Design And Development of EGR Valve Controller for Bench Test

Various emission and fuel economy norms have been introduced worldwide by governments. In India, meeting each revision of Bharat Stage (BS) emission standards and Corporate Average Fuel Economy (CAFE) norms is challenging and requires new technologies to be incorporated in IC engines. One such technology used in gasoline engines is EGR (Exhaust gas recirculation). It works by recirculating exhaust gases back into the engine in turn increasing fuel economy and reducing nitrogen oxide emissions. An electronic control unit (ECU) precisely controls EGR valve via stepper motor, regulating the flow of exhaust gases into the engine. Lead screw type unipolar stepper motor is commonly used for the same. Vehicle ECU calculates optimum EGR percentage and decides valve opening, further sequentially engaging stepper motor coils to advance or retract the EGR valve. With advancements in EGR technology there still exists few developmental challenges like operating the EGR valve on a test bench setup and simulating various test conditions. Performing these tests on an entire vehicle or engine test bed involves high capital investments. This paper demonstrates a way to develop cost effective controller which accurately operates EGR valve with similar logics as vehicle ECU. Setup is built around a microcontroller chip which acts as the brain of the system. Microcontroller sequentially engages motor coils to advance or retract the valve. System also incorporates a feedback mechanism, providing exact measurement of valve movement. Other features of the setup include Data Logging through entire cycle run and Alert System if any anomalies are detected. Versatility of the system enable it to be customised for various engines and test cycles with minor change in programming.