The fault diagnosis method of excavator hydraulic pump can be classified into instrument diagnosis method and manual diagnosis method. The instrument diagnosis method is a physical test method. The manual diagnosis method uses vision, touch, smell and hearing to initially diagnose the technical status and faults of the hydraulic pump. Here are some commonly used instrument test diagnostic methods:
1. Rapid oil quality analysis
The basic principle of rapid oil quality analysis is to reflect the aging degree of the used oil by the change of the comprehensive dielectric constant. The rapid oil quality analyzer not only provides a quick and simple oil quality detection method for the hydraulic system of construction machinery, etc., but also can regularly monitor the running status of the equipment through the regular inspection of the oil in use to prevent accidents. It has changed the traditional regular oil change method in equipment management, and realized scientific oil change according to quality. This method can quickly detect various physical and chemical performance indicators of hydraulic oil on the spot to determine whether the failure of the hydraulic pump is caused by the deterioration of hydraulic oil.
2. Hydraulic system tester
Because the pressure of the hydraulic pump of the excavator remains unchanged within the adjustment range, it can be judged by the actual measurement of the flow of the hydraulic pump by the hydraulic system tester. The hydraulic tester is usually composed of a pressure gauge, a flow meter, a tachometer, etc. According to the connection method of the tester in the pipeline, it can be divided into a through test method and a bypass test method. Install the tester on the high-pressure pipeline of the oil pump by bypass method to make the oil pump run at the rated speed, the hydraulic oil temperature is about 60 ℃, observe and record the flow reading of the tester when it is not loaded, and then load it with the loading valve The load pressure gradually increases to the rated pressure of the system. Observe and record the flow reading at this time. If the measured flow rate drops by 25% compared with no-load, it indicates that the hydraulic pump has failed; if the flow reading decreases by 50%, it can be determined that the failure of the hydraulic system is caused by the hydraulic pump, and must be disassembled for excavator repair.
3. Noise meter
The normal noise limit value of the hydraulic pump of the excavator is 105db. If this limit value is exceeded, it may be caused by the concentricity of the motor and the pump drive shaft. It may also be that the air enters the inside or the hydraulic pump wears too much.
4. Thermometer
Diagnose the fault by testing the difference between the temperature of the hydraulic pump casing of the excavator and the temperature of the hydraulic oil.
If the temperature of the pump casing is higher than the oil temperature by more than 5℃, the mechanical efficiency of the hydraulic pump may be too low and the mechanical wear is large; if the temperature difference is above 10℃ and there is no problem with the system pressure setting, and the oil quality is no problem, it may be the shaft Large clearance, severe wear of hydraulic pump, reduced volumetric efficiency, and increased leakage.
5. Pressure gauge
Because the hydraulic pump of the excavator adopts constant pressure control, the pressure of the hydraulic pump system of the excavator does not indicate the working condition of the hydraulic pump, but the oil pump failure can be judged by the swing of the pointer of the pressure gauge. If the deflection of the pressure gauge pointer exceeds ±200kpa or the oscillation is very slow, it is an abnormal phenomenon.
