Propulsion device for water-surface movable body

Abstract

To provide a propulsion device for a water-surface movable body, capable of meeting a demand for lowering a top of the same by reducing an overall height of the same.SOLUTION: A propulsion device for a water-surface movable body includes: a lower case 13 supported by an upper case 11 so as to be turnable around a turning axis X1; a steering motor 19 accommodated in the upper case 11; and a steering deceleration mechanism 20 for decelerating rotation of the steering motor 19. The steering deceleration mechanism 20 includes: an output shaft gear 125 arranged coaxially with an output shaft 118 of the steering motor 19; a ring gear 126 arranged coaxially with the turning axis X1; and a plurality of deceleration gears 131-136 interposed between the output shaft gear 125 and the ring gear 126 on a steering force transmission path R2. At least one of the plurality of deceleration gears 131-136 is located above the output shaft gear 125 in a state where the turning axis X1 extends in a vertical direction.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a propulsion device for a water vehicle. [Background technology]

[0002] In recent years, efforts to realize a low-carbon or carbon-free society have become more active, and research and development into electrification technologies is being conducted to reduce CO2 emissions and improve energy efficiency in propulsion devices for water vehicles such as outboard motors.

[0003] For example, Patent Document 1 discloses a propulsion device (ship propulsion device) for a water vehicle that includes a propeller (propulsion unit), a steering motor (control motor) that rotates the propeller around a vertical axis, and a steering reduction mechanism (control transmission) that slows down the rotation of the steering motor. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] U.S. Patent No. 8,550,948 Summary of the Invention [Problem to be solved by the invention]

[0005] In Patent Document 1, the steering reduction mechanism is configured with a planetary gear mechanism and is arranged vertically stacked with the steering motor, which increases the overall height of the waterborne vehicle propulsion device, potentially making it impossible to meet the demand for a low-profile propulsion device for waterborne vehicles.

[0006] In view of the above background, an object of the present invention is to provide a propulsion device for a water vehicle that can meet the demand for a low headroom by reducing the overall height, and which will ultimately contribute to improving energy efficiency. [Means for solving the problem]

[0007] In order to solve the above-mentioned problems, one aspect of the present invention is a propulsion device (1, 201) for a water vehicle, comprising: an upper case (11) supported by a hull (4) of a water vehicle (3); a propulsion motor (12) housed in the upper case; a lower case (13) rotatably supported by the upper case around a rotation axis (X1); a propeller (14) supported by the lower case and rotated around a propulsion axis (X2) by the driving force of the propulsion motor; a steering motor (19) housed in the upper case; and a steering reduction mechanism (20, 203) provided in a steering force transmission path (R2) from the steering motor to the lower case, for reducing the rotation speed of the steering motor. , and the steering reduction mechanism has at least one gear shaft (121-123, 211-214) arranged parallel to the output shaft (118) of the steering motor, an output shaft gear (125, 215) arranged coaxially with the output shaft of the steering motor, a ring gear (126, 216) arranged coaxially with the rotating shaft, and a plurality of reduction gears (131-136, 221-228) provided on the at least one gear shaft and interposed between the output shaft gear and the ring gear in the steering force transmission path, and at least one of the plurality of reduction gears is located above the output shaft gear when the rotating shaft extends vertically.

[0008] According to this aspect, the steering reduction mechanism is configured with a parallel shaft gear train, and at least one of the multiple reduction gears is located above the output shaft gear. Therefore, compared to a case in which the steering reduction mechanism is configured with a planetary gear mechanism and is arranged above and below the steering motor, the overall height of the water vehicle propulsion device is lower, allowing the water vehicle propulsion device to have a lower profile.

[0009] In the above aspect, the at least one gear shaft may be located within a width (W1) in the left-right direction of the ring gear in a plan view.

[0010] According to this aspect, the width of the propulsion device for a surface vehicle can be reduced in the left-right direction. This, combined with the lowering of the head of the propulsion device, allows the entire propulsion device for a surface vehicle to be made smaller. This not only reduces the weight of the propulsion device for a surface vehicle, but also allows for more suitable placement of multiple propulsion devices on a hull. It also reduces the propulsion resistance of the surface vehicle.

[0011] In the above aspect, the outline of the steering motor may be located within a width (W1) of the ring gear in the left-right direction in a plan view.

[0012] According to this aspect, the steering motor, which is a heavy object, is positioned within the left-right width of the ring gear, thereby improving the left-right weight balance of the water vehicle propulsion device.

[0013] In the above aspect, the output shaft and the rotation shaft of the steering motor may be arranged on the same straight line (Y) extending in the front-rear direction.

[0014] According to this aspect, the output shaft of the steering motor, which is a heavy object, and the rotary shaft are arranged on the same straight line extending in the fore-and-aft direction, thereby further improving the left-right weight balance of the water vehicle propulsion device.

[0015] In the above aspect, the propulsion device for the water vehicle may further include a brake mechanism (21) that restricts the rotation of the lower case, and the outline of the brake mechanism may be located within the left-right width (W1) of the ring gear when viewed in a plane.

[0016] According to this aspect, the brake mechanism, which is a heavy object, is positioned within the left-right width of the ring gear, thereby improving the left-right weight balance of the water vehicle propulsion device.

[0017] In the above aspect, the propulsion device for the water vehicle may further include a separator (27) that divides the internal space of the upper case into an oil chamber (S1) and a dry chamber (S2), the steering motor has a motor body (117) housed in the dry chamber, and the multiple reduction gears may be housed in the oil chamber.

[0018] According to this aspect, the oil chamber and the dry chamber can be separated with a simple configuration. Also, by accommodating the multiple reduction gears in the oil chamber, the multiple reduction gears can be suitably lubricated and noise from the multiple reduction gears is less likely to be transmitted to the outside.

[0019] In the above aspect, the propulsion device for the water vehicle may further include a planetary reduction mechanism (17) that is provided in the driving force transmission path (R1) from the propulsion motor to the propeller and that reduces the rotation of the propulsion motor, the lower case may have a cylindrical rotating part (38) centered on the rotation axis, the planetary reduction mechanism may be arranged on the inner circumference of the rotating part, and the multiple reduction gears may be arranged at the same height as the rotating part.

[0020] According to this aspect, the parallel shaft gear train constituting the steering reduction mechanism can be arranged compactly in the height direction, thereby enabling the water vehicle propulsion device to have an even lower head.

[0021] In the above aspect, the plurality of reduction gears (131-136) may include a downstream end gear (136) that engages with the ring gear, and the downstream end gear may be located at the uppermost position among the plurality of reduction gears.

