US20080253896A1

Movatterモバイル変換

Info

Publication number: US20080253896A1
Application number: US11/786,816
Authority: US
Inventors: Gary C. Walls
Original assignee: Individual
Current assignee: Individual
Priority date: 2007-04-13
Filing date: 2007-04-13
Publication date: 2008-10-16
Also published as: WO2008127611A1

Abstract

Fan blades are provided that increase aerodynamic and operational efficiency, and which include baffle elements positioned on the distal ends of the fan blades. The baffle elements operate by shearing blade tip vortices, thereby minimizing turbulent fluid effects, and further providing fluid shunt that imparts a radial velocity component to the fluid. The baffle elements produce a more focused and collimated fluid flow perpendicular to the plane of rotation during forward rotation, and produce a more diffuse, radially-outward directed fluid flow during reverse rotation. The baffle elements are positioned such that they are characterized by a first angle with respect to the radial axis of the fan blade and a second angle with respect to the low pressure surface of the fan blade.

Description

TECHNICAL FIELD

The present invention relates generally to fan blades and, more particularly, to fan blades with airflow-directing baffle elements disposed thereon.

BACKGROUND OF THE INVENTION

The purpose of a fan is to move fluid continuously against moderate pressures. As used herein, the term fluid is intended to indicate material in a liquid, gaseous or vapor state. Accordingly, fan operation is highly dependent upon the total static pressure generated to overcome ambient fluid pressures and create fluid flow. An operating fan produces a pressure rise across the unit because the rotating fan blades function as aerofoils.

A moving aerofoil is essentially a flat plate inclined at an angle and moving through air or other fluids. The aerofoil experiences a force exerted thereon, which is resolvable to a component parallel to the direction of motion (drag) and a component perpendicular to the direction of motion (lift). In a fan, the rotating fan blades experience drag in the direction opposite that of rotation, and experience lift perpendicular to the plane of rotation. The lift forces produced on the high pressure surface of the aerofoil fan blade generate a discharge pressure that results in volume flow of fluid from the surface.

The performance of a fan in terms of pressure, volume flow, fluid velocity, power, and efficiency depends on a number of factors, the most critical of which are:

(a) the design and type of fan;
(b) the size of the fan;
(c) the speed of rotation of the fan impeller;
(d) the condition of the fluid passing through the fan; and
(e) the geometry of the fan blades comprising the impeller.
Consequently, it is a goal of fan design to develop fan blade geometries that optimize operating characteristics and performance.

There are four common types of fans: centrifugal fans, cross-flow fans, propeller fans, and axial-flow fans. As used herein, the term “impeller” or “fan impeller” is intended to indicate a rotating set of blades designed to impart motion to a mass of fluid. Centrifugal, or radial-flow, fans include an impeller running in a casing having a spirally shaped contour. The fluid enters the impeller in an axial direction and is discharged at the periphery, with the impeller rotation being toward the casing outlet. The amount of work done on the fluid, evident in the pressure development of the fan, depends primarily on the angle of the fan blades with respect to the direction of rotation at the periphery of the impeller. Three main forms of blades are commonly: (1) backward bladed, in which the blade tips incline away from the direction of rotation; (2) radial bladed, where the blade tips are radially disposed; and (3) forward curved, where the blade tips incline toward the direction of rotation.

Most centrifugal fan impellers have shrouded blades as part of a fan wheel. The shrouds include annular plates that are fitted at each end of the blades, giving mechanical strength to the fan impeller and reducing leakage between blades and casing. Fluid leakage around fan impeller blades and between blades and fan casings substantially reduce fan efficiency, requiring more power for a given total fan pressure or volume flow.

Cross-flow, or tangential, fans have impellers with blades shaped like forward-curved centrifugal fan impellers. However, both ends of the impeller in a cross-flow fan are sealed and it is fitted into a casing in which fluid enters at the periphery on one side, passes through the impeller, and leaves from the periphery at the other side. The axes of the inlet and outlet are roughly perpendicular; therefore, the flow through a cross-flow fan is curved rather than diametral. Cross-flow fan blades are generally of rectangular shape and considerable length, disposed in a parallel longitudinal orientation, forming a cylindrical impeller comprised of blades that allow for the curved fluid flow path through the impeller unit.

Propeller fans are comprised of a motor driven sheet metal impeller, positioned in an orifice with relatively large clearance. Fluid flow through a propeller fan is analogous to flow through an orifice rather than strict linear/axial flow. Propeller fans and axial flow fans are generally analogous in terms of structure and the fluid mechanics of operation, and are equivalent for most applications.

