FORM 2
THE PATENTS ACT, 1970
(39 OF 1970)
AND
THE PATENT RULES, 2003
COMPLETE SPECIFICATION
(See section 10 and rule 13)
“CEILING FAN BLADE WITH SHARKFIN PROFILE”
We, Bajaj Electricals Limited, a Indian National, of 45/47, Veer Nariman Road, Fort Mumbai- 400001, India.
The following specification particularly describes the invention and the manner in which it is to be performed.

FIELD OF INVENTION
The present invention relates to the field of air circulation devices. In particular, the present invention relates to a featured blade of a ceiling fan.
BACKGROUND OF THE INVENTION
Ceiling fans are mostly used domestically in sub- tropical/tropical regions worldwide. A conventional ceiling fan comprises a rod mounted on the ceiling, a motor unit connected with the rod, and a plurality of metal blades connected with the motor unit. In ceiling fans, the electric energy is transformed into mechanical energy by the rotation of the motor shaft. This energy is then converted into kinetic energy of the airflow by interaction with the blades. Conventional metal blades are usually flat and oriented at an inclination for cutting the air thereby provides circulation of air downwardly.
It is known in the art that the blade weight, blade configuration and profile of the blade plays significant role in performance of the ceiling fan. Accordingly, by enhancing the profile of the blade, it is possible to increase the coefficient of performance (COP) of a ceiling fan which describes the fan efficiency.
Also, during operation of the fan, as air passes through an upper surface of the blade, due to the fast-moving air, layer separation occurs, which in turn creates turbulence immediately after the leading edge of the blade. Such turbulence causes vibrations in the blade and said vibrations may results in failure of the blade and significantly affects the efficiency of the fan, and produces unacceptable levels of noise.
While the prior art discloses ceiling fan plastic blade with curved shape which may enhance the air delivery and reduce the noise generated due to improved air cutting thereby provide a better solution with optimum electricity consumption, however, there is a limitation with respect to said blades as further improvement of air delivery and reduction of noise would not be possible without increase the length of the blades. Also, to cater the vibration, the thickness and width of blade is to be increased. Such increase in length and width of the blades may result in more weight and higher electricity consumption.

Therefore, there is need for a blade for a ceiling fan which can overcome one or more limitations stated above or any other limitations associated with the prior art.
SUMMARY OF THE INVENTION
In an aspect of the present invention, there is provided a blade for a ceiling fan, the blade comprising: (a) a body longitudinally extending between a motor end and a tip end of the blade , and comprising a leading edge , and a trailing edge ; and (b) a plurality of fins located on the body of the blade protruding from a top surface of the blade , situated proximal to the leading edge .
In an aspect of the present invention, said plurality of fins have a first section proximal to the leading edge , a middle section , and a third section distal to the leading edge , the first section , second section , and third section in smooth transition to each other.
In an aspect of the present invention, said fin longitudinally extends transverse to the length of the blade .
In an aspect of the present invention, the first section and third section of the fin has a tapered profile.
In an aspect of the present invention, fins of plurality of fins has length between 10-40 mm; and width between 1-5 mm.
In another aspect of the present invention any two adjacent fins may be equidistant from each other or varying distance from each other.
In yet another aspect of the present invention, the distance between any two adjacent fins decreases from the motor end towards the tip end.
In another aspect of the present invention, the body of the blade has an aerofoil profile defined by the leading edge , a middle section , and the trailing edge, and the maximum thickness of the aerofoil defined at the middle section , and minimum thickness is defined at the leading edge .

In another aspect of the present invention, the blade depth is between 3-6 mm increasing towards the tip end from the motor end .
In still another aspect of the present invention, the blade twist angle is between 9-12 degrees decreasing from the motor end towards the tip end .
In still another aspect of the present invention, the leading edge thickness is between 1-3 mm; and trailing edge thickness is between 3-5.5 mm.
In yet another aspect of the present invention, the blade lift angle is between 5-8 degrees.
In yet another aspect of the present invention, the blade length is between 635-650 mm.
In another aspect of the present invention, the blade comprises a joining portion for fixing the blade to a motor assembly, wherein the joining portion has a thickness between 7-11 mm.
In another aspect of the present invention, the joining portion comprises a plurality of ribs for strengthening the joining portion.
In an aspect of the present invention, the blade width is between 95-200 mm.
In another aspect of the present invention, the blade width at the tip end is between 95-105 mm, blade width at the motor end is between 110-120 mm, and blade width at the middle section is between 125-135 mm.
In yet another aspect of the present invention, the air delivery of a plurality of blade mounted on a ceiling fan is between 250-270 CMM at 320-350 RPM, and sweep size is 1200 mm.
In still another aspect of the present invention, there is provided a ceiling fan comprising a plurality of blades , said blade comprising: (a) a body longitudinally extending between a motor end and a tip end of the blade , and comprising a leading edge , and a trailing edge ; and (b) a plurality of fins located on the body of the blade protruding from a top surface of the blade , situated proximal to the leading edge .
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 detailed description is described with reference to the accompanying figures. In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The same numbers are used throughout the figures to reference like features and components. Some implementations of the system(s), in accordance with the present subject matter, are described by way of examples, and with reference to the accompanying figures.
Figure 1 depicts the perspective view of ceiling fan (200) comprising a plurality of blades (100), in accordance with an embodiment of the present invention.
Figure 2-3 depicts the top surface view of the blade (100) comprising a plurality of fins (140), in accordance with an embodiment of the present invention.
Figure 4 depicts the side view of the blade (100), in accordance with an embodiment of the present invention.
Figure 5 depicts the sectional side-profile view of the blade (100), in accordance with an embodiment of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
While this invention is susceptible of embodiments in many different forms, there is shown in the drawings and will herein be described in detail, a preferred embodiment of the invention with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the broad aspects of the invention to the embodiment illustrated.
Before describing in detail, the various embodiments of the present disclosure it may be observed that the novelty and inventive step are in accordance with a blade for a ceiling fan. It is to be noted that a person skilled in the art can be motivated from the present disclosure