[0022] According to this aspect, the overall height of the waterborne vehicle propulsion device is further reduced, allowing the waterborne vehicle propulsion device to be further lowered.

[0023] In the above aspect, the plurality of reduction gears (221-228) may include an upstream end gear (221) that engages with the output shaft gear, and the upstream end gear may be located at the lowest position among the plurality of reduction gears.

[0024] According to this aspect, the overall height of the waterborne vehicle propulsion device is further reduced, allowing the waterborne vehicle propulsion device to be further lowered. [Effects of the Invention]

[0025] According to the above aspect, it is possible to provide a propulsion device for an underwater vehicle that can meet the demand for a low headroom by reducing the overall height. [Brief explanation of the drawings]

[0026] [Figure 1] FIG. 1 is a side view showing an outboard motor according to a first embodiment of the present invention; [Figure 2] FIG. 1 is a cross-sectional view showing an outboard motor according to a first embodiment of the present invention; [Figure 3] 1 is a cross-sectional view showing a steering reduction mechanism and its surroundings according to a first embodiment; [Figure 4] 1 is a cross-sectional view showing a rotating portion and its surroundings according to a first embodiment; [Figure 5] FIG. 1 is a cross-sectional view showing a gear case and its surroundings according to a first embodiment. [Figure 6] FIG. 1 is a plan view showing a steering reduction mechanism and its peripheral parts according to a first embodiment; [Figure 7] FIG. 1 is a cross-sectional view showing a state in which a manual rotation member according to a first embodiment is in a first position; [Figure 8] FIG. 10 is a cross-sectional view showing a state in which the manual rotation member according to the first embodiment is in a second position. [Figure 9] 1 is a cross-sectional view showing a rotation angle detection mechanism and its surroundings according to a first embodiment; [Figure 10] FIG. 1 is a perspective view showing a rotation angle detection mechanism and its surroundings according to a first embodiment; [Figure 11] FIG. 10 is a cross-sectional view showing a steering reduction mechanism and its peripheral parts according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0027] (First embodiment) An outboard motor 1 (an example of a water vehicle propulsion device) according to one embodiment of the present invention will now be described with reference to the drawings. The arrow Fr in each drawing indicates the front of the outboard motor 1. Hereinafter, the term "coupled" refers to a state in which multiple members are engaged together so that they cannot rotate relative to each other.

[0028] As shown in Figure 1, an outboard motor 1 is disposed outside a hull 4 of a vessel 3 (an example of a watercraft) such as a boat. The outboard motor 1 is attached to the rear end of the hull 4 via a mounting device 5. The mounting device 5 includes a bracket 7 that supports the outboard motor 1 via a tilt shaft 6 extending in the left-right direction, and a clamp device 8 that detachably secures the bracket 7 to the rear end of the hull 4. The outboard motor 1 is tiltable about the tilt shaft 6 by a hydraulic or electric actuator 9.

[0029] 1 and 2, the outboard motor 1 includes an upper case 11 supported on a hull 4 of a boat 3 via a mounting device 5, a propulsion motor 12 housed in the upper case 11, a lower case 13 rotatably supported on the upper case 11 about a rotation axis X1, a propeller 14 supported on the lower case 13 and rotated about a propeller axis X2 by the driving force of the propulsion motor 12, a drive shaft 15 provided on a driving force transmission path R1 from the propulsion motor 12 to the propeller 14 and extending along the rotation axis X1, and a bevel gear mechanism 16 housed in the lower case 13 and connecting the drive shaft 15 to the propeller 14. The outboard motor 1 includes a planetary reduction mechanism 17 that is provided in the drive force transmission path R1 and that reduces the rotation speed of the propulsion motor 12, an oil pump 18 (an example of a coolant supply mechanism) that supplies cooling oil (an example of a coolant) to the planetary reduction mechanism 17, a steering motor 19 housed in the upper case 11, a steering reduction mechanism 20 that is provided in the steering force transmission path R2 that extends from the steering motor 19 to the lower case 13 and that reduces the rotation speed of the steering motor 19, a brake mechanism 21 that restricts the rotation of the lower case 13, and a rotation angle detection mechanism 22 that detects the rotation angle of the lower case 13 relative to the upper case 11. Below, the components of the outboard motor 1 will be described based on a state in which the rotation axis X1 extends vertically and the propulsion shaft X2 extends in the fore-and-aft direction (see FIG. 2).

[0030] <Upper case 11> Referring to FIG. 3, the upper case 11 has an upper wall 25, a lower wall 26 disposed below the upper wall 25, and a separator 27 disposed between the upper wall 25 and the lower wall 26. A communication hole 31 is provided in the center of the upper wall 25 in the front-to-rear direction, connecting the internal space of the upper case 11 with the external space. The communication hole 31 is closed by a removable plug 32. The separator 27 divides the internal space of the upper case 11 into an oil chamber S1 and a dry chamber S2. The oil chamber S1 is located below the separator 27 and contains cooling oil. The dry chamber S2 is located above the separator 27 and does not contain cooling oil. An upwardly protruding boss 33 is provided in the center of the separator 27 in the front-to-rear direction.

[0031] <Propulsion Motor 12> 2, the propulsion motor 12 is housed in the upper front part of the upper case 11. The propulsion motor 12 is an electric motor. The propulsion motor 12 has a motor body 35 and a motor shaft 36 that extends downward from the motor body 35.

[0032] <Lower Case 13> 4 and 5, the lower case 13 has a rotating portion 38 and a case main body 39 disposed below the rotating portion 38.

[0033] 4, the rotating part 38 has a cylindrical shape centered on a rotation axis X1. The rotating part 38, excluding its lower end, is housed in the upper case 11. An annular protrusion 41 is provided on the inner peripheral surface of the lower part of the rotating part 38. Hereinafter, the part of the internal space of the rotating part 38 above the annular protrusion 41 will be referred to as the "rotation space 42."

[0034] An upper bearing 44 is disposed on the outer periphery of the upper part of the rotating part 38. The upper bearing 44 is attached to the separator 27 of the upper case 11. A lower bearing 45 is disposed on the outer periphery of the lower part of the rotating part 38. The lower bearing 45 is attached to the bottom wall 26 of the upper case 11. With this configuration, the lower case 13 is rotatably supported by the upper case 11 via the upper bearing 44 and the lower bearing 45. An annular expanded diameter part 46 is provided at the upper end of the rotating part 38. The expanded diameter part 46 expands in diameter above the upper bearing 44.

[0035] 5, a first bearing recess 48 is provided in the case body 39 below the rotating part 38. The first bearing recess 48 communicates with the rotating space 42 via an axial passage 49 extending in the vertical direction along the rotation axis X1. A first bearing 50 is fitted into the first bearing recess 48.

