The method for collecting contaminants in fluids is in many forms. The apparatus for trapping contaminants made of filter materials is called a filter. The magnetic material absorbs magnetic contaminants as a magnetic filter. In addition there are electrostatic filters, separation filters, etc. In the hydraulic system, all the contaminant particles in the collection fluid are collectively referred to as hydraulic filters.
The most widely used hydraulic filters currently used are porous filters or wound slits to intercept contaminants. Magnetic filters and electrostatic filters are also used in hydraulic systems.
The function of the hydraulic filter is to filter various impurities in the hydraulic system.
The main sources are: mechanical impurities that remain in the hydraulic system after cleaning, such as rust, cast sand, welding slag, iron filings, paint, paint and cotton swarf, etc., and impurities that enter the hydraulic system from the outside, such as through the filling port and The dust that enters the dust ring, etc.; Impurities produced during the working process, such as debris formed by the action of the seal on the seal, movement of metal powder produced by relative abrasion, gum, asphaltene, carbon residue, etc. resulting from oil degradation due to oxidation .
After the above impurities are mixed into the hydraulic oil, the hydraulic oil will be destroyed everywhere, which will seriously affect the normal operation of the hydraulic system, such as the small gap (in μm) and the joint between the relative moving parts in the hydraulic element. Flow holes and gaps jam or block; damage the oil film between the moving parts, scratch the surface of the gap, increase internal leakage, reduce efficiency, increase heat, exacerbate the chemical action of the oil, and degrade the oil. According to production statistics, more than 75% of the failures in the hydraulic system are caused by impurities in the hydraulic oil. Therefore, maintaining the cleanliness of the oil and preventing the contamination of the oil is very important for the hydraulic system.
The general hydraulic filter is mainly composed of a filter element (or strainer) and a housing (or skeleton). Numerous tiny gaps or small holes in the filter element constitute the flow area of the oil. Therefore, when the size of impurities mixed in the oil is larger than these small gaps or pores, it is blocked from being filtered out of the oil.
Because different hydraulic systems have different requirements, it is impossible to completely filter the impurities mixed into the oil, and sometimes it is not necessary to be exact.