Ship propulsion systems and ships

Abstract

Reduce rattle noise from ship propulsion systems. [Solution] The ship's propulsion system comprises an engine, a propeller shaft, a transmission mechanism, a cover, a shoe pin, a shoe, and an elastic body. The transmission mechanism has a drive gear that rotates by the engine's driving force and a driven gear that meshes with the drive gear. The cover covers the outer circumference of the propeller shaft. The shoe pin is positioned between the propeller shaft and the cover. The shoe pin rotates around the propeller shaft as the propeller shaft rotates. The shoe is attached to the shoe pin and rotates around the shoe pin. The shoe has a first part located on one side in a direction intersecting the radial direction of the propeller shaft with respect to the shoe pin, and a second part located on the other side in a direction intersecting the radial direction of the propeller shaft with respect to the shoe pin. The center of gravity of the shoe is located in the first part. The elastic body biases the second part and the cover to contact each other.

Description

Technical Field

[0001] The technology disclosed in this specification relates to a marine propulsion unit and a ship.

Background Art

[0002] Known marine propulsion units include an engine, an output shaft, an input pinion that rotates by the driving force of the engine, a forward gear and a reverse gear that mesh with the input pinion, and an actuator. The actuator reduces rattle noise by braking the forward gear or the reverse gear. The driving method of the actuator is electric, hydraulic or pneumatic (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] There was room for improvement in reducing the rattle noise of marine propulsion units.

[0005] This specification discloses a technology capable of solving the above problems.

Means for Solving the Problems

[0006] The technology disclosed in this specification can be realized, for example, in the following forms.

[0007] (1) A ship propulsion system disclosed herein comprises an engine, a propeller shaft, a transmission mechanism, a cover, a shoe pin, a shoe, and an elastic body. The transmission mechanism transmits the driving force of the engine to the propeller shaft. The transmission mechanism has a drive gear that rotates by the driving force of the engine and a driven gear that meshes with the drive gear. The cover covers the outer circumference of the propeller shaft. The shoe pin is positioned between the propeller shaft and the cover. The shoe pin rotates around the propeller shaft in conjunction with the rotation of the propeller shaft. The shoe is attached to the shoe pin and rotates around the shoe pin. The shoe has a first portion located on one side in a direction intersecting the radial direction of the propeller shaft with respect to the shoe pin, and a second portion located on the other side in a direction intersecting the radial direction of the propeller shaft with respect to the shoe pin. The center of gravity of the shoe is located in the first portion. The elastic body biases the second portion and the cover so that they come into contact with each other.

[0008] According to this ship propulsion system, rattle noise can be reduced by applying friction to the propeller shaft through the action of an elastic body, and the friction applied to the propeller shaft can be attenuated as the rotational speed of the propeller shaft increases.

[0009] (2) Other marine propulsion systems disclosed herein include an engine, a shaft, a transmission mechanism, a cover, a shoe pin, a shoe, and an elastic body. The transmission mechanism transmits the driving force of the engine to the shaft. The transmission mechanism includes a drive gear that rotates with respect to the driving force of the engine, and a driven gear that meshes with the drive gear. The cover covers the outer circumference of the shaft. The shoe pin is positioned between the shaft and the cover. The shoe pin rotates around the shaft as the shaft rotates. The shoe is attached to the shoe pin and rotates around the shoe pin. The shoe has a first portion located on one side of the shoe pin in a direction intersecting the radial direction of the shaft, and a second portion located on the other side of the shoe pin in a direction intersecting the radial direction of the shaft. The center of gravity of the shoe is located in the first portion. The elastic body biases the second portion and the cover to contact each other.

[0010] According to this ship propulsion system, rattle noise can be reduced by applying friction to the shaft through the action of an elastic body, and the friction applied to the shaft can be dampened as the rotational speed of the shaft increases.

[0011] Furthermore, the technologies disclosed herein can be implemented in various forms, for example, in the form of a ship propulsion system, a ship equipped with a ship propulsion system and a hull, and so on. [Effects of the Invention]

[0012] According to this ship propulsion system, rattle noise can be reduced by applying friction to the shaft through the action of an elastic body, and the friction applied to the shaft can be dampened as the rotational speed of the shaft increases. [Brief explanation of the drawing]

[0013] [Figure 1] A perspective view illustrating the ship's configuration. [Figure 2] A schematic side view showing the configuration of the outboard motor. [Figure 3] Diagram illustrating the detailed configuration around the propeller shaft. [Figure 4] An explanatory diagram showing an enlarged portion of Figure 3. [Figure 5] Figure 3 is an explanatory diagram showing a cross-section of the outboard motor at position VV. [Figure 6] A diagram illustrating the detailed configuration around the shoe when the engine body is rotating at a relatively low speed. [Figure 7] A diagram illustrating the detailed configuration around the shoe when the engine body is rotating at a relatively high speed. [Modes for carrying out the invention]