and can perform various modifications. However, such modifications should be construed within the scope of the invention.
Accordingly, the drawings are showing only those specific details that are pertinent to understanding the embodiments of the present disclosure so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having benefit of the description herein.
The terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that an assembly, setup, system, device 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 device or setup. In other words, one or more elements in the system or apparatus or device proceeded by "comprises a" does not, without more constraints, preclude the existence of other elements or additional elements in the assembly or system or apparatus or device.
The present invention provides a blade for a ceiling fan, the blade comprising: (a) a body longitudinally extending between a motor end and a tip end of the blade. The body comprise a leading edge and a trailing edge. The blade also comprises a plurality of fins located on the body of the blade, protruding from the top surface of the blade. The plurality of fins are situated proximal to the leading edge of the blade.
A fin of the plurality of fins has a first section proximal to the leading edge of the blade, a second section, and a third section distal to the leading edge of the blade. The first section of the fin, the second section of the fin, and the third section of the fin are in smooth transition to each other. The fins longitudinally extend transverse to the length of the blade.
In another embodiment, the blade comprises at least 2 fins. In an embodiment, the blade comprises 2, 3, 4, 5, 6, 7, 8, 9, or 10 fins. In an embodiment, the fins are located equidistant from each other. In another embodiment, the fins are located at varying distance from each other.
In an embodiment, the first section of the fin has a tapered profile. In another embodiment, the third section of the fin has a tapered profile. In an embodiment, the width of the first

section of the fin is more than the width of the third section of the fin. In an embodiment, the width of the second section of the fin is more than the width of the first or third section of the fin. In an embodiment, the width of the second section of the fin is more than the width of the first and third section of the fin. In an embodiment, the width of the base of the first, second, or third section of the fin in any cross-section is more than the width at the top of the fin. In an embodiment, the fin has aerofoil profile.
The fin has length between 10-40 mm, and width between 1-5 mm. In an embodiment, the length of the fin is 30 mm. In an embodiment, the length of the fin is 35 mm. In another embodiment, the length of the fin is 25 mm. In another embodiment, the length of the fin is 20 mm. In an embodiment, the width of the fin is 4 mm.
The body of the blade has an aerofoil profile defined by a leading edge, a middle section, and a trailing edge. A maximum thickness of the body of the blade is defined at the middle section, while minimum thickness is defined at the leading edge.
The depth of the blade is between 3-6mm, increasing towards the tip end from the motor end. In an embodiment, the depth is 3mm, 4mm, 5mm, or 6mm. The twist angle of the blade is between 9-12 degrees, decreasing from the motor end towards the tip end of the blade. In an embodiment, the twist angle of the blade is 9, 10, 11, or 12 degrees. The thickness of the leading edge of the blade is between 1-3mm. In an embodiment, the thickness of the leading edge of the blade is 1, 2, or 3mm. The thickness of the trailing edge of the blade is between 3-5.5mm. In an embodiment, the thickness of the trailing edge is 3.5, 4, 4.5, 5, or 5.5mm. The lift angle of the blade is between 5-8 degrees. In an embodiment, the lift angle of the blade is 5, 6, 7, or 8 degrees. The blade length is between 635-650mm.
The blade further comprises a joining portion for fixing the blade to a motor assembly of a fan. The thickness of the joining portion is between 7-11mm. In an embodiment, the thickness of the joining portion is 7, 8, or 9mm. In an embodiment, the joining portion comprises a plurality of ribs for strengthening the joining portion.
The width of the blade is between 95-200mm.. In an embodiment, the width of the blade at the tip end is between 95-105mm. In an embodiment, the width of the blade at the motor end

