汽车发动机瞬时转速测量中的噪声分析及补偿方法

Noise Analysis and Compensation of Momentary Crankshaft Speed of Automotive Engines

对汽车发动机的瞬时转速信号中的量测噪声进行补偿。试验测量结果表明 ,由飞轮齿圈的齿形误差引起的噪声是瞬时转速信号中的主要噪声源 ,并且该噪声的幅值与发动机的平均转速成正比。由于这种噪声的频带与飞轮瞬时转速信号的频带可能重叠 ,因此采用传统的滤波等方法无法完全消除齿形误差引起的噪声。提出采用 2个传感器的补偿新方法 ,可将齿形误差引起的噪声从瞬时转速信号中消除。试验结果验证了该方法的可行性 ,为利用瞬时转速信号检测发动机失火提供了条件。

To achieve precise measurement of momentary crankshaft speed, the noise in the speed signal of an automotive engines is analyzed and compensated in this paper. The test results show that the noise generated by teeth tolerance of the flywheel start-ring is the main noise in the speed signal. The amplitude of that noise is proportional to engine speed and strongly influences the measurement accuracy under high-speed condition, thus it is necessary to eliminate. As the frequency band of the noise is overlap with the frequency band of momentary flywheel speed, it is less efficient to eliminate the noise with conventional signal processing methods such as filtering the data. A new compensation method, which utilizes two speed sensors to identify the noise, is presented in this paper. The experimental results verified the accuracy and feasibility of the denoise method to process the momentary speed signal for engine misfire detection.