| 摘要 |
PROBLEM TO BE SOLVED: To provide a dust cover structure surely preventing intrusion of dust to a space to be protected by a dust cover including a breather hole. SOLUTION: A dust guide member 171 having a roughly circular arc shape cross section is formed integrally at an inside of the breather hole 172 in the dust cover 107. A swirl chamber 173 is formed between the dust guide member 171 and an inner surface of the duct cover 107. The inside of the dust cover is divided to the swirl chamber 173 and a protection space 108 into which dust is prevented from intruding. When the dust cover inner space expands, air flowing in from the breather hole 172 is guided by the dust guide member 171 and swirl is generated in the swirl chamber 173. Dust flowing in together with air flows along the swirl and does not flow into the protection space 108, and is trapped in the swirl chamber 173. When the space in the dust cover contracts, the dust trapped in the swirl chamber 173 is discharged to the external by air discharged from the breather hole 172. COPYRIGHT: (C)2010,JPO&INPIT
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