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Development of a New Intake System for a 4-Valve Lean Burn Engine
Technical Paper
925020
Sector:
Event:
24th FISITA Congress
Language:
English
Abstract
This paper describes the development of new intake port
configuration to increase the air flow rate of the new 4-valve lean
burn engine introduced in 1992.
To realize lean burn, in-cylinder turbulence must be intensified
by means of gas motions such as swirl. Thus it is necessary to
increase the air flow velocity by restricting the intake port. In
consequence, charging efficiency is reduced when the swirl control
valve (SCV) is closed and the lean burn operation is limited to
light to medium load conditions and low to medium engine speeds. To
resolve this problem, a new 4-valve lean burn engine has been
developed. Studies using laser measurement techniques were
undertaken and a new intake port configuration that optimizes swirl
inclination angle so as to maximize turbulence whilst increasing
the air flow rate during lean combustion was designed. To obtain a
homogeneous in- cylinder gas mixture, laser visualization
techniques were employed and a mixture formation control method
based on fuel supply management was accomplished.
As a result of these efforts, the new lean burn engine not only
extends the lean combustion range but also provides superior
performance while significantly lowering NOx emissions.