Method and system for a hc trap

Abstract

Methods and systems are provided for a HC trap in a bypass passage. In one example, a method may include closing a diverter valve to flow exhaust gas from a main exhaust passage to the bypass passageduring a cold-start.

Description

technical field [0001] The present invention generally relates to integrated hydrocarbon traps and catalysts. Background technique [0002] In recent years, considerable efforts have been made to reduce the levels of hydrocarbon (HC) emissions from vehicle engines. Conventional exhaust treatment catalysts, such as three-way catalysts, effect the oxidation of hydrocarbons to CO2 and water and help prevent unburned or partially burned hydrocarbon emissions from leaving the vehicle. However, these emissions are high during engine cold start before the latent heat of the exhaust gas allows the catalyst to activate (eg, reach light-off temperature). [0003] Attempts to reduce emissions during engine cold starts may include providing an auxiliary heating device to heat the catalyst to light-off temperature. Other attempts to address engine cold start emissions include integrating a hydrocarbon trap (HC trap) with the catalyst. An example approach is shown by Jen et al. in U.S....

AI Technical Summary

Problems solved by technology

This problem is further exacerbated as the HC trap releases HC at lower temperatures and the catalyst ignites at higher temperatures due to continued use during the life of the HC trap

Therefore, the HC trap system may not adequately reduce emissions during cold starts

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