Vacuum pumps with claw-type rotor and roots-type rotor near the outlet
AssigneeThe BOC Group, Inc.
InventorAlan Paul Troup
Life of this patent
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Abstract
A mechanical vacuum pump having mounted in each of at least three pumping chambers a pair of intermeshing rotors. A first rotor of each pair being mounted for rotation on a first shaft passing through the chambers and a second rotor of each pair being mounted for rotation on a second shaft passing through the chambers. The first and second shafts are driven in contra-rotating directions to effect a sequential pumping action by the pairs of rotors in each chamber in respect of gas being pumped between a pump inlet and a pump outlet. The pump possesses at least one chamber with claw-type profile rotors and one ore more chambers with roots-type profile rotors. The chamber nearest the pump outlet has a rotor with a roots-type profile.
Claims4
A mechanical vacuum pump comprising:
- a pump inlet;
- a pump outlet;
- at least three pumping chambers located between the pump inlet and outlet;
- at least three pairs of intermeshing rotors mounted for rotation within said at least three pumping chambers;
- first and second shafts passing through said at least three pumping chambers, a first rotor of each of the at least three pairs of intermeshing rotors mounted on the first shaft and a second roto of each of said at least three pairs of intermeshing roters mounted on the second shaft;
- and
- means to drive the first and second shafts in contra-rotating directions to effect a sequential pumping action by the at least three pairs of intermeshing rotors in respect of gas being pumped between said pump inlet and outlet;
- at least one of the three pairs of intermeshing rotors having a claw-type profile and at least another of the at least three pairs of intermeshing rotors having a roots-type profile and being located within one of said at least three pumping chambers situated nearest the pump outlet.
Dependencies are inferred from the claim text.