WO2018042381A1

WO2018042381A1 - A ceiling fan

Info

Publication number: WO2018042381A1
Application number: PCT/IB2017/055273
Authority: WO
Inventors: Hari. K. HARIKUMAR; G.g.k MURTHY; Amos WINTER; Jena CHITTARANJAN
Original assignee: Usha International Limited
Priority date: 2016-09-02
Filing date: 2017-09-01
Publication date: 2018-03-08
Also published as: CN109964042A

Abstract

The present disclosure provides a fan comprising a plurality of fan blades connected to a fan body. Each of the plurality of fan blades has an airfoil cross section, defined by a leading edge and a trail edge. Additionally, each of the plurality of fan blades are connectable to the fan body such that, a longitudinal axis of each of the plurality of blades is angularly displaced with respect to an imaginary radial line intersecting the fan body and the corresponding blade of the plurality of blades, defining a sweep angle. The sweep angle increases air flow in the downward direction and counters the problem of creation of negative suction pressure underneath the fan when in motion. Also, each of the plurality of blades are twisted and tilted at preferred angles, in order to minimize aerodynamic losses and increase volume of air striking surface of the plurality of fan blades.

Description

A CEILING FAN

TECHNICAL FIELD

Present disclosure generally relates to the field of home appliances. Particularly, but not exclusively, the present disclosure relates to fans. Further, embodiments of the disclosure disclose a ceiling fan with airfoil profiled blades.

BACKGROUND OF THE DISCLOSURE

In general, cooling devices are used to improve comfort levels of occupants within a given coverable area. The cooling devices circulate cool air within the confined spaces like rooms, cabins, halls, and the like. One such widely used cooling device or appliance is a fan. Conventionally, numerous types of fans including ceiling fan, table fan, pedestal fans have been developed and used to circulate air. Out of various types of fans, ceiling fans are most widely used owing to their inherent advantages. Typically, the ceiling fans are powered by electric motors enclosed within an enclosure, such as housing connected to a portion of fan body to which a plurality of blades are removably connected. The fan body, in general, may be suspended from the ceiling, to a desired distance. The power from the motor is transmitted to the fan body to rotate the fan. The plurality of blades are angularly spaced about the fan body such that the air mass which attacks the moving blades is driven (or deflected) downwards towards the floor.

Conventionally, the plurality of blades of a fan are manufactured so as to have various profiles including straight, faceted, curved, and so on. The plurality of blade profile constitutes one of the aspects which determines output and efficiency of a fan. Generally, the plurality of blades used for ceiling fan are manufactured from materials selected from variety of classes including metals, composites, wood, plastic, and so on. Further, the plurality of blades are manufactured by several manufacturing processes including but not limited to injection molding, sheet metal forming, cutting, etc, which involves reducing the raw material of near net shape into each of the plurality of blades with desired final shape and dimensions. However, the type of manufacturing process employed depends on nature of material selected, geometrical requirements and dimensions of the finished blade. For example, in case of manufacturing a blade with simple profile, such as a flat blade, an economical manufacturing process like simple forming and cutting operations can be employed. But there are few limitations associated with these planar flat blades which include noise generation, wobbling and poor aerodynamic characteristics, particularly with respect to deflection of incoming air in downward direction. Though the problem associated with deflection of incoming air downwards can be minimized by carrying out few modifications to the blade, such as tilting the blade with respect to horizontal plane, the problem of poor aerodynamic characteristics is not completely addressed. In other words, such a modification will affect other aerodynamic characteristics of the blade. Accordingly, to move a given volume of air towards the floor, the fan must operate at higher angular speeds, thereby resulting in consumption of more energy.

With the on-going efforts to improve the performance of ceiling fans, several solutions have been proposed to increase air circulation rate of commercially available ceiling fans which includes modifications to known fan blade profiles. These modifications include varying cross- sectional dimensions along length of blades, providing twist, manufacturing the blades in a longitudinal curvilinear configuration with substantial angles of up to 30 degrees throughout the cross section, and so on.

