Vacuum pump, stator blade, and spacer

Abstract

In a vacuum pump in which the rotor blade in one stage has an outer diameter that is smaller at an outlet port side, or the rotor blade in one stage has an inner diameter that is larger at an outlet port side, at least one of an outer circumference portion or an inner circumference portion of the stator blade that is located immediately above the rotor blade having a smaller outer diameter or immediately above the rotor blade having a larger inner diameter has a tapered surface sloping down to an outlet port side. By providing the tapered surface, entering molecules are reflected at a right angle, sent toward an inner circumference side, and hit by the rotor blade in the upper stage. The molecules are thus sent to a next exhaustion stage.

What is claimed is: 
     
         1 . A vacuum pump comprising:
 a casing that has an inlet port and an outlet port;   a rotating shaft that is rotationally supported inside the casing;   rotor blades in multiple stages that are fixed to the rotating shaft and rotatable together with the rotating shaft; and   stator blades in multiple stages that are fixed to the casing and located between the rotor blades,   the rotor blade in at least one stage of the rotor blades in multiple stages being configured to have an outer diameter that is smaller at an outlet port side than at an inlet port side, or the rotor blade in at least one stage of the rotor blades in multiple stages being configured to have an inner diameter that is larger at the outlet port side than at the inlet port side, wherein 
 an outer circumference portion or an inner circumference portion of the stator blade that is located immediately above the rotor blade having a smaller outer diameter or immediately above the rotor blade having a larger inner diameter has a tapered surface sloping down to the outlet port side. 
   
     
     
         2 . The vacuum pump according to  claim 1 , wherein,
 the stator blade includes a plurality of radially arranged blades and an inner rim or an outer rim that holds the plurality of blades, and   an outer circumference surface of the inner rim or an inner circumference surface of the outer rim has a tapered surface sloping down to the outlet port side.   
     
     
         3 . The vacuum pump according to  claim 1 , wherein 
 the stator blade includes a plurality of radially arranged blades and a spacer portion that holds the plurality of blades and enables positioning of the stator blade in a height direction, and   an inner circumference surface of the spacer portion has a tapered surface sloping down to the outlet port side.   
     
     
         4 . The vacuum pump according to  claim 2 , wherein the stator blade is undercut to surfaces of the plurality of blades facing the outlet port side. 
     
     
         5 . The vacuum pump according to  claim 2 , wherein the stator blade has a vertical surface or a tapered surface on a rear side of the plurality of blades. 
     
     
         6 . The vacuum pump according to  claim 1 , wherein
 a protrusion is provided that extends within a range of the stator blade in a height direction from a spacer portion that holds a casing side of the stator blade and enables positioning of the stator blade in the height direction, and   at least a part of an inner circumference surface of the spacer portion and the protrusion has a tapered surface sloping down to the outlet port side.   
     
     
         7 . A stator blade for a vacuum pump including a casing having an inlet port and an outlet port, the stator blade comprising:
 a plurality of blades arranged radially; and   an inner rim or an outer rim holding the plurality of blades, wherein 
 an outer circumference surface of the inner rim or an inner circumference surface of the outer rim has a tapered surface sloping down toward an outlet port side. 
   
     
     
         8 . A spacer for a vacuum pump including a casing having an inlet port and an outlet port, the spacer including:
 a spacer portion that is configured to, when a stator blade having a plurality of radially arranged blades is placed, hold a casing side of the stator blade and enable positioning of the stator blade in a height direction; and   a protrusion that extends from the spacer portion within a range of the stator blade in the height direction, wherein 
 at least a part of an inner circumference surface of the spacer portion and the protrusion has a tapered surface sloping down to the outlet port side. 
   
     
     
         9 . The vacuum pump according to  claim 3 , wherein the stator blade is undercut to surfaces of the plurality of blades facing the outlet port side. 
     
     
         10 . The vacuum pump according to  claim 3 , wherein the stator blade has a vertical surface or a tapered surface on a rear side of the plurality of blades.