US3426965A - Centrifugal fan having removable blade section - Google Patents

Description

Feb. mwsg a. J. KULLING 3,426,%5 CENTRIFUGAL FAN HAVING REMOVABLE BLADE SECTION Filed Jan. 10, 1967 Sheet of J;

INVENTOR.

15445041, Serra-j, 5472"55051, 6924 Jinn/May;

Feb. 11, 1969 G. J. KULLING 3,426,965

CENTRIFUGAL FAN HAVING REMOVABLE BLADE SECTION Filed Jan. 10, 1967 INVENTOR.

Feb. 11, 1969 G. J. KULLING 3,425,965

CENTRIFUGAL FAN HAVING REMOVABLE BLADE SECTION Filed Jan. 10, 1967 Sheet 3 of 5 o //Z o o O o O a I o E o 2 INVENTOR.

gee/I10 Lil 044 10 United States Patent 3,426,965 CENTRIFUGAL FAN HAVING REMOVABLE BLADE SECTION Gerald J. Kulling, Detroit, Mich, assignor to American Standard Inc., a corporation of Delaware Filed Jan. 10, 1967, Ser. No. 608,388 US. Cl. 230--134 Int. Cl. F0411 29/30, 17/16 4 Claims ABSTRACT OF THE DISCLOSURE In the construction of large industrial fans, it is customary to provide a fan wheel within a housing with means for rotating the fan wheel within the housing to direct a gas, such as air, from an inlet opening to an outlet opening. The fan wheel generally includes a pair of spaced rims with a plurality of radially spaced blade assemblies which have a fluid engaging surface for directing the air from the inlet of the housing to the outlet thereof.

In the past it has been customary to form the blade assemblies of a unitary structure which is rigidly secured to the spaced rims. After a particular length of service time, when the gas contains abrasive particles, the air contacting surfaces of the blade assemblies become worn which requires replacement of the entire fan wheel assembly.

The primary object of the present invention is to provide an improved fan wheel having greater service life.

Another object of the invention is to provide an improved fan blade assembly having a fluid contacting surface which permits the portion of the blade surface being subjected to the most abrasive wear to be replaced after deterioration in service.

A further object is to provide an improved fan Wheel blade having a sectionalized fluid engaging surface wherein at least one of the sections may be replaced after deterioration in service.

Other objects of this invention will appear in the following description and appended claims, reference being had to the accompanying drawings forming a part of this specification wherein like reference characters designate corresponding parts in the several views.

In the drawings:

FIGURE 1 is a perspective view of a centrifugal fan incorporating the invention;

FIGURE 2 is a vertical sectional view of a fan wheel assembly including the present invention;

FIGURE 3 is a side elevation of the fan wheel assembly shown in FIGURE 2, with parts thereof broken away for clarity;

FIGURE 4 is an exploded perspective view of the fan blade asembly of the present invention;

FIGURE 5 is an enlarged sectional view taken along lines 5--5 of FIGURE 2;

FIGURE 6 is a view similar to FIGURE 5;

FIGURE 7 is an exploded perspective view of a modified form of fan blade assembly of the present invention; and

FIGURE 8 is a sectional assembled view of the blade assembly embodiment shown in FIGURE 7.

Before explaining the present invention in detail, it is to be understood that the invention is not limited in its application to the details of the contruction and arrangement of parts illustrated in the accompanying drawings, since the invention is capable of other embodiments and of being practiced or carried out in various ways. Also, it is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation.

Generally speaking, the fan wheel blade assembly of the present invention includes a frame having a leading edge, a trailing edge and a fluid or air directing surface intermediate the edges with a section having an uninterrupted surface, forming a part of the air directing surface, which is removably secured in an opening in the frame intermediate the leading and trailing edges.

With particular reference to FIGURE 1 of the drawings, there is shown a centrifugal fan .10 comprising a fan housing 12 made up of a spiral shaped scroll and side sheets, which includes a pair of inlet openings 14 and an outlet opening 16. The fan housing is suitably supported on a floor structure through legs 18 fixedly secured thereto.

A fan wheel assembly 20 (FIG. 2) is received in the housing '12 and includes a shaft 22 which is rotated by suitable drive means, such as an electric motor 24, said motor being operatively interconnected to the shaft 22 and supported adjacent the fan housing on an integral base 26. The shaft 22 is rotatably journaled in suitable bearings 15 (only one being shown) so as to rotate at the origin of the spiral forming the scroll portion of the fan housing.