Further, with the research studies and experimental investigations, it is proven that in tropical countries like India, an output of 200 to 235 cubic metre per minute of air flow would be required for providing comfortable zone for the occupants. In the conventionally available ceiling fans, motors with capacities as high as 50 watts to about 75 watts are used to generate an output of 200 to 235 cubic meter per minute (cmm) of air. This results in consumption of electrical power at a relatively larger rate. In some of the other conventionally available fans, the comfort level of air flow can be achieved at less power consumption with the use of high end motors, such as brushless DC motors. However, use of such high-end motors increases overall cost of the fan.

In light of foregoing discussion, it is necessary to develop an improved ceiling fan to overcome one or more limitations stated above.

SUMMARY OF THE DISCLOSURE

One or more limitations of conventional ceiling fans are overcome and additional advantages are provided through the present disclosure. Additional features and advantages are realized through the techniques of the present disclosure. Other embodiments and aspects of the disclosure are described in detail herein and are considered a part of the claimed disclosure. In one non-limiting embodiment of the present disclosure, a fan is disclosed. The fan includes a fan body, which is disposable from a first plane to a second plane. Further, the fan body houses a motor, to drive the fan body. The fan further includes a plurality of fan blades, where each of the plurality of the fan blades is profiled with an airfoil cross-section. Additionally, each of the plurality of fan blades are connectable to the fan body such that, a longitudinal axis of each of the plurality of blades is angularly displaced with respect to an imaginary radial line intersecting the fan body and the corresponding blade of the plurality of blades, defining a sweep angle.

In an embodiment of the present disclosure, the airfoil cross-section of each of the plurality of blades is defined by a leading edge and a trail edge, having varying height as a function chordal length.

In an embodiment of the present disclosure, width of each of the plurality of blades is constant along substantial portion of the length of each of the plurality of blades.

In an embodiment of the present disclosure, the sweep angle ranges from about 1 degrees to about 12 degrees.

In an embodiment of the present disclosure, the fan comprises a plurality of brackets each for securing at least one blade of the plurality of blades to the fan body.

In an embodiment of the present disclosure, a root end of each of the plurality of blades is twisted at an angle with respect to the second plane, defining an angle of twist.

In an embodiment of the present disclosure, the angle of twist ranges from about 7 degrees to about 10 degrees.

In an embodiment of the present disclosure, a tip end of each of the plurality of blades is tilted with respect to the second plane, defining an angle of tilt.

In an embodiment of the present disclosure, the angle of tilt ranges from about 1 degrees to about 6 degrees.

In an embodiment of the present disclosure, each of the plurality of fan blades is connectable to the fan body such that, the longitudinal axis of each of the plurality of blades is angularly lifted with respect to the second plane, defining an angle of lift. In an embodiment of the present disclosure, the angle of lift ranges from about 5 degrees to about 6 degrees.

It is to be understood that the aspects and embodiments of the disclosure described above may be used in any combination with each other. Several of the aspects and embodiments may be combined together to form a further embodiment of the disclosure.

The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

The above-mentioned aspects, other features and advantages of the disclosure will be better understood and will become more apparent by referring to the exemplary embodiments of the disclosure, as illustrated in the accompanying drawings.

FIG. 1A illustrates perspective view of a ceiling fan, according to an exemplary embodiment of the present disclosure.

FIG. IB illustrates top view of the ceiling fan of FIG. 1A.

FIG. 2 illustrates top view of the ceiling fan of FIG. 1A with sections A-A, B-B, C-C, according to an embodiment of the present disclosure.

FIG. 3A illustrates front view of the ceiling fan along section A-A of FIG. 2.

FIG. 3B illustrates exaggerated view of Detail P shown in FIG. 3A.

FIG. 4A illustrates front view of the ceiling fan along section B-B of FIG. 2.

FIG. 4B illustrates exaggerated view of Detail Q shown in FIG. 4A.

FIG. 5 illustrates front view of the ceiling fan along section C-C of FIG. 2. FIG.6 illustrates perspective view of one of plurality of fan blades along with flow dynamics of air, according to an exemplary embodiment of the present disclosure.

