Damper unit for vessel propulsion apparatus, propeller for vessel propulsion apparatus, and vessel propulsion apparatus

A damper unit includes a first damper arranged to transmit a torque around a rotation axis transmitted from an input member side to an output member side, an intermediate member arranged to transmit a torque around the rotation axis transmitted from the first damper to the output member side, and a second damper arranged to transmit a torque around the rotation axis transmitted from the intermediate member to the output member side, wherein at least a portion of the second damper is disposed on a straight line that passes through the first damper and is parallel or substantially parallel to the rotation axis.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a damper unit for a vessel propulsion apparatus, a propeller for a vessel propulsion apparatus including the damper unit, and a vessel propulsion apparatus including the damper unit.

2. Description of the Related Art

A propeller for a vessel propulsion apparatus is mounted on a propeller shaft via a propeller damper (damper unit). The damper unit transmits a torque between the propeller and the propeller shaft and absorbs a vibration between the propeller and the propeller shaft. An impact (shift shock) accompanying engagement/disengagement of a dog clutch and an impact accompanying collision of the propeller and an underwater obstacle are absorbed by the damper unit. The damper unit thus contributes to the protection of parts, reduction of impact noise, and improvement of maneuverability.

A damper unit according to U.S. Patent Application Publication No. 2011/0212657 A1 includes two dampers (a main damper and a sub damper) disposed in parallel. In a case in which a torque applied to the propeller or the propeller shaft is small, only the main damper, which is softer than the sub damper, transmits the torque. When the torque applied to the propeller or the propeller shaft increases, the torque is transmitted by two parallel paths (a path via the main damper and a path via the sub damper). That is, when the torque applied to the propeller or the propeller shaft increases, both dampers transmit the torque.

SUMMARY OF THE INVENTION

A performance of the damper unit is defined by a maximum operating angle and a maximum torque. The operating angle is an elastic deformation amount of the damper unit in a circumferential direction (in the case of a propeller damper, a relative rotation angle of the propeller and the propeller shaft). The maximum operating angle is a maximum value of the operating angle at which the damper unit does not break, undergo plastic deformation, or slip with respect to the propeller and the propeller shaft. The maximum torque is a magnitude of the torque transmitted to the damper unit in state in which the damper unit is twisted at the maximum operating angle. The greater both the maximum operating angle and the maximum torque, the higher the performance of the damper unit.

With the damper unit according to U.S. Patent Application Publication No. 2011/0212657 A1, when the sub damper becomes coupled to both the propeller and the propeller shaft when the torque applied to the propeller, etc., becomes large, the main damper is coupled to both the propeller and the propeller shaft regardless of the magnitude of the torque. The maximum operating angle of the damper unit as a whole is thus restricted by the main damper and it is difficult to significantly improve the performance of the damper unit.

A preferred embodiment of the present invention thus provides a damper unit for a vessel propulsion apparatus that transmits a torque between an input member and an output member, which are disposed on a transmission path in which a rotation of a prime mover is transmitted to a plurality of blades, and that absorbs a vibration between the input member and the output member. The damper unit includes a first damper arranged to transmit a torque around a rotation axis, transmitted from an input member side, to an output member side, an intermediate member arranged to transmit a torque around the rotation axis, transmitted from the first damper, to the output member side, and a second damper arranged to transmit the torque around the rotation axis, transmitted from the intermediate member, to the output member side wherein at least a portion of the second damper is disposed on a straight line that passes through the first damper and is parallel or substantially parallel to the rotation axis.

With this arrangement of the present preferred embodiment of the present invention, the first damper and the second damper are disposed in series on the transmission path transmitting the rotation of the prime mover to the plurality of blades. The torque around the rotation axis transmitted to the input member is transmitted to the output member via the first damper, the intermediate member, and the second damper, in that order. Oppositely, a torque around the rotation axis transmitted to the output member is transmitted to the input member via the second damper, the intermediate member, and the first damper, in that order.

The first damper and the second damper are disposed in series and, therefore, torques of substantially equal magnitudes are applied to the first damper and the second damper, and the first damper and the second damper deform elastically in a circumferential direction (direction around the rotation axis). A maximum operating angle of the damper unit (maximum elastic deformation amount of the damper unit around the rotation axis) is a sum of a maximum operating angle of the first damper and a maximum operating angle of the second damper. The maximum operating angle of the damper unit can thus be increased while maintaining a maximum torque (torque corresponding to the maximum operating angle) at not less than a fixed value.

Further, at least a portion of the second damper is disposed on the straight line passing through the first damper and is parallel or substantially parallel to the rotation axis and therefore, at least a portion of the second damper and the first damper are aligned in an axial direction (direction along the rotation axis). The damper unit can thus be made smaller in outer diameter than in a case in which the first damper and the second damper are disposed concentrically. Therefore, in a case in which the prime mover is an internal combustion engine and the damper unit is disposed in an interior of a propeller that defines an exhaust passage, any reduction of an area of the exhaust passage can be minimized. Lowering of an output of the vessel propulsion apparatus can thus be minimized.

In a preferred embodiment of the present invention, the damper unit may further include a main stopper arranged to restrict a relative rotation of the input member and the output member to cause the input member and the output member to rotate integrally when the torque around the rotation axis transmitted to the damper unit exceeds a predetermined value.

With this arrangement of the present preferred embodiment of the present invention, when the torque is applied to the damper unit, the first damper and the second damper twist elastically in the circumferential direction (direction around the rotation axis) and the input member and the output member undergo relative rotation. When the torque applied to the damper unit exceeds the predetermined value, the input member and the output member are coupled together by the main stopper and the relative rotation of the input member and the output member is restricted by the main stopper. The input member and the output member thus rotate integrally. The elastic deformations of the first damper and the second damper are thus restricted by the main stopper and twist amounts of the first damper and the second damper are limited. An operating angle of the damper unit can thus be prevented from exceeding the maximum operating angle.

In a preferred embodiment of the present invention, the damper unit may further include a sub stopper arranged to restrict a relative rotation of one of either the input member or the output member with respect to the intermediate member to cause one of either the input member or the output member to rotate integrally with the intermediate member when the torque around the rotation axis transmitted to the damper unit exceeds a predetermined value.

With this arrangement of the present preferred embodiment of the present invention, when the torque applied to the damper unit exceeds the predetermined value, the relative rotation of one of either the input member or the output member with respect to the intermediate member is restricted by the sub stopper and one of either the input member or the output member rotates integrally with the intermediate member. The elastic deformations of the first damper and the second damper are thus restricted by the sub stopper and the twist amounts of the first damper and the second damper are limited. That is, the twist amounts of the first damper and the second damper are restricted by the two stoppers (the main stopper and the sub stopper) and the operating angle of the damper unit can thus be reliably prevented from exceeding the maximum operating angle.

In a preferred embodiment of the present invention, the first damper, the intermediate member, and the second damper may be housed together in a housing. The housing is preferably an integral member. In this case, it suffices that at least a portion of the first damper is housed inside the housing. The same applies to the intermediate member and the second damper.

In a preferred embodiment of the present invention, one of either of the first damper and the second damper may be surrounded by the intermediate member and the other of the first damper and the second damper may surround the intermediate member. Also, each of the first damper and the second damper may surround the intermediate member. Also, each of the first damper and the second damper may be surrounded by the intermediate member.

In a case in which one of either of the first damper and the second damper is surrounded by the intermediate member and the other of the first damper and the second damper surrounds the intermediate member, the intermediate member may include an upstream cylindrical portion coupled to the first damper and surrounding the first damper, and a downstream cylindrical portion coupled to the second damper and surrounded by the second damper and having a smaller outer diameter than the upstream cylindrical portion. Also, the intermediate member may include, in addition to the upstream cylindrical portion and the downstream cylindrical portion, a cylindrical step portion extending from the upstream cylindrical portion to the downstream cylindrical portion and defining a step interposed between the first damper and the second damper.

With this arrangement of the present preferred embodiment of the present invention, the first damper is surrounded by the upstream cylindrical portion of the intermediate member and the second damper surrounds the downstream cylindrical portion of the intermediate member. The outer diameter of the downstream cylindrical portion is smaller than an outer diameter and an inner diameter of the upstream cylindrical portion. In a case in which a thickness of the second damper is fixed, when the outer diameter of the downstream cylindrical portion increases, an outer diameter of the second damper also increases accordingly. Therefore, by making the outer diameter of the downstream cylindrical portion smaller than the upstream cylindrical portion, the outer diameter of the second damper can be made small. Enlargement of the damper unit can thus be minimized.

Another preferred embodiment of the present invention provides a propeller for a vessel propulsion apparatus including the damper unit and a propeller member. The propeller member includes an inner cylinder as the output member surrounding the damper unit, an outer cylinder as a housing surrounding the damper unit and the inner cylinder, and a plurality of blades extending outward from the outer cylinder.

With this arrangement of the present preferred embodiment of the present invention, the propeller member that generates a thrust by the plurality of blades is mounted on a propeller shaft via the damper unit. An impact (shift shock) accompanying engagement/disengagement of a dog clutch and an impact accompanying collision of the propeller and an underwater obstacle are absorbed by the damper unit. As mentioned above, the damper unit can increase the maximum operating angle while maintaining the maximum torque at not less than a fixed value. The propeller can thus transmit a greater torque between the propeller member and the propeller shaft by the damper unit. Further, the propeller can caused the impacts applied to the propeller member and the propeller shaft to be reliably absorbed by the damper unit.

In another preferred embodiment of the present invention, the propeller may further include a front member mounted on a propeller shaft, which is rotatable around the rotation axis, and supporting a front end portion of the inner cylinder and a rear member mounted on the propeller shaft and supporting a rear end portion of the inner cylinder.

With this arrangement of the present preferred embodiment of the present invention, the front member and the rear member are mounted on the propeller shaft. The front end portion of the inner cylinder of the propeller member is supported by the propeller shaft via the front member and the rear end portion of the inner cylinder of the propeller member is supported by the propeller shaft via the rear member. That is, the opposite end portions of the inner cylinder are supported by the propeller shaft via the front member and the rear member. An attitude of the inner cylinder can thus be stabilized better than in a case in which just an end portion at one side of the inner cylinder is supported. The propeller member can thus be rotated with stability.

In another preferred embodiment of the present invention, the front member may include a front pressed portion that is pressed forward by the inner cylinder and the rear member may include a rear pressed portion that is pressed rearward by the inner cylinder.

With this arrangement of the present preferred embodiment of the present invention, when the propeller member generates a thrust in a forward drive direction, the front pressed portion of the front member is pressed forward by the inner cylinder and the thrust in the forward drive direction is transmitted from the inner cylinder to the propeller shaft via the front member. Oppositely, when the propeller member generates a thrust in a reverse drive direction, the rear pressed portion of the rear member is pressed rearward by the inner cylinder and the thrust in the reverse drive direction is transmitted from the inner cylinder to the propeller shaft via the rear member. As a result, thrusts are transmitted to a hull and the hull is propelled.

In another preferred embodiment of the present invention, the inner cylinder may entirely house the first damper, the intermediate member, and the second damper.

Yet another preferred embodiment of the present invention provides a vessel propulsion apparatus including a prime mover, a driveshaft rotatable around a drive axis, extending in an up/down direction, and to which a rotation from the prime mover is transmitted, a propeller shaft rotatable around a propeller axis, the propeller axis intersecting the drive axis, and to which a rotation from the driveshaft is transmitted, a propeller member rotatable around the propeller axis and to which a rotation from the propeller shaft is transmitted, and the damper unit disposed on a transmission path in which the rotation of the prime mover is transmitted to the propeller member via the driveshaft and the propeller shaft.

With this arrangement of the present preferred embodiment of the present invention, the rotation of the prime mover is transmitted to the propeller member via the driveshaft and the propeller shaft, in that order. The damper unit is disposed on the transmission path transmitting the rotation of the prime mover to the propeller member via the driveshaft and the propeller shaft. A torque of the prime mover is thus transmitted to the propeller member via the damper unit, the driveshaft, and the propeller shaft. Further, an impact generated in the transmission path is absorbed by the damper unit.

In the yet another preferred embodiment of the present invention, the damper unit may be disposed on the propeller axis. In this case, the damper unit may be housed inside the propeller member or may be housed inside a casing that houses the driveshaft and the propeller shaft.

In another preferred embodiment of the present invention, the damper unit may be disposed on the drive axis. In this case, the damper unit may be housed inside a casing that houses the driveshaft and the propeller shaft.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1is a side view of a vessel propulsion apparatus1according to a first preferred embodiment of the present invention.

The vessel propulsion apparatus1includes a bracket2mountable on a rear portion of a hull H1and an outboard motor3supported by the bracket2in a manner enabling rotation around a steering axis extending in an up/down direction.

The outboard motor3includes an engine4generating a motive power, a driveshaft5connected to the engine4, a forward/reverse drive switching mechanism6connected to the driveshaft5, a propeller shaft7connected to the forward/reverse drive switching mechanism6, and a propeller8connected to the propeller shaft7. Further, the outboard motor3includes an engine cover9housing the engine4and a casing10housing the driveshaft5, etc. The casing10includes an upper case11disposed below the engine cover9and a lower case12disposed below the upper case11.

The engine4is an internal combustion engine that includes a crankshaft13rotatable around a crank axis Ac extending in the up/down direction. The engine4is an example of a prime mover. The prime mover is not restricted to the engine4and may be an electric motor or may be the engine4and an electric motor. The driveshaft5, the forward/reverse drive switching mechanism.6, and the propeller shaft7are disposed on a transmission path transmitting a rotation of the engine4(rotation of the crankshaft13) to a plurality of blades31of the propeller8. The rotation of the engine4is transmitted to the propeller8via the driveshaft5, the forward/reverse drive switching mechanism6, and the propeller shaft7, in that order. A thrust that propels the hull H1is thus generated.

The driveshaft5extends downward from the engine4. The driveshaft5extends in the up/down direction inside the upper case11and the lower case12. The driveshaft5is rotatable around a drive axis Ad (central axis of the driveshaft5) with respect to the casing10. An impeller of a water pump WP that feeds water outside the outboard motor3to the engine4rotates around the drive axis Ad together with the driveshaft5. An upper end portion of the driveshaft5is connected to the engine4and a lower end portion of the driveshaft5is connected to the forward/reverse drive switching mechanism6. The driveshaft5includes a plurality of shafts disposed on the drive axis Ad.

The propeller shaft7extends rearward from the forward/reverse drive switching mechanism6. The propeller shaft7extends in a front/rear direction inside the lower case12. The propeller shaft7is rotatable around a propeller axis Ap (central axis of the propeller shaft7) with respect to the casing10. A rear end portion of the propeller shaft7projects rearward from the lower case12. The propeller8is coupled to the rear end portion of the propeller shaft7. The propeller8rotates around the propeller axis Ap together with the propeller shaft7.

The forward/reverse drive switching mechanism6as a speed reduction mechanism includes a pinion14rotating around the drive axis Ad together with the driveshaft5, a front gear15and a rear gear16engaged with the pinion14, and a cylindrical dog clutch17engaged selectively with one of either of the front gear15and the rear gear16. The outboard motor3includes a shift actuator18disposed inside the engine cover9and a shift rod19connecting the shift actuator18and the dog clutch17. The forward/reverse drive switching mechanism6is selectively switched to one state among a forward drive state, a reverse drive state, and a neutral state.

