Marine propulsion – Screw propeller – Propulsion unit casing
Reexamination Certificate
2000-04-27
2001-10-02
Sotelo, Jesus D. (Department: 3617)
Marine propulsion
Screw propeller
Propulsion unit casing
C440S08800J
Reexamination Certificate
active
06296536
ABSTRACT:
PRIORITY INFORMATION
This application is based on and claims priority to Japanese Patent Application Nos. Hei 11-119573, filed Apr. 27, 1999, and Hei 11-119575, filed Apr. 27, 1999, the entire contents of which are hereby expressly incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a cowling for an outboard motor, and more particularly to an air intake construction of the cowling.
2. Description of Related Art
A typical outboard motor employs an internal combustion engine for powering a propulsion device such as a propeller. A protective cowling normally encloses the engine therein to present a neat appearance but also to protect the engine. The cowling protects the engine from being wetted by the water in which the outboard motor is operated. Water, especially salt water, tends to damage engine components.
The protective cowling defines a generally closed cavity in which the engine is contained. The engine, however, must be supplied with copious amounts of air through an air induction device for combustion in its combustion chambers. For this purpose, the air induction system of the engine has an air inlet opening that is open to the cavity within the cowling. Conventionally, the protective cowling includes a rearwardly positioned, generally upwardly facing air intake duct that permits air flow into the cavity. The intake duct usually extends in an additional small cavity, which defines an air compartment. Air flow through the duct often is normal to the direction of air flow into the air compartment to cause water to drop out of the air flow before the air moves through the duct. This arrangement thus inhibits water from entering the main cavity of the cowling; however, it does not entirely prevent water from entering the cavity through the duct.
The air inlet opening of the engine induction system is normally positioned at a front portion of the cavity. Thus, the air must travel across the engine body from the air duct to the air inlet opening. This air flow advantageously cools various engine components, but it is also warmed through this process, which reduces charging efficiency. This problem is exacerbated with outboard motors employing four-stroke engines at these engines tend to run hotter than two-stroke engines.
SUMMARY OF THE INVENTION
The present invention involves the recognition of a need for an improved cowling that can supply relatively cool air containing little or no water to the induction device. It is appreciated, however, that the solution involves more than simply placing the intake duct in the vicinity of the induction system inlet open because the exclusion of water from the inlet air charge is a formidable challenge with such an arrangement. In addition, the improved cowling construction also preferably provides an air flow across the engine to cool various engine components without reducing the charging efficiency.
One aspect of the prevent invention thus involves an improved cowling assembly for an outboard motor. The outboard motor has an internal combustion engine including an air induction device. The air induction device includes an air inlet opening. The cowling assembly comprises a cowling member defining a generally closed cavity that contains the engine. An air intake duct introduces ambient air into the cavity. The air intake duct adjoins the air inlet opening. The intake duct has an opening that is opened to the cavity and positioned generally lower than a lower end of the air inlet opening.
In accordance with another aspect of the present invention, a cowling assembly has at least one front air intake opening formed on a side surface of its front portion and a rear air intake opening formed on a rear surface of a rear end portion.
Further aspects, features and advantages of this invention will become apparent from the detailed description of the preferred embodiments which follow.
REFERENCES:
patent: 4571193 (1986-02-01), Takada et al.
patent: 4952180 (1990-08-01), Watanabe et al.
patent: 4968276 (1990-11-01), Hashimoto
patent: 5181870 (1993-01-01), Arai et al.
patent: 5340343 (1994-08-01), Kawamukai et al.
patent: 5873755 (1999-02-01), Takahashi et al.
patent: 5928043 (1999-07-01), Rinzaki
patent: 60161187 (1994-01-01), None
Ishida Hitoshi
Katayama Goichi
Kawai Takaji
Takahashi Masanori
Knobbe Martens Olson & Bear LLP
Sanshin Kogyo Kabushiki Kaisha
Sotelo Jesus D.
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