Marine propulsion system supported by a strut

Patent metadata

Field	Value
Publication number	US-10906618-B2
Application number	US-201816176521-A
Country	US
Kind code	B2
Filing date	Oct 31, 2018
Priority date	Oct 31, 2018
Publication date	Feb 2, 2021
Grant date	Feb 2, 2021

Abstract

A marine propulsion system, supported by a strut, comprising an inner propeller shaft supporting a first propeller adjacent a trailing end thereof, and the inner propeller shaft is connected to the drive shaft for receiving and supplying a first portion of torque to the first propeller as well as transfer thrust, generated by the first propeller, along the inner propeller shaft back to the drive shaft. An outer propeller shaft supports a second propeller adjacent a trailing and thereof, and the outer propeller shaft surrounds the inner propeller shaft. A differential gear set receives a second portion of the torque and supplies the second portion to the outer propeller shaft so that the second propeller rotates in an opposite rotational direction to the first propeller. The thrust, generated by the first and the second propellers, is conveyed along either the inner or the outer propeller shafts, to the drive shaft.

First claim

Wherefore, we claim:

1. A marine propulsion system, supported by a strut, comprising:
an inner propeller shaft supporting a first propeller adjacent a trailing end thereof, and the inner propeller shaft having an interface, at a leading end thereof, to facilitate connection with a drive shaft for receiving torque supplied thereto and for supplying a first portion of the torque to the first propeller;
an outer propeller shaft defining an axis and supporting a second propeller adjacent a trailing end thereof, and the outer propeller shaft surrounding at least a portion of the inner propeller shaft; and
a differential gear set is axially arranged between a leading end of the outer propeller shaft and the trailing end of the outer propeller shaft, the differential gear set receiving a second portion of the torque from the drive shaft and supplying the second portion of torque to the outer propeller shaft so that the second propeller rotates in an opposite direction to the first propeller;
wherein thrust, generated by rotation of the first and the second propellers, is conveyed back along either the inner propeller shaft or the outer propeller shaft and back to the drive shaft while the thrust, conveyed upstream to the drive shaft, avoids from passing through either the differential gear set or the strut.

2. The marine propulsion system according to claim 1 , wherein the marine propulsion system is incorporated into a vessel which includes a transmission and an engine, the engine is drivingly connected to the transmission, and the transmission is drivingly connected to a leading end of the drive shaft to transfer torque thereto, and
a rudder is located behind the first and the second propellers to facilitate steering of the vessel by an operator.

3. A marine propulsion system comprising:
a strut having a strut through bore extending therethrough;
an inner propeller shaft supporting a first propeller adjacent a trailing end thereof, and the inner propeller shaft having an interface, at a leading end thereof, to facilitate connection with a drive shaft for receiving torque therefrom and supplying a first portion of the torque to the first propeller as well as for transferring thrust, generated by the first propeller, along the inner propeller shaft back to the drive shaft;
an outer propeller shaft supporting a second propeller adjacent a trailing end thereof, and the outer propeller shaft surrounding a portion of the inner propeller shaft;
the inner and the outer propeller shafts both extending completely through the strut through bore;
a differential gear set being accommodated within the strut and surrounding both the outer and inner propeller shafts, the differential gear set comprising a differential input shaft, a differential output shaft and first and second idle gears, and the differential input shaft being drivingly connected to the inner propeller shaft in order to receive a second portion of the torque supplied thereto and the differential gear set reversing the second portion of the torque so that the differential output shaft drives the outer propeller shaft so as to rotate the second propeller in an opposite rotational direction than the first propeller; and
a leading end of the outer propeller shaft being connected to a leading end of the inner propeller shaft to facilitate, during operation, both rotation of the outer propeller shaft with respect to the inner propeller shaft as well as transfer of thrust, generated by the second propeller, to the inner propeller shaft and back to the drive shaft.

4. The marine propulsion system according to claim 3 , wherein the strut is fixedly secured to a bottom surface of a hull of a vessel by a mounting plate and a plurality of fasteners such that, following installation of the strut, the hull is sandwiched between the mounting plate and an end face of the strut.

5. The marine propulsion system according to claim 4 , wherein at least one contoured spacer insert/shim is located between the bottom surface of the hull and the end face of the strut to modify an orientation/position of the strut, relative to at least one of the hull or the drive shaft, and assist with aligning the drive shaft with at least the inner and outer propeller shafts so that thrust, generated by the first and second propellers, is transferred and conveyed back along the inner and outer propeller shafts to the drive shaft.

6. The marine propulsion system according to claim 3 , wherein the strut through bore extends completely through a central region of the strut, from a leading end to a trailing end thereof, and the strut through bore is sized so as to receive and accommodate components of the marine propulsion system therein.

7. The marine propulsion system according to claim 3 , wherein a trailing end of the strut through bore carries an internal thread while a leading end of a through bore extension carries an external thread, and an exterior surface of the through bore extension carries a pair of spaced apart O-rings which engage with an inwardly facing surface of the strut through bore to form a watertight seal therebetween and prevent water from flowing therebetween.

8. The marine propulsion system according to claim 3 , wherein the strut also includes a strut blind bore which extends from the end face of the strut toward a skeg, and the strut blind bore passes through the strut through bore and terminates prior to reaching an end portion of the skeg.

9. The marine propulsion system according to claim 3 , wherein a spline, on a trailing end of the drive shaft, matingly engages with a spline of the inner propeller shaft to form a spline connection which couples those two shafts with one another while also compensating for any misalignment between at least the drive shaft and the inner propeller shaft.

10. The marine propulsion system according to claim 9 , wherein the trailing end of the drive shaft, adjacent but upstream of the spline connection, has an annular groove which accommodates a mating pair of half rings, and the mating pair of half rings are sandwiched between a chamfered surface, formed in the leading end of the inner propeller shaft, and an inwardly facing chamfer formed in a shaft nut which engages with the inner propeller shaft to retain the spline connection between the drive shaft and the inner propeller shaft and prevent inadvertent separation thereof.

11. The marine propulsion system according to claim 7 , wherein first rotatable fluid tight seal assembly is located between a trailing end of the inner propeller shaft and a trailing end of the outer propeller shaft to prevent water from passing between the inner and the outer propeller shafts;
a first needle bearing is located between the trailing end of the inner propeller shaft and the trailing end of the outer propeller shaft, adjacent to but upstream of the first rotatable fluid tight seal assembly, to facilitate rotation of the inner and the outer propeller shafts relative to one another;
a second rotatable fluid tight seal assembly is located between the outer propeller shaft and the trailing end of the through bore extension to prevent water from passing therebetween; and
a second needle bearing is located between the outer propeller shaft and the trailing end of the through bore extension, adjacent to but upstream of the second rotatable fluid tight seal assembly, to facilitate rotation of the outer propeller shaft relative to the through bore extension.

12. The marine propulsion system according to claim 8 , wherein first and second idler gears, of the differential gear set, are at least partially located within the strut blind bore, the first idler gear is support adjacent one

Assignees

• Zahnradfabrik Friedrichshafen

Inventors

• Stanley Keith
• Orvieto Andrew
• Gruenwald Dave
• Danner Bryan

Classifications

• B63H5/10 Primary

  of coaxial type, e.g. of counter-rotative type · CPC title

• B63H23/34

  Propeller shafts; Paddle-wheel shafts; Attachment of propellers on shafts · CPC title

• B63B3/42

  Shaft brackets · CPC title

• B63H1/14

  Propellers (pitch changing B63H3/00) · CPC title

• B63H2005/103

  of co-rotative type, i.e. rotating in the same direction, e.g. twin propellers · CPC title