The pinion14, the front gear15, and the rear gear16are bevel gears. The pinion14is coupled in a downward facing attitude to the lower end portion of the driveshaft5, and the front gear15and the rear gear15are held in the lower case12. The front gear15is engaged with the pinion14at a front of the drive axis Ad and the rear gear16is engaged with the pinion14at a rear of the drive axis Ad. The front gear15and the rear gear16are disposed at an interval in the front/rear direction. The dog clutch17is disposed between the front gear15and the rear gear16. The propeller shaft7penetrates through the front gear15, the rear gear16, and the dog clutch17, disposed on the propeller axis Ap, in the front/rear direction. The front gear15and the rear gear16are rotatable around the propeller axis Ap with respect to the casing10and the propeller shaft7.

An inner circumferential portion of the dog clutch17is spline-coupled with an outer circumferential portion of the propeller shaft7. The dog clutch17is thus movable in the front/rear direction with respect to the propeller shaft7and rotates around the propeller axis Ap together with the propeller shaft7. The dog clutch17is movable with respect to the propeller shaft7between a forward drive position at which a front end portion of the dog clutch17engages with the front gear15and a reverse drive position at which a rear end portion of the dog clutch17engages with the rear gear16. A position between the front drive position and the reverse drive position (position shown inFIG. 1) is a neutral position at which the dog clutch17is separated from both the front gear15and the rear gear16. The shift actuator18moves the dog clutch17to a shift position among the forward drive position, the reverse drive position, and the neutral position.

The driveshaft5is driven in a fixed rotation direction by the engine4. The pinion14rotates around the drive axis Ad together with the driveshaft5. The front gear15and the rear gear16rotate in mutually opposite directions in accompaniment with the rotation of the pinion14. In a state in which the dog clutch17is disposed at the forward drive position and the front gear15is rotating, the rotation of the front gear15is transmitted to the propeller shaft7via the dog clutch17. The propeller shaft7and the propeller8are thus rotated in a forward rotation direction (for example, clockwise as viewed from the rear of the propeller8) and a thrust that drives hull H1forward is generated. On the other hand, in a state in which the dog clutch17is disposed at the reverse drive position and the rear gear16is rotating, the rotation of the rear gear16is transmitted to the propeller shaft7via the dog clutch17. The propeller shaft7and the propeller8are thus rotated in a reverse rotation direction (a direction opposite to the forward rotation direction) and a thrust that drives hull H1in reverse is generated. Also, in a state in which the dog clutch17is disposed at the neutral position, the rotation of the driveshaft5is not transmitted to the propeller shaft7and the driveshaft5idles.

The outboard motor3includes an exhaust passage20by which an exhaust, generated at the engine4, is exhausted underwater from the propeller8. The exhaust passage20is connected to the engine4. The exhaust passage20extends downward from the engine4to the propeller shaft7and extends farther in the front/rear direction along the propeller shaft7. The exhaust passage20includes an exhaust outlet21that opens rearward at the propeller8. In a state in which the propeller8is disposed underwater, the exhaust outlet21is also disposed underwater. Therefore, in this state, the exhaust outlet21is blocked by water. The exhaust generated at the engine4flows into the exhaust passage20from an upstream end of the exhaust passage20. When an exhaust pressure inside the exhaust passage20increases, the water inside the exhaust outlet21is forced outside the propeller8by the exhaust and the exhaust inside the exhaust passage20is discharged underwater from the propeller8.

FIG. 2is a sectional view of the propeller shaft7and the propeller8.FIG. 3is a sectional view taken along line III-III inFIG. 2, andFIG. 4is a sectional view taken along line IV-IV inFIG. 2.FIG. 5is a sectional view taken along line V-V inFIG. 2, andFIG. 6is a sectional view taken along line VI-VI inFIG. 2. A section at an upper side of the propeller axis Ap inFIG. 2and a section at a lower side of the propeller axis Ap inFIG. 2are mutually orthogonal or substantially orthogonal sections (see line II-II shown inFIG. 5andFIG. 6). A free state in which a torque is not applied to a damper unit23is illustrated inFIG. 2toFIG. 6. In the following, the damper unit23in the free state shall be described unless noted otherwise.

As shown inFIG. 2, the propeller8includes a cylindrical propeller member22that generates a thrust and the cylindrical damper unit23that is detachably mounted on the propeller member22. The outboard motor3includes a washer W1and a nut N1that fix the propeller member22and the damper unit23to the rear end portion of the propeller shaft7and a pin P1that prevents loosening of the nut N1.

As shown inFIG. 2, the propeller8is detachably mounted on the rear end portion of the propeller shaft7. The rear end portion of the propeller shaft7includes a large diameter portion24, a tapered portion25, a small diameter portion26, and a bolt portion27that are columnar and extend in the front/rear direction along the propeller axis Ap. The large diameter portion24, the tapered portion25, the small diameter portion26, and the bolt portion27are aligned in that order in the front/rear direction from the front. The large diameter portion24is thicker than the small diameter portion26and the small diameter portion26is thicker than the bolt portion27. The tapered portion25extends from a rear end of the large diameter portion24to a front end of the small diameter portion26such that the tapered portion25is tapered toward the small diameter portion26.

As shown inFIG. 2, the propeller member22includes an inner cylinder28surrounding the damper unit23around the propeller axis Ap, and an outer cylinder29coaxially surrounding the inner cylinder28and spaced from the inner cylinder28in a radial direction (direction orthogonal or substantially orthogonal to the propeller axis Ap). Further, the propeller member22includes a plurality of ribs30coupling the inner cylinder28and the outer cylinder29at a plurality of positions separated in a circumferential direction (direction around the propeller axis Ap) and the plurality of blades31extending outward from the outer cylinder29. The damper unit23is disposed on the transmission path that transmits the rotation of the engine4to the plurality of blades31. The damper unit23transmits a torque around the propeller axis Ap between the propeller shaft7as an input member and the inner cylinder28as an output member and absorbs a vibration around the propeller axis Ap between the propeller shaft7and the inner cylinder28.

As shown inFIG. 2, the inner cylinder28of the propeller member22is housed inside the outer cylinder29of the propeller member22. A front end of the inner cylinder28is disposed at a position more rearward than a front end of the outer cylinder29and a rear end of the inner cylinder28is disposed at a position more forward than a rear end of the outer cylinder29. The plurality of ribs30are disposed between the inner cylinder28and the outer cylinder29at intervals in the circumferential direction (seeFIG. 4). Each rib30has a plate-shaped configuration extending radially from an outer circumferential surface of the inner cylinder28to an inner circumferential surface of the outer cylinder29. The plurality of blades31are disposed on a circumference of the outer cylinder29. The plurality of blades31are disposed at intervals in the circumferential direction. The inner cylinder28, the outer cylinder29, the ribs30, and the blades31may be a single integral member or may include a plurality of members integrally coupled. In either case, the inner cylinder28, the outer cylinder29, the ribs30, and the blades31rotate integrally around the propeller axis Ap. The plurality of blades31generate the thrust by rotating around the propeller axis Ap.

As shown inFIG. 2, the outer circumferential surface of the inner cylinder28and the inner circumferential surface of the outer cylinder29face each other at the radial interval. The plurality of ribs30are disposed at the intervals in the circumferential direction between the inner cylinder28and the outer cylinder29. The outer circumferential surface of the inner cylinder28, the inner circumferential surface of the outer cylinder29, and the plurality of ribs30define a portion of the exhaust passage20by which the exhaust generated at the engine4is discharged from the propeller8. Further, a rear end portion of the outer cylinder29defines the exhaust outlet21that is opened rearward. The exhaust generated at the engine4passes through an interior of the casing10and is guided into an interior of the propeller member22from a front of the propeller member22. The exhaust guided into the propeller member22from the casing10flows rearward through a cylindrical space between the inner cylinder28and the outer cylinder29and is discharged rearward from the rear end portion of the outer cylinder29. The exhaust generated at the engine4is thus discharged underwater from the propeller8.

As shown inFIG. 2, the damper unit23is disposed on the propeller axis Ap. The damper unit23includes a front spacer32, a sleeve33, an intermediate spacer34, and a rear spacer35that are cylindrical and are mounted on the propeller shaft7. Further, the damper unit23includes a cylindrical first damper36arranged to transmit the torque from the sleeve33to a downstream side (downstream side of the transmission path), a cylindrical intermediate member37arranged to transmit the torque from the first damper36to the downstream side, and a second damper38arranged to transmit the torque from the intermediate member37to the propeller member22.

As shown inFIG. 2, the front spacer32, the sleeve33, the intermediate spacer34, and the rear spacer35surround the propeller shaft7around the propeller axis Ap. The front spacer32, the sleeve33, the intermediate spacer34, and the rear spacer35are aligned in the front/rear direction in that order from the front. The sleeve33and the intermediate spacer34are disposed inside the inner cylinder28. The sleeve33is longer in the front/rear direction than the front spacer32, the intermediate spacer34, and the rear spacer35. Further, an outer diameter of the sleeve33is smaller than outer diameters of the front spacer32and the rear spacer35. Similarly, an outer diameter of the intermediate spacer34is smaller than outer diameters of the front spacer32and the rear spacer35.

As shown inFIG. 2, the sleeve33extends in the front/rear direction along the propeller axis Ap. A front end of the sleeve33is disposed farther to the rear than the front end of the inner cylinder28and a rear end of the sleeve33is disposed farther to the front than the rear end of the inner cylinder28. The sleeve33surrounds the small diameter portion26of the propeller shaft7around the propeller axis Ap. An inner circumferential portion of the sleeve33is spline-connected to an outer circumferential portion of the small diameter portion26. The sleeve33is thus movable in the axial direction (direction along the propeller axis Ap) with respect to the propeller shaft7and rotates together with the propeller shaft7around the propeller axis Ap. The torque transmitted to the propeller shaft7is transmitted to the sleeve33via male splines provided on the outer circumferential portion of the propeller shaft7and female splines provided on the inner circumferential portion of the sleeve33.

As shown inFIG. 2, the front spacer32is mounted on a front end portion of the inner cylinder28. An opening defined by the front end portion of the inner cylinder28is closed by the propeller shaft7and the front spacer32. Also, the rear spacer35is mounted on a rear end portion of the inner cylinder28. An opening defined by the rear end portion of the inner cylinder28is closed by the propeller shaft7and the rear spacer35. The front end portion of the inner cylinder28is supported by the front spacer32and the rear end portion of the inner cylinder28is supported by the rear spacer35. The front end portion and the rear end portion of the inner cylinder28are thus supported by the propeller shaft7via the front spacer32and the rear spacer35.

As shown inFIG. 2, the washer W1is disposed behind the rear spacer35. The nut N1is disposed behind the washer W1. Outer diameters of the washer W1and the nut N1are smaller than outer diameters of the inner cylinder28and the rear spacer35. The washer W1and the nut N1are mounted on the bolt portion27of the propeller shaft7. The front spacer32, the sleeve33, the intermediate spacer34, and the rear spacer35are pressed forward by the washer W1and the nut N1. Forward movement of the front spacer32with respect to the propeller shaft7is restricted by contact of an outer circumferential surface of the propeller shaft7and an inner circumferential surface of the front spacer32. The front spacer32, the sleeve33, the intermediate spacer34, and the rear spacer35are thus fixed to the propeller shaft7by the washer W1and the nut N1and rotate around the propeller axis Ap together with the propeller shaft7.

As shown inFIG. 2, the first damper36, the intermediate member37, and the second damper38are disposed inside the inner cylinder28. The inner cylinder28entirely houses the first damper36, the intermediate member37, and the second damper38. The first damper36, the intermediate member37, and the second damper38are thus housed inside the outer cylinder29as a housing. The first damper36, the intermediate member37, and the second damper38are disposed between the sleeve33and the inner cylinder28. The first damper36, the intermediate member37, and the second damper38surround the sleeve33around the propeller axis Ap. The first damper36is disposed in front of the second damper38. The first damper36is surrounded by the intermediate member37and the second damper38surrounds the intermediate member37. In regard to the front/rear direction, the first damper36, the intermediate member37, and the second damper38are disposed between the front spacer32and the rear spacer35.

As shown inFIG. 2, the intermediate member37is coupled to the sleeve33via an elastic body (first damper36) and is coupled to the inner cylinder28via an elastic body (second damper38). The intermediate member37is rotatable around the propeller axis Ap with respect to the sleeve33within an elastic range (a range not more than an elastic limit) of the first damper36. Also, the intermediate member37is rotatable around the propeller axis Ap with respect to the inner cylinder28within an elastic range of the second damper38. The first damper36transmits the torque around the propeller axis Ap between the sleeve33and the intermediate member37and absorbs a vibration around the propeller axis Ap between the sleeve33and the intermediate member37. Also, the second damper38transmits the torque around the propeller axis Ap between the intermediate member37and the inner cylinder28and absorbs a vibration around the propeller axis Ap between the intermediate member37and the inner cylinder28. The torque around the propeller axis Ap is thus transmitted between the propeller shaft7and the propeller member22via the damper unit23.

As shown inFIG. 2, the intermediate member37includes an inner circumferential surface and an outer circumferential surface that are step-shaped and change in diameter in a stepwise manner. The intermediate member37includes an upstream cylindrical portion39coupled to the first damper36, an annular step portion40defining a step at an intermediate portion of the intermediate member37in the front/rear direction, and a downstream cylindrical portion41coupled to the second damper38. The intermediate member37may include a plurality of members or may be a single integral member. A case in which the intermediate member37includes the plurality of members is shown inFIG. 2.

As shown inFIG. 2, the upstream cylindrical portion39surrounds the first damper36and the downstream cylindrical portion41is surrounded by the second damper38. The upstream cylindrical portion39and the downstream cylindrical portion41extend in the front/rear direction along the propeller axis Ap. The upstream cylindrical portion39is disposed farther to the front than the downstream cylindrical portion41. The step portion40extends from a rear end of the upstream cylindrical portion39to a front end of the downstream cylindrical portion41. An inner diameter of the upstream cylindrical portion39is greater than an outer diameter of the downstream cylindrical portion41. An inner diameter of the downstream cylindrical portion41is greater than the outer diameter of the sleeve33. The downstream cylindrical portion41surrounds the sleeve33at a radial interval.

As shown inFIG. 2, the upstream cylindrical portion39is disposed farther to the front than the second damper38and the downstream cylindrical portion41is disposed farther to the rear than the first damper36. The step portion40defines the step interposed between the first damper36and the second damper38. A rear end surface of the first damper36and a front end surface of the second damper38face the step portion40of the intermediate member37in the front/rear direction. The first damper36and the second damper38are aligned in the front/rear direction via the step portion40. A portion of the second damper38is disposed on a straight line L1passing through the first damper36and is parallel or substantially parallel to the propeller axis Ap.

As shown inFIG. 2, the first damper36and the second damper38are made of an elastic material, such as rubber or resin, etc. Elastic moduli of the first damper36and the second damper38may be equal to each other or may differ from each other. That is, the first damper36may be harder than the second damper38or may be softer than the second damper38or may have the same hardness as the second damper38.