[0036] A first heat exchange chamber 52 is provided in the case body 39, below and in front of the first bearing recess 48. An upper portion of the first heat exchange chamber 52 communicates with the first bearing recess 48 via a first communication passage 53 that extends downward and forward.

[0037] A second heat exchange chamber 55 is provided in the case body 39 in front of and above the first heat exchange chamber 52. The second heat exchange chamber 55, together with the first heat exchange chamber 52, constitutes a heat exchange section 56 with the cooling oil. A lower portion of the second heat exchange chamber 55 communicates with the lower portion of the first heat exchange chamber 52 via a second communication passage 57 extending downward and forward. An upper portion of the second heat exchange chamber 55 is separated from the upper portion of the first heat exchange chamber 52 by a partition member 58. An oil filter 59 (an example of a filter member) that filters the cooling oil is housed in the upper portion of the second heat exchange chamber 55. The oil filter 59 is supported from below by the partition member 58. An upper portion of the second heat exchange chamber 55 communicates with the rotation space 42 via a third communication passage 60 extending vertically in front of the axial passage 49.

[0038] The rotation space 42, the shaft passage 49, the first bearing recess 48, the first communication passage 53, the first heat exchange chamber 52, the second communication passage 57, the second heat exchange chamber 55, and the third communication passage 60 constitute a first passage P1 for cooling oil. The upper part of the first passage P1 is located at the same height as the lower part of the upper case 11. The height of the liquid surface of the cooling oil contained in the first passage P1 is set, for example, below the planetary reduction mechanism 17 (see FIG. 4, etc.) and above the oil pump 18. Note that the dashed arrows in FIG. 5 indicate the flow of cooling oil within the first passage P1.

[0039] A bullet-shaped gear case 62 extending in the front-rear direction is provided at the bottom of the case main body 39. A first outlet 63 for discharging cooling oil from the first passage P1 is provided at the front surface of the gear case 62. The first outlet 63 opens toward the front. The first outlet 63 communicates with the lower end of the second heat exchange chamber 55 via a first outlet passage 64 that slopes downward toward the front. The first outlet 63 is closed by a removable first cap (not shown).

[0040] A second bearing recess 66 is provided in the gear case 62 of the case body 39 below the first bearing recess 48. A second bearing 67 is fitted in the second bearing recess 66. The second bearing 67 is disposed below the first bearing 50.

[0041] A bevel gear chamber 69 is provided in the gear case 62 of the case body 39 below the second bearing recess 66. The bevel gear chamber 69 is in direct communication with the second bearing recess 66. The bevel gear chamber 69 houses a bevel gear mechanism 16 (details of which will be described later). The bevel gear mechanism 16 is disposed below the second bearing 67.

[0042] A third heat exchange chamber 71 is provided in the case body 39 above and rearward of the second bearing recess 66 and the bevel gear chamber 69. The third heat exchange chamber 71 communicates with the second bearing recess 66 via a fourth communication passage 72 that extends upward toward the rear. The third heat exchange chamber 71 communicates with the bevel gear chamber 69 via a fifth communication passage 73 that extends upward toward the rear.

[0043] The bevel gear chamber 69, the second bearing recess 66, the fourth communication passage 72, the third heat exchange chamber 71, and the fifth communication passage 73 constitute a second cooling oil passage P2. The second passage P2 is separated from the first passage P1 by a seal member 74 disposed between the first bearing 50 and the second bearing 67. The entire second passage P2 is located below the upper case 11. The liquid level of the cooling oil contained in the second passage P2 is set, for example, below the second bearing 67 and above the bevel gear mechanism 16. The type of cooling oil contained in the second passage P2 is different from the type of cooling oil contained in the first passage P1. For example, the viscosity of the cooling oil contained in the second passage P2 is higher than the viscosity of the cooling oil contained in the first passage P1.

[0044] A second outlet 76 for discharging cooling oil from the second passage P2 is provided on the front surface of the gear case 62 of the case body 39. The second outlet 76 is disposed lower than the first outlet 63. The second outlet 76 opens toward the front. The second outlet 76 communicates with the front end of the bevel gear chamber 69 via a second outlet passage 77 that slopes downward toward the front. The second outlet 76 is closed by a removable second cap (not shown).

[0045] <Propulsion unit 14> 2, the propeller 14 is rotatable about a rotation axis X1 integrally with the lower case 13, and is rotatable about a propeller axis X2 relative to the lower case 13. The propeller 14 has a propeller shaft 91 extending along the propeller axis X2, and a propeller 92 fixed to a rear portion of the propeller shaft 91. A front portion of the propeller shaft 91 is rotatably supported by a gear case 62 of the lower case 13.

[0046] <Drive shaft 15> 2, the drive shaft 15 extends in the vertical direction and has an upper shaft 94 and a lower shaft 95 disposed below the upper shaft 94 and coaxially with the upper shaft 94.

[0047] The upper portion of the upper shaft 94 is rotatably supported on the upper wall 25 of the upper case 11. The upper end portion of the upper shaft 94 is fixed to the motor shaft 36 of the propulsion motor 12. This allows the upper shaft 94 to rotate integrally with the motor shaft 36 of the propulsion motor 12.

[0048] 4, the lower part of the upper shaft 94 is inserted into the upper part of the lower shaft 95 so as to be rotatable relative to the upper part. The lower part of the upper shaft 94 is provided with an upper axial passage 99 extending in the up-down direction (axial direction), and a plurality of upper radial passages 100 extending radially from the upper axial passage 99 to the outer circumferential surface of the upper shaft 94.

[0049] A lower axial passage 102 extending in the up-down direction (axial direction), an annular groove 103 provided in the outer peripheral surface of the lower shaft 95, and a lower radial passage 104 extending radially from the lower axial passage 102 to the annular groove 103 are provided in the upper part of the lower shaft 95. The upper end of the lower axial passage 102 communicates with the lower end of the upper axial passage 99 of the upper shaft 94.

[0050] 5, the above-mentioned first bearing 50 is attached to the vertical center of the lower shaft 95. The above-mentioned second bearing 67 is attached to the lower part of the lower shaft 95. With this configuration, the lower shaft 95 is rotatably supported by the lower case 13 via the first bearing 50 and the second bearing 67.

[0051] <Bevel gear mechanism 16> 5, the bevel gear mechanism 16 has a first bevel gear 106 arranged coaxially with the rotation axis X1, and a second bevel gear 107 arranged coaxially with the propeller shaft X2 and engaged with the first bevel gear 106. The first bevel gear 106 is fixed to the lower end of the lower shaft 95 of the drive shaft 15 and is provided so as to be rotatable integrally with the lower shaft 95. The second bevel gear 107 is fixed to the front end of the propeller shaft 91 of the propeller 14 and is provided so as to be rotatable integrally with the propeller shaft 91.