The figures depict embodiments of the disclosure for purposes of illustration only. One skilled in the art will readily recognize from the following description that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles of the disclosure described herein.

DETAILED DESCRIPTION

While the embodiments in the disclosure are subject to various modifications and alternative forms, specific embodiment thereof has been shown by way of example in the figures and will be described below. It should be understood, however that it is not intended to limit the disclosure to the particular forms disclosed, but on the contrary, the disclosure is to cover all modifications, equivalents, and alternative falling within the scope of the disclosure.

The terms "comprises", "comprising", or any other variations thereof used in the disclosure, are intended to cover a non-exclusive inclusion, such that a device, assembly, mechanism, system, method that comprises a list of components does not include only those components but may include other components not expressly listed or inherent to such system, or assembly, or device. In other words, one or more elements in a system proceeded by "comprises... a" does not, without more constraints, preclude the existence of other elements or additional elements in the system or mechanism.

Embodiments of the present disclosure discloses a fan. The fan includes a fan body, where the fan body is disposable from a first plane to a second plane. Further, the fan body houses a motor, for driving purpose. The fan further includes plurality of fan blades, where each of the plurality of blades is profiled with an airfoil cross-section. Additionally, airfoil cross-section of each of the plurality of fan blades has a vertical height in Y-direction that varies as a function of chordal length along X- direction. In an embodiment, the curvature of the blade as observed from tip end varies such that the vertical distance in the direction of Y varies as a function of X. Further, each of the plurality of fan blade is angularly displaced, twisted and tilted with respect to the first plane and the second plane, to connect at a predetermined angular orientation. In addition, the angular orientation of the plurality of fan blades determines the angle at which the air strikes the blade surface, and is commonly known by the term "angle of attack" in aerodynamics. The term angle of attack in simple aerodynamic terms can be defined as an angle between apparent air flow direction towards the blade and the chordal plane of each of the plurality of fan blades. In one embodiment of the present disclosure, the angle of attack of each of the plurality of fan blades ranges between 6 degrees and 11 degrees.

Further, each of the plurality of fan blades is connected to the fan body, and is disposed at a sweep angle with respect to radial direction of the fan body. In an embodiment of the present disclosure, the sweep angle may be configured either in same direction as the rotation of the fan, or in opposite direction to direction of rotation of the fan. In one embodiment of the present disclosure, the sweep angle of each of the plurality of fan blades ranges between 1 degrees and 12 degrees. Furthermore, the plurality of fan blades may be twisted at an angle of twist, with respect to the first plane such that, a root end is inclined at an angle greater than inclination of a tip end of the plurality of fan blades with respect to the first plane. In one embodiment of the present disclosure, the root end of each of the plurality of fan blades is twisted at an angle ranging between 7 degrees and 10 degrees, and the tip end of each of the plurality of blades is inclined at an angle of tilt, ranging between 1 degrees and 6 degrees. Additionally, each of the blades also inscribes a lift angle where a longitudinal planar surface of the plurality of fan blades is inclined at an angle with respect to the horizontal plane. In one embodiment of the present disclosure, the lift angle of each of the plurality of fan blades ranges between 5 degrees and 6 degrees.

In an embodiment of the present disclosure, the motor, coupled to the fan body, drives the fan at a predetermined angular speed range. In one embodiment, the predetermined angular speed of the fan ranges from 200 revolutions per minute to 350 revolutions per minute. In an exemplary embodiment of the present disclosure, the capacity of the motor used to drive the fan ranges from 30 watts to 40 watts, and the fan is configured to generate an output of 210 cubic metre per minute to 240 cubic metre per minute of air circulation. In an embodiment, the efficacy of the fan, which is defined as ratio of output of the fan (in cmm) to power consumed, ranges from 6 to 7.

In an embodiment of the present disclosure, the airfoil blades are manufactured using materials selected from a group of metals and metallic alloys containing Aluminium or Steel as major component. The width of the blade so manufactured can be uniform across the entire length or most of the length, or can be non-uniform across the length. In an embodiment of the present disclosure, the width is uniform at 3.5 inches over most of the length of the blade. In an alternate embodiment, the width can taper between 5 inches at root end to 3 inches at tip end or vice versa. In an embodiment, the overall length of blades is selected such that sweep diameter of the fan is 1.2 metres.

