This paper deals with the transient response of a highly turbocharged gasoline engine. This downsized engine should behave as a naturally aspirated engine when the throttle is suddenly opened. However, a turbo lag occurs and this phenomenon is of large importance for the vehicle acceleration and driver sensations. To reduce turbo lag effects, an electrical compressor (E-booster) was used to improve the main compressor and engine responses.
The study was led on a three cylinder 1L turbo-charged engine.
1-D simulations (WAVE code) with a MATLAB-SIMULINK coupling were used to calculate the engine and vehicle transient responses. The vehicle, turbocharger and E-booster characteristics were simulated by the model. Second to third gear wide open throttle accelerations, varying engine loads at constant speed were also simulated.
The calculations give important results like E-booster electrical consumption, and focus on the most significant parameters.
By increasing the mass flow in the main compressor, the electrical booster largely improves the engine response. Large gains were obtained during the acceleration: the electrical booster reduces the response time from 3s to 1s.