[0014] A. Embodiments: (Composition of ship 10) Figure 1 is a schematic perspective view showing the configuration of the vessel 10. Figure 1 and other drawings described later show arrows indicating directions relative to the position of the vessel 10. Each figure shows arrows indicating the front, rear, left, right, up, and down directions. The longitudinal, left-right, and up-down directions are all orthogonal to each other. Note that axes and members extending in the longitudinal direction in this specification do not necessarily have to be parallel to the longitudinal direction. Axes and members extending in the longitudinal direction include axes and members inclined within a range of ±45° with respect to the longitudinal direction. Similarly, axes and members extending in the up-down direction include axes and members inclined within a range of ±45° with respect to the up-down direction, and axes and members extending in the left-right direction include axes and members inclined within a range of ±45° with respect to the left-right direction.

[0015] The vessel 10 comprises a hull 200 and an outboard motor 100. In this embodiment, the vessel 10 is equipped with one outboard motor 100, but the vessel 10 may be equipped with multiple outboard motors 100.

[0016] (Construction of the hull 200) The hull 200 is the part where the crew of the ship 10 boards. The hull 200 has a hull main body 202, a steering station 240, and a steering device 250. A living space 204 is formed in the hull main body 202. The steering station 240 is installed in the living space 204. The steering device 250 is installed near the steering station 240. The steering device 250 is a device for ship operation. The steering device 250 has, for example, a steering wheel 252, a shift throttle lever 254, a monitor 256, and an input device 258. Further, the hull 200 has a partition wall 220 and a transom 210. The partition wall 220 partitions the rear end of the living space 204. The transom 210 is located at the rear end of the hull 200. In the front-rear direction, there is a space 206 between the transom 210 and the partition wall 220.

[0017] (Configuration of the outboard motor 100) FIG. 2 is a side view schematically showing the configuration of the outboard motor 100. Hereinafter, unless otherwise specified, the outboard motor 100 in the reference posture will be described. The reference posture is a posture in which the rotation axis Ac of the crankshaft 123 described later extends in the vertical direction and the rotation axis Ap of the propeller shaft 136 described later extends in the front-rear direction. Each of the front-rear direction, the left-right direction, and the vertical direction is defined based on the outboard motor 100 in the reference posture. The outboard motor 100 is an example of a ship propulsion device.

[0018] The outboard motor 100 is a device that generates thrust to propel the ship 10. The outboard motor 100 is attached to the transom 210 at the rear of the hull 200. The outboard motor 100 has an outboard motor main body 110 and a suspension device 150.

[0019] (Configuration of the outboard motor main body 110) The outboard motor main body 110 includes an engine assembly 120, a cowl 112, a casing 116, a drive shaft 132, a propeller shaft 136, a propeller 111, a transmission mechanism 140, a silencing device 300, and a housing 340.

[0020] The engine assembly 120 is a collection of several parts, including the engine body 122. In addition to the engine body 122, the engine assembly 120 includes intake system components 126 (e.g., throttle body, supercharger, etc.) and electrical components 128 (e.g., fuse box, ECU, steering CU, etc.). The engine assembly 120 is located relatively high up in the outboard motor 100.

[0021] The engine body 122 is a prime mover that generates power. The engine body 122 is, for example, an internal combustion engine. The engine body 122 has a crankshaft 123 that converts the reciprocating motion of a piston (not shown) into rotational motion. The crankshaft 123 is positioned such that its axis of rotation Ac extends in the vertical direction. The crankshaft 123 has journals 124 and splines 125. The journals 124 support the crankshaft 123 itself at the bearing portion of the crankcase (not shown). The splines 125 are locations where multiple longitudinal grooves are formed for connection with the drive shaft 132.

[0022] The cowl 112 is a housing located on top of the outboard motor body 110. The cowl 112 has an upper cowl 113 and a lower cowl 114. The upper cowl 113 constitutes the upper part of the cowl 112. The lower cowl 114 constitutes the lower part of the cowl 112. The upper cowl 113 is detachably attached to the lower cowl 114. The cowl 112 houses at least a portion of the engine assembly 120.

[0023] The casing 116 is a housing located at the bottom of the outboard motor body 110. The casing 116 is located below the cowl 112. The casing 116 has an upper case 117 and a lower case 118. The upper case 117 constitutes the upper part of the casing 116. The lower case 118 constitutes the lower part of the casing 116.

[0024] The drive shaft 132 is a rod-shaped member that extends vertically. The upper end of the drive shaft 132 is connected to a spline 125 in the engine body 122. The drive shaft 132 extends downward from the connection point with the spline 125. The drive shaft 132 rotates together with the crankshaft 123 due to the driving force of the engine body 122. At least a portion of the drive shaft 132 is housed in the casing 116.

