FORM 2
THE PATENTS ACT, 1970
(39 OF 1970)
AND
THE PATENT RULES, 2003
COMPLETE SPECIFICATION
(See section 10 and rule 13)
“A FAN BLADE FOR A CEILING FAN”
We, Bajaj Electricals Limited, an 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 THE INVENTION
The present disclosure relates to ceiling fans. More particularly, the present disclosure relates to a fan blade for a ceiling fan with higher air delivery efficiency.
BACKGROUND OF THE INVENTION
This section is intended to provide information relating to the field of the invention and thus any approach or functionality described below should not be assumed to be qualified as prior art merely by its inclusion in this section.
Ceiling fans are commonly known to be used in households and commercial plants, for the purpose of delivery of air in a desired space or room. Ceiling fans are of different types based on the number of fan blades comprised thereof, including, but not limited to a 3-bladed ceiling fan, a 5-bladed ceiling fan, and the like. A ceiling fan is known to comprise a fan motor housed within a fan motor housing, at least a fan blade attached to the fan motor housing, a down-rod arrangement adapted for mounting of the ceiling fan to the ceiling of the desired space or room, and an electrical connection arrangement adapted to enable the operation of the ceiling fan thereof. A structure and arrangement of the ceiling fan is known to a person skilled in the art, and therefore, it is not repeated herein for the sake of brevity.
In operation, the fan motor is actuated by means of an input power, rotating the fan motor housing thereof, such that the rotational motion of the fan motor housing translates to a rotational motion of the fan blade. The fan blade of the ceiling fan pushes the air downwards to increase the velocity of the air, while the ceiling fan is in operation. The fan blade is made up of any conventionally known metal, and defines a trailing edge, and a leading edge opposite the trailing edge. The leading edge and trailing edge are the two opposite edges along the length of the fan blade. Particularly, the leading edge of the fan blade is adapted to engage and cut ambient air, while the trailing edge of the fan blade is adapted to push the ambient air downwards therefrom. Additionally, the conventionally known fan blade defines a connecting end adapted to connect the fan blade to the fan motor housing, and a tip end opposite the connecting end. The conventionally known fan blade is one of a

curved shape fan blade, a side bent fan blade having uniform width, and the like. However, the specific shape of the conventionally known fan blade results in vortices at the tip end thereof, which further results in energy loss of the fan motor. In other words, this reduces the efficiency of the output delivery of air corresponding to the input power consumption of the ceiling fan.
Accordingly, there is a well felt need to provide a fan blade for the ceiling fan, with at least a curved portion of curvilinear form having variable width, capable of enhancing the efficiency of the output delivery of air corresponding to the input power consumption.
SUMMARY OF THE INVENTION
This section is intended to introduce certain aspects of the disclosed invention in a simplified form, and is not intended to identify the key advantages or features of the present disclosure.
In an aspect of the present invention there is provided a fan blade for a ceiling fan comprising: a fan motor housing connecting end; a tip end axially opposite the fan motor housing connecting end; a leading edge; and a trailing edge, wherein at least a part of the fan blade on the trailing edge comprises at least a curved portion of curvilinear form having a variable width.
In an aspect of the present invention, the curved portion of the fan blade is a single continuous curved portion.
In an aspect of the present invention, the angle of the curved portion of the fan blade with respect to the x-y axis of the fan blade is in the range of 10-14˚.
In yet another aspect of the present invention, the width of the curved portion of the fan blade is in the range of 5-50mm.
In another aspect of the present invention, the width of the curved portion of the fan blade at the connecting end is minimum.

In another aspect of the present invention, with width of the curved portion of the fan blade is maximum in at least a point and/or region between the connecting end and the tip end.
In yet another aspect of the present invention, in at least a first region along the length of the fan blade, the width of the curved portion is in the range of 5-30mm, the angle of the curved portion is in the range of 10-13°, and a width of the region is in the range of 100-140mm; in at least a second region along the length of the fan blade [100], the width of the curved portion is in the range of 20-40mm the angle of the curved portion is in the range of 10-13°, and a width of the region is in the range of 95-135mm; in at least a third region along the length of the fan blade [100], the width of the curved portion is in the range of 30-50mm, the angle of the curved portion is in the range of 10-13°, and a width of the region is in the range of 90¬130mm; in at least a fourth region along the length of the fan blade [100], the width of the curved portion is in the range of 30-45mm, the angle of the curved portion is in the range of 11-14°, and a width of the region is in the range of 85-125mm; or in at least a fifth region along the length of the fan blade [100], the width of the curved portion is in the range of 45-10mm, the angle of the curved portion is in the range of 11-14°, and a width of the region is in the range of 80-120mm.
In still another aspect of the present invention, the first, second, third, fourth, and fifth region are adjacent to each other.
In yet another aspect of the present invention, the first region is proximal to the fan motor housing connecting end.
In an aspect of the present invention, the width of the fan blade is in the range of 80-140mm.
In another aspect of the present invention, the fan blade width at the connecting end is in the range of 100-140mm, and the fan blade width at the tip end is in the range of 80-120mm.