As shown inFIG. 2, an inner circumferential portion of the first damper36is coupled to an outer circumferential portion of the sleeve33, for example, by adhesion, and an outer circumferential portion of the first damper36is coupled to an inner circumferential portion of the upstream cylindrical portion39, for example, by a tooth and groove engagement. Similarly, an inner circumferential portion of the second damper38is coupled to an outer circumferential portion of the downstream cylindrical portion41, for example, by adhesion, and an outer circumferential portion of the second damper38is coupled to an inner circumferential portion of the inner cylinder28, for example, by a tooth and groove engagement. The first damper36may be coupled to the sleeve33by a tooth and groove engagement and be coupled to the upstream cylindrical portion39by adhesion. Also, the first damper36may be coupled to the sleeve33by a tooth and groove engagement and be coupled to the upstream cylindrical portion39by a tooth and groove engagement. The same applies to the second damper38.

As shown inFIG. 3, the upstream cylindrical portion39includes an uneven inner circumferential surface provided with a plurality of radially projecting teeth43. The first damper36includes an uneven outer circumferential surface provided with a plurality of radially recessed grooves44. The plurality of teeth43are aligned at intervals in the circumferential direction and extend in the front/rear direction. Similarly, the plurality of grooves44are aligned at intervals in the circumferential direction and extend in the front/rear direction. The plurality of teeth43are respectively disposed inside the plurality of grooves44. A pair of tooth surfaces of a tooth43respectively contact a pair of inner surfaces of a groove44. The outer circumferential surface of the first damper36is placed in close contact with the inner circumferential surface of the upstream cylindrical portion39in a state in which the plurality of teeth43are engaged with the first damper36. As shown inFIG. 2, the inner circumferential surface of the upstream cylindrical portion39is tapered toward the rear end of the upstream cylindrical portion39. The first damper36is thus restricted in rearward movement by an inclination of the inner circumferential surface of the upstream cylindrical portion39.

As shown inFIG. 4, the inner cylinder28includes an uneven inner circumferential surface provided with the plurality of teeth43projecting radially. The second damper38includes an uneven outer circumferential surface provided with the plurality of grooves44that are recessed radially. The plurality of teeth43are aligned at intervals in the circumferential direction and extend in the front/rear direction. Similarly, the plurality of grooves44are aligned at intervals in the circumferential direction and extend in the front/rear direction. The plurality of teeth43are respectively disposed inside the plurality of grooves44. A pair of tooth surfaces of a tooth43respectively contact a pair of inner surfaces of a groove44. The outer circumferential surface of the second damper38is placed in close contact with the inner circumferential surface of the inner cylinder28in a state in which the plurality of teeth43are engaged with the second damper38. As shown inFIG. 2, the inner circumferential surface of the rear portion of the inner cylinder28is tapered toward the rear end of the inner cylinder28. The second damper38is thus restricted in rearward movement by an inclination of the inner circumferential surface of the inner cylinder28.

The inner circumferential portion of the first damper36rotates around the propeller axis Ap together with the sleeve33and the outer circumferential portion of the first damper36rotates around the propeller axis Ap together with the upstream cylindrical portion39. The inner circumferential portion of the second damper38rotates around the propeller axis Ap together with the downstream cylindrical portion41and the outer circumferential portion of the second damper38rotates around the propeller axis Ap together with the inner cylinder28. When the torque around the propeller axis Ap is applied to the first damper36, the first damper36deforms elastically in the circumferential direction, and the inner circumferential portion of the first damper36and the outer circumferential portion of the first damper36undergo relative movement in the circumferential direction. The sleeve33and the intermediate member37thus undergo relative movement in the circumferential direction. Similarly, when the torque around the propeller axis Ap is applied to the second damper38, the second damper38deforms elastically in the circumferential direction, and the inner circumferential portion of the second damper38and the outer circumferential portion of the second damper38undergo relative movement in the circumferential direction. The intermediate member37and the inner cylinder28thus undergo relative movement in the circumferential direction.

As shown inFIG. 2, the front spacer32surrounds the tapered portion25of the propeller shaft7around the propeller axis Ap. A front end of the front spacer32is disposed farther to the front than the tapered portion25and a rear end of the front spacer32is disposed farther to the rear than the tapered portion25. The front spacer32includes a tapered inner circumferential surface aligned along an outer circumferential surface of the tapered portion25. The outer circumferential surface of the tapered portion25contacts the inner circumferential surface of the front spacer32. Forward movement of the front spacer32with respect to the propeller shaft7is restricted by the contact of the outer circumferential surface of the tapered portion25and the inner circumferential surface of the front spacer32.

As shown inFIG. 2, the front spacer32includes a cylindrical fitting portion47fitted inside the front end portion of the inner cylinder28and an annular front pressed portion48disposed farther to the front than the inner cylinder28. The front pressed portion48has a disk shape that is coaxial to the fitting portion47and has a larger outer diameter than the fitting portion47. The outer diameter of the front pressed portion48is greater than the outer diameter of the sleeve33. A rear end surface of the front pressed portion48faces a front end surface of the inner cylinder28in the front/rear direction and an outer circumferential surface of the fitting portion47faces the inner circumferential surface of the inner cylinder28in the radial direction. The fitting portion47and the front pressed portion48define a step that houses the front end portion of the inner cylinder28.

When the propeller shaft7and the propeller8rotate in the forward rotation direction, the front pressed portion48is pressed forward by the inner cylinder28and a thrust in the forward drive direction is transmitted from the propeller member22to the front spacer32. The forward drive direction thrust transmitted to the front spacer32is transmitted from the front spacer32to the tapered portion25and is further transmitted from the propeller shaft7to the lower case12. The forward drive direction thrust is thus transmitted from the outboard motor3to the hull H1via the bracket2and the hull H1is propelled forward.

As shown inFIG. 2, the intermediate spacer34surrounds the small diameter portion26of the propeller shaft7around the propeller axis Ap. The intermediate spacer34includes a disk-shaped main body49surrounding the propeller shaft7around the propeller axis Ap and two sub projections50extending radially outward from an outer circumferential surface of the main body49. The main body49is disposed behind the sleeve33. The two sub projections50are disposed farther radially outward than the sleeve33. In regard to the front/rear direction, the two sub projections50are disposed between the rear end of the intermediate member37and the rear spacer35. As shown inFIG. 5, the two sub projections50are disposed at an interval in the circumferential direction.

As shown inFIG. 5, the main body49is disposed inside a rear end portion of the intermediate member37and the two sub projections50are respectively disposed inside two sub notches51provided in the rear end portion of the intermediate member37. Each sub notch51extends forward from a rear end of the intermediate member37and opens rearward. Each sub notch51is defined by a pair of inner surfaces disposed at an interval in the circumferential direction and a bottom surface connecting front ends of the pair of inner surfaces to each other. A width (length in the circumferential direction) of each sub projection50is shorter than a width of each sub notch51, and in the free state, centers of the sub projections50in the circumferential direction are matched with centers of the sub notches51in the circumferential direction. A pair of side surfaces of each sub projection50thus face the pair of inner surfaces of a sub notch51at intervals in the circumferential direction.

As shown inFIG. 2, the intermediate spacer34is sandwiched by the sleeve33and the rear spacer35in the front/rear direction. The intermediate spacer34thus rotates around the propeller axis Ap together with the sleeve33and the rear spacer35. On the other hand, the intermediate spacer34is not sandwiched by the intermediate member37and the rear spacer35in the front/rear direction. Therefore, in a state in which the side surfaces of the sub projections50are not in contact with the inner surfaces of the sub notches51, the intermediate spacer34and the intermediate member37can undergo relative rotation in the circumferential direction. As shown inFIG. 5, when the intermediate spacer34and the intermediate member37undergo relative rotation around the propeller axis Ap and side surfaces of the sub projections50contact inner surfaces of the sub notches51, the relative rotation of the intermediate spacer34and the intermediate member37in one rotation direction is restricted.

As shown inFIG. 2, the rear spacer35surrounds the small diameter portion26of the propeller shaft7around the propeller axis Ap. The rear spacer35includes a disk-shaped main body52surrounding the propeller shaft7around the propeller axis Ap and two main projections53extending radially outward from an outer circumferential surface of the main body52. An inner circumferential portion of the main body52is spline-connected to the outer circumferential portion of the small-diameter portion26. The main body52is disposed behind the rear end of the intermediate member37and the intermediate spacer34. An outer diameter of the main body52is greater than an outer diameter of the rear end of the intermediate member37. The two main projections53are disposed farther radially outward than the rear end of the intermediate member37. As shown inFIG. 6, the two main projections53are disposed at an interval in the circumferential direction.

As shown inFIG. 6, the main body52is disposed inside the rear end portion of the inner cylinder28and the two main projections53are respectively disposed inside two main notches54provided in the rear end portion of the inner cylinder28. Each main notch54extends forward from a rear end of the inner cylinder28and opens rearward. Each main notch54is defined by a pair of inner surfaces disposed at an interval in the circumferential direction and a bottom surface connecting front ends of the pair of inner surfaces to each other. A width (length in the circumferential direction) of each main projection53is shorter than a width of each main notch54, and in the free state, centers of the main projections53in the circumferential direction are matched with centers of the main notches54in the circumferential direction. A pair of side surfaces of each main projection53thus face the pair of side surfaces of a main notch54at intervals in the circumferential direction.

As shown inFIG. 2, the rear spacer35is sandwiched by the intermediate spacer34and the washer W1in the front/rear direction. The rear spacer35thus rotates around the propeller axis Ap together with the intermediate spacer34and the washer W1. On the other hand, the rear spacer35is not pressed by the inner cylinder28and the intermediate member37. Therefore, in a state in which the side surfaces of the main projections53are not in contact with the side surfaces of the main notches54, the rear spacer35and the inner cylinder28can undergo relative rotation in the circumferential direction. As shown inFIG. 6, when the rear spacer35and the inner cylinder28undergo relative rotation around the propeller axis Ap and side surfaces of the main projections53contact inner surfaces of the main notches54, the relative rotation of the rear spacer35and the inner cylinder28in one rotation direction is restricted. A central angle θ1(angle around the propeller axis Ap; seeFIG. 5) between a side surface of a sub projection50and an inner surface of a sub notch51may be smaller than or may be equal to a central angle θ2(angle around the propeller axis Ap; seeFIG. 6) between a side surface of a main projection53and an inner surface of a main notch54.

As shown inFIG. 2, the rear spacer35includes, in addition to the main body52and the main projections53, a rear pressed portion55that faces the inner cylinder28in the front/rear direction. The rear pressed portion55is a portion that faces the rear end portion of the inner cylinder28in the front/rear direction. InFIG. 2, an example where the rear pressed portion55includes a portion of the main body52and a portion of a main projection53is shown. When the propeller shaft7and the propeller8rotate in a reverse rotation direction, the rear pressed portion55is pressed rearward by the inner cylinder28and a thrust in a reverse drive direction is transmitted from the propeller member22to the rear spacer35. The reverse drive direction thrust transmitted to the rear spacer35is transmitted from the rear spacer35to the propeller shaft7via the washer W1and the nut N1and is further transmitted from the propeller shaft7to the lower case12. The reverse drive direction thrust is thus transmitted from the outboard motor3to the hull H1via the bracket2and the hull H1is propelled in reverse.

FIG. 7is a graph of a relationship of an elastic deformation amount (operating angle) of the damper unit23in the circumferential direction and a magnitude of the torque applied to the damper unit23.

The torque around the propeller axis Ap that is transmitted from the engine4side to the propeller shaft7is transmitted to the propeller member22via the damper unit23. On the other hand, in a case in which a torque around the propeller axis Ap is applied to the propeller member22due to collision of a blade31of the propeller22with a rock or other underwater obstacle, the torque around the propeller axis Ap is transmitted via the damper unit23to the propeller shaft7.

When the torque around the propeller axis Ap is applied to the first damper36, the first damper36twists elastically in the circumferential direction. Therefore, as indicated by thick line arrows inFIG. 5, the sleeve33and the intermediate member37that are coupled to the first damper36undergo relative movement in the circumferential direction and one side surface of each sub projection50approaches the inner surface of the sub notch51that faces the side surface. When the torque around the propeller axis Ap applied to the first damper36reaches a first torque, the side surfaces of the sub projections50contact the inner surfaces of the sub notches51. Also, when the torque around the propeller axis Ap applied to the first damper36falls below the first torque, a twist amount (elastic deformation amount) of the first damper36decreases and the side surfaces of the sub projections50separate from the inner surfaces of the sub notches51.

Similarly, when the torque around the propeller axis Ap is applied to the second damper38, the second damper38twists elastically in the circumferential direction. Therefore, as indicated by thick line arrows inFIG. 6, the intermediate member37and the inner cylinder28that are coupled to the second damper38undergo relative movement in the circumferential direction and one side surface of each main projection53approaches the inner surface of the main notch54that faces the side surface. When the torque around the propeller axis Ap applied to the second damper38reaches a second torque, the side surfaces of the main projections53contact the inner surfaces of the main notches54. Also, when the torque around the propeller axis Ap applied to the second damper38falls below the second torque, a twist amount (elastic deformation amount) of the second damper38decreases and the side surfaces of the main projections53separate from the inner surfaces of the main notches54.

The intermediate spacer34rotates around the propeller axis Ap together with the propeller shaft7. When side surfaces of the sub projections50contact inner surfaces of the sub notches51provided in the intermediate member37, the propeller shaft7and the intermediate member37become coupled by the intermediate spacer34that can be regarded as a rigid body and the torque transmitted to the propeller shaft7is thus transmitted to the intermediate member37without involving the first damper36. Similarly, the rear spacer35rotates around the propeller axis Ap together with the propeller shaft7. When side surfaces of the main projections53contact inner surfaces of the main notches54provided in the inner cylinder28, the propeller shaft7and the inner cylinder28become coupled by the rear spacer35that can be regarded as a rigid body and the torque transmitted to the propeller shaft7is thus transmitted to the inner cylinder28without involving the second damper38.

The first torque by which side surfaces of the sub protrusions50contact inner surfaces of the sub notches51may be less than or may be equal to the second torque by which side surfaces of the main projection53contact inner surfaces of the main notch54. A case in which the first torque and the second torque are equal to a maximum torque (torque corresponding to a maximum operating angle) of the damper unit23is illustrated inFIG. 7. As shown inFIG. 7, in this case, both the first damper36and the second damper38deform elastically in the circumferential direction and an operating angle of the entire damper unit23increases until the torque applied to the propeller shaft7reaches the maximum torque. When the torque applied to the propeller shaft7increases to not less than the maximum torque, the increases of the elastic deformation amounts of the first damper36and the second damper38are restricted by the rear spacer35as a main stopper and the intermediate spacer34as a sub stopper and the operating angle of the damper unit23is maintained fixed.

When the torque applied to the propeller shaft7is less than the maximum torque, the torque transmitted to the propeller shaft7is transmitted from the propeller shaft7to the propeller member22via the first damper36and the second damper38. On the other hand, when the torque applied to the propeller shaft7is not less than the maximum torque, the torque transmitted to the propeller shaft7is transmitted from the propeller shaft7to the propeller member22without involving the first damper36and the second damper38. Similarly, in a case in which a torque is applied to the propeller member22due to collision with an underwater obstacle, the transmission path of the torque is switched according to the magnitude of the torque applied to the propeller member22.