[0025] The propeller shaft 136 is a rod-shaped component. The propeller shaft 136 is positioned relatively below the outboard motor body 110, with its rotation axis Ap extending in the longitudinal direction. The front end of the propeller shaft 136 is housed in the lower case 118. The rear end of the propeller shaft 136 protrudes rearward from the lower case 118. The propeller shaft 136 is an example of a shaft.

[0026] The propeller 111 is a rotating body having multiple blades. The propeller 111 is attached to the rear end of the propeller shaft 136. The propeller 111 rotates together with the propeller shaft 136. The propeller 111 generates thrust for the ship 10 by rotating.

[0027] The transmission mechanism 140 is a mechanism that transmits the driving force of the engine body 122 to the propeller shaft 136. The transmission mechanism 140 includes a first gear 141, a second gear 142, a third gear 143, and a dog clutch 145. The first gear 141 is an example of a drive gear. The second gear 142 and the third gear 143 are examples of driven gears.

[0028] The first gear 141 is connected to the lower end of the drive shaft 132. The first gear 141 rotates together with the drive shaft 132 due to the driving force of the engine body 122. The axis of rotation of the first gear 141 is parallel to the axis of rotation Ac of the crankshaft 123. In other words, the axis of rotation of the first gear 141 is parallel in the vertical direction.

[0029] The second gear 142 and the third gear 143 are tubular gears that surround the front end of the propeller shaft 136. The rotation axes of the second gear 142 and the third gear 143 are parallel to the rotation axis Ap of the propeller shaft 136. In other words, the rotation axes of the second gear 142 and the third gear 143 are parallel to the horizontal direction and perpendicular to the rotation axis of the first gear 141. Each of the second gear 142 and the third gear 143 meshes with the first gear 141. As a result, the driving force of the engine body 122 is transmitted to the second gear 142 and the third gear 143 via the first gear 141.

[0030] The dog clutch 145 is positioned between the second gear 142 and the third gear 143 in the longitudinal direction. The dog clutch 145 is tubular and surrounds the front end of the propeller shaft 136. The dog clutch 145 is connected to the propeller shaft 136, for example, by a spline. The dog clutch 145 rotates together with the propeller shaft 136.

[0031] The dog clutch 145 is movable in the forward and backward directions. More specifically, the dog clutch 145 is movable between a first engagement position in which it is connected to the second gear 142, a second engagement position in which it is connected to the third gear 143, and a disengagement position in which it is separated from the second gear 142 and the third gear 143. When the dog clutch 145 is in the first engagement position, the rotation of the second gear 142 is transmitted to the dog clutch 145, and the rotation of the dog clutch 145 is transmitted to the propeller shaft 136. This causes the propeller 111 to rotate in a direction that moves the vessel 10 forward. When the dog clutch 145 is in the second engagement position, the rotation of the third gear 143 is transmitted to the dog clutch 145, and the rotation of the dog clutch 145 is transmitted to the propeller shaft 136. This causes the propeller 111 to rotate in a direction that moves the vessel 10 backward. When the dog clutch 145 is in the disengaged position, the rotation of the first gear 141 and the second gear 142 is not transmitted to the dog clutch 145. As a result, the propeller 111 does not receive the driving force of the engine body 122. In other words, when the dog clutch 145 is in the disengaged position, the outboard motor 100 is in a neutral state.

[0032] The silencer 300 and housing 340 are located relatively low down on the outboard motor 100. The silencer 300 and housing 340 are housed in the lower case 118. Details of the silencer 300 and housing 340 will be described later.

[0033] (Configuration of suspension system 150) The suspension system 150 is a device for suspending the outboard motor body 110 from the hull 200. The suspension system 150 includes a pair of left and right clamp brackets 152, a tilt shaft 154, and a swivel bracket 156.

[0034] A pair of left and right clamp brackets 152 are positioned at the rear of the hull 200, spaced apart from each other in the left-right direction, and are fixed to the transom 210 of the hull 200, for example, by bolts. Each clamp bracket 152 has a cylindrical support portion 153 with a through hole extending in the left-right direction.

[0035] The tilt shaft 154 is a rod-shaped body and is rotatably supported within a through-hole in the support portion 153 of the clamp bracket 152. The tilt axis line At, which is the center line of the tilt shaft 154, constitutes the horizontal (left-right) axis in the tilt operation of the outboard motor 100.

[0036] The swivel bracket 156 is positioned between a pair of clamp brackets 152 and is supported by a support portion 153 of the clamp brackets 152 via a tilt axis 154 so as to be rotatable around the tilt axis At. The swivel bracket 156 is rotationally driven around the tilt axis At relative to the clamp brackets 152 by a tilt device (not shown) including an actuator such as a hydraulic cylinder.

