| 摘要 |
Secondary air is strategically introduced into a combustion chamber of an internal combustion engine event after the main combustion event to reduce HC and CO emissions. While the technique is applicable to virtually any otto cycle engine, it is particularly well-suited for use in a "rich burn" utility engine typically operating at an equivalence ratio (ER) of about 1.2 or above. Such engines start easily, run well, and emit low levels of NOx at ERs on the order of 1.2. The invention takes advantage of these benefits by admitting an air/fuel charge and allowing otto-cycle combustion to occur in at least generally the usual fashion (although at least preferably as rapidly as possible for a given engine design), using the standard fuel-rich carburetor calibration to fuel the engine. Then, a subsequent reaction process is initiated by supplying supplemental air to the engine in quantities and at times that assure reaction of the still-hot residual HC and CO products with oxygen in the supplemental air. The secondary reaction dramatically reduces HC and CO emissions while retaining NOx emissions at or near the low levels enjoyed by rich burn utility engines.
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