US 3251540 A
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Description (OCR text may contain errors)
May 17, 1966 D. D. KINSWORTHY 3,251,540
AIR MOVING DEVICE Filed Deo. 17, 1963 2 Sheets-Sheet 1 INVENTOR. DONALD D. KINSWORTHY ATTORNEYS May 17, 1966 D` D. KINSWORTHY AIR MOVING DEVICE 2 Sheets-Sheet 2 Filed Dec. 17, 1963 INVENTOR. KINSWORTHY DONALD D.
ATTORNES United States Patent C 3,251,540 v AIR MOVING DEVICE Donald l). Kinsworthy, Dayton, Ohio, assignor to The Lau Blower Company, Dayton, Ohio, a corporation of (Ehio uned nee. 17, 1963, ser. No. 331,140 1 Claim. (Cl. 2311-117) This invention relates to a blower assembly, and particularly to a blower of the transverse or tangential flow type.
fBlower assemblies which utilize a blower wheel and a cooperating housing to draw air radially between the blades on one side of the scroll and force the air outwardly therefrom between the blades at some other point in the blower wheel are termed cross-110W, transverse, or tangential blowers, and for the pu-rposes of discussion herein these blower wheels will be designated tangential blower wheels. The advantages of such a blower include the capability of producing high static pressures, and their compact size which enables use in relatively thin heating or cooling units wherein it is not feasible or desirable to draw the air axially into the blower wheel as required in conventional centrifugal blower wheels. In a blower unit using a tangential blower wheel, both the inlet and outlet are substantially tangential to the wheel, whereas in a conventional centrifugal type blower wheel there is an -axial inlet and a radial outlet. The capacity of the blower wheel is thus limited to the size of the inlet which is proportioned to the diameter of the blower wheel, so that a high capacity air conditioning unit requires a com.- paratively thick cabinet. In a tangential blower wheel the capacity is increased merely by increasing the axial length thereof with any consequent changevin the thickness of the associated unit or its cabinet.
However, these tangential blowers are not without serious disadvantages, for example, the relatively simple designs disclosed in the United States patents of Anderson No. 1,838,169, issued December 29, 1931, No. 1,886,- 513, issued November 8, 1932, and No. 1,920,953, issued August 8, 1933, never became commercially successful -since their apparent capacity was low and their performance varied measurably for slight changes in speed. Several recent developments are disclosed in the United States patents to Eck Re. No. 25,236, issued April 2, 1963, and Coester No. 3,033,441, issued May 8, 1962 and Re. 25,409, issued July 2, 1963. Each of these designs has a complex housing structure which is highly sensitive to dimensional changes thus resulting in a very expensive blower substantially incapable of low cost mass production.
Accordingly, an important object of this invention is to provide an improved and simplified tangential blower assembly which is not subject to the aforesaid disadvantages and can be mass produced at a relatively low cost without any substantial loss in operating efficiency.
Another object of this invention is to provide a blower assembly of the transverse type wherein the blower is simple in design and easily manufactured from sheet metal, plastic, or other thin materials, and particularly to provide such an assembly wherein an efiicient conversion from velocity to static pressure is eifected in the housing adjacent the blower wheel so that the length of the outlet portion of the housing is held to a minimum.
A further object of this invention is to provide a compact tangential blower wheel assembly which can be constructed in substantially any length as required to produce the particular volume desired, and particularly to provide a blower assembly of the aforesaid type which does not require a complex housing having close tolice erances or structure which induces a vortex inside the blower wheel.
Additional objects and advantages of the invention will be apparent from the following description, the accompanying drawings and the appended claims.
In the drawings- FIG. 1 is a perspective view of a typical air conditioning unit embodying a tangential blower in accordance with the invention;
FIG. 2 is a vertical -section View through the air conditioning unit shown in FIG. 1;
FIG. 3 is a perspective illustration of a blower assembly in accordance with the invention;
FIG. 4 is a front elevation view of the assembly shown in FIG. 1;
FIG. 5 is a sectional view taken essentially along the line 5-5 of FIG. 4;
FIG. 6 is an enlarged sectional view of one of the blades of the blower wheel; and
FIG. 7 is another enlarged sectional view of the rear edge of the outlet duct cover.
Referring to the drawings wherein a preferred embodiment of the invention is shown, FIG. 1 illustrates a typical air conditioning unit 10 having an inlet opening 11 in the vertical front wall 12 thereof and an -outlet opening 13 in the top wall 14 thereof. As seen in FIG. 2, a tangential blower assembly 15 in accordance with the invention is mounted within the air conditioning unit 10. The air is drawn through the grilled inlet opening 11 of the unit 10, through a removable filter 17 mounted in the unit immediately ahead of the cooling coils 1S, After the air then passes over the cooling coils 18, it ows into the blower housing 20 through the inlet 21, and is drawn between the individual blades 22 and into the interior chamber 24 of the tangential blower wheel 2S. The blower wheel 25 subsequently forces the air from the chamber 24 into a curved expansion cone 27 created between the blower wheel 25 and the housing 20 for converting the velocity pressure to static pressure. The air then ows through the outlet duct 28 which denes the large end of the expansion cone 20, over the heating coils 30, through the outlet passageway 31 defined in the air conditioning unit, and then upwardly through the grilled outlet opening 13.
