 21 is disposed below and connected to the upper unit 2. The outboard motor 1 also includes a drive shaft 31 that extends vertically from the upper unit 2 to the lower unit 21.

[0028] The drive motor 3 is a power source that rotates the propeller 22, and is, for example, an AC motor. The drive motor 3 includes a rotor, a stator, and an output shaft 4 that outputs the rotation of the rotor. The drive motor 3 also includes a motor case 5. The rotor, stator, and the rest of the output shaft 4, excluding the end that extracts power, are housed in the motor case 5. The drive motor 3 is disposed on top of the outboard motor 1. When the outboard motor 1 is mounted on a boat, the drive motor 3 is located above the water surface. The drive motor 3 is disposed so that the extension direction of the output shaft 4 is vertical.

[0029] The inverter 6 is a device that controls the drive of the drive motor 3. The inverter 6 includes an inverter main body 7 that is provided with circuits and the like that control the drive of the drive motor 3, and an inverter case 8 that houses the inverter main body 7. The inverter 6 is disposed above the drive motor 3. The inverter 6 is also attached to the drive motor 3 via an inverter mounting member 10.

[0030] The reduction gear 12 is a device that reduces the rotation speed of the output shaft 4 of the drive motor 3 and transmits it to the drive shaft 31. The reduction gear 12 is disposed below the drive motor 3. As shown in FIG. 4, the reduction gear 12 includes a drive gear 13 and a driven gear 14. The drive gear 13 is connected to the lower end of the output shaft 4 of the drive motor 3 and rotates integrally with the output shaft 4. The driven gear 14 is disposed in front of the drive gear 13. The driven gear 14 is also connected to the upper end of the drive shaft 31. The driven gear 14 is also in mesh with the drive gear 13. The gear ratio between the drive gear 13 and the driven gear 14 (the number of teeth of the driven gear 14 / the number of teeth of the drive gear 13) is greater than 1.

[0031] Additionally, the upper unit 2 of the outboard motor 1 is provided with a middle case 15. The middle case 15 is disposed below the drive motor 3 and is attached to the drive motor 3. The middle case 15 accommodates the reduction gear 12, the upper portion of the drive shaft 31, a steering motor 45 (described later), and a worm gear mechanism 51 (described later). Although not shown in detail, the middle case 15 is divided into an upper case portion that accommodates the reduction gear 12 and a lower case portion that accommodates the steering motor 45 and the worm gear mechanism 51, and the upper and lower case portions are joined together by joining members such as bolts.

[0032] As shown in Figure 3, the propeller shaft 23 is disposed at the bottom of the outboard motor 1. When the outboard motor 1 is mounted on a boat, the propeller shaft 23 is located below the water surface. The propeller shaft 23 extends in the fore-and-aft direction. The propeller 22 is coupled to the rear of the propeller shaft 23 and rotates integrally with the propeller shaft 23.

[0033] The rotation transmission mechanism 24 is a mechanism that transmits the rotation of the drive shaft 31 to the propeller shaft 23. The rotation transmission mechanism 24 includes two bevel gears 25, 26 that mesh with each other. One of the bevel gears, 25, is coupled to the lower end of the drive shaft 31 and rotates integrally with the drive shaft 31. The other bevel gear, 26, is coupled to the front end of the propeller shaft 23 and the propeller shaft 23 rotates integrally with the bevel gear 26.

[0034] The lower unit 21 of the outboard motor 1 is provided with a lower case 27. The rotation transmission mechanism 24 and the front part of the propeller shaft 23 are housed in the lower case 27. An anti-cavitation plate 28 is provided in a portion of the lower case 27 located above the propeller 22. A steering case 29 is provided at the top of the lower case 27.

[0035] The drive shaft 31 is a shaft that transmits the rotation of the drive motor 3 after being reduced in speed by the reduction gear 12 to the propeller shaft 23. As described above, the driven gear 14 of the reduction gear 12 is coupled to the upper end of the drive shaft 31, and the drive shaft 31 rotates integrally with the driven gear 14. The bevel gear 25 of the rotation transmission mechanism 24 is coupled to the lower end of the drive shaft 31. The drive shaft 31 is also disposed forward of the output shaft 4 of the drive motor 3. In the reduction gear 12, the drive gear 13 is coupled to the output shaft 4 of the drive motor 3, and the driven gear 14, which is disposed forward of the drive gear 13, is coupled to the drive shaft 31. As a result, the rotation of the output shaft 4 of the drive motor 3 is transmitted to the drive shaft 31, which is disposed forward of the output shaft 4 of the drive motor 3.

[0036] The drive motor 3 is driven by the control of the inverter 6, causing the output shaft 4 to rotate. The rotation of the output shaft 4 is transmitted to the drive shaft 31 while being reduced in speed by the reduction gear 12, causing the drive shaft 31 to rotate. The rotation of the drive shaft 31 is transmitted to the propeller shaft 23 by the rotation transmission mechanism 24, causing the propeller shaft 23 and the propeller 22 to rotate. The rotation of the propeller 22 generates a propulsive force for the vessel.

