1. Mechanical impurities in the oil or dirt, asphalt, carbon residue and other dirt precipitated by oxidation are accumulated in the throttle gap.
2. As the oil ages or is squeezed to produce charged polarized molecules, and there is a potential difference on the metal surface of the throttling gap, the polarized molecules are adsorbed to the surface of the gap to form a strong boundary adsorption layer, the thickness of the adsorption layer It is generally 5-8 microns, which affects the size of the throttle gap. When the above accumulated and adsorbed substances grow to a certain thickness, they will be washed away by the liquid flow and then reattached to the valve port. This repeats itself, forming a flow pulsation.
3. When the valve port pressure difference is large, due to the high temperature of the valve port, the degree of squeezing of the liquid is enhanced, and the metal surface is more susceptible to friction to form a potential difference, so when the pressure difference is large, clogging is easy to occur.