US 3584968 A
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United States Patent Inventor Mowry W. Keith Los Angeles, Calif. Appl. No. 863,975 Filed Oct. 6, 1969 Patented June 15, 1971 Assignee Howard D. Furst El Toro, Calif. a part interest FAN CONSTRUCTION 7 Claims, 5 Drawing Figs.
U.S. C1 415/210, 415/215 Int. Cl 1 04129144, F04d 29/52 Field ofScarch 415/210,
References Cited UNITED STATES PATENTS Seymour, Jr Cline et a1.
Ayers Carlson Carlson Beehler et a1 Carlson Primary Examiner-Henry F. Raduazo Attomey-Lyon and Lyon X ABSTRACT: A fan construction uniquely combining axial and centrifugal fan structures having outer and inner cylinders defining an annular space therebetween, and a generally conoidal rotor providing a conoidal, bladed passageway having a central inlet and a peripheral output communicating with the annular space.
PATENTEU JUH 1 5 I971 SHEET 1 BF 2 INVENTOR MawyM/zzf ATTORN Y PATENIEU JUHI 512m SHEET 2 [IF 2 INVENTOR Mwrry l k/fiwf BRAKE HORSEPOWER STATIC PRESSURE STATIC EFFICIENCY mmzmmmmm AIR VOLUME IN CUBIC FEET PER MINUTE ATTORNEY F AN CONSTRUCTION BACKGROUND OF THE INVENTION While it has been attempted in the past to combined centrifugal and axial flow in a single fan construction, the prior fans have not been entirely satisfactory, usually requiring relatively large space, delivering turbulent or spinning air, being relatively noisy and unstable in performance. The latter problem of stabilityhas been particularly acute, in that most prior fan constructions operate on a peaking pressure curve which subjects the fan to pulsation or hunting.
SUMMARY OF THE INVENTION Accordingly, it is an important object of the present invention to provide a highly improved fan construction which effects substantially savings in space over prior fans of comparable rating.
It is another object of the present invention to provide a fan construction of the type described wherein discharge air moves in a substantially straight path, devoid of spin to eliminate pulsation or surging, and greatly reduce noise levels.
The fan construction of the instant invention further provides high stability in performance, having a constantly rising pressure curve from wide open to block tight, without a stall point, to eliminate the pulsation or hunting or prior fans having a peaking pressure curve.
It is still another object of the present invention to provide a fan construction having the advantageous characteristic mentioned in the preceding paragraphs, which is extremely simple in construction, easily installed in an in-line relation, and which is durable and reliable throughout a long useful life.
Other objects of the present invention will become apparent upon reading the following specification an referring to the accompanying drawings, which form a material part of this disclosure.
The invention accordingly consists in the feature of construction, combinations of elements, and arrangements of parts, which will be exemplified in the construction hereinafter described, and of which the scope will be indicated by the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a top plan view, partly broken away, showing a fan constructed in accordance with the teachings of the present invention.
FIG. 2 is a longitudinal sectional elevational view taken generally along the line 2-2 of FIG.
FIG. 3 is an inlet-end view of the fan of FIG. 1, partly broken away.
FIG. 4 is an outlet-end view of the fan of FIG. 1.
FIG. 5 is a graph illustrating operating characteristics of the instant fan.
Referring now more particularly to the drawings, and specifically to FIGS. 1 and 2 thereof, an open-ended outer cylinder or housing 11 is provided at its inlet end 12 with a circumferentially extending mounting flange 13, and at its outlet end 14 with a circumferentially extending mounting flange 15.
An inner tube or cylinder 18, ofa length and diameter considerably less than that of the outer cylinder 11, is arranged within the latter coaxially therewith and adjacent to the outlet end 14 so as to be spaced from the inlet end 12. The inner cylinder 18 is fixed coaxially within the outer cylinder 11 by any suitable mounting means, and the inner cylinder is provided at its leading end 19 with a peripheral reinforcing flange 20, having a peripheral reinforcing flange 21 at its trailing end 22. Interiorly ofthe fixed inner cylinder 18, axially thereofis a shaft 23 journaled in longitudinally spaced pillow blocks 24 and 25 respectively mounted on generally horizontal channel members 26 and 27 extending chordally across and suitably fixed interiorly ofthe inner cylinder.
