汽车发动机热式空气质量传感器的动态特性

Dynamic Characteristics of Thermal Mass Air Flow Sensor for Automobile Engine

采用非线性建模方法研究了发动机热式空气质量流量(MAF)传感器的动态特性。基于静、动态标定数据,用两步辨识法建立了传感器的Hammerstein模型。建立多幅值激励下的模型时,充分考虑了激励信号源的延迟特性,并采用3种不同的方法对传感器的实际输入进行了估计。利用建立的模型分别计算了热线式和热膜式MAF传感器的时域和频域性能指标,并进行了分析和比较。结果表明,MAF传感器的动态响应特性与激励信号的大小有关,在发动机瞬态空燃比控制策略中应该采取措施补偿由于传感器变延迟特性引起的动态测量误差。

The dynamic characteristics of a thermal mass air flow （MAF） sensor for engine are studied using nonlinear modeling method. Based on static state and dynamic state calibration experiment data, the Hammerstein model is established by a two - step identification method. During modeling under multi- magnitude excitation, the delay characteristics of the excitation signal source was considered sufficiently, and the actual inputs acting on the sensor were estimated with three kinds of different methods. In terms of the established models, the time domain and frequency domain performance indices of the hot wire type and the hot film type MAF sensors were calculated and analyzed, respectively. Results show that the dynamic response characteristics of the MAF sensors are related to magnitudes of excitation signal, and that some schemes for the engine transient air fuel ratio control strategies should be adopted to compensate for dynamic measurement errors resulting from the sensor＇ s variable delay behaviors.