Ventilation system for watercraft engine

Details Ventilation system for watercraft engine Ventilation system for watercraft engine

2001-09-20

2002-12-10

Morano, S. Joseph (Department: 3617)

Marine propulsion

Means for accomodating or moving engine fluids

Cooling for engine

C123S1960CP

Reexamination Certificate

active

06491556

ABSTRACT:

PRIORITY INFORMATION
This application is based on and claims priority to Japanese Patent Applications No. 2000-284753, filed Sep. 20, 2000, No. 2001-108382, filed Apr. 6, 2001 and No. 2001-276355, filed Sep. 12, 2001, the entire contents of which are hereby expressly incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to an ventilation system for a watercraft engine, and more particularly to an improved induction system which includes a vapor return system.
2. Description of Related Art
Personal watercraft have become very popular in recent years. This type of watercraft is quite sporting in nature and carries one or more riders. A relatively small hull of the personal watercraft defines a rider's area above an engine compartment. An internal combustion engine powers a jet propulsion unit which propels the watercraft. The engine lies within the engine compartment in front of a tunnel formed on the underside of the hull. A jet propulsion unit, which includes an impeller, is placed within the tunnel. The impeller has an impeller shaft driven by the engine. The impeller shaft extends between the engine and the jet propulsion device through a bulkhead of the hull tunnel.
Typically, two-cycle engines are used in personal watercraft because two-cycle engines have a fairly high power to weight ratio. One disadvantage of two-cycle engines, however, is that they produce relatively high emissions. In particular, large amounts of carbon monoxide and hydrocarbons are produced during operation of the engine. When steps are taken to reduce these emissions, other undesirable consequences typically result, such as an increase in weight of the engine, the cost of manufacture, and/or the reduction of power.
It has been suggested that four-cycle engines replace two-cycle engines in personal watercraft. Four-cycle engines typically produce less hydrocarbon emissions an two-cycle engines while still producing a relatively high power output. However, adapting four-cycle engines for use in personal watercraft has its own engineering and technical challenges due to, at least in part, the limited space available within the hull of a personal watercraft.
A four-cycle engine utilizes a more complex lubrication system as compared with a two-cycle engine. One approach to enabling the use of a four-cycle engine in personal watercraft applications is to provide the engine with a dry sump lubrication system. A dry sump system utilizes a shallow reservoir of oil available for an oil pump as compared with the volume of oil in a wet sump system having an oil pan, thus reducing the overall height of the engine.
A four-cycle engine can also utilize a ventilation system through which blow-by gases are returned to an air induction system to be burned with an air/fuel charge in one or more combustion chambers. The blow-by gases are comprised of air/fuel mixture and/or oil leaking from a combustion chamber into the crankcase through a nominal space formed between a piston and an inner surface of a cylinder bore.
FIG. 1
illustrates a diagrammatic view of an exemplary arrangement that includes a combined lubrication and ventilation system. It should be noted that the arrangement shown in
FIG. 1
is not prior art and was developed by the inventors themselves. While the engine
28
is operating, lubricant oil that has lubricated engine portions and blow-by gases together drain downwardly to a shallow reservoir defined in the crankcase
30
of the engine
28
. A scavenge pump
32
pressurizes the oil and the blow-by gases to an oil tank assembly
34
through a scavenge passage
36
. A feed pump
38
pressurizes and thereby feeds the oil in the oil tank assembly
34
to the engine portions that need lubrication through a feed passage
40
. If the oil in the oil tank assembly
34
exceeds a preset level, the excess oil moves to a cylinder head
42
through a spillway passage
44
and thus lubricates engine components therein.
A plenum chamber
46
is coupled with the combustion chamber defined within the cylinder head
42
through an intake passage. The blow-by gases collected in the oil tank assembly
34
are drawn into the plenum chamber
46
through a ventilation passage
50
and then to the combustion chamber with a fresh air/fuel charge to be burned therein. This cycle repeats as the engine
28
operates.
SUMMARY OF THE INVENTION
One aspect of the present invention includes the realization that the arrangement illustrated in
FIG. 1
can cause a problem if used with a personal watercraft. Typically, personal watercraft are capsized and readily returned to a normal upright position during operation. However, in the arrangement thus described, the oil in the oil tank assembly
34
can flow into the ventilation passage
50
and then to the plenum chamber
46
while the watercraft capsizing. If this occurs, an air induction system including the plenum chamber
46
and the intake passage
48
can be damaged by the oil flown thereinto. Additionally, such a flow of oil into the induction system can interfere with normal operation of the engine. A need thus exists for an improved ventilation system for a watercraft engine that can inhibit the oil from flowing into an air induction system even if the watercraft capsizes.
In accordance with another aspect of the present invention, a watercraft comprises a hull. A propulsion device is configured to propel the hull. An internal combustion engine is configured to power the propulsion device. The engine includes an engine body and a moveable member moveable relative to the engine body. The engine body and the moveable member together define a combustion chamber. An air induction system is configured to guide air to the combustion chamber. A lubrication system is arranged to lubricate at least a portion of the engine body with lubricant oil. The lubrication system includes an oil container out of the engine body. A ventilation system is configured to separate a gaseous component from a liquid component. The ventilation system includes a separator configured to separate the gaseous component from the liquid component. A ventilation passage connects the separator with the air induction system. A return passage couples a bottom portion of the ventilation passage with inside of the engine body.
In accordance with yet another aspect of the present invention, a watercraft comprises a hull. A propulsion device is arranged to propel the hull. An internal combustion engine is arranged to power the propulsion device. The engine includes an engine body and a moveable member moveable relative to the engine body. The engine body and the moveable member together define a combustion chamber. An air induction system is arranged to introduce air to the combustion chamber. A lubrication system is arranged to lubricate at least a portion of the engine body with lubricant oil. The lubrication system includes an oil container out of the engine body. A ventilation system is arranged to separate a gaseous component from a liquid component. The ventilation system includes a separator configured to separate the gaseous component from the liquid component. A ventilation passage connects the separator with the air induction system. An upstream end of the ventilation passages is disposed on one side of the hull. At least a portion of the ventilation passage is disposed on the other side of the hull.
In accordance with a further aspect of the present invention, a watercraft comprises a hull. A propulsion device is arranged to propel the hull. An internal combustion engine is arranged to power the propulsion device. The engine includes an engine body and a moveable member moveable relative to the engine body. The engine body and the moveable member together define a combustion chamber. An air induction system is arranged to introduce air to the combustion chamber. A lubrication system is arranged to lubricate at least a portion of the engine body with lubricant oil. The lubrication system includes an oil container out of the engine body.

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