Optimized Engine Off Time Estimation for Cold Start Detection in Emission Diagnostics.

A cold start occurs when the engine is cranked after being off for a long time, enough for its temperature to drop down to the cold ambient levels. Cold start in an engine is a critical phase as it is characterized by elevated emissions. During a cold start, exhaust components such as catalytic converter do not operate in its optimal temperature zone leading to reduced efficiency in emission control. New regulations for engine emissions are becoming stringent for this condition, hence it is important to accurately determine cold start condition in an engine to optimize the emissions control strategy. Accurate engine off time calculation plays a crucial role in cold start detection, emissions control and On-Board Diagnostics (OBD-II) decision making. This engine off time if greater than 6 hours indicates one of the conditions to confirm a cold start. Other conditions such as Ambient temperature and coolant temperature along with the engine off time confirms a cold start. This paper presents a novel approach to calculate engine off time without any need for supplementary new hardware, leveraging detection of cold start to meet the new requirements for Cold start emission reduction strategy (CSERS) for OBD-II diagnostics. The proposed methodology utilizes Real time clock to estimate the time difference between a successful Engine Cranking and previous engine off to accurately estimate engine off time, enabling precise differentiation between a cold and a warm start.