[0052] <Planetary reduction mechanism 17> 4, the planetary reduction mechanism 17 is housed in the rotation space 42 of the rotation part 38 of the lower case 13. The planetary reduction mechanism 17 is disposed on the inner periphery of the expanded diameter part 46 of the rotation part 38. The planetary reduction mechanism 17 is configured by, for example, a planetary type planetary gear mechanism. In other embodiments, the planetary reduction mechanism 17 may be configured by a planetary gear mechanism other than a planetary type (for example, a solar type or star type planetary gear mechanism).

[0053] The planetary reduction mechanism 17 has a sun gear 109, a plurality of planet gears 110 that engage with the sun gear 109, a planet carrier 111 that rotatably supports the plurality of planet gears 110, and an internal gear 112 that engages with the plurality of planet gears 110. The sun gear 109 is coupled to the lower part of the upper shaft 94 and is provided so as to be rotatable integrally with the upper shaft 94. The planet carrier 111 is formed integrally with the upper end part of the lower shaft 95 and is provided so as to be rotatable integrally with the lower shaft 95.

[0054] <Oil pump 18> Referring to FIG. 4, the oil pump 18 is housed in the rotation space 42 of the rotation portion 38 of the lower case 13. The oil pump 18 is disposed on the inner periphery of the rotation portion 38 below the expanded diameter portion 46. The oil pump 18 is disposed below the planetary reduction mechanism 17. The oil pump 18 is disposed on the outer periphery of the lower shaft 95 of the drive shaft 15 and is configured to operate in conjunction with the rotation of the lower shaft 95. The oil pump 18 is configured, for example, by a trochoid pump. In other embodiments, the oil pump 18 may be configured by a mechanical pump other than a trochoid pump (for example, a screw pump) or may be configured by an electric pump.

[0055] An oil suction port 114 (an example of a coolant suction port) for drawing cooling oil into the oil pump 18 is provided at the bottom of the oil pump 18. The oil suction port 114 is formed in the rotating part 38 of the lower case 13 and is provided so as to be rotatable integrally with the rotating part 38. The oil suction port 114 is disposed forward of the rotation axis X1. The oil suction port 114 is disposed below the planetary reduction mechanism 17. The oil suction port 114 is in communication with the upper end of the third communication passage 60.

[0056] An oil discharge port 115 (an example of a coolant discharge port) for discharging cooling oil from the oil pump 18 is provided at the top of the oil pump 18. The oil discharge port 115 is formed in the rotating part 38 of the lower case 13 and is provided so as to be rotatable integrally with the rotating part 38. The oil discharge port 115 is located below the planetary reduction mechanism 17. The oil discharge port 115 communicates with the annular groove 103 of the lower shaft 95.

[0057] <Steering motor 19> 3 and 6, the steering motor 19 is housed in the rear of the upper case 11. The steering motor 19 is an electric motor. In a plan view, the outline of the steering motor 19 is located within a width W1 in the left-right direction of a ring gear 126 (details of which will be described later) of the steering reduction mechanism 20. In a plan view, the outline of the steering motor 19 is located within a width W2 in the left-right direction of the rotating portion 38 of the lower case 13.

[0058] The steering motor 19 has a motor body 117 and an output shaft 118 extending downward from the motor body 117. The motor body 117 is housed in the dry chamber S2 of the upper case 11. The output shaft 118 extends in the vertical direction. The output shaft 118 penetrates the separator 27 of the upper case 11 and extends to the oil chamber S1 of the upper case 11. The output shaft 118 and the rotation axis X1 are arranged on the same straight line Y that extends in the front-to-rear direction.

[0059] <Steering reduction mechanism 20> Hereinafter, in the description of the steering reduction mechanism 20, when the upstream side or downstream side is mentioned, it refers to the upstream side or downstream side of the steering force transmission path R2 from the steering motor 19 to the lower case 13.

[0060] 3, the steering reduction mechanism 20 is housed in the upper case 11. The steering reduction mechanism 20 is configured with a parallel shaft gear train. The steering reduction mechanism 20 has a plurality of gear shafts 121-123 arranged parallel to the output shaft 118 of the steering motor 19, a detent mechanism 124 engaged with one of the plurality of gear shafts 121-123 (more specifically, the third gear shaft 123 described later), an output shaft gear 125 arranged coaxially with the output shaft 118 of the steering motor 19, a ring gear 126 arranged coaxially with the rotation axis X1, and a plurality of reduction gears 131-136 provided on the plurality of gear shafts 121-123 and interposed between the output shaft gear 125 and the ring gear 126 in the steering force transmission path R2. Note that FIG. 3 is a cross-sectional view of a vertical cross section bent along the steering force transmission path R2. Therefore, the drive shaft 15, the output shaft 118 of the steering motor 19, and the plurality of gear shafts 121 to 123, which are not actually arranged on the same plane in space, are shown on the same plane in FIG.

[0061] 6, all of the gear shafts 121 to 123 are located within a width W1 in the left-right direction of the ring gear 126 in a plan view. All of the gear shafts 121 to 123 are located within a width W2 in the left-right direction of the rotating portion 38 of the lower case 13 in a plan view. The gear shafts 121 to 123 include a first gear shaft 121, a second gear shaft 122, and a third gear shaft 123. The gear shafts 121 to 123 are arranged in the order of first gear shaft 121, second gear shaft 122, and third gear shaft 123 from the upstream side to the downstream side.

[0062] 3, the first gear shaft 121 and the second gear shaft 122 extend in the vertical direction. The upper ends of the first gear shaft 121 and the second gear shaft 122 are rotatably supported by the separator 27 of the upper case 11. The lower ends of the first gear shaft 121 and the second gear shaft 122 are rotatably supported by the bottom wall 26 of the upper case 11.

[0063] The third gear shaft 123 has an upstream rotating member 138 to which the rotation of the output shaft 118 of the steering motor 19 is transmitted, a downstream rotating member 139 provided downstream of the upstream rotating member 138, and a manual rotating member 140 interposed between the upstream rotating member 138 and the downstream rotating member 139 in the steering force transmission path R2. The upstream rotating member 138, the downstream rotating member 139, and the manual rotating member 140 are arranged coaxially.

