Vacuum pump stators and vacuum pumps

Abstract

Combined booster and primary pump arrangements can be bulky and require separate supplies of purge gas and cooling water. In order to overcome this problem invention provides a vacuum pump in which two or more pumping mechanisms, i.e. the booster pump and main pump, are housed in the same stator. The invention further provides a vacuum pump stator comprising at least two operatively interconnected cavities, wherein at least two of the cavities each comprise at least one rotor-receiving portion shaped to receive two or more at least partially intermeshing rotors, and wherein an axis of a rotor-receiving portion of a first one of the cavities is offset with respect to an axis of a rotor-receiving portion of a second one of the cavities.

1 . A vacuum pump stator comprising at least two cavities, wherein at least first cavity of the at least two cavities and a second cavity of the at least two cavities each comprises a respective rotor-receiving portion shaped to receive at least one pair of intermeshing rotors, and wherein an axis of the respective rotor-receiving portion of the first cavities cavity is offset with respect to an axis of the respective rotor-receiving portion of the second cavity. 
     
     
         2 . The vacuum pump stator of  claim 1 , wherein the at least two cavities are operatively interconnected by a conduit. 
     
     
         3 . The vacuum pump stator of  claim 2 , wherein the conduit extends through a body of the vacuum pump stator to interconnect two cavities of the at least two cavities. 
     
     
         4 . The vacuum pump stator of any of  claim 1 ,  2  or  3 , wherein at least one cavity of the at least two cavities comprises a plurality of axially aligned, and interconnected, rotor-receiving portions. 
     
     
         5 . The vacuum pump stator of  claim 4 , wherein each of the plurality of axially aligned, and interconnected, rotor receiving portion is adapted, in use, to receive a pair of intermeshing rotors, a first rotor of each pair of intermeshing rotors being mounted on a first shaft and second rotor of each pair of intermeshing rotors being mounted on a second shaft, and wherein the plurality of axially aligned, and interconnected, rotor receiving portions of the at least one cavity are interconnected in series by interconnecting conduits such that each pair of intermeshing rotors and its corresponding rotor-receiving portion of the at least one cavity forms a separate pumping stage of a multi-stage vacuum pump. 
     
     
         6 . The vacuum pump stator of any of  claim 1 ,  2  or  3 , wherein at least one cavity of the at least two cavities comprises a single rotor-receiving portion adapted, in use, to receive a pair of intermeshing rotors, a first rotor of the pair of intermeshing rotors rotors being mounted on a first shaft and second rotor of the pair of intermeshing rotors being mounted on a second shaft, the pair of intermeshing rotors and the single rotor-receiving portion together forming a single pumping stage of a vacuum pump. 
     
     
         7 . The vacuum pump stator of  claim 1 , wherein, in use, the clearance between the vacuum pump stator and a rotor of the at least one pair of intermeshing rotors is sufficiently small to form an effective seal between the vacuum pump stator and the rotor. 
     
     
         8 . The vacuum pump stator of  claim 1 , wherein a rotor of the at least one pair of intermeshing rotors has a profile from any one or more of the group comprising: a Roots profile, a Northey profile, and screw profile. 
     
     
         9 . The vacuum pump stator of  claim 1 , further comprising a plurality of separable stator portions adapted to sealingly mate with one another. 
     
     
         10 . The vacuum pump stator of  claim 8 , wherein at least one of the plurality of separable stator portions comprises a recess forming, in use, at least part of one cavity of the at least two cavities. 
     
     
         11 . The vacuum pump stator of  claim 9 , wherein at least one of the separable stator portions comprises first and second recesses, the first and second recesses forming, in use, at least part of the first cavity and the second cavity, respectively. 
     
     
         12 . The vacuum pump stator of  claim 1 , further comprising a cooling circuit. 
     
     
         13 . The vacuum pump stator of  claim 11 , wherein the cooling circuit comprises a channel in the vacuum pump stator for conveying, in use, a flow of coolant fluid to cool the vacuum stator. 
     
     
         14 . The vacuum pump stator of  claim 12 , further comprising a plurality of separable stator portions adapted to sealingly mate with one another, wherein the cooling circuit channel comprises a plurality of cooling circuit channel portions arranged, in use, to align when the separable stator portions are assembled, to together form at least one continuous cooling circuit channel in the vacuum pump stator. 
     
     
         15 . The vacuum pump stator of  claim 12 , wherein the cooling circuit comprises an actively-cooled heat sink affixed to an exterior surface of the vacuum pump stator. 
     
     
         16 . The vacuum pump stator of  claim 15 , wherein the actively-cooled heat sink is operatively connectable, in use, to a liquid cooling circuit. 
     
     
         17 . The vacuum pump stator of  claim 15 , wherein the actively-cooled heat sink is operatively connectable, in use, to a forced air cooling circuit. 
     
     
         18 . A unitary, multi-sage vacuum pump comprising:
 a vacuum pump stator comprising at least two cavities, wherein at least a first cavity of the at least two cavities and a second cavity of the at least two cavities each comprises a respective rotor-receiving portion shaped to receive at least one pair of intermeshing rotors, and wherein an axis of the respective rotor-receiving portion of the first cavity is offset with respect to an axis of the respective rotor-receiving portion of the second cavity.   
     
     
         19 . The unitary, multi-stage vacuum pump of  claim 18 , further comprising at least one head plate sealingly affixable to the vacuum pump stator. 
     
     
         20 . The unitary, multi-stage vacuum pump of  claim 19 , wherein the at least one head plate comprises a channel or recess forming a conduit for the flow of gas from the first cavity to the second cavity. 
     
     
         21 . The unitary, multi-stage vacuum pump of  claim 19 , wherein the at least one head plate comprises apertures for receiving bearings for a rotor shaft of a rotor of the at least one pair of intermeshing rotors. 
     
     
         22 . A vacuum pump stator comprising:
 a longitudinal member arranged to cooperate with end members disposed at opposing ends of the longitudinal member such that at least two pumping volumes are defined by respective portions of the longitudinal member and end members, each pumping volume of the at least two pumping volumes having a longitudinal axis and being arranged to accommodate a pump rotor disposed on a shaft that is disposed parallel to the longitudinal axis, the longitudinal axis of a first pumping volume of the at least two pumping volumes being parallel to and offset from the longitudinal axis of a second pumping volume of the at least two pumping volumes, wherein a portion of the longitudinal member that defines the first pumping volume comprises a main body and a second body attachable to the main body.   
     
     
         23 . The vacuum pump stator of  claim 22 , wherein the second pumping volume is defined only by the respective portion of the main body and respective portions of the end members. 
     
     
         24 . The vacuum pump stator of  claim 22 , wherein the second pumping volume is defined by the respective portion of the main body, a portion of a third body attachable to the main body, and the respective portions of the end members. 
     
     
         25 . The vacuum pump stator of  claim 22 , wherein a first end member of the end members that partially defines the first pumping volume is integrally formed with a second end member of the end members that partially defines the second pumping volume. 
     
     
         26 . The vacuum pump stator of  claim 25 , wherein the first and second end members are formed by a single plate. 
     
     
         27 - 28 . (canceled)