Propulsion device and water mobility

Abstract

[Problem] To suppress the impact on the durability of a second drive source and an increase in complexity of the configuration of a propulsion device, while also preventing unintended rotation of a steering unit. [Solution] A propulsion device 100 comprises a planetary mechanism 84 provided on a first drive force transmission path R1 between a first drive source 12 and a propeller 14, and on a second drive force transmission path R2 between a second drive source 17 and a steering unit 13. The planetary mechanism 84 includes a sun rotating body 89, a ring rotating body 92, a planetary rotating body 90, and a carrier rotating body 91. When three rotating elements consisting of the sun rotating body 89, the ring rotating body 92, and the carrier rotating body 91 are designated as a first rotating element, a second rotating element, and a third rotating element in the order of arrangement from the left end side in a collinear diagram, the first rotating element is mechanically connected to one of the first drive source 12 and the second drive source 17, the third rotating element is mechanically connected to the other of the first drive source 12 and the second drive source 17, and the second rotating element is mechanically connected to the propeller 14.

Description

Propulsion device and water mobility

[0001] The present invention relates to a propulsion device and water mobility.

[0002] Conventionally, propulsion devices such as outboard motors that apply propulsive force to a watercraft are known. For example, Patent Document 1 discloses an outboard motor including: an upper case supported by a hull; a lower case supported at a lower portion of the upper case to be rotatable about a first vertically extending axis; a first drive source disposed inside the upper case; an upper drive shaft rotatably supported by the upper case, extending along the first axis, and connected at an upper end thereof to an output shaft of the first drive source; a planetary gear mechanism disposed inside the upper case or the lower case along the first axis and connected to a lower end of the upper drive shaft; a lower drive shaft rotatably supported by the lower case, extending along the first axis, connected at an upper end thereof to the planetary gear mechanism, and having a first bevel gear at a lower end thereof; a propeller shaft rotatably supported by the lower case, extending in a direction orthogonal to the first axis, having a second bevel gear meshing with the first bevel gear at one end thereof, and having a propeller at the other end protruding from the lower case; and a second drive source that applies torque about the first axis to the lower case.

[0003] In Patent Document 1, the planetary gear mechanism includes a sun gear, a planetary carrier that rotatably supports a plurality of planetary gears meshing with the sun gear, and an internal gear meshing with the plurality of planetary gears. The sun gear is connected to the lower end of the upper drive shaft and rotates integrally with the upper drive shaft. The internal gear is fixed to the lower case and rotates integrally with the lower case. A cylindrical connecting portion is provided at an upper end of the lower case. A disk portion protruding radially outward is provided at an upper end of the connecting portion. A first gear is formed on an outer periphery of the disk portion. A second gear meshing with the first gear is provided on an output shaft of the second drive source.

[0004] Japanese Unexamined Patent Publication No. 2022-117651

[0005] In Patent Document 1, the first and second gears are composed of external gears (spur gears) and do not have a so-called "self-locking function" (a function that restricts the transmission of power from the output side to the input side). In other words, the first and second gears do not have a function to hold the lower case in a stopped state. Therefore, there is a risk that the lower case and internal gears may rotate unintentionally.

[0006] To suppress the rotation of the lower case and internal gear as described above, it is conceivable that the second drive source continuously generates torque to hold the lower case and internal gear in a stationary state. However, if such measures are taken, the second drive source will have to continuously drive to hold the lower case in a stationary state, which may affect the durability of the second drive source. On the other hand, adding a mechanism to hold the lower case and internal gear in a stationary state (for example, a braking mechanism) may lead to increased complexity in the configuration of the propulsion system.

[0007] In view of the above background, one aspect of the present invention aims to provide a propulsion system and water mobility that can suppress the impact on the durability of the second drive source and the complexity of the propulsion system configuration, and that can suppress unintended rotation of the steering section.

[0008] To solve the above problems, one aspect of the present invention provides a propulsion device comprising: a first drive source; a thruster provided to rotate around a rotation axis by a driving force output from the first drive source and to be submerged in external water; a second drive source different from the first drive source; a steering unit provided to rotate around a rotation axis by a driving force output from the second drive source; and a planetary mechanism provided on a first drive force transmission path between the first drive source and the thruster, and on a second drive force transmission path between the second drive source and the steering unit, wherein the planetary mechanism comprises a sun rotating body, a ring rotating body, and a plastic plate arranged between the sun rotating body and the ring rotating body so as to transmit power. The system comprises a planetary rotating body and a carrier rotating body that supports the planetary rotating body so that it can rotate and revolve. The three rotating elements, consisting of the sun rotating body, the ring rotating body, and the carrier rotating body, are configured such that their rotational speeds lie on a single straight line in the collinear diagram, satisfying a collinear relationship. Of the three rotating elements, when they are arranged in the collinear diagram from left to right as the first rotating element, the second rotating element, and the third rotating element, the first rotating element is mechanically connected to either the first drive source or the second drive source, the third rotating element is mechanically connected to either the first drive source or the second drive source, and the second rotating element is mechanically connected to the thruster.

[0009] According to the above embodiment, it is possible to suppress the impact on the durability of the second drive source and the complexity of the propulsion system configuration, and to suppress the steering section from rotating unintentionally.

[0010] Side view showing an outboard motor according to the first embodiment Schematic diagram showing an outboard motor according to the first embodiment Cross-sectional view showing the upper part of an outboard motor according to the first embodiment (A) Schematic diagram showing the rotation angle range of the lower case according to the first embodiment, (B) Schematic diagram showing the engagement angle range of the worm wheel according to the first embodiment Schematic diagram showing method 1 for setting the gear ratio of the planetary mechanism according to the first embodiment Schematic diagram showing method 2 for setting the gear ratio of the planetary mechanism according to the first embodiment Flowchart showing range change control according to the first embodiment Schematic diagram showing an outboard motor according to the second embodiment Schematic diagram showing an outboard motor according to the third embodiment Collinear diagram showing the rotation speed of the rotating elements of the planetary mechanism according to the second and third embodiments Schematic diagram showing an outboard motor according to the fourth embodiment

[0011] <First Embodiment> Hereinafter, an outboard motor 1 (an example of a propulsion device) according to the first embodiment of the present invention will be described with reference to Figures 1 to 7. The arrow Fr in each figure indicates the front of the outboard motor 1.

[0012] <Outboard Motor 1> Referring to Figure 1, the outboard motor 1 is a device for providing propulsion to a vessel 3 such as a boat (an example of a water-based mobile object and water mobility). The outboard motor 1 is fixed to the rear end of the hull 4 of the vessel 3 via a fixing device 6. The outboard motor 1 is tiltable around a tilt shaft 7 provided on the fixing device 6.

[0013] Referring to Figures 1 and 2, the outboard motor 1 comprises an upper case 11 supported at the rear end of the hull 4 via a fixing device 6, a first motor 12 (an example of a first drive source) housed in the upper case 11, a lower case 13 (an example of a steering section) supported in the upper case 11 so as to be rotatable around a rotation axis X1, a thruster 14 supported in the lower case 13 and rotating around a rotation axis X2 by the driving force of the first motor 12, a drive shaft 15 connected to the first motor 12 and extending along the rotation axis X1, a bevel gear mechanism 16 housed in the lower case 13 and connecting the drive shaft 15 and the thruster 14, a second motor 17 (an example of a second drive source different from the first drive source) housed in the upper case 11, a steering mechanism 18 housed in the upper case 11 and transmitting the driving force of the second motor 17 to the lower case 13, and a control device 19 housed in the upper case 11. Furthermore, the outboard motor 1 does not have a planetary mechanism (see the second and third embodiments) for changing the speed of rotation of the first motor 12.

[0014] The components of the outboard motor 1 will be described below based on the state in which the rotation axis X1 extends in the vertical direction and the rotation axis X2 extends in the longitudinal direction (see Figures 1 and 2). Hereafter, when referring to the circumferential direction, radial direction, and axial direction, they refer to the circumferential direction, radial direction, and axial direction of the rotation axis X1, respectively.

[0015] <Upper Case 11> Referring to Figure 3, the upper case 11 comprises an upper wall portion 21 and a lower wall portion 22 located below the upper wall portion 21. The upper wall portion 21 is box-shaped with an opening facing downward. The lower wall portion 22 comprises a cylindrical inner circumferential wall 24, a cylindrical outer circumferential wall 25 located on the outer circumference of the inner circumferential wall 24, an annular connecting wall 26 connecting the lower end of the inner circumferential wall 24 and the lower end of the outer circumferential wall 25, and an annular protruding wall 27 protruding from the inner circumferential surface of the connecting wall 26. The upper end of the outer circumferential wall 25 is fixed to the lower end of the upper wall portion 21. A support plate 29 is fixed to the upper end of the inner circumferential wall 24. The support plate 29 comprises an annular portion 31 extending in the radial direction and a cylindrical portion 32 protruding downward from the radially inner end of the annular portion 31.

[0016] <First Motor 12> Referring to Figures 2 and 3, the first motor 12 is composed of an electric motor. The first motor 12 comprises a first motor body 34 and a first motor shaft 35 that protrudes downward from the first motor body 34.

