Internal-combustion engines – Precombustion and main combustion chambers in series – Having combustible mixture forming means
Reexamination Certificate
1999-05-11
2001-12-04
Dolinar, Andrew M. (Department: 3747)
Internal-combustion engines
Precombustion and main combustion chambers in series
Having combustible mixture forming means
C123S256000, C123S0270GE
Reexamination Certificate
active
06325039
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a combined engine which is capable of utilizing either gas fuel or liquid fuel by means of selecting the appropriate operational mode, and which is applied mainly towards generating electricity. This application is based on an patent application No. Hei 10-130849 filed in Japan, the content of which is incorporated herein by reference.
2. Relevant Art
In recent years, gas engines have continued to enjoy wide usage as the key hard of co-generation system. In particular, in commercial district, due to the regulation of exhaust gas, spark-ignition gas engines with a precombustion chamber are being widely employed. On the other hand, diesel engines are also in great demand for use in fire prevention and power maintenance during times of emergency.
Conventionally, the gas and diesel engines for satisfying the aforementioned demands had to be designed separately, as different engine types, since an engine capable of providing both spark ignition and compression ignition in the same engine did not exist. Consequently, a great demand exists for the preparation of a gas engine for use during normal operation, and a diesel engine for use in emergency operation, with large amounts of capital being invested accordingly.
On the other hand, a combined engine exists that is capable of operating in both a gas operational mode in which gas fuel is used, and a diesel operational mode in which liquid fuel is used. According to this type of combined engine, it is possible to selectively switch between a gas operational mode, in which gas fuel is combusted using a small amount of pilot oil (approximately 5~15% of the entire fuel amount) as the ignition source, and a diesel operational mode, in which only liquid fuel is combusted. With regard to this engine, at the time of starting the engine, the engine is started and warmed-up by means of liquid fuel which possesses a superior ignitability. After the engine is warmed-up, at the stage where the engine operational load factor reaches at least 30%, by switching from liquid fuel to gas fuel, the highly ignitable liquid fuel that is used as the pilot fuel is supplemented by ignition of the less ignitable gas fuel.
However, according to the conventional combined engines, due to the use of liquid fuel as the pilot fuel, in an amount of approximately 5~15% of the entire heating amount, there exists a limit with regard to the NOx, as well as the fall in soot and dust.
In consideration of the aforementioned, it is an object of the present invention is to provide a combined engine and method for operating the same which is capable of utilizing either gas fuel or liquid fuel, while also reducing the equipment costs and decreasing the amount of pollution therefrom.
SUMMARY OF THE INVENTION
Accordingly, the present invention provides a combined engine which receives a drive output by means of supplying and combusting at least one fuel selected from among a gas fuel and a liquid fuel, said engine comprising: a main combustion chamber which comprises a piston, a cylinder and a cylinder head; a precombustion chamber equipped with a spark plug which serves as an ignition source for a fuel-air mixture comprising air and the gas fuel within the main combustion chamber; and a liquid fuel injection valve for injecting liquid fuel into the main combustion chamber; wherein, the precombustion chamber and the liquid fuel injection valve are provided in the cylinder head.
In addition, according to the present invention, a method for operating a combined engine, as a spark ignition gas engine, is provided which comprises the steps of: supplying a fuel-air mixture comprising gas fuel and air to the main combustion chamber; supplying a pilot gas to the spark plug-equipped precombustion chamber, and spark igniting the pilot gas by means of the spark plug; and combusting the fuel-air mixture within the main combustion chamber using the spark plug-equipped precombustion chamber as an ignition source.
In addition, according to the present invention, a method for operating a combined engine, as a diesel engine, is provided which comprises the steps of: injecting, from a predetermined distance, a liquid fuel from the liquid fuel injection valve into the main combustion chamber; and compression-igniting the liquid fuel injected into the main combustion chamber.
In addition, according to the present invention, a method for operating a combined engine, as a pilot injection gas engine, is provided which comprises the steps of: supplying a fuel-air mixture comprising gas fuel and air to the main combustion chamber; injecting a small amount of liquid fuel from the liquid fuel injection valve into the main combustion chamber; compression-igniting the liquid fuel injected into the main combustion chamber; and combusting the fuel-air mixture within the main combustion chamber using the compression-ignited portion as an ignition source.
In addition, according to the present invention, a method for operating a combined engine, as a hybrid ignition gas engine that is capable of utilizing both gas fuel and liquid fuel, is provided which comprises the steps of: in the same combustion cycle, supplying a fuel-air mixture comprising gas fuel and air to the main combustion chamber; supplying a pilot gas to the spark plug-equipped precombustion chamber, and spark igniting the pilot gas by means of the spark plug; injecting a small amount of liquid fuel from the liquid fuel injection valve and compression-igniting the liquid fuel at approximately the same timing, or alternatively before or after the spark-ignition; and combusting the fuel-air mixture within the main combustion chamber using the spark-ignited and compression-ignited portions as ignition sources.
Furthermore, according to the present invention, a method for operating a combined engine is provided which comprises the steps of: during times of normal operation, supplying a fuel-air mixture comprising gas fuel and air to the main combustion chamber; supplying a pilot gas to the spark plug-equipped precombustion chamber, and spark igniting the pilot gas by means of the spark plug; combusting the fuel-air mixture within the main combustion chamber using the spark plug-equipped precombustion chamber as an ignition source; wherein, at the time when an ignition abnormality of the spark plug-equipped precombustion chamber is detected due to a change in the exhaust temperature, another operational process is performed which differs from that performed in the operational mode during times of normal operation.
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Dolinar Andrew M.
Fish & Richardson P.C.
Niigata Engineering Co. Ltd.
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