Axial flow fans are those where the flow of the fluid is substantially parallel to the axis of the impeller hub. Axial flow fans can be placed in three primary categories: (1) fluid circulator, or free fan; (2) diaphragm-mounted fan; or (3) ducted fan. A free fan is one that rotates in a common unrestricted fluid space, for example, desk, wall, pedestal, and ceiling fans. Diaphragm-mounted fans transfer fluid from one relatively large space to another, as for example an exhaust or ventilation fan that drives fluid from a factory or warehouse to the external atmosphere, or alternatively, drives outside fluid into an open internal area or transfers fluid between inside areas. Diaphragm-mounted fans do not use ductwork or fine-clearance cylindrical casings. Ducted fans constrain fluid flow in an axial direction with an enclosing shroud or duct. The minimum duct length required to satisfy the ducted condition must be in excess of the axial distance between inlet to, and outlet from, the impeller blades.

Generally, fluid approaches the fan impeller on the low pressure inlet side in an axial direction and leaves from the high pressure outlet side with an axial and rotational component due to work done by the impeller torque. Since the purpose of a fan is to move fluids against ambient pressures, the rotational velocity component is disadvantageous because it reduces the available total pressure generated by a fan to produce volume flow in an axial direction.

Notwithstanding the numerous fan designs developed to maximize fan efficiency while minimizing noise, vibration, and cost, a number of problems still exist in fan design for which adequate solutions have yet to be developed. For example, like centrifugal fans, axial flow and propeller-type fans suffer from fluid leakage around the fan impeller blade tips, and between blade tips and fan casings, which substantially reduces fan efficiency, requiring higher rotational impeller speeds and more power to produce a given total fan pressure or volume flow. This problem is characterized in that the fluid passing through the fan reverses direction at the blade tips, flows around the blade tips from the outlet surface to the inlet surface in a countercurrent fashion, and lowers efficiency as fluid discharged from the high pressure side bleeds back to the low pressure side creating vortices, stall conditions, and other turbulent flow characteristics, and further increasing undesirable noise and vibration.

An additional problem with conventional fan blades, for example, circular arc, flat undersurface, elliptical, and planar blades, is the rotational velocity component imparted to the fluid due to the torque of the fan blades. This component can decrease fan efficiency by decreasing the amount of available total static pressure on the discharge side, and as a result, decreasing the total volume flow for a given impeller speed and configuration. While conventional methods exist to reduce this problem, for example, upstream or downstream guide vanes and contra-rotating assemblies, these methods possess attendant problems of their own, including, for example, increased noise and power requirements.

Moreover, conventional fan blades are not capable of redirecting the rotational velocity component to create a radial component, which in effect would push residual fluid flow (i.e. fluid flow that is not in an axial direction) in a radial direction and would form a more collimated and laminar volume flow from the fan unit.

An additional problem with conventional fan blades in axial flow and propeller-type fan systems is the clearance space on the low pressure suction/inlet side required to achieve acceptable operating performance. In particular, axial flow and propeller-type fans need sufficient clearance between the low pressure side of the blades and an adjacent surface, for example a solid and continuous wall or ceiling, in order to achieve efficient flow-through performance. If an impeller assembly is located too closely adjacent to a solid and continuous surface, turbulent flow characteristics such as stalls and vortices develop on the suction surface of the impeller blades. This poses a problem in areas of limited space, for example, in rooms with low ceilings or limited floor space, where it would be advantageous to achieve maximal fluid flow while minimizing the dead space behind the low pressure suction side of any fan units.

Accordingly, it would be desirable to provide a fan blade configuration that increases fan efficiency (increased total static fan pressure and volume flow at lower impeller speeds and lower power requirements), decreases noise and vibration, and creates a more focused and collimated volume flow.

BRIEF SUMMARY OF THE INVENTION

The present invention is generally directed toward improved fan blades which reduce, minimize, or eliminate countercurrent fluid bleeding, blade tip vortices, stalling effects, turbulent flow conditions, low pressure suction/inlet side clearance space, noise, vibration, and the rotational fluid velocity component, and further which increase the radial fluid velocity component and overall fan efficiency. Fluid-directing blade structures (described hereinafter as “baffles” or “baffle elements”) are disposed at the distal end (i.e., the tip end) of the fan blades provided herein. The baffle elements are positioned on the distal end of each fan blade, directed toward the low pressure suction/inlet side, the high pressure discharge/outlet side, or both, and further at a first specified angle with respect to the radial axis of the fan blade, a second specified angle with respect to the low pressure surface of the fan blade, and/or at a third specified angle with respect to the high pressure surface of the fan blade.