[0037] The outboard motor 1 also includes a mounting mechanism 33 for mounting the outboard motor 1 to the boat. The mounting mechanism 33 is located in front of the upper unit 2. The mounting mechanism 33 includes a pair of left and right clamp brackets 34 that secure the upper unit 2 to the transom 120 of the boat, and a mount bracket 35 that connects the clamp brackets 34 to the upper unit 2. The front portion of the mount bracket 35 is located between the pair of clamp brackets 34 and is connected to the pair of clamp brackets 34 via a tilt shaft 39. An upper mount 36 that supports the upper portion of the upper unit 2 is provided at the top of the rear portion of the mount bracket 35. The upper mount 36 supports a portion of the upper portion of the upper unit 2 that is located between the drive motor 3 and the inverter 6. A lower mount 37 that supports the lower portion of the upper unit 2 is provided at the bottom of the rear portion of the mount bracket 35. The lower mount 37 supports a portion of the lower portion of the upper unit 2 that is located above the portion where the driven gear 14 of the reduction gear 12 is located. Additionally, the mount bracket 35 can rotate vertically about the axis of the tilt shaft 39 relative to the clamp bracket 34. This allows the outboard motor 1 to be rotated (tilted up and down) vertically relative to the boat. Unlike a typical swivel bracket, the mount bracket 35 does not have a structure for rotating the outboard motor left and right. As will be described later, the outboard motor 1 has the function of rotating the lower unit 21 left and right relative to the upper unit 2. Therefore, even if the mount bracket 35 does not have a structure for rotating the outboard motor 1 left and right, the orientation of the propeller 22 left and right can be changed and the boat can be steered.

[0038] (Configuration regarding rotation of lower unit) Figure 5(A) shows the upper unit 2 separated from the lower unit 21 in the outboard motor 1 in Figure 4. Figure 5(B) shows the lower unit 21 separated from the upper unit 2 in the outboard motor 1 in Figure 4. Figure 6 shows the middle case 15 of the outboard motor 1 cut along the cutting line BB in Figure 4, as well as the steering motor 45 and worm gear mechanism 51 arranged inside the middle case 15, as viewed from above.

[0039] The outboard motor 1 has the function of steering the boat by rotating the lower unit 21 left and right relative to the upper unit 2. For this function, the outboard motor 1 is equipped with a connecting mechanism 40, a steering motor 45, and a worm gear mechanism 51, as shown in Figures 4, 5(A), 5(B), and 6.

[0040] The connecting mechanism 40 connects the lower unit 21 to the upper unit 2 so as to be rotatable about the axis K of the drive shaft 31. As shown in FIG. 4 , the connecting mechanism 40 includes a first shaft 41 provided on the upper part of the lower unit 21, a second shaft 42 provided on the lower part of the upper unit 2, and a bearing 43, and is formed by rotatably connecting the first shaft 41 to the second shaft 42 via the bearing 43. More specifically, as shown in FIG. 5(B) , a steering case 29 is attached to the top of the lower case 27 provided on the lower unit 21 so as to cover the entire upper surface of the lower case 27. The first shaft 41 is provided on this steering case 29. The first shaft 41 is formed in a cylindrical shape having an axis coaxial with the axis K of the drive shaft 31 and extends upward from the upper surface of the steering case 29. On the other hand, as shown in FIG. 5(A), the second shaft portion 42 is provided at the bottom of the middle case 15, which is located at the bottom of the upper unit 2. The second shaft portion 42 is formed in a cylindrical shape with an axis coaxial with the axis K of the drive shaft 31. The inner diameter of the second shaft portion 42 is larger than the outer diameter of the first shaft portion 41. As shown in FIG. 4, the first shaft portion 41 is inserted into the inside of the second shaft portion 42 from below. A bearing 43 is provided between the inner peripheral surface of the second shaft portion 42 and the outer peripheral surface of the first shaft portion 41. The first shaft portion 41 is coupled to the second shaft portion 42 so as to be rotatable about the axis K of the drive shaft 31 relative to the second shaft portion 42, and at the same time, is coupled to the second shaft portion 42 so as not to be displaced vertically relative to the second shaft portion 42. The drive shaft 31 is inserted inside the first shaft portion 41 via a space 65. The drive shaft 31 is rotatable relative to the first shaft portion 41 .

[0041] The steering motor 45 is a power source that rotates the lower unit 21 relative to the upper unit 2, and is, for example, a DC or AC electric motor. As shown in FIG. 5(A), the steering motor 45 is mounted on the upper unit 2 and disposed within the middle case 15. As shown in FIG. 4, the steering motor 45 is disposed below the drive motor 3 and rearward of the drive shaft 31. When the outboard motor 1 is viewed from above, at least a portion of the steering motor 45 overlaps with the drive motor 3. The steering motor 45 is disposed rearward of the worm gear mechanism 51 and rearward of the worm wheel 53 and the worm 52. The steering motor 45 includes a rotor, a stator, and an output shaft 46 that outputs the rotation of the rotor. As shown in FIG. 6, the steering motor 45 is disposed so that the axis L of the output shaft 46 is located on a plane perpendicular to the axis K of the drive shaft 31. The steering motor 45 is disposed so that the extension direction of the output shaft 46 is the left-right direction of the outboard motor 1. Further, the steering motor 45 is attached to a steering motor attachment portion 47 , and the steering motor attachment portion 47 is fixed inside the middle case 15 .

[0042] Worm gear mechanism 51 is a mechanism that transmits the rotation of steering motor 45 to lower unit 21 to rotate lower unit 21 relative to upper unit 2. As shown in FIG. 4, worm gear mechanism 51 is provided between upper unit 2 and lower unit 21. Worm gear mechanism 51 is also disposed below reduction gear 12. Worm gear mechanism 51 includes worm 52 that rotates with the rotation of steering motor 45, and worm wheel 53 that meshes with worm 52.

[0043] As shown in FIG. 5(B), the worm wheel 53 is fixed to the steering case 29 provided in the lower unit 21. Specifically, the worm wheel 53 is fixed to the upper end of the first shaft portion 41 using a connecting member such as a bolt. This allows the lower unit 21 to rotate integrally with the worm wheel 53. The worm wheel 53 is also disposed coaxially with the drive shaft 31 on the outer circumferential side of the drive shaft 31. As shown in FIG. 4, the worm wheel 53 is located below the driven gear 14 of the reduction gear transmission 12 within the middle case 15.

