Construction machinery accessories EHPR08-33 threaded cartridge valve

Proportional pressure valve failure analysis and elimination

The current flowing through the proportional electromagnet is too large, but the pressure is still not up, or the required pressure can not be checked at this time the coil resistance of the proportional electromagnet, if far less than the specified value, then the internal circuit of the electromagnet coil is broken; If the electromagnet coil resistance is normal, then the connection to the proportional amplifier is short-circuited. At this time, the proportional electromagnet should be replaced, and the connection should be connected, or the rewound coil should be installed.

When the pressure step changes, the pressure fluctuation of small amplitude is constant, and the reason for the instability of the set pressure is mainly that there is dirt attached between the core of the proportional electromagnet and the guiding part (guide sleeve), which hinders the movement of the core. In addition, the sliding part of the main spool is stuck with dirt, which hinders the movement of the main spool. Due to the effects of these filth, the hysteresis increases. In the scope of hysteresis, the pressure is unstable and the pressure fluctuates constantly. Another reason is that the wear of the iron core and the magnetic sleeve pair, the gap increases, and the adjusted pressure (through a certain current value) is unstable.

At this time, the valve and proportional electromagnet can be disassembled for cleaning, and the pollution of the hydraulic oil can be checked. If it exceeds the regulations, the oil should be changed; For excessive clearance caused by the wear of the iron core, resulting in the increase of force hysteresis, resulting in unstable pressure regulation, the outer diameter of the iron core should be increased to maintain a good fit with the guide sleeve.

The pressure response is sluggish and the pressure changes slowly because the air in the proportional electromagnet is not discharged clean; The fixed orifice and main valve orifice (or bypass orifice) for damping on the electromagnet core are blocked by dirt, and the movement of the proportional electromagnet core and main valve core is hindered unnecessarily; In addition, air is entered into the system, which usually occurs when the equipment has just been installed and started to operate or when the air is mixed after long-term shutdown.