In still another aspect of the present invention, the length of the fan blade is in the range of 500-550mm providing fan sweep size as 1200mm.
In yet another aspect of the present invention, the fan blade is made of a material selected from the group consisting of aluminum, galvanized metals, and metal alloys.
In an aspect of the present invention, the fan blade has a lift angle in the range of 3-8˚.
In another aspect of the present invention, there is provided a fan comprising at least a fan blade, the fan blade comprising: a fan motor housing connecting end; a tip end axially opposite the fan motor housing connecting end; a leading edge; and a trailing edge, wherein at least a part of the fan blade on the trailing edge consists of at least a curved portion of curvilinear form having a variable width.
The present disclosure further relates to a fan comprising at least one fan blade as disclosed hereinabove.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
The present invention, both as to its organization and manner of operation, together with further objects and advantages, may best be understood by reference to the following description, taken in connection with the accompanying drawings. These and other details of the present invention will be described in connection with the accompanying drawings, which are furnished only by way of illustration and not in limitation of the invention, and in which drawings:
Figure 1A illustrates a top view of a fan blade, in accordance with the concepts of the present disclosure.
Figure 1B illustrates a side view of the fan blade, in accordance with the concepts of the present disclosure.

Figure 1C illustrates a top view of the fan blade, indicating sections along a length of the fan blade, in accordance with the exemplary embodiment of the present disclosure.
Figure 1D illustrates sectional views of a second section (B), a third section (C), a fourth section (D), and a fifth section (E) of the fan blade, in accordance with the exemplary embodiment of the present disclosure.
Figure 2 illustrates a graph indicating comparative analysis air delivery velocity delivered by the fan blade of the present invention, in accordance with the concepts of the present disclosure.
DETAILED DESCRIPTION OF THE INVENTION
In the following description, for the purposes of explanation, various specific details are set forth in order to provide a thorough understanding of embodiments of the present invention. It will be apparent, however, that embodiments of the present invention may be practiced without these specific details. Several features described hereafter can each be used independently of one another or with any combination of other features. An individual feature may not address any of the problems discussed above or might address only one of the problems discussed above. Some of the problems discussed above might not be fully addressed by any of the features described herein. Example embodiments of the present invention are described below, as illustrated in various drawings in which like reference numerals refer to the same parts throughout the different drawings.
The present invention provides a fan blade [100] for a ceiling fan comprising: a fan motor housing connecting end [102]; a tip end [104] axially opposite the fan motor housing connecting end [102]; a leading edge [106]; and a trailing edge [108], wherein at least part of the fan blade [100] on the trailing edge [108] comprises at least a curved portion of curvilinear form having a variable width. The present invention further provides for a fan [200] comprising at least the fan blade [100] as disclosed hereinbelow.

In a preferred embodiment, the curved portion of the fan blade [100] is a single continuous curved portion. The angle of the curved portion of the fan blade [100], with respect to the x-y axis of the fan blade [100] is in the range of 10-14˚.
In an embodiment, the width of the curved portion of the fan blade [100] is in the range of 5-50mm. In an embodiment, the width of the curved portion of the fan blade [100] is minimum at the connecting end [102]. In another embodiment, the width of the curved portion of the fan blade [100] is minimum at the tip end [104]. In a preferred embodiment, the width of the curved portion of the fan blade [100] tapers towards the connecting end [102] and the tip end [104].
In an embodiment of the present invention, the single continuous curved portion of the fan blade [100] is defined by at least a first region defined along the length of the fan blade [100], wherein the width of the curved portion is in the range of 5¬30mm, the angle of the curved portion is in the range of 10-13°, and a width of the region is in the range of 100-140mm.
In an embodiment of the present invention, the single continuous curved portion of the fan blade [100] is defined by at least a second region defined along the length of the fan blade [100], wherein the width of the curved portion is in the range of 20¬40mm, the angle of the curved portion is in the range of 10-13°, and a width of the region is in the range of 95-135mm.
In an embodiment of the present invention, the single continuous curved portion of the fan blade [100] is defined by at least a third region defined along the length of the fan blade [100], wherein the width of the curved portion is in the range of 30¬50mm, the angle of the curved portion is in the range of 10-13°, and a width of the region is in the range of 90-130mm.
In an embodiment of the present invention, the single continuous curved portion of the fan blade [100] is defined by at least a fourth region defined along the length of the fan blade [100], wherein the width of the curved portion is in the range of 30-