As described above, with the first preferred embodiment, the first damper36and the second damper38are disposed in series on the transmission path transmitting the rotation of the engine4to the plurality of blades31. The torque around the propeller axis Ap transmitted to the propeller shaft7as the input member is transmitted to the inner cylinder28of the propeller member22as the output member via the first damper36, the intermediate member37, and the second damper38, in that order. Oppositely, the torque around the propeller axis Ap transmitted to the inner cylinder28is transmitted to the propeller shaft7via the second damper38, the intermediate member37, and the first damper36, in that order.

The first damper36and the second damper38are disposed in series and therefore, torques of substantially equal magnitudes are applied to the first damper36and the second damper38and the first damper36and the second damper38deform elastically in the circumferential direction (direction around the propeller axis Ap). The maximum operating angle of the damper unit23is a sum of a maximum operating angle of the first damper36and a maximum operating angle of the second damper38. Therefore, with the vessel propulsion apparatus1, the maximum operating angle of the damper unit23can be increased while maintaining the maximum torque (torque corresponding to the maximum operating angle) at not less than a fixed value.

Further, a portion of the second damper38is disposed on the straight line L1passing through the first damper36and is parallel or substantially parallel to the propeller axis Ap and therefore, the portion of the second damper38and the first damper36are aligned in the axial direction (direction along the propeller axis Ap). The damper unit23can thus have a smaller outer diameter than in a case in which the first damper36and the second damper38are disposed concentrically. Therefore, even in a case in which the engine4is an internal combustion engine and the damper unit23is disposed in the interior of the propeller8that defines the exhaust passage20, any reduction of an area of the exhaust passage20can be minimized. As a result, lowering of an output of the vessel propulsion apparatus1can be minimized.

Second Preferred Embodiment

FIG. 8is a sectional view of the propeller shaft7and a propeller208according to a second preferred embodiment of the present invention. A free state in which a torque is not applied to a damper unit223is illustrated inFIG. 8. In the following, the damper unit223in the free state shall be described unless noted otherwise. Also, inFIG. 8, component portions equivalent to respective portions shown inFIG. 1toFIG. 7described above shall be provided with the same reference symbols as inFIG. 1, etc., and description thereof shall be omitted.

The propeller208according to the second preferred embodiment includes a cylindrical propeller member222that generates a thrust and the cylindrical damper unit223that is detachably mounted on the propeller member222. The propeller208is detachably mounted on the rear end portion of the propeller shaft7by the washer W1and the nut N1.

In addition to the inner cylinder28, the outer cylinder29, the plurality of ribs30, and the plurality of blades31, the propeller member222includes a disk-shaped rear flange256provided at a rear end portion of the inner cylinder28. The rear flange256is coaxial to the inner cylinder28and projects radially inward from the inner circumferential surface of the inner cylinder28. In regard to the front/rear direction, the rear flange256is disposed between the second damper38and the rear spacer35. The rear flange256is continuous across an entire circumference and surrounds a rear end portion of a sleeve233around the propeller axis Ap. A rear end surface of the rear flange256faces a front end surface of the rear spacer35.

The damper unit223is disposed on the propeller axis Ap. The damper unit223is housed inside the outer cylinder29of the propeller member222. With the exception of the sleeve and the intermediate member, the damper unit223preferably has the same arrangement as the damper unit23according to the first preferred embodiment. Specifically, the damper unit223includes, in place of the sleeve33and the intermediate member37according to the first preferred embodiment, the cylindrical sleeve233mounted on the propeller shaft7, and a cylindrical intermediate member237arranged to transmit a torque from the first damper36to the downstream side. Further, the damper unit223includes an outer sleeve257arranged to rotate around the propeller axis Ap together with the front spacer32, and an inner sleeve258arranged to rotate around the propeller axis Ap together with the inner cylinder28.

The sleeve233is disposed inside the inner cylinder28. A front end of the sleeve233is disposed farther to the rear than the front end of the inner cylinder28and a rear end of the sleeve233is disposed farther to the front than the rear end of the inner cylinder28. The sleeve233surrounds the small diameter portion26of the propeller shaft7around the propeller axis Ap. The sleeve233is disposed between the front spacer32and the rear spacer35. An outer diameter of the sleeve233is smaller than the outer diameters of the front spacer32and the rear spacer35. The sleeve233is sandwiched in the front/rear direction by the front spacer32and the rear spacer35. The sleeve233thus rotates around the propeller axis Ap together with the propeller shaft7even though the sleeve233is not spline-connected to the propeller shaft7.

The outer sleeve257and the inner sleeve258are disposed inside the inner cylinder28. The outer sleeve257is disposed farther to the front than the inner sleeve258. A front end of the outer sleeve257is disposed farther to the rear than the front end of the inner cylinder28and a rear end of the inner sleeve258is disposed farther to the front than the rear end of the inner cylinder28. The outer sleeve257surrounds the first damper36around the propeller axis Ap, and the inner sleeve258is surrounded by the second damper38around the propeller axis Ap. An inner diameter of the outer sleeve257is greater than an outer diameter of the inner sleeve258. An inner diameter of the inner sleeve258is greater than an outer diameter of the sleeve233. The inner sleeve258surrounds the sleeve233at a radial interval. In regard to the front/rear direction, the outer sleeve257and the inner sleeve258are disposed between the front spacer32and the rear spacer35.

The outer sleeve257includes an uneven front end surface provided with a plurality of claws259projecting forward. The plurality of claws259are aligned at intervals in the circumferential direction. The plurality of claws259are respectively disposed inside a plurality of grooves provided in the fitting portion47of the front spacer32. The plurality of grooves are aligned at intervals in the circumferential direction and are recessed forward from a rear end surface of the front spacer32. The plurality of claws259are thus engaged with the front spacer32from the rear. A torque around the propeller axis Ap is transmitted between the front spacer32and the outer sleeve257by contact of side surfaces of the claws259with inner surfaces of the grooves. The outer sleeve257and the front spacer32thus rotate integrally around the propeller axis Ap. The outer sleeve257thus rotates around the propeller axis Ap together with the propeller shaft7.

The inner sleeve258includes an uneven rear end surface provided with a plurality of claws260that project rearward. The plurality of claws260are aligned at intervals in the circumferential direction. The plurality of claws260are respectively disposed inside a plurality of grooves provided in an inner circumferential portion of the rear flange256. The plurality of grooves are aligned at intervals in the circumferential direction and penetrate through the rear flange256in the front/rear direction. The plurality of claws260are engaged with the rear flange256from the front. The torque around the propeller axis Ap is transmitted between the rear flange256and the inner sleeve258by contact of side surfaces of the claws260with inner surfaces of the grooves. The inner cylinder28and the inner sleeve258thus rotate integrally around the propeller axis Ap.

The intermediate member237includes an inner circumferential surface and outer circumferential surface that are step-shaped and change in diameter in a stepwise manner. The intermediate member237includes an upstream cylindrical portion239coupled to the first damper36, an annular step portion240defining a step at an intermediate portion of the intermediate member237, and a downstream cylindrical portion241coupled to the second damper38.

The upstream cylindrical portion239is surrounded by the first damper36and the downstream cylindrical portion241surrounds the second damper38. The upstream cylindrical portion239and the downstream cylindrical portion241extend in the front/rear direction along the propeller axis Ap. The upstream cylindrical portion239is disposed farther to the front than the downstream cylindrical portion241. The step portion240extends from a rear end of the upstream cylindrical portion239to a front end of the downstream cylindrical portion241. An outer diameter of the upstream cylindrical portion239is smaller than an inner diameter of the downstream cylindrical portion241. An inner diameter of the upstream cylindrical portion239is greater than the outer diameter of the sleeve233. The upstream cylindrical portion239surrounds the sleeve233at a radial interval.

The upstream cylindrical portion239is disposed farther to the front than the second damper38. The downstream cylindrical portion241is disposed farther to the rear than the first damper36. The step portion240defines the step interposed between the first damper36and the second damper38. The rear end surface of the first damper36and the front end surface of the second damper38face the step portion240. The first damper36and the second damper38are aligned in the front/rear direction via the step portion240. A portion of the second damper38is disposed on the straight line L1passing through the first damper36and is parallel or substantially parallel to the propeller axis Ap.

The outer sleeve257is disposed in front of the downstream cylindrical portion241and the inner sleeve258is disposed behind the upstream cylindrical portion239. A rear end portion of the outer sleeve257and a front end portion of the inner sleeve258face the step portion240at intervals in the front/rear direction. The outer sleeve257is disposed between the front spacer32and the intermediate member237, and the inner sleeve258is disposed between the intermediate member237and the rear spacer35. The intermediate member237is rotatable around the propeller axis Ap with respect to the outer sleeve257and the inner sleeve258. Further, the intermediate member237is rotatable around the propeller axis Ap with respect to the inner cylinder28and the sleeve233.

The inner circumferential portion of the first damper36is coupled by a tooth and groove engagement to an outer circumferential portion of the upstream cylindrical portion239, and the outer circumferential portion of the first damper36is coupled by adhesion to an inner circumferential portion of the outer sleeve257. Similarly, the inner circumferential portion of the second damper38is coupled by adhesion to an outer circumferential portion of the inner sleeve258and the outer circumferential portion of the second damper38is coupled by a tooth and groove engagement to an inner circumferential portion of the downstream cylindrical portion241. The first damper36may be coupled by adhesion to the upstream cylindrical portion239and coupled by a tooth and groove engagement to the outer sleeve257. The same applies to the second damper38.

The upstream cylindrical portion239includes an uneven outer circumferential surface provided with the plurality of radially projecting teeth43. The first damper36includes an uneven inner circumferential surface provided with the plurality of radially recessed grooves44. The plurality of teeth43are respectively disposed inside the plurality of grooves44. The inner circumferential surface of the first damper36is in close contact with the outer circumferential surface of the upstream cylindrical portion239in a state in which the plurality of teeth43are engaged with the first damper36. The outer circumferential surface of the upstream cylindrical portion239is tapered toward the front end of the upstream cylindrical portion239. The first damper36is thus restricted in rearward movement by an inclination of the outer circumferential surface of the upstream cylindrical portion239.

The downstream cylindrical portion241includes an uneven inner circumferential surface provided with the plurality of radially projecting teeth43. The second damper38includes the uneven outer circumferential surface provided with the plurality of radially recessed grooves44. The plurality of teeth43are respectively disposed inside the plurality of grooves44. The outer circumferential surface of the second damper38is in close contact with the inner circumferential surface of the downstream cylindrical portion241in a state in which the plurality of teeth43are engaged with the second damper38. The inner circumferential surface of the downstream cylindrical portion241is tapered toward the front end of the downstream cylindrical portion241. The second damper38is thus restricted in forward movement by an inclination of the inner circumferential surface of the downstream cylindrical portion241.

The inner circumferential portion of the first damper36rotates around the propeller axis Ap together with the intermediate member237, and the outer circumferential portion of the first damper36rotates around the propeller axis Ap together with the outer sleeve257. The inner circumferential portion of the second damper38rotates around the propeller axis Ap together with the inner sleeve258and the outer circumferential portion of the second damper38rotates around the propeller axis Ap together with the intermediate member237. When the torque around the propeller axis Ap is applied to the first damper36, the first damper36deforms elastically in the circumferential direction and the inner circumferential portion of the first damper36and the outer circumferential portion of the first damper36undergo relative movement in the circumferential direction. The outer sleeve257and the intermediate member237thus undergo relative movement in the circumferential direction. Similarly, when the torque around the propeller axis Ap is applied to the second damper38, the second damper38deforms elastically in the circumferential direction and the inner circumferential portion of the second damper38and the outer circumferential portion of the second damper38undergo relative movement in the circumferential direction. The intermediate member237and the inner sleeve258thus undergo relative movement in the circumferential direction.

When the torque applied to the propeller shaft7is less than a maximum torque (torque corresponding to a maximum operating angle) of the damper unit223, the torque transmitted to the propeller shaft7is transmitted from the front spacer32to the outer sleeve257and transmitted further from the outer sleeve257to the first damper36. The torque transmitted to the first damper36is transmitted from the intermediate member237to the second damper38and further transmitted from the second damper38to the inner sleeve258. The torque transmitted to the inner sleeve258is transmitted to the inner cylinder28of the propeller member222. The torque around the propeller axis Ap is thus transmitted from the propeller shaft7to the propeller member222via the damper unit223.

Third Preferred Embodiment

FIG. 9is a sectional view of the propeller shaft7and a propeller308according to a third preferred embodiment of the present invention. A free state in which a torque is not applied to a damper unit323is illustrated inFIG. 9. In the following, the damper unit323in the free state shall be described unless noted otherwise. Also, inFIG. 9, component portions equivalent to respective portions shown inFIG. 1toFIG. 8described above shall be provided with the same reference symbols as inFIG. 1, etc., and description thereof shall be omitted.

The propeller308according to the third preferred embodiment includes the propeller member22according to the first preferred embodiment and the cylindrical damper unit323that is detachably mounted on the propeller member22. The propeller308is detachably mounted on the rear end portion of the propeller shaft7by the washer W1and the nut N1.

The damper unit323is disposed on the propeller axis Ap. The damper unit323is housed inside the outer cylinder29of the propeller member22. With the exception of the sleeve and the intermediate member, the damper unit323preferably has the same arrangement as the damper unit23according to the first preferred embodiment. Specifically, the damper unit323includes, in place of the sleeve33according to the first preferred embodiment, the sleeve233according to the second preferred embodiment. Further, the damper unit323includes, in place of the intermediate member37according to the first preferred embodiment, a cylindrical intermediate member337transmitting a torque from the first damper36to the downstream side. Further, the damper unit323includes the outer sleeve257according to the second preferred embodiment.

The intermediate member337surrounds the sleeve233. The intermediate member337is rotatable around the propeller axis Ap with respect to the sleeve233. The intermediate member337includes a step-shaped outer circumferential surface that changes in diameter in a stepwise manner. The intermediate member337includes the upstream cylindrical portion239according to the second preferred embodiment and the downstream cylindrical portion41according to the first preferred embodiment. The first damper36surrounds the upstream cylindrical portion239and the second damper38surrounds the downstream cylindrical portion41. The first damper36is disposed between the upstream cylindrical portion239and the outer sleeve257and the second damper38is disposed between the downstream cylindrical portion41and the inner cylinder28. The upstream cylindrical portion239is disposed in front of the downstream cylindrical portion41. The rear end portion of the upstream cylindrical portion239and the front end portion of the downstream cylindrical portion41are coupled by a tooth and groove engagement. The upstream cylindrical portion239and the downstream cylindrical portion41thus rotate integrally around the propeller axis Ap.

The inner circumferential portion of the first damper36is coupled by a tooth and groove engagement to the outer circumferential portion of the upstream cylindrical portion239, and the outer circumferential portion of the first damper36is coupled by adhesion to the inner circumferential portion of the outer sleeve257. Similarly, the inner circumferential portion of the second damper38is coupled by adhesion to the outer circumferential portion of the downstream cylindrical portion41and the outer circumferential portion of the second damper38is coupled by a tooth and groove engagement to the inner circumferential portion of the inner cylinder28. The first damper36may be coupled by adhesion to the upstream cylindrical portion239and coupled by a tooth and groove engagement to the outer sleeve257. The same applies to the second damper38.

