Propeller Unit

Abstract

To reduce economic load of maintenance by suppressing early deterioration, damage, or function deterioration in a part having shock absorption function such as a damper.SOLUTION: A propeller unit 21 includes: a propeller 22; a cylindrical member 31 inserted into an insertion hole 24 of a hub 23 of the propeller 22 and coupled to be incapable of rotation to a propeller shaft 9; and a plurality of spherical elastic bodies 41, 42 provided in between the cylindrical member 31 and a hub 23 for absorbing impact between the propeller shaft 9 and the propeller 22 as well as transmitting rotation of the propeller shaft 9 to the propeller 22, a plurality of coronary shape concave units 34 are formed on the outer periphery surface of the cylindrical member 31, a plurality of rounded bottom grooves 27 are formed on the inner periphery surface of the insertion hole 24, and respective spherical elastic bodies 41, 42 are retained to be capable of revolution between coronary shape concave units 34 and the rounded bottom grooves 27 facing each other.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a propeller unit for a marine propulsion device. [Background technology]

[0002] In general, a propeller unit is provided at the rear end of a propeller shaft of a marine propulsion device. The propeller unit includes a propeller having a plurality of blades provided on the outer periphery of a hub, and a cylindrical bushing. The bushing is inserted into a hole provided in the center of the hub and is fixed to the hub so as not to rotate. The rear end of the propeller shaft is inserted inside the bushing. The bushing is spline-coupled to the rear end of the propeller shaft and is fixed to the propeller shaft so as not to rotate. The propeller is connected to the rear end of the propeller shaft via the bushing in this manner, and rotation of the propeller shaft is transmitted to the propeller via the bushing.

[0003] Among conventional propeller units, there is one equipped with a damper that absorbs shock between the propeller shaft and the propeller. The following Patent Document 1 describes a conventional propeller unit equipped with such a damper. In this propeller unit, a bushing is fitted into a hub so as to be movable in a circumferential direction relative to the hub. Also, on the inner peripheral surface of the hub, three ribs are provided at intervals in the circumferential direction of the hub, protruding radially inward of the hub and extending in the axial direction of the hub. Also, on the outer peripheral surface of the bushing, three ribs are provided at intervals in the circumferential direction of the bushing, protruding radially outward of the bushing and extending in the axial direction of the bushing. Also, a damper made of an elastic material such as natural rubber is disposed in a space surrounded by the inner peripheral surface of the hub, the outer peripheral surface of the bushing, the rib provided on the inner peripheral surface of the hub, and the rib provided on the outer peripheral surface of the bushing. When the propeller shaft rotates, causing the bushing to rotate accordingly, the damper is pressed circumferentially by the ribs on the inner circumferential surface of the hub and the ribs on the outer circumferential surface of the bushing, causing the damper to deform, thereby absorbing the impact between the propeller shaft and the propeller. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2014-141120 A Summary of the Invention [Problem to be solved by the invention]

[0005] In the propeller unit described in the above-mentioned Patent Document 1, the damper has an overall band-like shape with a non-connected portion, as shown in Figure 12 of the same document. Moreover, the damper is disposed between the bushing and the hub with the non-connected portion fitted into a rib provided on the outer circumferential surface of the bushing, as shown in Figures 13 and 17 of the same document. Due to this configuration, the damper cannot change its orientation between the bushing and the hub.

[0006] If the damper cannot change its orientation between the bushing and the hub, stress will repeatedly concentrate on the same location in the damper, which may cause early deterioration or damage to the damper. In other words, if the damper cannot change its orientation between the bushing and the hub, when the damper is pressed against the rib of the bushing and the rib of the hub, the location in the damper that is most deformed will always be approximately the same. As a result, during use of the marine propulsion device, stress will repeatedly concentrate on the same location in the damper, which may cause early deterioration or damage to the location.

[0007] Moreover, the damper described in the above Patent Document 1 has a complex shape in which multiple cylindrical elastic members are connected, as described in paragraph 0058 of the same document, and furthermore, as shown in FIG. 12 of the same document, a large number of projections and recesses are formed on the surface of the damper.

[0008] If the damper has a complex shape or has many projections and recesses on its surface, salt, sand, dirt, etc. are likely to accumulate in the recesses of the damper, between the damper and the hub, or between the damper and the bushing. If salt, sand, dirt, etc. accumulates in this way, the accumulated salt, sand, dirt, etc. may hinder the damper from deforming, and the shock absorbing function of the damper may be reduced.

[0009] Furthermore, when the damper has a complex shape, such as the propeller unit described in Patent Document 1, the cost of manufacturing the damper may be high, which may increase the price of the damper. As a result, the economic burden on the user may be large when replacing a deteriorated or damaged damper with a new damper, or when replacing a propeller unit whose shock absorbing function has deteriorated with a new propeller unit.

[0010] The present invention has been made in consideration of problems such as those described above, and an object of the present invention is to provide a propeller unit that can suppress early deterioration, damage, or functional decline of parts having a shock absorbing function, such as dampers, and can reduce the economic burden of maintenance. [Means for solving the problem]

[0011] In order to solve the above problems, the present invention The first propeller unit a propeller unit for a marine propulsion device, the propeller unit comprising: a hub having an insertion hole formed in its center; a propeller having a plurality of blades provided on the hub; a cylindrical member that is inserted into the insertion hole, a propeller shaft is inserted inside the cylindrical member and non-rotatably coupled to the propeller shaft; and a plurality of elastic bodies that are provided between the cylindrical member and the hub and absorb shock between the propeller shaft and the propeller and transmit rotation of the propeller shaft to the propeller, the cylindrical member being inserted into the insertion hole with play such that the cylindrical member is movable in a circumferential direction relative to the hub, a plurality of first recesses are formed on an outer circumferential surface of the cylindrical member so as to be aligned in the circumferential direction, and a plurality of second recesses are formed on an inner circumferential surface of the insertion hole so as to be aligned in the circumferential direction and opposite the plurality of first recesses, and each of the elastic bodies Spherical a first portion of the elastic body is located in the first recess, a second portion of the elastic body is located in the second recess, and the elastic body is rotatably held between the first recess and the second recess which face each other. In the plurality of first recesses and the plurality of second recesses, one of the first recesses and the second recesses facing each other is formed in a spherical crown shape that is a part of a sphere having a diameter larger than a diameter of the elastic body placed in the one recess, and the other recess is a groove that extends in a direction parallel to the axis of the propeller shaft and has a cross-sectional shape formed in an arc shape that is a part of a circle having a diameter larger than a diameter of the elastic body placed in the other recess. It is characterized by: In order to solve the above problems, a second propeller unit of the present invention is a propeller unit for a marine propulsion device, comprising: a hub having an insertion hole formed in its center; a propeller having a plurality of blades provided on the hub; a cylindrical member that is inserted into the insertion hole, has a propeller shaft inserted therein, and is non-rotatably coupled to the propeller shaft; and a plurality of elastic bodies that are provided between the cylindrical member and the hub and absorb impact between the propeller shaft and the propeller and transmit rotation of the propeller shaft to the propeller, the cylindrical member being inserted into the insertion hole with play such that the cylindrical member is movable circumferentially relative to the hub, a plurality of first recesses are formed on the outer peripheral surface of the material so as to be aligned in the circumferential direction, and a plurality of second recesses are formed on the inner peripheral surface of the insertion hole so as to be aligned in the circumferential direction opposite the plurality of first recesses; each of the elastic bodies is formed in a spherical or cylindrical shape, a first portion of the elastic body is located within the first recess and a second portion of the elastic body is located within the second recess and is rotatably held between the first recess and the second recess which are opposed to each other; a convex portion protruding radially outward is provided on the outer peripheral surface of the tubular member, and a third recess is provided on the inner peripheral surface of the insertion hole so as to correspond to the convex portion, and a tip portion of the convex portion is located within the third recess. In order to solve the above problems, a third propeller unit of the present invention is a propeller unit for a marine propulsion device, comprising: a hub with an insertion hole formed in its center; a propeller having a plurality of blades provided on the hub; a cylindrical member that is inserted into the insertion hole, a propeller shaft is inserted inside the cylindrical member and is non-rotatably coupled to the propeller shaft; and a plurality of elastic bodies that are provided between the cylindrical member and the hub and absorb shocks between the propeller shaft and the propeller and transmit the rotation of the propeller shaft to the propeller. The cylindrical member is inserted into the insertion hole with play so as to be movable in a circumferential direction relative to the hub, and a circumferential groove is formed on the outer circumferential surface of the cylindrical member. a plurality of first recesses are formed in the inner peripheral surface of the insertion hole so as to be aligned in the circumferential direction, a plurality of second recesses are formed in the inner peripheral surface of the insertion hole so as to be aligned in the circumferential direction opposite the plurality of first recesses, each of the elastic bodies is formed in a spherical or cylindrical shape, a first portion of the elastic body is located in the first recess and a second portion of the elastic body is located in the second recess and is rotatably held between the first recess and the second recess which face each other, a buffer member formed in a ring shape from an elastic material is provided between the tubular member and the hub, the plurality of elastic bodies are arranged on the outer periphery side of one axial side portion of the tubular member, and the buffer member is arranged on the outer periphery side of the other axial side portion of the tubular member. Effect of the Invention

