Comprehensive parameter checking device used for hydraulic fault diagnosis
1. the working principle of the detecting device
Hydraulic system uses a lot of diagnostic parameters, but the most commonly used functional indicators are: pressure P, flow Q, temperature T, speed n, torque M, speed V, force F and so on. The non functional indexes such as vibration, noise, acoustic emission, composition of oil and contamination of oil can also be used as diagnostic parameters, but the diagnostic parameters are n, M and V. The introduction of F and non functional parameters complicates the problem. Considering the diagnostic principle and portability of the detection device, the selected diagnostic parameters are p, Q, T. In addition, considering the other factors, the basic scheme of detection device is P, Q, T+ loader + safety protection device.
The detection principle as shown in Figure 6-12, here is the key to diagnosis flow detection device, it is for the diagnosis of practical, convenient and accurate effect, alternatives have advanced flow measurement method of turbine throttle, and without changing the original pipeline, such as laser, spectrometer ultrasonic flowmeter and heat transfer method. In the test device, the turbine detector, the strain sensor and the temperature sensor are composed of the turbine type flowmeter, the strain sensor and the temperature sensor. The population is added with filter screen to protect the flow juice. To prevent overload, an overload safety valve is provided in the diagnostic device, and a nylon shear pin safety valve is applied to the back pressure. The output of the detecting device can be analog or digital display.
2. typical mode of field fault diagnosis
The field or field operation, using a portable parameter detection device is convenient, quickly and accurately identify the location of the fault of hydraulic system the most basic is composed of hydraulic pump, relief valve, reversing valve and oil motor and other components. Although some hydraulic systems are slightly different, the diagnostic principles and procedures are basically the same.
(1) the bypass check diagnosis bypass diagnosis is called the short circuit inspection diagnosis, and the parameter detection device is connected in parallel in the system. It is a low back pressure field diagnosis method. The diagnosis of the oil pump is shown in figure 6-13a. The diagnosis of the overflow valve is shown in figure 6-l3b, and the diagnosis of the reversing valve is shown in figure 6-13b.
(2) through checking diagnostic parameter detection device in series system, is a kind of field diagnosis method of high back pressure, the basic idea and the diagnosis of low back pressure is similar to that of figure 6-14a, B, C shows. High back pressure testing device can withstand the pressure of the specified limit, so it can be connected into the system for diagnosis. The utility model has the advantages that the state of the diagnosis system can not be changed during the diagnosis, the real-time detection and diagnosis can be carried out, and the utility model can be used for the closed hydraulic system, and of course, the utility model can also be used for the diagnosis and diagnosis of low back pressure. But low back pressure testing device is very effective in detecting and diagnosing open system. In order to facilitate field diagnosis, in the hydraulic system design, the special T - shaped joint can be installed on the pipe in advance (Figure 6-15). Such as foreign crane, winch hydraulic system on the pipeline, the installation of special joints in advance for diagnostic use. In this way, the hydraulic component is not needed to be disassembled during the diagnosis and the downtime is shortened. This kind of diagnosis is carried out when the equipment is running normally. It is simple and fast. If a fault is diagnosed, the repair can be arranged at the proper time without interrupting production. It is suitable for hydraulic equipment preventive maintenance, accidents can prevent mechanical, can save a lot of manpower and cost, but also in peacetime can be the T joint magnetic plug third port plug, the magnetic plug can be another form of a fault diagnosis, can be sucked in the grinding block chip sampling head, spectrum and Ferrography analysis.
A comprehensive portable hydraulic fault diagnosis device is equivalent to a multimeter commonly used in electrical engineering. The diagnosis device is simple and reliable, and is especially suitable for wild night industry without power supply. This provides a very convenient and practical inspection appliance for the fault diagnosis of hydraulic. Judging from the field trial, the accuracy of the diagnosis system is 87%, and the effect is satisfactory.