In one embodiment, the present invention is directed toward fan blades including a blade body having a leading edge, a trailing edge, a proximal end, a distal end, a high pressure surface, a low pressure surface, and a radial axis, and a baffle element, such that the baffle element is positioned on the distal end of the blade body at a first angle with respect to the radial axis, at a second angle with respect to the low pressure surface, and/or at a third angle with respect to the high pressure surface.

In another embodiment, the present invention is directed toward fan blades including a blade body having a leading edge, a trailing edge, a proximal end, a distal end, a high pressure surface, a low pressure surface, and a radial axis, and a baffle element, such that the baffle element is positioned on the distal end of the blade body and extending from the low pressure surface at an angle of approximately 45-degrees with respect to the radial axis, and at an angle of approximately 90-degrees with respect to the low pressure surface.

In yet another embodiment, the present invention is directed toward axial-flow fans including a drive mechanism, a hub rotatably coupled to the drive mechanism, a plurality of fan blades, and a baffle element attached to at least one of the high pressure surface, the low pressure surface, or both of at least one blade of the plurality of blades at the distal end of the blade, such that the blades are attached to the hub at the proximal ends, and positioned such that the distal ends project in a substantially radial direction away from the hub, and such that the baffle element is positioned on the distal end at a first angle with respect to the radial axis, at a second angle with respect to the low pressure surface, and/or at a third angle with respect to the high pressure surface of the blade.

Other features and advantages will be apparent from the following description, including the drawings, and from the claims set forth.

BRIEF DESCRIPTION OF THE DRAWINGS

The various described embodiments will hereinafter be described in conjunction with the appended drawings provided to illustrate and not limit the described embodiments, wherein like designations denote like elements, and in which:

FIG. 1 is a side view parallel to the plane of rotation of a conventional propeller or axial flow type fan illustrating fluid flow currents when operating in forward rotation;

FIG. 2 is a bottom or front view, orientation depending, of a conventional propeller or axial flow type fan illustrating peripheral tip vortices;

FIG. 3 is a side view parallel to the plane of rotation of a fan with baffle elements according to non-limiting embodiments of the present invention illustrating fluid flow currents when operating in forward rotation;

FIG. 4 is a bottom or front view, orientation depending, of a fan with baffle elements according to non-limiting embodiments of the present invention;

FIG. 5 is a side view parallel to the plane of rotation of a conventional propeller or axial flow type fan illustrating fluid flow currents when operating in reverse rotation;

FIG. 6 is a side view parallel to the plane of rotation of a fan with baffle elements according to non-limiting embodiments of the present invention when operating in reverse rotation;

FIG. 7 is view perpendicular to the plane of rotation of a fan blade according to non-limiting embodiments of the present invention;

FIG. 8 is a view perpendicular to the plane of rotation of an assembly of fan blades according to non-limiting embodiments of the present invention;

FIG. 9A is a side view parallel to the plane of rotation of an assembly of fan blades according to non-limiting embodiments of the present invention,FIG. 9B is a view perpendicular to the plane of rotation of the assembly depicted inFIG. 9A;

FIG. 10 is a side view parallel to the plane of rotation of a fan blade according to non-limiting embodiments of the present invention;

FIG. 11A is a partial view parallel to the plane of rotation of a baffle element according to non-limiting embodiments of the present invention,FIG. 11B is a partial view to the plane of rotation of a baffle element according to non-limiting embodiments of the present invention;

FIG. 12 is a view parallel to the plane of rotation of a baffle element according to non-limiting embodiments of the present invention;

FIGS. 13A,13B, and13C are views parallel to the plane of rotation of assemblies of fan blades according to non-limiting embodiments of the present invention;

FIG. 14A andFIG. 14B are views perpendicular to the plane of rotation of fan blades according to non-limiting embodiments of the present invention;

FIG. 15 is a view parallel to the plane of rotation of a baffle element according to non-limiting embodiments of the present invention;

FIG. 16A is a view parallel to the plane of rotation of a fan blade according to non-limiting embodiments of the present invention.FIG. 16B is a view perpendicular to the plane of rotation of the fan blade depicted inFIG. 16A;

FIG. 17A is a view parallel to the plane of rotation of a fan blade according to non-limiting embodiments of the present invention.FIG. 17B is a view perpendicular to the plane of rotation of the fan blade depicted inFIG. 17A;

FIG. 18 is a view perpendicular to the plane of rotation of a fan blade according to non-limiting embodiments of the present invention;

FIG. 19 is a view perpendicular to the plane of rotation of a fan blade according to non-limiting embodiments of the present invention;

FIG. 20 is a view perpendicular to the plane of rotation of a fan blade according to non-limiting embodiments of the present invention;