45mm, the angle of the curved portion is in the range of 11-14°, and a width of the region is in the range of 85-125mm.
In an embodiment of the present invention, the single continuous curved portion of the fan blade [100] is defined by at least a fifth region defined along the length of the fan blade [100], wherein the width of the curved portion is in the range of 45¬10mm, the angle of the curved portion is in the range of 11-14°, and a width of the region is in the range of 80-120mm.
In an embodiment, of the present invention, the first region is adjacent to the second region. In an embodiment, the second region is adjacent to the third region. In an embodiment, the third region is adjacent to the fourth region. In an embodiment, the fourth region is adjacent to the fifth region. In an embodiment, the first region is proximal to the fan motor housing connecting end [102].
In an embodiment, the width of the fan blade [100] is in the range of 80-140mm. In an embodiment, the width of the fan blade [100] at the connecting end [102] is in the range of 100-140mm. In an embodiment, the width of the fan blade [100] at the tip end [104] is in the range of 80-120mm. In an embodiment, the length of the fan blade [100] is in the range of 500-550mm providing fan sweep of about 1200mm. In an embodiment, the fan blade is made of a material selected from the group consisting of aluminum, galvanized metals, and metal alloys. In an embodiment, the lift angle of the fan blade is in the range of 5˚. It is understood that a person skilled in the art, based on requirements, will readily be able to select fan blade width, length, and lift angle independently within ranges as disclosed herein, which, by itself alone, for the purposes of the present invention, is not the inventive concept.
The present invention also provides a fan [200] (not shown), comprising at least a fan blade [100] as substantially described herein. In an embodiment, the fan [200] comprises 3 blades [100]. In another embodiment, the fan [200] comprises 4 blades [100]. In yet another embodiment, the fan [200] comprises 5 blades [100].

Known manufacturing processes for stamping of fan blades with variable width fabricated from metal-based substrates are challenging and various shortcoming are associated with it, which make the process cumbersome, inefficient, and inaccurate. The present invention overcomes said challenges in the art to provide the fan blades [100] of the present invention, manufacturing process of which is scalable and efficient.
Figure 1A illustrates a top view of the fan blade [100], while figure 1B illustrates a side view of the fan blade [100], in accordance with the concepts of the present disclosure. Figures 1A and 1B are to be referred to in conjunction with each other, in order to completely understand the concepts of the present disclosure.
As seen in Fig. 1A, the fan blade [100] for a ceiling fan comprises the fan motor housing connecting end [102], the tip end [104], the leading edge [106], and the trailing edge [108]. The tip end [104] is located axially opposite the connecting end [102]. Particularly, the connecting end [102] of the fan blade [100] enables mounting of the fan blade [100] to the fan motor housing (not shown) of the ceiling fan. In a particular non-limiting exemplification, the width of the fan blade [100] at the connecting end [102] is 120mm, while the width of the fan blade [100] at the tip end [104] is 105mm. The leading edge [106] is longitudinally opposite to the trailing edge [108]. The leading edge [106] of the fan blade [100] is adapted to engage with ambient air, while the trailing edge [108] of the fan blade [100] is adapted to push ambient air downwards therefrom. Notably, at least a part of the fan blade [100] on the trailing edge [108] consists of at least the curved portion of curvilinear form having a variable width. For the purposes of characterization of the curvilinear form of the curved portion of the fan blade [100], the fan blade [100] consists of “n” number of sections along the length thereof, wherein n is greater than or equal to two (2), and the single continuous curved portion of curvilinear form having variable width, spans the “n” number of sections.
The curved portion of curvilinear form having a variable width is adapted to provide the enhanced output air delivery corresponding to the input power consumption.

