Marine propulsion – Screw propeller – Propulsion unit casing
Reexamination Certificate
1999-01-15
2001-10-16
Morano, S. Joseph (Department: 3617)
Marine propulsion
Screw propeller
Propulsion unit casing
Reexamination Certificate
active
06302749
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an outboard motor having an alternator belt-driven by a vertical engine received in an engine room covered by an engine cover.
2. Description of the Prior Art
Outboard motors generally have a vertical engine received in an engine room covered by a water-proof engine cover. The engine cover has a fresh air intake hole for taking fresh air into the engine room. The fresh air taken into the engine room is fed into an air intake device connected to each combustion chamber of the engine. The vertical engine includes a pulley mounted to the upper end of a crankshaft for driving an alternator via an endless belt trained around the pulley and a driven pulley mounted on the alternator. The pulleys and the endless belt are covered by the engine cover.
One example of the outboard motors is disclosed, for example, in Japanese Patent Laid-open Publication No. 6-33790 entitled “Ship Propulsive Machine”. The disclosed ship propulsive machine has a top cowl in which an engine body is received. The top cowl is formed with a fresh air intake hole at which fresh air is taken into an engine room. The fresh air taken into the engine room is drawn into the engine body through an air inlet. An alternator is disposed at a position offset from a path along which the fresh air flows from the fresh air intake hole to the air inlet. The alternator is covered by a water-proof cover only at an upper portion thereof.
In the ship propulsive machine, however, since no consideration is given to exhausting of the stale air from the alternator, effective cooling of the alternator is difficult to achieve. Furthermore, due to hot air tending to fill up the top cowl without venting, the atmospheric temperature inside the engine room readily goes up and thus raises the intake air temperature of the engine. This may form a strong obstruct to the increase of the engine power output.
SUMMARY OF THE INVENTION
With the foregoing problem in view, it is a first object of the present invention to provide an outboard motor which is capable of controlling the flow of air in the vicinity of an alternator to enable effective cooling of the alternator.
A second object of the present invention is to provide an outboard motor which can perform effective ventilation of a belt cover.
To attain the foregoing object, an outboard motor according to the present invention comprises an engine cover defining an engine room and having an air intake hole for taking fresh air into the engine room, an engine block having a crankshaft rotatably supported in a vertical position within the engine room, a drive pulley mounted to an upper end portion of the crankshaft, an alternator having a driven pulley connected in driven relation to the drive pulley via an endless belt extending around the drive and driven pulleys, and a belt cover covering the drive and driven pulleys, the endless belt and at least an upper portion of the alternator. The alternator has a plurality of cooling fans for taking the fresh air into the interior of the alternator to cool the alternator. The belt cover has a multiplicity of air passage holes formed in an upper portion extending around the alternator.
The alternator is continuously driven by the engine while the engine is running. During that time, the cooling fans of the alternator rotate continuously. The fresh air taken from the fresh air intake hole into the engine (namely, the outside air having a temperature lower than that of the air inside the engine room) is caused by the cooling fans to flow through the multiplicity of air passage holes into the belt cover to cool the alternator.
The outboard motor may further include a ventilating fan mounted to the upper end portion of the crankshaft for ventilating the interior of the belt cover, a vent hole formed in the belt cover for discharging the fresh air from the engine room to the outside of the outboard motor after the fresh air is engaged in the cooling of the alternator, and at least one guide wall provided inside the belt cover at a position between the drive pulley and the driven pulley for guiding the fresh air toward the vent hole in such a way to bypass the endless belt as the fresh air is discharged from the engine room.
In the belt cover, two air flows are produced one by a ventilating action of the ventilating fan and the other by drawing and discharging actions of the cooling fans. The second-mentioned air flow is more intensive than the first-mentioned air flow. However, by virtue of the guide wall, no direct influence is exerted from the second-mentioned air flow (produced by the cooling fans) on the first-mentioned air flow (produced by the ventilating fan). The thus controlled two air flows can be smoothly discharged from the engine room, so that the interior of the belt cover is sufficiently ventilated.
The above and other object, features and advantages of the present invention will become manifest to those versed in the art upon making reference to the detailed description and accompanying sheets of drawings in which a preferred structural embodiment incorporating the principles of the present invention is shown by way of illustrative example.
REFERENCES:
patent: 4874959 (1989-10-01), Sheridan
patent: 5370563 (1994-12-01), Yamazkai et al.
patent: 5445547 (1995-08-01), Furukawa
patent: 5503577 (1996-04-01), Ming et al.
patent: 5921827 (1999-07-01), Ichihashi
patent: 6-33790 (1994-02-01), None
Haga Nobuo
Tawa Hiroki
Adams & Wilks
Honda Giken Kogyo Kabushiki Kaisha
Morano S. Joseph
Wright Andy
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