| 摘要 |
PURPOSE:To provide a device having a small pressure loss and filters of long life by disposing two filters carrying different numbers of chevron-shaped foldings and different areas when spread and placing on the inlet side a filter carrying more folding and larger area when spread. CONSTITUTION:A first filter element 4 and a second filter element 5 are disposed in a manner to be partitioned up and down almost in the center of a case 1 between a suction inlet 2 and a suction outlet 3. The first and second filter elements 4 and 5 have a number of chevron-shaped foldings 8, 8... and 9, 9... respectively, and the areas of suction flow direction are formed almost equally. The second filter element 5 carries a smaller number of chevron-shaped foldings and a smaller area when spread than those of the first filter element 4.
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