[0017] <Lower Case 13> Referring to Figures 2 and 3, the lower case 13 rotates around the rotation axis X1 by the driving force output from the second motor 17. The lower case 13 is capable of at least one rotation, and after an integer number of rotations, the propulsion direction of the ship 3 returns to its original direction. The lower case 13 is the part that can change the direction of the rotation axis X2 of the propeller 14. The upper end of the lower case 13 is positioned below the upper end of the upper case 11, and the lower end of the lower case 13 is positioned below the lower end of the upper case 11. In other words, the lower case 13 is positioned below the upper case 11. The lower case 13 comprises a rotating part 37 and a case body 38 positioned below the rotating part 37.

[0018] The rotating part 37 is cylindrical in shape with a rotation axis X1 as its center. The portion of the rotating part 37 excluding the lower end is housed in the upper case 11. The rotating part 37 comprises a large diameter portion 40, a small diameter portion 41 positioned below the large diameter portion 40, a reduced diameter portion 42 positioned between the large diameter portion 40 and the small diameter portion 41, and a fixed portion 43 protruding radially outward from the lower end of the small diameter portion 41. The inner diameter of the small diameter portion 41 is smaller than the inner diameter of the large diameter portion 40. The small diameter portion 41 is positioned radially inward of the protruding wall 27 of the upper case 11. A sealing member 44 is positioned between the small diameter portion 41 and the protruding wall 27. The inner diameter of the reduced diameter portion 42 gradually decreases from the upper side (large diameter portion 40 side) to the lower side (small diameter portion 41 side).

[0019] A first bearing 45 is positioned on the outer circumference of the large-diameter portion 40 of the rotating portion 37. The first bearing 45 is positioned between the large-diameter portion 40 and the upper part of the inner circumferential wall 24 of the upper case 11. A second bearing 46 is positioned on the outer circumference of the small-diameter portion 41 of the rotating portion 37. The second bearing 46 is positioned between the small-diameter portion 41 and the lower part of the inner circumferential wall 24 of the upper case 11. With this configuration, the lower case 13 is rotatably supported by the upper case 11 via the first bearing 45 and the second bearing 46. The first bearing 45 and the second bearing 46 are positioned coaxially with the rotation axis X1 and side by side in the vertical direction (axial direction). The second bearing 46 is positioned below the first bearing 45, with a vertical gap between them.

[0020] The case body 38 comprises a cylindrical shaft case 48 extending in the vertical direction and a bullet-shaped gear case 49 positioned below the shaft case 48. The upper end of the shaft case 48 is fixed to the fixing portion 43 of the rotating portion 37 via a plurality of bolts B.

[0021] <Thruster 14> Referring to Figure 2, the thruster 14 is installed to rotate around the rotation axis X2 by the driving force output from the first motor 12 and to be submerged in external water (seawater, freshwater, etc.). The thruster 14 together with the lower case 13 constitutes the lower unit 50. The thruster 14 is rotatable integrally with the lower case 13 around the rotation axis X1 and is rotatable relative to the lower case 13 around the rotation axis X2. The thruster 14 includes a propeller shaft 51 extending along the rotation axis X2 and a propeller 52 fixed to the rear of the propeller shaft 51. The front part of the propeller shaft 51 is housed in the gear case 49 of the lower case 13 and is rotatably supported in the gear case 49. The propeller 52 is also called a screw or screw propeller. The propeller 52 may be a conventional propeller as shown in Figure 2, or it may be a counter-rotating propeller, a variable-pitch propeller, or the like.

[0022] <Drive shaft 15> Referring to Figures 2 and 3, the drive shaft 15 extends in the vertical direction. The upper end of the drive shaft 15 is fixed to the first motor shaft 35 of the first motor 12. This allows the drive shaft 15 to rotate integrally with the first motor shaft 35 of the first motor 12.

[0023] The upper part of the drive shaft 15 is housed in the upper case 11. The upper part of the drive shaft 15 is positioned on the inner circumference of the rotating portion 37 of the lower case 13. The upper part of the drive shaft 15 is rotatably supported on the small diameter portion 41 of the rotating portion 37 via a shaft bearing 53. The lower part of the drive shaft 15 passes through the shaft case 48 of the lower case 13. The lower end of the drive shaft 15 reaches the gear case 49 of the lower case 13.

[0024] <Bevel Gear Mechanism 16> Referring to Figure 2, the bevel gear mechanism 16 is housed in the gear case 49 of the lower case 13. The bevel gear mechanism 16 includes a first bevel gear 55 arranged coaxially with the rotation axis X1, and a second bevel gear 56 arranged coaxially with the rotation axis X2 and engaging with the first bevel gear 55. The first bevel gear 55 is fixed to the lower end of the drive shaft 15 and is rotatably mounted integrally with the drive shaft 15. The second bevel gear 56 is fixed to the front end of the propeller shaft 51 of the thruster 14 and is rotatably mounted integrally with the thruster 14.

[0025] <Second Motor 17> Referring to Figures 2 and 3, the second motor 17 is composed of an electric motor. The second motor 17 comprises a second motor body 58 and a second motor shaft 59 that protrudes horizontally from the second motor body 58.

[0026] <Steering mechanism 18> Referring to Figures 2 and 3, the steering mechanism 18 comprises a worm gear set 61, a rotating body 62 connected to the worm gear set 61, and a speed change mechanism 63 connecting the rotating body 62 to the lower case 13.

[0027] The worm gear set 61 comprises a worm 65 and a worm wheel 66 that meshes (engages) with the worm 65. The worm 65 extends horizontally. The worm 65 is fixed to the outer circumferential surface of the second motor shaft 59 of the second motor 17. That is, the worm 65 is driven by the second motor 17. The worm wheel 66 is arranged coaxially with the drive shaft 15 around the rotation axis X1.

[0028] A worm gear set 61 refers to a set consisting of a worm 65, which is a threaded shaft, and a corresponding worm wheel 66. The worm wheel 66 is a helical gear that meshes with the worm 65. A worm gear set 61 is classified as a misaligned shaft gear. The angle of intersection of the shafts is, for example, 90 degrees, but is not limited to that. A worm gear set 61 has the characteristic of a large gear ratio, and is therefore often used when the direction of rotation needs to be changed and a large gear ratio is required.

[0029] The rotating body 62 has a bottomed cylindrical shape. The rotating body 62 is arranged coaxially with the drive shaft 15 around the rotation axis X1. A worm wheel 66 is fixed to the outer circumferential surface of the rotating body 62. The rotating body 62 is rotatable together with the worm wheel 66 around the rotation axis X1. A projection 68 that protrudes downward is provided on the bottom surface of the rotating body 62.

[0030] The gear shift mechanism 63 is provided in the rotational transmission path R from the worm wheel 66 to the lower case 13. The gear shift mechanism 63 is a reduction mechanism that reduces rotation based on the rotational transmission direction from the worm wheel 66 to the lower case 13. The gear shift mechanism 63 is not a mechanism that switches between multiple gear ratios, but a mechanism with a fixed gear ratio. The gear shift mechanism 63 is arranged around the rotation axis X1, coaxially with the rotation axis X1 and the drive shaft 15. The gear shift mechanism 63 is located on the inner circumference of the large diameter portion 40 of the rotating portion 37. Most of the gear shift mechanism 63 (excluding the upper end portion) is located below the oil level L (static oil level) of the outboard motor 1 when the outboard motor 1 is stopped. In other embodiments, the entire gear shift mechanism 63 may be located below the oil level L.

[0031] The entire gear shift mechanism 63 is positioned below the upper end of the first bearing 45. The upper part of the gear shift mechanism 63 is positioned at the same height as the first bearing 45. In other words, the upper part of the gear shift mechanism 63 overlaps with the first bearing 45 in the axial direction. The lower part of the gear shift mechanism 63 is positioned below the first bearing 45 and above the second bearing 46. In other embodiments, the entire gear shift mechanism 63 may be positioned between the first bearing 45 and the second bearing 46 in the axial direction.

[0032] For example, the gear shift mechanism 63 is composed of a star-type planetary mechanism. In other embodiments, the gear shift mechanism 63 may be composed of a planetary mechanism other than a star type (for example, a solar-type or planetary-type planetary mechanism).

[0033] The transmission mechanism 63 includes a sun gear 70, a plurality of planetary gears 71 that engage with the sun gear 70, a carrier 72 that rotatably supports the plurality of planetary gears 71, and a ring gear 73 that engages with the plurality of planetary gears 71. The ring gear 73 is also called an internal gear.

[0034] The sun gear 70 is integrally provided with the protruding portion 68 of the rotating body 62 and is rotatable together with the rotating body 62. The carrier 72 is integrally provided with the cylindrical portion 32 of the support plate 29 and is not rotatable. The ring gear 73 is fixed to the inner circumferential surface of the large diameter portion 40 of the rotating portion 37 and is rotatable together with the rotating portion 37.

[0035] <Control device 19> Referring to Figure 2, the control device 19 is a computer having a processor and a memory that is communicatively connected to the processor. The control device 19 is connected to the first motor 12 and the second motor 17 and controls the driving of the first motor 12 and the second motor 17.

[0036] The control device 19 is connected to an operating unit that receives steering input from the user. When the operating unit receives steering input from the user, a steering signal is transmitted from the operating unit to the control device 19. The control device 19 drives the second motor 17 in response to the steering signal from the operating unit, and the second motor 17 and the steering mechanism 18 steer the outboard motor 1 and the vessel 3.