The fan wheel assembly includes a hub 30 fixedly secured to the shaft 22 by a key 32 and set screws 33 to rotate with the shaft. The hub 30 has an outwardly directed radial center plate 34 removably secured to a flange portion 36 of the hub by suitable bolts or rivets 38.

The fan wheel further includes a pair of spaced rims 40 disposed on opposite sides of the center plate 34* and attached to a plurality of fan wheel blade assemblies 42 intermediate the center piece plate 34 and the respective rims 40.

Each fan wheel blade assembly 42 is identical in construction except opposite hand when disposed on opposite sides of center plate 34 and is shown in the exploded view of FIGURE 4. The blade assembly includes a frame 50 having a leading edge or accurately curved nose piece 52 and a trailing edge or tail piece 54 with a pair of opposed surfaces 56 and 58 formed intermediate the leading and trailing edges. The surface 56 forms the air directing surface of the fan wheel assembly and, therefore, must be free of any surface irregularities which can be acted upon by the flow of air across the surface which can initiate wear on the blade surface and interfere with the flow pattern in a manner detrimental to the aerodynamic performance of the wheel.

According to the invention, the gas engaging surface 56 includes a removable section in the area which is thought to be subjected to the most wear due to the surface configuration of the contacting engaging surface. For this purpose, the frame 50 is provided when a generally rectangular or trapezoidal opening 60 intermediate the leading and trailing edges 52 and 54. This opening is located in a position Where the gas engaging surface is thought to be subjected to the most abrasive action of the contacting air.

The opening 60 is enclosed by a removable section 62 which comprises a plate 64 having an uninterrupted surface thereon which forms a part of the fluid contacting surface 56. The plate is provided with peripheral securing members 66, 67, 82 and 83 which are fixedly secured to the outer edges of the plate 64 by suitable means, such as welding. The peripheral member 66 is fitted to a mounting block 68 which forms a ledge 70 that is adapted to engage an inwardly directed flange 72 disposed along the edge of two sides of the opening 60.

The section 62 is further provided with a plurality of vertically extending rigidifying members 74 fixedly secured to the inner surface of the plate 64 and to the side members 66 and 67. A second or cover plate 76 is adapted to be removably secured to the rigidifying members 74 and peripheral members 66, 67, 82 and 83 in a manner to be described later.

In assembling the blade assembly of the invention, the removable section 62 is aligned with the opening 60 and is moved into the position shown in FIGURE with the cover plate 76 being removed. The section 62 is slid in until the ledge 70 is in contacting engagement with the flange 72 of the opening 60. Thereafter, the entire section 62 is rigidly secured within the opening 60 through securing means 80 extending through openings 81 in the peripheral members 66, 67, 82 and 83, and threadedly received in openings 84 in the frame 50. After the entire peripheral member has been secured to the inner surface forming the opening in the frame 50, the removable cover 76 is secured to the inner or exposed surface of the peripheral member by screws 86 extending through tapered openings 88 in the plate 76 and threadedly received in the peripheral members 66, 67, 82 and 83, as well as the rigidifying members or bars 74.

As can readily be appreciated with reference to FIG- URE 5, the blade assembly provides a removable section which may be replaced upon deterioration in service. Yet the entire surface 56 is substantially continuous without any protrusions, such as rivets or screws, extending beyond the surface of the removable section.

In the modified form of invention shown in FIGURES 7 and 8, the frame 98 is substantially identical in construction to that of the preferred embodiment of the invention. However, in the modified form of the invention, the frame 98 is provided with a pair of recesses 100 and 102 in the opposed surfaces of the frame which form a part of the opening 104 and are disposed outwardly around the peripheral edge of the opening. A plate 106 is of such a size to be received in the recess 100 formed on one surface of the frame 98 and, as in the preferred embodiment of the invention, one surface of the plate 106 is continuous and uninterrupted. The opposite surface of the plate 106 is provided with a peripheral member or bar 108 which is spaced inwardly from the outer edge of the plate and is adapted to engage the peripheral edge of the opening 104 in the frame 98.

A plurality of rigidifying members 110 are disposed against the surface of the plate 106 intermediate the peripheral member or bar 108. The cover plate 112 is likewise provided with rigidifying members 114 which are in alignment with the rigidifying members 110 carried by the plate 106.