[0012] According to the present invention, early deterioration, damage, or deterioration in function of parts having a shock absorbing function, such as dampers, can be suppressed, and the economic burden of maintenance can be reduced. [Brief description of the drawings]

[0013] [Figure 1] 1 is an explanatory diagram showing an outboard motor provided with a propeller unit according to a first embodiment of the present invention. FIG. [Diagram 2] 1 is a cross-sectional view showing a propeller unit according to a first embodiment of the present invention. [Diagram 3] 1 is an external view showing a propeller unit according to a first embodiment of the present invention as viewed from the front. FIG. [Figure 4] 4 is a cross-sectional view showing a cross section of the propeller unit taken along the cutting line IV-IV in FIG. 2, as viewed from the front. [Diagram 5] 1 is an external view showing a cylindrical member and the like in a propeller unit according to a first embodiment of the present invention, as viewed from the upper left rear side. FIG. [Figure 6] FIG. 4 is an explanatory diagram showing the sizes of a spherical crown recess and a round bottom groove in a propeller unit according to a first embodiment of the present invention. [Figure 7] FIG. 4 is a cross-sectional view showing a propeller unit according to a second embodiment of the present invention. [Figure 8] 8 is a cross-sectional view showing a cross section of the propeller unit taken along line VIII-VIII in FIG. 7, as viewed from the front. [Figure 9] 13 is an external view showing a tubular member in a propeller unit according to a second embodiment of the present invention, as viewed from the upper left rear side. FIG. [Figure 10] FIG. 11 is an external view showing a cylindrical member and the like in a propeller unit according to another embodiment of the present invention, as viewed from the upper left rear side. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] A propeller unit according to an embodiment of the present invention is a propeller unit for a marine propulsion device, and includes a propeller, a tubular member, and multiple elastic bodies. The propeller has a hub with an insertion hole formed in the center, and multiple blades provided on the hub. The tubular member is inserted into the insertion hole of the hub. A propeller shaft is inserted into the inside of the tubular member, and the tubular member is non-rotatably coupled to the propeller shaft. Multiple elastic bodies are provided between the tubular member and the hub. These elastic bodies have the function of absorbing impact between the propeller shaft and the propeller, and transmitting rotation of the propeller shaft to the propeller.

[0015] The cylindrical member is inserted into the insertion hole of the hub with some play so that the cylindrical member can move in the circumferential direction relative to the hub. A plurality of first recesses are formed on the outer peripheral surface of the cylindrical member so as to be aligned in the circumferential direction. A plurality of second recesses are formed on the inner peripheral surface of the insertion hole of the hub so as to be aligned in the circumferential direction and face the plurality of first recesses, respectively. Each elastic body is formed in a spherical or cylindrical shape. Each elastic body is held rotatably between the first recess and the second recess, which face each other, with the first portion of the elastic body located in the first recess and the second portion of the elastic body located in the second recess.

[0016] In the propeller unit of this embodiment having such a configuration, each elastic body is formed in a spherical or cylindrical shape and is held rotatably between the first recess and the second recess, so that each elastic body can change direction when it is subjected to a water flow around the propeller unit 21 or when the torque between the cylindrical member 33 and the hub 23 changes suddenly. By changing the direction of each elastic body, the location where stress occurs in each elastic body changes. Therefore, according to the propeller unit of this embodiment, it is possible to suppress early deterioration or damage of each elastic body caused by repeated stress concentration at the same location of each elastic body.

[0017] Moreover, each elastic body has a simple shape because it is spherical or cylindrical. Therefore, salt, sand, dirt, etc. are unlikely to adhere to each elastic body. Moreover, each elastic body can rotate between the first recess and the second recess facing each other. This allows the water around the propeller unit to flow easily and smoothly around each elastic body. Therefore, salt, sand, dirt, etc. around each elastic body can be discharged to the outside of the propeller unit by the water flow, and accumulation of salt, sand, dirt, etc. around each elastic body, for example, in the first recess or the second recess, can be suppressed. Therefore, according to the propeller unit of this embodiment, it is possible to suppress the elastic deformation of each elastic body being hindered by salt, sand, dirt, etc. adhering to each elastic body or accumulating around each elastic body, and the deterioration of the impact absorbing function of each elastic body.

[0018] In addition, since each elastic body has a simple shape, it is easy to manufacture and inexpensive. Therefore, the economic burden of replacing the elastic bodies is small. Therefore, according to the propeller unit of this embodiment, it is possible to reduce the economic burden of maintenance. EXAMPLES

[0019] Several embodiments of the present invention will be described below. In each embodiment, the directions of front (Fd), back (Bd), top (Ud), bottom (Dd), left (Ld), and right (Rd) follow the arrows at the bottom right of the drawings such as Figures 1, 2, and 5.

[0020] (Outboard motor) FIG. 1 shows an outboard motor 1 as a marine propulsion device provided with a propeller unit 21 according to a first embodiment of the present invention. In the outboard motor 1 shown in FIG. 1, a bottom cowling 2 and a top cowling 3 are provided at the upper part, and a power source 4 is provided inside them. An engine (internal combustion engine) or an electric motor is used as the power source 4. An upper casing 5 is provided below the bottom cowling 2, and a drive shaft 6 extending downward from the power source 4 is provided inside the upper casing 5. A lower casing 7 is provided at the lower part of the outboard motor 1, and a gear mechanism 8 including a plurality of bevel gears and the like, and a propeller shaft 9 extending in a direction perpendicular to the drive shaft 6 are provided inside the upper casing 5. A propeller unit 21 is provided at the rear end of the propeller shaft 9. The outboard motor 1 is also provided with a clamp bracket 11 for mounting the outboard motor 1 to a marine vessel, and a swivel bracket 10 for enabling the outboard motor 1 to tilt up and down.