[0037] <Propulsion and Turning of Ship 3> Referring to Figure 2, when the first motor shaft 35 of the first motor 12 rotates in the forward direction, the rotation of the first motor shaft 35 is transmitted to the drive shaft 15, causing the drive shaft 15 to rotate. The rotation of the drive shaft 15 is transmitted to the thruster 14 via the bevel gear mechanism 16, causing the thruster 14 to rotate in one direction around the rotation axis X2. This imparts a forward thrust to the ship 3, causing the ship 3 to move forward. Similarly, when the first motor shaft 35 of the first motor 12 rotates in the reverse direction, the thruster 14 rotates in the opposite direction around the rotation axis X2. This imparts a rearward thrust to the ship 3, causing the ship 3 to move backward.

[0038] Referring to Figure 3, when the second motor shaft 59 of the second motor 17 rotates in the forward direction, the worm 65 rotates integrally with the second motor shaft 59, and the worm wheel 66 that engages with the worm 65 rotates. As a result, the rotation of the second motor shaft 59 is reduced in primary speed by the worm gear set 61. The rotation of the worm wheel 66 is transmitted to the sun gear 70 via the rotating body 62, causing the sun gear 70 to rotate. The rotation of the sun gear 70 is transmitted to the ring gear 73 via a plurality of planetary gears 71, causing the ring gear 73 to rotate. As a result, the rotation of the second motor shaft 59 is reduced in secondary speed by the speed change mechanism 63. The rotation of the ring gear 73 is transmitted to the rotating part 37 of the lower case 13, causing the lower case 13 and the thruster 14 to rotate in one direction around the rotation axis X1. As a result, the outboard motor 1 and the vessel 3 are steered to one side in the left-right direction and turn to that side. Similarly, when the second motor shaft 59 of the second motor 17 is reversed, the lower case 13 and the thruster 14 rotate around the rotation axis X1 in the opposite direction to the above one direction. As a result, the outboard motor 1 and the vessel 3 are steered to the other side in the left-right direction and turn to the other side.

[0039] <Normal rotation angle range TR of the lower case 13 and normal engagement angle range ER of the worm wheel 66> Referring to Figure 4(A), the lower case 13 is configured to rotate together with the propeller 14 within a predetermined normal rotation angle range TR when the propeller 14 is rotating (when the ship 3 is being propelled).

[0040] The normal rotation angle range TR includes a first rotation range T1 and a pair of second rotation ranges T2 located on both sides of the first rotation range T1. The first rotation range T1 includes the center angle TC of the normal rotation angle range TR (hereinafter referred to as "rotation center angle TC"). When the lower case 13 is at the rotation center angle TC, the steering angle of the vessel 3 becomes zero (i.e., the vessel 3 moves in a straight line).

[0041] When the vessel 3 is traveling at normal speed on the open sea, the lower case 13 rotates only within the first rotation range T1. In contrast, when the vessel 3 is docking at low speed in response to the operator's actions, the lower case 13 rotates within the first rotation range T1 or the pair of second rotation ranges T2 (i.e., the entire range of the normal rotation angle TR). Therefore, the first rotation range T1 is used more frequently than the pair of second rotation ranges T2.

[0042] Referring to Figure 4(B), the worm wheel 66 is configured to engage with the worm 65 within a predetermined normal engagement angle range ER when the propeller 14 is rotating (when the ship 3 is being propelled). The normal engagement angle range ER corresponds to the normal rotation angle range TR of the lower case 13. The normal engagement angle range ER is calculated by multiplying the normal rotation angle range TR of the lower case 13 by the gear ratio of the transmission mechanism 63. For example, if the normal rotation angle range TR is 60 degrees (rotation center angle TC ± 30 degrees) and the gear ratio of the transmission mechanism 63 is approximately 2.17, then the normal engagement angle range ER is approximately 130 degrees (= 60 degrees × 2.17).

[0043] The regular engagement angle range ER includes a first engagement range E1 and a pair of second engagement ranges E2 located on both outer sides of the first engagement range E1. The first engagement range E1 includes a center angle EC of the regular engagement angle range ER (hereinafter referred to as "engagement center angle EC"). When the worm wheel 66 is at the engagement center angle EC, the lower case 13 is at the rotation center angle TC, and the steering angle of the ship 3 becomes zero (that is, the ship 3 travels straight). The first engagement range E1 and the pair of second engagement ranges E2 respectively correspond to the first rotation range T1 of the lower case 13 and the pair of second rotation ranges T2 of the lower case 13. The first engagement range E1 is calculated by multiplying the first rotation range T1 of the lower case 13 by the gear ratio of the speed change mechanism 63. For example, when the first rotation range T1 is 30 degrees and the gear ratio of the speed change mechanism 63 is approximately 2.17, the first engagement range E1 is approximately 65 degrees (=30 degrees×2.17). Each second engagement range E2 is calculated by dividing a value obtained by subtracting the first engagement range E1 from the regular engagement angle range ER by 2. For example, when the regular engagement angle range ER is 130 degrees and the first engagement range E1 is 65 degrees, each second engagement range E2 is 32.5 degrees (=(130-65) / 2).

[0044] When the ship 3 is traveling on the ocean at a normal speed, the worm wheel 66 engages with the worm 65 only in the first engagement range E1. In contrast, when the ship 3 berths at a low speed in response to the operator's operation, the worm wheel 66 engages with the worm 65 in the first engagement range E1 or the pair of second engagement ranges E2 (that is, the entire area of the regular engagement angle range ER). Therefore, the use frequency of the first engagement range E1 is higher than the use frequency of the pair of second engagement ranges E2.

[0045] <Setting Method for Gear Ratio of Speed Change Mechanism 63> The gear ratio of the speed change mechanism 63 is set such that the regular engagement angle range ER of the worm wheel 66 is changed by rotating the lower case 13 one rotation (by rotating the lower case 13 a predetermined integer number of rotations). Specifically, the gear ratio of the speed change mechanism 63 is set to a non-integer multiple greater than 1. Hereinafter, the setting method for the gear ratio of the speed change mechanism 63 will be described in detail.

[0046] First, a first method for setting the gear ratio of the speed change mechanism 63 will be described with reference to FIGS. 5(A) and 5(B). In FIGS. 5(A) and 5(B), the normal engagement angle range ER of the worm wheel 66 before rotating the lower case 13 one full rotation is indicated by a two-dot chain line, and the normal engagement angle range ER of the worm wheel 66 after rotating the lower case 13 one full rotation is indicated by a solid line. Arrow D in FIGS. 5(A) and 5(B) indicates the rotation direction of the worm wheel 66 accompanying rotation of the lower case 13.

[0047] Referring to FIGS. 4(A) and 5(A), for example, when the normal rotation angle range TR of the lower case 13 is 60 degrees, if the gear ratio of the speed change mechanism 63 is set to 2.4, the normal engagement angle range ER of the worm wheel 66 becomes 144 degrees (=60 degrees×2.4). In such a setting, when the lower case 13 is rotated one full rotation, the worm wheel 66 rotates 2 rotations + 144 degrees (i.e., 2.4 rotations). Therefore, the normal engagement angle range ER after rotating the lower case 13 one full rotation does not overlap with the normal engagement angle range ER before rotating the lower case 13 one full rotation.

[0048] Referring to FIGS. 4(A) and 5(B), for example, when the normal rotation angle range TR of the lower case 13 is 60 degrees, if the gear ratio of the speed change mechanism 63 is set to 2.57, the normal engagement angle range ER of the worm wheel 66 becomes 154.2 degrees (=60 degrees×2.57). In such a setting, when the lower case 13 is rotated one full rotation, the worm wheel 66 rotates 2 rotations + 205.2 degrees (i.e., 2.57 rotations). Therefore, the normal engagement angle range ER after rotating the lower case 13 one full rotation does not overlap with the normal engagement angle range ER before rotating the lower case 13 one full rotation.

[0049] As described above, in the gear ratio setting method 1 for the gear shift mechanism 63, the gear ratio of the gear shift mechanism 63 is set so that the normal engagement angle range ER after one rotation of the lower case 13 does not overlap with the normal engagement angle range ER before one rotation of the lower case 13. For example, if the normal rotation angle range TR is 60 degrees, setting the gear ratio of the gear shift mechanism 63 to 2.4 to 2.57 prevents the normal engagement angle range ER after one rotation of the lower case 13 from overlapping with the normal engagement angle range ER before one rotation of the lower case 13. As a result, the unused normal engagement angle range ER can be used by rotating the lower case 13 once, thereby improving the durability of the worm wheel 66.

[0050] Next, the second method for setting the gear ratio of the transmission mechanism 63 will be explained with reference to Figures 6(A) and 6(B). Figure 6(A) shows the normal engagement angle range ER before the lower case 13 is rotated once, and Figure 6(B) shows the normal engagement angle range ER after the lower case 13 has been rotated once. The arrow D in Figures 6(A) and 6(B) indicates the direction of rotation of the worm wheel 66 as the lower case 13 rotates. The normal engagement angle range ER is calculated by multiplying the normal rotation angle range TR of the lower case 13 by the gear ratio i of the transmission mechanism 63. The gear ratio i is expressed as i = n + δ, using an integer n and a decimal δ. The shift angle θ of the normal engagement angle range ER when the lower case 13 is rotated once is expressed as θ = 360 × δ.