[0064] 7 and 8, the upstream rotating member 138 has a cylindrical shape extending in the vertical direction (axial direction). The upstream rotating member 138 is rotatably supported on the bottom wall 26 of the upper case 11. An annular upstream coupling portion 142 is provided on the inner circumferential surface of the lower part of the upstream rotating member 138. An annular fitting groove 143 is provided on the inner circumferential surface of the central and upper parts of the upstream rotating member 138 in the vertical direction. The vertical length of the fitting groove 143 is longer than the vertical length of the upstream coupling portion 142.

[0065] The downstream rotating member 139 has a cylindrical shape that extends in the vertical direction (axial direction). The upper end of the downstream rotating member 139 is rotatably supported by the separator 27 of the upper case 11. The lower part of the downstream rotating member 139 is fitted into a fitting groove 143 of the upstream rotating member 138 in a spigot-joint structure so as to be relatively rotatable. A downstream connecting portion 144 is provided on the inner circumferential surface of the lower part of the downstream rotating member 139, above the upstream connecting portion 142 of the upstream rotating member 138.

[0066] The manual rotation member 140 has a cylindrical shape extending in the vertical direction (axial direction). The upper end of the manual rotation member 140 is provided with a tool engagement portion 146 for engaging a rotary tool T (see FIG. 8). The upper portion of the manual rotation member 140 is rotatably supported on the upper wall 25 of the upper case 11. The upper portion of the manual rotation member 140 is inserted into the communication hole 31 of the upper wall 25. The lower end of the manual rotation member 140 is provided with a manual rotation shaft portion 147. The manual rotation shaft portion 147 is disposed on the inner peripheries of the upstream rotation member 138 and the downstream rotation member 139. The manual coupling portion 148 is provided on the outer periphery of the manual rotation shaft portion 147.

[0067] A first engagement recess 151 and a second engagement recess 152 are provided on the outer peripheral surface of the manual rotation member 140 at the center in the vertical direction. The first engagement recess 151 and the second engagement recess 152 are curved in an arc shape. The second engagement recess 152 is provided below the first engagement recess 151.

[0068] The manual rotation member 140 is provided so as to be movable in the vertical direction relative to the upstream rotation member 138 and the downstream rotation member 139. Specifically, the manual rotation member 140 is provided so as to be movable in the vertical direction between a first position (see FIG. 7) and a second position (see FIG. 8) that is shifted upward from the first position. When the manual rotation member 140 is in the first position, the manual coupling portion 148 is spline-coupled to the upstream coupling portion 142 and the downstream coupling portion 144. Therefore, rotation of the upstream rotation member 138 and the downstream rotation member 139 relative to the manual rotation member 140 is restricted. When the manual rotation member 140 is in the second position, the spline-coupled connection between the manual coupling portion 148 and the upstream coupling portion 142 is released, and the manual coupling portion 148 is spline-coupled to the downstream coupling portion 144. Therefore, rotation of the manual rotation member 140 relative to the upstream rotation member 138 is permitted, and rotation of the downstream rotation member 139 relative to the manual rotation member 140 is restricted.

[0069] 9, the detent mechanism 124 includes an engaging body 155 supported by a resolver holder 169 (details of which will be described later) of the rotation angle detection mechanism 22, and a biasing body 156 interposed between the resolver holder 169 and the engaging body 155. The engaging body 155 is provided so as to be movable in the horizontal direction (a direction perpendicular to the up-down direction) between an engaging position (see solid line in FIG. 9) where it engages with the first engaging recess 151 or the second engaging recess 152 of the manual rotation member 140, and a disengaging position (see chain double-dashed line in FIG. 9) where it disengages from the first engaging recess 151 and the second engaging recess 152. The biasing body 156 is formed of a compression coil spring. The biasing body 156 biases the engaging body 155 toward the engaging position.

[0070] 7, when the manual rotation member 140 is in the first position, the engaging body 155 is in the engaging position and is engaged with the first engaging recess 151 of the manual rotation member 140. This holds the manual rotation member 140 in the first position, and prevents the manual rotation member 140 from moving inadvertently from the first position to the second position. Referring to FIG. 8, when the manual rotation member 140 is in the second position, the engaging body 155 is in the engaging position and is engaged with the second engaging recess 152 of the manual rotation member 140. This holds the manual rotation member 140 in the second position, and prevents the manual rotation member 140 from moving inadvertently from the second position to the first position.

[0071] 3, the output shaft gear 125 is housed in the oil chamber S1 of the upper case 11. The output shaft gear 125 is coupled to the output shaft 118 of the steering motor 19 and is provided so as to be rotatable integrally with the output shaft 118 of the steering motor 19. The output shaft gear 125 is disposed directly below the motor body 117 of the steering motor 19. Note that the output shaft gear 125 may be formed integrally with the output shaft 118 of the steering motor 19.

[0072] The ring gear 126 is housed in the oil chamber S1 of the upper case 11. The ring gear 126 is coupled to the outer peripheral surface of the rotating part 38 of the lower case 13 between the upper bearing 44 and the lower bearing 45, and is provided so as to be rotatable integrally with the rotating part 38. The ring gear 126 is located above the output shaft gear 125. The ring gear 126 is disposed at approximately the same height as the oil pump 18.

[0073] All of the multiple reduction gears 131-136 are housed in the oil chamber S1 of the upper case 11. All of the multiple reduction gears 131-136 are disposed at the same height as the rotating portion 38 of the lower case 13. With reference to Fig. 6, all of the multiple reduction gears 131-136 are located within the width W1 in the left-right direction of the ring gear 126 in a plan view. Preferably, the outer diameters of the multiple reduction gears 131-136 are located within the width W1 in the left-right direction of the ring gear 126 in a plan view.

[0074] The multiple reduction gears 131-136 include a first reduction gear 131 (an example of an upstream end gear), a second reduction gear 132, a third reduction gear 133, a fourth reduction gear 134, a fifth reduction gear 135, and a sixth reduction gear 136 (an example of a downstream end gear). The multiple reduction gears 131-136 are arranged in the following order from the upstream side to the downstream side: first reduction gear 131, second reduction gear 132, third reduction gear 133, fourth reduction gear 134, fifth reduction gear 135, and sixth reduction gear 136.

[0075] The first reduction gear 131 is fixed to the outer peripheral surface of the first gear shaft 121 and is provided so as to be rotatable integrally with the first gear shaft 121. The first reduction gear 131 is engaged with the output shaft gear 125 and constitutes a first-stage reduction gear unit together with the output shaft gear 125. The first reduction gear 131 is located at the same height as the output shaft gear 125.

[0076] The second reduction gear 132 is formed integrally with the first gear shaft 121 and is provided so as to be rotatable integrally with the first gear shaft 121. The second reduction gear 132 is disposed coaxially with the first reduction gear 131 and has a smaller diameter than the first reduction gear 131. The second reduction gear 132 is located below the output shaft gear 125.

