Internal-combustion engines – Two-cycle – Rear compression
Patent
1993-10-25
1995-01-03
Cross, E. Rollins
Internal-combustion engines
Two-cycle
Rear compression
F01M 100
Patent
active
053776372
DESCRIPTION:
BRIEF SUMMARY
This invention relates to the control of the supply of oil to a two stroke cycle engine wherein the introduction of the oil to the engine is separate from the introduction of the fuel.
With the increasing requirement to reduce the emissions of internal combustion engines, it has been recognised that controls must be introduced in respect of the level of exhaust emission from a range of engines other than automotive engines, particularly in regard to marine engines for pleasure craft and engines for motor bikes and motor scooters. There are also under consideration restrictions on the emissions from various forms of stationary internal combustion engines and equipment employing relatively small capacity internal combustion engines such as lawn mowers and bush cutters.
A large proportion of these small engines operate on the two stroke cycle principle, primarily because of the relatively low weight and cost of manufacture of two stroke cycle engines. However, the majority of two stroke cycle engines currently in use effect lubrication of the engine by introducing lubricating oil into the fuel which then passes through the crankcase compartment of the respective cylinders before the fuel enters the cylinder to be ignited and combusted. Although the mixing of the oil with the fuel is very convenient and a relatively cheap means of conveying the lubricating oil to the various areas of the engine, it does aggravate the problem of exhaust emissions.
Mechanical oil metering devices are also used in conjunction with two stroke cycle engines, usually controlled from the throttle linkage to regulate the oil supply relative to engine load. The oil is delivered into the fuel or directly into the engine, or in a crankcase compression two stroke cycle engine into the air in the crankcase.
It has been established that the most effective control of exhaust emissions, particularly in two stroke cycle engines, is attained by directly injecting the fuel into the combustion chamber, however, with such direct injecting systems, the fuel may not be used as the carrier for the lubricating oil, as the fuel does not enter the engine crankcase where the principal components requiring effective lubrication are located.
In automobiles having relatively large capacity engines, it is economically acceptable to provide an engine management system incorporating an electronic control unit which can be programmed to control an appropriate lubrication system for the engine, in addition to controlling the operation of the fuel injection system. However, the costs of such engine management systems are too high to permit the use thereof in controlling the operation of low cost small capacity engines such as small marine engines, motor bike and scooter engines and lawnmower engines.
It is therefore the object of the present invention to provide a method and apparatus for the supply of fuel and lubricant to a two stroke cycle internal combustion engine which is effective and reliable in controlling the rate of supply of lubricant to the engine and may be manufactured in high volume at a comparatively low cost.
With this object in view, there is provided a method of control of the supply of lubricating oil to a two stroke cycle internal combustion engine comprising delivering fuel to the engine from a fuel reservoir, cyclically filling said reservoir with a quantity of fuel at least equal to the engine fuel requirement for a plurality of engine cycles at maximum engine fuel consumption rate, delivering oil to the engine by positive displacement pump means having a delivery rate per pump cycle greater than the maximum oil requirement of the engine per engine cycle, activating said oil pump in response to and simultaneously with the consumption of fuel from said reservoir, and controlling the delivery of oil during each pump cycle to maintain a substantially uniform predetermined ratio between the quantity of fuel and quantity of oil delivered to the engine per engine cycle, the method allowing oil and fuel to be delivered separately to the engine.
REFERENCES:
patent: 4403578 (1983-09-01), Iwai et al.
patent: 4539949 (1985-09-01), Walsworth
patent: 4765291 (1988-08-01), Kurio
patent: 5024190 (1991-06-01), Kameyama
patent: 5103777 (1992-04-01), Daikoku
patent: 5315971 (1994-05-01), Yamada
Hill Raymond J.
Leighton Sam R.
Pracilio Claudio
Cross E. Rollins
Macy M.
Orbital Engine Company (Australia) Pty. Limited
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