Separation Method of Impulsive Fault Component for Gasoline Engine Based on Acoustic Signal Analysis

Figure 5

Relationship between fault features at different phases. If ρ(D_W1k, D_W2k) increases with the number of superpositions until it is greater than threshold M₂, then the positional deviation can be ignored. ρ(D_W1k, D_W2k) is not strictly monotonous with the number of superpositions due to the influence of background noise, such as ρ(D_W13, D_W23) is less than ρ(D_W12, D_W22) and ρ(D_W16, D_W26) is less than ρ(D_W15, D_W25). Hence, ρ(D_W1k, D_W2k) is indirectly compared under the number of superpositions by using equation (4).