Engine camshaft bearing loose failure diagnosis method and system

Abstract

The invention relates to an engine camshaft bearing loose failure diagnosis method and an engine camshaft bearing loose failure diagnosis system. The engine camshaft bearing loose failure diagnosis method comprises the steps of: acquiring an engine inertia parameter and an engine suspension system parameter; acquiring a vibration signal of an engine in a steady-state condition; analyzing frequency domain characteristics of the vibration signal; and calculating a center-of-mass generalized force of the engine according to the engine inertia parameter, the engine suspension system parameter and the frequency domain characteristics of the vibration signal, and diagnosing a engine camshaft bearing loose failure according to characteristics of the center-of-mass generalized force.

Description

technical field [0001] The invention belongs to the technical field of mechanical equipment fault diagnosis and signal processing, and relates to a method and system for diagnosing a loose fault of an engine camshaft bearing. Background technique [0002] The vibration analysis method is to measure the vibration signal of the cylinder head or cylinder block during the working process of the engine, analyze and process it to extract the fault characteristics, obtain the characteristic parameters of the vibration signal, and diagnose the fault of the engine according to the change rule of the characteristic parameters. [0003] In 1996, on the basis of experiments, F.Gu and A.D.Ball of the University of Manchester in the United Kingdom concluded that the vibration of the diesel injector was mainly caused by the needle valve opening, the impact of the seat and the high-pressure fuel flow. The vibration sensor is adsorbed on the top or the seat, the vibration signal is collected...

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Problems solved by technology

[0005] However, as a fault diagnosis method based on response signals, it is greatly affected by external conditions such as engine structure, environment, temperature, and the installation position of sensors. It can only be effective for specific engines, a small number of components, and fault types. universality

In 2013, Wang Guobiao pointed out that although single-fault diagnosis is usually easy to implement, when it is popularized and used, its accuracy is not high, its generalization ability is not strong, and its versatility is poor, which restricts its application in engineering

In addition, it was suggested that the cylinder pressure signal can be used for valve clearance monitoring and fault diagnosis. The scale signal decomposed from the binary wavelet of the cylinder pressure signal contains a large amount of state information of the valve clearance. There are certain difficulties in this aspect, and for some mechanical failures not related to combustion, the type and location of the failure cannot be determined from the pressure signal in the cylinder

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