Rotor for transferring air

Abstract

A multiple-type vacuum pump has a simple construction and superior durability. The multiple-type vacuum pump has the capacity to perform air evacuation at high velocities in the low to high vacuum zone range. The multiple-type vacuum pump includes: a screw type pump air transfer portion arranged at a downstream portion of the outer surface of a rotor and has a plurality of screw threads and screw grooves with a width of 5 mm or more; a turbo-molecular type pump air transfer portion arranged at an upstream portion and has a plurality of vanes and air transfer grooves; vanes having vane widths of 3 mm or less at the upstream edge, and formed so that the downstream edge is continuous with the upstream edge of the screw threads; a downstream edge of the base of the air transfer grooves formed so as to be continuous with the upstream edge of the base of the screw grooves. The turbo-molecular type pump air transfer portion takes the air brought in from the upstream edge at the time of rotation, compresses it and transfers it to the upstream edge of the screw type pump air transfer portion.

What is claimed is:  
     
         1 . A multiple-type vacuum pump, comprising the following constructional requirements (A01) ˜ (A04): 
 (A01) a rotor rotating, within a casing having a cylindrical inner surface, around a rotary shaft disposed in coaxial alignment with said casing, said rotor having an air transfer portion on an outer surface thereof for transferring air in a direction of said rotary shaft at the time of rotation;    (A02) said air transfer portion having a turbo-molecular type pump air transfer portion located at an upstream portion of the air transfer direction, and a screw type pump air transfer portion located at a downstream portion;    (A03) said screw type pump air transfer portion having a plurality of screw threads each having a spiral shape with a width of 5 mm or more and disposed circumferentially at prescribed intervals in said downstream portion of said outer surface of said rotor, and screw grooves formed between each of said screw threads, said screw type pump air transfer portion taking in the air that has streamed into an upstream edge thereof at the time of rotation and transferring it to the downstream side; and    (A04) said turbo-molecular type air transfer portion having a plurality of vanes with a fixed vane angle and formed circumferentially at prescribed intervals in said upstream portion of said outer surface of said rotor, and air transfer grooves formed between each of said vanes, each of said vanes having an upstream edge with a width of 3 mm or less and a downstream edge formed as to be continuous with an upstream edge of said screw threads, a downstream edge of a base of said air transfer grooves formed as to be continuous with an upstream edge of a base of said screw grooves, wherein said turbo-molecular type air transfer portion takes the air that has been brought in from an upstream edge at the time of rotation, compresses it, then transfers it to the upstream edge of said screw type pump air transfer portion.    
     
     
         2 . The multiple-type vacuum pump as recited in    claim 1   , wherein said turbo-molecular type pump air transfer portion comprises the following constructional requirements (A05): 
 (A05) each of said plurality of vanes has a thickness that is identical to a thread width of said screw threads at the downstream edge of said vane and that decreases as said vanes make their way to the upstream edge.    
     
     
         3 . The multiple-type vacuum pump as recited in    claim 1   , wherein said turbo-molecular type pump air transfer portion comprises the following constructional requirements (A06): 
 (A06) each of said plurality of vanes has a reducing thickness portion which is equal to the width of said screw threads at the downstream edge thereof and which narrows as it goes toward the upstream edge thereof, and a uniformed thickness portion on an upstream side of said reducing thickness portion.    
     
     
         4 . The multiple-type vacuum pump as recited in    claim 2    or    3   , wherein said turbo-molecular type pump air transfer portion comprises the following constructional requirements (A07): 
 (A07) each of said plurality of vanes are made up of a plate-shaped member whose thickness is greater at the downstream edge than at the upstream edge.  
 
     
     
         5 . The multiple-type vacuum pump as recited in    claim 2    or    3   , wherein said turbo-molecular type pump air transfer portion comprises the following constructional requirements (A08): 
 (A08) each of said plurality of vanes are made up of a plate-shaped member having a flat plate portion at an upstream portion thereof and a curved plate portion at a downstream portion thereof that is smoothly connected to the upstream edge of said screw type pump air transfer portion.  
 
     
     
         6 . The multiple-type vacuum pump as recited in any one of claims  1  through  5 , wherein said turbo-molecular type pump air transfer portion comprises the following constructional requirements (A09): 
 (A09) the upstream edge portion of each of said plurality of vanes is curved at the downstream side toward the air transfer direction, and the downstream portion thereof is smoothly connected to the upstream edge of said screw type pump air transfer portion.  
 
     
     
         7 . The multiple-type vacuum pump as recited in any one of claims  1  through  6 , wherein said turbo-molecular type pump comprises the following constructional requirements (A10): 
 (A10) said air transfer grooves are formed so as to become deeper as they go toward an upstream edge thereof.  
 
     
     
         8 . The multiple-type vacuum pump as recited in    claim 7   , wherein said turbo-molecular type pump air transfer portion comprises the following constructional requirements (A011): 
 (A011) a base diameter, which is a diameter of a circle including a circumference of a base of said vanes that lie in a cross-sectional plane perpendicular to said rotary shaft, is formed so as to be on a conical plane whose diameter becomes smaller as it goes toward the upstream side.    
     
