Rotary compressor

Abstract

The present invention concerns a rotary compressor for compressing a gaseous medium, comprising an impeller ( 2 ), a drive unit ( 3 ) and a magnetic coupling ( 4 ) comprising a rotating inner rotor ( 41 ), a rotating outer rotor ( 42 ) and a can ( 43 ), wherein the inner rotor ( 41 ) is connected to the impeller ( 2 ), wherein the impeller ( 2 ) comprises a continuous solid portion ( 25 ), wherein a first row ( 21 ) and a second row ( 22 ) of blades ( 23 ) are provided at the outer circumference of the solid portion ( 25 ) of the impeller, the first and second row of blades being separated by a circumferential middle wall ( 20 ), and wherein the blades ( 23 ) of the first row ( 21 ) are offset in circumferential direction relative to the blades ( 23 ) of the second row ( 22 ).

1 . Rotary compressor for compressing a gaseous medium, comprising:
 an impeller;   a drive unit; and   a magnetic coupling having a rotating inner rotor, a rotating outer rotor and a can;   wherein the inner rotor is connected to the impeller;   wherein the impeller includes a continuous solid portion;   wherein a first row and a second row of blades are provided at the outer circumference of the solid portion of the impeller, the first and second row of blades being separated by a circumferential middle wall; and   wherein the blades of the first row are offset in circumferential direction relative to the blades of the second row.   
     
     
         2 . Rotary compressor further comprising a housing having an inlet, an outlet and a flow path, wherein the flow path connects the inlet with the outlet and is provided in an arc shape of at least 300°, preferably 315°, of the outer circumference of the impeller. 
     
     
         3 . Rotary compressor according to  claim 2 , wherein the flow path and/or the inlet and/or the outlet comprise a surface having a plurality of dimples. 
     
     
         4 . Rotary compressor according to  claim 2 , wherein the flow path has a surface coating, preferably a PTFE-coating. 
     
     
         5 . Rotary compressor according to  claim 2 , wherein a connecting portion between the inlet and/or outlet with the flow path is edge-free. 
     
     
         6 . Rotary compressor according to  claim 1 , wherein the number of blades of the first row and the second row is identical. 
     
     
         7 . Rotary compressor according to  claim 1 , wherein the first row and the second row of blades are offset in circumferential direction by half of a length of one spacing provided between two neighboring blades, and preferably offset by an arc length of 4°. 
     
     
         8 . Rotary compressor according to  claim 1 , wherein the blades are straight radial blades being tapered in radial outer direction. 
     
     
         9 . Rotary compressor according to  claim 1 , wherein the can includes an inner barrier and an outer barrier, wherein an electrostatic insulation layer is arranged between the inner and outer barrier. 
     
     
         10 . Rotary compressor comprising an impeller shaft supported by a first bearing and a second bearing, wherein the first bearing is a double bearing. 
     
     
         11 . Rotary compressor according to  claim 7 , wherein a distance between neighboring blades in a circumferential direction has an arc length of 10° or less. 
     
     
         12 . Rotary compressor according to  claim 1 , wherein a thickness of the middle wall of the impeller is the same as a thickness of the blades at an outermost portion of the blades. 
     
     
         13 . Gas lubricated mechanical seal arrangement comprising:
 a rotating ring;   a stationary ring; and   a gas supply unit including a main compressor and an auxiliary compressor;   wherein the auxiliary compressor is a rotary compressor according to  claim 1 .