Marine propulsion – Jet drive
Reexamination Certificate
1997-10-14
2001-01-09
Avila, Stephen (Department: 3617)
Marine propulsion
Jet drive
C440S08800J
Reexamination Certificate
active
06171158
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates in general to a small watercraft, and in particular to a cooling system for a small watercraft.
2. Description of Related Art
Personal watercrafts have become popular in recent years. Jet propulsion units usually power such watercrafts and offer a number of advantages over propeller driven systems. One such advantage is the ability to run in very shallow water. The jet propulsion units can also supply pressurized cooling water to an open-loop cooling system for the engine and the associated exhaust system.
For this purpose, watercraft today commonly include a delivery conduit which extends between the jet propulsion unit and a water jacket of the engine. The delivery conduit is connected to a water influent port which normally communicates with the pressure chamber of the propulsion device. Pressurized water within the chamber flows into the influent port and into the delivery conduit. The cooling water thence flows through the engine and exhaust system water jackets, and is discharged overboard, usually through a telltale port and/or the exhaust system.
Although the jet propulsion unit provides an adequate source of pressurized water, such water is not always free from foreign debris. Frequently foreign objects and particles may be drawn into the jet propulsion unit, especially when the jet propulsion unit operates in shallow water. Such foreign and small articles and objects often include such matter as weeds, small pebbles and stones, small pieces of driftwood and like debris. If the jet propulsion unit draws in such articles and the articles become entrained in the water flow through the jet propulsion unit, the foreign articles often enter the delivery conduit and clog, either partially or entirely, the water flow through the cooling system. As a result, an adequate supply of cooling water may not be delivered to the engine and the associated components, such as for example, the exhaust system. Overheating of the engine and exhaust system thus can result. Operating the engine and exhaust system at elevated temperatures can of course significantly reduce the performance of the engine, and under some conditions can possibly damage the engine.
Some personal watercraft have employed a filter within the delivery conduit to remove foreign material. The foreign material which enters and is present in the delivery conduit upstream of the filter, however, can still clog the delivery conduit as well as the filter itself. Such an in-line filter therefore requires routine maintenance and periodic replacement, which adds to the expense and effort associated with running the watercraft. In addition, the inclusion of an in-line water filter and the associated filter housing and fittings, increases the cost of the watercraft.
SUMMARY OF THE INVENTION
A need therefore exists for a simply structured filtering arrangement which removes small articles and debris from the water flow entering the delivery line of an engine cooling system, without normally requiring periodic cleaning and replacement.
An aspect of the present invention involves a small watercraft comprising an internal combustion engine that drives a jet propulsion unit. The jet propulsion unit includes a discharge nozzle and an impeller. The impeller acts upon water within the jet propulsion unit and forces the water through the discharge nozzle. The discharge nozzle, as well as an effluent port which is formed through a housing of the jet propulsion unit, are both located downstream of the impeller. A cooling system for the engine includes a water inlet tap connected to said effluent port. The inlet tap includes a filter positioned within the effluent port and is substantially coextensive therewith. The filter includes a plurality of openings.
Another aspect of the present invention involves a jet propulsion unit comprising an impeller, a discharge nozzle, and a pump chamber. The pump chamber is positioned between the impeller and the discharge nozzle. The jet propulsion unit further comprises a water effluent port that communicates with the pump chamber and a filter that is removably installed within the effluent port. The filter is arranged to lie generally flush with an inner surface of the pump chamber. As a result, any debris, which the filter separates from the water flow through the filter, will be swept off the filter by the water flow across the filter and discharged through the discharge nozzle.
Further aspects, features, and advantages of the present invention will become apparent from the detailed description of the preferred embodiment which follows.
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Gohara Yoshihiro
Henmi Yasuhiko
Avila Stephen
Knobbe Martens Olson & Bear LLP
Yamaha Hatsudoki Kabushiki Kaisha
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