Electromagnetic valve fault principle

I. Introduction Electromagnetic reversing valve is short for electromagnetic valve. It is a component composed of electric and hydraulic components. It sends out signals from various electrical system switches, time relay, travel switch, pressure relay and other electrical components to make the electromagnet move and push the valve core to move , To change the flow direction, so that the implementing agencies for the forward or reverse movement; or for communication or cut off a certain oil, the hydraulic system unloading, boosting and so on. The specifications of electromagnetic reversing valve are divided into: ① according to the spool can be moved to the working position divided into: two, three, multiple; ② according to the control of the oil pass points are: two, three, Four-way, five-way, multi-pass; ③ according to the spool in the middle of the position of the control of the communication port (ie, the central spool valve function) points: O, H, Y, C, N type; ④ divided by the flow of medium and low pressure, medium and high pressure Second, the solenoid valve fault analysis (A) burning electromagnet (AC) ① magnet coil enameled wire does not use the required insulating paint, due to poor insulation and make the coil Burn out. ② Insulation paint flaking or coil buildup, the coil lead plastic wrap aging, resulting in leakage short circuit, or other aspects of the quality of the electromagnet and burn the coil. ③ Ambient temperature is too high: direct sunlight, oil temperature, room temperature is too high, poor ventilation and other causes of the aging coil. Electromagnet temperature should not exceed +50 ℃, not lower than -30 ℃. ④ environmental water vapor, water droplets, corrosive gases infiltrated into the electromagnet, causing damage to the coil damp rust and burn out. ⑤ improper selection of hydraulic fluid, viscosity is too high, viscous resistance, over the load range of the electromagnet overload and burn out. ⑥ electromagnet commutation frequency too fast, burn out the electromagnet. ⑦ solenoid valve assembly cleaning is not clean. (B) AC electromagnet suction is not enough, no action (C) the electromagnetic reversing valve is not reliable reversing valve commutation reliability Fault performance: ① no commutation; ② commutation direction commutation speed inconsistent; ③ stay for a period of time, send the message is not reset. Affect the reliability of the solenoid valve is mainly constrained by three forces: ① electromagnet suction; ② spring force; ③ spool of the friction (including viscous friction and hydraulic power). The commutation reliability is the most basic performance of the directional control valve. To ensure reliable commutation, the spring force should be greater than the frictional resistance of the valve core to ensure reliable reset. The electromagnetic force should be greater than the spring force and spool friction resistance between the two, in order to ensure reliable transposition. Therefore, from the analysis of the factors that affect these three forces, it is possible to find out the reasons why the commutation is not reliable and how to eliminate it. (D) of the electromagnetic valve leakage ① between the solenoid and valve body surface; ② solenoid valve body and the installation of the floor or the interface between the integrated block; ③ process plug and process valve head oil spill. (E) large internal leakage Large amount of leakage, resulting in power loss caused by the system temperature, or even abnormal movements. ① spool and valve hole with a large gap, or due to wear and gap; ② spool or valve hole shoulder size, sinking slot from the wrong size or tolerance, or oil seal shoulder gap, so that oil seal The length of the cover to reduce, resulting in increased internal leakage; ③ Balanced slot position size is set unreasonably, will shorten the oil seal length; ④ spool outer surface or the inner surface of the valve hole with axial groove; ⑤ oil temperature High; ⑥ spool and valve bore eccentric due to burrs; construction training in Anhui ⑦ shrinkage shrinkage valve and other casting defects. (F) pressure loss Large flow through the valve before the valve after the pressure difference, known as the valve pressure loss. Large pressure loss, resulting in oil temperature rise fever.