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

Figure 4

Relationship between fault features acquired at different phases. (a) Intercepting abnormal signals at different phases. (b) Intercepted results at θ_i and θ_i+1, where f(n) is the abnormal sound signal generated during engine operation, d_i denotes the length of the abnormal signal between phases θ_i and θ_i+1, B₁ represents the fault component intercepted at θ_i, B₂ refers to the fault component intercepted at the next θ_i, B₃ indicates the fault component intercepted at θ_i+1, and B₄ signifies the fault component intercepted at the next θ_i+1. In comparison with θ_i+1, θ_i is far from the position where the fault component exists, and a large positional deviation may occur between B₁ and B₂ acquired at θ_i in different q revolutions due to slight changes in the engine speed. θ_i+1 is close to the position where the fault component exists. If the deviation between B₃ and B₄ is small enough and can be regarded as a natural error, then the starting point can be selected at the position of θ_i+1.

(a)

(b)