Vacuum pump

Abstract

Each of the stationary blade portions is formed by two or more divided stationary blade portions, and has abutting ends in both circumferential ends, the stationary blade portion is formed by abutting the abutting ends of the divided stationary blade portions with each other. Each of the divided stationary blade portions has an outer circumferential rim nipped by the spacers, an inner circumferential rim positioned in a front end on the inner circumferential side of the stationary blade portion, and a plurality of stator blades formed between the outer circumferential rim and the inner circumferential rim. In abutting ends of the outer circumferential rims where the plurality of divided stationary blade portions is abutted with each other, at least one of the outer circumferential rims has a cutout forming a gap together with the other facing outer circumferential rim.

What is claimed is: 
     
         1 . A vacuum pump having an exhaust function portion in which stationary blade portions nipped by spacers are respectively arranged between rotating blade portions arranged in multiple stages, wherein
 each of the stationary blade portions is formed by two or more divided stationary blade portions,   each of the divided stationary blade portions has abutting ends in both circumferential ends, the stationary blade portion is formed by abutting the abutting ends of the divided stationary blade portions with each other,   each of the divided stationary blade portions has an outer circumferential rim nipped by the spacers, an inner circumferential rim positioned in a front end on the inner circumferential side of the stationary blade portion, and a plurality of stator blades formed between the outer circumferential rim and the inner circumferential rim, and   in abutting ends of the outer circumferential rims where the plurality of divided stationary blade portions is abutted with each other, at least one of the outer circumferential rims has a cutout forming a gap together with the other facing outer circumferential rim.   
     
     
         2 . The vacuum pump according to  claim 1 , wherein
 each of the divided stationary blade portions is manufactured from a flat plate into the same shape,   an abutting end surface of the inner circumferential rim and an abutting end surface of the outer circumferential rim are formed as a first abutting surface in the one abutting end of the divided stationary blade portion, an end surface of the inner circumferential rim, an end surface of the outer circumferential rim, and an end surface of an edge member forming an opening portion are formed as a second abutting surface in the other abutting end, and   the first abutting surface and the second abutting surface are abutted with each other so as to form the stationary blade portion.   
     
     
         3 . The vacuum pump according to  claim 1 , wherein
 the cutout is provided in the outer circumferential rim as a rectangular shape with a predetermined width in the circumferential direction and a predetermined length in a radial direction.   
     
     
         4 . The vacuum pump according to  claim 1 , wherein
 a bending portion bent from the inner circumferential rim is provided in at least one of end surfaces of the inner circumferential rims where the plurality of divided stationary blade portions is abutted with each other.   
     
     
         5 . The vacuum pump according to  claim 1 , wherein
 the gap is determined based on maximum tolerance α of circumferential length between both the abutting ends, and/or maximum tolerance β between an outer circumferential surface of the stationary blade portion assembled from the divided stationary blade portions and an inner circumferential surface of the spacer.