Research On Pneumatic-Fuel Hybrid Vehicle Modeling And Control Strategy

The problems of energy crisis and environmental pollution force the automobile industry to pay more attention on the research of new energy vehicles which are resources-saving and environmental-friendly.Against this background,the technologies of electric vehicles,gas vehicles,bio-energy vehicles,fuel cell vehicles and solar-powered vehicles make great achievements recently.This paper presents a novel pneumatic-fuel hybrid vehicle power system,which has a low emission and energy consumption.The pneumatic-fuel hybrid propulsion system combines the advantages of both air-powered engine(APV)and internal combustion engine(ICE)to improve the energy efficiency of the vehicle.In this paper,the APV valve timing control strategy is proposed based on the mathematical model;the hybrid system structure and control strategy are introduced and the driving performance of the hybrid system under specific driving cycle is simulated;a novel variable valve train suitable for APV is designed and tested.The main contents and conclusions are as follows:1)The mathematical model of APV is established through thermodynamics analysis.The sensitivity analysis method is used to evaluate the influence of the valve timing on engine performance.It is found that the intake valve opening angle(IVO)and exhaust valve opening angle(EVO)have little effect on the engine performance and can be ignored during operation.To simplify the optimization process,the intake valve closing angle(IVC)and exhaust valve closing angle(EVC)are selected as main optimization objects.The maximum efficiency of APV and corresponding valve timing under certain intake pressure,speed,and torque is calculated through simulation,which provides guidance for the control of the APV.2)The pneumatic-fuel hybrid system structure and control strategy are introduced based on the characteristics of APV and ICE.The hybrid power system is modeled and simulated under New European Driving Cycle(NEDC).The simulation shows that the pneumatic-fuel hybrid vehicle can decrease the oil consumption by 40.19%and energy consumption by 25%,which indicates that the pneumatic-fuel hybrid vehicle has great potential on energy saving.3)A novel high-pressure pneumatic proportional,variable valve train is designed to meetthe demand of the APV.Optimization of the key parameters of the valve train is conducted based on the mathematical model.The experiment on the valve train shows that the minimum movement time is less than 10ms,means that the valve train can satisfy the switch frequency demand of APV.