US 2628018 A
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Feb. 10, 1953 G. H. KOCH AIR TRANSLATING APPARATUS 2 SHEETS-SHEET 1 Filed April 13, 1950 INVENTOR H C 0 K H V A T s U G G. H. KOCH AIR TRANSLATING APPARATUS Feb. 10, 1953 2 SHEETSSHEET 2 Filed April 13, 1950 FIG. 3,
INVENTOR GUSTAV H. KOCH WITSIESSES: aw. Lam h fiEvululi-w ATTORNEY in cross-sections to axial lines.
Patented Feb. 10, 1953 a UNITED STATES PATENT OFFICE AIR TRANSLATING APPARATUS Gustav H. Koch, Springfield, Mass., assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application April 13, 1950, Serial No. 155,587
14 Claims. (Cl. 230-259) This invention relates to air circulating units, and relates more particularly to so-called radial discharge type, floor fans which have motors supported small distances above horizontal surfaces such as floors of rooms, and which have propeller blades rotatable by the motors about vertical axes.
In a propeller fan of the type most commonly used for circulating air in a room, such as a socalled deskfan, a substantial volume of the air moved by the fan is drawn radially inwardly at 1 the tips ofthe fan blades, and has its radial direction changed into an axial direction for discharge from the fan, when it mixes with the air drawn axially from the rear of the fan. The velocities of the radially and axially moving air streams are reduced when they mix, and this results in a reduction in the volume of air flow or capacity of the fan.
It has been found possible to increase the air flow in a fan of the type which is supported by a pedestal a substantial distance above a floor, and arranged to discharge horizontally, by encompassing the fan with spaced, curved, shroud rings which effect a change of about 90 in direction of the air moving radially towards the tips of the fan blades, before it reaches the blade operating zone. The entering edges of such shroud rings are substantially tangent, in cross-sections, to radial lines and their trailing edges are tangent The use of such shroud rings is disclosed in my copending application, Serial No. 768,686, filed August 14, 1947.
'The use of such shroud rings has greatly increased the volume ofair flow or capacity of such 'p'edestal-mountedfans. However, in applying I such shroud rings to a vertical axis, radial discharge type floor fan, there is a reduction in air flow as the lowermost shroud ring is brought close 1 to the floor.
This is thought to be due to the blocking by such horizontal surface of the axial inlet of such fan.
shroud rings of this invention differ, however, from the above-mentioned shroud rings in that the trailing or air leaving edges are slightly in- 2 a clined toward the center or axis of the fan; that is, the cross-section of the trailing edge is tangent to a line disposed at a slight angle to the axis. The purpose of this angle is to increase the passage between adjacent shroud rings and thereby to compensate for the reduction in air flow effected by obstructing the axial inlet by the floor or horizontal supporting surface.
Another and more specific object or feature of the invention is to provide shroud rings around the propeller blades of radial discharge type, floor fans, which have curved trailing edges with crosssections which are tangent to lines extending at a slight angle, such as 5 to 20, to the axis.
The invention will now be described with reference to the drawing, of which:
Fig. 1 is a perspective, side elevational view of a radial discharge type, floor fan embodying this invention;
Fig. 2 is a sectional View along the lines II-II of Fig. 1;
Fig. 3 is a diagrammatic view illustrating the flow of air into, through and from the fan; and
Fig. 4 is an enlarged view, partially in section, of adjacent shroud rings used.
The fan illustrated by the drawing is a socalled, radial discharge type floor fan although, of course, it could be supported on other horizontal surfaces than floors. It comprises an electric motor l0 supported by the rods II and [2 from the three, vertically extending metal legs l3, curved in cross-section, the lower ends of which are fitted in the plastic foot members I4 which are supported on the horizontal surface 30. The motor has a vertical shaft extending thereabove to which are attached the propeller fan blades l5. The legs l3 have outwardly turned upper ends to which are attached the lower ends of the vertically extending rods IS, the upper ends of which are turned over as hooks on which the cover I! is seated. The cover has the downwardly extending straps [8 attached to its lower surface and through which a bolt l9 extends and which supports the inverted conical, air deflector 20. The rods l6 and other rods 2| which are spaced therebetween, support the spaced guard rings 3| between which the air deflected by the deflector 20 passes as it is discharged from the fan.