is between 110-120mm. In an embodiment, the width of the blade at the middle section is 125-135mm.
The present invention also provides a ceiling fan comprising a plurality of blades as substantially described herein. In an embodiment, the ceiling fan comprises 3 blades. In an embodiment, the ceiling fan comprises 4 blades.
The subject matter is now described regarding the drawings, wherein like reference numerals are used to refer to like features/elements throughout. In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the present invention. It may be evident; however, that such matter can be practiced without these specific details. In other instances, well–known structures are shown in diagram form to facilitate describing the invention.
Fig. 1 depicts an exemplary blade (100) mounted on a ceiling fan (200) according to an exemplary embodiment of the present invention. The ceiling fan (200) comprises a plurality of blades (100), a canopy (210) covering the down rod (not shown) and a motor assembly (220). In the ceiling fan (200), there are provided 3 blades (100), which are adapted to be mounted on a hub of the motor assembly (220) with fastening means. In an exemplary depiction of the blade (100) of the present invention, Fig.2 depicts the upper surface of the blade (100) comprising 5 fins (140), each of which are located proximal to the leading edge (112) of the blade (100) and distal to the trailing edge (114) of the blade (100). The fins (140) may be located equidistant from each other or in varying distance from each other. Fig. 2 also shows the motor end (120) and tip end (130) of the blade (100). The motor end (120) comprises a joining portion (160) for fixing the blade (100) to the motor assembly, and the joining portion (160) comprises a plurality of ribs (180) for imparting strength to the joining portion (160).
As seen in Fig.2 and Fig. 3, the fins are located at varying distance from each other. Particularly, the distance between adjacent fins is less closed to the tip end (130) of the blade (100) than at the motor end (120) of the blade (100). As seen from Fig. 3, the length of the fins (140) var from 10-40 mm. Particularly, a first fin (140) closest to the tip end (130) of the

blade (100) has a length of 20 mm and width of 4mm. A second fid (140) adjacent to the first fin (140) has a length of 25 mm and width of 4 mm. The lateral distance between the first fin and the second fin is 50 mm. A third fin (140) adjacent to the second fin (140) has a length of 30 mm and width of 4 mm. The lateral distance between the second and the third fin is 70 mm. A fourth fin (140) adjacent to the third fin (140) has a length of 35 mm and width of 4 mm. The lateral distance between the fourth and the third fin is 90 mm. A fifth fin (140) adjacent to the fourth fin (140) has a length of 30 mm and width of 4 mm. The lateral distance between the fifth and the fourth fin is 140 mm. It is understood to a person skilled in the art that the number of fins, length of fins, width of fins, and distance between any two adjacent fins as described in Fig. 3 are not limiting features of the present invention, and can vary as per requirement considerations.
Fig. 4 shows the lift angle (180) of the blade (100) as measured from the motor end (110) towards the tip end (120) with respect to the horizontal plane defined as axis X. The lift angle helps in improving the spread of air velocity from the center of the ceiling fan (200) thereby ensuring high air delivery. Particularly, in Fig. 4, the lift angle is 5.5 degrees.
Fig. 5 read with Fig. 3 shows the twist angle of the blade (100) with respect to the vertical plane defined as axis Y. The twist angle decreases from the motor end (110) towards the tip end (120) of the blade (100) as can be seen from the different sections, i.e., C-C, D-D, E-E and F-F (see Fig. 3). Fig. 5 ((cross-section of the different sections from Fig. 3)) also shows the varying thickness of the blade (100) as defined along the aerofoil profile of the blade (100). The varying thickness (162) along with aerofoil profile (150) of the blade (100) reduces turbulence at the upper surface and reduces vibrations and noise. As the leading-edge thickness is minimum, the resistance to air cutting is minimal. Further, when the air cut through the profile of the aerofoil (150) of the blade (100), the air moves from the leading edge (112) towards trailing edge (114) of the blade (100) through a lower surface and the upper surface of the blade. The air which passed through the lower surface of the blade presses the air downwards. Further, as the profile of the aerofoil (150) of the blade (100) is such that leading edge (112) thickness is minimum and the middle section (154) thickness is maximum, the flow of air through the upper surface become laminar. As the laminar flow of