The blower housing 20 is held securely in the unit 10 with the edge 33 of its inlet 21 resting on the lower |wall 34 of the housing, and with the wall 35 of the outlet duct 2S resting on the diagonal support `baffle 36. In addition, the housing 20 may be held positioned in contact with the top and back walls 14 and 37 of the unit 10 by suitable brackets, not shown, mounted between the unit It) and the blower assembly 15 so that the housing 2t) is held securely in the air conditioning unit.
The unit 1t) has suitable conventional controls and associated equipment provided for selective control of the cooling and heating coils 18 and 30, so that the unit 10 can be used as a heating yor cooling unit, or merely as a ventilation unit if desired. The various walls and support components of the unit l@ are preferably insulated as shown to insure quiet operation and maximum heating or cooling of the air flowing through the blower assembly 15.
FIG. 3 illustrates in more detail the tangential blower assembly 15 separated from the unit 1t) including the housing 20 having the elongated blower wheel 25 mounted for rotation therein and driven by the motor 41. The housing 2t) includes aback wall 42 which is volute shaped and extends from the rolled edge 33 substantially directly above the axis of the blower wheel 25 and to the point 44 (FIG. 5) where the volute or spiral curve terminates in the integral lower wall 42a of the outlet duct 28. The
the blower wheel 25 thus define the diffusion cone 27 of l gradually increasing width which is an approximation of a logarithmic spiral and extends from a plane through the edge 33 to the -outlet 61, as will be explained.
The ends of the housing 20 are closed by the fiat end walls 45 and 46 Iwhich are divided into the spiral portions 47 and 48 and the outlet duct portions 51 and 52, respectively. The spiral portions 47 and 48 form the ends of the 'chamber enclosing the blower wheel 25 whereas the outlet portions 51 and 52 define the side walls of the outlet duct 27. The back wall 42 and the end walls 45 and 46 are secured together by any substantially rigid and conventional fluid tight expedients, e.g., lby deforming the side edges of the back wall 42 over and into contact with the end walls 45 and 46 and then brazing or spot welding these members together.
An important feature of the invention lies in the position of the flat top wall member 35 which forms the upper Iboundary of the outlet duct 27 and which extends between substantially Huid tight and rigid connections with the upper edges of the outlet portions 51 and 52 of the side walls 45 and 46. The rear edge 55 of this top wall 35 is rolled similarly to the edge 33, and is also closely spaced from the outer periphery of the blower wheel 25. The front edge 57 of the wall 35 forms the upper periphery of the outlet opening 58 from the duct 27.
The rectangular inlet 21 is thus defined by the rolled edge 55 of the t-op wall 35, the peripheral edges of the spiral portions 47 and 48, and the upper edge 33 of the back wall 42. On the other hand, the rectangular outlet 58 is defined by the forward edge 57 of the top plate 35, the vertical edges 60 and 61 of the outlet portions 51 and 52 of the side Walls, and the front edge 63 of the lower wall 42a.
The elongated blower 'wheel 25 includes a plurality of parallel and circumferentially disposed blades 22 each of which has its opposite ends 64 secured to one of the end plates 65. The blades may be brazed to the end plates,
67 secured rigidly thereto which in turn releasably receives the drive shaft 68 of the motor 41 secured on the outer surface of the side wall 45. The right-hand end plate 65 has a similar hub 70 secured thereto for receiving the support shaft 71 which extends through an opening in the side Wall 46. The right end of the shaft 71 is received and supported by the bearing member 73, e.g., a roller or other suitable anti-friction bearing, which is held in place on the side lwall 46 by the retainer 74.
As seen in FIG. 6, the sheet metal blades 22 have smoothly curved surfaces, which have a center of curvature at the point 75, and preferably suicient blade surface to allow the leading edge 76 thereof to have an angle of attack a of about 25 to 30, Whereas the trailing edge 78 extends substantially radially of the blower wheel 25. This provides for maximum scooping action to draw the air into the interior chamber of the blower, as well as smooth outward flow in the opposite direction.