The upstream cylindrical portion239includes the uneven outer circumferential surface provided with the plurality of radially projecting teeth43. The first damper36includes the uneven inner circumferential surface provided with the plurality of radially recessed grooves44. The plurality of teeth43are respectively disposed inside the plurality of grooves44. The inner circumferential surface of the first damper36is in close contact with the outer circumferential surface of the upstream cylindrical portion239in a state in which the plurality of teeth43are engaged with the first damper36. The outer circumferential surface of the upstream cylindrical portion239is tapered toward the front end of the upstream cylindrical portion239. The first damper36is thus restricted in rearward movement by the inclination of the outer circumferential surface of the upstream cylindrical portion239.

The inner cylinder28includes the uneven inner circumferential surface provided with the plurality of radially projecting teeth43. The second damper38includes the uneven outer circumferential surface provided with the plurality of radially recessed grooves44. The plurality of teeth43are respectively disposed inside the plurality of grooves44. The outer circumferential surface of the second damper38is in close contact with the inner circumferential surface of the inner cylinder28in a state in which the plurality of teeth43are engaged with the second damper38. The inner circumferential surface of the rear portion of the inner cylinder28is tapered toward the rear end of the inner cylinder28. The second damper38is thus restricted in rearward movement by the inclination of the inner circumferential surface of the inner cylinder28.

When a torque around the propeller axis Ap is applied to the first damper36, the first damper36deforms elastically in the circumferential direction and the inner circumferential portion of the first damper36and the outer circumferential portion of the first damper36undergo relative movement in the circumferential direction. The outer sleeve257and the intermediate member337thus undergo relative movement in the circumferential direction. Similarly, when the torque around the propeller axis Ap is applied to the second damper38, the second damper38deforms elastically in the circumferential direction and the inner circumferential portion of the second damper38and the outer circumferential portion of the second damper38undergo relative movement in the circumferential direction. The intermediate member337and the inner cylinder28thus undergo relative movement in the circumferential direction.

When the torque applied to the propeller shaft7is less than a maximum torque (torque corresponding to a maximum operating angle) of the damper unit323, the torque transmitted to the propeller shaft7is transmitted from the front spacer32to the outer sleeve257and transmitted further from the outer sleeve257to the first damper36. The torque transmitted to the first damper36is transmitted from the intermediate member337to the second damper38. The torque transmitted to the second damper38is transmitted to the inner cylinder28of the propeller member22. The torque around the propeller axis Ap is thus transmitted from the propeller shaft7to the propeller member22via the damper unit323.

Fourth Preferred Embodiment

FIG. 10is a sectional view of the propeller shaft7and a propeller408according to a fourth preferred embodiment of the present invention. A free state in which a torque is not applied to a damper unit423is illustrated inFIG. 10. In the following, the damper unit423in the free state shall be described unless noted otherwise. Also, inFIG. 10, component portions equivalent to respective portions shown inFIG. 1toFIG. 9described above shall be provided with the same reference symbols as inFIG. 1, etc., and description thereof shall be omitted.

The propeller408according to the fourth preferred embodiment includes the propeller member222according to the second preferred embodiment and the cylindrical damper unit423that is detachably mounted on the propeller member222. The propeller408is detachably mounted on the rear end portion of the propeller shaft7by the washer W1and the nut N1.

The damper unit423is disposed on the propeller axis Ap. The damper unit423is housed inside the outer cylinder29of the propeller member222. With the exception of the sleeve, the intermediate spacer, and the intermediate member, the damper unit423preferably has the same arrangement as the damper unit23according to the first preferred embodiment. Specifically, the damper unit423includes, in place of the sleeve33and the intermediate spacer34according to the first preferred embodiment, a sleeve433and an intermediate spacer434that are cylindrical and are mounted on the propeller shaft7. Further, the damper unit423includes, in place of the intermediate member37according to the first preferred embodiment, a cylindrical intermediate member437transmitting a torque from the first damper36to the downstream side. Further, the damper unit423includes the inner sleeve258according to the second preferred embodiment.

The sleeve433and the intermediate spacer434are disposed inside the inner cylinder28. The sleeve433and the intermediate spacer434extend in the front/rear direction along the propeller axis Ap. The sleeve433is disposed behind the front spacer32and the intermediate spacer434is disposed behind the sleeve433. A front end of the sleeve433is disposed farther to the rear than the front end of the inner cylinder28and a rear end of the intermediate spacer434is disposed farther to the front than the rear end of the inner cylinder28. The front end of the sleeve433is in contact with the front spacer32, and a front end of the intermediate spacer434is in contact with the sleeve433. The front end surface of the rear spacer35is in contact with the intermediate spacer434. The front spacer32, the sleeve433, the intermediate spacer434, and the rear spacer35are pressed forward by the washer W1and the nut N1. The front spacer32, the sleeve433, the intermediate spacer434, and the rear spacer35are thus fixed to the propeller shaft7.

The sleeve433is longer in the front/rear direction than the front spacer32and the rear spacer35. The intermediate spacer434is longer in the front/rear direction than the sleeve433. The intermediate spacer433is thus the longest in the front/rear direction among the front spacer32, the sleeve433, the intermediate spacer434, and the rear spacer35. Also, an outer diameter of the sleeve433is smaller than the outer diameters of the front spacer32and the rear spacer35. An outer diameter of the intermediate spacer434is smaller than the outer diameters of the front spacer32, the sleeve433, and the rear spacer35. The intermediate spacer434is thus the smallest in outer diameter among the front spacer32, the sleeve433, the intermediate spacer434, and the rear spacer35.

The sleeve433and the intermediate spacer434surround the small diameter portion26of the propeller shaft7around the propeller axis Ap. The sleeve433is surrounded by the first damper36, and the intermediate spacer434is surrounded by the inner sleeve258. The rear flange256surrounds a rear end portion of the intermediate spacer434. An inner circumferential portion of the sleeve433is spline-connected to the small diameter portion26of the propeller shaft7. Although the intermediate spacer434is not spline-connected to the small diameter portion26, it is sandwiched in the front/rear direction by the sleeve433and the rear spacer35that are spline-connected to the propeller shaft7. Therefore, as with the sleeve433, the intermediate spacer434also rotates together with the propeller shaft7around the propeller axis Ap.

The intermediate member437includes an upstream cylindrical portion439coupled to the first damper36and a downstream cylindrical portion441coupled to the second damper38. The upstream cylindrical portion439surrounds the first damper36and the downstream cylindrical portion441surrounds the second damper38. The upstream cylindrical portion439and the downstream cylindrical portion441extend in the front/rear direction along the propeller axis Ap. The upstream cylindrical portion439is disposed farther to the front than the downstream cylindrical portion441. A front end of the upstream cylindrical portion439is disposed farther to the rear than the front end of the inner cylinder28, and a rear end of the downstream cylindrical portion441is disposed farther to the front than the rear end of the inner cylinder28. The upstream cylindrical portion439and the downstream cylindrical portion441are disposed along the inner circumferential surface of the inner cylinder28. The intermediate member437is rotatable around the propeller axis Ap with respect to the inner cylinder28. An inner circumferential surface and an outer circumferential surface of the upstream cylindrical portion439are tapered toward a rear end of the intermediate member437. Oppositely, an inner circumferential surface and an outer circumferential surface of the downstream cylindrical portion441are tapered toward a front end of the intermediate member437. The intermediate member437thus includes an inner circumferential surface and an outer circumferential surface with hourglass-shaped configurations that are constricted at intermediate portions.

The first damper36and the second damper38face each other at an interval in the front/rear direction. A portion of the second damper38is thus disposed on the straight line L1passing through the first damper36and is parallel or substantially parallel to the propeller axis Ap. The inner circumferential portion of the first damper36is coupled by adhesion to an outer circumferential portion of the sleeve433and the outer circumferential portion of the first damper36is coupled by a tooth and groove engagement to an inner circumferential portion of the upstream cylindrical portion439. Similarly, the inner circumferential portion of the second damper38is coupled by adhesion to the outer circumferential portion of the inner sleeve258and the outer circumferential portion of the second damper38is coupled by a tooth and groove engagement to an inner circumferential portion of the downstream cylindrical portion441. The first damper36may be coupled by a tooth and groove engagement to the sleeve433and coupled by adhesion to the upstream cylindrical portion439. The same applies to the second damper38.

The upstream cylindrical portion439includes an uneven inner circumferential surface provided with the plurality of radially projecting teeth43. The first damper36includes the uneven outer circumferential surface provided with the plurality of radially recessed grooves44. The plurality of teeth43are respectively disposed inside the plurality of grooves44. The outer circumferential surface of the first damper36is in close contact with the inner circumferential surface of the upstream cylindrical portion439in a state in which the plurality of teeth43are engaged with the first damper36. The inner circumferential surface of the upstream cylindrical portion439is tapered toward the rear end of the upstream cylindrical portion439. The first damper36is thus restricted in rearward movement by an inclination of the outer circumferential surface of the upstream cylindrical portion439.

The downstream cylindrical portion441includes an uneven inner circumferential surface provided with the plurality of radially projecting teeth43. The second damper38includes the uneven outer circumferential surface provided with the plurality of radially recessed grooves44. The plurality of teeth43are respectively disposed inside the plurality of grooves44. The outer circumferential surface of the second damper38is in close contact with the inner circumferential surface of the downstream cylindrical portion441in a state in which the plurality of teeth43are engaged with the second damper38. The inner circumferential surface of the downstream cylindrical portion441is tapered toward the front end of the downstream cylindrical portion441. The second damper38is thus restricted in forward movement by an inclination of the inner circumferential surface of the downstream cylindrical portion441.

When a torque around the propeller axis Ap is applied to the first damper36, the first damper36deforms elastically in the circumferential direction and the inner circumferential portion of the first damper36and the outer circumferential portion of the first damper36undergo relative movement in the circumferential direction. The sleeve433and the intermediate member437thus undergo relative movement in the circumferential direction. Similarly, when the torque around the propeller axis Ap is applied to the second damper38, the second damper38deforms elastically in the circumferential direction and the inner circumferential portion of the second damper38and the outer circumferential portion of the second damper38undergo relative movement in the circumferential direction. The intermediate member437and the inner sleeve258thus undergo relative movement in the circumferential direction.

When the torque applied to the propeller shaft7is less than a maximum torque (torque corresponding to a maximum operating angle) of the damper unit423, the torque transmitted to the propeller shaft7is transmitted from the sleeve433to the first damper36. The torque transmitted to the first damper36is transmitted from the intermediate member437to the second damper38. The torque transmitted to the second damper38is transmitted from the inner sleeve258to the inner cylinder28of the propeller member222. The torque around the propeller axis Ap is thus transmitted from the propeller shaft7to the propeller member222via the damper unit423.

Fifth Preferred Embodiment

FIG. 11is a sectional view of the propeller shaft7and a propeller508according to a fifth preferred embodiment of the present invention. A free state in which a torque is not applied to a damper unit523is illustrated inFIG. 11. In the following, the damper unit523in the free state shall be described unless noted otherwise. Also, inFIG. 11, component portions equivalent to respective portions shown inFIG. 1toFIG. 10described above shall be provided with the same reference symbols as inFIG. 1, etc., and description thereof shall be omitted.

The propeller508according to the fifth preferred embodiment includes a cylindrical propeller member522generating thrust and the cylindrical damper unit523that is detachably mounted on the propeller member522. The propeller508is detachably mounted on the rear end portion of the propeller shaft7by the washer W1and the nut N1.

With the exception of the inner cylinder, the propeller member522preferably has the same arrangement as the propeller member22according to the first preferred embodiment. That is, the propeller member522includes, in place of the inner cylinder28according to the first preferred embodiment, an inner cylinder528surrounding the damper unit523around the propeller axis Ap. The inner cylinder528includes a cylindrical portion560extending in the front/rear direction along the propeller axis Ap and a disk-shaped front flange561provided at a front end portion of the cylindrical portion560. The cylindrical portion560and the front flange561are housed inside the outer cylinder29.

The cylindrical portion560surrounds the damper unit523around the propeller axis Ap. The damper unit523projects rearward from a rear end portion of the cylindrical portion560. A front end of the cylindrical portion560is disposed farther to the rear than the front end of the outer cylinder29and a rear end of the cylindrical portion560is disposed farther to the front than the rear end of the outer cylinder29. Each rib30extends from an outer circumferential surface of the cylindrical portion560to the inner circumferential surface of the outer cylinder29. The inner cylinder528, the outer cylinder29, the ribs30, and the blades31rotate integrally around the propeller axis Ap.

The front flange561is coaxial to the cylindrical portion560and extends radially inward from a front end portion of the cylindrical portion560. The front flange561is continuous across an entire circumference and surrounds the fitted portion47of the front spacer32around the propeller axis Ap. A front end surface of the front flange561faces a rear end surface of the front pressed portion48. When the propeller shaft7and the propeller508are rotated in the forward rotation direction, the front pressed portion48is pressed forward by the front flange561and a thrust in the forward drive direction is transmitted from the propeller member522to the front spacer32.

The damper unit523is disposed on the propeller axis Ap. The damper unit523is housed inside the outer cylinder29of the propeller member522. The damper unit523includes the front spacer32, the sleeve33, and a rear spacer535that are cylindrical and are mounted on the propeller shaft7. The front spacer32is mounted on a front end portion of the inner cylinder528. An opening defined by the front end portion of the inner cylinder528is blocked by the propeller shaft7and the front spacer32. The front end portion of the inner cylinder528is supported by the front spacer32. The front end portion of the inner cylinder528is thus supported by the propeller shaft7via the front spacer32.

The damper unit523further includes the cylindrical first damper36transmitting a torque from the sleeve33to the downstream side, a cylindrical intermediate member537transmitting the torque from the first damper36to the downstream side, and a second damper38transmitting the torque from the intermediate member537to the propeller member522. The damper unit523further includes a main stopper562which causes the propeller shaft7, as the input member, and the inner cylinder523, as the output member, to rotate integrally, when the torque transmitted to the damper unit523is not less than the second torque.

The first damper36, the intermediate member537, and the second damper38surround the sleeve33around the propeller axis Ap. The first damper36is disposed behind the second damper38. The first damper36is surrounded by the intermediate member537and the second damper38surrounds the intermediate member537. The first damper36is disposed farther to the rear than the inner cylinder528, and the second damper38is disposed inside the inner cylinder528. A front portion of the intermediate member537is disposed inside the inner cylinder528, and a rear portion of the intermediate member537projects rearward from the inner cylinder528. In regard to the front/rear direction, the first damper36, the intermediate member537, and the second damper38are disposed between the front spacer32and the rear spacer535.

The intermediate member537includes an inner circumferential surface and outer circumferential surface that are step-shaped and change in diameter in a stepwise manner. The intermediate member537includes an upstream cylindrical portion539coupled to the first damper36, an annular step portion540defining a step at an intermediate portion of the intermediate member537, and a downstream cylindrical portion541coupled to the second damper38. The upstream cylindrical portion539surrounds the first damper36and the downstream cylindrical portion541is surrounded by the second damper38. The upstream cylindrical portion539and the downstream cylindrical portion541extend in the front/rear direction along the propeller axis Ap. The upstream cylindrical portion539is disposed farther to the rear than the downstream cylindrical portion541. The step portion540extends from a rear end of the downstream cylindrical portion541to a front end of the upstream cylindrical portion539. The upstream cylindrical portion539is disposed farther to the rear than the inner cylinder528, and the downstream cylindrical portion541is disposed inside the inner cylinder528. An inner diameter of the upstream cylindrical portion539is greater than an outer diameter of the downstream cylindrical portion541. An outer diameter of the upstream cylindrical portion539is not more than an outer diameter of the cylindrical portion560. An inner diameter of the downstream cylindrical portion541is greater than the outer diameter of the sleeve33. The downstream cylindrical portion541surrounds the sleeve33at a radial interval.

