Insulated hub arrangement for high temperature centrifugal fan

Claim 2

In a centrifugal fan of the type having a thermally insulated hub, an improved heat shielding and insulating arrangement for that type of hub which is a one-piece member having an axially extending root portion which is heat shrunk on onto a rotary shaft and turns up at its inner end and terminates in a radially extending flange lying in a plane normal to the axis of the shaft, and which has the radially inner portion of a wheel plate secured by fasteners to the flange, comprising: a collar encircling and secured to said shaft at the outer end of said root portion; a heat shield including a circumferential portion having a shape generally following the contour of said root portion in sufficiently spaced apart relation with the outer surface of said root portion to form an annular space therebetween to accommodate a depth of thermal insulation determined in accordance with the temperature variation design conditions for the fan, said circumferential portion comprising at least a pair of circumferentially extending segments, each of which includes means along its opposite axially extending edges for fastening to the adjacent segment; thermal insulation in said annular space; means fastening said circumferential segments to said root portion; an end disc for said shield having a central opening to accommodate said shaft in relatively close fitting relation to substantially minimize leakage of hot gases handled by said fan into the space in said cover adjacent said collar; means securing said end disc in fixed relation to said collar and said circumferential portion; and said circumferential portion being unattached to said wheel plate so that movement of said plate in accordance with temperature changes thereof is not directly translated to said circumferential portion.

Claim 3

An arrangement according to claim 1 wherein: said circumferential portion comprises one pair of said segments, each extending through about 180° C., and each segment includes outwardly directed flange means at the axially extending edges for accommodating fastening.

Claim 4

An arrangement according to claim 1 wherein: said collar projects radially outwardly beyond the radially outer surface of the end portion of said hub root portion to a degree corresponding to the depth of insulation desired at said outer end portion.

Claim 5

An arrangement according to claim 1 wherein: said fan includes a pair of hubs of generally mirror image form and relation on said shaft; said wheel plate is sandwiched between said flanges; and a heat shielding and insulating arrangement is provided for each hub.

Claim 6

In a centrifugal fan of the type having a thermally insulated hub, an improved heat shielding and insulating arrangement for that type of hub which is a one-piece member having an axially extending root portion which is heat shrunk onto a rotary shaft and turns up at its inner end and terminates in a radially extending flange lying in a plane normal to the axis of the shaft, and which has the radially inner portion of a wheel plate secured by fasteners to the flange, comprising: a collar encircling and secured to said shaft at the outer end of said root portion; thermal insulation encompassing the root portion of said hub; a cover of generally elongated, can-shaped form around said insulation and at the outer side of said collar, and comprising a circumferential portion and an outer end portion; said circumferential portion comprising at least a pair of circumferentially extending segments, each of which includes means along its opposite axially extending edges for fastening to an edge of an adjacent segment; said collar having a larger circumference than said root portion at said outer end so that with the outer end margin of said circumferential portion seating on the circumference of said collar an annular space is defined between the root exterior and said circumferential portion to accommodate said thermal insulation therein; means fastening said circumferential portion to said root portion; said outer end portion of said cover having a central opening to accommodate said shaft in relatively closely fitting relation to substantially minimize leakage of hot gas handled by said fan into the space in said cover adjacent said collar; means securing said outer end portion of said cover in place; and said cover being unsecured to said wheel plate and terminating at its inner open end generally at said turned-up portion of said hub.

Claim 7

In a centrifugal fan of the type having a thermally insulated hub, an improved heat shielding and insulating arrangement for that type of hub which is a one-piece member having an axially extending root portion which is heat shrunk onto a rotary shaft and turns up at its inner end and terminates in a radially extending flange lying in a plane normal to the axis of the shaft, and which has the radially inner portion of a wheel plate secured by fasteners to the flange, comprising: a collar encircling and secured to said shaft at the outer end of said root portion; thermal insulation encompassing the root portion of said hub; a cover of generally elongated, can-shaped form around said insulation and at the outer side of said collar, and comprising a circumferential portion and an outer end portion; said circumferential portion comprising at least a pair of circumferentially extending segments, each of which includes means along its opposite axially extending edges for fastening to an edge of an adjacent segment; said collar having a larger circumference than said root portion at said outer end so that with the outer end margin of said circumferential portion seating on the circumference of said collar an annular space is defined between the root exterior and said circumferential portion to accommodate said thermal insulation therein; means fastening said circumferential portion to said root portion; said outer end portion of said cover having a central opening to accommodate said shaft in relatively closely fitting relation to substantially minimize leakage of hot gas handled by said fan into the space in said cover adjacent said collar; means securing said outer end portion of said cover in place; and said cover being unsecured to said wheel plate and terminating at its inner open end generally at said turned-up portion of said hub.