Honda progressing with high-efficiency low-emission Homogeneous Lean Charge Spark Ignition (HLSI) combustion work
Honda is developing a Homogeneous Lean Charge Spark Ignition (HLSI) combustion engine as one of the key elements in its technology roadmap for a higher thermal efficiency gasoline engine. Honda reported on its basic approach in a 2013 SAE paper; Takashi Kondo of Honda R&D then presented results to date at the recent SAE 2014 High Efficiency IC Engine Symposium.
Lean burn engines using a stratified air-fuel configuration with a comparatively rich mixture in the vicinity of the spark plugs can deliver stable combustion of an overall lean mixture. Lean burn engines can deliver a higher theoretical thermal efficiency, and their higher air/fuel (A/F) ration leads to low pumping losses. However, because a comparatively rich mixture is burned during the first half of combustion, engine-out NOx emissions are not reduced sufficiently, and the emissions reduction provided by the three-way catalyst (TWC) is insufficient, Kondo noted.
Honda is striving to develop a form of lean burn with homogeneous premixture that would be able to balance low NOx emissions with stable, controllable combustion. The Honda HLSI approach seeks to take the best of conventional lean-burn (controllability and low combustion noise) and homogeneous charge compression ignition (HCCI) (ultra-Low NOx and high thermal efficiency) while avoiding the downsides of each: NOx emissions for the former and operating range, controllability and combustion noise for the latter.
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Green Car Congress: Honda progressing with high-efficiency low-emission Homogeneous Lean Charge Spark Ignition (HLSI) combustion work