Patent ID: 6764288
Filing Date: 2004-07-20
Classification: F04C

Abstract:
Vacuum pumping apparatus comprising:a scroll set having an inlet and an outlet, said scroll set comprising a first stationary scroll blade and a second stationary scroll blade extending from a stationary plate and separated by a gap, and an orbiting scroll blade extending from an orbiting plate, wherein said first and second stationary scroll blades are intermeshed with said orbiting scroll blade to define one or more interblade pockets; a relief port in the gap between the first and second stationary scroll blades and coupled through a relief passage to an exhaust; a relief valve in the relief passage; and a drive mechanism operatively coupled to said orbiting plate for producing orbiting motion of said orbiting scroll blade relative to said first and second stationary scroll blades so as to cause the one or more interblade pockets to move toward the outlet.