| 摘要 |
PROBLEM TO BE SOLVED: To prevent the assembly property of a filter from worsening even if a packing is arranged in a filter insertion port part. SOLUTION: A tip of a frame body 132 of the filter 130 is displaced along an inclined face 123a formed at a tip of a protruding part 123 of an inner and outer air switching casing 121, and the frame body 132 is bent to fit the protruding part 123 into a hole part 133. Consequently, a secure and large fixing force can be obtained when compared with a friction force, and the protruding part 123 can be securely fitted into the hole part 133 by a comparatively small insertion force with proper sense of moderation. As a result, the assembly property of the filter 130 can be improved by pressing and crushing the packing 140 and sealing the insertion port 126 part securely.
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