Another important feature of thisinvention is that the axial length of the housing 20 and blower wheel 25 may be varied to achieve the desired air output rates. When the axial length of the assembly 15 Ais increased it may be necessary to reinforce the housing 20 to maintain rigidity thereof, and this can be accomplished by securing `braces to the outside of the housing since it is undesirable to 4obstruct the smooth inner configuration of the housing 20.4 The horizontal edges 33 and 55 of the inlet 21 are rolled to add rigidity to the housing and insure that the precise configuration of the opening 21 will remain constant. The blower wheel 25 may be strengthened by adding support disks or bulkheads, for example, of the types which are used in a double inlet centrifugal blower wheel axially along its length.
As indicated above, the housing 20 and the blower wheel 25 define therebetween a gradually enlarging cone 27 that starts between the edge 33 and the adjacent periphery of the blower wheel 25, and extends through a curved path between the inside surface of the back wall 42 and the blower wheel 25. This cone continues through the outlet duct 28 whose top wall 35 is upwardly tapered, and thus provides for the smooth conversion of velocity pressure to usable static pressure in a compact space.
As seen in FIG. 7, the rear edge 55 of the top wall 35 is placed as close as possible to the periphery of the blower wheel 25 without contact therebetween so that the inlet 21 and outlet 58 are effectively separated. In practice it is found that a slight distance must be placed between the edge 55 and the blower wheel 25 so that the noise level created thereby lis held -to a minimum. The rolled rear edge 55 also aids in reducing the noise created as the blades 22 pass at high speed close to this edge.
During the operation of this blower assembly the motor 41 rotates the blower wheel 25 at a relatively high speed and in a counterclockwise direction as viewed in FIG. 5. This rotation causes air to be drawn through the inlet 21 between the blades 22 and into the internal chamber 24 of the blower wheel 25. The air continues to Iflow across the internal chamber 24 and then outwardly between the ybla-des 22 opposite the inlet 21. The air leaving the 'blades enters the curved cone which extends from the edge 33 and gradually increases in width until it reaches the outlet 58 thus causing a gradual diffusion of the air and a highly efiicient conversion of the velocity pressure to the static pressure. Since the curved cone extends entirely around the blower wheel 25, except for the inlet 21, the pressure conversion is accomplished by the time the air reaches the outlet 5S, thus requiring only a short outlet duct 28 and consequently a compact and very simple housing.
The housing 20 is constructed .from any material capable of providing the necessary strength, as well as providing theability to be shaped into the configuration shown. Thus it is possible to use sheet metal, plastics, or a l combination thereof to construct the housing. While the blower wheel is easily constructed as outlined above, it is Within the scope of the invention to likewise construct it from any suitable material capable of being formed into the desired shapes and of fulfilling the above described functional requirements.
The invention has provided a tangential or transverse blower assembly which is simple in design and is easily mass produced from a variety of materials. The assembly does not require complex structurel in order to induce a vortex within the blower wheel, and it has been found that the length of the blower wheel can be varied from a short length to a very long length. -In addition, the unit can be installed in a minimum of space and the inlet and outlet are parallel and do not require the usual ninety degrees offset therebetween.
While the form of apparatus herein described constitutes a preferred embodiment of the invention, it is to be understood that the invention is not limited to this precise form of apparatus, and that changes may be made therein without departing from the scope of the invention which is defined in the appended claim.
What is claimed is:
A tangential air moving device of the character described comprising, a housing having a tangential blower blower wheel, said back wall extending around said wheel at a gradually increasing distance from the axis of said blower wheel and terminating in a at bottom wall of a rectangular unobstructed outlet opening below said blower wheel, said outlet opening being spaced approximately 270 from said upper edge of said housing, said housing including at sheet metal closed end walls having spiral portions which enclose the ends of said back wall and outlet portions which define the opposite side walls of said rectangular outlet opening, a at upper wall of sheet metal on said outlet portion of said side walls clening the upperboundary of said rectangular outlet opening, said side walls being the sole support for said blower wheel, lsaid upper wall having an upstream edge closely spaced from the outer periphery of said blower wheel, said upper edge of said back wall and said upstream edge of said upper wall defining a rectangular inlet opening of approximately 90 over the circumference of said blower wheel, said blower wheel including a plurality of spaced elongated forwardly curved blades having an angle of attack with a tangent to said Wheel of about 25 and having trailing edge portions which extend radially of said blower'wheel for smooth flow of air between said blades into and from said blower wheel, said blades dening an unobstructed cylindrical chamber internally of said blower Wheel for the free ow of air therethrough, a drive motor secured to one of said end walls for rotating said blower wheel at high speed, said housing and blower cooperating -with said outlet opening to dene a curved and unobstructed expansion chamber which gradually increases in volume and which commences substantially at said top edge of said back wall and terminates at said outlet opening for causing a gradual diffusion of the velocity pressure created by said blower wheel to effect efficient conversion thereof to static pressure.
OTHER REFERENCES German printed application No. 11,074,816, February 1960.
SAMUEL LEVINE, Primary Examiner.
HENRY F. RADUAZO, Examiner.