Diffusor

Abstract

The guide device for the diffusor at the compressor impeller outlet of a radial compressor has guide blades with stepped inlet edges. The step is implemented by setting back the hub-side inlet edge. This meridional stepping divides the guide blades into two component blades, of which the first component blade is made longer than the second component blade. The set-back of the inlet edge of the hub-side component blade and the associated superposition of the noise fields which are produced on the front and rear inlet edge of the diffusor leads to improvement of the acoustic properties of the compressor.

1 . Guide device for a diffusor on a compressor impeller outlet of a radial compressor, comprising:
 a plurality of guide blades, the guide blades being located between an inlet-side housing part and a hub-side housing part,   each guide blade being divided into,
 a first, inlet-side component blade; and 
 at least one second, hub-side component blade, wherein a blade profile length of the first component blade being larger than a blade profile length of the second component blade, the first component blade having a height from 30 to 70 percent of a sum of heights of all component blades along a blade inlet edge, and 
   a distance from a blade inlet edge of the first component blade to an outside radius of outflow edges of moving blades is 50 to 85 percent of a distance from an inlet edge of the second component blades to the outside radius of the outflow edges of the moving blades, so that in operation of the guide device in a radial compressor, a first part of an outflow of the compressor impeller can be routed over the first component blade and a second part of the outflow which flows with a stronger radial component is routed over the second component blade which has a set back blade inlet edge relative to the blade inlet of the first component blade.   
     
     
         2 . Guide device as claimed in  claim 1 , wherein the first component blade on the blade inlet edge has an inside diameter which is 110 to 125 percent of an outer diameter of a compressor impeller radius. 
     
     
         3 . Guide device as claimed in  claim 1 , wherein between the first component blade and the second component blade there is at least one third component blade, the third component blade extending over a length which is between the blade profile length of the first component blade and the blade profile length of the second component blade. 
     
     
         4 . Guide device for the diffusor of a radial compressor as claimed in  claim 1 , wherein outflow edges of the component blades jointly form a continuous outflow edge of the guide blades. 
     
     
         5 . Guide device for the diffusor of a radial compressor as claimed in  claim 1 , wherein a blade profile of the second component blade lies completely within a blade profile of the first component blade. 
     
     
         6 . Guide device for the diffusor of a radial compressor as claimed in  claim 1 , wherein a blade profile of one second component blade corresponds to a blade profile of one first component blade scaled with a reduction factor. 
     
     
         7 . An exhaust gas turbocharger, comprising:
 a guide device for a diffusor on a compressor impeller outlet of a radial compressor, including:   a plurality of guide blades, the guide blades being located between an inlet-side housing part and a hub-side housing part,   each guide blade being divided into,
 a first, inlet-side component blade; and 
 at least one second, hub-side component blade, wherein a blade profile length of the first component blade being larger than a blade profile length of the second component blade, the first component blade having a height from 30 to 70 percent of a sum of heights of all component blades along a blade inlet edge, and 
   a distance from a blade inlet edge of the first component blade to an outside radius of outflow edges of moving blades is 50 to 85 percent of a distance from an inlet edge of the second component blades to the outside radius of the outflow edges of the moving blades, so that in operation of the guide device in a radial compressor, a first part of an outflow of the compressor impeller can be routed over the first component blade and a second part of the outflow which flows with a stronger radial component is routed over the second component blade which has a set back blade inlet edge relative to the blade inlet of the first component blade.   
     
     
         8 . Guide device for the diffusor of a radial compressor as claimed in  claim 3 , wherein outflow edges of the component blades jointly form a continuous outflow edge of the guide blades. 
     
     
         9 . Guide device for the diffusor of a radial compressor as claimed in  claim 3 , wherein a blade profile of the second component blade lies completely within a blade profile of the first component blade. 
     
     
         10 . Guide device for the diffusor of a radial compressor as claimed in  claim 3 , wherein a blade profile of one second component blade corresponds to a blade profile of one first component blade scaled with a reduction factor. 
     
     
         11 . The exhaust gas turbocharger, as claimed in  claim 7 , wherein a blade profile of one second component blade corresponds to a blade profile of one first component blade scaled with a reduction factor.