Reference will now be made to a ceiling fan comprising airfoil shaped blades, and is explained with the help of figures. The figures are for the purpose of illustration only and should not be construed as limitations on the arrangement. In the foregoing description and the drawings, a ceiling fan is explained as an exemplary embodiment of the disclosure. One should not consider the same as limitation, and may extend the configurations of the fan to any other fan such as table fan, and wall hanging fan without deviating from scope of the present disclosure.

FIGS. 1A and IB are exemplary embodiments of the present disclosure which illustrate perspective view and top view of a ceiling fan (100) with a plurality of fan blades (104) connectable and/or assembled to a fan body (103). As explained earlier, the ceiling fan (100) may be suspended from a first plane (G-G), alternatively referred as ceiling plane, via a supporting member such as a hook which is fixed to such plane. The ceiling fan (100) is typically an assembly of several components or sub-assemblies. As it can be seen in FIG. 1A, the top most portion of the ceiling fan (100) is a cup like member (101) which conceals the connecting elements and the supporting member onto which the ceiling fan (100) is hung. The cup like member (101) also conceals electronic components and wires which are connected to the motor [not shown] . Further, a shaft or a rod like member projecting from the cup shaped member (101) supports the fan body (103) and is commonly known by term downrod (102). The downrod (102) ensures that the fan body (103) is distanced from the ceiling plane (G-G) and disposed on a second plane (H-H), which may also be known as a horizontal plane. The downrod (102) further carries a housing (105) which encloses the motor. The fan body (103) is coupled to a motor shaft or a motor spindle [not shown] such that, when power is switched ON, the fan body (103) rotates along with the motor shaft or motor spindle.

Now, reference is made to FIG. IB which illustrates top view of the ceiling fan (100) as observed from the ceiling plane (G-G). The fan body (103) is assembled with a plurality of fan blades (104) via a plurality of brackets (104A). The plurality of brackets (104 A) are either integrally manufactured with the fan body (103) or connected by temporary or permanent joints such as, but not limiting to, fasteners, welds, rivets, and the like. Similarly, the plurality of fan blades (104) are joined to the plurality of brackets (104A) by temporary joints such as, but not limiting to, rivets, screws, bolts, and the like. In an embodiment, when the fan body (103) rotates, a tip end (104B) of each of the plurality of fan blades (104) circumscribe a circle (R) with a predetermined diameter (φ), defined as sweep diameter (φ). Further, according to embodiments of the present disclosure, each of the plurality of fan blades (104) has an airfoil cross-section whose vertical height in Y-direction varies as a function of chordal length from leading edge (L) to a trailing edge (T) along longitudinal axis (X-X). In an embodiment, the curvature of the plurality of fan blades (104) as observed from the tip end (104B) varies such that, the vertical distance in the direction of Y varies as a function of X according to the exemplary values tabulated in Table 1 depicted below.

Table 1: Variation of vertical height in Y-direction as a function of chordal length along

X- direction

One should note that the values indicated in the above table are exemplary values, and should not be considered as limitation to the present disclosure. The values may be varied by a person skilled in the art without deviating from the scope of the present disclosure. FIG. 2 is an exemplary embodiment of the present disclosure which illustrates top view of the ceiling fan (100) of FIGS. 1A and IB with sections A-A, B-B and C-C. As shown in FIG. 2, the plurality of fan blades (104) of the ceiling fan (100) are assembled to the fan body (103) such that, each of the plurality of fan blades (104) is angularly displaced at an angle "Θ" with respect to an imaginary radial axis (R-R) connecting the fan body (103) and the corresponding blade of the plurality of fan blades (104). This indicates that the longitudinal axis (X-X) of the plurality of fan blades (104) is not normal to the fan body (103) but, is offset at an angle (Θ). The angle Θ is termed as sweep angle, and is provided either in same direction as the rotation of the fan, or in opposite direction to direction of rotation of the fan. Providing sweep angle may increase air flow in the downward direction and counters the problem of creation of negative suction pressure underneath the ceiling fan (100) when in motion. In one embodiment of the present disclosure, the sweep angle (Θ) of each of the plurality of fan blades ranges from about 1 degrees to about 12 degrees. It may be noted that the angle of sweep (Θ) may also be a function of number of fan blades (104) connectable to the fan body (103), dimension and structure of the fan body (103), and may vary accordingly.