[0044] 6, the worm 52 is disposed rearward of the worm wheel 53 so that its axis M extends in the left-right direction of the outboard motor 1. The worm 52 is disposed between the steering motor 45 and the worm wheel 53. The worm 52 is disposed so that its axis M is parallel to the axis L of the output shaft 46 of the steering motor 45. The worm 52 is attached to the steering motor mounting portion 47 together with the steering motor 45.

[0045] A gear 54 is provided at the left end of the output shaft 46 of the steering motor 45. The gear 54 is coupled to the output shaft 46 and rotates integrally with the output shaft 46. A gear 55 is provided at the left end of the shaft portion of the worm 52. The gear 55 is coupled to the shaft portion of the worm 52 and the worm 52 rotates integrally with the gear 55. The gears 54 and 55 mesh with each other.

[0046] When the steering motor 45 is driven to rotate the output shaft 46 of the steering motor 45, the rotation is transmitted to the worm 52 via gears 54 and 55, causing the worm 52 to rotate. The rotation of the worm 52 is then transmitted to the worm wheel 53, causing the worm wheel 53 to rotate. The rotation of the worm wheel 53 causes the lower unit 21 to rotate left or right relative to the upper unit 2. By rotating the lower unit 21 left or right in this way, the left-right direction of the propeller 22 can be changed, and the boat can be steered. Furthermore, by rotating the lower unit 21 180 degrees left or right relative to the upper unit 2, the direction of the propeller 22 can be changed 180 degrees. This allows the boat to move backward without rotating the drive motor 3 in the reverse direction.

[0047] (cooling device) Figure 7(A) shows the configuration of the cooling device 61 provided in the outboard motor 1 of this embodiment. Figure 7(B) shows the configuration of another cooling device 101 that can be provided in the outboard motor of the present invention. Figure 7(C) shows the configuration of yet another cooling device 103 that can be provided in the outboard motor of the present invention. Figure 8 shows an enlarged view of the portion of the outboard motor 1 of this embodiment in Figure 3 where the water intake 62, water pump 77, reduction gear cooling chamber 86, and heat exchanger 87 are provided.

[0048] The outboard motor 1 is equipped with a liquid-cooling type cooling device 61 that cools the equipment that needs to be cooled and is provided in the outboard motor 1. Specifically, the equipment that needs to be cooled and is provided in the outboard motor 1 is the reduction gear 12, the drive motor 3, and the inverter 6.

[0049] 7(A), the cooling device 61 includes a water intake 62, a supply passage, a water pump 77, a cooling mechanism 85, a discharge passage 81, and a drain outlet 83. The supply passage also includes a lower supply passage 64, a space 65, a communication passage 66, and an upper supply passage 75.

[0050] The water intake 62 is an opening through which water from outside the outboard motor 1 is taken into the lower unit 21 as cooling water. The water intake 62 is provided in the lower unit 21. Specifically, as shown in FIG. 1 , the water intake 62 is provided in the front part of the lower case 27, below the anti-cavitation plate 28.

[0051] The supply passage is a passage that supplies cooling water taken into the lower unit 21 to the cooling mechanism 85. Since the water intake port 62 is provided in the lower unit 21 and the cooling mechanism 85 is provided in the upper unit 2 as will be described later, the supply passage is provided from the lower unit 21 to the upper unit 2. As shown in FIG. 8 , the supply passage is formed by sequentially connecting the lower supply passage 64, the space 65, the communication passage 66, and the upper supply passage 75.

[0052] Lower supply passage 64 is a passage that connects water intake port 62 and the suction port of water pump 77. Lower supply passage 64 is provided in lower unit 21. Specifically, lower supply passage 64 is configured by, for example, a hole formed in lower case 27. Lower supply passage 64 extends in the vertical direction between water intake port 62 and the suction port of water pump 77. The upper end side of lower supply passage 64 is connected to space 65 via the suction port of water pump 77, the inside of pump case 79 of water pump 77, and discharge port 80 of water pump 77.

[0053] A space 65 exists between the drive shaft 31 and the first shaft portion 41. As described above, the connecting mechanism 40 is configured so that the first shaft portion 41 is inserted inside the second shaft portion 42. The drive shaft 31 is inserted inside the first shaft portion 41 via the space 65. The drive shaft 31 can rotate relative to the first shaft portion 41. The space 65 between the drive shaft 31 and the first shaft portion 41 is a gap necessary to allow the drive shaft 31 to rotate relative to the first shaft portion 41. In the outboard motor 1, this space 65 between the drive shaft 31 and the first shaft portion 41 is used as part of the supply passage. The axis K of the drive shaft 31 and the axis of the first shaft portion 41 each extend in the vertical direction, and the drive shaft 31 is inserted inside the first shaft portion 41 so as to pass through the center of the first shaft portion 41. Therefore, the space 65 between the drive shaft 31 and the first shaft portion 41 has an annular or cylindrical shape with an axis extending in the vertical direction.

[0054] The communication passage 66 is a passage that connects the space 65 and the upper supply passage 75, providing communication between them. The communication passage 66 is formed by a communication passage forming member 67 that is provided at the opening on the upper side of the first shaft portion 41.