FIG. 21 is a view perpendicular to the plane of rotation of a fan blade according to non-limiting embodiments of the present invention;

FIG. 22 is a view perpendicular to the plane of rotation of a fan blade according to non-limiting embodiments of the present invention;

FIG. 23 is a view perpendicular to the plane of rotation of a fan blade according to non-limiting embodiments of the present invention;

FIG. 24 is a view perpendicular to the plane of rotation of a fan blade according to non-limiting embodiments of the present invention; and

FIG. 25 is a side view of an axial-flow fan according to non-limiting embodiments of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The described embodiments provide improved fan blades for reducing, minimizing, or eliminating countercurrent fluid bleeding, blade tip vortices, stalling effects, turbulent flow conditions, low pressure inlet/suction side clearance space, noise, vibration, and the rotational fluid velocity component, and further for increasing the radial fluid velocity component and overall fan efficiency.

Before various embodiments are explained in detail, it is to be understood that the described embodiments are not limited in application to the construction and arrangement of the structures, components, steps, and/or examples set forth in the following description or illustrated in the drawings. The described embodiments are capable of other forms and may be carried out in various ways. Also, it is understood that the phraseology and terminology used herein is for purpose of description and should not be regarded as limiting.

As used herein, the term “forward rotation” is intended to indicate the direction of rotation of a fan impeller such that the discharge surface corresponds to the forward-facing side of the impeller. For example, in a ceiling fan application, the orientation of the pitch of the blades is such that forward rotation would produce fluid flow down into the space below the fan, while alternatively, reverse rotation would produce fluid flow up through the fan impeller and into the space above the fan. There is no convention in the art defining forward or reverse rotation as either clockwise or counterclockwise rotation. Designers of fans determine what direction of rotation is forward rotation by setting the orientation of the blade pitch on a fan impeller and setting which side of the impeller is the forward-facing side. The fan blades disclosed herein are capable of application regardless of the respective directions of rotation. However, for purposes of illustration, and not to be regarded as limiting, forward rotation corresponds to clockwise rotation and reverse rotation corresponds to counterclockwise rotation of the fan impellers illustrated inFIGS. 2,4,7,8,9B,14A,14B,16B,17B,18,19,20,21, and22, which are front views of the forward-facing sides of the illustrated fan blades and fan impellers.

FIG. 1 illustrates a conventionalfan blade assembly10 in forward rotation, and the fluid flow currents associated therewith. During operation, the forwardly-rotatingblades20 generate lower pressure on the inlet/suction surface22 and higher pressure on the outlet/discharge surface23. Thelow pressure surface22 induces influx of fluid into therotating blades20, while thehigh pressure surface23 forces volume flow25 from the blades. Due to the pressure gradient across therotating blades20, a portion of the volume flow from thehigh pressure surface23 bleeds back, around the tips of the fan blades, to thelow pressure surface22, producingvortex currents24.

Thevortices24 produced by therotating blades20 reduce the total static pressure generated by the fan, and therefore reduce thevolume flow25 for given operating conditions (i.e., given power input and blade rotational speed). Thevortices24 produced by therotating blades20 further disrupt the volume flow in the annular region formed by the circular path of the tip portion ofblades20, as illustrated inFIG. 2 rotating in the direction indicated byarrow60. The disrupted fluid region includesvortices24, which can induce the formation of stall conditions (not shown), which are large secondary rotational fluid flows along the length of thelow pressure surface22 of thefan blade20. These turbulent fluid flow characteristics substantially reduce the efficiency of conventional fan blades.

As illustrated inFIG. 3, thebaffle elements150 according to various embodiments of the present invention increase fan blade efficiency by redirecting the fluid in the tip region ofrotating blades100. The redirection of the fluid by thebaffle elements150 locally increases the pressure on thelow pressure surface122 at thedistal tip region58 of thefan blade100, thereby locally reducing the pressure gradient across the fan blade at thedistal tip region58 relative to the pressure gradient across thefan blade100 proximally from thedistal tip region58.Baffle element150 further provides a barrier to prevent the formation of vortices around the blade tip. As illustrated inFIG. 4, this reduces the fluid turbulence in theannular region59 formed by the path of the tip portion ofrotating blades100. The reduction of vortices and other turbulent effects decreases the prevalence of stall conditions on thelow pressure surface122 of therotating blades100.