[0021] When the power source 4 is operated, the power of the power source 4 is transmitted to the propeller shaft 9 via the drive shaft 6 and the gear mechanism 8, and the propeller unit 21 rotates together with the propeller shaft 9. When the boat to which the outboard motor 1 is attached is driven forward, the propeller shaft 9 and the propeller unit 21 rotate, for example, counterclockwise as viewed from the front of the outboard motor 1. When the boat is driven backward, the propeller shaft 9 and the propeller unit 21 rotate, for example, clockwise as viewed from the front of the outboard motor 1. The rotation direction of the propeller shaft 9 and the propeller unit 21 can be switched by switching a clutch provided in the gear mechanism 8 when the power source 4 is an engine, or by switching the rotation direction of the electric motor when the power source 4 is an electric motor.

[0022] (Propeller unit configuration) FIG. 2 shows a propeller unit 21 according to a first embodiment of the present invention, and more specifically, shows a cross section of the propeller unit 21 cut along a plane extending in the front-rear and up-down directions including the axis of the propeller shaft 9, as viewed from the left. FIG. 3 shows the propeller unit 21 as viewed from the front. FIG. 4 shows a cross section of the propeller unit 21 cut along the cutting line IV-IV in FIG. 2, as viewed from the front. Note that the blades 28 are not shown in FIG. 4. FIG. 5 shows a cylindrical member 31 according to the first embodiment of the present invention as viewed from the upper left rear side, and more specifically, FIG. 5(A) shows the cylindrical member 31 without the spherical elastic bodies 41, 42 and the annular elastic body 43, and FIG. 5(B) shows the cylindrical member 31 with the spherical elastic bodies 41, 42 and the annular elastic body 43 provided thereon.

[0023] As shown in FIG. 2, the propeller unit 21 includes a propeller 22, a cylindrical member 31, a plurality of spherical elastic bodies 41, 42, and a plurality of annular elastic bodies 43.

[0024] The propeller 22 includes a hub 23 and a plurality of blades 28. The hub 23 is formed in a cylindrical shape. An insertion hole 24 and a large diameter hole 25 are formed in the center of the hub 23. The insertion hole 24 is a hole into which the rear end of the propeller shaft 9 and the cylindrical member 31 are inserted, and is formed in a portion of the hub from the approximate axial center to the rear end. The large diameter hole 25 is a hole into which the portion forward of the rear end of the propeller shaft 9 and the front spacer 12, etc. are inserted, and is formed in the front end portion of the hub. The large diameter hole 25 is disposed coaxially with the insertion hole 24 and communicates with the insertion hole 24. The diameter of the large diameter hole 25 is larger than the diameter of the insertion hole 24, and an annular step 26 is formed between the large diameter hole 25 and the insertion hole 24. The blades 28 are provided on the outer periphery of the hub 23.

[0025] The tubular member 31 is formed into a cylindrical shape from a metal material such as stainless steel or brass. The tubular member 31 is inserted into the insertion hole 24 of the hub 23 with some play so that the tubular member 31 can move circumferentially relative to the hub 23. In other words, the outer diameter of each part of the tubular member 31 is set to a value smaller than the diameter of each part of the insertion hole 24 that faces each part of the tubular member 31 so that the tubular member 31 can move circumferentially relative to the hub 23 within the insertion hole 24 of the hub 23.

[0026] Furthermore, a shaft insertion hole 32 into which the rear end of the propeller shaft 9 is inserted is formed on the inner peripheral side of the cylindrical member 31. Splines 33 are formed on the inner peripheral surface of the shaft insertion hole 32, and splines are also formed on the outer peripheral surface of the rear end of the propeller shaft 9. The cylindrical member 31 is non-rotatably coupled to the rear end of the propeller shaft 9 by fitting the splines 33 of the shaft insertion hole 32 into the splines of the propeller shaft 9. Furthermore, the propeller 22 and the cylindrical member 31 are attached to the rear end of the propeller shaft 9 using a front spacer 12, a rear spacer 13, and a nut 14.

[0027] The plurality of spherical elastic bodies 41, 42 have the function of absorbing shocks between the propeller shaft 9 and the propeller 22, and transmitting the rotation of the propeller shaft 9 to the propeller 22. Each of the spherical elastic bodies 41, 42 is formed in a spherical shape. Each of the spherical elastic bodies 41, 42 is provided between the cylindrical member 31 and the hub 23. As shown in FIG. 2, each of the spherical elastic bodies 41, 42 is disposed on the outer periphery of the front portion of the cylindrical member 31. As shown in FIG. 3 or FIG. 4, in this embodiment, six spherical elastic bodies 41, 42 are disposed at equal intervals (60° intervals) around the entire circumference of the cylindrical member 31.

[0028] The plurality of spherical elastic bodies 41, 42 include two types of spherical elastic bodies having different hardness, that is, low-hardness spherical elastic bodies 41 and high-hardness spherical elastic bodies 42. Specifically, the low-hardness spherical elastic bodies 41 are set to a first predetermined hardness, and the high-hardness spherical elastic bodies 42 are set to a second predetermined hardness higher than the first hardness. The low-hardness spherical elastic bodies 41 are formed of, for example, low-resilience rubber. The high-hardness spherical elastic bodies 42 are formed of, for example, high-resilience rubber or plastic. The diameter D1 of the low-hardness spherical elastic bodies 41 is larger than the diameter D2 of the high-hardness spherical elastic bodies 42 (see FIG. 6). In this embodiment, the six spherical elastic bodies 41, 42 include three low-hardness spherical elastic bodies 41 and three high-hardness spherical elastic bodies 42. 4, in this embodiment, the low hardness spherical elastic bodies 41 and the high hardness spherical elastic bodies 42 are arranged alternately one by one in the circumferential direction of the cylindrical member 31. The spherical elastic bodies 41 and 42 are specific examples of "elastic bodies", the low hardness spherical elastic body 41 is a specific example of a "first elastic body", and the high hardness spherical elastic body 42 is a specific example of a "second elastic body".

[0029] Each of the spherical elastic bodies 41, 42 is disposed between the spherical crown recess 34 formed in the cylindrical member 31 and the round bottom groove 27 formed in the hub 23. That is, as shown in FIG. 5(A), the outer peripheral surface of the front portion of the cylindrical member 31 is formed with the same number of spherical crown recesses 34 as the number of the spherical elastic bodies 41, 42 arranged in the circumferential direction. In this embodiment, six spherical crown recesses 34 are formed, and these spherical crown recesses 34 are arranged at equal intervals (60 degree intervals) around the entire circumference of the cylindrical member 31. On the other hand, as shown in FIG. 2 to FIG. 4, the inner peripheral surface of the front portion of the insertion hole 24 is formed with the same number of round bottom grooves 27 as the number of the spherical elastic bodies 41, 42 arranged in the circumferential direction. In this embodiment, six round bottom grooves 27 are formed, and these round bottom grooves 27 are arranged at equal intervals (60 degree intervals) around the entire circumference of the insertion hole 24. 4, each spherical crown recess 34 opens radially outward of the cylindrical member 31, and each round bottom groove 27 opens radially inward of the hub 23, with the six spherical crown recesses 34 and the six round bottom grooves 27 facing each other. In each of the spherical elastic bodies 41, 42, a portion (first portion) facing radially inward of the cylindrical member 31 is located within the spherical crown recess 34, and a portion (second portion) facing radially outward of the cylindrical member 31 is located within the round bottom groove 27. The spherical crown recess 34 is a specific example of a "first recess," and the round bottom groove 27 is a specific example of a "second recess."

