The paper filter is mainly composed of an aluminum filter, a shell stamped from a steel plate, and a paper filter element. The oil inlet on the filter cover communicates with the fuel delivery pump, the oil outlet communicates with the fuel injection pump, the return pipe joint is connected with the fuel injector oil pipe, and the cover is also equipped with a vent screw plug. A round bucket with many small holes is surrounded by a special filter paper folded, and both ends are glued and sealed with a cover plate. After the diesel oil enters the filter, it passes through the filter paper, collects in the filter element drum, and then passes through the oil outlet to the fuel injection pump. The impurities and moisture accumulated at the bottom of the shell are released from the oil drain plug at the bottom of the shell.
Purification method and working principle of filter element
(1) Screening effect
When the fluid passes through the porous body, the impurity particles of the particle size in the fluid are intercepted on the surface by the porous body; the particles with the diameter smaller than the porous body pass through the porous body with the fluid.
The sieving effect is the basic principle of the filter. General wire mesh filters and surface filters are filtered according to the sieving effect. Since the pore size of the filter material and the diameter of the impurity particles are not a complete circle, they are both equivalent pore size and equivalent particle size. Therefore, the particle size it intercepts is much smaller than the pore size of the filter material.
(2) Brownian motion
Brownian motion (the phenomenon in which suspended particles continue to move irregularly is called Brownian motion) and the aggregation of particles and the impurity particles in the adhering fluid make irregular Brownian motion all the time, when it moves to the pores of the porous body. When the wall is stuck, it stays in a small area on the hollow and is filtered out by the porous body.
Impurity particles may also collide with each other due to Brownian motion and liquid vibration. Under the action of surface binding force, the apparent diameter of the particles gradually increases. As we all know, the surface ability of particles increases with the decrease of particle size (inversely proportional relationship), and is proportional to the square root of the contact area between particles, so tiny particles are easy to aggregate and not easy to disperse.
3) Use the filter material to separate the “affinity” and “distance” effects of the media
When the oil stream with tiny water droplets enters a filter material that is “friendly” and “phobic” (such as a microporous filter paper with a resin content of 27 to 32%), due to the “affinity” of the filter material for oil , The oil flow can pass through the pores of the filter material smoothly; due to the “distance” performance of the filter material to water, tiny water droplets cannot pass through the pores of the filter material smoothly.
Due to the infiltration effect of the tiny water droplets on the fluff of the filter material, the tiny water droplets stay on the fluff of the filter material. The intercepted tiny water droplets gradually increase and gradually coalesce into large water droplets. Under the action of oil pressure, the water droplets are pressed to the wedge-shaped passage of the filter element, forming larger water droplets. Under the lease of oil pressure, after the water droplets pass through the filter material, under the effect of their own quality, the countryside settles and falls into the water collection cup.