The transmission and actuator of the excavator adopt hydraulic technology. The condition of the hydraulic system directly affects or even determines the operating condition of mechanical equipment. Therefore, fault diagnosis of the hydraulic system has extremely important meaning and effect on the condition of the excavator.
Diagnosis of hydraulic system belongs to the category of mechanical diagnosis. Many mechanical diagnosis methods can be directly applied to the fault diagnosis of the hydraulic system. The diagnosis method is based on the traditional diagnosis technology based on the maintenance staff's senses, personal experience and simple instruments, and then combined with the emerging sensor technology to collect data for analysis.
1. Method of direct performance test
Direct performance test method is to evaluate the working condition of hydraulic system through the performance test of hydraulic components and hydraulic system. And analyze the fault. The basic idea is that under normal circumstances the performance measurement values of the hydraulic components and systems being tested should vary within the normal range. When this range is exceeded, it can be considered that a failure has occurred or is about to occur. In the testing of hydraulic components and system performance, common measurements include pressure, flow, temperature, leakage and other corresponding types of parameters. The method is simple in principle and intuitive in concept. Performance testing is not very sensitive to early failure. Only when the system failure develops into a very serious one is its performance index reflected.
2. Analysis method based on vibration and noise
Vibration and noise are inevitable phenomena that accompany the hydraulic system during operation. Especially for the hydraulic pump, the vibration of its casing is very obvious. The vibration and noise signals of the device contain a lot of fault information. Through the analysis of the signal, you can get a lot of information about the status of the component, which helps to determine the working status of the device and thus effectively diagnose the fault.
3. Diagnosis method based on fault tree
The method of fault tree analysis is to draw a system fault and various factors that lead to the fault into a fault map. Intuitively reflects the interrelationships between faulty components, systems and causes. It is a more effective fault diagnosis method commonly used in actual work. The diagnosis process starts from the final fault of the system, by constructing an inverted fault tree step by step, and through heuristic search to find the final cause of the fault.
In the process of searching the fault tree, the traditional method is to determine the sequence according to the probability of the occurrence of the event. However, this is unrealistic in the diagnosis of actual hydraulic system faults. Due to the difficulty and cost of "hypothesis-verification" testing of different hydraulic components, the amount of information after testing is also different, so the order of events is determined Not only should we consider the probability of failure. Also consider the cost of testing and the amount of information.
to sum up
Daily maintenance of the excavator is a prerequisite to ensure the normal operation of the excavator, so it must be paid attention to.
In daily work, when analyzing the faults of the hydraulic system, it should first be decomposed by function. When solving the faults of the hydraulic system of the excavator, the faults of the electrical system should be ruled out first, and the parameters of the display screen should be ruled out. It is necessary to measure in person when necessary, which can speed up the process of fault diagnosis. Simultaneous qualitative and quantitative analysis of faults is conducive to improving diagnosis efficiency and accuracy.
