Internal-combustion engines – Lubricators – Crankcase – pressure control
Reexamination Certificate
1999-08-18
2001-11-20
Wolfe, Willis R. (Department: 3747)
Internal-combustion engines
Lubricators
Crankcase, pressure control
C123S1960CP
Reexamination Certificate
active
06318331
ABSTRACT:
RELATED APPLICATIONS
This invention claims priority to Japanese Application No. 10-231246, which was filed on Aug. 18, 1998.
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to an engine lubricating system and has particular applicability to a fuel injected two cycle engine.
2. Description of the Related Art
Two cycle internal combustion engines are typically lubricated by supplying lubricant through the engine's induction and porting system for lubricating the various moving components of the engine. Lubricant can be supplied in a wide variety of manners. For example, lubricant may be mixed with fuel, may be sprayed into the induction system of the engine, may be delivered directly to certain components of the engine, or may be supplied by any combination of the above.
In conventional two cycle engines, air from an air intake system travels through reed valves into a crank chamber of the engine. Air from the crank chamber is supplied to the cylinders for combustion. Typically, fuel such as gasoline is mixed with lubrication oil and supplied to the air flow on an upstream side of the reed valves. The viscosity of this fuel/lubricant mixture is low in comparison with a typical lubricant taken alone. Because of its low viscosity, the mixture is easily sprayed and distributed to various parts of the engine for lubrication.
In order to reduce unburned hydrocarbons and engine exhaust emissions, many internal combustion engines now employ direct fuel injection, wherein the fuel is directly injected into the cylinders. In these engine arrangements, the fuel is not mixed with lubricant. As a result, the viscosity of the lubricant is increased and the lubricant is not smoothly sprayed and distributed. Due to its heavy viscosity, when lubricant is supplied upstream of the reed valves, lubricant particles tend to stick together when passing through the valves. The large particles increase lubricant inconsistency, possibly preventing even distribution of lubricant over the engine components.
Lubricant in the crankcase chamber is distributed to the various components of the engine, for instance the pistons and cylinder areas. In two cycle engines, lubricant also typically flows into the scavenging passages. At least some of the lubricant that collects in the scavenge passages may flow into a cylinder combustion chamber and be at least partially burned. Invasion of oil into the combustion chamber at least partially defeats the purpose of fuel injection by contributing additional hydrocarbon exhaust emissions, which direct fuel injection is intended to reduce.
In outboard motor applications, the engine is normally positioned with its cylinders extending horizontally and crankshaft rotating about a vertically extending axis. As is typical with two cycle engines, each crankcase chamber is sealed from the other. However, the seals may permit some leakage from the uppermost crankcase chamber to the lowermost chamber and lubricant may tend to collect in the lowermost portions of the engine. This can cause inadequate lubrication in the uppermost portions and oil overflow in the lower portions. Performance of the engine is decreased.
SUMMARY OF THE INVENTION
Accordingly, there is a need in the art for a two cycle fuel injection engine lubrication system adapted to evenly distribute lubricant to the moving components of the engine, to drain lubricant that may accumulate in scavenge passages, and to prevent excess oil from accumulating in the lowermost portions of the engine.
In accordance with one aspect of the present invention, an internal combustion engine is provided having at least one variable volume combustion chamber. The combustion chamber is defined by at least a pair of components that move relative to each other. A crankcase encloses a crankshaft and has an air guide. The air guide communicates with an air intake device through a valve that regulates air flow into the crankcase. The air guide also has a lubricant insertion port immediately adjacent a downstream side of the valve.
Another aspect of the present invention involves an internal combustion engine having at least one variable volume combustion chamber. The combustion chamber is defined by at least a pair of components that move relative to each other. A crankcase encloses a crankshaft and has an air guide which communicates with an air intake device through a valve that regulates air flow into the crankcase. The crankcase further includes means for inserting lubricant immediately adjacent a downstream side of the valve and means for distributing lubricant in the crankcase.
In a still further aspect of the present invention, an internal combustion engine is provided having at least one variable volume combustion chamber. The combustion chamber is defined by at least a pair of components that move relative to each other. A crankcase encloses a crankshaft therein. The crankcase has an air guide which communicates with an air inlet device and conducts a flow of air into the crankcase. A scavenge system supplies supply air from the crankcase to the combustion chamber. The scavenge system includes means for conducting lubricant way from the scavenge system.
The above-discussed aspects of the invention are particularly well suited with engines operating on a crankcase compression, two-cycle combustion principle; however, many of the disclosed aspects of the invention can also be used with engine types that operate on other combustion principles.
For purposes of summarizing the invention and the advantages achieved over the prior art, certain objects and advantages of the invention have been described herein above. Of course, it is to be understood that not necessarily all such objects or advantages may be achieved in accordance with any particular embodiment of the invention. Thus, those skilled in the art will recognize that the invention may be embodied or carried out in a manner that achieves or optimizes one advantage or group of advantages as taught herein without necessarily achieving other objects or advantages as may be taught or suggested herein.
All of these aspects and features are intended to be within the scope of the invention herein disclosed. These and other aspects, features and advantages of the present invention will become readily apparent to those skilled in the art from the following detailed description of the preferred embodiment having reference to the attached figures, the invention not being limited to the particular preferred embodiment disclosed.
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Hiraoka Noriyoshi
Takashima Kazutoshi
Benton Jason
Knobbe Martens Olson & Bear LLP
Sanshin Kogyo Kabushiki Kaisha
Wolfe Willis R.
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