[0055] Here, Fig. 9(A) shows the communicating passage forming member 67 as viewed from above. Fig. 9(B) shows a cross section of the communicating passage forming member 67 cut along section line CC in Fig. 9(A) as viewed from the left (bottom in Fig. 9(A)). Fig. 9(C) shows a cross section of the communicating passage forming member 67 cut along section line DD in Fig. 9(A) as viewed from the front left (bottom left in Fig. 9(A)). Note that in Figs. 9(A) to 9(C), the upper supply passage 75 is indicated by a two-dot chain line. Furthermore, in Figs. 9(B) and 9(C), the drive shaft 31, the first shaft portion 41, and the space 65 are indicated by two-dot chain lines.

[0056] The communication passage forming member 67 is a member that forms a communication passage 66 in the supply passage, which connects a space 65 between the drive shaft 31 and the first shaft portion 41 with the upper supply passage 75. As shown in Figures 9(A) to 9(C), the communication passage forming member 67 includes a cover portion 68 attached to the upper opening of the first shaft portion 41, a cylindrical portion 69 that covers the opening on the inlet end side of the upper supply passage 75, a shaft insertion hole 71 into which the drive shaft 31 is inserted, and a communication hole 72 that connects the space 65 with the inside of the cylindrical portion 69.

[0057] The lid portion 68 is formed in a cylindrical shape with a diameter that is approximately equal to (strictly speaking, slightly smaller than) the diameter of the upper opening of the first shaft portion 41. The lid portion 68 is disposed coaxially with the first shaft portion 41. The lid portion 68 is inserted into the first shaft portion 41 from above the first shaft portion 41 so as to be rotatable relative to the first shaft portion 41. In this way, the lid portion 68 is attached to the upper opening of the first shaft portion 41 so as to cover the upper opening of the first shaft portion 41.

[0058] In addition, a sealing member 73 is provided between the outer periphery of the lid portion 68 and the inner periphery of the first shaft portion 41 to prevent cooling water that has flowed into the space 65 from leaking out of the space 65 through the gap between the outer periphery of the lid portion 68 and the inner periphery of the first shaft portion 41.

[0059] The shaft insertion hole 71 is provided in the center of the lid portion 68 and passes through the lid portion 68. The diameter of the shaft insertion hole 71 is slightly larger than the diameter of the drive shaft 31. The drive shaft 31 inserted into the shaft insertion hole 71 is rotatable relative to the communicating passage forming member 67.

[0060] The communication holes 72 are provided on the inner periphery of the lid portion 68, on the outer periphery side of the shaft insertion hole 71. A plurality of communication holes 72 are provided in the lid portion 68. Each communication hole 72 passes through the lid portion 68.

[0061] The cylindrical portion 69 extends upward while widening in diameter from the outer periphery of the cover portion 68. The cylindrical portion 69 has a generally cup-like shape. As shown in FIG. 9(A), a protruding portion 70 that protrudes radially outward from a portion of the outer periphery of the cylindrical portion 69 is formed. The opening on the inlet end side of the upper supply passage 75 faces downward and faces the protruding portion 70. The cylindrical portion 69 is fixed to the upper unit 2. Specifically, as shown in FIG. 8, the cylindrical portion 69 is fixed to the partition wall portion 16 in the middle case 15, which covers the reduction gear 12 from below, using a connecting member such as a bolt.

[0062] The tubular portion 69 is fixed to the partition wall portion 16 of the upper unit 2, and the lid portion 68 is inserted into the upper opening of the first shaft portion 41, thereby attaching the communicating passage forming member 67 between the first shaft portion 41 and the partition wall portion 16. Furthermore, with the communicating passage forming member 67 attached between the first shaft portion 41 and the partition wall portion 16, the peripheral edge of the opening on the inlet end side of the upper supply passage 75 is covered by the peripheral edge of the protruding portion 70, and the inlet end of the upper supply passage 75 and the inside of the tubular portion 69 of the communicating passage forming member 67 are connected to each other. With the communicating passage forming member 67 attached between the first shaft portion 41 and the partition wall portion 16 in this manner, the space 65 and the upper supply passage 75 are communicated with each other via the communicating holes 72 of the communicating passage forming member 67 and the inside of the tubular portion 69. That is, the communication passage 66 that connects the space 65 and the upper supply passage 75 is formed by the communication holes 72 of the communication passage forming member 67 and the inside of the cylindrical portion 69 .

[0063] In the outboard motor 1 of this embodiment, the cylindrical portion 69 of the communication passage forming member 67 has the function of forming the communication passage 66, as well as the function of forming a reduction gear cooling chamber 86, which will be described later.

[0064] 8, the upper supply passage 75 is a passage that connects the communication passage 66 and the cooling mechanism 85. The upper supply passage 75 is provided in the upper unit 2. The inlet end of the upper supply passage 75 is connected to the protruding portion 70 of the tubular portion 69 of the communication passage forming member 67. The outlet end of the upper supply passage 75 is connected to a heat exchanger 87 in the cooling mechanism 85. The upper supply passage 75 is formed, for example, by a hole formed in the right portion of the middle case 15 and a hose or pipe that connects the hole to the heat exchanger 87.

[0065] Water pump 77 is a pump that sends cooling water taken into lower unit 21 through water intake port 62 to cooling mechanism 85. Water pump 77 is, for example, a rotary variable-displacement water pump having a rubber impeller. Water pump 77 is disposed on the lower end side of first shaft portion 41. An impeller 78 of water pump 77 is disposed on the outer circumferential side of drive shaft 31. Impeller 78 is fixed to drive shaft 31 and rotates integrally therewith. A pump case 79 that houses impeller 78 is attached to, for example, the upper surface of lower case 27. Water pump 77 is covered by a steering case 29 provided at the top of lower case 27. The upper surface of pump case 79 faces space 65 between drive shaft 31 and first shaft portion 41. A discharge port 80 of water pump 77 opens to the upper surface of pump case 79 and communicates with space 65.