Thebaffle element150 additionally shunts fluid in the direction indicated byarrow57 inFIG. 4. The shunt imparts a radial velocity component to the fluid adjacent to the side of the rotating fan blades on whichbaffle element150 is positioned. When thebaffles150 are positioned on thelow pressure surface122 of the fan blade, the radial velocity component directs fluid radially inward to the low pressure side of the rotating blade assembly, where it is worked upon by theblades100 and discharged from the highpressure outlet surface123. In this mode, thefan blade100 withbaffle element150 has two propulsion areas: the highpressure outlet surface123 and the surface of thebaffle element150. The radial shunt of the fluid due to the propulsion area ofbaffle element150 partially offsets the efficiency losses due to the rotational component of the fluid discharged from the highpressure outlet surface123 due to the torque of rotatingfan blades100. The combined vortex shearing and fluid-shunting due to thebaffle elements150 results in a more focused and collimatedvolume flow125. Accordingly, thebaffle elements150 increase the available static fan pressure and volume flow for given operating conditions, and function as flow directing elements.

By way of example, and not intended as limiting, in fan applications where the fan can be operated in forward and reverse, the vortices that are produced by conventional fan blades are a substantial problem regardless of the direction of blade rotation. Various embodiments of the present invention provide baffle elements that function to increase fan efficiency and performance during operation in both forward and reverse directions.

FIG. 5 illustrates a conventionalfan blade assembly10 in reverse rotation, and the fluid flow currents associated therewith. During operation, the reversely-rotatingblades20 generate lower pressure on the bottom-facing surface and higher pressure on the top-facing surface. Thelow pressure surface22 induces influx offluid30 from below into therotating blades20, while thehigh pressure surface23 discharges volume flow from theblades20. A portion of the volume flow from thehigh pressure surface23 bleeds back, around the tips of the fan blades, to thelow pressure surface22 producingvortex currents24 due to the pressure gradient across therotating blades20.

As illustrated inFIG. 6, thebaffle elements150 redirect the fluid in thedistal tip region58 reducing, minimizing, or eliminating the vortices and flow disruptions in the periphery of the impeller area as in the case with forward rotation. However, in reverse rotation, the baffle elements shunt fluid in an outward radial direction. In this mode, thebaffle elements150 redirect at least a portion of the velocity component in the discharge flow fromhigh pressure surface123 into an outwardlyradial component134.

The effect of thebaffle elements150, as illustrated inFIGS. 3 and 6 respectively, is that in forward rotation, thebaffle elements150 are positioned on thelow pressure surface122 and produce a more densely focused and collimateddischarge volume flow125 approximately perpendicular to the plane of the fan impeller, whereas in reverse rotation, thebaffle elements150 are positioned on thehigh pressure surface123 and produce a more radially-distributeddischarge volume flow134 approximately parallel to the plane of the fan impeller.

FIG. 7 is a view perpendicular to the plane of rotation of afan blade100 according to non-limiting embodiments of the present invention. Theblade100 rotates in forward rotation in the direction indicated byarrow60 and the view is ofhigh pressure surface123.Blade100 is attached tohub160 at theproximal end140 of the blade.Blade100 is comprised of blade body includingdistal end130, leadingedge10, trailingedge120, and radial axis A. Radial axis A designates a reference line originating at the center point ofhub160 and projecting in a radial direction, indicated as direction B inFIG. 7, through the body ofblade100. Positioned on thedistal end130 ofblade100 isbaffle element150.Baffle element150 is positioned such that it forms anangle170, indicated as θ, with respect to radial axis A ofblade100.

FIG. 8 is a view perpendicular to the plane of rotation of anassembly105 of fan blades according to non-limiting embodiments of the present invention. Thefan blades100 rotate in forward rotation in the direction indicated byarrow60. Eachblade100 is attached tohub160 at theproximal end140 of the blade. Each blade is further comprised ofdistal end130, leadingedge110, trailingedge120, radial axis A, and baffleelements150 positioned on the distal ends130 of theblades100 formingangle170 with respect to radial axis A. In this embodiment, leadingedge110, tailingedge120 and radial axis A are substantially parallel. The blade andhub assembly105 ofFIG. 8 depicts four baffled fan blades attached tohub160. It is understood that fan assemblies according to non-limiting embodiments of the present invention are not limited to any number of fan blades or baffled fan blades, and could include any number of baffled fan blades as part of an impeller or fan blade assembly suitable for the particular purposes and operating conditions of the fan.

FIG. 9A is a side view parallel to the plane of rotation of an assembly of fan blades according to non-limiting embodiments of the present invention.FIG. 9B is a view perpendicular to the plane of rotation of the assembly depicted inFIG. 9A. Thebaffle elements150 are attached to fanblades100 at their distal ends. Thefan blades100 are attached tohub160 at their proximal ends. Leadingedge110 and trailingedge120 are indicated in bothFIGS. 9A and 9B.

