US 3692428 A
A centrifugal blower has a frusto-conical end wall with a central hub and a plurality of elongated blades disposed parallel with the hub axis and carried around the outer periphery of the end wall. A continuous ring is connected to the distal ends of the blades with portions of the blades projecting both radially inwardly and outwardly of the ring. End edge portions of the blades adjacent to the end wall project radially outwardly beyond the periphery of the end wall and are both tapered backwardly in the opposite axial direction and beveled.
Description (OCR text may contain errors)
tates atet Babb et al.
 CENTRIFUGAL BLOWER  Inventors: Daniel F. Bubb, Grafton; James M.
 Appl. No.: 2,182
[451 Set. 19, 1972 7/1961 Denbo et al. ..4l6/l88 2/1967 Nelson ..416/ 187 Primary ExaminerEverette A. Powell, Jr. Attorney-J. H. Slough  ABSTRACT A centrifugal blower has a frusto-conical end wall with a central hub and a plurality of elongated blades disposed parallel with the hub axis and carried around ;J.E.(l ..416/187, 416/188 the outer periphery f the end n A continuous ring E 'f Id is connected to the distal ends of the blades with por- 0 8 tions of the blades projecting both radially inwardly and outwardly of the ring. End edge portions of the blades adjacent to the end wall project radially out-  References Cited wardly beyond the periphery of the end wall and are UNIT D STATES PATENTS goth tapertcaidb balclwardly in the opposite axial 1,947,658 2/1934 Pizzuto ..416/182 eve e 2,652,190 9/1953 Meltzer et a1 ..4l6/l87 2 Claims, 6 Drawing Figures I I l I I f J J I Q l t l I l j l I j 1 I cnurnrrucxr. nrownn This invention relates to a centrifugal blower or fan and particularly to a blower for use in a small air circulating apparatus such as an automobile heater and air conditioner.
Centrifugal blowers commonly comprise a plurality of generally radially disposed blades arranged circumferentially around a hub whereby upon rotation of the blower, air disposed between the blades is forced outwardly to create an air current. The blades may be elongated in a direction parallel with the axis of the hub and spaced radially outwardly of the hub whereby a negative pressure is created inwardly of the rotating blades and air is drawn into at least one end of the blower to be circulated outwardly through the blades.
The present invention as herein disclosed comprises a centrifugal blower of the above type preferably integrally constructed from a suitable lightweight plastic material incorporating certain structural refinements which provide a more unobstructed air flow, decreases turbulence, increase efficiency of the blades, reduce noise due to undesired eddy currents, and provide increased structural strength over known construction. Elongated blades project parallel with the axis of the blower from the outer peripheral edge of a frusto-conical end wall, the blades being curved about axis parallel with said blower axis and being connected at the distal ends thereof by an integral ring. The blades project radially outwardly beyond the diameter of the end wall and both inwardly and outwardly of the ring. The axially directed end edges of the blades adjacent to and projecting radially beyond the end wall are tapered or angled backwardly in the opposite axial direction and are beveled to provide substantially sharp end edges.
The general object of the invention, therefore is to provide an improved centrifugal blower as set forth above which is quieter and smoother running, creates less turbulence, reduces objectionable eddy currents, and has overall increased efficiency and strength as compared with known blowers of this type.
Other objects of the invention and a number of ad vantages thereof will become apparent from the followin g description of one embodiment of the invention disclosed in the accompanying drawings in which:
FIG. 1 is a top plan view, partially in section, of a preferred embodiment of the centrifugal blower of this invention;
FIG. 2 is a side elevation of the blower; FIG. 3 is a section taken along the line 3-3 of FIG.
FIG. 4 is a bottom plan view of the blower;
FIG. 5 is a fragmentary perspective of a portion of the blower showing the blades as seen from inside the blower; and
FIG. 6 is a fragmentary perspective of a portion of the blower showing the blades as seen from outside the blower.
Referring now to the drawings in all of which like parts are designated by like reference numerals, the centrifugal blower is generally indicated at 10 and is preferably integrally formed from a suitable lightweight plastic. Said blower comprises a generally frusto-conical end wall 11 having a central hub 12 which includes a hub portion 13 projecting inwardly of the blower from the convex side of said wall and a hub portion 14 projecting outwardly of the blower from the concave side of said wall. The hub portion 14 is reinforced by generally triangular, radially directed ribs 18 which are disposed within the concavity of the end wall 11. The hub 12 has a central aperture or opening 15 extending therethrough, said opening being generally circular but having a flattened portion 16 therein whereby the blower is adapted to be mounted upon a drive shaft (not herein shown) having a complementary flat surface portion. It will be readily understood that by means of the hub 12, said blower can be relatively nonrotatably mounted upon a drive shaft (not herein shown) of a suitable motor. The inner end portion 13 is provided with diametrically disposed slots 17 whereby the same is compressible by a suitable clip (not herein shown) or other means for securing the same to the drive shaft.
The blower 10 is provided with a multiplicity of circumferentially evenly spaced, elongated blades 20 which are disposed parallel with the hub axis and are integrally formed adjacent to the outer periphery 1 1 of the end wall 11. As shown in FIG. 3, portions of said blades extend radially outwardly beyond the outer periphery 11', and the inner edges of the blades are curved inwardly at their lower ends to provide fillets 21 which blend smoothly into the upper surface of said end wall. As best seen in FIG. 1, the blades 21 are curved about axes which are parallel with the hub axis and disposed with their concave sides directed generally in the direction of rotation of the blower as indicated by the arrow A.
The distal ends of the blades 20 opposite to the end wall 11 are all integrally connected by a ring 23, said ring being disposed inwardly of the outermost edges of said blades and having an inner diameter slightly larger than the outer periphery of the end wall 11. By providing that the blades 20 protrude outside of the ring 23, a greater mass of material is provided in the ring than that found in known constructions. The present inventors find that this results in an easier flow of plastic material during molding and a stronger ring.
Referring now particularly to FIGS. 2 and 6, the portions of the axially directed end edges of the blades 20 adjacent to the end wall 11 which project outwardly beyond said end wall are tapered or angled backwardly as indicated at 24 in the opposite axial direction and are provided with bevels 25 whereby said end edge portions are relatively sharp. The tapers 24 are such that the end edge portions of the blades are curved or angled backwardly in the direction of the ring 23 beyond the peripheral edge 11'.
Applicants have found that a blower of the form herein described and illustrated substantially meets the objects of the invention by providing improved air flow characteristics resulting in increased efficiency, decreased turbulence, and overall quieter operation.
1. A centrifugal blower of molded plastic construction having a frusto-conical end wall of substantially uniform thickness whereby said wall is generally convex in one axial direction; said end wall having a circular outer peripheral edge portion; a plurality of elongated, circumferentially spaced blades projecting parallel with the axis of said blower in said one direction, said blades curved about axes parallel with and having an outer bevel thereon; the distal ends of said blades being joined by an integral ring, said blades projecting radially inwardly and outwardly of said ring.
2. A centrifugal blower as set forth in claim 1: said ring having an inner diameter greater than the diameter of said end wall.
i i 8 I I