基于油耗和空燃比的汽油机充气效率测定方法

从充气效率的定义出发,提出了基于油耗和空燃比测量结果的汽油机充气效率测定方法。利用汽油机稳态工况下油耗量和空燃比计算得到相应的进气量,再根据定义直接计算充气效率。推导了基于油耗和空燃比的充气效率计算公式及误差分析公式。针对配备有ZH600发动机电控系统的ZS157FMI-3型发动机,先后设计了喷油器流量系数标定试验系统以及油耗和空燃比测试系统,通过测定平均油耗和瞬态油耗并结合空燃比测量对该型发动机的充气效率进行了测定。充气效率的测量结果表明,在同一试验条件下,采用两种油耗测试方法测得的充气效率差异很小;充气效率测试的误差分析结果表明,在本试验设备测量精度范围内,所得到的充气效率相对误差很小(基本在0.5%以下),具有很高的测量精度。此外,由于该充气效率测试方法克服了压力波法及流速-压力法的固有缺陷,在理论上的测量精度和对燃料种类的适应性方面,均具有明显的优越性。

Gasoline Engine Charge-efficiency Measuring Based on Fuel Consumption and AFR Test

This essay describes a new method, based on fuel consumption and AFR (Air-fuel ratio) measuring, to acquire the charge efficiency of internal combustion engine. In the method, the fuel consumption and AFR under steady condition are used to calculate the air inlet, and the air charge efficiency is calculated by definition. The equations of air charge efficiency and error analysis were built on fuel consumption and AFR. An injector flux calibration & testing system and a measuring system of fuel consumption and AFR were designed for a ZS157FMI-3 motor equipping with ZH600 engine electronic control system. The charge efficiency was tested through measuring mean and transient fuel consumptions and AFR. The efficiency test result indicates that the two methods of measuring fuel consumption have a good consistence for charge efficiency calculation, and the error estimation of the test results demonstrates that the efficiency results calculated from the fuel consumption and AFR have high accuracy, with the relative error below 0.5%. Since the charge efficiency acquiring way overcomes some inherent drawbacks of the common methods such as pressure wave method and velocity-pressure method, it offers more measure accurate in theory and better adaptability to different fuel types.