Created on:2021-12-30 10:08

Diagnosis of hydraulic faults by function tracking screening method

Diagnosis of hydraulic faults by function tracking screening method

Function tracking screening method, also known as hydraulic fault reverse analysis method, refers to the analysis method of analyzing various influencing factors of hydraulic fault according to the relevant links of hydraulic function from the fault characterization of hydraulic system. In short, it is a method to analyze the cause from the result of hydraulic failure. This method is one of the most suitable methods for analyzing and diagnosing hydraulic faults. Its purpose is clear. As long as the relationship between hydraulic function and principle is clear, it is easy to find hydraulic fault. It is a widely used method in the practical application of hydraulic fault diagnosis.

1. Conditions for using function tracking screening method to diagnose hydraulic fault

(1) Master theoretical knowledge. Mastering the basic knowledge of hydraulic transmission is the prerequisite for diagnosing hydraulic system faults. Only by understanding the working principle can we correctly judge the hydraulic fault. Otherwise, troubleshooting will have a certain blindness. Mastering the common faults of hydraulic system can narrow the diagnosis scope and quickly cut the key of the problem. There are 7 common faults in hydraulic system: faults caused by hydraulic impact; Cavitation and cavitation failure; Hydraulic clamping failure; Temperature rise fault; Actuator crawling fault; Vibration and noise fault of hydraulic system; Hydraulic system leakage fault.

(2) Practical experience. In the hydraulic system, each hydraulic element works in a closed oil circuit, and the flow state of oil in the pipeline and the action of parts inside the element can not be seen or touched. Therefore, the fault diagnosis of hydraulic system is more difficult than that of general mechanical and electrical equipment. At the same time, the fault manifestations of hydraulic system are various and the laws are different. Therefore, to judge and eliminate these faults, we should not only have professional theoretical knowledge and master the functions, structures and principles of various hydraulic components and basic hydraulic circuits, but also have rich practical experience in design, manufacturing, installation, use, maintenance and maintenance.

(3) Master the working principle of specific system. The most important thing in diagnosing and troubleshooting is to be familiar with and master the working principle of the system. Each element in the system has its function. You must be familiar with the structure and working characteristics of each element. Before fault diagnosis, it is necessary to understand the capacity and working pressure of the system, understand the use of equipment and conduct on-site observation. Then, make a comprehensive analysis of the understanding, think carefully, and then carry out fault diagnosis and troubleshooting.

2. Fault diagnosis steps

The failure of the hydraulic system is caused by the failure of a component in the system. The fault diagnosis of hydraulic system is to find out the faulty hydraulic components. Figure B lists the analysis steps for diagnosing hydraulic faults by function tracking screening method.

The first step; Hydraulic system fault can be divided into five aspects: flow fault, pressure fault, direction fault, general mechanical fault and electrical fault.

Step 2: review the schematic diagram and installation layout of the hydraulic system. Understand the service life, service environment, maintenance and previous maintenance of the hydraulic system, check each hydraulic element, confirm its performance and function, and preliminarily evaluate its quality.

Step 3: list the components related to the fault and analyze them one by one. In this step, first, make full use of judgment, and second, pay attention not to omit components that have a significant impact on the fault.

Step 4; The components listed in the list shall be arranged according to previous experience and the difficulty of component inspection. If necessary, list the key inspection components and key inspection parts of components, and prepare measuring instruments, etc.

Step 5: conduct preliminary inspection on the key inspection components listed in the list. The following problems should be judged in the initial inspection: whether the use and assembly of components are appropriate; Whether the measuring devices, instruments and test methods of components are appropriate; Whether the external signal of the element is appropriate; Response to external signals, etc. Pay special attention to the fault precursors of some components, such as excessive temperature, noise, vibration and leakage.

Step 6: if the initial inspection fails to accurately find out the fault, special detection and test equipment and instruments shall be used for inspection.

Step 7: repair or replace the faulty components.

Step 8: before restarting the system, you must carefully consider the cause and result of this failure. For example, if the fault is caused by pollution and high oil temperature, it should be expected that other components may also fail, and corresponding remedial measures should be taken for hidden dangers. If iron filings enter the pump and cause pump failure, the system shall be thoroughly cleaned before replacing the pump.

Through long-term practice, it is proved that using function tracking screening method is an effective method in diagnosing simple hydraulic system faults. It can make people take fewer detours and find out faults quickly and accurately, so as to improve production efficiency, reduce production cost and create good economic benefits.

Home    Article    Diagnosis of hydraulic faults by function tracking screening method