Study On The Fuel Economy Performance Of Atkinson Cycle Engine Used For Hybrid Vehicle

Accompanied by soaring international crude oil prices and our gradually increased dependence on oil imports, the energy saving pressure on the automotive industry has been becoming more and more imminent. As the traditional internal combustion engine and the pure electric cars both have kinds of embarrassments and disadvantages, the hybrid vehicles that get the integrating advantages of the two have become the better choice for automotives. As the traditional Otto cycle engine is designed for conventional vehicles, it's already not the good choice for hybrid vehicles. However, the energy-efficient Atkinson cycle engine has been becoming the new favorite of the hybrid vehicles. In this paper, simulation and experimental method both has been used to study the fuel economy performance of the Atkinson cycle engine.First, use the BOOST software to establish a one-dimensional engine simulation model of the target engine system, and check the accuracy of the model by compared with the experimental results. Then do some analysis and calculation based on the simulation model to obtain the influence of the geometric compression ratio, valve timing and expansion ratio to the engine performance, and optimize the required geometric compression ratio and valve timing to achieve the Atkinson cycle. In order to explore the influence of the Intake system parameters to the performance of the Atkinson cycle engine, analysis and comparison for different cases of the length and diameter of the intake manifold, volume of the air intake regulator chamber on the basis of the original structure are carried out respectively to optimize the engine performance. Finally, reasonable basic parameters of the Atkinson cycle engine are given.Then, according to preliminary results of simulation optimization, transform the original 1.8 litre DVVT Otto cycle engine into the Atkinson cycle engine by changing the structure of the pistons and the location of the intake VVT. After that the new engine is transformed to the test bench to do the calibration experiment and finally get the optimized control parameters for the Atkinson cycle engine.Upon completion of Atkinson cycle engine's calibration experiment, continue with the performance experiment of the Atkinson cycle engine and finally get its performance data. By comparing with the original 1.8 litre Otto cycle engine, the comparing result shows that, after transformation, the coverage ratio of the fuel economy area at 250g/(kW?h) get increased from 3.55% to 38.10% and the fuel economy standards of the Atkinson cycle engine get increased dramatically, what is more important is that, its BSFC of 250g/(kW?h) covers the main economy fuel consumption zone of the engine used in hybrid vehicles, which could fully ensure the fuel-efficient level of hybrid vehicles.On this basis, compare Atkinson cycle engine with the original 1.8 litre Otto cycle engine through the in-cylinder combustion parameters in order to further understand the Atkinson cycle engine's operating conditions and operating characteristics of fuel-efficient mechanism, and to explore a more optimal structure design and control strategy,also to provide a more reliable basis.