The shroud rings 22, 23, 24 and 25, each may be rolled from strip stock so as to have a central body portion a curved in cross-section in a circular arc, terminating in an upper end I) of minimum diameter and in a lower end 0 of maximum diameter, the latter being curved inwardly in cross-section in substantially a circular are. It
will be noted that the curved central body portion a. extends first substantially radially inwardly adjacent the lower end 0, although at a small angle upwardly therefrom, and then gradually turns to axially forwardly or upwardly, although again at a small angle e to a line parallel to the axis, such as an angle of 5 to In the illustrated embodiment the angle is 16.
The shroud rings extend concentrically around, and are supported by, the legs l3, and their upper ends, at the legs, are shaped atdto lie against the legs to which they are attached as by spot welding. The upper ends of the shroud rings between the leg contacting portions dhave crosssections which, as illustrated by Fig. 4, aretangent to lines extending from 5 to20. from vertical, axial lines. In the illustrated embodiment, the upper, air leaving edge of each lower shroud ring is disposed a small distance, about inch, below the air entering edge of the adjacent upper ring. This spacing should be very small, less than one-fourth. of the space between the planes of the inlet and outlet edges of one shroud ring, and recent tests indicate that the best results may be expected when this space is reduced to zero.
The uppermost shroud ring extends around the upper portion of the space swept by the propeller blades, while the adjacent ring 24 extends around the. lower portion of the space swept by the blades. The shroud rings 23 and 22 extend around the space below the blades and between same and the foot: members it of the fan. The shroud rings are arranged concentrically around the axis of the fan and are. spaced equal distan'ces apart.
In operation, with reference to Fig. 3 of the drawing, when the fan blades 15 are rotated by the motor ill, the axial inlet to the fan is blocked by the surface upon which the fan is supported, so that the air can only enter the fan in radial directions. In Fig. 3, arrows have been placed to indicate, as nearly as possible, the directions of air movement observed in the operation of the fan shown on the drawings. The lengths of the arrows are in a general way, proportional to the volumes of air in motion at the various inlet points. The shroud rings turn the air that enters between adjacent shroud rings and that which strikes the uppermost shroud 25, from radially inwardly to directions which are substantially axially forwardly or upwardly but which extend slightly inwardly toward the center or axis of the fan. Therefore, as the air approaches the conical deflector 20, it is moving substantially in an axial stream. The deflector 20 then turns the air outwardly for discharge into the spaces served by the fan.
It will be noted that there is substantial inlet area for admission of air between the lowermost shroud ring 22 and the surface 36. However, the air cannot enter as freely as if the entire inlet face were open to the atmosphere and the air could enter freely in axial direction. This is compensated for by disposing the air leaving edges of the shroud rings at a slight angle toward the center of the fan, thereby providing for greater admission of air between the shroud rings than is provided in the arrangement shown in my prior application Serial No. 768,686, in which such air leaving edges are disposed in directions parallel to the axis.
The illustrated embodiment represents a fan in which my invention has been reduced to practice. It is a 10-inch fan; that is, the diameter of the fan blades is 10 inches. In this embodiment, the central body portion a of each shroud ring is curved in cross-section in a circular arc of one and 5% inch radius. The plane of the outlet or air leaving edge of each shroud ring is spaced 1% inches from the inlet or air entering edge of the same shroud ring and inch from the entering or air inlet edge of the next shroud ring. The upper end b is disposed at an angle of 16 degrees to a line parallel to the axis.
While I have shown my invention in but one form, it will be obvious to those skilled in the art that it is not so limited, but is susceptible of various other changes and modifications without departing from the spirit thereof.
