【作者】 雷术彬；

【导师】 韩宗奇；

【作者基本信息】 燕山大学 ， 车辆工程， 2011， 硕士

【摘要】 发动机负荷率是影响汽车燃油经济性的重要因素。研究表明发动机在负荷率为80%~90%时,燃油经济性较好。发动机选配时一般是以保证汽车预期的最高车速、加速与爬坡能力为前提,而在市区行驶的轿车大多情况下是以中低速行驶,发动机负荷率低,通常为20%~50%,因此油耗较高。发动机变工作排量技术,根据汽车的实际工况,通过电控方式有规律的停止部分气缸作功,以改变发动机实际参与作功的排量,使发动机始终处于较经济的负荷率区间,从而提高汽车的燃油经济性。研究变排量技术,通过对具体的变排量模式下发动机输出功率及扭矩的预测,为变排量控制策略提供依据。本文采用Elbert Hendricks提出的发动机“平均值模型”与经验公式相结合的方法,通过对节气门开度、进气歧管容积、进气歧管内空气压力及温度、进气流量、喷油量和发动机转速等建模所需参数的研究,利用Matlab/Simulink模块建立了变排量发动机动力输出特性计算模型,为发动机变排量控制策略的制定提供了条件。最后进行了发动机台架试验,并对试验数据进行了曲线拟合,验证了计算模型的精度。结果表明所建立的模型计算误差较小,由于发动机的经济工作区间也非定值,因而能满足发动机变排量技术的要求。更多还原

【Abstract】 The engine load rate is an important factor of automobile fuel economy. Research achievements show that when the gasoline engine load rate is 80%~90%, fuel economy is better. When choosing engine for a car, we consider ensuring the excepting maximum speed and acceleration and climbing capacity as the precondition. Cars in urban area mostly driving in medium-low speed, the engine load rate is as low as 20%~50%, so the fuel consumption is higher. Variable displacement technique of engine regularly stops partial cylinders working to change the actual displacement according to the actual automobile working condition, this makes engine working in economic load rate all the while, so the automobile fuel economy is improved.By means of calculating the engine output power and torque under different variable displacement mode, providing rational basis for variable displacement control strategy. This paper uses empirical equation and‘mean value engine model’which is suggested by Elbert Hendricks, studied desired parameters during modeling such as throttle percentage, volume of intake manifold, pressure and temperature of intake air, air inflow, fuel delivery, engine speed and so on, built predicting model of variable displacement engine output characteristic by using Matlab/Simulink, provided precondition for drafting control strategy of engine variable displacement. Finally we verified the precision of the calculation model by curve fitting of engine test data. Test results show that the calculation model showed small errors, this can meet the requirements for the economic engine workspace is not a fixed value.更多还原