[0051] Referring to Figures 4(A), 6(A), and 6(B), for example, if the normal rotation angle range TR and the first rotation range T1 of the lower case 13 are 60 degrees and 27.7 degrees, respectively, and the gear ratio of the transmission mechanism 63 is approximately 2.17, then the normal engagement angle range ER and the first engagement range E1 of the worm wheel 66 will be approximately 130 degrees (= 60 degrees × 2.17) and approximately 60 degrees (= 27.7 degrees × 2.17), respectively. In this setting, when the lower case 13 is rotated once, the worm wheel 66 rotates 2 times + approximately 60 degrees (i.e., approximately 2.17 times). Therefore, the first engagement range E1 after one rotation of the lower case 13 does not overlap with the first engagement range E1 before one rotation of the lower case 13, and the second engagement range E2 after one rotation of the lower case 13 overlaps overall with the second engagement range E2 before one rotation of the lower case 13. In other embodiments, the second engagement range E2 after rotating the lower case 13 once may partially overlap with the second engagement range E2 before rotating the lower case 13 once.

[0052] As described above, in the method 2 for setting the gear ratio of the gear shift mechanism 63, the gear ratio of the gear shift mechanism 63 is set such that the first engagement range E1 after one rotation of the lower case 13 does not overlap with the first engagement range E1 before one rotation of the lower case 13. This allows the unused first engagement range E1 to be used, thereby improving the durability of the worm wheel 66.

[0053] Furthermore, as mentioned above, the second engagement range E2 is used only when the vessel 3 is propelled at a low speed (i.e., when water resistance is small). Therefore, the load on the second engagement range E2 when the vessel 3 turns is small, and the amount of wear on the second engagement range E2 is small. Taking this into consideration, in the method 2 for setting the gear ratio of the gear transmission mechanism 63, the gear ratio of the gear transmission mechanism 63 is set such that the second engagement range E2 after one rotation of the lower case 13 overlaps with the second engagement range E2 before one rotation of the lower case 13. This makes it possible to increase the number of times the first engagement range E1 can be refreshed (the number of times the unused first engagement range E1 can be used after one rotation of the lower case 13) compared to the case where the normal engagement angle range ER after one rotation of the lower case 13 does not overlap overall with the normal engagement angle range ER before one rotation of the lower case 13 (see method 1 for setting the gear ratio of the gear transmission mechanism 63).

[0054] <Range Change Control> Next, the range change control performed by the control device 19 will be described with reference to Figure 7. Range change control is a control for changing the normal engagement angle range ER of the worm wheel 66.

[0055] When range change control is initiated, the control device 19 determines whether or not the rotation of the thruster 14 has stopped (step ST1). For example, if the rotational speed of the first motor 12 is zero, the control device 19 determines that the rotation of the thruster 14 has stopped. On the other hand, if the rotational speed of the first motor 12 is not zero, the control device 19 determines that the rotation of the thruster 14 has not stopped. In other embodiments, in step ST1, the control device 19 may determine whether or not the ship 3 is stopped or in a predetermined low-speed state, instead of whether or not the rotation of the thruster 14 has stopped.

[0056] If the rotation of the thruster 14 has not stopped (Step ST1: No), the control device 19 terminates the range change control without executing the range change process described later. If the rotation of the thruster 14 has stopped (Step ST1: Yes), the control device 19 determines whether or not a predetermined range change condition is met (Step ST2). For example, the control device 19 determines that the range change condition is met if at least one of the following conditions 1 to 5 is met. Condition 1: The cumulative distance traveled by the vessel 3 has reached a predetermined distance or more. Condition 2: The cumulative travel time of the vessel 3 has reached a predetermined time or more. Condition 3: The amount of backlash of the worm gear set 61 from the time the second motor 17 is driven until the steering of the outboard motor 1 begins has reached a predetermined amount or more. Condition 4: The steering response index has changed from a reference value to a predetermined value or more when a constant load is applied to the steering mechanism 18 (for example, the steering acceleration of the outboard motor 1 has reached a predetermined value or more). Condition 5: The estimated wear amount of the worm wheel 66 has reached a predetermined value or more.

[0057] When determining whether the above condition 4 is met, a constant load may be applied to the steering mechanism 18 by applying a constant torque to the first motor 12 while the vessel 3 is moored (or at low speed) (applying a constant torque to the first motor 12 generates a torque reaction force in the steering mechanism 18). Alternatively, a constant load may be applied to the steering mechanism 18 by attaching a jig that applies a constant frictional resistance to the propeller shaft 51.

[0058] When determining whether the above condition 5 is met, the amount of wear on the worm wheel 66 may be estimated by calculating P (surface pressure) and V (surface velocity) on the tooth surface of the worm 65 based on the torque applied to the worm 65 and the rotational speed of the worm 65, and then estimating the amount of wear on the worm wheel 66 based on data showing the relationship between the calculated P and V and the amount of wear on the worm wheel 66.

[0059] If the range change condition is not met (Step ST2: No), the control device 19 terminates the range change control without executing the range change process described later. If the range change condition is met (Step ST2: Yes), the control device 19 executes the range change process (Step ST3). In the range change process, the control device 19 changes the normal engagement angle range ER of the worm wheel 66 by rotating the lower case 13 once with the second motor 17. At this time, the control device 19 may determine that the lower case 13 has rotated once based on signals from an angle detector (for example, the motor encoder of the second motor 17, the angle sensor of the lower case 13) or a home position sensor.

[0060] Once the range change process (step ST3) is complete, the control device 19 resets the range change conditions (step ST4). More specifically, the control device 19 sets the cumulative mileage for condition 1, the cumulative mileage for condition 2, etc., to zero. Once the reset of the range change conditions is complete, the control device 19 terminates the range change control.

[0061] As described above, the control device 19 executes a control method for the outboard motor 1, comprising: a step of determining whether the rotation of the propeller 14 has stopped or whether the vessel 3 is stopped or in a predetermined low-speed state (step ST1); a step of determining whether the range change condition is met if the rotation of the propeller 14 has stopped or the vessel 3 is stopped or in a predetermined low-speed state (step ST1: Yes) (step ST2); and a step of changing the normal engagement angle range ER of the worm wheel 66 by rotating the lower case 13 a predetermined integer number of times if the range change condition is met (step ST2: Yes) (step ST3).

[0062] In this embodiment, the control device 19 determines whether the range change condition is met based on five indicators (cumulative mileage of the vessel 3, cumulative mileage of the vessel 3, backlash amount of the worm gear set 61, steering response indicator, and estimated wear amount of the worm wheel 66) (step ST2). In other embodiments, the control device 19 may determine whether the range change condition is met based on only some of the above five indicators. The control device 19 may determine whether the range change condition is met based on at least one of the above five indicators.

[0063] <Effects> The steering mechanism 18 includes a worm gear set 61 comprising a worm 65 driven by the second motor 17 and a worm wheel 66 engaged with the worm 65, and a speed change mechanism 63 provided in the rotational transmission path R from the worm wheel 66 to the lower case 13. By adopting this configuration, the rotation of the second motor 17 can be reduced by both the worm gear set 61 and the speed change mechanism 63. Therefore, the rotation of the second motor 17 can be significantly reduced without setting a large gear ratio for the worm gear set 61. As a result, a large steering torque can be generated without increasing the size of the worm wheel 66.

[0064] However, if the worm wheel 66 engages with the worm 65 only within a limited normal engagement angle range ER, wear of the normal engagement angle range ER is likely to occur. Therefore, in this embodiment, when the range change condition is met, the normal engagement angle range ER is automatically changed by a range change process. This suppresses wear of the normal engagement angle range ER and improves the durability of the worm wheel 66.

[0065] Referring to Figure 2, if the vertical distance between the first bearing 45 and the second bearing 46 is d1, and the vertical distance between the second bearing 46 and the propeller shaft 51 is d2, then the load F1 acting on the first bearing 45 and the load F2 acting on the second bearing 46 when the thruster 14 rotates are theoretically expressed by equations (1) and (2) below, respectively. However, in equations (1) and (2) below, F represents the thrust force generated by the rotation of the thruster 14.

[0066] In this embodiment, due to the layout of the outboard motor 1, the propeller shaft 51 is far from the upper case 11, resulting in a large value for d2. Consequently, as the value of d2 / d1 increases, the loads F1 and F2 on the first and second bearings 45 and 46 also increase. In particular, if foreign objects such as driftwood collide with the outboard motor 1, in addition to the loads F1 and F2 due to the thrust, the load from the collision with the foreign object is also applied to the first and second bearings 45 and 46, potentially resulting in an even larger load on the first and second bearings 45 and 46.

[0067] Therefore, in this embodiment, the value of d1 is increased by arranging the first and second bearings 45 and 46 with a gap between them in the vertical direction. This suppresses the increase in the value of d2 / d1, and thus reduces the loads F1 and F2 applied to the first and second bearings 45 and 46. Furthermore, in this embodiment, the strength of the first and second bearings 45 and 46 is increased by increasing their diameter.

[0068] Incidentally, the outboard motor 1 may be equipped with a planetary mechanism for changing the speed of the rotation of the first motor 12 (see the second and third embodiments). Since such a planetary mechanism rotates at high speed at all times when the outboard motor 1 is in operation, if it is placed below the oil level L, it may lead to an increase in frictional resistance. In contrast, the speed change mechanism 63 rotates only when the ship 3 is turned, so the rotation time is short and it has little effect on frictional resistance. Therefore, in this embodiment, most of the speed change mechanism 63 (excluding the upper end) is placed below the oil level L. This makes it possible to effectively lubricate the speed change mechanism 63.

