Hydraulic technology is used in the transmission and actuator of excavator. The condition of hydraulic system directly affects or even determines the operation condition of mechanical equipment. Therefore, the fault diagnosis of hydraulic system is of great significance and function to the machine condition of excavator.
The diagnosis of hydraulic system belongs to the category of mechanical diagnosis. Many mechanical diagnosis methods can be directly applied to the fault diagnosis of hydraulic system. The diagnosis method is based on the traditional diagnosis technology based on the senses, personal experience and simple instruments of maintenance personnel, and then combined with the emerging sensor technology to collect data for analysis.
1. Method of direct performance test
The method of direct performance test is to evaluate the working condition of hydraulic system by testing the performance of hydraulic components and hydraulic system. And analyze the fault. The basic idea is that under normal circumstances, the performance measurement values of the tested hydraulic components and systems should change within the normal range. When this range is exceeded, it can be considered that a fault has occurred or will occur. In the performance test of hydraulic components and systems, common measurements include pressure, flow, temperature, leakage and other corresponding types of parameters. The principle of this method is simple and the concept is intuitive. Performance testing is not very sensitive to early failure. Only when the system failure becomes very serious can its performance index be reflected.
2. Analysis method based on vibration and noise
Vibration and noise are inevitable phenomena in the operation of hydraulic system. Especially for the hydraulic pump, the shell vibration is very obvious. The vibration and noise signals of the equipment contain a lot of fault information. Through the analysis of the signal, we can get a lot of information about the condition of components, which is helpful to determine the working state of the equipment, so as to carry out fault diagnosis effectively.
3. Fault tree based diagnosis method
The fault tree analysis method is to draw the system fault and various factors leading to the fault into a fault diagram. Intuitively reflect the relationship between fault components, systems and causes. It is an effective fault diagnosis method commonly used in practical work. The diagnosis process starts from the final fault of the system, constructs an inverted fault tree step by step, and finds the final cause of the fault through heuristic search.
In the process of searching the fault tree, the traditional method is to determine the sequence according to the occurrence probability of events. However, this is unrealistic in the actual fault diagnosis of hydraulic system. Due to the different difficulty and cost of "hypothesis verification" detection of different hydraulic components, the amount of information after detection is also different. Therefore, when determining the sequence of events, we should not only consider the probability of fault occurrence. We should also consider the detection cost and the amount of information.
summary
The daily maintenance of the excavator is the premise to ensure the normal operation of the excavator, so we must pay attention to it.
In daily work, when analyzing the fault of the hydraulic system, it should be decomposed by function first. When solving the fault of the excavator hydraulic system, it should also first eliminate the fault of the electrical system itself and the misleading parameters of the display screen. It is necessary to measure in person, which can speed up the process of fault diagnosis. Qualitative and quantitative analysis of faults at the same time is helpful to improve the diagnosis efficiency and accuracy.
