ROOTS PUMP PREVENTED FROM ACCUMULATING REACTION PRODUCTS

摘要

PURPOSE: A roots pump prevented from accumulating reaction products is provided to operate the roots pump without stoppage in a nitride film manufacturing process. CONSTITUTION: A housing forms pump chambers(17-21) inside. Plural rotary shafts(22) are supported on the housing in parallel with each other. Rotors(28-32) are mounted on each rotary shaft, and the rotators mounted on the adjacent rotary shafts are engaged with each other. The pair of engaged rotors are contained in the pump chambers. A confluence path(49) is formed along one cross line of a pair of virtual swept peripheral surfaces corresponding to the pair of engaged rotors one-to-one. Hermetic spaces are formed between the pair of peripheral surfaces and the pair of engaged rotors corresponding to the pair of engaged rotors one-to-one. The hermetic spaces join the confluence path from an end of the confluence path by rotation of the pair of engaged rotors.