FIGS. 3 A and 3B are exemplary embodiments of the present disclosure which illustrate sectional view of the ceiling fan (100) along the section A-A of FIG. 2 and exaggerated view of detail P of FIG. 3A respectively. Referring to FIG. 3B, the root end (104C) [shown in FIGS. IB and 2] of each of the plurality of fan blades (104) are twisted with respect to the horizontal plane (H-H) parallel to ceiling plane (G-G), to define an angle of twist which is designated by (a). In one embodiment of the present disclosure, the angle of twist (a) ranges from about 7 degrees to about 10 degrees. The angular of twist (a) of the root end (104C) may increase the extent or volume of air striking the surfaces of the plurality of fan blades (104), so that there is an improved deflection of incoming air in downward direction, which in turn results in improved air distribution for ambient cooling.

FIGS. 4A and 4B are exemplary embodiments of the present disclosure which illustrate sectional view of the ceiling fan (100) along the section B-B of FIG. 2 and magnified view of detail Q of FIG. 4A respectively. As it can be seen in FIG. 4B, the magnified view of detail Q shows inclination or tilt of the tip end (104B) [shown in FIGS.1 A and 2] of the plurality of fan blades (104) with respect to horizontal plane (H-H) and the ceiling plane (G-G), to define an angle of tilt designated by β. In one embodiment of the present disclosure, angle of tilt (β) ranges from about 0 degrees to about 6 degrees. The angle of tilt (β) of tip end (104B) increases the extent or volume of air striking the surfaces of the plurality of fan blades (104) so that, there is an improved deflection of incoming air in downward direction, which in turn results in improved air distribution for ambient cooling. In an embodiment of the present disclosure, the angle of twist (a) at the root end (104C) may be equal to the angle of twist (a) of the tip end (104B) such that, the angle of sweep (Θ) is uniform along length of the plurality of fan blades (104).

In another embodiment of the present disclosure, the angle of twist (a) of the root end (104C) is greater than the angle of tilt (β) of the tip end (104B) such that, the angle of sweep (Θ) may not be uniform along length of the plurality of fan blades (104). This unequal angle of twist (a) and the angle of tilt (β) of the tip end (104B) and the root end (104C) makes the plurality of fan blades (104) twisted, resulting in improved efficacy of the ceiling fan (100).

FIG. 5 is an exemplary embodiment of the present disclosure which illustrates sectional view of the ceiling fan (100) along the section C-C of FIG. 2. As shown in FIG. 5, the longitudinal axis of each the plurality of fan blades (104) is provisioned with an inclination or tilt with respect to the horizontal plane (H-H) parallel to ceiling plane (G-G), to define an angle of lift designated by (δ). In one embodiment of the present disclosure, the angle of lift (δ) ranges from about 5 degrees to about 6 degrees. The angle of lift (δ) of each of the plurality of fan blades (104), within this range optimizes the spread or distribution of incoming air striking each of the plurality of fan blades (104).