[0069] Furthermore, in the above embodiment, instead of both the upper case 11 and the lower case 13 rotating relative to the vessel 3, the lower case 13 rotates relative to the upper case 11, which is fixed to the vessel 3. By adopting this configuration, the mass of the rotating components is reduced compared to the case where both the upper case 11 and the lower case 13 rotate, and therefore the energy required for steering the outboard motor 1 and the vessel 3 can be reduced.

[0070] <Modification> In the above embodiment, the gear ratio of the gear shift mechanism 63 is set such that the normal engagement angle range ER of the worm wheel 66 is changed by rotating the lower case 13 once. In other embodiments, the gear ratio of the gear shift mechanism 63 may be set such that the normal engagement angle range ER of the worm wheel 66 is changed by rotating the lower case 13 multiple times. In other words, the gear ratio of the gear shift mechanism 63 only needs to be set such that the normal engagement angle range ER of the worm wheel 66 is changed by rotating the lower case 13 a predetermined integer number of times.

[0071] In the above embodiment, the worm wheel 66 is connected to the transmission mechanism 63 via the rotating body 62. In other embodiments, the worm wheel 66 may be directly connected to the transmission mechanism 63.

[0072] <Second Embodiment> Hereinafter, an outboard motor 81 (an example of a propulsion device) according to the second embodiment of the present invention will be described with reference to Figure 8. The arrow Fr in Figure 8 indicates the front of the outboard motor 81. Of the components of the outboard motor 81, all components except the drive shaft 83 and the planetary mechanism 84 are the same as in the first embodiment. That is, the second embodiment is an embodiment in which the drive shaft 83 and the planetary mechanism 84 are added to the first embodiment. For this reason, the same reference numerals as in the first embodiment are used for these components, and their descriptions are omitted.

[0073] <Drive Shaft 83> The drive shaft 83 extends vertically along the rotation axis X1. The drive shaft 83 has an upper shaft 86 and a lower shaft 87 which is positioned below the upper shaft 86 and coaxial with the upper shaft 86. The upper end of the upper shaft 86 is fixed to the first motor shaft 35 of the first motor 12. This allows the upper shaft 86 to rotate integrally with the first motor shaft 35 of the first motor 12. The lower shaft 87 is rotatably mounted relative to the upper shaft 86. The lower end of the lower shaft 87 is fixed to the first bevel gear 55 of the bevel gear mechanism 16.

[0074] <Planetary Mechanism 84> The planetary mechanism 84 is provided on the first drive force transmission path R1 between the first motor 12 and the thruster 14, and on the second drive force transmission path R2 between the second motor 17 and the lower case 13. The planetary mechanism 84 is housed in the upper case 11. The planetary mechanism 84 is positioned above the gear shift mechanism 63. The planetary mechanism 84 is, for example, a planetary type. In other embodiments, the planetary mechanism 84 may be of a type other than a planetary type (for example, a solar type or a star type).

[0075] The planetary mechanism 84 rotates at high speed when the ship 3 is propelled. Therefore, if the planetary mechanism 84 is placed in the oil, it will have a significant agitation effect on the oil. Taking this into consideration, the planetary mechanism 84 is positioned above the oil level (hereinafter referred to as the "oil level"). The planetary mechanism 84 is lubricated by oil supplied from an oil passage (not shown) provided in the upper shaft 86. The oil supplied to the planetary mechanism 84 is discharged from a discharge hole (not shown) of the planetary mechanism 84.

[0076] There are two types of oil levels: the dynamic oil level and the static oil level. When the outboard motor 81 is running, the oil level drops as the oil circulates. This oil level during operation of the outboard motor 81 is the dynamic oil level. Because the dynamic oil level fluctuates drastically, it is treated as a virtual oil level. On the other hand, when the outboard motor 81 stops, the oil level rises as the circulating oil returns. This oil level when the outboard motor 81 is stopped is the static oil level.

[0077] The planetary mechanism 84 includes a sun gear 89 (an example of a sun rotating body), a plurality of planetary gears 90 (an example of a planetary rotating body: also called a planetary pinion) that engage with the sun gear 89, a carrier 91 (an example of a carrier rotating body) that rotatably supports the plurality of planetary gears 90, and a ring gear 92 (an example of a ring rotating body) that engages with the plurality of planetary gears 90. The plurality of planetary gears 90 are arranged in groups of three at 120-degree intervals in the circumferential direction with respect to the rotation axis X1. The ring gear 92 is also called an internal gear.

[0078] The sun gear 89 is fixed to the lower part of the upper shaft 86 and is rotatably mounted integrally with the upper shaft 86. Multiple planetary gears 90 are arranged to transmit power between the sun gear 89 and the ring gear 92. The carrier 91 supports the multiple planetary gears 90 so that they can rotate and revolve. The carrier 91 is fixed to the upper end of the lower shaft 87 and is rotatably mounted integrally with the lower shaft 87. The ring gear 92 is fixed to the inner circumference of the rotating body 62 and is rotatably mounted integrally with the rotating body 62.

[0079] <Speed ​​Transmission Mechanism 63> The speed transmission mechanism 63 is provided on the second drive force transmission path R2 between the second motor 17 and the lower case 13. The speed transmission mechanism 63 is another planetary mechanism having a sun gear 70 (an example of another sun rotating body), a ring gear 73 (an example of another ring rotating body), a plurality of planetary gears 71 (an example of another planetary rotating body) arranged to transmit power between the sun gear 70 and the ring gear 73, and a carrier 72 (an example of another carrier rotating body) that supports the plurality of planetary gears 71 so that they can rotate and revolve. The sun gear 70 is mechanically connected to the second motor 17, the ring gear 73 is mechanically connected to the lower case 13, and the carrier 72 is provided so as not to rotate.

[0080] The gear shift mechanism 63 operates only when the ship 3 is turned, and its rotational speed and rotational amount are small. Therefore, even if the gear shift mechanism 63 is placed in the oil, the effect of agitation on the oil is small. Taking this into consideration, as described above, most of the gear shift mechanism 63 is positioned below the oil level.

[0081] <Propulsion of Ship 3> When the first motor shaft 35 of the first motor 12 rotates in the forward direction, the rotation of the first motor shaft 35 is transmitted to the upper shaft 86, causing the upper shaft 86 to rotate. The rotation of the upper shaft 86 is transmitted to the lower shaft 87 via the planetary mechanism 84, causing the lower shaft 87 to rotate. At this time, the rotation of the first motor shaft 35 is reduced by the planetary mechanism 84. The rotation of the lower shaft 87 is transmitted to the thruster 14 via the bevel gear mechanism 16, causing the thruster 14 to rotate in one direction around the rotation axis X2. This imparts a forward thrust to the ship 3, causing the ship 3 to move forward. Similarly, when the first motor shaft 35 of the first motor 12 rotates in the reverse direction, the thruster 14 rotates in the opposite direction around the rotation axis X2. This imparts a rearward thrust to the ship 3, causing the ship 3 to move backward. Furthermore, when the vessel 3 is moving straight, the ring gear 92 is essentially fixed, and the ring gear 92 rotates when the vessel 3 turns.

[0082] <Effects> The outboard motor 81 of this embodiment is equipped with a planetary mechanism 84 for reducing the rotation of the first motor 12. Therefore, it is possible to generate a large propulsion torque (torque for propelling the ship 3).

[0083] <Third Embodiment> Hereinafter, an outboard motor 100 (an example of a propulsion device) according to the third embodiment of the present invention will be described with reference to Figure 9. The arrow Fr in Figure 9 indicates the front of the outboard motor 100. Note that among the components of the outboard motor 100, the components other than the steering mechanism 101 are the same as in the second embodiment. More specifically, the third embodiment is an embodiment in which the speed change mechanism 63 of the steering mechanism 18 is omitted compared to the second embodiment. For this reason, the same reference numerals as in the second embodiment are used for these components, and their descriptions are omitted.

[0084] <Steering Mechanism 101> The steering mechanism 101 includes a worm gear set 61 and a rotating body 62, but does not include a speed change mechanism 63. Therefore, the protruding portion 68 of the rotating body 62 is not connected to the lower case 13 via the speed change mechanism 63, but is directly connected to the lower case 13. In all other respects, the configuration of the steering mechanism 101 is the same as that of the steering mechanism 18 according to the first and second embodiments.

[0085] <Rotational elements of the planetary mechanism 84 and their connection targets> Next, the rotational elements of the planetary mechanism 84 according to the second and third embodiments will be described with reference to Figures 8 to 10.

[0086] Figure 10 is a collinear diagram showing the rotational speeds of the rotating elements of the planetary mechanism 84. The planetary mechanism 84 is configured such that the rotational speeds of the three rotating elements, consisting of a sun gear 89, a ring gear 92, and a carrier 91, lie on a single straight line (hereinafter referred to as the "rotational speed line") in the collinear diagram, satisfying a collinear relationship. Of the three rotating elements, they are defined as the first rotating element, the second rotating element, and the third rotating element, starting from the left end in the order they are arranged in the collinear diagram. In the second and third embodiments, the sun gear 89 is the first rotating element, the carrier 91 is the second rotating element, and the ring gear 92 is the third rotating element. In the planetary mechanism 84, one of the first and third rotating elements, as defined in the order they are arranged in the collinear diagram, is mechanically connected to a first drive source (e.g., a first motor 12) or a second drive source (e.g., a second motor 17), the other is mechanically connected to the remaining drive source, and the second rotating element is mechanically connected to the thruster 14. The first and third rotating elements, which are mechanically connected to the second drive source, are also mechanically connected to the lower case 13, which is the steering section, via the rotating body 62 and the steering mechanism 18 or 101 (in particular, the planetary mechanism 84 provided on the second drive force transmission path R2).