[0077] The third reduction gear 133 is fixed to the outer peripheral surface of the second gear shaft 122 and is provided so as to be rotatable integrally with the second gear shaft 122. The third reduction gear 133 is engaged with the second reduction gear 132 and constitutes a second-stage reduction gear unit together with the second reduction gear 132. The third reduction gear 133 is located below the output shaft gear 125.

[0078] The fourth reduction gear 134 is formed integrally with the second gear shaft 122 and is provided so as to be rotatable integrally with the second gear shaft 122. The fourth reduction gear 134 is disposed coaxially with the third reduction gear 133 and has a smaller diameter than the third reduction gear 133. The fourth reduction gear 134 is located at the same height as the output shaft gear 125.

[0079] The fifth reduction gear 135 is formed integrally with an upper portion of the upstream rotating member 138 of the third gear shaft 123, and is provided so as to be rotatable integrally with the upstream rotating member 138. The fifth reduction gear 135 is engaged with the fourth reduction gear 134, and together with the fourth reduction gear 134, constitutes a third-stage reduction gear unit. The fifth reduction gear 135 is located at the same height as the output shaft gear 125. A portion of the fifth reduction gear 135 is disposed between the upper bearing 44 and the lower bearing 45.

[0080] The sixth reduction gear 136 is formed integrally with an upper portion of the downstream rotation member 139 of the third gear shaft 123, and is provided so as to be rotatable integrally with the downstream rotation member 139. The sixth reduction gear 136 is engaged with the ring gear 126, and together with the ring gear 126, constitutes a fourth-stage reduction gear unit. The sixth reduction gear 136 is disposed coaxially with the fifth reduction gear 135, and has a smaller diameter than the fifth reduction gear 135. The sixth reduction gear 136 is located above the output shaft gear 125. The sixth reduction gear 136 is located at the highest position among the multiple reduction gears 131 to 136.

[0081] <Brake mechanism 21> 3 and 6, brake mechanism 21 is disposed coaxially with output shaft 118 of steering motor 19. Brake mechanism 21 is disposed directly below motor body 117 of steering motor 19. In plan view, the contour of brake mechanism 21 is located within width W1 in the left-right direction of ring gear 126. In plan view, the contour of brake mechanism 21 is located within width W2 in the left-right direction of rotating portion 38 of lower case 13.

[0082] Referring to Figure 3, the brake mechanism 21 includes a brake case 158, an electromagnet 159 housed in the brake case 158, a fixed plate 160 arranged at a distance in the vertical direction from the electromagnet 159, a rotating plate 161 arranged between the electromagnet 159 and the fixed plate 160 and movable in the vertical direction and rotatable integrally with the output shaft 118 of the steering motor 19, a movable plate 162 arranged between the electromagnet 159 and the rotating plate 161 and movable in the vertical direction, and a plurality of compression coil springs 163 arranged between the brake case 158 and the movable plate 162.

[0083] When the outboard motor 1 is not in use, the movable plate 162 presses the rotating plate 161 against the fixed plate 160 due to the biasing force of the compression coil spring 163. This restricts rotation of the rotating plate 161 and the output shaft 118 of the steering motor 19, and also restricts rotation of the lower case 13, which is connected to the output shaft 118 of the steering motor 19 via the steering reduction mechanism 20. In contrast, when the outboard motor 1 is in use, the electromagnet 159 is energized, causing the electromagnet 159 to attract the movable plate 162, and the pressing of the rotating plate 161 against the fixed plate 160 by the movable plate 162 is released. This allows rotation of the rotating plate 161 and the output shaft 118 of the steering motor 19, and also allows rotation of the lower case 13, which is connected to the output shaft 118 of the steering motor 19 via the steering reduction mechanism 20.

[0084] <Rotation angle detection mechanism 22> 7, the rotation angle detection mechanism 22 is housed in the dry chamber S2 of the upper case 11. The rotation angle detection mechanism 22 has a detection shaft 165 provided separately from the plurality of reduction gears 131 to 136, a connecting gear unit 166 (an example of a connecting portion) that connects the third gear shaft 123 (the gear shaft of the fifth reduction gear 135 and the sixth reduction gear 136) and the detection shaft 165, a collar 167 that is arranged coaxially with the detection shaft 165, a resolver 168 (an example of a detecting portion) that detects the rotation angle of the detection shaft 165, a resolver holder 169 that is arranged on the outer periphery of the resolver 168, and a clamping nut 170 (an example of a rotation restricting member) that engages with the detection shaft 165.

[0085] 9 and 10, the detection shaft 165 extends in the vertical direction. A lower portion of the detection shaft 165 is rotatably supported by the separator 27 of the upper case 11. An annular locking protrusion 172 is provided on the outer peripheral surface of the detection shaft 165 at the vertical center portion.

[0086] The connecting gear unit 166 has a drive gear 174 arranged on the third gear shaft 123 and a driven gear 175 arranged on the detection shaft 165 and engaged with the drive gear 174. The drive gear 174 is formed integrally with the manual rotation member 140 of the third gear shaft 123 and is provided to be rotatable integrally with the manual rotation member 140. The drive gear 174 is formed to have a smaller diameter than the sixth reduction gear 136. The driven gear 175 abuts against the locking protrusion 172 of the detection shaft 165 from above. The inner circumferential surface of the driven gear 175 is not spline-connected to the outer circumferential surface of the detection shaft 165, but is fitted therewith to be capable of relative rotation. Referring to FIG. 3, the gear ratio between the drive gear 174 and the driven gear 175 is the same as the gear ratio between the sixth reduction gear 136 and the ring gear 126. Therefore, the rotation speed of the detection shaft 165 is the same as the rotation speed of the lower case 13 .

[0087] 9 and 10, collar 167 has a cylindrical shape extending in the vertical direction. Collar 167 is provided so as to be rotatable integrally with detection shaft 165. Collar 167 is disposed above driven gear 175. The lower end of collar 167 abuts driven gear 175 from above. A pair of flat portions 177 (only one of flat portions 177 is shown in FIG. 10) is provided on the outer peripheral surface of the lower part of collar 167. A coupling recess 178 is provided on the outer peripheral surface of the upper part of collar 167.

[0088] The resolver 168 has a rotor 180 that can rotate integrally with the detection shaft 165 and the collar 167, and a stator 181 that is arranged on the outer periphery of the rotor 180. The rotor 180 is annular, and is coupled to the coupling recess 178 of the collar 167. The stator 181 outputs a detection signal (analog signal) that corresponds to the rotational position of the rotor 180.