[0037] When the swivel bracket 156 rotates around the tilt axis At relative to the clamp bracket 152, the outboard motor body 110 supported by the swivel bracket 156 also rotates around the tilt axis At. This enables a tilt operation that rotates the outboard motor body 110 vertically relative to the hull 200. The tilt operation of the outboard motor 100 allows the angle of the outboard motor body 110 around the tilt axis At to be changed within a range from a tilt-down state where the propeller 111 is submerged (the outboard motor 100 is in its standard position) to a tilt-up state where the propeller 111 is above the water surface. Furthermore, a trim operation can be performed to adjust the attitude of the vessel 10 while it is running by adjusting the angle of the outboard motor body 110 around the tilt axis At.

[0038] (Detailed configuration around propeller shaft 136) Figure 3 is an explanatory diagram showing a detailed configuration around the propeller shaft 136. Figure 4 is an explanatory diagram showing an enlarged portion of Figure 3. Figure 5 is an explanatory diagram showing a cross-section of the outboard motor 100 at position VV in Figure 3. Figure 6 is an explanatory diagram showing a detailed configuration around the shoe 316 when the rotational speed of the engine body 122 is relatively low. Figures 3 and 4 show a cross-section of the outboard motor 100 perpendicular to the left-right direction. Figures 5 and 6 show a cross-section of the outboard motor 100 perpendicular to the front-rear direction. In Figures 5 and 6, the rotational directions of the propeller shaft 136 are shown as a first rotational direction RD1 and a second rotational direction RD2. The first rotational direction RD1 is the clockwise direction when viewed from the front, and the second rotational direction RD2 is the counterclockwise direction when viewed from the front.

[0039] The silencing device 300 is an assembly of components arranged around the propeller shaft 136. As will be described later, the silencing device 300 reduces rattle noise generated between the first gear 141 and the second gear 142, and rattle noise generated between the first gear 141 and the third gear 143, by applying friction to the propeller shaft 136. The housing 340 is a housing that accommodates the silencing device 300. In this embodiment, oil is stored inside the housing 340. The housing 340 is an example of a case.

[0040] The silencing device 300 comprises a cover 302, a key 310, a base 312, a shoe pin 314, a shoe 316, a torsion spring 320, a stopper 324, a shoe plate 326, a thrust washer 328, and a clip 330.

[0041] The cover 302 is a tubular member that extends in the front-rear direction. The cover 302 covers the outer circumference of the propeller shaft 136. The shape of the inner circumferential surface 302S of the cover 302 in an axial view of the propeller shaft 136 is circular.

[0042] The key 310 is a prismatic member extending in the longitudinal direction. The key 310 is positioned between the propeller shaft 136 and the cover 302 in the radial direction of the propeller shaft 136. The key 310 is connected to a portion of the radially facing surface of the propeller shaft 136. The key 310 rotates together with the propeller shaft 136. In this embodiment, the outboard motor 100 includes two keys 310 positioned at different locations relative to each other in the rotational direction of the propeller shaft 136.

[0043] The base 312 is a component with a hole 312H1 formed in the center. The base 312 is positioned between the propeller shaft 136 and the cover 302 in the radial direction of the propeller shaft 136. The propeller shaft 136 is positioned in the hole 312H1 of the base 312. The base 312 surrounds the propeller shaft 136. A portion of the surface of the base 312 facing the hole 312H1 is connected to the key 310. As the propeller shaft 136 rotates, the base 312 rotates together with the key 310 around the propeller shaft 136. The base 312 further has holes 312H2 and 312H3 formed between the hole 312H1 in the radial direction of the propeller shaft 136 and the outer edge of the base 312. In this embodiment, the base 312 is formed with three holes 312H2 that are positioned differently from each other in the rotational direction of the propeller shaft 136, and three holes 312H3 that are positioned differently from each other in the rotational direction of the propeller shaft 136.

[0044] The shoe pin 314 is a rod-shaped member extending in the front-rear direction. In this embodiment, the outboard motor 100 includes three shoe pins 314 positioned at different locations relative to each other in the rotational direction of the propeller shaft 136. The shoe pins 314 are positioned between the propeller shaft 136 and the cover 302. The front end of each shoe pin 314 is inserted into a hole 312H2 in the base 312. The shoe pin 314 is connected to the surface of the base 312 facing the hole 312H2. As the propeller shaft 136 rotates, the shoe pin 314 rotates together with the base 312 around the propeller shaft 136.

[0045] The shoe 316 is a member that extends in the rotational direction of the propeller shaft 136 when viewed in the front-rear direction. The shoe 316 is positioned between the propeller shaft 136 and the cover 302 in the radial direction of the propeller shaft 136. In this embodiment, the outboard motor 100 includes three shoes 316 that are positioned at different locations from each other in the rotational direction of the propeller shaft 136. The three shoes 316 are arranged at equal intervals in the rotational direction of the propeller shaft 136.

