| 摘要 |
PROBLEM TO BE SOLVED: To provide a filter element having a prefilter reduced in cost by simplifying a means mounting the prefilter to a main filter and excellent in external appearance since the component of the mounting means is not exposed on the surface of the perfilter. SOLUTION: The main filter 6 is formed by bending a filter material 2 such as filter paper and nonwoven fabric in a form like bellows and fixing a resin made substrate frame 3, an end surface frame 4 and an intermediate frame 5 projecting to an upper surface of the filter material 2 (the end surface frame 4 and the intermediate frame 5 project by about 2-3 mm upward from the upper surface of the filter material 2), and the prefilter 7 is mounted on the upstream side from the main filter 6, and a part of the end surface frame 4 or the intermediate frame 5 and the prefilter 7 are molten and solidified to fix both together giving an ultrasonic wave at an upper part corresponding to a position provided with the end surface frame 4 or the intermediate frame 5.
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