[0089] The resolver holder 169 has an annular holder main body 183 arranged on the outer periphery of the stator 181 of the resolver 168, and a protruding piece 184 protruding horizontally from the outer circumferential surface of the holder main body 183. The stator 181 of the resolver 168 is fixed to the holder main body 183. A pin hole 185 is formed in the holder main body 183 in the horizontal direction. The tip of the protruding piece 184 is fixed to the boss 33 of the separator 27 of the upper case 11.

[0090] The clamping nut 170 has an annular shape and is disposed on the inner periphery of the stator 181 of the resolver 168. The outer diameter D1 of the lower end of the clamping nut 170 is larger than the inner diameter D2 of the rotor 180 of the resolver 168. The clamping nut 170 abuts against the rotor 180 from above, thereby preventing the rotor 180 from falling off the collar 167. The collar 167 and the driven gear 175 are sandwiched between the clamping nut 170 and the locking projection 172 of the detection shaft 165.

[0091] The clamping nut 170 is provided so as to be movable in the vertical direction between an allowable position (see the two-dot chain line in FIG. 9 ) and a restricted position (see the solid line in FIG. 9 ) that is shifted downward from the allowable position. When the clamping nut 170 is in the allowable position, the driven gear 175 is not pressed against the locking protrusion 172 of the detection shaft 165. Therefore, rotation of the detection shaft 165 relative to the driven gear 175 is permitted. In contrast, when the clamping nut 170 is in the restricted position, the clamping force of the clamping nut 170 presses the driven gear 175 against the locking protrusion 172 of the detection shaft 165. Therefore, rotation of the detection shaft 165 relative to the driven gear 175 is restricted, and the driven gear 175 and the detection shaft 165 can rotate together.

[0092] <Propulsion and turning of vessel 3> Referring to Figure 2, when the motor shaft 36 of the propulsion motor 12 rotates in the forward direction, the rotation of the motor shaft 36 is transmitted to the planetary reduction mechanism 17 via the upper shaft 94, and the planetary reduction mechanism 17 reduces the speed of the rotation of the motor shaft 36. This reduced rotation of the motor shaft 36 is transmitted to the lower shaft 95, causing the lower shaft 95 to rotate. The rotation of the lower shaft 95 is transmitted to the propeller 14 via the bevel gear mechanism 16, causing the propeller 14 to rotate in one direction around the propeller shaft X2. This imparts a forward thrust to the boat 3, causing the boat 3 to move forward. Similarly, when the motor shaft 36 of the propulsion motor 12 rotates in the reverse direction, the propeller 14 rotates in the opposite direction to the one direction. This imparts a backward thrust to the boat 3, causing the boat 3 to move astern.

[0093] 3, when the output shaft 118 of the steering motor 19 rotates forward, the rotation of the output shaft 118 is transmitted to the steering reduction mechanism 20, and the rotation of the output shaft 118 is reduced by the steering reduction mechanism 20. This reduced rotation of the output shaft 118 is transmitted to the lower case 13, and the lower case 13 and the propeller 14 rotate in one direction about the rotation axis X1. As a result, a turning force in one direction in the left-right direction is applied to the boat 3, and the boat 3 turns to one side in the left-right direction. Similarly, when the output shaft 118 of the steering motor 19 rotates in the reverse direction, the lower case 13 and the propeller 14 rotate in the opposite direction about the rotation axis X1. As a result, a turning force in the other direction in the left-right direction is applied to the boat 3, and the boat 3 turns to the other side in the left-right direction.

[0094] <Effects> In the first embodiment, the steering reduction mechanism 20 is configured with a parallel shaft gear train, and the sixth reduction gear 136 is located above the output shaft gear 125. Therefore, the overall height of the outboard motor 1 (particularly the steering reduction mechanism 20) is lower than when multiple reduction gears 131-136 are arranged downward from the output shaft gear 125 and the sixth reduction gear 136 is located lower than the output shaft gear 125, allowing the outboard motor 1 to be lowered.

[0095] Additionally, the output shaft gear 125 is positioned lower than the sixth reduction gear 136 that engages with the ring gear 126. This allows the upper end of the steering reduction mechanism 20 to be positioned lower, allowing the outboard motor 1 to be lowered even further.

[0096] Furthermore, the output shaft gear 125, the ring gear 126, and the plurality of reduction gears 131 to 136 form a four-stage reduction gear unit, which makes it possible to achieve large reduction in speed without using a planetary gear mechanism.

[0097] (Second embodiment) Next, an outboard motor 201 (an example of a water vehicle propulsion device) according to a second preferred embodiment of the present invention will be described. Note that components other than the steering reduction mechanism 203 are similar to those of the outboard motor 1 according to the first preferred embodiment, and therefore descriptions thereof will be omitted. Regarding the steering reduction mechanism 203, descriptions of the same components as those of the steering reduction mechanism 20 according to the first preferred embodiment will also be omitted.

[0098] <Steering reduction mechanism 203> 11, the steering reduction mechanism 203 is configured by a parallel shaft gear train. The steering reduction mechanism 203 has a plurality of gear shafts 211-214 arranged parallel to the output shaft 118 of the steering motor 19, an output shaft gear 215 arranged coaxially with the output shaft 118 of the steering motor 19, a ring gear 216 arranged coaxially with the rotation axis X1, and a plurality of reduction gears 221-228 provided on the plurality of gear shafts 211-214 and interposed between the output shaft gear 215 and the ring gear 216 in the steering force transmission path R2.

[0099] The multiple gear shafts 211 to 214 include a first gear shaft 211, a second gear shaft 212, a third gear shaft 213, and a fourth gear shaft 214. The multiple gear shafts 211 to 214 are arranged in the order of the first gear shaft 211, the second gear shaft 212, the third gear shaft 213, and the fourth gear shaft 214 from the upstream side to the downstream side.

[0100] The multiple reduction gears 221-228 include a first reduction gear 221 (an example of an upstream end gear), a second reduction gear 222, a third reduction gear 223, a fourth reduction gear 224, a fifth reduction gear 225, a sixth reduction gear 226, a seventh reduction gear 227, and an eighth reduction gear 228 (an example of a downstream end gear). The multiple reduction gears 221-228 are arranged in the following order from the upstream side to the downstream side: first reduction gear 221, second reduction gear 222, third reduction gear 223, fourth reduction gear 224, fifth reduction gear 225, sixth reduction gear 226, seventh reduction gear 227, and eighth reduction gear 228.

[0101] The first reduction gear 221 and the second reduction gear 222 are provided so as to be rotatable integrally with the first gear shaft 211. The first reduction gear 221 is engaged with the output shaft gear 215 and is located at the same height as the output shaft gear 215. The first reduction gear 221 is located at the lowest of the multiple reduction gears 221 to 228. The second reduction gear 222 is located above the output shaft gear 215.