At the rear or outlet end of the rotary shaft 23 may be provided a transmission member or pulley 28; and, suitable drive means such as a motor 29 may be superposed exteriorly on the housing 11 and carrying a drive member or pulley 30 located over the pulley 28. A transmission member or belt 31 may be trained about the pulleys 28 and 30, extending therebetween through a tubular guard 32 opening at it opposite ends to the interior ofinner cylinder 18 and exterior of housing 11.
As the inner cylinder 18 is located in spaced relation concentrically within the housing 11, there is defined therebetween an annular space 34 having its opposite ends open. The tubular guard 32 extends generally radially through the annular space 34.
The shaft 23 projects forward beyond the end 19 of inner cylinder 18, as at 35, where it carries a hub 41 located in the space between the ends 19 and 12 of respective inner and outer cylinders 18 and 11. The hub 41 may be of generally conoidal configuration, having a generally circular backplate 42 ofa diameter approximately equal to and slightly greater than the external diameter of inner cylinder 18 and concentrically keyed to the shaft end 35 adjacent to the inner-cylinder end 19. From the periphery of backplate or wall 42 extends a generally conoidal wall 43 tapering toward and terminating short of the housing end 12 in an externally convex smaller end or nose 39. The cone angle of the conoidal surface 43 is approximately 45", so that the walls 43 and 42 also define an included angle of approximately 45.
A plurality of blades 36 are carried by the hub 41, extending along and projecting outward from the conoidal wall 43. Each blade 36 may be substantially straight or slightly arcuate and extends generally spirally about the axis of the conoidal hub. More particularly the blades 36 are each of generally helical configuration, defining a segment of a helix of approximately 45 pitch and of increasing diameter at an angle of approximately 45 to the helix axis. Thus, each blade 36 extends oblique to both the hub axis and direction of hub rotation, being skew to the hub axis and disposed at angles of approximately 45 to both a plane normal to the hub axis and a plane longitudinally of and through the hub axis.
In addition, each blade 36 is configurated with its leading edge 37 and trailing edge 38 on lines passing through the hub axis. This is best seen in the end views of FIG. 3. Also illustrated therein is the airfoil configuration of each blade 36, having a rounded leading edge 37 and tapering therefrom to a feathered trailing edge 38.
Conformable and spacedly surrounding the conoidal hub 41 is a generally conical shroud 45. The shroud 45 is spacedly circumposed about the hub and extends proximate to the extremities of the blade 36, being fixedly secured thereto by any suitable means. The conical angle of the shroud 45 may be substantially equal to or somewhat less than that of the hub 41, terminating at a larger end 46 adjacent to the trailing or discharge edges 38 of the blades36, and having its smaller end formed with a circumferentially extending, out-turned lip 47. The shroud 45 thus combines with the hub wall 43 to define therebetween an annular passageway 48 of increasing diameter in the direction from the housing inlet end 12 toward the housing outlet end 14.
A tapering air receiver or inlet cone 40 of generally annular configuration has its inlet end flared, as at 51 and provided a circumferential lip 52 secured in position extending about the interior of outer cylinder 11 adjacent to the inlet end thereof. From the inlet end 12, the inlet cone extends into the cylinder 11, being of convergent configuration and has its inner end 53 extending closely within the lip 47 of shroud 45.