[0046] The shoe 316 has a hole 316H1 formed near the center in the rotational direction of the propeller shaft 136, and a hole 316H2 formed at the end of the shoe 316 relative to hole 316H1 on the first rotational direction RD1 side in the rotational direction of the propeller shaft 136. A shoe pin 314 is inserted into hole 316H1 of the shoe 316. The shoe 316 is attached to the shoe pin 314. As the propeller shaft 136 rotates, the shoe 316 rotates together with the shoe pin 314 around the propeller shaft 136. The shoe 316 also rotates around the shoe pin 314. The axis of rotation As of the shoe 316 around the shoe pin 314 coincides with the central axis of the shoe pin 314. The axis of rotation As of the shoe 316 is parallel to the axis of rotation Ap of the propeller shaft 136.

[0047] The configuration of the shoe 316 will be explained in detail using Figure 6. The shoe 316 has a first part 317 and a second part 318. The first part 317 is the part located on one side of the direction (circumferential direction) that intersects the radial direction of the propeller shaft 136 with respect to the central axis of the shoe pin 314 when the outboard motor 100 is stopped. More specifically, the first part 317 is the part located on the first rotational direction RD1 side with respect to the central axis of the shoe pin 314 when the outboard motor 100 is stopped. The second part 318 is the part located on the other side of the direction (circumferential direction) that intersects the radial direction of the propeller shaft 136 with respect to the central axis of the shoe pin 314 when the outboard motor 100 is stopped. More specifically, the second part 318 is the part located on the second rotational direction RD2 side with respect to the central axis of the shoe pin 314 when the outboard motor 100 is stopped. The shoe 316 is positioned in the radial direction of the propeller shaft 136 so that the second portion 318 can contact the cover 302 as the shoe 316 rotates around the shoe pin 314.

[0048] The center of gravity CG of the shoe 316 is located in the first part 317. In this embodiment, the shoe 316 contains a first metal and a second metal having a lower specific gravity than the first metal. The first metal is, for example, iron, and the second metal is, for example, aluminum. The first metal is present in greater quantities in the first part 317 than in the second part 318. In other words, in this embodiment, the center of gravity CG of the shoe 316 is located in the first part 317 because the first metal, which has a relatively higher specific gravity, is present in greater quantities in the first part 317 than in the second part 318.

[0049] A friction material 319 is provided on the second portion 318 of the shoe 316. The friction material 319 is provided on the surface of the second portion 318 that faces radially outward from the propeller shaft 136. The friction material 319 is provided at the location of the second portion 318 that contacts the cover 302. In other words, the outer circumferential surface 319S of the friction material 319 is the contact surface with the cover 302. The shape of the outer circumferential surface 319S of the friction material 319 in an axial view of the propeller shaft 136 is arc-shaped.

[0050] The torsion spring 320 is wound around the shoe pin 314. The torsion spring 320 is a coiled component. The central axis of the torsion spring 320 coincides with the central axis of the shoe pin 314 and the axis of rotation As. The first end E1 of the torsion spring 320 is inserted into the hole 316H2 of the shoe 316. The first end E1 of the torsion spring 320 is connected to the first part 317 of the shoe 316. The second end E2 of the torsion spring 320 is inserted into the hole 312H3. The second end E2 of the torsion spring 320 is connected to the base 312. In other words, the second end E2 of the torsion spring 320 is connected to other parts of the outboard motor 100 that rotate around the propeller shaft 136 together with the shoe pin 314. The torsion spring 320 is an example of an elastic body.

[0051] The stopper 324 is attached to the base 312. The base 312 is positioned radially on the propeller shaft 136 between the first portion 317 of the shoe 316 and the cover 302.

[0052] The shoe plate 326 is a plate with a hole 326H1 formed in the center. The hole 326H1 of the shoe plate 326 surrounds the propeller shaft 136. The shoe plate 326 has a hole 326H2 formed between the hole 326H1 and the outer edge of the shoe plate 326. In this embodiment, the shoe plate 326 has three holes 326H2 formed at equal intervals from each other in the rotational direction of the propeller shaft 136. The rear end of the shoe pin 314 is inserted into the hole 326H2 of the shoe plate 326. The surface of the shoe plate 326 facing the hole 326H2 is connected to the shoe pin 314.

[0053] The thrust washer 328 is positioned between the shoe plate 326 and the housing 340 in the front-rear direction. The thrust washer 328 is in contact with the shoe plate 326. Because the shoe plate 326 is in contact with the thrust washer 328, friction is reduced when it rotates in conjunction with the rotation of the propeller shaft 136.

[0054] The clip 330 is positioned behind the shoe plate 326. The clip 330 is in contact with both the shoe pin 314 and the shoe plate 326, securing the shoe pin 314 to the shoe plate 326.