[0087] The outboard motor 100 (propulsion device) comprises a first motor 12 (first drive source), a thruster 14 installed so as to rotate around a rotation axis X2 by the driving force output from the first motor 12 and to be submerged in the open water, a second motor 17 (second drive source) different from the first motor 12, a lower case 13 (rudder section) installed so as to rotate around a rotation axis X1 by the driving force output from the second motor 17, and a planetary mechanism 84 installed on a first drive force transmission path R1 between the first motor 12 and the thruster 14, and on a second drive force transmission path R2 between the second motor 17 and the lower case 13, wherein the planetary mechanism 84 comprises a sun gear 89 (sun rotor), a ring gear 92 (ring rotor), and the sun gear 89 and the ring gear 92 The system includes a plurality of planetary gears 90 (planetary rotating bodies) arranged between them to transmit power, and a carrier 91 (carrier rotating body) that supports the planetary gears 90 so that they can rotate and revolve. The system is configured such that the rotational speeds of the three rotating elements, consisting of the sun gear 89, ring gear 92, and carrier 91, lie on a single straight line in the collinear diagram, satisfying a collinear relationship. Of the three rotating elements, when arranged from left to right in the collinear diagram, they are designated as the first rotating element, the second rotating element, and the third rotating element. The first rotating element is mechanically connected to either the first motor 12 or the second motor 17, the third rotating element is mechanically connected to the other of the first motor 12 or the second motor 17, and the second rotating element is mechanically connected to the thruster 14.

[0088] In the second and third embodiments, during steering of the vessel 3 and outboard motors 81 and 100, the rotational speed of the ring gear 92 changes, which may cause the rotational speed line to shift slightly up and down around the rotational speed of the sun gear 89. However, since the time during which the rotational speed of the ring gear 92 changes (the time required for steering the vessel 3 and outboard motor 1) is short, and the amount of change in the rotational speed of the ring gear 92 is small, the influence of the vertical displacement on the gear ratio of the planetary mechanism 84 is considered to be extremely small.

[0089] Referring to Figures 8 and 9, the sun gear 89 (first rotating element) is mechanically connected to the first motor 12 via the upper shaft 86. The carrier 91 (second rotating element) is mechanically connected to the thruster 14 via the lower shaft 87 and the bevel gear mechanism 16. The ring gear 92 (third rotating element) is mechanically connected to the second motor 17 via the rotating body 62 and the worm gear set 61. In other words, the second motor 17 is connected to the ring gear 92 via the worm gear set 61.

[0090] <Operation of Worm Gear Set 61> The worm gear set 61 is a gear device composed of a worm 65 having a screw-shaped tooth profile and a worm wheel 66 that meshes with the worm 65. The worm wheel 66 is connected to a ring gear 92 via a rotating body 62. Generally, the worm gear set 61 is known to have a self-locking function that transmits driving force from the input side to the output side and suppresses the transmission of power from the output side to the input side, depending on the geometric and friction conditions. Specifically, the worm gear set 61 has a self-locking function when the tangential force Ft of the worm 65, calculated by equation (3) below, is less than zero. In equation (3) below, Fn represents the normal force of the worm gear set 61 (force acting in the direction normal to the tooth surface), "α" represents the perpendicular pressure angle of the tooth surface, "β" represents the reference cylinder lead angle, and "μ" represents the friction coefficient of the tooth surface. Ft=Fn(cosα×sinβ−μcosβ)...(3)

[0091] The worm gear set 61 is configured such that it has the self-locking function described above. In other words, the worm gear set 61 is configured such that the tangential force Ft of the worm 65 calculated by equation (3) above is less than zero. That is, the worm gear set 61 is configured to transmit the driving force transmitted from the second motor 17 to the ring gear 92, and not to transmit the power transmitted from the ring gear 92 to the second motor 17. As a result, the worm gear set 61 functions as a one-way driving force transmission unit. The worm gear set 61 substantially maintains the gear ratio of the planetary mechanism 84 by suppressing reverse drive from the ring gear 92, which is the third rotating element, to the second motor 17, even when a load is applied to the thruster 14.

[0092] In particular, in the second embodiment, when the vessel 3 is moving in a straight line, the worm gear set 61 receives differential torque (torque equivalent to the difference obtained by subtracting the product of the carrier torque and the reciprocal of the gear ratio of the gear shift mechanism 63 from the ring gear torque). When the vessel 3 is turning, the lower case 13 in the water receives resistance from the water flow and generates a moment, so the torque required for the vessel 3 to turn is the sum of the differential torque and the water flow resistance torque. For this reason, the gear ratio of the worm gear set 61 is set to overcome the sum of the differential torque and the water flow resistance torque. The worm gear set 61 is set to suppress the reverse rotation of the ring gear 92 against the differential torque when the vessel 3 is moving in a straight line, and to suppress the reverse rotation of the ring gear 92 against the sum of the differential torque and the water flow resistance torque when the vessel 3 is turning.

[0093] In the second and third embodiments, when a load is applied to the thruster 14, the bevel gear mechanism 16 generates a reaction force. This reaction force is transmitted to the lower case 13 that supports the bevel gear mechanism 16, generating a torque that attempts to rotate the lower case 13. This torque may cause the lower case 13 and the ring gear 92 to rotate unintentionally.

[0094] To suppress the rotation of the lower case 13 and ring gear 92, it is conceivable to continuously generate torque in the second motor 17 to hold the lower case 13 and ring gear 92 in a stopped state. However, if such measures are taken, the second motor 17 will continue to drive in order to hold the lower case 13 in a stopped state, which may affect the durability of the second motor 17. On the other hand, adding a mechanism (for example, a brake mechanism) to hold the lower case 13 and ring gear 92 in a stopped state may lead to increased complexity in the configuration of the outboard motors 81 and 100.

[0095] Therefore, in this embodiment, the lower case 13 and ring gear 92 are held in a stopped state by the self-locking function of the worm gear set 61. By adopting this configuration, it is possible to suppress unintended rotation of the lower case 13 and ring gear 92 without the second motor 17 having to continuously generate torque to hold the lower case 13 and ring gear 92 in a stopped state, or without adding a mechanism to hold the lower case 13 and ring gear 92 in a stopped state. This suppresses the impact on the durability of the second motor 17 and the complexity of the outboard motors 81 and 100, and also suppresses unintended rotation of the lower case 13 and ring gear 92.

[0096] <Fourth Embodiment> Hereinafter, an outboard motor 110 (an example of a propulsion device) according to the fourth embodiment of the present invention will be described with reference to Figure 11. The arrow Fr in Figure 11 indicates the front of the outboard motor 110. Note that among the components of the outboard motor 110, the components other than the connecting cylinder 111 and the speed control mechanism 112 are the same as in the third embodiment. That is, the fourth embodiment is an embodiment in which the connecting cylinder 111 and the speed control mechanism 112 are added to the third embodiment. For this reason, these components are given the same reference numerals as in the third embodiment, and their descriptions are omitted.

[0097] <Connecting Cylinder 111> The connecting cylinder 111 is positioned on the inner circumference of the rotating body 62, coaxially with the rotation axis X1. The upper end of the connecting cylinder 111 is fixed to the ring gear 92 of the planetary mechanism 84. As a result, the connecting cylinder 111 is provided to rotate integrally with the ring gear 92 of the planetary mechanism 84. Note that the ring gear 92 of the planetary mechanism 84 is not fixed to the rotating body 62, but is provided to rotate relative to the rotating body 62. The lower end of the connecting cylinder 111 is fixed to the upper end of the lower case 13. As a result, the connecting cylinder 111 is provided to rotate integrally with the lower case 13.

[0098] <Speed ​​Transmission Mechanism 112> The speed transmission mechanism 112 includes a sun gear 113, a plurality of planetary gears 114 that engage with the sun gear 113, a carrier 115 that rotatably supports the plurality of planetary gears 114, and a ring gear 116 that engages with the plurality of planetary gears 114. The ring gear 116 is also called an internal gear.

[0099] The sun gear 113 is integrally provided with the protruding portion 68 of the rotating body 62 and can rotate together with the rotating body 62. The carrier 115 is fixed to the upper case 11 and cannot rotate. The ring gear 116 is fixed to the lower part of the connecting cylinder 111 and can rotate together with the connecting cylinder 111. In the transmission mechanism 112, the sun gear 113 is the point of force application (input point of steering force), the carrier 115 is the pivot point (fixed point), and the ring gear 116 is the point of application (output point of steering force).

[0100] <Rotational elements of the planetary mechanism 84 and their connections> The sun gear 89 (first rotational element) is mechanically connected to the first motor 12 via the upper shaft 86. The carrier 91 (second rotational element) is mechanically connected to the thruster 14 via the lower shaft 87 and the bevel gear mechanism 16. The ring gear 92 (third rotational element) is mechanically connected to the second motor 17 via the connecting cylinder 111, the speed change mechanism 112, and the worm gear set 61. The ring gear 92 is also mechanically connected to the lower case 13, which is the steering section, via the connecting cylinder 111.

