Combined suction port of centrifugal fan

Abstract

The combined suction inlet (KUU) of a centrifugal fan according to claim 1, consisting of a welded metal subassembly (ZMP) and a spatially printed plastic piece (2K1), can replace the printed inlet (TUU), for which printing of a metal sheet of thickness (sK) requires expensive tools and a subcontractor, and in addition, a smaller clearance to the rotating wheel cover rim can be achieved than with (TUU). In this case, by introducing a third nozzle of a torus surface (2S) between the other two nozzles [conical (1K1) and torus (LU) from a Venturi tube], a negligible increase in aerodynamic resistance (KUU) is achieved compared to (TUU). The surface (2S) is realized by a new torus ring of radius (rS), which must satisfy two conditions. The first is that (rS) is tangent to the surface (LU) of the nozzle from the Venturi tube, and the second is that it is tangent to the conical surface by the sheet thickness (sK) that is created after the part (1K1) is bent by the rollers.A smaller gap (ZK) than (ZT) with a mouth (TUU) is possible because the metal cover ring of the rotating wheel can scrape a small volume of plastic around a circle of diameter (dFK) without any operational consequences in the event of scraping due to the asymmetry of the gap. According to claim 2, it is possible to maintain the same shape of the flow channel on (KUU) as on (TUU), if (rs) is sufficiently reduced in relation to (rS), with a negligible change in the slope (AS3) in relation to the slope (AS1) of (TUU). It is used in cases where larger dimensional tolerances are required when bending sheet metal with a thickness of (sK) with rollers. The combined suction port (KUU) of a centrifugal fan according to claim 1, consisting of a welded metal subassembly (ZMP) and a spatially printed plastic piece (2K1), can replace the printed port (TUU), for which printing of a metal sheet of thickness (sK) requires expensive tools and a subcontractor, and in addition, a smaller clearance to the rotating wheel cover rim can be achieved than with (TUU).In this case, by introducing a third nozzle of a torus surface (2S) between the other two nozzles [conical (1K1) and torus (LU) from a Venturi tube], a negligible increase in aerodynamic resistance (KUU) is achieved compared to (TUU). The surface (2S) is realised by a new torus ring of radius (rS), which must satisfy two requirements. The first one is that (rS) is tangent to the surface (LU) of the nozzle from the Venturi tube, and the second is that it is tangent to the conical surface by the sheet thickness (sK) that is created after the part (1K1) is bent by the rollers. A smaller gap (ZK) than (ZT) with the mouth (TUU) is possible because the metal cover ring of the rotating wheel in the case of scraping due to the asymmetry of the gap can scrape a small volume of plastic around a circle of diameter (dFK) without any propulsive consequences.According to claim 2, it is possible to maintain the same shape of the flow channel on (KUU) as on (TUU), if (rs) is sufficiently reduced in relation to (rS), with a negligible change in the slope (AS3) in relation to the slope (AS1) from (TUU). It is used in cases where larger dimensional tolerances are required when bending sheet metal with a thickness of (sK) by rollers.