Marine propulsion – Means for accomodating or moving engine fluids – Means for handling exhaust gas
Reexamination Certificate
1998-01-30
2001-02-06
Swinehart, Ed (Department: 3617)
Marine propulsion
Means for accomodating or moving engine fluids
Means for handling exhaust gas
Reexamination Certificate
active
06183324
ABSTRACT:
FIELD OF THE INVENTION
The present invention is an exhaust system for an engine. More particularly, the invention is an exhaust system for an internal combustion engine powering a water propulsion device of a watercraft.
BACKGROUND OF THE INVENTION
Watercraft are often powered by internal combustion engines. This is especially true of the type of watercraft known as personal watercraft.
Personal watercraft have a hull which defines an engine compartment. The engine is mounted in the engine compartment and has its output shaft arranged to drive a water propulsion of the watercraft.
The engine produces exhaust products as a by-product of the combustion of fuel. It is desirable to route this exhaust from the engine to a point external to the watercraft. Generally, an exhaust system is provided for this purpose. The exhaust system normally includes at least one exhaust pipe extending from a port through the engine leading from a cylinder to a discharge point.
Many times, little attention is given the exhaust system, with the result being a detrimental affect on engine and/or watercraft performance. For example, it is generally desirable to arrange the exhaust system so that it occupies a small amount of space. In this manner, the space occupied by the engine is minimized, and the overall size of the watercraft may be minimized lending to a light and maneuverable craft. In many instances, however, this compact arrangement results in the exhaust system having sharp turns or bends which restrict the flow of exhaust therethrough. The exhaust gas back-pressure reduces engine power, especially in two-cycle engines.
An associated problem is that when the engine has multiple cylinders, a compact exhaust system may result in the exhaust flow path corresponding to one cylinder to be different than another cylinder. When the exhaust flow paths for cylinders vary, the operating temperature of the cylinders tends to vary. The cooling and air/fuel charging needs of the cylinders then varies, complicating the design and/or operating conditions of the engine.
Also, exhaust systems for engines powering watercraft are subjected to forces which many other engines are not, especially watercraft vibration. These vibration forces have the tendency to reduce the life of the exhaust system, especially exhaust system mufflers.
An exhaust system for an engine powering a watercraft which overcomes the above-stated problems is desired.
SUMMARY OF THE INVENTION
The present invention is an exhaust system for an engine powering a watercraft. Preferably, the watercraft is of the type having a hull and a front end and a rear end The watercraft has a water propulsion device which is preferably positioned near a rear end of the hull.
The engine is connected to the hull and has an output shaft arranged in driving relationship with the water propulsion device. The engine is mounted towards the front end of the hull from the water propulsion device. The engine is of the internal combustion type, and is provided with an exhaust system for routing exhaust products to a point external to the watercraft.
In one embodiment, the engine has a body defining at least two cylinders, one of which is closer to the front end of the watercraft, and the other which is closer to the rear end. The exhaust system routes exhaust from each cylinder to a discharge at the rear of the watercraft. The exhaust system includes a first portion corresponding to the forward-most cylinder, the first portion extending towards the front end of the watercraft before extending to the rear of the watercraft, the exhaust system includes a second portion corresponding to the rear-most cylinder, this portion extending directly rearwardly.
In another embodiment, the engine has a body which is tilted and defines at least one cylinder having an axis which is offset from vertical. The engine includes an intake system extending from the body in a direction generally opposite vertical from the axis along which the cylinder(s) extend. The exhaust system routes exhaust from each cylinder to a discharge at the rear of the watercraft, and includes a portion which extends under a portion of the engine between the body or intake and a bottom of the hull.
In yet another embodiment, a fuel system associated with the engine includes a fuel tank which is generally positioned forward of the engine. A first portion of an exhaust system corresponding to at least one cylinder extends forwardly along a first side of the fuel tank and then rearwardly along a second side of the tank towards the rear of the watercraft, while a second portion of the exhaust system corresponding to one or more other cylinders extends forwardly along the second side of the fuel tank and then rearwardly along the first side of the fuel tank.
Further objects, features, and advantages of the present invention over the prior art will become apparent from the detailed description of the drawings which follows, when considered the attached figures.
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Knobbe Martens Olson & Bear LLP
Swinehart Ed
Yamaha Hatsudoki Kabushiki Kaisha
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