[0055] (Operation of the silencer 300) Figure 7 is an explanatory diagram showing the detailed configuration around the shoe 316 when the engine body 122 is rotating at a relatively high speed. The operation of the silencer 300 will be explained in detail using Figures 6 and 7.

[0056] First, using Figure 6, the operation of the silencer 300 when the rotational speed of the engine body 122 is relatively low will be explained. An elastic force acts on the torsion spring 320 that brings the first end E1 and the second end E2 closer together. More specifically, an elastic force F1 acts on the first end E1 of the torsion spring 320 in a clockwise direction with respect to the central axis of the torsion spring 320 (i.e., the axis of rotation As). An elastic force F2 acts on the second end E2 of the torsion spring 320 in a counterclockwise direction with respect to the central axis of the torsion spring 320.

[0057] Furthermore, as described above, the second end E2 of the torsion spring 320 is connected to the hole 312H3 of the base 312, and the first end E1 of the torsion spring 320 is connected to the hole 316H2 of the shoe 316. Therefore, the torsion spring 320 generates a moment that causes the shoe 316 to rotate counterclockwise around the central axis of the shoe pin 314, due to the elastic force F1 acting on the first end E1. In other words, the torsion spring 320 biases the second part 318 of the shoe 316 and the cover 302 to come into contact with each other. As a result, for example, when the rotational speed of the engine body 122 is relatively low, when the engine body 122 is not rotating, or when the rotation of the engine body 122 is not transmitted to the propeller shaft 136 (i.e., in a neutral state), the friction material 319 of the second part 318 comes into contact with the cover 302. The shoe 316 applies friction to the propeller shaft 136 by pressing its second portion 318 against the cover 302.

[0058] The outboard motor 100 is prone to rattling noise when the rotational speed of the engine body 122 is relatively low. Specifically, for example, when the rotational speed of the first gear 141 fluctuates due to fluctuations in the rotational speed of the engine body 122, the rotational speeds of the second gear 142 and the third gear 143 cannot keep up with the rotational speed of the first gear 141. This causes contact between the tooth surfaces of the first gear 141 and the second gear 142, and between the first gear 141 and the third gear 143, resulting in rattling noise. In the outboard motor 100 of this embodiment, friction is applied to the propeller shaft 136 when the rotational speed of the engine body 122 is relatively low, making it easier for the rotational speeds of the second gear 142 and the third gear 143 to keep up with the rotational speed of the first gear 141. As a result, rattling noise generated between the first gear 141 and the second gear 142, and between the first gear 141 and the third gear 143 is reduced.

[0059] Next, using Figure 7, the operation of the silencer 300 when the rotational speed of the engine body 122 is relatively high will be explained. Similar to the state when the rotational speed of the engine body 122 is relatively low, an elastic force F1 acts on the first end E1 of the torsion spring 320 in a clockwise direction with respect to the central axis of the torsion spring 320, and an elastic force F2 acts on the second end E2 of the torsion spring 320 in a counterclockwise direction with respect to the central axis of the torsion spring 320. Therefore, even when the rotational speed of the engine body 122 is relatively high, the torsion spring 320 generates a moment that causes the shoe 316 to rotate counterclockwise around the central axis of the shoe pin 314, due to the elastic force F1 acting on the first end E1.

[0060] As mentioned above, the shoe 316 rotates around the propeller shaft 136 together with the shoe pin 314 as the propeller shaft 136 rotates. Therefore, the shoe 316 is subjected to a centrifugal force F3 generated as a result of the rotation of the propeller shaft 136. Note that the centrifugal force F3 refers not only to the centrifugal force acting on the first part 317 of the shoe 316, but also to the centrifugal force acting on the entire shoe 316, including the second part 318. As mentioned above, the shoe 316 rotates around the shoe pin 314. The center of gravity CG of the shoe 316 is located at the first part 317. Therefore, when the shoe 316 is subjected to the centrifugal force F3 generated as a result of the rotation of the propeller shaft 136, a moment is generated that causes the shoe 316 to rotate clockwise around the central axis of the shoe pin 314. When the moment generated by the centrifugal force F3 that rotates the shoe 316 clockwise around the central axis of the shoe pin 314 exceeds the moment generated by the elastic force F1 that rotates the shoe 316 counterclockwise around the central axis of the shoe pin 314, the first part 317 is displaced so as to be radially outward of the propeller shaft 136. In other words, when the rotational speed of the propeller shaft 136 exceeds a certain value, the friction material 319 of the second part 318 separates from the cover 302. When the friction material 319 separates from the cover 302, the entire outer surface 319S separates from the cover 302 at the same time.

[0061] The outboard motor 100 is less prone to rattling noise when the rotational speed of the engine body 122 is relatively high. In the outboard motor 100 of this embodiment, the friction applied to the propeller shaft 136 is reduced when the rotational speed of the propeller shaft 136 exceeds a certain value, thereby reducing the generation of rattling noise and attenuating the friction applied to the propeller shaft 136 as the rotational speed of the propeller shaft 136 increases.