An air passageway is thus defined inward through the inlet cone 50 centrally of the housing 11, thence in diverging rela-,
18 and extend radially therebetween for fixed securement thereto, as by welding or other suitable means. Each vane 55 includes a forward or inlet portion 56 of arcuate configuration, substantially 45 of a circular arc and having its leading edge 57 proximate to the end 19 of cylinder 18. The leading edge 57 of each vane 55 is advantageously disposed at an angle of approximately 45 to a radial plane of the cylinder axis. At the inward end of the arcuate vane portion 56, the vane continues tangentially to the arcuate portion and in substantial parallelism with the cylinder axis, lying in a radial plane of the latter, as at 58, terminating in a trailing edge 59 medially between the ends of inner cylinder 18.
in operation, upon rotation of shaft 23 by motor 29, the hub 41 and its blades 36 and shroud 45 are caused to rotate and move air inward centrally through the housing end 12 and inlet cone 50. The air is then spiraled through the passageway 48 of shroud 45 and cone 51 emerging at the larger end thereof for entry into the space 34 between vanes 55. Air movement progresses between the vanes 55 where it is straightened or caused to move longitudinally of the cylinder axis and outward through the cylinder end 14.
From the chart of FIG. 5, it will be appreciated that the static-pressure curve of the instant fan is of a continuously increasing character, having no peaks, and therefore eliminating the pulsation or hunting, and possible stalling of prior fan constructions. Also, the horsepower curve illustrates that the instant fan has a true nonoverloading horsepower characteristic, which assures a self-limiting horsepower requirement reaching its maximum in the normal range of operation.
While the above-described angular relationships ofconoidal hub 41, blades 36, shroud 45 and vanes 55 have been found to be optimum for efficiency and air-handling volume, the angles may be varied within a range of about l and retain the advantages herein. However, it is noted the leading and trailing edges of the blades 36 are most advantageously arranged with extensions thereof passing through the cylinder axis, deviation from this limitation being detrimental to performance and efficiency.
From the foregoing, it is seen that the present invention provides a fan construction which fully accomplishes its intended objects and its well adapted to meet practical conditions of manufacture, installation and use.
Although the present invention has been described in some detail by way of illustration and example for purposes of clarity of understanding, it is understood that certain changes an modifications may be made within the spirit of the invention.
What 1 claim is:
1. A fan construction comprising an open-ended outer cylinder having inlet and outlet ends, an open-ended inner cylinder fixedly mounted in spaced relation axially within said outer cylinder spaced from the inlet end thereof a generally conoidal hub having a maximum diameter approximately equal to that of said inner cylinder and joumaled axially within said outer cylinder adjacent to said inner cylinder and tapering toward said inlet end, a plurality of air-foiled blades carried by said hub for rotation therewith and each extending along the hub surface at an angle oblique to the hub axis and direction of hub rotation, a conical shroud circumposed spacedly about said hub proximate to the extremities of said blades for rotation therewith and combining with said hub to define an annular passageway of increasing diameter in the direction from said inlet end to the space between said cylinders, said blades serving to move air in said inlet end through said annular passageway and into the annular space between said cylinders, guide vanes in said annular space each extending arcuately away from said passageway and thence tangentially in substantial parallelism with the axis of said cylinders, and an inlet cone fixed in the inlet end of said outer cylinder and tapering inwardly toward said shroud, said inlet cone terminating at its inner end within said shroud, for conducting air to said passageway with minimum leakage between said cone and zg y- 2. fan construction according to claim 1, said guide vanes each having its leading edge disposed obliquely to the cylinder axis, an said blades each having their leading and trailing edges in planes generally radial to the cylinder axis.
3. A fan construction according to claim 1, said blades each extending at an angle approximately 45 to a radial plane of the cylinder axis.
4. A fan according to claim 1, said blades each extending at tan angle approximately 45 to the cylinder axis.
5. A fan construction according to claim 1, said blades each extending skew to the cylinder axis at angle of approximately 45 to each of a pair of radial planes of the cylinder axis spaced apart.
6. A fan construction according to claim 1, said guide vanes extending arcuately through an arc of approximately 90 and thence tangentially in said parallel relation.
7. A fan construction according to claim 6, said blades comprising approximately 8 in number and each extending generally spirally about the cylindrical axis at angles of approximately 45 to planes both radial and normal to the cylinder axis.