[0066] The discharge passage 81 is a passage that carries the cooling water that has flowed through the cooling mechanism 85 (heat exchanger 87) to a drain port 83. As can be seen from FIGS. 1 and 4, the discharge passage 81 connects the heat exchanger 87 and a discharge chamber 82 that is provided in the lower rear portion of the middle case 15. The discharge passage 81 is formed, for example, by a hose or a pipe.

[0067] The drain port 83 is an opening for discharging the cooling water to the outside of the outboard motor 1 after it has flowed through the cooling mechanism 85 (heat exchanger 87). The drain port 83 is provided in the lower part of the upper unit 2, rearward of the second shaft section 42. Specifically, the outboard motor 1 is provided with two drain ports 83. One of the drain ports 83 opens to the left side of the lower rear part of the middle case 15, and the other drain port 83 opens to the right side of the lower rear part of the middle case 15. Each of the drain ports 83 communicates with the inside of the discharge chamber 82. When the outboard motor 1 is viewed from the side, each of the drain ports 83 is located below the steering motor 45.

[0068] 7(A), the cooling mechanism 85 includes a reduction gear cooling chamber 86, a heat exchanger 87, a motor water jacket 88, an inverter water jacket 89, an electric pump 90, and a degassing tank 91. The cooling system 61 of the outboard motor 1 of this embodiment basically includes a direct cooling system in which water outside the outboard motor 1 is supplied to the heat exchanger 87 and the heat exchanger 87 uses the water to cool a refrigerant (e.g., a coolant such as LLC), and an indirect cooling system in which the refrigerant cooled by the heat exchanger 87 is supplied to the motor water jacket 88 and the inverter water jacket 89 and the motor water jacket 88 and the inverter water jacket 89 cool the drive motor 3 and the inverter 6. In the cooling system 61 of the outboard motor 1 of this embodiment, the reduction gear cooling chamber 86 is connected to the direct cooling system, and water outside the outboard motor 1 is supplied to the heat exchanger 87 via the reduction gear cooling chamber 86. The reduction gear 12 is cooled by the water outside the outboard motor 1 passing through the reduction gear cooling chamber 86.

[0069] The reduction gear cooling chamber 86 is a chamber that cools the reduction gear 12 using cooling water that is taken into the lower unit 21 from outside the outboard motor 1 through the water intake 62. The reduction gear cooling chamber 86 is provided below the reduction gear 12 in the upper unit 2. Specifically, as shown in FIG. 8 , the reduction gear cooling chamber 86 is formed in the middle case 15 between the bulkhead 16 that covers the reduction gear 12 from below and the tubular portion 69 of the communicating passage forming member 67 that is fixed to the bulkhead 16. As can be seen from FIG. 8 , part of the space formed inside the tubular portion 69 of the communicating passage forming member 67 corresponds to the reduction gear cooling chamber 86.

[0070] The heat exchanger 87 is a device that cools the refrigerant that cools the motor water jacket 88 and the inverter water jacket 89, using cooling water taken into the lower unit 21 from outside the outboard motor 1 through the water intake 62. As shown in FIG. 3 , the heat exchanger 87 is disposed in the upper unit 2 behind the drive motor 3 and attached to the drive motor 3.

[0071] The motor water jacket 88 is provided on the drive motor 3. The motor water jacket 88 is configured, for example, by a refrigerant flow path provided in the motor case 5. The refrigerant cooled by the heat exchanger 87 flows inside the motor water jacket 88, i.e., inside the flow path that constitutes the motor water jacket 88, thereby cooling the drive motor 3.

[0072] The inverter water jacket 89 is provided in the inverter 6. The inverter water jacket 89 is configured by a refrigerant flow path provided in, for example, the inverter case 8. The refrigerant that has flowed through the motor water jacket 88 flows through the inverter water jacket 89, i.e., the flow path that constitutes the inverter water jacket 89, thereby cooling the inverter main body 7.

[0073] The electric pump 90 is a pump that circulates the refrigerant in the heat exchanger 87, the motor water jacket 88, and the inverter water jacket 89. The electric pump 90 is disposed behind the inverter 6 in the upper unit 2 and is attached to the inverter 6.

[0074] The degassing tank 91 has the function of releasing bubbles generated in the refrigerant due to heat, etc., and the function of acting as a reserve tank to absorb increases or decreases in the amount of refrigerant due to thermal expansion or aging of the refrigerant. The degassing tank 91 is attached to the inverter 6 via multiple degassing tank mounting parts 9 provided on the inverter case 8. Each degassing tank mounting part 9 protrudes upward from the top surface of the inverter case 8.

[0075] As shown in FIG. 1 , the cooling mechanism 85 is also provided with a connection passage 93 that connects the heat exchanger 87 and the motor water jacket 88 and supplies refrigerant from the heat exchanger 87 to the motor water jacket 88. The connection passage 93 is formed, for example, by a hose or a pipe, and is located on the left side of the rear of the upper unit 2. The cooling mechanism 85 is also provided with a connection passage 94 that connects the motor water jacket 88 and the inverter water jacket 89 and sends refrigerant from the motor water jacket 88 to the inverter water jacket 89. The connection passage 94 is formed, for example, by a hose or a pipe, and is located on the upper left side of the rear of the upper unit 2. As shown in FIG. 2 , the cooling mechanism 85 is also provided with a connection passage 95 that connects the inverter water jacket 89 and the electric pump 90 and sends refrigerant from the inverter water jacket 89 to the electric pump 90. The connection passage 95 is formed, for example, by a hose or a pipe, and is located on the upper right side of the rear of the upper unit 2. The cooling mechanism 85 also has a connection passage 96 that connects the electric pump 90 and the heat exchanger 87 and sends refrigerant from the electric pump 90 to the heat exchanger 87. The connection passage 96 is formed, for example, by a hose or a pipe, and is located in the upper unit 2 in a section from behind the inverter 6 to behind the drive motor 3. The cooling mechanism 85 also has a connection passage 97 that connects the electric pump 90 and the degassing tank. The connection passage 97 is formed, for example, by a hose or a pipe, and is located on the upper right side of the rear part of the upper unit 2.

