Implementation of Atkinson Effect for Improved Fuel Efficiency of Gasoline Engine Using 1-D Simulation Software and its Validation with Experimental Data 2021-26-0053

In order to meet the challenges of future CAFE regulations & pollutant emission, vehicle fuel efficiency must be improved upon without compromising vehicle performance. Optimization of engine breathing & its impact on vehicle level fuel economy, performance needs balance between conflicting requirements of vehicle Fuel Economy, performance & drivability.

In this study a Port Fuel Injection, naturally aspirated small passenger car gasoline engine was selected which was being used in a typical small passenger car. Simulation approach was used to investigate vehicle fuel economy and performance, where-in 1D CFD Engine model was used to investigate and optimize Valve train events (Intake and exhaust valve open and close timings) for best fuel economy. Engine Simulation software is physics based and uses a phenomenological approach 0-D turbulent combustion model to calculate engine performance parameters. Engine simulation model was calibrated within 95% accuracy of test data. This model is sufficient to analyze the change in engine performance with change of valve timings. GT POWER engine model was integrated to a vehicle simulation model of small hatchback car developed using GT Drive and validated for regulatory drive cycle.

1-D simulation model was run for various combination of Intake and exhaust valve timings. Impact of individually changing each valve timing on Fuel Economy was assessed initially via Vehicle simulation model. Optimization of valve timings was carried out and after analysis Atkinson effect was observed at final timing position. Intake valve closing was delayed which reduced compression stroke. This reduced pumping effort at F.E relevant engine operating points and improved fuel consumption. Fuel economy of optimized proposal was validated against test vehicle. It was possible to fix a Non-Variable Valve Timing (VVT) Valve train without extensive hardware trials for desired performance.