[0101] In this embodiment, the steering mechanism 18 includes a worm gear set 61 comprising a worm 65 driven by a second motor 17 and a worm wheel 66 engaged with the worm 65, and a speed change mechanism 112 provided in the rotational transmission path R from the worm wheel 66 to the lower case 13. By adopting this configuration, the rotation of the second motor 17 can be reduced by both the worm gear set 61 and the speed change mechanism 112. Therefore, the rotation of the second motor 17 can be significantly reduced without setting a large gear ratio for the worm gear set 61. As a result, a large steering torque can be generated without increasing the size of the worm wheel 66.

[0102] Furthermore, a gear shift mechanism 112 (secondary reduction unit) is provided downstream of the worm gear set 61 (primary reduction unit). In this configuration, if the gear ratio of the gear shift mechanism 112 is set to a non-integer multiple greater than 1, the normal engagement angle range ER of the worm wheel 66 can be changed by rotating the lower case 13 a predetermined integer number of times (see the first embodiment). This suppresses wear of the normal engagement angle range ER of the worm wheel 66 and improves the durability of the worm wheel 66.

[0103] Furthermore, in a configuration where the worm gear set 61 directly receives the carrier torque when the vessel 3 is moving in a straight line, the torque acting on the worm gear set 61 increases. In contrast, in this embodiment, when the vessel 3 is moving in a straight line, the ring gear 92 of the planetary mechanism 84 receives the carrier torque, and the worm gear set 61 receives the sun gear torque. By adopting such a configuration, the torque received by the worm gear set 61 when the vessel 3 is moving in a straight line can be reduced from the carrier torque to the sun gear torque. The worm gear set 61 is set to suppress the reverse rotation of the ring gear 92 against the sun gear torque when the vessel 3 is moving in a straight line, and to suppress the reverse rotation of the ring gear 92 against the sum of the sun gear torque and the water flow resistance torque when the vessel 3 is turning.

[0104] <Other Modifications> In the second and third embodiments described above, the unidirectional drive force transmission unit is configured by a worm gear set 61. In other embodiments, the unidirectional drive force transmission unit may be configured by a mechanism other than the worm gear set 61. For example, in other embodiments, the unidirectional drive force transmission unit may be configured by a two-way clutch. A one-way clutch is a mechanism that transmits forward rotation in one direction but not reverse rotation, and transmits reverse rotation in the other direction but not forward rotation. In contrast, a two-way clutch is a mechanism that controls the switching between a one-way clutch in one direction and a one-way clutch in the other direction. Thus, a two-way clutch is a different mechanism from a one-way clutch.

[0105] In the planetary mechanism 84 of the second and third embodiments, the sun gear 89 (first rotating element) is mechanically connected to the first motor 12, and the ring gear 92 (third rotating element) is mechanically connected to the second motor 17. In other embodiments, the first rotating element may be mechanically connected to the second motor 17, and the third rotating element may be mechanically connected to the first motor 12.

[0106] In the second and third embodiments, the planetary mechanism 84 has a plurality of planetary gears 90. In other embodiments, the planetary mechanism 84 may have first and second pinion gears that mesh with each other instead of each planetary gear 90 (pinion gear). In other words, the planetary mechanism 84 may have a so-called "double pinion structure". The first pinion gear meshes with the sun gear 89, and the second pinion gear meshes with the first pinion gear and the ring gear 92. The carrier 91 supports the first and second pinion gears so that they can rotate and revolve.

[0107] If the planetary mechanism 84 has a double pinion structure, the arrangement in the collinear diagram will be, from left to right, sun gear 89, ring gear 92, and carrier 91. In this case, the sun gear 89 (first rotating element) may be mechanically connected to the first motor 12, the ring gear 92 (second rotating element) may be mechanically connected to the thruster 14, and the carrier 91 (third rotating element) may be mechanically connected to the worm gear set 61 and the lower case 13.

[0108] In the second and third embodiments described above, the sun gear 89, the multiple planetary gears 90, and the ring gear 92 are examples of a sun rotating body, a planetary rotating body, and a ring rotating body, respectively. In other embodiments, the sun roller, the multiple planetary rollers, and the ring roller may be examples of a sun rotating body, a planetary rotating body, and a ring rotating body, respectively. In other words, the planetary mechanism 84 may be a gear system (a system that transmits rotation by the meshing of gears) or a roller system (a system that transmits rotation by the frictional force between rollers).

[0109] In the first and second embodiments described above, the gear shifting mechanism 63 has a sun gear 70, a plurality of planetary gears 71, and a ring gear 73. In other embodiments, the gear shifting mechanism 63 may have a sun roller, a plurality of planetary rollers, and a ring roller. In other words, the gear shifting mechanism 63 may be a gear system (a system that transmits rotation by the meshing of gears) or a roller system (a system that transmits rotation by the frictional force between rollers).

[0110] In the first to third embodiments, the first drive source is configured by a first motor 12 (electric motor). In other embodiments, the first drive source may be configured by a mechanism other than an electric motor (for example, an internal combustion engine).

[0111] In the first to third embodiments, the second drive source is configured by a second motor 17 (electric motor). In other embodiments, the second motor 17 may be configured by a mechanism other than an electric motor (for example, a hydraulic actuator).

[0112] In the first to third embodiments, an example of a propulsion system is an outboard motor 1, 81, 100 in which a first motor 12 (an example of a first drive source) is housed in an upper case 11. In other embodiments, an example of a propulsion system may be an inboard / outboard motor (stern drive) in which a first drive source such as a first motor 12 is installed on the ship 3.

[0113] In the first to third embodiments, the outboard motors 1, 81, and 100 are mounted on a vessel 3 (an example of a water-based mobile vehicle). In other embodiments, the propulsion devices such as the outboard motors 1, 81, and 100 may be mounted on a water mobility vehicle other than the vessel 3. For example, in other embodiments, the propulsion devices may be mounted on an underwater mobile vehicle (a mobile vehicle that is submerged and propelled). Water mobility is a general term for mobile vehicles that move on or underwater. Water mobility may also be called a marine vehicle.

[0114] <Summary of Embodiments> The propulsion devices 81, 100, and 110 each include a first drive source 12, a thruster 14 provided to rotate around a rotation axis X2 by the driving force output from the first drive source 12 and to be submerged in external water, a second drive source 17 different from the first drive source 12, a steering unit 13 provided to rotate around a rotation axis X1 by the driving force output from the second drive source 17, and a planetary mechanism 84 provided on a first drive force transmission path R1 between the first drive source 12 and the thruster 14, and on a second drive force transmission path R2 between the second drive source 17 and the steering unit 13. The planetary mechanism 84 includes a sun rotating body 89, a ring rotating body 92, and is arranged to transmit power between the sun rotating body 89 and the ring rotating body 92. The device comprises a planetary rotating body 90 and a carrier rotating body 91 that supports the planetary rotating body 90 so that it can rotate on its axis and revolve. The three rotating elements, consisting of the sun rotating body 89, the ring rotating body 92, and the carrier rotating body 91, are configured such that their rotational speeds lie on a single straight line in the collinear diagram, satisfying a collinear relationship. Of the three rotating elements, when they are arranged in the collinear diagram from left to right as the first rotating element, the second rotating element, and the third rotating element, the first rotating element is mechanically connected to either the first drive source 12 or the second drive source 17, the third rotating element is mechanically connected to either the first drive source 12 or the second drive source 17, and the second rotating element is mechanically connected to the thruster 14.

[0115] According to this embodiment, it is possible to suppress the impact on the durability of the second drive source 17 and the complexity of the configuration of the propulsion devices 81, 100, and 110, and to suppress the steering section 13 from rotating unintentionally.

[0116] The second drive source 17 may be connected to the first rotating element or the third rotating element via the unidirectional drive force transmission unit 61.

[0117] The one-way drive force transmission unit 61 may be configured to transmit the drive force transmitted from the second drive source 17 to the first rotating element or the third rotating element, and not to transmit the power transmitted from the first rotating element or the third rotating element to the second drive source 17.

[0118] The one-way drive force transmission unit 61 may be a worm gear set 61 having a worm 65 driven by the second drive source 17 and a worm wheel 66 that engages with the worm 65.

[0119] The worm gear set 61 may also be equipped with a self-locking function.

[0120] The worm wheel 66 may be connected via the rotating body 62 to one of the rotating elements, the first rotating element and the third rotating element, which is mechanically connected to the second drive source 17.

[0121] The unidirectional drive force transmission unit 61 may substantially maintain the gear ratio of the planetary mechanism 84 by suppressing reverse driving from one of the first and third rotating elements, which is mechanically connected to the second drive source 17, to the second drive source 17 when a load is applied to the thruster 14.

[0122] The one-way drive force transmission unit 61 may suppress unintended rotation of one of the first and third rotating elements, which is mechanically connected to the second drive source 17, and the steering unit 13, when a load is applied to the thruster 14, which generates torque that would cause the steering unit 13 to rotate.

[0123] The sun rotating body 89 is the first rotating element, the carrier rotating body 91 is the second rotating element, and the ring rotating body 92 is the third rotating element, wherein the first rotating element is mechanically connected to the first drive source 12, and the third rotating element is mechanically connected to the second drive source 17 via the unidirectional drive force transmission unit 61.

[0124] The propulsion device 81 may further include a gear shifting mechanism 63 provided on the second drive force transmission path R2.