[0030] 6(A) shows an enlarged view of a part of the cross section of the hub 23 shown in FIG. 4, and FIG. 6(B) shows an enlarged view of a part of the cross section of the cylindrical member 31 shown in FIG. 4. As shown in FIG. 6(B), in the cylindrical member 31, each spherical crown-shaped recess 34 is formed in a spherical crown shape that is a part of a sphere S having a diameter D3 larger than both the diameter D1 of the low hardness spherical elastic body 41 and the diameter D2 of the high hardness spherical elastic body 41. Also, as shown in FIG. 6(A), in the hub 23, each round-bottom groove portion 27 is formed so that the cross-sectional shape thereof is an arc shape that is a part of a circle C having a diameter D4 larger than both the diameter D1 of the low hardness spherical elastic body 41 and the diameter D2 of the high hardness spherical elastic body 41. Also, in this embodiment, the diameter D3 of the sphere S corresponding to the spherical crown shape of each spherical crown-shaped recess 34 and the diameter D4 of the circle C corresponding to the arc shape of the cross-sectional shape of each round-bottom groove portion 27 are equal to each other.

[0031] By setting the diameters D1, D2 of the spherical elastic bodies 41, 42, the diameter D3 of the sphere S corresponding to the spherical crown shape of each spherical crown-shaped recess 34, and the diameter D4 of the circle C corresponding to the arc shape of the cross section of each round bottom groove 27 in this manner, the spherical elastic bodies 41, 42 are held with some play between the opposing spherical crown-shaped recess 34 and round bottom groove 27. Therefore, as will be described later, the spherical elastic bodies 41, 42 can rotate on their own axis (rotate around the center of the spherical elastic body) between the opposing spherical crown-shaped recess 34 and round bottom groove 27.

[0032] In the hub 23, each round bottom groove 27 extends in a direction parallel to the axis of the propeller shaft 9, as shown in Fig. 2. The front end of each round bottom groove 27 reaches the front end of the insertion hole 24, i.e., the step 26 between the large diameter hole 25 and the insertion hole 24. As a result, as shown in Fig. 3, the front end of each round bottom groove 27 communicates with the inside of the large diameter hole 25 and opens toward the front of the hub 23. In addition, the rear end of each round bottom groove 27 has the shape of a quarter sphere (a sphere divided into four equal parts by two planes including the center).

[0033] The multiple annular elastic bodies 43 have a function of absorbing shock between the propeller shaft 9 and the propeller 22. Each annular elastic body 43 is formed in an annular shape having a circular or elliptical cross section, for example, from an elastic material such as rubber. Each annular elastic body 43 is, for example, an O-ring. Each annular elastic body 43 is provided between the cylindrical member 31 and the hub 23. Also, as shown in FIG. 2, each annular elastic body 43 is disposed on the outer periphery side of a portion of the cylindrical member 31 extending from the approximate center to the rear in the axial direction. In this embodiment, three annular elastic bodies 43 are arranged in the cylindrical member 31 at a predetermined interval in the axial direction. The annular elastic body 43 is a specific example of a "buffer member."

[0034] As shown in FIG. 5(A), the cylindrical member 31 has annular grooves 35 formed on the outer periphery of a portion extending from the approximate center to the rear in the axial direction, the number of which is equal to the number of the annular elastic bodies 43. As shown in FIG. 5(B), each annular elastic body 43 is fitted in the annular groove 35. As shown in FIG. 2, the inner periphery of each annular elastic body 43 is located in the annular groove 35, and the inner periphery of each annular elastic body 43 contacts the bottom of the annular groove 35. Also, the outer periphery of each annular elastic body 43 protrudes from the annular groove 35 and rises outward in the radial direction of the cylindrical member 31, and the outer periphery of each annular elastic body 43 contacts the inner periphery of the insertion hole 24. Also, each annular elastic body 43 is provided between the bottom of the annular groove 35 and the inner periphery of the insertion hole 24 in a state in which it is elastically deformed by being pressed against the bottom of the annular groove 35 and the inner periphery of the insertion hole 24.

[0035] (Propeller unit function) The propeller unit 21 has a function of propelling the ship by the rotation of the propeller 22, as well as a shock absorbing function by the spherical elastic bodies, a gear mechanism protecting function by the spherical elastic bodies, a deterioration and damage suppressing function of the spherical elastic bodies, a shock absorbing function by the ring-shaped elastic bodies, and a backup power transmission function by the ring-shaped elastic bodies. These functions are explained below.

[0036] [Shock absorption function using spherical elastic bodies] First, the shock absorbing function of the spherical elastic bodies will be described. In Fig. 4, when the ship starts moving forward, the power of the power source 4 is transmitted to the propeller shaft 9 via the drive shaft 6 and the gear mechanism 8, and the propeller shaft 9 and the cylindrical member 31 start rotating in the counterclockwise direction (the direction of the arrow F in Fig. 4), first, the portion of the low hardness spherical elastic body 41 at position P1 is pressed against the spherical crown-shaped recess 34, and then the portion of the low hardness spherical elastic body 41 at position P2 presses the round bottom groove portion 27. At this time, each low hardness spherical elastic body 41 is sandwiched between the spherical crown-shaped recess 34 and the round bottom groove portion 27 and pressed, and compressed. As a result, the shock between the propeller shaft 9 (cylindrical member 31) and the propeller 22 is absorbed by each low hardness spherical elastic body 41. When each of the low hardness spherical elastic bodies 41 is compressed to a certain extent in this manner, the portion of each of the high hardness spherical elastic bodies 42 at position P3 is pressed against the spherical crown-shaped recess 34, and then the portion of each of the high hardness spherical elastic bodies 42 at position P4 presses against the round bottom groove 27. At this time, each of the high hardness spherical elastic bodies 42 is sandwiched between the spherical crown-shaped recess 34 and the round bottom groove 27 and pressed, and compressed. However, since each of the spherical elastic bodies 42 has a higher hardness than each of the spherical elastic bodies 41, the degree of compression of each of the spherical elastic bodies 42 is often smaller than the degree of compression of each of the spherical elastic bodies 41. However, the compression of each of the spherical elastic bodies 42 also absorbs the impact between the propeller shaft 9 and the propeller 22. Thereafter, while the propeller shaft 9 and the cylindrical member 31 are rotating counterclockwise, the rotation of the propeller shaft 9 and the cylindrical member 31 is transmitted to the propeller 22 by the spherical elastic bodies 41, .

