What is a Hydraulic Filter?

The role of the hydraulic filter is to filter various impurities that appear in the hydraulic system. Its sources are mainly mechanical impurities remaining in the hydraulic system after cleaning, such as water rust, cast sand, welding slag, iron chips, paint, paint skin and cotton shavings, etc., external impurities entering the hydraulic system, such as dust entering through the refueling port and dust ring, etc.; impurities generated by the work process, such as seals formed by the hydraulic action of the debris, the movement of the metal powder generated by relative wear, the oil produced by oxidation and degradation of gum The hydraulic filter is a hydraulic component. Hydraulic filter belongs to the hydraulic parts.

Format

The method of collecting contaminants in fluids is in various forms, and the apparatus for trapping contaminants made of filter material is called a filter. Magnetic material to attract magnetic contaminants is called magnetic filters. In addition, there are electrostatic filters, separation filters, etc. In the hydraulic system, where the collection of contaminated particles in the fluid are generally called hydraulic filters. The most widely used hydraulic filters are magnetic filters and electrostatic filters used in hydraulic systems, in addition to the method of using porous materials or winding fine slits to intercept contaminants.

The above impurities mixed into the hydraulic fluid, with the hydraulic fluid cycle, will play a destructive role everywhere, seriously affecting the normal work of the hydraulic system, such as making a small gap between the relative moving parts in the hydraulic components (to count μm) and throttle holes and gaps stuck or blocked; destroy the oil film between the relative moving parts, scratch the surface of the gap, increase internal leakage, reduce efficiency, increase heat, intensify the fluid chemical action, so that the fluid deterioration. According to the production statistics, more than 75% of the failures in the hydraulic system are caused by impurities mixed in the hydraulic fluid, so it is important to maintain the cleanliness of the fluid and prevent the pollution of the fluid to the hydraulic system.

The general hydraulic filter is mainly composed of a filter element (or screen) and a housing (or skeleton). Therefore, when the size of the impurities mixed into the fluid is larger than these tiny gaps or holes, they are blocked and filtered out from the fluid. Since different hydraulic systems have different requirements, it is impossible to completely filter out the impurities mixed into the fluid, and sometimes it is not necessary to be demanding.

Accuracy Requirements

Technical requirements of hydraulic filter.

The filter material should have a certain mechanical strength to ensure that it will not be damaged by the action of liquid pressure under a certain working pressure.
Under a certain working temperature, it should maintain stable performance; have sufficient durability.
Have good anti-corrosion ability.
Structure as simple as possible, compact size.
Easy to clean and maintain, easy to replace the cartridge.
Low cost.

The Working Principle of Hydraulic Filter

Hydraulic oil enters the pipeline from the left to the filter, flows from the outer filter element to the inner core, and then flows out from the outlet. When the outer filter element is blocked, the pressure increases and reaches the opening pressure of the relief valve, the oil passes through the relief valve to the inner core and then flows out from the outlet, the outer filter element has higher precision than the inner filter element, and the inner filter element belongs to coarse filtration. Hydraulic filter experimental method: The international standard ISO4572 has been commonly used around the world to evaluate the "multiple pass method of hydraulic filter element filtration performance", the experimental content includes determining the filter element, the differential pressure characteristics of the clogging process and the scale capacity for different sizes of filtration ratio (βvalue). The multiple pass method simulates the actual working condition of the filter in the hydraulic system, where the contaminants continuously invade the system fluid and are continuously filtered out by the filter, while the particles that are not filtered out return to the tank and pass through the filter again.