Internal-combustion engines – Precombustion and main combustion chambers in series – Having volumetric relation between precombustion and main...
Reexamination Certificate
2000-06-30
2001-10-23
Kwon, John (Department: 3747)
Internal-combustion engines
Precombustion and main combustion chambers in series
Having volumetric relation between precombustion and main...
Reexamination Certificate
active
06305346
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a fuel injection internal combustion engine. More particularly, this invention relates to a spark ignition internal combustion engine having a sub-combustion chamber in which mixture gas with an air-fuel ratio adapted for an engine operating state over a wide operating range of the engine is supplied to a combustion chamber. The amount of hydrogen carbide discharged is lowered, and the engine has a high efficiency.
2. Description of the Background Art
A fuel injection internal combustion engine is known in which a sub-combustion chamber is provided in communication with a main-combustion chamber, and a mixture of the fuel and compressed air is injected to this sub-combustion chamber. For example, the Official Gazette of Japanese Patent Application Laid-open No. HEI 5-195787 describes such a fuel injection type two-cycle engine.
In the engine, according to FIG. 1 of the Official Gazette above, an air fuel injecting valve for injecting the mixture of the compressed air and fuel, and a spark plug, are fitted to the sub-combustion chamber. The air fuel injecting valve is provided with a solenoid type fuel switching valve and a solenoid type mixture switching valve.
In general, in such a fuel injection two-cycle engine, on the occasion of injecting the mist of fuel from the mixture switching valve, such spraying work is assisted by the pressure of the compressed air. Therefore, the fuel of comparatively high concentration is converted to fine particles to form the adequate spraying form (spraying condition of the fuel).
However, in order to constitute a desirable spray form, the compressed air must be maintained at a high pressure, for example, 5 kg/cm
2
G or higher. More particularly, the pressure must further be increased in the case of supplying a large amount of fuel. In other words, since it is necessary to maintain the desirable spray form of the fuel, it is not easy to increase the amount of fuel to be supplied in the case of assisting the spraying effect of the fuel with low pressure compressed air. Moreover, a high pressure air pump and a high pressure fuel pump are necessary to assist the spray form of the fuel with the low pressure compressed air.
A spark ignition two-stroke cycle internal combustion engine is known which is provided with a sub-combustion chamber communicated with the main combustion chamber in order to make a positive ignition of a small amount of fuel under a low load operating state, and the mixture gas is formed in the sub-combustion chamber in a layer shape from rich mixture gas to lean mixture gas (refer to a gazette of Japanese Patent Publication No. Hei 5-195787).
In the case of the two-cycle internal combustion engine described in the aforesaid gazette, it had a disadvantage that a volume of the sub-combustion chamber was remarkably low as compared with a volume of the main combustion chamber, so that under a low load operating state, it was possible to form a small amount of fuel in the sub-combustion chamber in a stratified shape in a desired distribution of air-fuel ratio, although under a high load operating state, a large amount of fuel could not be supplied in the sub-combustion chamber in such a way that a proper air-fuel ratio might be attained. Therefore, irregular combustion was produced and a large amount of hydrogen carbide was discharged.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide the technology to enhance the combustion efficiency even when the fuel is injected with low pressure compressed air into the sub-combustion chamber from a mixture switching valve.
In order to attain the object explained above, the invention proposes a fuel injection internal combustion engine providing a sub-combustion chamber in communication with a main-combustion chamber of the internal combustion engine, and fitting a mixture switching valve to inject the mixture of the fuel and compressed air into the sub-combustion chamber. The sub-combustion chamber is formed of a material having a thermal conductivity which is lower than that of the material forming the main-combustion chamber.
Since the sub-combustion chamber is structured by a material having low thermal conductivity, the amount of heat released to the external side through the wall of the sub-combustion chamber is reduced, and thereby the inside of the sub-combustion chamber is maintained at a high temperature. Therefore, the sub-combustion chamber maintains the condition heated by the combustion gas. Since the mixture is supplied to the high temperature sub-combustion chamber, the fuel in the mixture is easily vaporized. Therefore, since the fuel is quickly vaporized even when a large amount of fuel is sprayed into the sub-combustion chamber with low pressure compressed air, and the particles of fuel are large in size, good combustion can be realized even with a non-optimum spray form, and high combustion efficiency can be attained. Moreover, since ignition is possible even when particle size of the fuel is comparatively large, lift of the valve body of the mixture switching valve can be set to a comparatively large amount.
Moreover, since it is not required to improve the quality of the spray form in order to spray the large amount of mixture into the sub-combustion from the mixture switching valve, it is not necessary to greatly enhance the accuracy of the mixture switching valve without relation to the lift amount of the valve body. Therefore, the cost of the mixture switching valve and valve control system can be lowered.
Since the spray form of the fuel can be supported by the low pressure compressed air, a low pressure air pump and a low pressure fuel pump can be used. In the case of extracting the power of the air pump and fuel pump from the internal combustion engine, since each pump is operating at low pressure, only a low power is extracted and a large load is not applied to the internal combustion engine.
The main combustion chamber is constructed of aluminum alloy, and the sub-combustion chamber is constructed of cast iron.
Since the sub-combustion chamber is constructed of cast iron having low thermal conductivity, a small amount of heat is released to the external side through the wall of the sub-combustion chamber and as a result, the inside of the sub-combustion chamber is maintained at a high temperature. Moreover, since the main combustion chamber is constructed of an aluminum alloy, the internal combustion engine is lightweight. Therefore, although the internal combustion engine is lightweight, since the fuel is quickly vaporized if a large amount of fuel is sprayed to the sub-combustion chamber with low pressure compressed air, good combustion condition can be realized with higher combustion efficiency with the spray form even if it is not in the optimal form.
The present invention further relates to an improvement of the spark ignition internal combustion engine which is comprised of a sub-combustion chamber communicated with a main combustion chamber, an injecting means for directly and intermittently injecting mixture gas into the sub-combustion chamber, and an igniting means arranged in the sub-combustion chamber. Each of ratios of volumes of the sub-combustion chamber and the main combustion chamber is set within a range of 1:4 to 3:2.
The present invention is constructed as described above in which a volume of the sub-combustion chamber is not set to such a higher ratio as compared with a volume of the main combustion chamber, so that under a low load operating state in which a small amount of fuel is supplied to the combustion chambers, the mixture gas with a proper distribution of air-fuel ratio is formed in the sub-combustion chamber in a stratified shape. Ignition is positively performed, irregular combustion is avoided and a discharging amount of hydrogen carbide is restricted.
Under a high load operation state in which a large amount of fuel is supplied to the combustion chambers, such rich mixture gas as one not producing any irreg
Nishikawa Yutaka
Takada Yoshihiro
Tsushima Yuji
Ueda Minoru
Yamashita Hiroshi
Birch & Stewart Kolasch & Birch, LLP
Honda Giken Kogyo Kabushiki Kaisha
Kwon John
LandOfFree
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