[0037] 4, when the propeller shaft 9 and the cylindrical member 31 start to rotate in the clockwise direction (the direction of the arrow R in FIG. 4) when the ship starts to move backward, first, the portion of each low hardness spherical elastic body 41 at position Q1 is pressed against the spherical crown-shaped recess 34, and then, the portion of each low hardness spherical elastic body 41 at position Q2 presses against the round bottom groove portion 27. At this time, each low hardness spherical elastic body 41 is sandwiched between the spherical crown-shaped recess 34 and the round bottom groove portion 27 and compressed, so that the impact between the propeller shaft 9 and the propeller 22 is absorbed by each low hardness spherical elastic body 41. Next, the portion of each high hardness spherical elastic body 42 at position Q3 is pressed against the spherical crown-shaped recess 34, and then, the portion of each high hardness spherical elastic body 42 at position Q4 presses against the round bottom groove portion 27. At this time, each of the high-hardness spherical elastic bodies 42 is sandwiched and compressed between the spherical crown-shaped recess 34 and the round-bottom groove portion 27, whereby the impact between the propeller shaft 9 and the propeller 22 is absorbed by each of the high-hardness spherical elastic bodies 42. Thereafter, while the propeller shaft 9 and the cylindrical member 31 are rotating clockwise, the rotation of the propeller shaft 9 and the cylindrical member 31 is transmitted to the propeller 22 by each of the spherical elastic bodies 41, 42.

[0038] In this way, when the torque of the rotation of the propeller shaft 9 fluctuates when the vessel starts to move forward or backward, when the vessel reverses its direction of travel, or when it rapidly accelerates or decelerates, the impact between the propeller shaft 9 (cylindrical member 31) and the propeller 22 is absorbed in two stages by each of the spherical elastic bodies 41, 42. This makes it possible to effectively mitigate the impact between the propeller shaft 9 and the propeller 22 caused by torque fluctuations or the like.

[0039] [Gear mechanism protection function using spherical elastic bodies] Next, the gear mechanism protection function of the spherical elastic bodies will be described. The hardness of each of the spherical elastic bodies 41, 42 (particularly the hardness of the high-hardness spherical elastic body 42) is set so that the rotation of the propeller shaft 9 and the cylindrical member 31 can be reliably transmitted to the propeller 22 when the magnitude of the load applied to the propeller 22 is within a normal range. Furthermore, the hardness of each of the spherical elastic bodies 41, 42 is set so that when the load applied to the propeller 22 becomes excessive and the magnitude of the load significantly exceeds the above-mentioned normal range, the spherical elastic bodies 41, 42 are intentionally broken by the excessive load, and the transmission of the excessive load from the propeller 22 to the propeller shaft 9 is cut off. When the propeller shaft 9 and the cylindrical member 31 are rotating due to the power of the power source 4, if the propeller 22 comes into contact with a reef, the bottom of the water, or the like and an excessive load is applied to the propeller 22, the spherical elastic bodies 41, 42 will break and the excessive load will not be transmitted to the propeller shaft 9. This makes it possible to prevent the excessive load from being transmitted to the gear mechanism 8 etc. via the propeller shaft 9 and causing damage to the gear mechanism 8 etc.

[0040] [Spherical elastic body deterioration and damage prevention function] Next, the deterioration and damage suppression function of the spherical elastic bodies will be described. As described above, each of the spherical elastic bodies 41, 42 is held with a play between the spherical crown recess 34 and the round bottom groove 27 facing each other. Therefore, each of the spherical elastic bodies 41, 42 can rotate on its axis between the spherical crown recess 34 and the round bottom groove 27 facing each other. For example, when the propeller shaft 9 and the cylindrical member 31 are stopped, the spherical elastic bodies 41, 42 may rotate on their axis due to the water flow around the propeller unit 21. In addition, when the number of revolutions of the propeller shaft 9 or the load applied to the propeller 22 suddenly changes and the torque between the cylindrical member 33 and the hub 23 suddenly changes, the spherical elastic bodies 41, 42 may be pushed by either the spherical crown recess 34 or the round bottom groove 27 and rotate on their axis. The spherical elastic bodies 41, 42 rotate on their axis, changing their orientation. When the orientation of the spherical elastic bodies 41, 42 changes, the portion of the spherical elastic bodies 41, 42 that is pressed against the spherical crown recess 34 and the portion of the spherical elastic bodies 41, 42 that presses against the round bottom groove portion 27 change when the propeller shaft 9 and the cylindrical member 31 rotate. That is, when the orientation of the spherical elastic bodies 41, 42 changes, the portion in which stress occurs in the spherical elastic bodies 41, 42 changes when the propeller shaft 9 and the cylindrical member 31 rotate. This prevents repeated stress concentration at the same location in the spherical elastic bodies 41, 42. This prevents the spherical elastic bodies 41, 42 from prematurely deteriorating or breaking due to repeated stress concentration at the same location.

[0041] [Shock absorption function using ring-shaped elastic body] Next, the shock absorbing function of the annular elastic body will be described. An annular elastic body 43 is provided on the outer circumferential side of the cylindrical member 31 from the approximate center to the rear in the axial direction. In FIG. 1, for example, when the front part of the tip of the blade 28 of the propeller 22 hits the bottom of the water while the ship is moving forward, and an impact is applied to the propeller 22 in a direction intersecting the axis of the propeller shaft 9 as shown by the arrow A in the figure, the annular elastic body 43 is elastically deformed by receiving the impact. Due to the elastic deformation of the annular elastic body 43, the propeller 22 can be displaced to a certain extent relative to the propeller shaft 9 in a direction in which the axis of the propeller 22 is inclined or displaced relative to the axis of the propeller shaft 9. This makes it possible to mitigate the impact applied to the propeller 22 in a direction intersecting the axis of the propeller shaft 9.

[0042] [Back-up power transmission function using an elastic ring] Next, the preliminary power transmission function of the annular elastic body will be described. Each annular elastic body 43 is provided between the bottom surface of the annular groove 35 and the inner peripheral surface of the insertion hole 24 in a state where it is pressed against the bottom surface of the annular groove 35 and the inner peripheral surface of the insertion hole 24 and elastically deformed. Therefore, when the propeller shaft 9 and the cylindrical member 31 rotate, the propeller 22 rotates due to friction between each annular elastic body 43 and the inner peripheral surface of the insertion hole 24. In this way, each annular elastic body 43 has the ability to transmit the rotation of the propeller shaft 9 and the cylindrical member 31 to the propeller 22. As described above, if an excessive load is applied to the propeller 22 and each of the spherical elastic bodies 41, 42 is damaged, it becomes difficult to transmit the rotation of the propeller shaft 9 and the cylindrical member 31 to the propeller 22 via the spherical elastic bodies 41, 42. Even when such an event occurs, if the rotation speed of the propeller shaft 9 and the tubular member 31 is low and the magnitude of the load applied between the tubular member 31 and the propeller 22 is smaller than the frictional force between each annular elastic body 43 and the inner circumferential surface of the insertion hole 24, the rotation of the propeller shaft 9 and the tubular member 31 can be transmitted to the propeller 22 via each annular elastic body 43. Therefore, even if each of the spherical elastic bodies 41, 42 is damaged, the ship can be moved thereafter, albeit at a low speed, and can be docked.

