Exhaust gas temperature for knock detection and control in spark ignition engine

Knock is a major problem limiting the development of efficient and powerful engines in both design and operating stages. It is objectionable due to its damage on engine elements. Without knock, an engine can be designed to have a higher compression ratio, giving higher efficiency and power output. Since knock is a factor of concern, many researches have been done to eliminate and control knock. To date, knock has been detected using an accelerometer or an in-cylinder pressure transducer. These types of sensors have some drawbacks. In this paper, a new sensor for detecting knock is presented. It uses the exhaust gas temperature as an engine variable and utilizes the fact that this variable decreases a considerable amount when the engine goes into knock. Thus, be locating a temperature sensor at the exhaust port of the engine, the exhaust gas temperature can be measured, and the onset of knock can be detected. It is observed that, under knock conditions the exhaust gas temperature showed favorable results toward correlating engine knock with a drop in the exhaust gas temperature. Also, a suggested control system is presented in this paper. This system could be used in conjunction with the sensing system to move the engine away from the knocking regime.