基于最优阈值法的曲轴缺齿位置判定研究

Research on Position Identification of Missing Teeth of Crankshaft Based on Optimal Threshold Method

为了准确判定电控发动机上止点位置,建立了信号齿盘概率分布的数学模型,并根据最优阈值统计算法实现了对缺齿位置的判定。采集了某氢气电控发动机转速试验数据,并分析了试验结果,得到了不同转速下正常齿的方差分布,且当前瞬时转速与上个瞬时转速的速度比ncurrent/nlast的概率分布服从正态分布。采用最优阈值统计算法得到了最优阈值Tjudge的通用公式,并通过60-2、60-3和30-2三种正时齿盘方案验证了该通用公式的正确性。最后求出了缺齿出现误判时转速波动率的临界值,增加缺齿数对防止缺齿位置误判是十分有利的。

In order to identify the engine TDC position accurately, this paper establishes the probability distribution mathematical model of signal crankshaft flywheel an d realized position identification of missing teeth with optimal threshold metho d. The H2 IC engine experimental data is acquired and analyzed, the varia nce distribution of the normal teeth at different speed is calculated, and the probability distribution of the speed ratio between current and last speed ncurrent/nlast obeys normal distribution. The genera l expression of optimal threshold Tjudge for different signal cranksha ft flywheel is educed, and the correctness is validated by three different sig nal crankshaft flywheels, including 60-2, 60-3 and 30-2. The critical value o f speed fluctuation ratio, when error identifcation of missing teeth occurs, is obtained finally, the increasing missing teeth number is benefit for preventing e rror position identification of missing teeth.