     
         9 . The multiple-type vacuum pump as recited in any one of claims  1  through  8 , wherein said turbo-molecular type pump air transfer portion comprises the following constructional requirements (A012): 
 (A012) a spacing chord ratio (So/f) of said turbo-molecular type pump air transfer portion satisfies the following formula:  
 1−0.2≦( So/f )≦1+0.2  
 where f represents a length of each of said plurality of vanes from their upstream to downstream edges thereof, and So represents a space between adjacent each vane.  
 
     
     
         10 . The multiple-type vacuum pump as recited in    claim 9   , wherein said spacing chord ratio (So/f) comprises the following constructional requirements (A013): 
 (A013) said spacing chord ratio (So/f) is calculated such that said space between adjacent each vane So is the average value of each of the spaces from the upstream edge to the downstream edge, between adjacent each vane.    
     
     
         11 . The multiple-type vacuum pump as recited in any one of claims  1  through  10 , wherein said air transfer portion comprises the following constructional requirements (A014): 
 (A014) said vane angle θ to a screw tilt angle α1 of the upstream edge of said screw threads satisfy: θ≧α1.  
 
     
     
         12 . The multiple-type vacuum pump as recited in any one of claims  1  through  11 , wherein said air transfer portion comprises the following constructional requirements (A015): 
 (A015) an upstream edge vane angle θ1 of the above-mentioned vanes, the downstream edge vane angle θ2, and the screw tilt angle α1 of said screw threads satisfy: θ1≧θ2=α1.  
 
     
     
         13 . The multiple-type vacuum pump as recited in any one of claims  1  through  12 , wherein said turbo-molecular type pump air transfer portion comprises the following constructional requirements (A016): 
 (A016) a groove width ratio {W 2 /(W 1 +W 2 )} is set at {W 2 /(W 1 +W 2 )}≧9.5, where W 1  is the width of the upstream edge of said vanes, and W 2  is the width of said air transfer grooves.  
 
     
     
         14 . The multiple-type vacuum pump as recited in any one of claims  1  through  13 , wherein said turbo-molecular type pump air transfer portion further comprises the following constructional requirements (A017): 
 (A017) a plurality of additional vanes provided on the upstream portion thereof.  
 
     
     
         15 . The multiple-type vacuum pump as recited in any one of claims  1  through  14 , comprising the following constructional requirements (A018): 
 (A018) a turbo-molecular pump having a plurality of dynamic vanes and a plurality of static vanes, arranged alternately along the direction of air transfer at a further upstream side of the upstream edge of said turbo-molecular type pump air transfer portion, wherein said dynamic vanes are provided around an outer circumference of said rotor, and said static vanes are provided within an inner surface of said casing.  
 
     
     
         16 . The multiple-type vacuum pump as recited in any one of claims  1  through  15 , wherein said air transfer portion comprises the following constructional requirements (A019): 
 (A019) a cubical flow volume (V 1 ) at the upstream edge of said screw type pump air transfer portion, under steady rotational conditions of said rotor, a cubical flow volume (V 2 ) and compression ratio (n) at the upstream edge of said turbo-molecular type pump air transfer portion satisfy: V 1 =V 2 /n.  
 
     
     
         17 . The multiple-type vacuum pump as recited in any one of claims  1  through  16 , wherein said air transfer portion comprises the following constructional requirements (A020): 
 (A021) said screw type pump air transfer portion and said turbo-molecular type pump air transfer portion are formed as one integral structure.  
 
     
     
         18 . The multiple-type vacuum pump as recited in any one of claims  1  through  17 , comprising the following constructional requirements (A021) and (A022): 
 (A021) a flow straightening member having an air flow guide surface formed to be a symmetrical curved plane with respect to an axis which protrudes toward the upstream side from the upstream edge of said turbo-molecular type air transfer portion;  
 (A022) said air flow guide which guides air into a base plane of the upstream edge of said air transfer grooves of said turbo-molecular type pump air transfer portion.  
 
     
     
         19 . The multiple-type vacuum pump as recited in any one of claims  1  through  18 , comprisig the following constructional requirements (A023) and (A024): 
 (A023) an air outlet space which is ring-shaped formed by a larger diameter cylindrical wall and a smaller diameter cylindrical wall, and which takes in the air that has been discharged from said screw type pump air transfer portion; and  
 (A024) an air outlet ( 2   d ;  2   e ) having an air circulation groove ( 2   d   1 ;  2   e   1 ) which is formed as rings by a larger diameter cylindrical wall and a smaller diameter cylindrical wall each connected to each of said larger diameter cylindrical wall and said smaller diameter cylindrical wall of said air outlet space, respectively, and which discharges air while circulating it, and a tangential air outlet ( 2   d   2 ;  2   e   2 ) extending toward the tangents of said larger diameter cylindrical wall and is connected to a downstream edge of said air circulation groove.  
 
     
     
         20 . The multiple-type vacuum pump as recited in    claim 19   , wherein said air circulation groove comprises the following constructional requirements (A025): 
 (A025) a spiral-formed base, and performs air exhaust along the spiral base.