The first damper36is disposed between the upstream cylindrical portion539and the sleeve33, and the second damper38is disposed between the downstream cylindrical portion541and the inner cylinder528(cylindrical portion560). The upstream cylindrical portion539is disposed farther to the rear than the second damper38, and the downstream cylindrical portion541is disposed farther to the front than the first damper36. The step portion540defines the step interposed between the first damper36and the second damper38. The front end surface of the first damper36and the rear end surface of the second damper38face the step portion540. The first damper36and the second damper38are aligned in the front/rear direction via the step portion540. A portion of the second damper38is disposed on the straight line L1passing through the first damper36and is parallel or substantially parallel to the propeller axis Ap.

The inner circumferential portion of the first damper36is coupled by adhesion to the outer circumferential portion of the sleeve33, and the outer circumferential portion of the first damper36is coupled by a tooth and groove engagement to an inner circumferential portion of the upstream cylindrical portion539. Similarly, the inner circumferential portion of the second damper38is coupled by adhesion to an outer circumferential portion of the downstream cylindrical portion541and the outer circumferential portion of the second damper38is coupled by a tooth and groove engagement to an inner circumferential portion of the inner cylinder528. The first damper36may be coupled by a tooth and groove engagement to the sleeve33and coupled by adhesion to the upstream cylindrical portion539. The same applies to the second damper38.

The upstream cylindrical portion539includes an uneven inner circumferential surface provided with the plurality of radially projecting teeth43. The first damper36includes the uneven outer circumferential surface provided with the plurality of radially recessed grooves44. The plurality of teeth43are respectively disposed inside the plurality of grooves44. The outer circumferential surface of the first damper36is in close contact with the inner circumferential surface of the upstream cylindrical portion539in a state in which the plurality of teeth43are engaged with the first damper36. The inner circumferential surface of the upstream cylindrical portion539is tapered toward the front end of the upstream cylindrical portion539. The first damper36is thus restricted in forward movement by an inclination of the outer circumferential surface of the upstream cylindrical portion539.

The inner cylinder528includes an uneven inner circumferential surface provided with the plurality of radially projecting teeth43. The second damper38includes the uneven outer circumferential surface provided with the plurality of radially recessed grooves44. The plurality of teeth43are respectively disposed inside the plurality of grooves44. The outer circumferential surface of the second damper38is in close contact with the inner circumferential surface of the inner cylinder528in a state in which the plurality of teeth43are engaged with the second damper38. The inner circumferential surface of the inner cylinder528(inner circumferential surface of the cylindrical portion560) is tapered toward the front end of the inner cylinder528. The second damper38is thus restricted in forward movement by an inclination of the inner circumferential surface of the inner cylinder528.

The main stopper562is disposed inside the inner cylinder528. The second damper38and the downstream cylindrical portion541are disposed behind the main stopper562. The main stopper562surrounds the front end portion of the sleeve33around the propeller axis Ap. The main stopper562includes a disk-shaped main body563surrounding the sleeve33around the propeller axis Ap and two main projections553extending radially outward from an outer circumferential surface of the main body563. The two main projections553are disposed farther radially outward than the sleeve33. The two main projections553are disposed at an interval in the circumferential direction.

The main stopper562is disposed inside a recessed portion565defined by the front flange561of the inner cylinder528. The recessed portion565is recessed forward. An inner diameter of the recessed portion565is smaller than an inner diameter of the cylindrical portion560. The two main projections553are respectively disposed inside two main notches554provided in the recessed portion565. The main notches554extend forward from a rear end of the main flange561and open rearward. Each main notch554is defined by a pair of inner surfaces disposed at an interval in the circumferential direction and a bottom surface connecting front ends of the pair of inner surfaces to each other. A width (length in the circumferential direction) of each main projection553is shorter than a width of each main notch554, and in the free state, centers of the main projections553in the circumferential direction are matched with centers of the main notches554in the circumferential direction. A pair of side surfaces of each main projection553thus face the pair of inner surfaces of a main notch554at intervals in the circumferential direction.

An inner circumferential portion of the main stopper562is spline-connected to the outer circumferential portion of the sleeve33. The main stopper562thus rotates around the propeller axis Ap together with the sleeve33and the propeller shaft7. On the other hand, the inner cylinder528can undergo relative rotation with respect to the front spacer32. The inner cylinder528can thus undergo relative rotation with respect to the propeller shaft7. Therefore, in a state in which the side surfaces of the main projections553are not in contact with the inner surfaces of the main notches554, the main stopper562and the inner cylinder528can undergo relative rotation in the circumferential direction. When the main stopper562and the inner cylinder528undergo relative rotation around the propeller axis Ap and side surfaces of the main projections553contact inner surfaces of the main notches554, the relative rotation of the main stopper562and the inner cylinder528in one rotation direction is restricted.

The rear spacer535surrounds the propeller shaft7around the propeller axis Ap. The rear spacer535is mounted on a rear end portion of the upstream cylindrical portion539. An opening defined by a rear end portion of the intermediate member537is blocked by the propeller shaft7and the rear spacer535. The rear spacer535includes a disk-shaped main body552surrounding the propeller shaft7around the propeller axis Ap and two sub projections550extending radially outward from an outer circumferential surface of the main body552. The two sub projections550are disposed at an interval in the circumferential direction.

The main body552is disposed inside a rear end portion of the intermediate member537and the two sub projections550are respectively disposed inside two sub notches551provided in the rear end portion of the intermediate member537. Each sub notch551extends forward from a rear end of the intermediate member537and opens rearward. Each sub notch551is defined by a pair of inner surfaces disposed at an interval in the circumferential direction and a bottom surface connecting front ends of the pair of inner surfaces to each other. A width (length in the circumferential direction) of each sub projection550is shorter than a width of each sub notch551, and in the free state, centers of the sub projection550in the circumferential direction are matched with centers of the sub notches551in the circumferential direction. Opposite side surfaces of each sub projection550thus face the side surfaces of a sub notch551at intervals in the circumferential direction.

The rear spacer535as a sub stopper is sandwiched by the sleeve33and the washer W1in the front/rear direction. The rear spacer535thus rotates around the propeller axis Ap together with the propeller shaft7. On the other hand, the intermediate member537can undergo relative rotation with respect to the propeller shaft7. Therefore, in a state in which the side surfaces of the sub projections550are not in contact with the side surfaces of the sub notches551, the rear spacer535and the intermediate member537can undergo relative rotation in the circumferential direction. When the rear spacer535and the intermediate member537undergo relative rotation around the propeller axis Ap and side surfaces of the sub projections550contact inner surfaces of the sub notches551, the relative rotation of the rear spacer535and the intermediate member537in one rotation direction is restricted. A central angle between a side surface of a main projection553and an inner surface of a main notch554may be smaller than or may be equal to a central angle between a side surface of a sub projection550and an inner surface of a sub notch551.

When the torque applied to the propeller shaft7is less than a maximum torque (torque corresponding to a maximum operating angle) of the damper unit523, the torque transmitted to the propeller shaft7is transmitted from the sleeve33to the first damper36. The torque transmitted to the first damper36is transmitted from the intermediate member537to the second damper38. The torque transmitted to the second damper38is transmitted to the inner cylinder528of the propeller member522. The torque around the propeller axis Ap is thus transmitted from the propeller shaft7to the propeller member522via the damper unit523.

Sixth Preferred Embodiment

FIG. 12is a sectional view of the propeller shaft7and a propeller608according to a sixth preferred embodiment of the present invention. A free state in which a torque is not applied to a damper unit623is illustrated inFIG. 12. In the following, the damper unit623in the free state shall be described unless noted otherwise. Also, inFIG. 12, component portions equivalent to respective portions shown inFIG. 1toFIG. 11described above shall be provided with the same reference symbols as inFIG. 1, etc., and description thereof shall be omitted.

The propeller608according to the sixth preferred embodiment includes the propeller member522according to the fifth preferred embodiment and the cylindrical damper unit623that is detachably mounted on the propeller member522. The propeller608is detachably mounted on the rear end portion of the propeller shaft7by the washer W1and the nut N1.

The damper unit623is disposed on the propeller axis Ap. The damper unit623is housed inside the outer cylinder29of the propeller member522. With the exception of the intermediate member, the damper unit623preferably has the same arrangement as the damper unit523according to the fifth preferred embodiment. That is, the damper unit623includes, in place of the intermediate member537according to the fifth preferred embodiment, a cylindrical intermediate member637transmitting a torque from the first damper36to the downstream side.

The intermediate member637extends in the front/rear direction along the propeller axis Ap. The intermediate member637surrounds the sleeve33around the propeller axis Ap. The intermediate member337includes a conical outer circumferential surface that changes in diameter in a continuous manner and a step-shaped inner circumferential surface that changes in diameter in a stepwise manner. A front end portion of the intermediate member637is disposed inside the inner cylinder528. The intermediate member637projects rearward from the rear end portion of the inner cylinder528. In regard to the front/rear direction, the intermediate member637is disposed between the front spacer32and the rear spacer535.

The main stopper562is disposed in front of the intermediate member637, and the rear spacer535is mounted on a rear end portion of the intermediate member637. An opening defined by the rear end portion of the intermediate member637is blocked by the propeller shaft7and the rear spacer535. The main body552of the rear spacer535is disposed inside the rear end portion of the intermediate member637and the two sub projections550of the rear spacer535are respectively disposed inside the two sub notches551provided in the rear end portion of the intermediate member637.

The intermediate member637includes an upstream cylindrical portion639coupled to the first damper36and a downstream cylindrical portion641coupled to the second damper38. The upstream cylindrical portion639surrounds the first damper36and the downstream cylindrical portion641is surrounded by the second damper38. The upstream cylindrical portion639and the downstream cylindrical portion641extend in the front/rear direction along the propeller axis Ap. The upstream cylindrical portion639is disposed farther to the rear than the downstream cylindrical portion641. The upstream cylindrical portion639is disposed farther to the rear than the inner cylinder528, and the downstream cylindrical portion641is disposed inside the inner cylinder528.

An outer diameter and an inner diameter of the upstream cylindrical portion639increase in a continuous manner as a rear end of the intermediate member637is approached. Similarly, an outer diameter of the downstream cylindrical portion641increases in a continuous manner as the rear end of the intermediate member637is approached. The outer diameter of the upstream cylindrical portion639is greater than the outer diameter of the downstream cylindrical portion641. A maximum outer diameter of the upstream cylindrical portion639is not more than the outer diameter of the cylindrical portion560of the inner cylinder528. An inner diameter of the downstream cylindrical portion641is fixed and is greater than the outer diameter of the sleeve33. The downstream cylindrical portion641surrounds the sleeve33at a radial interval. A thickness (radial distance from an inner circumferential surface to an outer circumferential surface) of the upstream cylindrical portion639is fixed, and a thickness of the downstream cylindrical portion641increases in a continuous manner as the rear end of the intermediate member637is approached.

The first damper36is disposed between the upstream cylindrical portion639and the sleeve33, and the second damper38is disposed between the downstream cylindrical portion641and the inner cylinder528(cylindrical portion560). A rear end portion of the upstream cylindrical portion639is disposed farther to the rear than the second damper38, and a front end portion of the downstream cylindrical portion641is disposed farther to the front than the first damper36. A portion of the second damper38is disposed on the straight line L1passing through the first damper36and is parallel or substantially parallel to the propeller axis Ap.

The inner circumferential portion of the first damper36is coupled by adhesion to the outer circumferential portion of the sleeve33and the outer circumferential portion of the first damper36is coupled by a tooth and groove engagement to an inner circumferential portion of the upstream cylindrical portion639. Similarly, the inner circumferential portion of the second damper38is coupled by adhesion to an outer circumferential portion of the downstream cylindrical portion641and the outer circumferential portion of the second damper38is coupled by a tooth and groove engagement to the inner circumferential portion of the inner cylinder528. The first damper36may be coupled by a tooth and groove engagement to the sleeve33and coupled by adhesion to the upstream cylindrical portion639. The same applies to the second damper38.

The upstream cylindrical portion639includes an uneven inner circumferential surface provided with the plurality of radially projecting teeth43. The first damper36includes the uneven outer circumferential surface provided with the plurality of radially recessed grooves44. The plurality of teeth43are respectively disposed inside the plurality of grooves44. The outer circumferential surface of the first damper36is in close contact with the inner circumferential surface of the upstream cylindrical portion639in a state in which the plurality of teeth43are engaged with the first damper36. The inner circumferential surface of the upstream cylindrical portion639is tapered toward the front end of the upstream cylindrical portion639. The first damper36is thus restricted in forward movement by an inclination of the inner circumferential surface of the upstream cylindrical portion639.

The downstream cylindrical portion641includes an uneven inner circumferential surface provided with the plurality of radially projecting teeth43. The second damper38includes the uneven outer circumferential surface provided with the plurality of radially recessed grooves44. The plurality of teeth43are respectively disposed inside the plurality of grooves44. The outer circumferential surface of the second damper38is in close contact with the inner circumferential surface of the downstream cylindrical portion641in a state in which the plurality of teeth43are engaged with the second damper38. The inner circumferential surface of the downstream cylindrical portion641is tapered toward the front end of the downstream cylindrical portion641. The second damper38is thus restricted in forward movement by an inclination of the inner circumferential surface of the downstream cylindrical portion641.

When a torque applied to the propeller shaft7is less than a maximum torque (torque corresponding to a maximum operating angle) of the damper unit623, the torque transmitted to the propeller shaft7is transmitted from the sleeve33to the first damper36. The torque transmitted to the first damper36is then transmitted from the intermediate member637to the second damper38. The torque transmitted to the second damper38is transmitted to the inner cylinder528of the propeller member522. The torque around the propeller axis Ap is thus transmitted from the propeller shaft7to the propeller member522via the damper unit623.

Seventh Preferred Embodiment

FIG. 13is a sectional view of the propeller shaft7and a propeller708according to a seventh preferred embodiment of the present invention. A free state in which a torque is not applied to a damper unit723is illustrated inFIG. 13. In the following, the damper unit723in the free state shall be described unless noted otherwise. Also, inFIG. 13, component portions equivalent to respective portions shown inFIG. 1toFIG. 12described above shall be provided with the same reference symbols as inFIG. 1, etc., and description thereof shall be omitted.

The propeller708according to the seventh preferred embodiment includes the propeller member522according to the fifth preferred embodiment and the cylindrical damper unit723that is detachably mounted on the propeller member522. The propeller708is detachably mounted on the rear end portion of the propeller shaft7by the washer W1and the nut N1.

The damper unit723is disposed on the propeller axis Ap. The damper unit723is housed inside the outer cylinder29of the propeller member522. In addition to the arrangement of the damper unit523according to the fifth preferred embodiment, the damper unit723further includes a second intermediate member767, transmitting a torque from the second damper38to the downstream side, and a cylindrical third damper768transmitting the torque from the second intermediate member767to the propeller member522.

The intermediate member537(shall hereinafter be referred to as the “first intermediate member537” in regard to the seventh preferred embodiment) transmits the torque between the first damper36as a first upstream damper and the second damper38as a first downstream damper. Also, the second intermediate member767transmits the torque between the second damper38as a second upstream damper and the third damper768as a second downstream damper. The third damper768is made of an elastic material. The elastic moduli of the first damper36, the second damper38, and the third damper768may be equal or may differ.

