Marine propulsion – Screw propeller – Having transmission
Reexamination Certificate
2000-07-10
2002-08-20
Swinehart, Ed (Department: 3617)
Marine propulsion
Screw propeller
Having transmission
Reexamination Certificate
active
06435923
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to the field of watercraft, and more particularly to the field of marine propulsion systems, and specifically to a two speed transmission with forward-reverse gearing for a watercraft wherein the transmission housing forms the gimbal housing of an in-board/out-board drive unit.
In conventional single speed marine drives, an engine is mechanically coupled to a propeller either directly or through a gear box to provide a single gearing ratio. It is known that a single gear ratio connection between the engine and propeller will provide less than optimal performance for many applications. There have been efforts to improve the performance of marine propulsion systems by the use of multi-speed and hydraulically coupled transmissions. It is known that the performance of a watercraft may be improved by providing a higher gear ratio connection between the engine and the propeller for low speed operation and acceleration, and by providing a direct drive or overdrive gear ratio between the engine and the propeller for high speed operation. In this manner, the engine may be operated at a point closer to its peak power output during a wider range of operating conditions.
U.S. Pat. No. 5,711,742 issued on Jan. 27, 1998, to Leinonen, et. al., incorporated by reference herein, describes a multi-speed marine propulsion system with an automatic shifting mechanism. An automatic transmission is interposed between the engine and the in-board/out-board drive apparatus. Although providing improved performance when compared to prior art single speed propulsion systems, the device of Leinonen creates an excessively long drive line which necessitates the placement of the engine in a more forward position within the watercraft hull than may otherwise be desirable.
U.S. Pat. No. 4,820,209 issued on Apr. 11, 1989, to Newman, incorporated by reference herein, describes a marine propulsion system having a fluid coupling with a variable power output. While this system avoids the long drive line of the Leinonen apparatus, it does so at the expense of multi-speed gear ratios. In lieu of multi-speed gears, the device of Newman provides for a controlled slippage between the engine and the propeller in order to improve low speed watercraft operation. The hydraulic coupling and forward-reverse gearing of the Newman transmission are enclosed within a housing passing through the transom of the watercraft, which in turn connects to the vertical drive unit containing the propeller. The device of Newman fails to provide a direct mechanical connection between the engine and the propeller at a plurality of gearing ratios.
BRIEF SUMMARY OF THE INVENTION
Thus, there is a particular need for an improved multi-speed mechanical drive transmission for a watercraft. Accordingly, a transmission for a watercraft is described herein as including: a first housing adapted for attachment to a motor; an input shaft rotatably supported by the first housing; a first housing output gear rotatably supported by the first housing; a forward-reverse shifting apparatus supported in the first housing for selective engagement between the input shaft and the first housing output gear in one of a forward and a reverse directions; a second housing attached to the first housing; an output shaft rotatably supported by the second housing; and a connection between the first housing output gear and the output shaft for providing rotation of the output shaft in response to rotation of the first housing output gear.
One embodiment of such a transmission is disclosed herein as including a housing; a input shaft rotatably supported by the housing; a output shaft rotatably supported by the housing; a first sun gear attached to and concentric with the input shaft for rotation therewith; a ring gear; a first planetary gear engaged between the first sun gear and the ring gear, the first planetary gear having a axis of rotation affixed to a carrier; a forward clutch disposed between the input shaft and the carrier and operable for selective engagement therebetween; a reverse clutch disposed between the housing and the carrier and operable for selective engagement therebetween; a second sun gear; a second planetary gear engaged between the second sun gear and the ring gear, the second planetary gear attached to the output shaft for rotation therewith; a first gear clutch disposed between the sun gear and the housing and operable for selective engagement therebetween; a second gear clutch disposed between the output shaft and the sun gear for selective engagement therebetween.
A marine propulsion apparatus is described herein as having: an engine having an output; a first housing attached to the engine; an input shaft rotatably supported by the first housing; a first sun gear attached to and concentric with the input shaft for rotation therewith; a ring gear; a first planetary gear engaged between the first sun gear and the ring gear, the first planetary gear having a axis of rotation affixed to a carrier; a forward clutch disposed between the input shaft and the carrier and operable for selective engagement therebetween; a reverse clutch disposed between the housing and the carrier and operable for selective engagement therebetween; a second housing adapted for attachment to the first housing; an output shaft rotatably supported by the second housing and operatively connected to the ring gear for rotation therewith; a vertical drive housing attached to the second housing; a drive shaft rotatably supported by the vertical drive housing and attached to the output shaft; and a propeller connected to the drive shaft.
The transmission described herein may be incorporated into a watercraft including: a hull having a transom; an engine disposed within the hull and having an output; a gimbal housing attached to the engine and passing through the transom; a vertical drive housing rotatably attached to the gimbal housing; a transmission comprising a first-second gear shifting apparatus disposed within the gimbal housing, the transmission having an input attached to the engine output and an output; a drive shaft rotatably disposed in the vertical drive housing and having an input end attached to the transmission output and an output end; and a propeller attached to the drive shaft output end.
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MerCruiser's Black Trac Transmission, Jim Barron, Jul. 1998.
Bombardier Motor Corporation of America
Swinehart Ed
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