Internal-combustion engines – Precombustion and main combustion chambers in series – Having combustible mixture forming means
Reexamination Certificate
1999-12-21
2001-09-11
Yuen, Henry C. (Department: 3747)
Internal-combustion engines
Precombustion and main combustion chambers in series
Having combustible mixture forming means
C123S263000, C123S305000
Reexamination Certificate
active
06286477
ABSTRACT:
TECHNICAL BACKGROUND
The present invention relates to stratified-charge direct-injection spark-induced (DISI) internal combustion engines with swirl airflows and combustion bowls in the pistons.
BACKGROUND
Forming a stratified charge air-fuel mixture through direct-injection of gasoline fuel into the cylinder of an internal combustion engine can improve fuel economy at low-load operation and reduce undesirable emissions. The quality of charge stratification depends on the design of the combustion chamber geometry, in-cylinder airflow, and the location and spray characteristics of the fuel injector. With some current fuel injection systems, a combustion chamber bowl is formed in the top wall of the piston and the fuel injector is located adjacent the side of the cylinder bore in order to reduce the injector temperature.
Internal combustion engines of this type are often called direct-injection spark-induced (DISI) engines and there are many different designs and systems known today. For example, a DISI engine with a tumble-flow of inlet air is shown in U.S. Pat. No. 5,711,269. DISI engines with a swirl-type airflows as shown, for example, in U.S. Pat. Nos. 5,259,348 and 5,553,588.
There is a need with DISI engines to improve the stratification of the fuel-air charge mixture and decrease the velocity of the air-fuel mixture at the spark plug in order to improve the ignitability of the mixture and reduce unwanted emissions. It is an object of the present invention to provide an improved DISI engine in this regard.
SUMMARY OF THE INVENTION
The present invention provides a unique combustion chamber configuration for use with an engine having a swirl-type airflow. The combustion bowl :Ln the top wall of the piston has an asymmetrical configuration. On the downstream side of the swirl airflow, the bowl is wider in order to better retain fuel droplets. On the upstream side of the swirl flow, the bowl is extended farther away from the fuel injector to form a “harbor” generally at the center of the piston where the spark plug is located. With this configuration, rich air-fuel mixtures separate from the walls of the piston and join with the air for further mixing. The air flow of both the swirl and the squish flows are reduced in and adjacent to the harbor area, thus lowering the velocity of the air-fuel mixture at the spark plug.
The axis of the fuel spray preferably is at an angle of about 30-60° from the horizontal and at an angle of about 0-15° downstream from a vertical plane including the injector and the center of the cylinder bore. The top surface of the piston is also formed to generate a strong squish near the end of the compression stroke.
Further details, objects and benefits of the present invention will become apparent from the following description of the invention when viewed in accordance with the attached drawings and appended claims.
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Han Zhiyu
Yang Jialin
Yi Jianwen
Drouillard Jerome R.
Ford Global Technologies Inc.
Gimie Mahmoud
Yuen Henry C.
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