In regard to the front/rear direction, the second intermediate member767is disposed between the inner cylinder528and the first intermediate member537. The second intermediate member767extends in the front/rear direction along the propeller axis Ap. The second intermediate member767surrounds the sleeve33around the propeller axis Ap. The second intermediate member767includes an outer circumferential surface and inner circumferential surface that are step-shaped and change in diameter in a stepwise manner. The second intermediate member767includes an upstream cylindrical portion769coupled to the second damper38, an annular step portion770defining a step at an intermediate portion of the second intermediate member767, and a downstream cylindrical portion771coupled to the third damper768. The upstream cylindrical portion769surrounds the second damper38and the downstream cylindrical portion771is surrounded by the third damper768.

The upstream cylindrical portion769and the downstream cylindrical portion771extend in the front/rear direction along the propeller axis Ap. The upstream cylindrical portion769is disposed farther to the rear than the downstream cylindrical portion771. The step portion770extends from a rear end of the downstream cylindrical portion771to a front end of the upstream cylindrical portion769. The upstream cylindrical portion769and the step portion770are disposed farther to the rear than the inner cylinder528, and the downstream cylindrical portion771is disposed inside the inner cylinder528. The upstream cylindrical portion769is disposed between the cylindrical portion560of the inner cylinder528and the upstream cylindrical portion539of the first intermediate member537. An inner diameter of the upstream cylindrical portion769is greater than an outer diameter of the downstream cylindrical portion771. An outer diameter of the upstream cylindrical portion769is not more than the outer diameter of the cylindrical portion560. An inner diameter of the downstream cylindrical portion771is greater than the outer diameter of the sleeve33. The downstream cylindrical portion771surrounds the sleeve33at a radial interval.

The second damper38is disposed between the downstream cylindrical portion541of the first intermediate member537and the upstream cylindrical portion769of the second intermediate member767, and the third damper68is disposed between the downstream cylindrical portion771of the second intermediate member767and the cylindrical portion560of the inner cylinder528. The upstream cylindrical portion769of the second intermediate member767is disposed farther to the rear than the third damper768, and the downstream cylindrical portion771of the second intermediate member767is disposed farther to the front than the second damper38. The step portion770of the second intermediate member767defines the step interposed between the second damper38and the third damper768. The front end surface of the second damper38and the rear end surface of the third damper768face the step portion770. The second damper38and the third damper768are aligned in the front/rear direction via the step portion770. A portion of the third damper768is disposed on the straight line L1passing through the first damper36and the second damper38and is parallel or substantially parallel to the propeller axis Ap.

The inner circumferential portion of the second damper38rotates around the propeller axis Ap together with the downstream cylindrical portion541of the first intermediate member537, and the outer circumferential portion of the second damper38rotates around the propeller axis Ap together with the upstream cylindrical portion769of the second intermediate member767. The inner circumferential portion of the second damper38is coupled by adhesion to the outer circumferential portion of the downstream cylindrical portion541of the first intermediate member537, and the outer circumferential portion of the second damper38is coupled by a tooth and groove engagement to an inner circumferential portion of the upstream cylindrical portion769of the second intermediate member767. The second damper38may be coupled by a tooth and groove engagement to the first intermediate member537and coupled by adhesion to the second intermediate member767.

An inner circumferential portion of the third damper768rotates around the propeller axis Ap together with the downstream cylindrical portion771of the second intermediate member767, and an outer circumferential portion of the third damper768rotates around the propeller axis Ap together with the inner circumferential portion of the inner cylinder528. The inner circumferential portion of the third damper768is coupled by adhesion to an outer circumferential portion of the downstream cylindrical portion771of the second intermediate member767, and the outer circumferential portion of the third damper768is coupled by a tooth and groove engagement to the inner circumferential portion of the inner cylinder528. The third damper768may be coupled by a tooth and groove engagement to the second intermediate member767and coupled by adhesion to the inner cylinder528.

The upstream cylindrical portion769of the second intermediate member767includes an uneven inner circumferential surface provided with the plurality of radially projecting teeth43. The second damper38includes the uneven outer circumferential surface provided with the plurality of radially recessed grooves44. The plurality of teeth43are respectively disposed inside the plurality of grooves44. The outer circumferential surface of the second damper38is in close contact with the inner circumferential surface of the upstream cylindrical portion769in a state in which the plurality of teeth43are engaged with the second damper38.

The cylindrical portion560of the inner cylinder528includes an uneven inner circumferential surface provided with the plurality of radially projecting teeth43. The third damper768includes an uneven outer circumferential surface provided with the plurality of radially recessed grooves44. The plurality of teeth43are respectively disposed inside the plurality of grooves44. The outer circumferential surface of the third damper768is in close contact with the inner circumferential surface of the inner cylinder528in a state in which the plurality of teeth43are engaged with the third damper768.

When a torque applied to the propeller shaft7is less than a maximum torque (torque corresponding to a maximum operating angle) of the damper unit723, the torque transmitted to the propeller shaft7is transmitted from the sleeve33to the first damper36. The torque transmitted to the first damper36is then transmitted from the first intermediate member537to the second damper38. The torque transmitted to the second damper38is transmitted from the second intermediate member767to the third damper768. The torque transmitted to the third damper768is transmitted to the inner cylinder528of the propeller member522. The torque around the propeller axis Ap is thus transmitted from the propeller shaft7to the propeller member522via the damper unit723.

Eighth Preferred Embodiment

FIG. 14is a sectional view of a vessel propulsion apparatus801according to an eighth preferred embodiment of the present invention. A free state in which a torque is not applied to a damper unit823is illustrated inFIG. 14. In the following, the damper unit823in the free state shall be described unless noted otherwise. Also, inFIG. 14, component portions equivalent to respective portions shown inFIG. 1toFIG. 13described above shall be provided with the same reference symbols as inFIG. 1, etc., and description thereof shall be omitted.

With the exception of the propeller shaft, the propeller, and the damper unit, the vessel propulsion apparatus801preferably has the same arrangement as the vessel propulsion apparatus1according to the first preferred embodiment. Specifically, the vessel propulsion apparatus801includes, in place of the propeller shaft7according to the first preferred embodiment, a propeller shaft807coupled to the forward/reverse drive switching mechanism6.

The propeller shaft807extends in the front/rear direction inside the lower case12. The propeller shaft807is rotatable around the propeller axis Ap with respect to the casing10. The propeller shaft807penetrates through the cylindrical rear gear16, provided in the forward/reverse drive switching mechanism6, in the front/rear direction. A rear end portion of the propeller shaft807projects rearward from the rear gear16. The rear end portion of the propeller shaft807is disposed inside the lower case12.

The propeller shaft807includes a columnar small diameter portion872extending in the front/rear direction along the propeller axis Ap and a large diameter portion873disposed behind the small diameter portion872. The small diameter portion872is supported by the rear gear16via a roller bearing B1disposed inside the rear gear16. The large diameter portion873is disposed behind the rear gear16. The large diameter portion873is coaxial to the small diameter portion872. The large diameter portion873is thicker than the small diameter portion872. An outer diameter of the large diameter portion873is thus greater than an inner diameter of the rear gear16. The large diameter portion873includes a circular columnar recessed portion865that is recessed forward from a rear end surface of the large diameter portion873.

The vessel propulsion apparatus801includes a cylindrical supporting member874supporting the rear end portion of the propeller shaft807, a roller bearing B2supporting the supporting member874in a manner enabling rotation around the propeller axis Ap, and a ball bearing B3supporting a rear end portion of the rear gear16in a manner enabling rotation around the propeller axis Ap. Further, the vessel propulsion apparatus801includes a cylindrical bearing housing875housing the supporting member874, the roller bearing B2, and the ball bearing B3.

The bearing housing875is disposed inside the lower case12. The supporting member874, the roller bearing B2, and the ball bearing B3are thus also disposed inside the lower case12. The bearing housing875has a cylindrical shape extending in the front/rear direction along the propeller axis Ap. An interior of the bearing housing875is filled with oil, which is an example of a lubricant. The bearing housing875is held by the lower case12.

Inside the bearing housing875, the supporting member874surrounds the rear end portion of the propeller shaft807around the propeller axis Ap. The supporting member874extends in the front/rear direction along the propeller axis Ap. A front end portion of the supporting member874is disposed farther to the rear than the rear gear16and the roller bearing B2, and a rear end portion of the supporting member874is disposed farther to the rear than the propeller shaft807. The rear end portion of the supporting member874is supported from the rear by a step provided on an inner circumferential surface of the bearing housing875. Inside the bearing housing875, the roller bearing B2surrounds the supporting member874around the propeller axis Ap. The roller bearing B2and the supporting member874are disposed behind the ball bearing B3.

The supporting member874is supported by the roller bearing B2in a manner enabling rotation around the propeller axis Ap. The roller bearing B2is supported by the bearing housing875. The supporting member874is thus held by the bearing housing875via the roller bearing B2. The large diameter portion873of the propeller shaft807is fitted inside the supporting member874. Inside the front end portion of the supporting member874, the large diameter portion873is restricted in forward movement by a front ring876that surrounds the propeller shaft807. An inner circumferential portion of the supporting member874is spline-connected to an outer circumferential portion of the large diameter portion873. The supporting member874thus rotates around the propeller axis Ap together with the propeller shaft807.

In place of the propeller8and the damper unit23according to the first preferred embodiment, the vessel propulsion apparatus801includes a damper unit823coupled to the propeller shaft807and a propeller808coupled to the propeller shaft807via the damper unit823. The damper unit823is disposed on a transmission path transmitting the rotation of the engine4(seeFIG. 1) to the plurality of blades31of the propeller808. The rotation of the engine4is thus transmitted to the propeller808via the damper unit823.

The propeller808includes a cylindrical propeller member822that generates a thrust. The propeller member822includes an inner cylinder828surrounding the damper unit823around the propeller axis Ap, the outer cylinder29surrounding the inner cylinder828coaxially at a radial interval, the plurality of ribs30coupling the inner cylinder828and the outer cylinder29at the plurality of positions that are separated in the circumferential direction, and the plurality of blades31extending outward from the outer cylinder29. The inner cylinder828includes a cylindrical portion860extending in the front/rear direction along the propeller axis Ap and the disk-shaped front flange561provided at a front end portion of the cylindrical portion860. The propeller808is detachably mounted on the damper unit823by the washer W1and the nut N1.

The damper unit823is disposed on the propeller axis Ap. A portion of the damper unit823is housed inside the lower case12, and a remaining portion of the damper unit823is housed inside the propeller808. The damper unit823includes an intermediate member837extending rearward along the propeller axis Ap from the rear end portion of the propeller shaft807. The intermediate member837may be a single integral member or may include a plurality of members integrally coupled. A case in which the intermediate member837includes the plurality of members is illustrated inFIG. 14. The intermediate member837includes an intermediate shaft877and the sleeve33that rotate integrally around the propeller axis Ap. The intermediate shaft877extends rearward along the propeller axis Ap from the rear end portion of the propeller shaft807.

The intermediate shaft877includes the large diameter portion24, the tapered portion25, the small diameter portion26, and the bolt portion27that are columnar and extend in the front/rear direction along the propeller axis Ap. The large diameter portion24, the tapered portion25, the small diameter portion26, and the bolt portion27are aligned in that order in the front/rear direction from the front. The large diameter portion24is thicker than the small diameter portion26and the small diameter portion26is thicker than the bolt portion27. The tapered portion25extends from the rear end of the large diameter portion24to the front end of the small diameter portion26and is tapered toward the small diameter portion26. The intermediate shaft877extends in the front/rear direction inside the lower case12and projects rearward from the lower case12. The large diameter portion24is disposed inside the lower case12, and the tapered portion25, the small diameter portion26, and the bolt portion27are disposed inside the propeller808.

The large diameter portion24of the intermediate shaft877is disposed inside the bearing housing875. The large diameter portion24of the intermediate shaft877is inserted inside the supporting member874. The large diameter portion24of the intermediate shaft877extends rearward from the supporting member874. A front end portion of the intermediate shaft877(large diameter portion24) is fitted inside the circular columnar recessed portion865provided in the rear end portion (large diameter portion873) of the propeller shaft807. The front end portion of the intermediate shaft877is supported in the front/rear direction by the rear end portion of the propeller shaft807via the roller bearing B3and a plate878that are disposed between a bottom surface of the recessed portion865and a front end surface of the intermediate shaft877. Further, the front end portion of the intermediate shaft877is radially supported by the rear end portion of the propeller shaft807via the roller bearing B3disposed along an inner circumferential surface of the recessed portion865. The propeller shaft807and the intermediate shaft877can undergo relative rotation around the propeller axis Ap.

The damper unit823includes the cylindrical first damper36transmitting a torque between the supporting member874and the intermediate shaft877. The first damper36is disposed in the interior of the supporting member874that is filled with the oil. The first damper36is thus disposed inside the lower case12. The first damper36surrounds the intermediate shaft877around the propeller axis Ap. The first damper36is disposed between an inner circumferential surface of the supporting member874and an outer circumferential surface of the intermediate shaft877. The first damper36extends in the front/rear direction along the propeller axis Ap. The rear end of the first damper36is disposed farther to the front than a rear end of the supporting member874.

The inner circumferential portion of the first damper36is coupled by adhesion to an outer circumferential portion of the intermediate shaft877and the outer circumferential portion of the first damper36is coupled by a tooth and groove engagement to an inner circumferential portion of the supporting member874. The inner circumferential portion of the first damper36rotates around the propeller axis Ap together with the intermediate shaft877, and the outer circumferential portion of the first damper36rotates around the propeller axis Ap together with the supporting member874. The first damper36may be coupled by a tooth and groove engagement to the intermediate shaft877and coupled by adhesion to the supporting member874.

The supporting member874includes an uneven inner circumferential surface provided with the plurality of radially projecting teeth43. The first damper36includes the uneven outer circumferential surface provided with the plurality of radially recessed grooves44. The plurality of teeth43are respectively disposed inside the plurality of grooves44. The outer circumferential surface of the first damper36is in close contact with the inner circumferential surface of the supporting member874in a state in which the plurality of teeth43are engaged with the first damper36. The first damper36is restricted in rearward movement by a rear ring879surrounding the intermediate shaft877inside the rear end portion of the supporting member874.

The damper unit823includes the cylindrical front spacer32and rear spacer35that are mounted on the intermediate shaft877. The front spacer32is disposed in front of the sleeve33and the rear spacer35is disposed behind the sleeve33. The front spacer32, the sleeve33, and the rear spacer35are thus aligned in that order in the front/rear direction from the front. The front spacer32, the sleeve33, and the rear spacer35surround the intermediate shaft877around the propeller axis Ap. The front spacer32is mounted on a front end portion of the inner cylinder828and the rear spacer85is mounted on a rear end portion of the inner cylinder828. The sleeve33is disposed inside the inner cylinder828.

Forward movement of the front spacer32with respect to the intermediate shaft877is restricted by contact of the outer circumferential surface of the tapered portion25and the inner circumferential surface of the front spacer32. The inner circumferential portion of the sleeve33and the inner circumferential portion of the rear spacer35are spline-connected to the small diameter portion26of the intermediate shaft877. The front spacer32, the sleeve33, and the rear spacer35are fixed to the intermediate shaft877by the washer W1and the nut N1mounted on the bolt portion27of the intermediate shaft877. The intermediate shaft877, the front spacer32, the sleeve33, and the rear spacer35thus rotate integrally around the propeller axis Ap.

