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1. Composition and working principle
It is understood that the scraper system of this type of paver machine adopts a new structure and layout, which is mainly composed of hydraulic oil tank, scraper pump, electromagnetic overflow valve group, scraper motor, hydraulic oil filter, etc. The scraper pump adopts P R R-022/022L gear pump, and the scraper motor model is OMTS315. The model of electromagnetic overflow valve group is 98301113DWG/03, which is composed of two normally open cartridge overflow valves and one two-position two-way solenoid valve. The cartridge overflow valve model is SV4-8-O-0-24DGS. Two plug-in overflow valves are used to control the left scraper and the right scraper respectively. When the electromagnet Y26 is not energized, the pressure oil pumped by the hydraulic pump returns to the hydraulic oil tank; When electromagnet Y26 is powered on, the pressure oil path of the return tank is cut off, and the scraper motor works.
2. Troubleshooting
Check the road paver machine electrical system and find no abnormality. Check that the hydraulic oil is clear and free of pollution, and the hydraulic oil temperature is within the normal range. Check that the hydraulic oil pipeline is smooth and the hydraulic oil radiator works normally. After disassembling and inspecting the electromagnetic overflow valve group, it was found that the valve core was normal without impurities, the spring pressure was also normal, and the valve core switch was flexible. Replace the electromagnetic overflow valve group assembly with a new one on site, and the fault is still not eliminated, which can eliminate the possibility that the electromagnetic overflow valve group has a fault.
Through communication with the user, it was learned that the new machine was normal when it was used, and the scraper rotation failure occurred after 260h of operation. In the initial stage, only one side of the scraper motor rotates, and only when there is little material in the hopper, it will rotate, and then gradually develop into that both sides of the scraper motor will rotate, and more material will also rotate. Therefore, when electromagnet Y26 is powered on, some pressure oil may still return to the oil tank through the motor, causing the motor to rotate.
In order to further verify the judgment, connect a pressure gauge at the oil inlet of the scraper motor and test the pressure at the place of 0.4MPa, which shows that there is indeed some pressure oil flowing through the scraper motor. With the consent of the technical department, install a check valve with an opening pressure of 0.5MPa on the oil outlet pipe of the scraper motor and then test the running track paver machine. The paver fault disappears. After nearly 800h of test, the fault did not occur again.
3. Fault cause analysis
The analysis shows that when the electromagnet Y26 is powered off, all the pressure oil pumped by the scraper pump should flow back to the hydraulic oil tank through the electromagnetic overflow valve group. The opening of the solenoid overflow valve matches the displacement of the scraper pump. It may be that the opening of the solenoid overflow valve group valve is too small, resulting in residual oil pressure passing through the scraper motor when the solenoid Y26 running track paver machine is powered off.
At the initial use of the new equipment, the mechanical transmission components of the scraper system of the paver are new parts and are in the running-in period. The mechanical resistance is large, and the residual oil pressure cannot drive the scraper motor to run. With the extension of service time, the scraper drive device keeps running in, and its mechanical resistance gradually decreases and tends to be stable. When the mechanical resistance of the scraper system decreases to a certain extent, the scraper motor starts to rotate automatically. The above analysis is consistent with the fact that in actual work, less material will start to rotate and more material will also rotate.
A check valve with opening pressure is installed on the oil outlet pipe of the scraper motor to eliminate the influence of residual oil pressure on the motor and eliminate the fault.