[0076] As shown in FIG. 8 , in the direct cooling system of the cooling device 61, when the water pump 77 is driven in response to rotation of the drive shaft 31, water outside the outboard motor 1 is taken into the lower unit 21 through the water intake 62. This water flows through the lower supply passage 64 and is drawn into the water pump 77 via its suction port. The drawn cooling water is then discharged from the water pump 77's discharge port 80 into the space 65 between the drive shaft 31 and the first shaft portion 41. The discharged cooling water flows through the space 65 and then through the communicating passage 66. Specifically, the communicating passage 66 is formed by the communicating hole 72 of the communicating passage-forming member 67 and the inside of the cylindrical portion 69. After flowing through the space 65, the cooling water first flows through the communicating hole 72 and then through the inside of the cylindrical portion 69. As described above, a portion of the space inside the cylindrical portion 69 of the communicating passage forming member 67 serves as the reduction gear cooling chamber 86. The reduction gear 12 is cooled by the cooling water flowing inside the cylindrical portion 69, i.e., the cooling water flowing inside the reduction gear cooling chamber 86. Subsequently, the cooling water after flowing inside the cylindrical portion 69 of the communicating passage forming member 67 flows into the upper supply passage 75. The cooling water that has flowed into the upper supply passage 75 flows through the upper supply passage 75 and into the heat exchanger 87 of the cooling mechanism 85. The cooling water that has flowed into the heat exchanger 87 also flows through the heat exchanger 87. This cools the refrigerant in the indirect cooling system. After flowing through the heat exchanger 87, the cooling water flows through the discharge passage 81, into the discharge chamber 82, and is discharged to the outside of the outboard motor 1 through the drain port 83.

[0077] In the indirect cooling system of the cooling device 61, when the electric pump 90 is driven, the refrigerant cooled by the heat exchanger 87 first flows through the motor water jacket 88. This cools the drive motor 3. After flowing through the motor water jacket 88, the refrigerant flows through the inverter water jacket 89. This cools the inverter main body 7. Next, the refrigerant, whose temperature has risen due to the heat of the drive motor 3 and the inverter main body 7, is sent through the electric pump 90 into the heat exchanger 87, where it is cooled.

[0078] As described above, in the cooling device 61 provided in the outboard motor 1 according to the embodiment of the present invention, part of the supply passage that supplies cooling water from the lower unit 21 to the upper unit 2 is formed by the space 65 between the drive shaft 31 and the first shaft portion 41. This configuration shortens the supply passage, thereby reducing pressure loss caused by the cooling water flowing through the supply passage. This therefore facilitates the supply of cooling water from the lower unit 21 to the upper unit 2.

[0079] Specifically, by forming a portion of the supply passage in the cooling device 61 provided in the outboard motor 1 of this embodiment using a space 65 between the drive shaft 31 and the first inner shaft portion 41 of the two shaft portions 41, 42 of the connecting mechanism 40, the portion of the supply passage can be made shorter than both the annular flow passage 1316 provided in the outboard motor 1020 shown in Figures 10(A) to 10(C) and the annular flow passage (annular channel 316) in the outboard motor described in Patent Document 1. In other words, the circumferential length of the annular space 65 existing between the drive shaft 31 and the first inner shaft portion 41 of the two shaft portions 41, 42 of the connecting mechanism 40 is longer than the outer circumferential length of the drive shaft 31 and shorter than the inner circumferential length of the first shaft portion 41. On the other hand, the circumferential length of the circle described by the annular flow passage 1316 in the outboard motor 1020 shown in Figures 10(A) to 10(C) is equivalent to the circumferential length of the center column 1035, which is located further outward from the steering column 1046, which is located outward from the drive shaft 1024. Therefore, if the size of the connecting mechanism 40 in the outboard motor 1 of this embodiment and the size of the connecting mechanism in the outboard motor 1020 are equal to each other, for example, if the inner diameter of the first shaft 41 in the outboard motor 1 of this embodiment and the inner diameter of the steering column 1046 in the outboard motor 1020 are equal to each other, and the outer diameter of the second shaft 42 in the outboard motor 1 of this embodiment and the outer diameter of the center column 1035 in the outboard motor 1020 are equal to each other, then the circumferential length of the annular space 65 existing between the drive shaft 31 and the first shaft 41 in the outboard motor 1 of this embodiment will be shorter than the circumferential length of the circle described by the annular flow path 1316 in the outboard motor 1020. Furthermore, if the size of the connecting mechanism 40 in the outboard motor of this embodiment is equal to the size of the connecting mechanism in the outboard motor described in Patent Document 1, the circumferential length of the annular space 65 existing between the drive shaft 31 and the first shaft portion 41 in the outboard motor 1 of this embodiment will be shorter than the circumferential length of the circle described by the annular channel 316 in the outboard motor described in Patent Document 1.Therefore, in the outboard motor 1 of this embodiment, a portion of the supply passage is formed by the annular space 65 existing between the drive shaft 31 and the first shaft portion 41, so that the portion of the supply passage can be made shorter than both the annular flow passage 1316 in the outboard motor 1020 and the annular flow passage (annular channel 316) in the outboard motor described in Patent Document 1. This reduces pressure loss caused by the cooling water flowing through the portion of the supply passage. This allows the cooling water taken in by the lower unit 21 to be smoothly supplied to the cooling mechanism 85 provided in the upper unit 2.