The damper unit823includes the second damper38that transmits a torque between the sleeve33and the inner cylinder828. The second damper38is disposed between the outer circumferential surface of the sleeve33and an inner circumferential surface of the inner cylinder828. The second damper38is thus disposed in an interior of the inner cylinder828that is disposed underwater. The second damper38surrounds the sleeve33around the propeller axis Ap. The second damper38extends in the front/rear direction. The front end portion of the second damper38surrounds the front end portion of the sleeve33, and the rear end portion of the second damper38is disposed farther to the front than the rear end portion of the sleeve33. In regard to the front/rear direction, the second damper38is disposed between the front spacer32and the rear spacer35. The rear spacer35faces the second damper38at an interval in the front/rear direction. A portion of the second damper38is positioned on the straight line L1passing through the first damper36and is parallel or substantially parallel to the propeller axis Ap.

The inner circumferential portion of the second damper38is coupled by adhesion to the outer circumferential portion of the sleeve33and the outer circumferential portion of the second damper38is coupled by a tooth and groove engagement to an inner circumferential portion of the inner cylinder828. The inner circumferential portion of the second damper38rotates around the propeller axis Ap together with the sleeve33, and the outer circumferential portion of the second damper38rotates around the propeller axis Ap together with the inner cylinder828. The second damper38may be coupled by a tooth and groove engagement to the sleeve33and coupled by adhesion to the inner cylinder828.

The inner cylinder828includes an uneven inner circumferential surface provided with the plurality of radially projecting teeth43. The second damper38includes the uneven outer circumferential surface provided with the plurality of radially recessed grooves44. The plurality of teeth43are respectively disposed inside the plurality of grooves44. The outer circumferential surface of the second damper38is in close contact with the inner circumferential surface of the inner cylinder828in a state in which the plurality of teeth43are engaged with the second damper38. The inner circumferential surface of the inner cylinder828is tapered toward the front end of the inner cylinder828. The second damper38is thus restricted in forward movement by an inclination of the inner circumferential surface of the inner cylinder828.

When a torque applied to the propeller shaft807is less than a maximum torque (torque corresponding to a maximum operating angle) of the damper unit823, the torque transmitted to the propeller shaft807is transmitted from the supporting member874to the first damper36. The torque transmitted to the first damper36is transmitted from the intermediate shaft877to the sleeve33and transmitted further from the sleeve33to the second damper38. The torque transmitted to the second damper38is transmitted to the inner cylinder828of the propeller member822. The torque around the propeller axis Ap is thus transmitted from the propeller shaft807to the propeller member822via the damper unit823.

Ninth Preferred Embodiment

FIG. 15is a sectional view of a portion of a vessel propulsion apparatus901according to a ninth preferred embodiment of the present invention. A free state in which a torque is not applied to a damper unit923is illustrated inFIG. 15. In the following, the damper unit923in the free state shall be described unless noted otherwise. Also, inFIG. 15, component portions equivalent to respective portions shown inFIG. 1toFIG. 14described above shall be provided with the same reference symbols as inFIG. 1, etc., and description thereof shall be omitted.

In addition to the arrangement of the vessel propulsion apparatus1according to the first preferred embodiment, the vessel propulsion apparatus901includes a damper unit923disposed on a transmission path transmitting the rotation of the engine4(seeFIG. 1) to the plurality of blades31(seeFIG. 1) of the propeller8. The damper unit923is housed inside the casing10. The damper unit923is disposed on the drive axis Ad. The damper unit923is disposed higher than the water pump WP (seeFIG. 1) disposed on the drive axis Ad. The damper unit923may be disposed lower than the water pump WP.

The driveshaft5includes a plurality of shafts (a first shaft979, a second shaft980, and a third shaft981) extending in the up/down direction along the drive axis Ad. The first shaft979is disposed above the second shaft980, and the second shaft980is disposed above the third shaft981. The first shaft979is thus disposed farther to the upstream side than the second shaft980on the transmission path, and the second shaft980is disposed farther to the upstream side than the third shaft981on the transmission path.

The second shaft980includes a cylindrical upper portion982defining an upper recessed portion that is opened upward, cylindrical lower portion983defining a lower recessed portion that is opened downward, and a disk-shaped partition portion984partitioning the upper recessed portion and the lower recessed portion. The upper portion982and the lower portion983have cylindrical shapes extending in the up/down direction. An outer diameter and an inner diameter of the upper portion982are greater than an outer diameter and an inner diameter of the lower portion983. A lower end portion of the first shaft979is inserted inside the upper portion982, and an upper end portion of the third shaft981is inserted inside the lower portion983. The lower end portion of the first shaft979and the upper end portion of the third shaft981face each other in the up/down direction via the partition portion984. The first shaft979is coupled via the damper unit923to the second shaft980and an outer circumferential portion of the third shaft981is spline-connected to an inner circumferential portion of the lower portion983. The second shaft980and the third shaft981can thus undergo relative movement in the up/down direction and rotate integrally around the drive axis Ad.

The damper unit923transmits a torque around the drive axis Ad between the first shaft979as an input member and the second shaft980as an output member and absorbs a vibration around the drive axis Ad between the first shaft979and the second shaft980. The damper unit923includes the cylindrical sleeve33and the main stopper562that are mounted on the first shaft979. Further, the damper unit923includes the cylindrical first damper36transmitting the torque from the sleeve33to the downstream side, a cylindrical intermediate member937transmitting the torque from the first damper36to the downstream side, and the cylindrical second damper38transmitting the torque from the intermediate member937to the second shaft980.

The sleeve33and the main stopper562extend in the up/down direction along the drive axis Ad. The sleeve33and the main stopper562are aligned in that order in the up/down direction from above. The sleeve33is longer in the up/down direction than the main stopper562. The outer diameter of the sleeve33is smaller than the outer diameter of the main stopper562. The sleeve33and the main stopper562are disposed inside the second shaft980. The sleeve33projects upward from an upper end portion of the second shaft980. The sleeve33and the main stopper562surround the first shaft979around the drive axis Ad. The inner circumferential portions of the sleeve33and the main stopper562are spline-connected to an outer circumferential portion of the first shaft979. The sleeve33and the main stopper562are thus movable in the up/down direction with respect to the first shaft979and rotate around the drive axis Ad together with the first shaft979.

The main stopper562is disposed inside a recessed portion965defined by the partition portion984. The recessed portion965is recessed downward. The main stopper562includes the disk-shaped main body563surrounding a lower end portion of the first shaft979around the drive axis Ad and the two main projections553extending radially outward from the outer circumferential surface of the main body563. The two main projections553are disposed farther radially outward than the lower end of the sleeve33. The two main projections553are disposed at an interval in the circumferential direction (direction around the drive axis Ad).

The main body563is disposed inside the recessed portion965of the partition portion984, and the two main projections553are respectively disposed inside the two main notches554provided in the recessed portion965. The main notches554extend downward from an upper end of the partition portion984and open upward. Each main notch554is defined by the pair of inner surfaces disposed at an interval in the circumferential direction and the bottom surface connecting lower ends of the pair of inner surfaces to each other. The width (length in the circumferential direction) of each main projection553is shorter than the width of each main notch554, and in the free state, the centers of the main projections553in the circumferential direction are matched with the centers of the main notches554in the circumferential direction. The pair of side surfaces of each main projection553thus face the pair of inner surfaces of a main notch554at intervals in the circumferential direction.

The inner circumferential portion of the main stopper562is spline-connected to an outer circumferential portion of the first shaft979. The main stopper562thus rotates around the drive axis Ad together with the first shaft. On the other hand, the second shaft980can undergo relative rotation around the drive axis Ad with respect to the first shaft979. Therefore, in a state in which the side surfaces of the main projections553are not in contact with the inner surfaces of the main notches554, the main stopper562and the second shaft980can undergo relative rotation in the circumferential direction. When the main stopper562and the second shaft980undergo relative rotation around the drive axis Ad and side surfaces of the main projections553contact inner surfaces of the main notches554, the relative rotation of the main stopper562and the second shaft980in one rotation direction is restricted. The first shaft979and the second shaft980are thus coupled together by the main stopper562and rotate integrally around the drive axis Ad.

The intermediate member937includes an inner circumferential surface and outer circumferential surface that are step-shaped and change in diameter in a stepwise manner. The intermediate member937includes an upstream cylindrical portion939coupled to the first damper36, an annular step portion940defining a step at an intermediate portion of the intermediate member937, and a downstream cylindrical portion941coupled to the second damper38.

The upstream cylindrical portion939surrounds the first damper36and the downstream cylindrical portion941is surrounded by the second damper38. The upstream cylindrical portion939and the downstream cylindrical portion941extend in the up/down direction along the drive axis Ad. The upstream cylindrical portion939is disposed higher than the downstream cylindrical portion941. The step portion940extends from a lower end of the upstream cylindrical portion939to an upper end of the downstream cylindrical portion941. An inner diameter of the upstream cylindrical portion939is greater than an outer diameter of the downstream cylindrical portion941. An inner diameter of the downstream cylindrical portion941is greater than the outer diameter of the sleeve33. The downstream cylindrical portion941surrounds the sleeve33across a radial interval (in directions orthogonal or substantially orthogonal to the drive axis Ad).

The upstream cylindrical portion939is disposed higher than the second damper38. The downstream cylindrical portion941is disposed lower than the first damper36. The step portion940defines the step interposed between the first damper36and the second damper38. The lower end surface of the first damper36and the upper end surface of the second damper38face the step portion940. The first damper36and the second damper38are aligned in the up/down direction via the step portion940. A portion of the second damper38is disposed on the straight line L1passing through the first damper36and is parallel or substantially parallel to the drive axis Ad.

The first damper36is disposed between the outer circumferential surface of the sleeve33and an inner circumferential surface of the upstream cylindrical portion939. The inner circumferential portion of the first damper36is coupled by adhesion to the outer circumferential portion of the sleeve33, and the outer circumferential portion of the first damper36is coupled by a tooth and groove engagement to the inner circumferential portion of the upstream cylindrical portion939. Similarly, the second damper38is disposed between an outer circumferential surface of the downstream cylindrical portion941and an inner circumferential surface of the second shaft980. The inner circumferential portion of the second damper38is coupled by adhesion to the outer circumferential surface of the downstream cylindrical portion941and the outer circumferential portion of the second damper38is coupled by a tooth and groove engagement to the inner circumferential portion of the second shaft980. The first damper36may be coupled by a tooth and groove engagement to the sleeve33and coupled by adhesion to the upstream cylindrical portion939. The same applies to the second damper38.

The upstream cylindrical portion939includes an uneven inner circumferential surface provided with the plurality of radially projecting teeth43. The first damper36includes the uneven outer circumferential surface provided with the plurality of radially recessed grooves44. The plurality of teeth43are respectively disposed inside the plurality of grooves44. The outer circumferential surface of the first damper36is in close contact with the inner circumferential surface of the upstream cylindrical portion939in a state in which the plurality of teeth43are engaged with the first damper36. The inner circumferential surface of the upstream cylindrical portion939is tapered toward the lower end of the upstream cylindrical portion939. The first damper36is thus restricted in downward movement by an inclination of the outer circumferential surface of the upstream cylindrical portion939.

The upper portion982of the second shaft980includes an uneven inner circumferential surface provided with the plurality of radially projecting teeth43. The second damper38includes the uneven outer circumferential surface provided with the plurality of radially recessed grooves44. The plurality of teeth43are respectively disposed inside the plurality of grooves44. The outer circumferential surface of the second damper38is in close contact with the inner circumferential surface of the second shaft980in a state in which the plurality of teeth43are engaged with the second damper38. The inner circumferential surface of the second shaft980becomes narrower as the front end of the second shaft980is approached. The second damper38is thus restricted in downward movement by an inclination of the inner circumferential surface of the second shaft980.

When the torque applied to the first shaft979of the driveshaft5is less than a maximum torque (torque corresponding to a maximum operating angle) of the damper unit923, the torque transmitted to the first shaft979is transmitted from the sleeve33to the first damper36. The torque transmitted to the first damper36is then transmitted from the intermediate member937to the second damper38. The torque transmitted to the second damper38is transmitted from the second shaft980to the third shaft981. The torque transmitted to the third shaft981is then transmitted to the propeller8via the forward/reverse drive switching mechanism6and the propeller shaft7. The torque around the drive axis Ad is thus transmitted from the first shaft979as the input member to the second shaft980as the output member via the damper unit923.

Other Preferred Embodiments

Although the first to ninth preferred embodiments of the present invention have been described above, the present invention is not restricted to the contents of the first to ninth preferred embodiments and various modifications are possible within the scope of the claims.

For example, with the first preferred embodiment, a case in which the first damper is preferably coupled to the propeller shaft via the sleeve that is detachably mounted on the propeller shaft was described. However, the first damper may be coupled directly to the propeller shaft. Similarly, with each of the second to ninth preferred embodiments, the first damper may be coupled directly to any of the propeller shaft, the intermediate shaft, and the driveshaft without involvement of the sleeve.

Also, with each of the first and fifth to seventh preferred embodiments, a case in which the damper unit is preferably provided with both the main stopper and the sub stopper was described. However, the sub stopper may be omitted and the damper unit may be provided with just the main stopper.

Also, with each of the second to fourth, eighth, and ninth preferred embodiments, a case in which the damper unit is preferably provided with only the main stopper was described. However, the damper unit may be provided with both the main stopper and the sub stopper.

Also, with the first and fifth to seventh preferred embodiments, a case in which the main stopper preferably causes the input member (propeller shaft) and the output member (inner cylinder of the propeller member) to rotate integrally, and the sub stopper causes the input member and the intermediate member to rotate integrally was described. However, the sub stopper may cause the output member and the intermediate member to rotate integrally. Also, the main stopper may cause the input member and the intermediate member to rotate integrally and the sub stopper may cause the output member and the intermediate member to rotate integrally.

Also, with each of the first to seventh preferred embodiments, a case in which the damper unit preferably is disposed on the propeller axis and the entire damper unit is housed inside the propeller member was described. Also, with the eighth preferred embodiment, a case in which the damper unit is disposed on the propeller axis, a portion of the damper unit is housed inside the casing of the vessel propulsion apparatus, and the remaining portion of the damper unit is disposed inside the propeller was described. However, the damper unit may be disposed on the propeller axis and the entire damper unit may be housed inside the casing. For example, the damper unit may be disposed inside a frame X1of alternate long and short dashed line shown inFIG. 1.

Also, with each of the first to ninth preferred embodiments, a case in which the vessel propulsion apparatus preferably is an outboard motor was described. However, the vessel propulsion apparatus may be a propulsion system other than an outboard motor. For example, the vessel propulsion apparatus may be an inboard/outboard motor. Similarly, with each of the first to ninth preferred embodiments, a case in which the propeller including the damper unit preferably is used in the outboard motor was described. However, the propeller including the damper unit may be used in an inboard/outboard motor or other propulsion system besides the outboard motor.

The present application corresponds to Japanese Patent Application No. 2012-160977 filed on Jul. 19, 2012 in the Japan Patent Office, the entire disclosure of which is incorporated herein by reference.