| 摘要 |
PROBLEM TO BE SOLVED: To improve a structure not applying an internal compression system, which is the biggest concern in a conventional Roots-type rotary machine, to reduce the operating noise and pulsation, and to reduce the power. SOLUTION: A casing is not provided with a discharge port, a mountain- shaped projection is formed on a position of a conventional discharge port, and a discharge hole is formed on a side cover to form an internal compression structure, and further a double sound insulation shroud is mounted in the casing discharging direction. Whereby the back-flow of the discharged pressure into the casing is reduced, the pulsation is remarkably reduced, and the pulsation noise is reduced. The volume efficiency is improved, whereby the power is reduced. The noise is hardly leaked from a machine body to the external, whereby the noise is totally reduced. COPYRIGHT: (C)2003,JPO
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