[0125] The propulsion device 81 further comprises a worm gear set 61 having a worm 65 and a worm wheel 66 that engages with the worm 65, wherein the worm wheel 66 engages with the worm 65 within a predetermined normal engagement angle range ER, and the gear ratio of the transmission mechanism 63 may be set such that the normal engagement angle range ER is changed by rotating the steering section 13 a predetermined integer number of times.

[0126] The gear ratio of the transmission mechanism 63 may be set such that the normal engagement angle range ER after the steering unit 13 has been rotated an integer number of times does not overlap with the normal engagement angle range ER before the steering unit 13 has been rotated an integer number of times.

[0127] The normal engagement angle range ER includes a first engagement range E1 that includes the center angle EC of the normal engagement angle range ER, and a second engagement range E2 located outside the first engagement range E1. The gear ratio of the transmission mechanism 63 may be set such that the first engagement range E1 after the steering section 13 has been rotated an integer number of times does not overlap with the first engagement range E1 before the steering section 13 has been rotated an integer number of times, and the second engagement range E2 after the steering section 13 has been rotated an integer number of times at least partially overlaps with the second engagement range E2 before the steering section 13 has been rotated an integer number of times.

[0128] The propulsion device 81 further includes a control device 19 that controls the driving of the second drive source 17, and the control device 19 may determine whether or not predetermined range change conditions are met.

[0129] The control device 19 may, when the range change condition is met, execute a range change process to change the normal engagement angle range ER by having the second drive source 17 rotate the steering unit 13 an integer number of times.

[0130] The control device 19 may execute the range change process when the rotation of the thruster 14 has stopped and the range change conditions are met.

[0131] The propulsion device 81 further comprises a worm gear set 61 having a worm 65 and a worm wheel 66 that engages with the worm 65, and the gear ratio of the transmission mechanism 63 may be set such that the normal engagement angle range ER of the worm wheel 66 is changed by rotating the steering section 13 a predetermined integer number of times.

[0132] The gear ratio of the transmission mechanism 63 may be set to a non-integer multiple greater than 1.

[0133] The aforementioned gear shifting mechanism 63 is another planetary mechanism comprising another sun rotating body 70, another ring rotating body 73, another planetary rotating body 71 arranged to transmit power between the other sun rotating body 70 and the other ring rotating body 73, and another carrier rotating body 72 that supports the other planetary rotating body 71 so that it can rotate and revolve.

[0134] The other sun rotating body 70 is mechanically connected to the second drive source 17, the other ring rotating body 73 is mechanically connected to the steering section 13, and the other carrier rotating body 72 is provided in a non-rotatable manner.

[0135] The water mobility 3 may be equipped with the propulsion devices 81, 100, and 110.

[0136] This concludes the description of specific embodiments, but the present invention is not limited to the above embodiments or modifications and can be broadly modified and implemented.

[0137] 3: Ship (an example of water mobility) 12: First motor (an example of the first drive source) 13: Lower case (an example of the steering section) 14: Propulsion unit 17: Second motor (an example of the second drive source) 19: Control device 61: Worm gear set (an example of a one-way drive force transmission section) 62: Rotating body 63: Speed ​​change mechanism 65: Worm 66: Worm wheel 70: Sun gear (an example of another sun rotating body) 71: Planetary gear (an example of another planetary rotating body) 72: Carrier (an example of another carrier rotating body) 73: Ring gear (an example of another ring rotating body) 81: Outboard motor (an example of a propulsion device) 84: Planetary mechanism 89: Sun gear (an example of a sun rotating body) 90: Planetary gear (an example of a planetary rotating body) 91: Carrier (an example of a carrier rotating body) 92: Ring gear (an example of a ring rotating body) 100: Outboard motor (an example of a propulsion device) 110: Outboard motor (an example of a propulsion device) E1: First engagement range E2: Second engagement range EC: Engagement center angle ER: Normal engagement angle range R1: First drive force transmission path R2: Second drive force transmission path X1: Rotation axis X2: Rotation axis

Claims

1. A propulsion system comprising: a first drive source; a thruster provided to rotate around a rotation axis by a driving force output from the first drive source and to be submerged in external water; a second drive source different from the first drive source; a steering unit provided to rotate around a rotation axis by a driving force output from the second drive source; and a planetary mechanism provided on a first drive force transmission path between the first drive source and the thruster, and on a second drive force transmission path between the second drive source and the steering unit, wherein the planetary mechanism comprises: a sun rotating body; a ring rotating body; a planetary rotating body disposed between the sun rotating body and the ring rotating body so as to transmit power; and a carrier rotating body supporting the planetary rotating body so as to be able to rotate and revolve, wherein the rotational speeds of the three rotating elements consisting of the sun rotating body, the ring rotating body, and the carrier rotating body satisfy a collinear relationship in which the rotational speeds lie on a single straight line in a collinear diagram, A propulsion device in which, of the three rotating elements, in the order shown in the collinear diagram, are designated as the first rotating element, the second rotating element, and the third rotating element from left to right, the first rotating element is mechanically connected to either the first drive source or the second drive source, the third rotating element is mechanically connected to either the first drive source or the second drive source, and the second rotating element is mechanically connected to the thruster.

2. The propulsion device according to claim 1, wherein the second drive source is connected to the first rotating element or the third rotating element via a unidirectional drive force transmission unit.

3. The propulsion device according to claim 2, wherein the unidirectional drive force transmission unit is provided to transmit the drive force transmitted from the second drive source side to the first rotating element side or the third rotating element side, and not to transmit the power transmitted from the first rotating element side or the third rotating element side to the second drive source side.

4. The propulsion device according to claim 2 or 3, wherein the unidirectional drive force transmission unit is a worm gear set having a worm driven by the second drive source and a worm wheel that engages with the worm.

5. The propulsion device according to claim 4, wherein the worm gear set is equipped with a self-locking function.

6. The propulsion device according to claim 4 or 5, wherein the worm wheel is connected via a rotating body to one of the first rotating element and the third rotating element which is mechanically connected to the second drive source.

7. The propulsion device according to any one of claims 2 to 6, wherein the unidirectional drive force transmission unit substantially maintains the gear ratio of the planetary mechanism by suppressing reverse drive from one of the first and third rotating elements that is mechanically connected to the second drive source to the second drive source when a load is applied to the propulsion device.

8. The propulsion device according to any one of claims 2 to 7, wherein the unidirectional drive force transmission unit suppresses unintended rotation of one of the first and third rotating elements that is mechanically connected to the second drive source and the steering unit when a load is applied to the propulsion device and torque is generated that would cause the steering unit to rotate.

9. The propulsion device according to any one of claims 2 to 8, wherein the sun rotating body is the first rotating element, the carrier rotating body is the second rotating element, and the ring rotating body is the third rotating element, the first rotating element is mechanically connected to the first drive source, and the third rotating element is mechanically connected to the second drive source via the unidirectional drive force transmission unit.

10. The propulsion device according to any one of claims 1 to 9, further comprising a gear shifting mechanism provided on the second drive force transmission path.

11. The propulsion device according to claim 10, further comprising a worm gear set having a worm and a worm wheel that engages with the worm, wherein the worm wheel engages with the worm within a predetermined normal engagement angle range, and the gear ratio of the gear shift mechanism is set such that the normal engagement angle range is changed by rotating the steering part a predetermined integer number of times.

12. The propulsion device according to claim 11, wherein the gear ratio of the transmission mechanism is set such that the normal engagement angle range after the steering section has been rotated an integer number of times does not overlap with the normal engagement angle range before the steering section has been rotated an integer number of times.

13. The propulsion device according to claim 11, wherein the normal engagement angle range includes a first engagement range that includes the center angle of the normal engagement angle range, and a second engagement range located outside the first engagement range, and the gear ratio of the gear shift mechanism is set such that the first engagement range after the steering unit has been rotated an integer number of times does not overlap with the first engagement range before the steering unit has been rotated an integer number of times, and the second engagement range after the steering unit has been rotated an integer number of times at least partially overlaps with the second engagement range before the steering unit has been rotated an integer number of times.

14. The propulsion device according to any one of claims 11 to 13, further comprising a control device for controlling the drive of the second drive source, wherein the control device determines whether or not a predetermined range change condition is met.

15. The propulsion device according to claim 14, wherein the control device performs a range change process to change the normal engagement angle range by causing the second drive source to rotate the steering unit an integer number of times when the range change condition is met.

16. The propulsion device according to claim 15, wherein the control device executes the range change process when the rotation of the propulsion device has stopped and the range change condition is met.

17. A propulsion device according to any one of claims 10 to 16, further comprising a worm gear set having a worm and a worm wheel that engages with the worm, wherein the gear ratio of the gear mechanism is set such that the normal engagement angle range of the worm wheel is changed by rotating the steering portion a predetermined integer number of times.

18. The propulsion device according to any one of claims 10 to 17, wherein the gear ratio of the transmission mechanism is set to a non-integer multiple greater than 1.

19. The propulsion device according to any one of claims 10 to 18, wherein the gear shifting mechanism is another planetary mechanism comprising another sun rotating body, another ring rotating body, another planetary rotating body disposed between the other sun rotating body and the other ring rotating body so as to transmit power, and another carrier rotating body that supports the other planetary rotating body so as to rotate and revolve.

20. The propulsion device according to claim 19, wherein the other sun rotating body is mechanically connected to the second drive source, the other ring rotating body is mechanically connected to the steering section, and the other carrier rotating body is provided in a non-rotatable manner.

21. A water mobility device equipped with the propulsion device described in any one of claims 1 to 20.

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