| 摘要 |
PROBLEM TO BE SOLVED: To provide a suction port body suitably usable for each of cleaning with the quantity of circulating air set large and cleaning with the quantity of circulating air set small. SOLUTION: A suction port body main part 20a is provided with a vent part 24 for taking air inside from the outside, and an on-off valve 26 for opening/closing the vent part 24. The on-off valve 26 closes the vent part when the circulating air is a prescribed quantity or more, and opens the vent part 24 when the circulating air is less than the prescribed quantity. Negative pressure in the suction port body main part 20a is thereby heightened when the circulating air is the prescribed quantity or more, and the negative pressure in the suction port body main part 20a is lowered when the circulating air is less than the prescribed quantity. COPYRIGHT: (C)2004,JPO
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