FIG. 10 is a side view parallel to the plane of rotation and along the length of afan blade100 according to non-limiting embodiments of the present invention. Thebaffle element150 is positioned on the distal end of theblade100 extending from thelow pressure surface122.Baffle element150 is positioned such that it forms anangle200, indicated as φ, with respect to thelow pressure surface122.

Thebaffle element150 is depicted extending from thelow pressure surface122 inFIGS. 10,11A,13A, and15. However, the positioning of thebaffle element150 is not limited to extension from thelow pressure surface122 of the fan blade, and can be positioned to extend from thehigh pressure surface123, as depicted inFIG. 11B, or from both thelow pressure surface122 and thehigh pressure surface123, as depicted inFIG. 12. In embodiments wherebaffle element150 is positioned such that it extends from both thelow pressure surface122 and thehigh pressure surface123, the baffle element forms athird angle250, indicated as λ inFIG. 12, with respect to thehigh pressure surface123.

As used herein, the term “approximately” to describe angle values in degrees is interpreted to encompass the stated value ±10-degrees. Also, it should be understood that any numerical range recited herein is intended to include all sub-ranges subsumed therein. For example, a range of “1 to 10” is intended to include all sub-ranges between (and including) the recited minimum value of 1 and the recited maximum value of 10, that is, having a minimum value equal to or greater than 1 and a maximum value of equal to or less than 10.

Thefirst angle170 formed between thebaffle element150 and the radial axis A of the fan blade can range from approximately 0-degrees to approximately 180-degrees, preferably from approximately 30-degrees to approximately 60-degrees, and most preferably is approximately 45-degrees.

FIGS. 13A,13B, and13C depict fan blade assemblies where thebaffle elements150 respectively extend from thelow pressure surface122, thehigh pressure surface123, and both thelow pressure surface122 and thehigh pressure surface123.

Baffle element

150 can be integrally formed as part offan blade100 as depicted inFIGS. 7 through 15. An integrally formed fan blade (i.e., a monolithic structure including the body of the blade and the baffle element), according to certain embodiments of the present invention, can be fabricated from any one of the numerous common solid component manufacturing methods well known to those of ordinary skill in the art, including, but not limited to, die casting, injection molding, sheet stamping, extrusion molding, and CNC machining. In addition to the baffle being integrally formed with the fan blade into a monolithic component, thebaffle element150 can be fabricated as aseparate component300, which is structured and configured to be fastened or attached, either permanently or removably, from the correspondingly structured and configuredfan blade375, as depicted inFIGS. 16A and 16B. Thebaffle element component300 can be attached to thefan blade375 atjunction350 by any means known to one of ordinary skill in the art, including, but not limited to, compression mechanisms, rivets, bolts, screws, other fasteners, adhesives, epoxies, and welds.

Baffle element

150 can further be manufactured as an appliance, attachment, or add-oncomponent400, which can be attached, permanently or removably, to aconventional fan blade475. In this manner, a baffle element can be applied to a conventional fan blade as a retrofit. As illustrated inFIGS. 17A and 17B, thebaffle appliance400 is structured and configured to mate with and attach toconventional fan blade475 atjunction450. Theappliance400 can be used to convert conventional fans into more efficient fans by utilizing the baffle element according to various embodiments of the present invention.

The baffle elements have been illustrated in the drawings and described herein as planar rectangular fin orwinglet type structures150. It is to be understood, however, that the baffle elements are not limited to rectangular or square shapes, but may be fabricated in any number of shapes including, but not limited to, rectangular, square, trapezoidal, rhomboidal, quadrilateral, triangular, elliptical, circular, semi-circular, pentagonal, hexagonal, heptagonal, and octagonal. Additionally, the baffle elements are not limited to planar structures, and may be fabricated in convex, concave, or other three-dimensional geometries. Moreover, thebaffle elements150 are not limited to the width of the fan blade, and may be structured and positioned such that they run shorter than (FIG. 18) or exceed (FIGS. 20 through 22) theleading edge110 and/or the trailingedge120 of any particular fan blade.

The baffle elements of the present invention have heretofore been described in conjunction with planar, rectilinear blades. However, the baffle elements of the present invention are applicable to any of the conventional types of fan blades, including, but not limited to, circular arc, flat undersurface, elliptical, and planar blades. The baffle elements are further applicable to propeller-type fan blades and any conventional axial-flow fan blade geometry. For example, and without limitation,FIGS. 18 through 21 depict a swept-blade configuration with abaffle element150 positioned on thedistal end130 at anangle170 with respect to radial axis A, and extending from the low pressure surface at a second angle of approximately 90-degrees. Dashedline180 inFIGS. 18 and 20 depicts the outline of the edge of a conventional swept fan blade. In various embodiments of the present invention, the portions of the blade withinline180 andbaffle element150 may be configured analogously to a conventional fan blade, wherein the blade terminates at the distal end. In such embodiments,baffle element150 extends from the low pressure surface, the high pressure surface, or both, intersecting the conventional swept blade proximal to the distal end. An embodiment where the baffle element intersects a rectilinear fan blade proximal to the distal edge is illustrated inFIG. 22.