In assembling the modified form of blade assembly, the removable section comprising the plate 106, peripheral member 108 and rigidifying members 110 is disposed in the opening 104 with the portion of the plate 106, which extends beyond outer surface of the peripheral member, being received in the recess 100 of the frame 98. The movable section is fixedly secured in the opening 104 by screws 114 extending through openings 116 in the peripheral member 108 and received in threaded openings 118 in the frame 98.

The cover plate 112 is thereafter moved into engagement with the opposite side of the frame 98 and has its edges received in the recess 102. The plate 106 and cover plate 112 are then removably secured to each other by screws 120 extending through counterbored openings 122 in the rigidifying members of 114 on plate 112 and threadedly received in openings 124 in the rigidifying members 110 of plate 106. The plate 112 is further secured to the frame through screws 126 received in tapered openings in the plate and threaded into openings in the frame 98.

The modified form of the invention has the same advantages as the preferred embodiment in that a substantially continuous uninterrupted removable surface forms a part of the fluid contacting surface of the blade assembly.

While two preferred embodiments of the invention have been shown and described, it will be understood that various changes and modifications may be made without departing from the spirit of the invention, and the invention is to be limited only by the following claims.

I claim:

1. A fan wheel blade assembly comprising a frame having a first leading edge, a trailing edge and a first fluid directing surface intermediate said edges having an opening therein, a first plate having an uninterrupted surface the size of said opening, means for removing said first plate in said opening so that said uninterrupted surface forms a part of said first fluid directing surface, a second fluid directing surface on said frame intermediate said edges with said opening extending through said frame and said second fluid directing surface, and a second plate, rigidifying means fixed to at least one of said plates, and securing means for removably securing said second plate in said opening to form a part of said second fluid directing surface.

2. A centrifugal fan wheel comprising a back wall and a rim spaced axially therefrom to define an inlet opening for gas flowing toward said wall; a plurality of air foil blades extending between the back wall and rim; each blade having inner and outer edges connected by a high pressure leading face and a low pressure trailing face; each blade comprising a frame permanently secured between the backwall and rim; each frame comprising an inner nose piece defining the aforementioned inner edge, an outer tail piece defining the aforementioned outer edge and parts of the aforementioned leading and trailing faces, and two side members interconnecting the nose piece and tail piece; said side members being permanently affixed to the back wall and rim to secure the frame in the wheel; each blade further comprising a removable assembly consisting of a first removable blade section spanning the space between the nose piece and tail piece to form a trailing face for the blade, and a second removable blade section spanning the space between the nose piece and tail piece to form a leading face for the blade; first means securing the two removable blade sections to one another; and second means securingone of the removable sections to the frame; said frame having ledge-forming surfaces which engage the removable assembly to resist displacement of the assembly out of the wheel under the effect of centrifugal force.

3. A fan wheel blade assembly comprising a frame having a leading edge section, a trailing edge section, and a pair of side frame sections connecting said leading and trailing edge sections to each other in opposed spaced relationship to define a central opening in said frame, an integral flange on said frame extending around the periphery of said opening and having an outer surface continuous with the adjacent surfaces of said edge and side frame sections and defining therewith a portion of one of the fluid engaging surfaces of said fan blade, said flange having an opposed inner surface defining an inwardly facing shoulder extending around the periphery of said opening, a plate assembly including a plate adapted to fit within said opening and having an outer surface adapted to define the remaining portion of said one fluid engaging surface of said fan, a securing member fixed to the inner surface of said plate and extending around the entire periphery thereof, said securing member projecting beyond the edges of said plate to underlie and engage said shoulder when said plate is disposed within said opening, and means for detachably securing said securing member to said frame.

4. The invention defined in claim 3 further comprising a plurality of rigidifying members secured to the inner surface of said plate and extending laterally thereacross between opposed points on the inner periphery of said securing member, and a cover plate removably secured to said securing member and to said rigidifying members to fit Within said opening and define the major portion of a second fluid engaging surface of said blade.

References Cited UNITED STATES PATENTS 1,071,660 8/1913 Banner 230-13445 1,600,690 9/1926 Meyer 230-13445 1,635,840 7/1927 Haw 170-159 4/1934 Dowson 103-115 12/1934 Rijswijk 230-13445 12/1934 Whiton 230-13448 7/1935 Baumann 170-159 12/1940 Hart et al 170-159 6/1963 Ramme 170-159 FOREIGN PATENTS 2/1957 France.

US. Cl. X.R.

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