Impeller for a high-speed turbomachine

Claim 2

In an impeller wheel for a high-speed turbomachine having a shaft; and a hub frictionally fastened on said shaft through a tapered fit therebetween; the improvement comprising the combination of: a. said impeller wheel being a centrifugal radially-shaped impeller having a predetermined width; b. said hub being an elongate cylindrical sleeve extending into said impeller wheel in an axial direction; c. said impeller wheel encompassing said shaft and said hub so as to form a narrow radial gap therebetween; and d. said hub at the axial end thereof remote from said impeller wheel including a thin-walled, cylindrical connecting part extending radially outwardly and being welded at its free end to said impeller wheel, said hub being an elongated cylindrical sleeve extending partly into a central bore of said impeller wheel in an axial direction.

Claim 3

An impeller as claimed in claim 1, wherein said cylindrical connecting part is friction-welded to said impeller wheel

Claim 4

An impeller according to claim 1 wherein said impeller comprises a wheel with a substantially thin web in relation to the length of said hub along the axis of said shaft; said wheel carrying blades; said connecting part having a nose-shaped portion spaced from the weld between said wheel and said connecting part for directing through it flow relative to said blades.

Claim 5

An impeller according to claim 1 wherein said connecting part has a nose-shaped portion spaced from the weld between said impeller wheel and said connecting part for directing through it flow relative to said impeller wheel; said connecting part having a ring-shaped projecting portion extending towards the axis of said shaft; and a threaded nut on said shaft and bearing against said ring-shaped portion, said ring-shaped portion being a stop and locating said hub on said shaft in predetermined position.

Claim 6

An impeller according to claim 1 wherein said radial gap comprises a gap portion between said shaft and part of said impeller wheel and a second gap portion connected to said first gap portion and extending between said hub and a further part of said impeller wheel.

Claim 7

An impeller according to claim 1 wherein said impeller comrpises a wheel with a substantially thin web in relation to the length of said hub along the axis of said shaft; said wheel carrying blades, said connecting part having a nose-shaped portion spaced from the weld between said wheel and said connecting part for directing fluid flow relative to said blades; said connecting part having a ring-shaped projecting portion extending toward the axis of the shaft; and a threaded nut on said shaft and bearing against said ring-shaped portion, said ring-shaped portion being a stop and locating said hub on said shaft in predetermined position, said radial gap comprising a first gap portion between said shaft and part of said wheel and a second gap portion connected to said first gap portion and extending between said hub and a further part of said wheel, said gap terminating in a substantially wider internal annular space communicating with said connecting part and said further part of said wheel, said impeller having a central bore of substantially small diameter located radially inwards of the main mass of said impeller for reducing circumferential stresses along said bore arising from centrifugal forces, said narrow radial gap being between said bore and said shaft, said hub being held on said shaft only by friction, said hub having a substantially small mass for inhibiting enlargement of said hub by centrifugal forces and loosening the frictional connection between said hub and said shaft, said hub extending into said central bore of that part of said impeller having relatively low mass.