[0062] The rotational speed of the engine body 122 when the second portion 318 of the shoe 316 separates from the cover 302 can be set to any value by adjusting, for example, the mass of the shoe 316, the position of the center of gravity CG of the shoe 316, etc. In this embodiment, the second portion 318 of the shoe 316 contacts the cover 302 when the rotational speed of the engine body 122 is less than or equal to the trolling rotational speed, and separates from the cover 302 when the rotational speed of the engine body 122 is greater than the trolling rotational speed.

[0063] Furthermore, a stopper 324 is positioned between the first portion 317 of the shoe 316 and the cover 302. Therefore, in this embodiment, when the rotational speed of the engine body 122 is equal to or greater than the trolling rotational speed, no portion of the shoe 316 comes into contact with the cover 302.

[0064] B. Variations: The technologies disclosed herein are not limited to the embodiments described above and can be modified in various forms without departing from their essence, for example, the following modifications are possible.

[0065] The configurations of the ship 10 and the outboard motor 100 in the above embodiment are merely examples and can be modified in various ways. For example, in the above embodiment, an outboard motor 100 was used as an example of a ship's propulsion system, but an inboard motor or a jet propulsion system could also be used.

[0066] In the above embodiment, the outboard motor 100 is equipped only with an engine body 122 as a drive source, but the ship's propulsion system may be a hybrid type equipped with a motor in addition to the engine.

[0067] In the above embodiment, the rotation axis As of the shoe 316 is parallel to the rotation axis Ap of the propeller shaft 136, but the rotation axis of the shoe does not necessarily have to be parallel to the rotation axis of the propeller shaft.

[0068] In the above embodiment, a friction material 319 is provided in the second portion 318, but it is not necessarily required that a friction material be provided.

[0069] In the above embodiment, the shape of the inner circumferential surface 302S of the cover 302 in an axial view of the propeller shaft 136 is circular, but the shape of the inner circumferential surface of the cover in an axial view of the propeller shaft is arbitrary. In the above embodiment, the shape of the outer circumferential surface 319S of the friction material 319 in an axial view of the propeller shaft 136 is arc-shaped, but the shape of the outer circumferential surface of the friction material in an axial view of the propeller shaft is arbitrary.

[0070] In the above embodiment, the entire outer surface 319S separates from the cover 302 simultaneously, but the contact surface of the friction material with the cover may gradually separate from the cover 302 as the rotational speed of the engine body 122 increases.

[0071] In the above embodiment, the shoe 316 includes a first metal and a second metal, but the shoe does not necessarily have to include a first metal and a second metal. In other words, the position of the center of gravity of the shoe may be adjusted, for example, by changing the shape of the shoe or by changing the density distribution of the shoe in the direction of rotation of the propeller shaft.

[0072] In the above embodiment, the outboard motor 100 is equipped with three shoes 316, but a ship's propulsion system only needs to be equipped with at least one shoe.

[0073] In the above embodiment, the outboard motor 100 is equipped with a torsion spring 320 as an elastic body, but the ship's propulsion system may be equipped with an elastic body other than a torsion spring.

[0074] In the above embodiment, oil is stored inside the housing 340, but oil does not need to be stored inside the case.

[0075] In the above embodiment, a propeller shaft 136 was exemplified as the shaft, but other types of shafts may also be used. [Explanation of Symbols]

[0076] 10: Ship 100: Outboard motor 110: Outboard motor body 111: Propeller 112: Cowl 113: Upper cowl 114: Lower cowl 116: Casing 117: Upper case 118: Lower case 120: Engine assembly 122: Engine body 123: Crankshaft 124: Journal 125: Spline 126: Intake system components 128: Electrical components 132: Drive shaft 136: Propeller shaft 140: Transmission mechanism 141: First gear 142: Second gear 143: Third gear 145: Dog clutch 150: Suspension system 152: Clamp bracket 153: Support 154: Tilt axis 156: Swivel bracket 200: Hull 202: Hull body 204: Living space 206: Space 210: Transom 220: Partition wall 240: Cockpit 250: Controls 252: Steering wheel 254: Shift / throttle lever 256: Monitor 258: Input device 300: Silencer 302: Cover 302S: Inner surface 310: Key 312: Base 314: Shoe pin 316: Shoe 317: First part 318: Second part 319: Friction material 319S: Outer surface 320: Torsion spring 324: Stopper 326: Shoe plate 328: Thrust washer 330: Clip 340: Housing Ac: Rotation axis Ap: Rotation axis As: Rotation axis At: Tilt axis CG: Center of gravity E1: First end E2: Second end RD1: First rotation direction RD2: Second rotation direction