[0043] As described above, the propeller unit 21 of the first embodiment of the present invention includes the spherical elastic bodies 41, 42 as members having the functions of absorbing shock between the propeller shaft 9 and the propeller 22 and transmitting the rotation of the propeller shaft 9 to the propeller 22. Each of the spherical elastic bodies 41, 42 is held with some play between the spherical crown-shaped recess 34 and the round bottom groove 27, and each of the spherical elastic bodies 41, 42 can rotate on its own axis between the spherical crown-shaped recess 34 and the round bottom groove 27. With this configuration, each of the spherical elastic bodies 41, 42 can change direction when subjected to a water flow around the propeller unit 21 or when the torque between the cylindrical member 33 and the hub 23 suddenly changes, as described above. Since the orientation of each spherical elastomer 41, 42 can be changed in this manner, repeated stress concentration at the same location in the spherical elastomers 41, 42 can be prevented, and premature deterioration or damage to the spherical elastomers 41, 42 due to this repeated stress concentration can be prevented.

[0044] In the propeller unit 21 of the first embodiment of the present invention, each of the spherical elastic bodies 41, 42 has a simple spherical shape and rotates, so that salt, sand, dirt, etc. are unlikely to adhere to each of the spherical elastic bodies 41, 42. Furthermore, the spherical crown-shaped recess 34 in which each of the spherical elastic bodies 41, 42 is held is spherical crown-shaped, the cross-sectional shape of the round bottom groove 27 is arc-shaped, and each of the spherical elastic bodies 41, 42 is held between the spherical crown-shaped recess 34 and the round bottom groove 27 with some play, so that water around the propeller unit 21 flows easily and smoothly between each of the spherical elastic bodies 41, 42 and each of the spherical crown-shaped recesses 34, and between each of the spherical elastic bodies 41, 42 and each of the round bottom grooves 27. Therefore, salt, sand, dirt, etc., which has entered between each of the spherical elastic bodies 41, 42 and each of the spherical crown-shaped recesses 34, or between each of the spherical elastic bodies 41, 42 and each of the round-bottom grooves 27, is discharged by the water flow to the outside of the propeller unit 21. As a result, salt, sand, dirt, etc. are less likely to accumulate around the spherical elastic bodies 41, 42 (inside the spherical crown-shaped recesses 34 or the round-bottom grooves 27, etc.). This makes it possible to suppress a decrease in the shock absorbing function of the spherical elastic bodies 41, 42, which would be caused by salt, sand, dirt, etc. adhering to the spherical elastic bodies 41, 42 or by salt, sand, dirt, etc. accumulating around the spherical elastic bodies 41, 42, thereby inhibiting the elastic deformation of the spherical elastic bodies 41, 42.

[0045] Moreover, in the propeller unit 21 of the first embodiment of the present invention, each of the spherical elastic bodies 41, 42 is spherical and has a simple shape. Therefore, each of the spherical elastic bodies 41, 42 is easy to manufacture and is inexpensive. Commercially available rubber balls can also be used as each of the spherical elastic bodies 41, 42. Each of the annular elastic bodies 43 also has a simple shape and is inexpensive. Therefore, the economic burden on the user is small when replacing the deteriorated or damaged spherical elastic body 41 or 42, or the annular elastic body 43, with a new one. Thus, according to the propeller unit 21 of the first embodiment of the present invention, the economic burden on the user can be reduced when performing maintenance on the propeller unit 21.

[0046] In addition, because the spherical elastic bodies 41, 42 are easy to manufacture and inexpensive, various spherical elastic bodies with different sizes or hardness can be easily manufactured or procured. Therefore, a spherical elastic body having an optimal size or hardness can be easily selected depending on the size or propeller pitch of the propeller 22 to be attached to the outboard motor 1.

[0047] Here, a method of assembling the propeller unit 21 and mounting the propeller unit 21 to the propeller shaft 9 will be described. In Fig. 2, (1) first, the annular elastic bodies 43 are mounted in the respective annular grooves 35 of the cylindrical member 31. The annular elastic bodies 43 are annular elastic bodies such as O-rings, for example, and can be easily mounted in the annular grooves 35. (2) Next, the spherical elastic bodies 41, 42 are placed in the respective spherical crown-shaped recesses 34 of the cylindrical member 31. At this time, the spherical elastic bodies 41, 42 are adhered to the respective spherical crown-shaped recesses 34 with an adhesive or the like so that the spherical elastic bodies 41, 42 do not fall out of the spherical crown-shaped recesses 34 during the assembly work. In addition, when the outboard motor is in use, it is necessary that each of the spherical elastic bodies 41, 42 be able to rotate between the spherical crown recess 34 and the round bottom groove 27. Therefore, for example, an adhesive with extremely weak adhesive strength or an adhesive that dissolves in water and loses adhesive strength is used as the adhesive for bonding each of the spherical elastic bodies 41, 42 to each of the spherical crown recesses 34 during assembly. (3) Next, the cylindrical member 31 with the annular elastic body 43 attached and the spherical elastic bodies 41, 42 placed thereon is inserted into the insertion hole 24 of the hub 23 of the propeller 22 from the front of the hub 23, thereby attaching the cylindrical member 31, each of the spherical elastic bodies 41, 42 and the annular elastic body 43 to the propeller 22. (4) Next, the front spacer 12 is attached to the rear end of the propeller shaft 9. (5) Next, the propeller 22 with the cylindrical member 31 and the like attached thereto is attached to the rear end of the propeller shaft 9. (6) Next, the rear spacer 13 is attached to the rear end of the propeller shaft 9. (7) Next, the nut 14 is fastened to the rear end of the propeller shaft 9.

[0048] According to the propeller unit 21 of the first embodiment of the present invention, the propeller unit 21 can be easily assembled. That is, in some conventional propeller units, when a damper member having a function of absorbing the shock between the propeller shaft and the propeller is attached to the propeller unit, the damper member needs to be press-fitted into the propeller unit, and in this press-fitting process, a special press-fitting tool must be used or the damper member must be heated. In contrast, in the propeller unit 21 of the first embodiment of the present invention, the propeller unit 21 can be assembled by attaching each of the easily attachable annular elastic bodies 43 to each of the annular grooves 35 of the cylindrical member 31, placing each of the spherical elastic bodies 41, 42 in each of the spherical crown-shaped recesses 34 of the cylindrical member 31, and then inserting the cylindrical member 31 into the insertion hole 24 of the hub 23. No special press-fitting tools are required for mounting each annular elastic body 43 in cylindrical member 31, placing each spherical elastic body 41, 42 in cylindrical member 31, or inserting it into insertion hole 24 of cylindrical member 31, and there is no need to heat annular elastic body 43 or spherical elastic bodies 41, 42. Thus, according to propeller unit 21 of the first embodiment of the present invention, propeller unit 21 can be assembled more easily than conventional propeller units that require special press-fitting tools or heating of the damper member to mount the damper member. EXAMPLES

[0049] Fig. 7 shows a cross section of a propeller unit 51 according to a second embodiment of the present invention at the same position as Fig. 2. Fig. 8 shows a cross section of the propeller unit 51 taken along the section line VIII-VIII in Fig. 7 as seen from the front. Note that blades 28 are not shown in Fig. 8. Fig. 9 shows a cylindrical member 52 according to the second embodiment of the present invention as seen from the upper left rear side. Note that in the propeller unit 51 of the second embodiment, the same components as those in the propeller unit 21 of the first embodiment are denoted by the same reference numerals, and their description will be simplified or omitted.

