Marine propulsion – Screw propeller – Propulsion unit casing
Reexamination Certificate
1998-09-11
2001-02-06
Basinger, Sherman (Department: 3617)
Marine propulsion
Screw propeller
Propulsion unit casing
C440S08800J
Reexamination Certificate
active
06183323
ABSTRACT:
TECHNICAL FIELD
The present invention relates to an outboard marine drive including an air cooled internal combustion engine which has a vertical crankshaft carrying a cooling air fan.
BACKGROUND OF THE INVENTION
It is advantageous to use an air-cooled internal combustion engine for a small outboard marine drive in view of reducing weight. Such an engine requires fresh cooling air to be continuously supplied for preventing the overheating of the engine. For aesthetic considerations and convenience of handling, it is desirable to cover the engine. Thus, conflicting requirements are imposed on small outboard marine engines. According to the invention disclosed in Japanese UM publication (kokoku) No. 2-23782, a cover is placed over the cylinder head of an outboard marine engine while the crankcase thereof is exposed. However, the aesthetic considerations are extremely important, and it is desired to minimize the exposure of the internal combustion engine.
BRIEF SUMMARY OF THE INVENTION
In view of such problems of the prior art, a primary object of the present invention is to provide an outboard marine drive using an air-cooled internal combustion engine which is relatively filly covered, but can be favorably air-cooled.
A second object of the present invention is to provide an outboard marine drive using an air-cooled internal combustion engine which is relatively fully covered, and light in weight.
A third object of the present invention is to provide an outboard marine drive using an air-cooled internal combustion engine which is relatively fully covered, and easy to service.
According to the present invention, these and other objects can be accomplished by providing an outboard marine drive having an internal combustion engine incorporated with a vertically oriented crankshaft and a cooling fan attached to an upper end of the crankshaft, comprising: an under case attached to a lower end of the engine, the under case being provided with a substantially cylindrical upright wall located inside an outer periphery of the under case so as to surround a lower part of the engine; an engine cover which is detachably attached to the under cover so as to jointly cover the engine and define a first chamber, the engine cover being provided with an air inlet to introduce cooling air into the first chamber; and a fan cover which jointly covers the engine and defines a second chamber inside the first chamber, the fan cover being provided with an air inlet opposite to the cooling fan, while the under case is provided with an air outlet for expelling cooling air out of the second chamber; wherein a lower peripheral edge of the fan cover abuts an opposing upper peripheral edge of the cylindrical upright wall of the under case.
Thus, the fan cover can cover the engine closely in cooperation with the under case so that a narrow air passage is defined around the engine, and cooling air of high velocity can be continuously passed around the engine. This enhances the cooling effect such that the engine can be substantially entirely covered without risking the possibility of overheating the engine. In particular, by providing the lower peripheral edge of the fan cover with a peripheral groove which receives the opposing upper peripheral edge of the cylindrical upright wall of the under case, it is possible to firmly secure the fan cover relative to the under case which can be firmly attached to a lower part of the engine. Additionally, the opposing edges of the fan cover and the under case may be provided with a plurality of pin and hole engagement arrangements for positioning the fan cover relative to the under case against any lateral movement.
Preferably, the air inlet of the engine cover is provided at an upper rear part of the engine cover, and the inlet of the fan cover is provided in an upper part of the fan cover. Also, the provision of the first chamber defined between the engine cover and the fan cover prevents water which may get into the first chamber from reaching the second chamber. Therefore, the engine can be properly protected from ill effects resulting from the intrusion of water into the first chamber.
Typically, a recoil starter is attached to an upper part of the engine, and may be placed in an upper part of the fan cover in such a manner that the inlet of the fan cover is provided in a cover of the recoil starter. To even further enhance the cooling effect, an air guide plate may be provided inside the second chamber for directing cooling air toward a crankcase of the engine. To minimize the number of component parts and simplify the assembly work, the air guide plate consists of an extension of a gasket interposed between a base end of an exhaust pipe and a corresponding exhaust port of the engine.
REFERENCES:
patent: 4692123 (1987-09-01), Tada et al.
patent: 5884594 (1999-03-01), Wiehle
Ikuma Tomonori
Mizuguchi Hiroshi
Tanaka Mitsuharu
Basinger Sherman
Honda Giken Kogyo Kabushiki Kaisha
MacPherson Alan H.
Michelson Greg J.
Skjerven Morrill & MacPherson LLP
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