[0102] The third reduction gear 223 and the fourth reduction gear 224 are provided so as to be rotatable integrally with the second gear shaft 212. The third reduction gear 223 is engaged with the second reduction gear 222. The third reduction gear 223 and the fourth reduction gear 224 are located above the output shaft gear 215.

[0103] The fifth reduction gear 225 and the sixth reduction gear 226 are provided so as to be rotatable integrally with the third gear shaft 213. The fifth reduction gear 225 is engaged with the fourth reduction gear 224. The fifth reduction gear 225 and the sixth reduction gear 226 are located above the output shaft gear 215.

[0104] The seventh reduction gear 227 and the eighth reduction gear 228 are provided so as to be rotatable integrally with the fourth gear shaft 214. The seventh reduction gear 227 is engaged with the sixth reduction gear 226. The eighth reduction gear 228 is engaged with the ring gear 216. The seventh reduction gear 227 and the eighth reduction gear 228 are located above the output shaft gear 215.

[0105] <Effects> In this embodiment, the steering reduction mechanism 203 is configured with a parallel shaft gear train, and the second to eighth reduction gears 222 to 228 (i.e., all reduction gears except the first reduction gear 221) are located above the output shaft gear 215. Therefore, the overall height of the outboard motor 201 (particularly the steering reduction mechanism 203) is lower than in a case where the multiple reduction gears 221 to 228 are arranged downward from the output shaft gear 215 and the second to eighth reduction gears 222 to 228 are located lower than the output shaft gear 215, allowing the outboard motor 201 to be lowered.

[0106] In addition, the output shaft gear 215 is located lower than the eighth reduction gear 228 that engages with the ring gear 216. This allows the upper end of the steering reduction mechanism 203 to be positioned lower, allowing the outboard motor 201 to be lowered even further.

[0107] <Modification> In the first and second embodiments, the steering reduction mechanism 20, 203 has a plurality of gear shafts. In other embodiments, the steering reduction mechanism 20, 203 may have only one gear shaft.

[0108] In the first and second embodiments, the outboard motor 1 disposed outside the boat 3 is an example of a waterborne vehicle propulsion device. In other embodiments, an inboard motor disposed inside the boat 3 may be an example of a waterborne vehicle propulsion device.

[0109] Although the description of the specific embodiment has been completed above, the present invention is not limited to the above embodiment and its modifications, and can be modified in a wide range of ways. [Explanation of symbols]

[0110] 1: Outboard motor (an example of a propulsion device for water vehicles) 3: Ship (an example of a water vehicle) 4: Hull 11: Upper case 12: Propulsion motor 13: Lower case 14: Propulsion device 17: Planetary reduction mechanism 19: Steering motor 20: Steering reduction mechanism 21: Brake mechanism 27: Separator 38: Rotating part 117: Motor body 118: Output shaft 121: 1st gear shaft 122: Second gear shaft 123: 3rd gear shaft 125: Output shaft gear 126: Ring gear 131: 1st reduction gear 132: Second reduction gear 133: 3rd reduction gear 134: 4th reduction gear 135: 5th reduction gear 136: 6th reduction gear (an example of a downstream end gear) 203: Steering reduction mechanism 211: 1st gear shaft 212: Second gear shaft 213: 3rd gear shaft 214: 4th gear shaft 215: Output shaft gear 216: Ring gear 221: First reduction gear (an example of an upstream end gear) 222: Second reduction gear 223: 3rd reduction gear 224: 4th reduction gear 225: 5th reduction gear 226: 6th reduction gear 227: 7th reduction gear 228: 8th reduction gear R1: Driving force transmission path R2: Steering force transmission path S1: Oil chamber S2: Dry room W1: Width of the ring gear in the left-right direction X1: Rotating axis X2: Propulsion shaft Y: Collinear

Claims

1. A propulsion device for a water vehicle, comprising: an upper case supported by the hull of the surface vehicle; a propulsion motor housed in the upper case; a lower case supported by the upper case so as to be rotatable about a rotation axis; a propeller supported by the lower case and rotated around a propulsion shaft by the driving force of the propulsion motor; a steering motor housed in the upper case; a steering reduction mechanism that is provided in a steering force transmission path from the steering motor to the lower case and that reduces the speed of rotation of the steering motor, The steering reduction mechanism includes: At least one gear shaft arranged parallel to the output shaft of the steering motor; an output shaft gear arranged coaxially with the output shaft of the steering motor; a ring gear arranged coaxially with the rotation shaft; a plurality of reduction gears provided on the at least one gear shaft and interposed between the output shaft gear and the ring gear in the steering force transmission path, At least one of the reduction gears is located above the output shaft gear when the rotation shaft extends vertically.

2. 2. The water vehicle propulsion device according to claim 1, wherein the at least one gear shaft is located within the width of the ring gear in the left-right direction in a plan view.

3. 3. The water vehicle propulsion device according to claim 1, wherein the outline of the steering motor is located within the width of the ring gear in the left-right direction in a plan view.

4. 3. The water vehicle propulsion device according to claim 1, wherein the output shaft and the rotation shaft of the steering motor are arranged on the same straight line extending in the fore-and-aft direction.

5. a brake mechanism that restricts rotation of the lower case; 3. The water vehicle propulsion device according to claim 1, wherein the contour of the brake mechanism is located within the width of the ring gear in the left-right direction in a plan view.

6. The upper case further includes a separator that divides the internal space of the upper case into an oil chamber and a dry chamber, the steering motor has a motor body accommodated in the dry chamber, 3. The water vehicle propulsion device according to claim 1, wherein the plurality of reduction gears are housed in the oil chamber.

7. a planetary reduction mechanism provided in a drive force transmission path from the propulsion motor to the propeller, the planetary reduction mechanism reducing the rotation speed of the propulsion motor; the lower case has a cylindrical rotating part centered on the rotation axis, the planetary reduction mechanism is disposed on the inner periphery of the rotating part, 3. The waterborne vehicle propulsion device according to claim 1, wherein the plurality of reduction gears are disposed at the same height as the rotating portion.

8. the plurality of reduction gears include a downstream end gear that engages with the ring gear, 3. The waterborne vehicle propulsion device according to claim 1, wherein the downstream end gear is located at the uppermost position among the plurality of reduction gears.

9. the plurality of reduction gears include an upstream end gear that engages with the output shaft gear, 3. The waterborne vehicle propulsion device according to claim 1, wherein the upstream end gear is located at the lowest position among the plurality of reduction gears.

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