air is achieved at the upper surface of the blade, the requirement of increasing thickness never arises. In an embodiment of the present invention, the ratio of thickness among leading edge thickness, middle section thickness and trailing edge thickness is 0.5: 1: 0.62, respectively. As seen in Fig. 5a, in section C-C, the thickness of the leading edge (112) is 2.5mm, thickness of the middle section (154) is 3.8mm, and the thickness of the trailing edge (114) is 2mm. As seen in Fig. 5b, in section D-D, the thickness of the leading edge (112) is 2.5mm, thickness of the middle section (154) is 4.2mm, and the thickness of the trailing edge (114) is 2mm. As seen in Fig. 5c, in section E-E, the thickness of the leading edge (112) is 2.5mm, thickness of the middle section (154) is 4.7mm, and the thickness of the trailing edge (114) is 2mm. As seen in Fig. 5d, in section F-F, the thickness of the leading edge (112) is 2.5mm, thickness of the middle section (154) is 5.3mm, and the thickness of the trailing edge (114) is 2mm.
The blade (100) is made of a material selected from a group comprising aluminum, steel, galvanized sheet, compounded polymer, composites and combinations thereof. Further, the blade (100) may be manufactured by a manufacturing process selected from a group comprising casting, molding, fabrication, powder metallurgy, extrusion and metal additive methodology.
Accordingly, the blade of the present invention as disclosed in the present disclosure provides an effective aerodynamic profile which ensures air delivery between 250 and 270 CMM at 320 to 350 RPM, whereby sweep size of the fan is 1200 mm. The fins of the blade reduces turbulence to air cutting, thereby ensuring high efficiency, less noise during the air cutting and high air delivery. Therefore, the blade ensures significant increase in air delivery and noise reduction without increasing the length and width of the blade. Accordingly, the ceiling fan provides more air delivery with less electricity consumption.
Although examples for the present disclosure have been described in language specific to structural features and/or methods, it should be understood that the appended claims are not necessarily limited to the specific features or methods described. Rather, the specific features and methods are disclosed and explained as examples of the present disclosure.

While considerable emphasis has been placed herein on the particular features of this invention, 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 invention. 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 invention herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the invention and not as a limitation.

I/We claim:
1. A blade (100) for a ceiling fan, the blade (100) comprising:
a. a body (110) longitudinally extending between a motor end (120) and a tip
end (130) of the blade (100), and comprising a leading edge (112), and a
trailing edge (114); and
b. a plurality of fins (140) located on the body of the blade (100) protruding from
a top surface of the blade (100), situated proximal to the leading edge (112),
2. The blade (100) as claimed in claim 1, wherein said plurality of fins (140) have a first section (142) proximal to the leading edge (112), a second section (144), and a third section (146) distal to the leading edge (112); and wherein the first section (142), second section (144), and third section (146) in smooth transition to each other.
3. The blade (100) as claimed in claim 1, wherein said fin (140) longitudinally extends transverse to the length of the blade (100).
4. The blade (100) as claimed in claim 1, wherein the first section (142) and third section (146) of the fin (140) has a tapered profile.
5. The blade (100) as claimed in claim 1, wherein fins of plurality of fins (140) has length between 10-40 mm; and width between 1-5 mm.
6. The blade (100) as claimed in claim 1, wherein any two adjacent fins (140) may be equidistant from each other or varying distance from each other.
7. The blade (100) as claimed in claim 6, wherein the distance between any two adjacent fins (140) decreases from the motor end (120) towards the tip end (130).

8. The blade (100) as claimed in claim 1, wherein the body of the blade (100) has an aerofoil profile (150) defined by a leading edge (112), a middle section (154), and a trailing edge (114), and the maximum thickness of the aerofoil (162) is defined at the middle section (154), and minimum thickness is defined at the leading edge (112).
9. The blade (100) as claimed in claim 1, wherein the blade (100) depth is between 3-6 mm increasing towards the tip end (130) from the motor end (120).
10. The blade (100) as claimed in claim 1, wherein the blade (100) twist angle is between 9-12 degrees decreasing from the motor end (120) towards the tip end (130).
11. The blade (100) as claimed in claim 5, wherein leading edge (152) thickness is between 1-3 mm; and trailing edge (156) thickness is between 3-5.5 mm.
12. The blade (100) as claimed in claim 1, wherein blade (100) lift angle is between 5-8 degrees.
13. The blade (100) as claimed in claim 1, wherein blade (100) length is between 635-650 mm.
14. The blade (100) as claimed in claim 1, the blade (100) comprises a joining portion (160) for fixing the blade to a motor assembly, wherein the joining portion has a thickness between 7-11 mm.
15. The blade (100) as claimed in claim 14, the joining portion comprising a plurality of ribs (170) for strengthening the joining portion.
16. The blade (100) as claimed in claim 1, wherein the blade (100) width is between 95-200 mm.

17. The blade (100) as claimed in claim 15, wherein blade (100) width at the tip end (130) is between 95-105 mm, blade (100) width at the motor end (120) is between 110-120 mm, and blade (100) width at the middle section is between 125-135 mm.
18. The blade (100) as claimed in claim 1, wherein air delivery of a plurality of blades (100) mounted on a ceiling fan is between 250-270 CMM at 320-350 RPM, and sweep size is 1200 mm.
19. A ceiling fan (200) comprising a plurality of blades (100) as claimed in claim 1.