Dry vacuum pump

Abstract

A dry vacuum pump includes an elastic outer seal and at least one elastic inner seal respectively including a first and a second end annular parts parallel to one another and inserted between a respective end piece and the half-shells, and two side rails connecting the end annular parts and which are at right angles thereto, the side rails being inserted between the half-shells, the at least one inner seal being arranged inside the outer seal so that the at least one inner seal and the outer seal form at least two successive sealing barriers for the gases.

1 . A dry vacuum pump comprising:
 a stator comprising at least one first and one second complementary half-shells and one first end piece and one second end piece, the half-shells and the end pieces being joined together by axial assembly to form at least one pumping chamber of a pumping stage,   two rotor shafts configured to turn synchronously in reverse directions in the at least one pumping stage,   an elastic outer seal and at least one elastic inner seal respectively comprising:   one first and one second end annular parts parallel to one another and inserted between a respective end piece and the half-shells, and   two side rails connecting the end annular parts and which are at right angles thereto, the side rails being inserted between the half-shells, the at least one inner seal being arranged inside the outer seal so that the at least one inner seal and the outer seal form at least two successive sealing barriers for the gases,   wherein the at least one inner seal is formed from a material that is more resistant to corrosion, to abrasion and/or to high temperatures than the material of the outer seal.   
     
     
         2 . The vacuum pump according to  claim 1 , wherein the outer seal is in one piece. 
     
     
         3 . The vacuum pump according to  claim 1 , wherein the at least one inner seal is in one piece. 
     
     
         4 . (canceled) 
     
     
         5 . The vacuum pump according to  claim 1 , wherein the outer seal is made of a fluorinated elastomer material and the at least one inner seal is made of a perfluoroelastomer material. 
     
     
         6 . The vacuum pump according to  claim 1 , wherein the half-shells and the end pieces are joined to one another by axial assembly of a first and second axial nose and a first and second axial void that are complementary, one being borne by the half-shells, the others by the end pieces, the first and second end annular parts being inserted between a respective complementary axial nose and axial void. 
     
     
         7 . The vacuum pump according to  claim 6 , wherein:
 a first and at least one second peripheral annular grooves are formed in at least one axial nose and/or in at least axial void to receive the first and second end annular parts of the outer seal and of the at least one inner seal,   at least two longitudinal grooves are formed in one and/or the other of the half-shells in a joining surface on either side of the pumping chambers, to receive the side rails of the outer seal and of the inner seal.   
     
     
         8 . The vacuum pump according to  claim 1 , wherein at least one injection duct is formed in a half-shell of the stator and emerges through at least one injection orifice in an interstitial space situated between the at least one inner seal and the outer seal, the vacuum pump comprising a gas feed device configured to inject a neutral gas into the injection duct. 
     
     
         9 . The vacuum pump according to  claim 8 , wherein the injection duct emerges in the zone of the interstitial space situated in a joining surface of the half-shells, between two side rails. 
     
     
         10 . The vacuum pump according to  claim 8 , wherein the gas feed device is configured to heat the neutral gas. 
     
     
         11 . The vacuum pump according to  claim 8 , wherein the gas feed device is configured to inject the neutral gas with overpressure. 
     
     
         12 . The vacuum pump according to  claim 1 , wherein at least one suction duct is formed in a half-shell of the stator and emerges in an interstitial space situated between the at least one inner seal and the outer seal, through at least one suction orifice, the suction duct connecting the interstitial space with a pumping chamber or an interstage channel of the vacuum pump. 
     
     
         13 . The vacuum pump according to  claim 12 , wherein the suction duct emerges in the zone of the interstitial space situated in a joining surface of the half-shells, between two side rails. 
     
     
         14 . The vacuum pump according to  claim 1 , further comprising a pressure sensor configured to measure the pressure in an interstitial space situated between the at least one inner seal and the outer seal. 
     
     
         15 . The vacuum pump according to  claim 1 , further comprising a gas sensor configured to determine the presence of at least one corrosive gaseous species in an interstitial space situated between the at least one inner seal and the outer seal. 
     
     
         16 . The vacuum pump according to  claim 1 , wherein the half-shells of the stator form at least two pumping stages mounted in series between a suction and a discharge of the vacuum pump. 
     
     
         17 . The vacuum pump according to  claim 1 , wherein the stator comprises at least two pairs of complementary half-shells, the elastic outer and inner seals respectively comprising at least one interposed annular part inserted between two pairs of half-shells. 
     
     
         18 . The vacuum pump according to  claim 1 , wherein the stator further comprises at least one one-piece pumping stage mounted in series of the at least one pumping stage formed in the at least first and second half-shells.