Claims

1. A ship propulsion system, The engine and The propeller shaft and A transmission mechanism for transmitting the driving force of the engine to the propeller shaft, A drive gear that rotates by the driving force of the aforementioned engine, A transmission mechanism having a driven gear that meshes with the drive gear, A cover that covers the outer circumference of the propeller shaft, A shoe pin positioned between the propeller shaft and the cover, the shoe pin rotates around the propeller shaft in conjunction with the rotation of the propeller shaft, A shoe attached to the shoe pin and rotating around the shoe pin, A first portion located on one side in a direction intersecting the radial direction of the propeller shaft with respect to the shoe pin, It has a second portion located on the other side in a direction intersecting the radial direction of the propeller shaft with respect to the shoe pin, The center of gravity of the shoe is located at the first part, and the shoe is An elastic body that biases the second portion and the cover to come into contact with each other, A ship's propulsion system equipped with the following features.

2. A ship propulsion system according to claim 1, The second part is a marine propulsion system in which the shoe separates from the cover by receiving centrifugal force generated as the propeller shaft rotates.

3. A ship propulsion system according to claim 2, The second part is a marine propulsion system that separates from the cover when the engine's rotational speed is greater than the trolling rotational speed.

4. A ship propulsion system according to claim 1, A marine propulsion system in which the axis of rotation of the shoe is parallel to the axis of rotation of the propeller shaft.

5. A ship propulsion system according to claim 1, A ship propulsion system, wherein the second part is provided with friction material at the location where it contacts the cover.

6. A ship propulsion system according to claim 5, The shape of the inner circumferential surface of the cover in an axial view of the propeller shaft is circular. A marine propulsion system in which the shape of the outer surface of the friction material in an axial view of the propeller shaft is arc-shaped.

7. A ship propulsion system according to claim 6, The friction material has a contact surface with the cover, A marine propulsion system in which, as the shoe rotates around the shoe pin, the friction material separates from the cover, and the entire contact surface separates from the cover simultaneously.

8. A ship propulsion system according to claim 1, The shoe comprises a first metal and a second metal having a lower specific gravity than the first metal. A ship propulsion system in which the first metal is present in greater quantities in the first part than in the second part.

9. A ship propulsion system according to claim 8, The first metal is iron, The second metal is aluminum, in a ship's propulsion system.

10. A ship propulsion system according to claim 1, The aforementioned ship propulsion system is a ship propulsion system comprising a plurality of the aforementioned shoes.

11. A ship propulsion system according to claim 10, A ship propulsion system in which the plurality of shoes are arranged at equal intervals in the direction of rotation of the propeller shaft.

12. A ship propulsion system according to claim 1, The elastic body is a torsion spring in a ship's propulsion system.

13. A ship propulsion system according to claim 12, The torsion spring is wrapped around the shoe pin, The first end of the torsion spring is connected to the shoe, A marine propulsion system in which the second end of the torsion spring is connected to another part of the marine propulsion system that rotates together with the shoe pin around the propeller shaft.

14. A ship propulsion system according to claim 13, The first end of the torsion spring is connected to the first portion of a ship's propulsion system.

15. A ship propulsion system according to claim 1, further, It is equipped with a drive shaft that rotates by the driving force of the aforementioned engine, The drive gear rotates together with the drive shaft, A marine propulsion system further comprising a dog clutch that is movable between a connection position where it connects to the driven gear and a disconnection position where it is separated from the driven gear, and which rotates together with the propeller shaft.

16. A ship propulsion system according to claim 1, further, A ship's propulsion system comprising a shoe plate connected to the aforementioned shoe pin.

17. A ship propulsion system according to claim 1, further, A ship propulsion system comprising a stopper positioned between the first part and the cover.

18. A ship propulsion system according to claim 1, further, The case comprises the cover, the shoe pin, the shoe, and the elastic body, Inside the aforementioned case is a ship's propulsion system, in which oil is stored.

19. The hull and, A ship propulsion system according to claim 1, attached to the rear of the hull, A ship equipped with these features.

20. A ship propulsion system, The engine and The shaft and A transmission mechanism for transmitting the driving force of the engine to the shaft, A drive gear that rotates by the driving force of the aforementioned engine, A transmission mechanism having a driven gear that meshes with the drive gear, A cover that covers the outer circumference of the shaft, A shoe pin disposed between the shaft and the cover, the shoe pin which rotates around the shaft as the shaft rotates, A shoe attached to the shoe pin and rotating around the shoe pin, A first portion located on one side in a direction intersecting the radial direction of the shaft with respect to the shoe pin, It has a second portion located on the other side in a direction intersecting the radial direction of the shaft with respect to the shoe pin, The center of gravity of the shoe is located at the first part, and the shoe is An elastic body that biases the second portion and the cover to come into contact with each other, A ship's propulsion system equipped with the following features.

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