[0080] The cooling device 61 provided in the outboard motor 1 of this embodiment also includes a communication passage 66 that connects the space 65 and the upper supply passage 75, and a communication passage forming member 67 that forms the communication passage 66 is provided at the upper opening of the first shaft portion 41. By providing the communication passage forming member 67 at the upper opening of the first shaft portion 41, it is possible to prevent the connection between the space 65 and the upper supply passage 75 from being interrupted when the lower unit 21 rotates relative to the upper unit 2, or to prevent the flow of cooling water between the space 65 and the upper supply passage 75 from becoming poor. Specifically, the communicating passage forming member 67 includes a lid portion 68 attached to the upper opening of the first shaft portion 41, a tubular portion 69 extending upward from the outer periphery of the lid portion 68 and covering the opening on the inlet end side of the upper supply passage 75, and a communicating hole 72 provided on the inner periphery of the lid portion 68 to communicate between the space 65 and the inside of the tubular portion 69, the tubular portion 69 being fixed to the upper unit 2, and the lid portion 68 being inserted into the first shaft portion 41 so as to be rotatable relative to the first shaft portion 41. When the lower unit 21 rotates relative to the upper unit 2, the communicating passage forming member 67 having this configuration rotates relative to the first shaft portion 41 while maintaining communication between the space 65 and the upper supply passage 75 via the communicating hole 72 and the inside of the tubular portion 69. Therefore, when the lower unit 21 rotates relative to the upper unit 2, the connection between the space 65 and the upper supply passage 75 is not interrupted, and the flow of cooling water between the space 65 and the upper supply passage 75 is not impaired.

[0081] Furthermore, in the outboard motor 1 of this embodiment, a seal member 73 is provided between the outer periphery of the lid portion 68 of the communicating passage forming member 67 and the inner periphery of the first shaft portion 41. This prevents the cooling water that has flowed into the space between the drive shaft 31 and the first shaft portion 41 from leaking out of the supply passage within the upper unit 2 (specifically, within the middle case 15).

[0082] In the cooling device 61 provided in the outboard motor 1 of this embodiment, the water pump 77 that sends cooling water to the cooling mechanism 85 is disposed on the lower end side of the first shaft portion 41. This allows the discharge port 80 of the water pump 77 to be disposed below the space 65 between the drive shaft 31 and the first shaft portion 41, facing the space 65. This allows the cooling water to flow directly from the water pump 77 into the space 65. This allows the cooling water to be smoothly supplied to the cooling mechanism 85.

[0083] In the cooling system 61 provided in the outboard motor 1 of this embodiment, the water pump 77 is a rotary variable-volume water pump with a rubber impeller, and the impeller 78 of the water pump 77 is fixed to the drive shaft 31 and rotates integrally therewith. A rotary variable-volume water pump with a rubber impeller has self-priming capability and a high discharge pressure. Therefore, using a rotary variable-volume water pump with a rubber impeller as the water pump 77 eliminates the need for priming and stabilizes the supply of cooling water to the cooling mechanism 85. The outboard motor 1 can reverse the boat without reversing the drive motor 3 by rotating the lower unit 21 180 degrees relative to the upper unit 2. Therefore, the outboard motor 1 does not experience problems such as deterioration of the impeller 78 due to changes in the rotation direction of the impeller 78 when the boat is switched between forward and reverse. That is, a rubber impeller deteriorates significantly when its rotational direction changes. In an outboard motor that switches the boat's forward and reverse modes by changing the rotational direction of the drive motor, if the water pump's rubber impeller is fixed to the drive shaft and rotates integrally with the drive shaft, the rotational direction of the drive shaft changes each time the boat switches between forward and reverse, which in turn changes the rotational direction of the impeller, resulting in significant impeller deterioration. In contrast, the outboard motor 1 of this embodiment can reverse the boat without reversing the drive motor 3 by simply rotating the lower unit 21 180 degrees relative to the upper unit 2. Therefore, switching the boat between forward and reverse modes does not change the rotational direction of the drive shaft 31, and therefore the rotational direction of the impeller 78. Therefore, in the outboard motor 1, deterioration of the impeller 78 due to changes in its rotational direction does not occur.

[0084] 4, the outboard motor 1 of this embodiment is configured so that the large-diameter worm wheel 53 covers the entire upper opening of the second shaft portion 42. This configuration prevents the cooling water from splashing and flowing toward the bearing 43, even if the cooling water flowing through the supply passage leaks out of the supply passage inside the middle case 15.

[0085] The outboard motor 1 of this embodiment also includes a drain port 83 that discharges the cooling water after flowing through the cooling mechanism 85 to the outside of the outboard motor 1. The drain port 83 is located in the lower part of the upper unit 2, behind the second shaft 42. By providing the drain port 83 in the upper unit 2, a passage connecting the cooling mechanism 85 to the drain port 83 can be easily provided in an outboard motor 1 having a structure in which the lower unit 21 rotates relative to the upper unit 2. Furthermore, by locating the drain port 83 in the lower part of the upper unit 2, behind the second shaft 42, the drain port 83 can be positioned closer to the water surface outside the outboard motor 1. This reduces drain noise. In other words, the noise generated by the cooling water discharged from the drain port 83 and flowing down into the water outside the outboard motor 1 can be reduced.

