Internal-combustion engines – Precombustion and main combustion chambers in series – Having combustible mixture forming means
Patent
1983-09-28
1985-09-03
Argenbright, Tony M.
Internal-combustion engines
Precombustion and main combustion chambers in series
Having combustible mixture forming means
123193P, 123279, F02B 1908
Patent
active
045385661
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
Technical Field
The present invention relates to a combustion chamber in a diesel engine, and more particularly to a combustion chamber in a diesel engine, which is defined by a cavity of a specific shape formed in a top surface of a piston.
Background Art
Diesel engines have pistons with cavities defined in their top surfaces and fuel nozzles for injecting fuel into the cavities. With such direct-injection type diesel engines, various attempts have been made to provide combustion chamber configurations to improve the condition of combustion in the combustion chambers.
One known prior art will be described which is directed to an improved combustion chamber configuration for improving combustion.
FIG. 1 of the accompanying drawings is illustrated in Japanese Patent Publication No. 56-28210. A cavity 2 is defined in a top surface of a piston 1 with a restriction 3 disposed at an inlet of the cavity 2. The restriction 3 is small with D.sub.1 /D.sub.2 =0.85-0.98 according to the Publication.
The restriction 3 according to the prior art shown in FIG. 1 has the following advantages:
On the compression stroke of the piston 1, air is caused to flow in the directions of the arrows S.sub.1 from a zone Z surrounded by a peripheral portion of the piston 1 and a cylinder head 4 into a combustion chamber 5 immediately before the piston 1 reaches its top dead center. The flows S.sub.1 are normally referred to as squishing streams. These squishing streams serve to disturb a swirl S in the combustion chamber 5 to provide an improved mixture of air and fuel injected from a fuel injection nozzle 6. The squishing streams S.sub.1 are also created when the fuel starts being combusted as the piston is in the vicinity of the top dead center. More specifically, when fuel starts to be injected, the fuel begins being combusted at a few locations in the combustion chamber 5. The pressure in the combustion chamber 5 is abruptly incrased to force the combustion gas in the combustion chamber 5 to flow back into the zone Z in the directions of the arrows S.sub.2, these gas flows being referred to as counter squishing streams. The counter squishing streams S.sub.2 are kept by the restriction 3 in the combustion chamber for a certain period ot time, and thereafter are allowed to flow abruptly into the zone Z as the streams S.sub.2. This increases the rate of utilization of air in the zone Z and improves the combustion efficiency due to rapid combustion.
Another example of an improved combustion chamber configuration will be described. FIGS. 2 and 3 are shown in U.S. Pat. No. 3,302,627. A cavity 12 is defined in a top surface of a piston 11 and has lateral ridges 13 which makes the cavity 12 petal-shaped with four petals. Atomized fuel streams P.sub.1 -P.sub.4 from a fuel nozzle 14 are oriented off the ridges 13 in the direction of a swirl S, that is, downstream of the ridges 13 in the direction of the swirl S.
The conventional combustion chamber 15 enables the ridges 13 to produce fuel streams S.sub.3 directed to the center of the combustion chamber 15 and acting to develop an improved mixture of fuel and air in the combustion chamber 15.
The prior art constructions however fail to provide effective matching between the direction of fuel injection and the position of arrival of atomized fuel through the shape of the combustion chamber and the fuel nozzle.
DISCLOSURE OF THE INVENTION
It is an object of the present invention to provide a combustion chamber construction in a diesel engine for reducing HC in the exhaust gas to thereby improve fuel economy and reduce harmful pollutants in the exhaust gas.
According to the present invention, a cavity defining a combustion chamber has recesses in its side surface, and fuel is injected toward various portions of the side face of the cavity.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a vertical cross-sectional view of a known combustion chamber;
FIG. 2 is a vertical cross-sectional view of another known combustion chamber;
FIG. 3 is a plan view showing the piston in FIG.
REFERENCES:
patent: 2975773 (1961-03-01), Meurer
patent: 3144008 (1964-08-01), List
patent: 4083330 (1978-04-01), Morris
Argenbright Tony M.
Hino Jidosha Kogyo Kabushiki Kaisha
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