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szielinski
Joined: 13 Jul 2003
Posts: 94
Location: Canberra, Australia
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 Posted: Sun Sep 26, 2004 17:50 Post subject: Can't see the impellor for the vanes... |
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I have looked at cutaway diagrams of centrifugal superchargers and they often seem to have rotating guide vanes in front of the impellor. My understanding is that these vanes direct air in an optimal manner onto the impellor.
Pictures of separate RGV's that I have seen have a spline inside, inferring to me that they are not mounted on a bearing but spin with the impellor shaft.
My question is this - why have two pieces ?
Why not cast an impellor extended at the inlet the same shape as the guide vanes ? |
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kmccutcheon
Joined: 13 Jul 2003
Posts: 298
Location: Huntsville, Alabama USA
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| Posted: Sun Oct 03, 2004 10:32 Post subject: |
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| Quote: | My question is this - why have two pieces ?
Why not cast an impellor extended at the inlet the same shape as the guide vanes ? |
The rotating guide vanes (also called inducer) were made separately to ease the manufacturing process. Supercharger impellers were usually forged in order to endure the stresses of rotating at very high speeds. Parts produced by the forging process required extensive machining to produce their final shape. The complex shape of a one-piece impeller with inducer was beyond the machining technology at the time (we could now produce them with multi-axis computer-controlled machining centers) Hence, the inducer section was fabricated separately from the impeller. Ford had a patent that claimed to produce centrifugally casting impellers using permanent molds that were as strong as forged impellers and very near their final shape. It is possible that this technique could have produced one-piece impellers with inducers. So far as I know, this production method, if used at all, was only used by Ford.
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Kimble D. McCutcheon |
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