[0086] The outboard motor 1 of the above embodiment is provided with a cooling device 61 shown in FIG. 7(A). However, the cooling device for the outboard motor of the present invention is not limited to the cooling device 61. For example, the outboard motor of the present invention may be provided with a cooling device 101 shown in FIG. 7(B) or a cooling device 103 shown in FIG. 7(C) instead of the cooling device 61. In the cooling mechanism 102 of the cooling device 101 shown in FIG. 7(B), the flow direction of the refrigerant through the heat exchanger 87, motor water jacket 88, and inverter water jacket 89 is opposite to that of the cooling mechanism 85 of the cooling device 61 shown in FIG. 7(A). Furthermore, the cooling device 103 shown in FIG. 7(C) does not have a configuration that includes both a direct cooling system and an indirect cooling system. The cooling mechanism 104 of the cooling device 103 is configured so that cooling water taken into the lower unit 21 from the water intake 62 is supplied to the reduction gear cooling chamber 86, the motor water jacket 88 and the inverter water jacket 89, thereby cooling the reduction gear 12, the drive motor 3 and the inverter 6.

[0087] Furthermore, the components cooled by the cooling device of the outboard motor of the present invention are not limited to the reduction gear, motor, and inverter. For example, the cooling device may be configured to cool only the motor, or only the motor and inverter, or components other than the reduction gear, motor, and inverter.

[0088] Furthermore, in the connecting mechanism for the outboard motor 1 in the above embodiment, the first shaft 41 provided on the lower unit 21 is inserted inside the second shaft 42 provided on the upper unit 2, but the connecting mechanism for the outboard motor of the present invention is not limited to this. The connecting mechanism for the outboard motor of the present invention may also be configured so that the second shaft provided on the upper unit is inserted inside the first shaft provided on the lower unit.

[0089] Furthermore, the present invention may be modified as appropriate within the scope of the claims and the spirit or concept of the invention as can be read from the entire specification, and outboard motors incorporating such modifications are also included within the technical concept of the present invention. [Explanation of symbols]

[0090] 1 outboard motor 2 Upper unit 3 Drive motor 21 Lower unit 23 Propeller shaft 31 Drive shaft 40 Connection mechanism 41 First shaft 42 Second shaft 61, 101, 103 Cooling device 62 Water Intake 64 Lower supply passage 65 Space 66 Communication path 67 Communication passage forming member 68 Lid 69 Cylinder part 71 Shaft insertion hole 72 Communication hole 73 Sealing material 75 Upper supply passage 77 Water Pump 78 Impeller 83 Drain 85, 102, 104 Cooling mechanism

Claims

1. an upper unit including a drive motor; a lower unit including a propeller shaft; a drive shaft that transmits rotation of the drive motor to the propeller shaft; a connecting mechanism that connects the lower unit to the upper unit so as to be rotatable about the axis of the drive shaft; and a cooling device, The cooling device is a cooling mechanism provided in the upper unit for cooling devices including the drive motor using cooling water; a water intake port for taking water from outside the outboard motor into the lower unit as cooling water; a supply passage extending from the lower unit to the upper unit, for supplying the cooling water taken into the lower unit to the cooling mechanism; The connecting mechanism includes: a cylindrical first shaft portion provided on an upper portion of the lower unit and having an axis coaxial with an axis of the drive shaft; a cylindrical second shaft portion provided at a lower portion of the upper unit and having an axis coaxial with an axis of the drive shaft, an outboard motor, wherein one of the first shaft portion and the second shaft portion is inserted inside the other shaft portion so as to be rotatable relative to the other shaft portion, the drive shaft is inserted inside the one shaft portion via a space, and a portion of the supply passage is formed by the space between the drive shaft and the one shaft portion.

2. the one shaft portion is the first shaft portion, The supply passage is a lower supply passage provided in the lower unit and connecting the water intake and the space; The space; an upper supply passage provided in the upper unit, one end of which is connected to the cooling mechanism; a communication passage that communicates between the space and the other end of the upper supply passage, 2. An outboard motor according to claim 1, wherein a communication passage forming member that forms the communication passage is provided at an upper opening of the first shaft portion.

3. The communication passage forming member is a cover attached to an upper opening of the first shaft; a cylindrical portion extending upward from the outer periphery of the lid portion and covering an opening on the other end side of the upper supply passage; a shaft insertion hole provided in a center portion of the lid portion, into which the drive shaft is inserted; 3. The outboard motor according to claim 2, further comprising a communication hole provided on an inner periphery of the lid portion for communicating between the space and the inside of the cylindrical portion.

4. 4. The outboard motor according to claim 3, wherein the cylindrical portion is fixed to the upper unit, and the lid portion is inserted into the first shaft portion so as to be rotatable relative to the first shaft portion.

5. 5. An outboard motor according to claim 4, wherein a seal member is provided between an outer periphery of the cover portion and an inner periphery of the first shaft portion.

6. 2. The outboard motor according to claim 1, wherein the cooling device includes a water pump that sends cooling water taken into the lower unit to the cooling mechanism, the water pump being disposed on the lower end side of the first shaft portion.

7. 2. The outboard motor according to claim 1, wherein the cooling device includes a water pump that sends cooling water taken into the lower unit to the cooling mechanism, the water pump being a rotary variable displacement water pump having a rubber impeller, the impeller being fixed to the drive shaft and rotating integrally with the drive shaft.

8. 2. The outboard motor according to claim 1, wherein the cooling device includes a drain port that discharges the cooling water after flowing through the cooling mechanism to outside the outboard motor, the drain port being provided in a lower portion of the upper unit and rearward of the second shaft portion.

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