What I claim is:
l. A ventilating unit comprising a support adapted to rest upon a horizontal top surface, a vertical shaft rotatably mounted on said support, propel er fan blades mounted on said shaft for rotation therewith and operable to direct air upwardly. and a plurality of shroud rings arranged concentrically around said blades, each of said rings having a concave curved outer surface extendin first ra ially inwardly and then curved to axially forwardly or upwardly at a small angle to the axis of rotation of said blades.
2. A ventilating unit as set forth in claim 1 in which the spacing between adjacent shroud rings is less than one-fourth the distance between the planes of the inlet and outlet edges of one shroud ring.
3. A ventilating unit comprising a motor having a rotary shaft extending vertically thereacove, propeller fan blades secured to said shaft for rotation therewith and operable. to direct air upwardly, means for supporting said motor upon a lower, horizontal surface, and a plurality of shroud rings arranged concentrically around said blades and motor, each of said rings having an outer edge of maximum diameter and a concave curved outer surface extending inwardly and upwardly from said edge and terminating in an inner edge which istangent in cross-sections to lines extending at angles not less than 5 and not greater than 20 to vertically extending lines.
4. A ventilating unit as claimed in claim 3 in which the outer edges of the shroud rings are curved downwardly and inwardly.
5. A ventilating unit as claimed in claim 3 in which the inner edge of each lower shroud ring is spaced below the outer edge or the adjacent upper shroudring a distance less than one-fourth the distance between the planes of the inlet and outlet edges of one shroud ring.
6. A ventilating unit as claimed in claim 3 in which the outer edges of the shroud rings are curved downwardly and inwardly, and in which the inner edge of each lower shroud ring is spaced below the outer edge of the adjacent upper shroud ring a distance less than onefourth the distance between the planes of the inlet and outlet edges of on shroud ring.
7. A ventilating unit comprising a motor having a rotary shaft extending vertically thereabove, propeller fan blades secured to said shaft for rotation therewith, spaced vertically extending legs for supporting said motor upon a lower horizontal surface, and a plurality of shroud rings arranged concentrically around said blades and motor, each of said rings having an outer edge of maximum diameter and acurved surface extending inwardly and upwardly from said edge and terminating in an inner edge which at said legs, lies against and is secured thereto, and between said legs is tangent in cross-sections to lines extending at angles not less than 5 and not greater than 20 to vertical lines.
8. A ventilating unit as claimed in claim 7 in which the outer edges of the shroud rings are curved downwardly and inwardly.
9. A ventilating unit as claimed in claim 7 in which the inner edge of each lower shroud ring is spaced below the outer edg of the adjacent upper shroud ring a distance less than one-fourth the distance between the planes of the inlet and outlet edges of one shroud ring.
10. A ventilating unit as claimed in claim 7 in which the outer edges of the shroud rings are curved downwardly and inwardly, and in which the inner edge of each lower shroud ring is spaced below the outer edge of the adjacent upper shroud ring a distance less than one-fourth the distance between the planes of the inlet and outlet edges of one shroud ring.
11. Th combination with a propeller fan operable to direct air forwardly, of a shroud assemoly therefor having radial and axial inlets and designed for operation with its axial inlet blocked, said shroud assembly comprising a plurality of concentric, axially displaced, shroud rings, each of said rings having an outer edge of maximum diameter and a concave curved outer surface extending inwardly and forwardly from said edge and terminating in an inner edge which is tangent in cross-sections to lines extending at not less than 5 and not more than 20 to lines parallel to the common axis of said rings.
12. A shroud assembly as claimed in claim 11 in which the outer edges of the shroud rings are curved inwardly and rearwardly.
shroud assembly as claimed in claim 11 in which the inner edge of each rearward shroud REFERENCES orrEn The following references are of record in the file of this patent:
UNITED STATES PATENTS Number Name Date 1,889,567 Persons Nov. 29, 1932 2310.772 Fukal Feb. 9, 1943