Further, in an embodiment, the plurality of fan blades (104) that are assembled to the fan body (103) may be manufactured using materials selected from a group of metals and metallic alloys containing Aluminium or Steel as major component. In an embodiment, aluminium laminates may be used to fabricate the plurality of fan blades (104) owing to its superior aerodynamic characteristics such as but not limited to high strength to weight ratio, ease of manufacturing by simple, cost effective processes such as sheet metal forming, and so on. In addition to the nature of material and aforementioned aerodynamic characteristics, the dimensions and geometrical considerations play a vital role in output and cooling efficacy of the ceiling fan (100). In an embodiment, the width of the plurality of fan blades (104) so manufactured is uniform across the entire length of each of the plurality of fan blades (104) or to a substantial portion of the length of the plurality of blades (104). If, the width is uniform across the length, then each of the plurality of fan blades (104) may have a rectangular shape, when viewed from the ceiling plane (G-G). If, the width is uniform across most of the length, then there may be a slight taper at one of its ends (root end (104C) or tip end (104B)) such that, each of the plurality of fan blades (104) may define a trapezoidal cross-section with a predefined tapered angle. If, the width continuously varies across the length, from the root end (104C) to the tip end (104B), the predefined tapered angle will be slightly higher.

In an exemplary embodiment of the present disclosure, the width of each of the plurality of fan blades (104) varies uniformly at less than 3.5 inches. In another embodiment, the width varies at 5 inches at one of the ends (the tip end (104B) or the root end (104C)) to 3 inches at the opposite end (the root end (104C) or the tip end (104B)) taperedly. The width of the plurality of fan blades (104) is a salient factor which decides drag characteristics and downward flow rate of incoming air. In an embodiment, the aforementioned range of the plurality of fan blades (104) width minimizes drag and maximises downward flow rate of incoming air, thereby resulting optimized ambient cooling characteristics. In an embodiment, the overall length of the plurality of fan blades (104) is selected such that sweep diameter (φ) of the ceiling fan (100) is 1.2 metres, which also contributes to optimum spreading or distribution of air in downward direction. The air flow characteristics across the plurality of fan blades (104) are depicted in FIG. 6.

The motor [not shown] coupled to the fan body (103) is configured to drive the ceiling fan (100) at a predetermined angular speed range. In one embodiment of the present disclosure, angular speed of the ceiling fan (100) ranges from about 200 revolutions per minute to about 350 revolutions per minute. In another embodiment of the present disclosure, the capacity of the motor which is used to drive the ceiling fan (100) ranges from about 30 watts to about 40 watts, providing an output of about 210 cubic metre per minute to about 240 cubic metre per minute of air circulation. In an embodiment, the efficacy of the fan, which is defined as ratio of output of the ceiling fan (100) (in cmm) to power consumed, ranges from about 6 to about 7.

In an exemplary embodiment of the present disclosure, experimental investigations are conducted on four different fans assembled with airfoil blades having various configurations. The blade parameters and the motor specifications of these designs are depicted in Table 2 shown below. As depicted in Table 2, in one of the fans, where width of the plurality of fan blades varies in a tapered manner from about 5 inches at wider end to about 3 inches at narrow end. In other fans, the width is uniform at about 3 inches for the entire length or substantial portion of the length. Each of the plurality of fan blades either has a twisted profile with equal/unequal at the root end and the tip end, or has an untwisted profile with constant angle of sweep, as depicted in the table. In case of untwisted blades, the angle of tilt is uniform at about 5 degrees with the sweep angle of about 10 degrees, or without any sweep angle.

Further, two different motors with identical stator and rotor dimensions are employed to rotate the above-mentioned fan designs. The capacity, angular speed and circulation rate (output) for each of the fan designs is depicted in Table 2. From the values indicated in Table 2, efficacy i.e. ratio of output of the fan to power consumed, can be calculated. As it is evident from the table, the efficacy of each fan design ranges from 6 to 7 as compared to conventional fan designs whose efficacies range from about 4 to 5.

Table 2: Specifications of different ceiling fans Advantage(s :

The present disclosure provides a ceiling fan with airfoil blades whose profile maximizes downward flow rate, minimizes drag and optimizes spread or distribution of air within the space in which the fan is installed.

The present disclosure provides a ceiling fan with airfoil shaped blades which uses low capacity motor. This reduces power consumption, which indicates savings in operating and maintaining costs.

The present disclosure provides a ceiling fan in which specific portions of blades are inclined with respect to horizontal plane and radial lines. These angular inclinations minimize aerodynamic losses and improve efficacy i.e. ratio of output of fan to power consumed.

Equivalents:

The embodiments herein and the various features and advantageous details thereof are explained with reference to the non-limiting embodiments in the description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.