In various embodiments of the present invention, the portions of the blade withinline180 andbaffle element150 are eliminated. In such embodiments, the fan blades terminate at the baffle element, which is directly positioned on the distal end as illustrated inFIGS. 19 and 21.

The fan blades have been illustrated and described herein as including at least one baffle element, wherein the baffle element is positioned on the distal end of the fan blade or is positioned at an intermediate location proximally with respect to the distal end. In various embodiments, the fan blades may include a plurality of baffle elements. For example,FIG. 23 illustrates a fan blade according to embodiments of the present invention wherein two

baffle elements

150 and151 are positioned on the blade body. The two

baffle elements

150 and151 are positioned on the blade body at

first angles

170 and171, respectively, with respect to radial axis A. The

angles

170 and171 may be of the same value or of different values. The

baffle elements

150 and151 may be of the same shape, size and configuration or of different shapes, sizes and configurations. The second angles (not shown) between the

baffle elements

150 and151 and the low pressure surface may be of the same value or of different values for each respective baffle element positioned on the blade body.

FIG. 23 depictsbaffle element150 positioned on thedistal end130 of the blade body andbaffle element151 positioned proximal from the distal end. Fan blades according to various embodiments are not limited to this configuration. For example,FIG. 24 depicts

baffle elements

150 and151, where both baffle elements are positioned proximal from thedistal end130.

The fan blades according to various embodiments of the present invention are not limited to any particular number of baffle elements, and can include any number of baffle elements suitable for the particular application of the fan blades. Moreover, regardless of the number of baffle elements per blade and their positioning on the blade body, the baffle elements may be manufactured as an appliance, attachment, or add-on component, which can be attached, permanently or removably, to a conventional fan blade. In this manner, baffle elements can be applied to a conventional fan blade as retrofits.

The baffle elements of the present invention can be incorporated into new fan designs, used as modifications to existing fan designs, or applied as retrofits of existing conventional propeller and/or axial-flow fans. The baffle elements are particularly suited for, but not limited to, use in axial-flow or propeller type fan units such as fluid circulator fans, free fans, diaphragm-mounted fans, propeller fans, and ducted fans.

Fan blades according to various embodiments of the present invention are applicable to common fan units including, but not limited to desk fans, wall fans, floor fans, window fans, pedestal fans, ceiling fans, box fans, ventilation fans, and industrial fans. For example, in ceiling fan applications, as illustrated inFIG. 3, baffleelements150 reduce the amount of open space necessary between the ceiling and therotating blades100 in order to achieve optimal fluid volume flow-through125, maximizing convectional cooling.Baffle elements150 are also advantageous when a ceiling fan is operated in reverse rotation, as illustrated inFIG. 6, wherebaffle elements150 produce aradial shunt134 that efficiently distributes fluid throughout a room, rather than creating localized turbulent effects, for example vortices34 inFIG. 5, common to conventional fan blades. This reduction in low pressure side space is particularly advantageous for rooms with low ceilings, where a conventional ceiling fan would be impractical.

An additional example of a non-limiting embodiment of the present invention would be a large-scale industrial or mobile box fan positioned with a vertical plane of rotation. Such fans conventionally require significant free space on the low pressure suction/inlet side in order to achieve optimal volume flow. The baffle elements according to non-limiting embodiments of the present invention allow such fans to develop optimal volume flow with reduced low pressure side free space at moderate rotational speeds, whereas conventional fans would require substantially higher fan speeds and increased power consumption to achieve comparable flow.

Anexemplary fan unit500 according to various embodiments of the present invention is illustrated inFIG. 23.Fan unit500 includes adrive mechanism510, for example a direct current (DC) or a pulse width modulated (PWM) motor; ahub160 rotatably coupled to thedrive mechanism510; and a plurality offan blades100, at least one of which includes abaffle element150. The methods in which the components are fabricated and assembled, and the incorporation of additional components into the unit, for example control means, support structures, and casings or housings, are the subject of design or engineering choice, the exercise of which does not take the fan unit outside the scope of the present invention.

Advantages of embodiments of the present invention additionally include noise reduction, because turbulent flow conditions that create noise are reduced, minimized, or eliminated; and the aerodynamic efficiency of the fan blades are increased because the baffle elements provide for radial fluid direction and shunting toward the low pressure inlet, providing for increased fluid volume flow and increased static total pressure for the same fan speed, size, and power requirements.

