张耀1，滕勤1，张晓松1，李杰2

(1.合肥工业大学 机械与汽车工程学院,安徽 合肥 230009;2.安徽江淮汽车股份有限公司 技术中心, 安徽 合肥 230601)

    摘要：当代汽油机普遍配置了双顶置凸轮轴(DOHC)的可变气门正时(VVT)系统,发动机工作时配气机构对凸轮轴产生的负载扭矩会影响VVT相位器的调节速度。本文通过分析凸轮轴的受力状况,建立了凸轮轴负载扭矩的数学模型,基于Matlab/Simulink的仿真计算,确定了凸轮轴负载扭矩随转速的变化规律。针对发动机低速时凸轮轴负载扭矩对相位器调节的阻碍作用,开发了虚拟止回控制策略,基于凸轮轴负载扭矩正、负切换的基准角和机油流量特性,确定占空比切换时刻和虚拟止回占空比数值。目标相位提前和滞后的仿真结果表明,设定值从5°CA到45°CA和从45°CA到5°CA阶跃变化时,相位器调节速率分别提高25%和34%。

    关键词：双顶置凸轮轴;可变气门正时;凸轮轴负载扭矩;虚拟止回

Abstract：The contemporary gasoline engines are generally configured with variable valve timing (VVT) system with double overhead camshaft (DOHC). The phaser adjustment speed was affected by a camshaft load torque generated from the valve train during the operation of engine. In this paper, a mathematical model of the camshaft load torque is established through analyzing the force on camshaft, and the simulation and calculation are performed in Matlab/Simulink environment to determine the camshaft load torque changing law with the rotational speed. Aimed at the block effects on the phaser adjustment at low engine speed, a virtual check valve(VCV) control strategy is developed based on the switch angle of camshaft zero load torque and the oil flow characteristic, and the switch event crank angle positions and duty cycle of VCV is determined. The simulation results of target phase in advance or retard situation show that phaser adjustment rate is increased by 25% with setting value step changing from 5°CA to 45°CA or by 34% on the contrary.

    Key words：Double Overhead Camshaft；Variable Valve Timing；Camshaft Load Torque；Virtual Check Valve