Internal-combustion engines – Two-cycle – Rear compression
Reexamination Certificate
1999-10-13
2001-09-04
Argenbright, Tony M. (Department: 3747)
Internal-combustion engines
Two-cycle
Rear compression
C123S1960CP
Reexamination Certificate
active
06283072
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to the field of two-stroke internal combustion engines in which the oil is injected independently of the gasoline. These engines are also called engines with separate lubrication.
More specifically, the invention describes the monitoring of the flow rate, or metering, of the oil that is injected into this type of engine.
2. Description of the Prior Art
The known systems for oil metering generally comprise a mechanical metering pump that is controlled based on parameters such as the engine speed and/or the position of the gas throttle valve, representing the load of the engine.
These parameters, which are now used to control the metering of oil, have several drawbacks, particularly in the case of air-cooled engines. They do not make it possible, in particular, to ensure good metering regardless of the load and/or the speed of the engine. In particular, metering is unsuitable when the thermal level of the engine varies: when climbing a steep grade or in the event of a failure of the cooling system, for example.
Improvements have therefore already been proposed, such as, for example, in Patent Application EP-A1-0577081. According to this document, it is possible to readjust the amount of oil that is injected based on thresholds stored in a computer memory; it is also possible to vary the length of time between injections.
This technological solution is based primarily on the load and speed values of the engine.
SUMMARY OF THE INVENTION
The present invention is based on a different technical choice. The invention uses monitoring of the oil flow rate based on the temperature of an element of the engine that represents the heat load level of the engine.
This solution makes it possible to achieve reliable and accurate metering which, by ensuring better management, makes it possible to reduce oil consumption considerably, on the order of 30% to 50%.
There may be a very significant risk of deterioration of the engine in the event of defects in the cooling system or major overheating.
To resolve these kinds of problems, the current lubrication systems are designed to guarantee a margin of safety in the event of major overheating of the engine (climbing of a long grade, for example).
These adjustments therefore lead to over-consumption of oil when the engine operates under normal conditions, which are less demanding because the safety margin exists regardless of the operating conditions.
There are currently few systems that are able to actually optimize oil consumption.
Moreover, as emphasized above, the systems with the best performance operate based on parameters such as load and/or engine speed.
Compared to these known techniques, the present invention solves the problems mentioned above, particularly those that are linked to overheating of the engine and excessive oil consumption.
Thus, this invention monitors the oil flow rate for lubricating a two-stroke internal combustion engine that comprises an oil injection circuit for lubrication; said process influences the oil flow rate for lubrication based on a temperature that represents the heat load of the engine.
More specifically, the temperature that represents the heat load is the temperature of an element that constitutes part of said engine.
According to the invention, the engine comprises an ignition element that is equipped with a gasket.
In accordance with this embodiment of the invention, the temperature that represents the heat load of the engine is the temperature of said gasket.
Within the scope of the invention, the temperature that represents the heat load of the engine is the temperature of the ignition element.
In particular, the flow rate of lubricating oil that is injected into the engine is increased when the temperature that represents the heat load of the engine exceeds a predetermined threshold value is increased is increased.
Furthermore, when the oil injection circuit comprises a leak circuit, the lubricating oil flow rate can be influenced by controlling the closing of said leak circuit.
Additionally, the oil flow rate is influenced based on the mechanical load and/or the speed of the engine.
The invention is also a two-stroke internal combustion engine that comprises a circuit for injecting a lubricating oil flow.
Characteristically, the engine comprises:
a sensor for measuring a temperature that represents the heat load of said engine which feeds to an output a signal that represents said temperature,
a module for processing said signal, equipped with an input that is connected to the output of the sensor for measuring said temperature and an output which issues a control signal,
means for adjusting the lubricating oil flow rate, equipped with an input that is connected to the output of the processing module,
whereby said adjusting means reacts to the control signal that is shaped by the processing module in such a way that the lubricating oil flow rate is modified based on a temperature that represents the heat load of the engine, measured by said temperature sensor, which is placed on a constituent element of said engine.
According to an embodiment of the invention, the engine is cooled by air and comprises an ignition element that is equipped with a gasket, and the sensor for measuring the temperature that represents the heat load of the engine is then placed on said gasket.
The engine which, according to the invention, comprises an ignition element, has the sensor for measuring the temperature placed on said ignition element.
In addition, the engine according to the invention can comprise a sensor for measuring the load and/or a sensor for measuring the speed of said engine, whereby the output of each of them is connected to an input of said processing module in such a way that the lubricating oil flow rate is also modified based on the load and/or the speed of the engine.
This invention will be better understood, and other elements, details, and characteristics will become clearer from reading the following description, which is given by way of illustration and is in no way limiting, in reference to the accompanying figures:
REFERENCES:
patent: 5313849 (1994-05-01), Miyata et al.
patent: 5355851 (1994-10-01), Kamiya
patent: 508486A1 (1992-10-01), None
patent: 2127694 (1972-10-01), None
Girard Philippe
Ishibashi Yoichi
Lavy Jacques
Antonelli Terry Stout & Kraus LLP
Argenbright Tony M.
Elf Antar France
Harris Katrina B.
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