[0050] As can be seen by comparing Figures 4 and 8, propeller unit 51 of the second embodiment has a plurality of round convex portions 53 instead of the plurality of high hardness spherical elastomer bodies 42 and the plurality of spherical crown-shaped concave portions 34 corresponding to the plurality of high hardness spherical elastomer bodies 42 in propeller unit 21 of the first embodiment.

[0051] Each of the round projections 53 has a function of transmitting the rotation of the propeller shaft 9 to the propeller 22. As shown in FIG. 9, each of the round projections 53 projects radially outward from the outer circumferential surface of the front portion of the cylindrical member 52. Each of the round projections 53 has a substantially semicircular cross-sectional shape and extends in a direction parallel to the axis of the propeller shaft 9. As shown in FIG. 7, the front end of each of the round projections 53 reaches the front end of the cylindrical member 52. The rear end of each of the round projections 53 has a shape of a quarter sphere (a sphere divided into four equal parts by two planes including the center). In this embodiment, each of the round projections 53 is integrally formed with the cylindrical member 52 by molding or the like, and is formed of a metal material such as stainless steel or brass. Each of the round projections 53 may be formed by joining a member formed of a metal material to the cylindrical member 52 by welding or the like.

[0052] 8, in this embodiment, three round protrusions 53 are disposed at equal intervals (120 degree intervals) around the entire circumference of the cylindrical member 52. In this embodiment, the low hardness spherical elastic bodies 41 and the round protrusions 53 are disposed alternately one by one in the circumferential direction of the cylindrical member 52.

[0053] The tip end portions of the three round convex portions 53 are located in three round bottom groove portions 27 arranged at 120 degree intervals among six round bottom groove portions 27 arranged at 60 degree intervals on the inner peripheral surface of the front portion of the insertion hole 24 of the hub 23. As shown in FIG. 8, each round convex portion 53 is formed so that its cross-sectional shape is an arc shape that is a part of a circle having a diameter D5 smaller than the diameter D1 of the low hardness spherical elastic body 41. The diameter D5 of the circle corresponding to the arc shape of the cross-sectional shape of each round convex portion 53 is smaller than the diameter D4 of the circle corresponding to the arc shape of the cross-sectional shape of each round bottom groove portion 27 of the hub 23. The tip end portions of each round convex portion 53 are inserted into the round bottom groove portion 27 with some play. The round convex portion 53 is a specific example of a "convex portion", and the spherical crown-shaped recess portion 34 corresponding to the round convex portion 53 is a specific example of a "third recess portion".

[0054] The propeller unit 51 of the second embodiment has a function of propelling the ship by the rotation of the propeller 22, as well as a shock absorbing function by the spherical elastic bodies, a function of inhibiting deterioration and damage of the spherical elastic bodies, and a shock absorbing function by the ring-shaped elastic bodies. The function of inhibiting deterioration and damage of the spherical elastic bodies, and the shock absorbing function by the ring-shaped elastic bodies are similar to those in the propeller unit 21 of the first embodiment.

[0055] The impact absorption function of the spherical elastic bodies in the propeller unit 51 of the second embodiment will be described. In FIG. 8, when the ship starts moving forward, the power of the power source 4 is transmitted to the propeller shaft 9 via the drive shaft 6 and the gear mechanism, and the propeller shaft 9 and the cylindrical member 31 start rotating in the counterclockwise direction (the direction of the arrow F in FIG. 8), first, the portion of each spherical elastic body 41 at position P1 is pressed against the spherical crown-shaped recess 34, and then the portion of each spherical elastic body 41 at position P2 presses the round-bottom groove portion 27. At this time, each spherical elastic body 41 is sandwiched between the spherical crown-shaped recess 34 and the round-bottom groove portion 27 and pressed, and compressed. As a result, the impact between the propeller shaft 9 (cylindrical member 31) and the propeller 22 is absorbed by each spherical elastic body 41. When each spherical elastic body 41 is compressed to a certain extent in this way, the portion of each round convex portion 53 at position P3 presses the round-bottom groove portion 27. While the propeller shaft 9 and the cylindrical member 31 are rotating counterclockwise, the rotation of the propeller shaft 9 and the cylindrical member 31 is transmitted to the propeller 22 by each of the spherical elastic bodies 41 and each of the round protrusions 53 .

[0056] 8, when the ship starts to move backward and the propeller shaft 9 and the cylindrical member 31 start to rotate in the clockwise direction (the direction of the arrow R in FIG. 8), first, the portion of each spherical elastic body 41 at position Q1 is pressed against the spherical crown-shaped recess 34, and then the portion of each spherical elastic body 41 at position Q2 presses against the round-bottom groove 27. At this time, each spherical elastic body 41 is sandwiched between the spherical crown-shaped recess 34 and the round-bottom groove 27 and pressed, and compressed. As a result, the impact between the propeller shaft 9 (cylindrical member 31) and the propeller 22 is absorbed by each spherical elastic body 41. When each spherical elastic body 41 is compressed to a certain extent in this way, the portion of each round convex portion 53 at position Q3 presses against the round-bottom groove 27. While the propeller shaft 9 and the cylindrical member 31 are rotating in the clockwise direction, the rotation of the propeller shaft 9 and the cylindrical member 31 is transmitted to the propeller 22 by each of the spherical elastic bodies 41 and each of the round protrusions 53 .

[0057] In this way, when the torque of the rotation of the propeller shaft 9 fluctuates when the vessel starts to move forward or backward, when the vessel reverses its direction of travel, or when it rapidly accelerates or decelerates, the impact between the propeller shaft 9 (cylindrical member 31) and the propeller 22 is absorbed by each of the spherical elastic bodies 41. This makes it possible to mitigate the impact between the propeller shaft 9 and the propeller 22 caused by torque fluctuations or the like.

[0058] Furthermore, while the propeller shaft 9 and the tubular member 31 are rotating, the round convex portions 53 formed from a metal material press against the round bottom groove portions 27, thereby transmitting the rotation of the propeller shaft 9 and the tubular member 31 to the propeller 22. Since the round convex portions 53 have a harder hardness than the high-hardness spherical elastic bodies 42 in the first embodiment, even when the torque of the rotation of the propeller shaft 9 is large, the rotation of the propeller shaft 9 can be reliably transmitted to the propeller 22 via the round convex portions 53. Therefore, the propeller unit 51 of the second embodiment can be suitably used in an outboard motor equipped with a high-torque, high-output power source.

[0059] Furthermore, the propeller unit 51 of the second embodiment, similar to the propeller unit 21 of the first embodiment, has the following advantages: by changing the orientation of each spherical elastic body 41, it is possible to prevent repeated concentration of stress at the same location on the spherical elastic bodies 41, thereby preventing premature deterioration and breakage of the spherical elastic bodies 41; it is possible to prevent a decrease in the shock absorbing function of the spherical elastic bodies 41 due to the accumulation of salt, sand, debris, etc. around the spherical elastic bodies 41; it is possible to reduce the economic burden on the user when performing maintenance on the propeller unit 51; it is possible to easily select an optimal spherical elastic body depending on the size or propeller pitch of the propeller 22 to be attached to the outboard motor 1; and it is possible to easily assemble the propeller unit 51.