While the present invention has been described in terms of fans and fan blades, which traditionally operate in air environments, it is to be understood that the baffle elements according to various embodiments are applicable to other fluid handling equipment and fluid systems including, but not limited to, compressors and gas turbines, and liquid handling systems, for example propeller-type water conveying equipment.

It is to be understood that the figures and descriptions of the present invention have been simplified to illustrate elements that are relevant for a clear understanding of the present invention, while eliminating, for purposes of clarity, other elements, such as, for example, details regarding specific hardware components generally associated with fan equipment. Those of ordinary skill in the art will recognize that the specific fan equipment of interest will dictate the type, configuration, and positioning of the fan unit and dimensioning of components. However, because the technical details and functionality of such elements are well known in the art and because they do not facilitate a better understanding of the present invention, a detailed discussion of such elements is not provided herein.

While several embodiments of the invention have been described, it should be apparent, however, that various modifications, alterations and adaptations to those embodiments may occur to persons skilled in the art with the attainment of some or all of the advantages of the disclosed invention. Therefore, this application is intended to cover all such modifications, alterations and adaptations without departing from the scope and spirit of the disclosed invention as defined by the appended claims.

Claims

1. A fan blade comprising:

a blade body including a leading edge, a trailing edge, a proximal end, a distal end, a high pressure surface, a low pressure surface, and a radial axis; and

at least one baffle element positioned on the blade body at a first angle with respect to the radial axis and at a second angle with respect to the low pressure surface.

2. The fan blade ofclaim 1, further comprising a plurality of baffle elements positioned on the blade body at a first angle with respect to the radial axis and at a second angle with respect to the low pressure surface.

3. The fan blade ofclaim 1, wherein the at least one baffle element is positioned on the distal end.

4. The fan blade ofclaim 1, wherein the first angle with respect to the radial axis is in the range of approximately 30-degrees to approximately 60-degrees.

5. The fan blade ofclaim 1, wherein the first angle with respect to the radial axis is approximately 45-degrees.

6. The fan blade ofclaim 1, wherein the at least one baffle element extends from the low pressure surface.

7. The fan blade ofclaim 1, wherein the second angle with respect to the low pressure surface is approximately 90-degrees.

8. The fan blade ofclaim 1, wherein the at least one baffle element extends from both the low pressure surface and the high pressure surface.

9. The fan blade ofclaim 8, wherein the second angle with respect to the low pressure surface is approximately 90-degrees, and a third angle between the baffle element and the high pressure surface is approximately 90-degrees.

10. The fan blade ofclaim 1, wherein the at least one baffle element extends from the high pressure surface.

11. The fan blade ofclaim 1, wherein the second angle with respect to the low pressure surface is approximately 270-degrees.

12. The fan blade ofclaim 1, wherein the at least one baffle element is configured to be removably attached to the blade body.

13. The fan blade ofclaim 1, wherein the blade is utilized in an assembly comprising a plurality of fan blades.

14. A fan blade comprising:

at least one baffle element positioned on the distal end of the blade body at a first angle of approximately 45-degrees with respect to the radial axis and extending from the low pressure surface at a second angle of approximately 90-degrees with respect to the low pressure surface.

15. A fan blade comprising:

a plurality of baffle elements each positioned on the blade body at a first angle with respect to the radial axis and at a second angle with respect to the low pressure surface.

16. An fan comprising:

a hub;

a plurality of blades, each blade comprising a leading edge, a trailing edge, a proximal end, a distal end, a high pressure surface, a low pressure surface, and a radial axis, and each blade attached to the hub at the proximal end and positioned such that the distal end projects in a substantially radial direction away from the hub along the radial axis; and

a plurality of baffle elements attached to the plurality of blades and positioned at a first angle with respect to the radial axis and at a second angle with respect to the low pressure surface.

17. The fan ofclaim 16, wherein the baffle elements are positioned on the distal ends of the fan blades.

18. The fan ofclaim 16, wherein the baffle elements are attached to the low pressure surfaces of the blades.

19. The fan ofclaim 16, wherein the first angle with respect to the radial axis is approximately 45-degrees and the second angle with respect to the low pressure surface is approximately 90-degrees.

20. A baffle element configured to be retrofit to a fan blade, the fan blade comprising a leading edge, a trailing edge, a proximal end, a distal end, a high pressure surface, a low pressure surface, and a radial axis, wherein the baffle element is configured to be positioned on the fan blade at a first angle with respect to the radial axis and at a second angle with respect to the low pressure surface.