| 摘要 |
PROBLEM TO BE SOLVED: To provide a roots pump capable of reducing a leakage amount of fluid from a discharge port side to a suction port side without reducing a transferring amount of a fluid. SOLUTION: A first cross part 40 and a second cross part 41 are formed in a peripheral wall 13a in response to a position in which passing circumferential surfaces C1, C2 of a pair of rotors 27, 28 meshing each other cross each other. A pair of suction ports 31a, 31b are respectively provided to a position which is placed on the outside of a cross region U and is sandwiched between a cross circumferential surface K and respective passing circumferential surfaces C1, C2 in an end wall 13b, and to a position which is closed by end surfaces of the rotors 27, 28 when peak ends T1, T2 of respective rotors 27, 28 are positioned in the first cross part 40. A pair of discharge ports 32a, 32b are respectively provided to a position which is placed on the outside of the cross region U and is sandwiched between the cross circumferential surface K and respective passing circumferential surfaces C1, C2 in an end wall 13b and to a position which is closed by the end surfaces of the rotors 27, 28 when peak ends T1, T2 of respective rotors 27, 28 are positioned in the second cross part 41. COPYRIGHT: (C)2007,JPO&INPIT
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