[0060] In addition, the spherical elastic bodies 41, 42 in the first embodiment may be substantially spherical from the viewpoint of facilitating rotation, and may be, for example, an icosahedron or a 32-sided body. The elastic body may be cylindrical, as in the case of the cylindrical elastic body 63 placed in the round-bottom recess 62 formed on the outer circumferential surface of the front part of the cylindrical member 61 shown in FIG. 10. The cylindrical elastic body 63 is disposed so that its axis is parallel to the axis of the propeller shaft. In addition, in order to facilitate rotation of the cylindrical elastic body 63, it is preferable to shorten the axial dimension of the cylindrical elastic body 63.

[0061] In the first embodiment, the total number of the spherical elastic bodies is not limited to six, but may be three, four, five, or seven or more. In the second embodiment, the number of the round protrusions 53 is not limited to three, but may be one, two, or four or more.

[0062] Furthermore, in the first embodiment described above, the ratio in number of low hardness spherical elastomers 41 to high hardness spherical elastomers 42 is 1:1, but the ratio in number of low hardness spherical elastomers 41 to high hardness spherical elastomers 42 is not limited to this.

[0063] In the first embodiment described above, the diameter D1 of the low hardness spherical elastomer 41 is larger than the diameter D2 of the high hardness spherical elastomer 42. However, it is also possible to make the diameters of all the spherical elastomers the same, make the diameter of the sphere corresponding to the spherical crown shape of each spherical crown-shaped recess 34 corresponding to the low hardness spherical elastomer 41 smaller than the diameter of the sphere corresponding to the spherical crown shape of each spherical crown-shaped recess 34 corresponding to the high hardness spherical elastomer 41, and make the diameter of the circle corresponding to the arc-shaped cross section of each round bottom groove 27 corresponding to the low hardness spherical elastomer 41 smaller than the diameter of the circle corresponding to the arc-shaped cross section of each round bottom groove 27 corresponding to the high hardness spherical elastomer 41.

[0064] In the first embodiment, all the spherical elastic bodies may have the same hardness, or three or more types of spherical elastic bodies each having a different hardness may be provided.

[0065] In addition, in each of the above embodiments, an example has been given in which the spherical crown-shaped recess 34 is formed in the tubular member 31 (52) and the round bottom groove 27 is formed in the hub 23, but it is also possible to form the round bottom groove 27 in the tubular member 31 (52) and the spherical crown-shaped recess 34 in the hub 23.

[0066] Furthermore, the propeller unit of the present invention is not limited to being applied to outboard motors, but can also be applied to other types of marine propulsion motors, such as inboard motors and inboard-outboard motors.

[0067] Furthermore, the present invention can be modified as appropriate within the scope that does not contradict the gist or concept of the invention that can be read from the claims and the entire specification, and propeller units with such modifications are also included in the technical concept of the present invention. [Explanation of symbols]

[0068] 1. Outboard motor (marine propulsion unit) 9. Propeller shaft 21, 51 Propeller unit 22 Propeller 23. Hub 24 Insertion hole 27 Round bottom groove portion (second recess, third recess) 28 Blades 31, 52, 61 Cylindrical member 34 Spherical crown recess (first recess) 41, 42 Spherical elastic body (elastic body) 43 Annular elastic body (buffer material) 53 Round convex part (convex part) 62 Round bottom recess (first recess) 63 Cylindrical elastic body (elastic body)

Claims

1. A propeller unit for a marine propulsion device, a propeller having a hub with an insertion hole formed in the center and a plurality of blades provided on the hub; a cylindrical member that is inserted into the insertion hole, has a propeller shaft inserted therein, and is non-rotatably coupled to the propeller shaft; a plurality of elastic bodies provided between the cylindrical member and the hub, the elastic bodies absorbing impact between the propeller shaft and the propeller and transmitting rotation of the propeller shaft to the propeller, the cylindrical member is inserted into the insertion hole with some play so as to be movable in a circumferential direction relative to the hub, A plurality of first recesses are formed in an outer peripheral surface of the cylindrical member so as to be aligned in a circumferential direction, A plurality of second recesses are formed on an inner peripheral surface of the insertion hole so as to be aligned in a circumferential direction and to face the plurality of first recesses, respectively; Each of the elastic bodies is formed in a spherical shape, a first portion of the elastic body is located in the first recess, a second portion of the elastic body is located in the second recess, and the elastic body is rotatably held between the first recess and the second recess which face each other, a groove extending in a direction parallel to an axis of the propeller shaft and having a cross-sectional shape of an arc that is a part of a circle having a diameter larger than the diameter of the elastic body placed in the other recess, the groove being a groove formed in a direction parallel to an axis of the propeller shaft and having a cross-sectional shape of an arc that is a part of a circle having a diameter larger than the diameter of the elastic body placed in the other recess.

2. A propeller unit for a marine propulsion device, comprising: a propeller having a hub with an insertion hole formed in the center and a plurality of blades provided on the hub; a cylindrical member that is inserted into the insertion hole, has a propeller shaft inserted therein, and is non-rotatably coupled to the propeller shaft; a plurality of elastic bodies provided between the cylindrical member and the hub, the elastic bodies absorbing impact between the propeller shaft and the propeller and transmitting rotation of the propeller shaft to the propeller, the cylindrical member is inserted into the insertion hole with some play so as to be movable in a circumferential direction relative to the hub, A plurality of first recesses are formed in an outer peripheral surface of the cylindrical member so as to be aligned in a circumferential direction, A plurality of second recesses are formed on an inner peripheral surface of the insertion hole so as to be aligned in a circumferential direction and to face the plurality of first recesses, respectively; Each of the elastic bodies is formed in a spherical or cylindrical shape, a first portion of the elastic body is located in the first recess, a second portion of the elastic body is located in the second recess, and the elastic body is rotatably held between the first recess and the second recess which face each other, a protrusion protruding radially outward is provided on an outer peripheral surface of the cylindrical member, a third recess is provided on an inner peripheral surface of the insertion hole so as to correspond to the protrusion, and a tip portion of the protrusion is positioned within the third recess.

3. A propeller unit for a marine propulsion device, comprising: a propeller having a hub with an insertion hole formed in the center and a plurality of blades provided on the hub; a cylindrical member that is inserted into the insertion hole, has a propeller shaft inserted therein, and is non-rotatably coupled to the propeller shaft; a plurality of elastic bodies provided between the cylindrical member and the hub, the elastic bodies absorbing impact between the propeller shaft and the propeller and transmitting rotation of the propeller shaft to the propeller, the cylindrical member is inserted into the insertion hole with some play so as to be movable in a circumferential direction relative to the hub, A plurality of first recesses are formed in an outer peripheral surface of the cylindrical member so as to be aligned in a circumferential direction, A plurality of second recesses are formed on an inner peripheral surface of the insertion hole so as to be aligned in a circumferential direction and to face the plurality of first recesses, respectively; Each of the elastic bodies is formed in a spherical or cylindrical shape, a first portion of the elastic body is located in the first recess, a second portion of the elastic body is located in the second recess, and the elastic body is rotatably held between the first recess and the second recess which face each other, a buffer member formed in an annular shape and made of an elastic material is provided between the cylindrical member and the hub; a cushioning member disposed on the outer circumferential side of the other axial side of the cylindrical member; and a cushioning member disposed on the outer circumferential side of the other axial side of the cylindrical member.

4. 4. The propeller unit according to claim 1, wherein the plurality of elastic bodies include a first elastic body having a first hardness set thereto, and a second elastic body having a second hardness set thereto that is higher than the first hardness.

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