1, the mechanical impurities in the oil or due to oxidation of colloid precipitation, asphalt, carbon residue and other dirt accumulation in the throttle gap.
2, the oil aging or squeezed to produce charged polar molecules, and throttle gap on the metal surface potential difference, so the polar molecules are adsorbed to the surface of the gap, the formation of a solid boundary adsorption layer, the adsorption layer thickness Generally 5 to 8 microns, thus affecting the throttling gap size. Above the accumulation of adsorbate growth to a certain thickness, will be washed out of liquid flow, and then re-attached to the valve port. This cycle, on the formation of the pulse flow.
3, the valve port pressure is large, due to the valve port temperature is high, the degree of compression by the liquid increased, the metal surface is also more susceptible to friction and the formation of potential difference, so the pressure is likely to cause clogging.