The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein. Throughout this specification the word "comprise", or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.

The use of the expression "at least" or "at least one" suggests the use of one or more elements or ingredients or quantities, as the use may be in the embodiment of the disclosure to achieve one or more of the desired objects or results.

Any discussion of documents, acts, materials, devices, articles and the like that has been included in this specification is solely for the purpose of providing a context for the disclosure. It is not to be taken as an admission that any or all of these matters form a part of the prior art base or were common general knowledge in the field relevant to the disclosure as it existed anywhere before the priority date of this application.

The numerical values mentioned for the various physical parameters, dimensions or quantities are only approximations and it is envisaged that the values higher/lower than the numerical values assigned to the parameters, dimensions or quantities fall within the scope of the disclosure, unless there is a statement in the specification specific to the contrary.

While considerable emphasis has been placed herein on the particular features of this disclosure, it will be appreciated that various modifications can be made, and that many changes can be made in the preferred embodiments without departing from the principles of the disclosure. These and other modifications in the nature of the disclosure or the preferred embodiments will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the disclosure and not as a limitation.

TABLE OF REFERRAL NUMERALS

Referral Numerals Description

100 Fan

101 Cup shaped member

102 Downrod

103 Fan body 104 Blades

104A Bracket

104B Tip end of blade

104C Root end of blade

105 Housing

Φ Sweep diameter of ceiling fan

R Circumference of the ceiling fan

L Leading edge

T Trailing edge

X X Axis of fan blade

G-G First plane/ceiling plane

H-H Second plane/horizontal plane

A-A Section along root end of blade

B-B Section along tip end of blade

C-C Section along fan body a Root end inclination β Tip end inclination δ Lift angle

Claims

Claims:

1. A fan (100), comprising:

a fan body (103) disposable from a first plane (G-G) to a second plane (H-H), wherein the fan body (103) houses a motor; and

a plurality of fan blades (104), each of the plurality of fan blades (104) are profiled with an airfoil cross-section,

wherein, each of the plurality of fan blades (104) are connectable to the fan body (104) such that, a longitudinal axis (X-X) of each of the plurality of fan blades (104) is angularly displaced with respect to an imaginary radial line (R-R) intersecting the fan body (103) and the corresponding fan blade of the plurality of fan blades (104), defining a sweep angle (Θ).

2. The fan (100) as claimed in claim 1, wherein the airfoil cross-section of each of the plurality of fan blades (104) is defined by a leading edge (L) and a trail edge (T) having varying height as a function chordal length.

3. The fan (100) as claimed in claim 1 , wherein width of each of the plurality of fan blades (104) is constant along substantial portion of the length of each of the plurality of fan blades (104).

4. The fan (100) as claimed in claim 1, wherein the sweep angle (Θ) ranges from about 1 degrees to about 12 degrees.

5. The fan (100) as claimed in claim 1, comprises a plurality of brackets (104 A) each for securing at least one blade (104) of the plurality of fan blades (104) to the fan body (103).

6. The fan (100) as claimed in claim 1, wherein a root end (104C) of each of the plurality of fan blades (104) is twisted at an angle with respect to the second plane (H-H), defining an angle of twist (a).

7. The fan (100) as claimed in claim 6, wherein the angle of twist (a) ranges from about 7 degrees to about 10 degrees.

8. The fan (100) as claimed in claim 3, wherein a tip end (104B) of each of the plurality of blades (104) is tilted with respect to the second plane (H-H), defining an angle of tilt

(P)

9. The fan (100) as claimed in claim 8, wherein the angle of tilt (β) ranges from about 1 degrees to about 6 degrees.

10. The fan (100) as claimed in claim 1, wherein each of the plurality of fan blades (104) is connectable to the fan body (103) such that, the longitudinal axis (X-X) of each of the plurality of fan blades (104) is angularly lifted with respect to the second plane (H- H), defining an angle of lift (δ).

11. The fan (100) as claimed in claim 10, wherein the angle of lift (δ) ranges from about 5 degrees to about 6 degrees.