Marine propulsion – Screw propeller – Shafting
Reexamination Certificate
1999-11-23
2001-07-24
Morano, S. Joseph (Department: 3617)
Marine propulsion
Screw propeller
Shafting
C440S08800J, C123S090310
Reexamination Certificate
active
06264515
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an outboard motor used to propel a boat. More specifically it relates to a four-stroke engine mounted within an outboard motor.
In general, outboard motors have an engine mounted on a plate-like engine holder. The engine contains a vertically mounted crankshaft which is rotatably connected to the lower end of the crankshaft. The crankshaft extends downward and drives a screw propeller. Four-stroke engines are more prevalent than two-stroke engines in today's outboard motors due to environmental considerations.
In a four-stroke engine, a camshaft drive mechanism transmits the rotation of the crankshaft to a camshaft located above the engine. Camshaft drive mechanisms generally use a belt drive system. A drive pulley is attached to the upper end of the crankshaft which projects from the upper surface of the engine. A driven pulley is connected to the upper end of the camshaft which projects from the upper surface of the engine. A toothed belt is wrapped around the drive pulley and driven pulley.
The engine is lubricated with an oil pump. The oil pump is mounted at the lower surface of the engine. The oil pump is driven by either the crankshaft or camshaft. The oil is drawn up from the oil pan and distributed within the engine providing lubrication. In order to prevent oil leaks, an oil seal housing containing an oil seal is located along the lower surface of the engine where the crankshaft projects downward.
In conventional outboard motors, however, substantial space must be provided above the engine because the camshaft drive mechanism is located along the upper surface of the engine. This makes it difficult to fit anything else above the engine. Additionally, in such a configuration, the length of crankshaft that must be exposed is relatively long in order to accommodate the drive pulley and fly wheel. This inevitably causes rotational vibration.
On the other hand, if the camshaft drive mechanism is located on the lower part of the engine, the height of the engine increases and this raises the center of gravity of the outboard motor. Also, it is necessary to provide a dedicated casing member to accommodate the camshaft drive mechanism along the bottom surface of the engine. This increases the cost and weight of the outboard motor. It is also more difficult to design and layout the outboard motor engine because the oil pump and the oil seal housing must be adjacent to the camshaft drive mechanism.
OBJECTS AND SUMMARY OF THE INVENTION
It is an object of the present invention to overcome the drawbacks and limitations of the prior art.
It is a further object of the present invention to reduce the overall height needed for the outboard motor.
It is yet a further object of the present invention to provide a camshaft drive mechanism, oil pump and oil seal housing along the lower surface of the engine without increasing its cost or weight.
It is yet a further object of the present invention to improve the design and layout of an outboard motor.
It is yet another object of the invention to improve the ability to attach and detach the oil seal housing while maintaining a good oil seal.
It is yet another object of the present invention to simplify the positioning of the oil seal housing when attaching it to the engine.
It is yet another object of the present invention to improve the start-up characteristics of the engine especially after it is tilted upward.
Briefly stated, the present invention provides an outboard motor with an engine where the exposed ends of the crankshaft and camshaft project downward toward the bottom surface of the engine. An accommodation chamber is recessed within the bottom surface of the engine. A chain driven camshaft drive mechanism fits within this accommodation chamber. An oil pump, mounted below the accommodation chamber, is driven by the crankshaft. The bottom end of the crankshaft is sandwiched between the bottom surface of the engine and an oil seal housing. The oil seal housing fits within a recessed opening in a plate-like engine holder positioned below the engine. A plurality of positioning and fastening bosses are used to align and fix the oil seal housing to the engine. When the engine is removed from the outboard motor, its bottom surface is flat enabling the engine sit upright on a workbench.
According to an embodiment of the invention, there is provided an outboard motor comprising: an engine; an accommodation chamber the accommodation chamber being disposed within a bottom portion of the engine; a camshaft drive mechanism; the camshaft drive mechanism being disposed within the accommodation chamber; and means for rotating the camshaft drive mechanism.
According to another embodiment of the invention, there is provided an engine comprising: an engine body; an accommodation chamber; the accommodation chamber being disposed within a bottom portion of the engine body; a camshaft drive mechanism; the camshaft drive mechanism being disposed fully within the accommodation chamber; and means for rotating the camshaft drive mechanism.
The above, and other objects, features and advantages of the present invention will become apparent from the following description read in conjunction with the accompanying drawings, in which like reference numerals designate the same elements.
REFERENCES:
patent: 5171177 (1992-12-01), Hubbell
patent: 6045419 (2000-04-01), Mineno et al.
patent: 10339165 (1998-12-01), None
Pending Application.
Mineno Kazuo
Toyama Takashi
Morano S. Joseph
Morrison Law Firm
Suzuki Motor Corporation
Wright Andrew
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