Fuel filter element

Abstract

A fuel filter element (10) includes a first layer (11) and a second layer (12). The first layer (11) has a first pore size. The second layer (12) is stacked on the first layer (11) and has a second pore size smaller than the first pore size. The second layer (12) is a filter paper made of a fiber including a refined fiber (13) and an unrefined organic fiber (14). The refined fiber (13) is a cellulose fiber treated with a refining process and fibrillated so as to have a freeness within a range from 120 ml to 180 ml. The unrefined organic fiber has a fiber diameter within a range from 8 [mu]m to 13 [mu]m and is not treated with a refining process. The refined fiber accounts from 70 weight % to 85 weight % of the fiber and the unrefined organic fiber (14) accounts for the remain.

Description

technical field [0001] The invention relates to a fuel filter element comprising two layers with different pore sizes. Background technique [0002] US Patent 7137510 (corresponding to Japanese JP-T-2001-523562) discloses a filter element having two layers abutted together along the flow direction. [0003] The pore diameter of the layer arranged on the upstream side is larger than the pore diameter of the layer arranged on the downstream side, so the filtration accuracy is improved in the flow direction. That is, the layer arranged on the upstream side is a coarse layer, and the layer arranged on the downstream side is a dense layer, which is denser than the coarse layer. Along the flow direction, first, larger foreign matter is trapped by the coarse layer. Then, the small foreign matter passing through the coarse layer is captured by the dense layer. Therefore, the filter life can be extended while ensuring a predetermined filter efficiency. [0004] The dense layer is...

AI Technical Summary

Problems solved by technology

However, just increasing the mixing ratio will increase the pressure loss caused by the filter paper, and the flow resistance of the fluid may be particularly large

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