Notably, the curved portion of the fan blade [100] is a single continuous curved portion. An angle of the curved portion with respect to the x-y axis of the fan blade [100] is in the range of 10-14°. A width of the curved portion is in the range of 5¬50mm. Particularly, the width of the curved portion is minimum at each of the connecting end [102] and the tip end [104] of the fan blade [100], while the width of the curved portion is maximum in at least a point and/or region between the connecting end [102] and the tip end [104].
As seen in Fig. 1B, the lift angle of the fan blade [100] is in the range of 3-8˚. In an exemplary example, the lift angle of the fan blade [100] is 5˚.
Figure 1C illustrates a top view of an exemplary embodiment of the fan blade [100] of the present invention, indicating “n” number of sections along the length of the fan blade [100], wherein n = 5. Figure 1D show a sectional side view of the fan blade [100] of a second section (B), a third section (C), a fourth section (D), and a fifth section (E) of the fan blade [100]. Figure 1C and 1D, are to be referred to in conjunction with each other, in order to completely understand the exemplary embodiment of the fan blade [100].
In the exemplary embodiment of the present invention, the value of “n” is equal to 5, such that the fan blade [100] consists of a first section (A), the second section (B), the third section (C), the fourth section (D), and the fifth section (E). Notably, the first section (A) is adjacent to the connecting end [102], and has a width in the range of 100-140mm, preferably 120mm in the exemplary embodiment. The second section (B) is adjacent to the first section (A), and has a width in the range of 95¬135mm, preferably 117m in the exemplary embodiment. The third section (C) is adjacent to the second section (B), and has a width in the range of 90-130mm, preferably 112mm in the exemplary embodiment. The fourth section (D) is adjacent to the third section (C), and has a width in the range of 85-125mm, preferably 107mm in the exemplary embodiment. The fifth section (E) is adjacent to the tip end [104], and has a width in the range of 80-120mm, preferably 102mm in the exemplary embodiment. A structure and specifications of the curved portion of the

fan blade [100], in accordance with the concepts of the present disclosure, will be explained hereinafter in detail.
Along the first section (A) of the fan blade [100], the width of the curved portion is in the range of 5-30mm, preferably 8mm in the exemplary embodiment, and the angle of the curved portion is in the range of 10-13°, preferably 11.8° in the exemplary embodiment. Along the second section (B) of the fan blade [100], the width of the curved portion is in the range of 20-40mm, preferably 28mm in the exemplary embodiment, and the angle of the curved portion is in the range of 10-13°, preferably 11.8° in the exemplary embodiment. Along the third section (C) of the fan blade [100], the width of the curved portion is in the range of 30-50mm, preferably 36mm in the exemplary embodiment, and the angle of the curved portion is in the range of 10-13°, preferably 11.4° in the exemplary embodiment. Along the fourth section (D) of the fan blade [100], the width of the curved portion is in the range of 30-45mm, preferably 39.5mm in the exemplary embodiment, and the angle of the curved portion is in the range of 11-14°, preferably 11.7° in the exemplary embodiment. Along the fifth section (E) of the fan blade [100], the width of the curved portion is in the range of 45-10mm, preferably 36.7mm in the exemplary embodiment, and the angle of the curved portion is in the range of 11-14°, preferably 12.4° in the exemplary embodiment.
Figure 2 shows a comparative analysis of a fan [200] comprising the fan blade [100] of the present invention compared to a fan with blades without curved bend or having a curved bend without variable width. The relationship between air velocity in m/min (X axis) and distance covered in mm (Y axis) shows that the fan blade [100] of the present invention having curved bend with variable width provides maximal air delivery for the same input power as compared to blade without any curved bend or blade having a curved bend of constant width.
Advantageously, the fan blade [100] of the present invention provides increased efficiency of the fan [200], whereby, for the same input power, higher air delivery is achieved. The efficiency is achieved by reducing energy losses at the tip end

[104] and maximizes energy utilization by the middle portion of the blade by reducing vortex formation.
While the preferred embodiments of the present invention have been described hereinabove, it should be understood that various changes, adaptations, and modifications may be made therein without departing from the spirit of the invention and the scope of the appended claims. It will be obvious to a person skilled in the art that the present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive.
LIST OF COMPONENTS
100 – Fan blade
102 – Fan motor housing connecting end
104 – Tip end
106 – Leading edge
108 – Trailing edge
200 – Fan

I/We Claim:
1. A fan blade [100] for a ceiling fan comprising:
a fan motor housing connecting end [102];
a tip end [104] axially opposite the fan motor housing connecting end [102];
a leading edge [106]; and
a trailing edge [108],
wherein at least a part of the fan blade [100] on the trailing edge [108] comprises at least a curved portion of curvilinear form having a variable width.
2. The fan blade [100] as claimed in claim 1, wherein the curved portion is a single continuous curved portion.
3. The fan blade [100] as claimed in claim 1, wherein an angle of the curved portion with respect to the x-y axis of the fan blade [100] is in the range of 10-14˚.
4. The fan blade [100] as claimed in claim 1, wherein a width of the curved portion is in the range of 5-50mm.
5. The fan blade [100] as claimed in claim 1, wherein the width of the curved portion of the fan blade [100] at the connecting end [102] is minimum.
6. The fan blade [100] as claimed in claim 1, wherein the width of the curved portion of the fan blade [100] is maximum in at least a point and/or region between the connecting end [102] and the tip end [104].
7. The fan blade [100] as claimed in claim 2, wherein in at least a first region along the length of the fan blade [100], the width of the curved portion is in the range of 5-30mm, the angle of the curved portion is in the range of 10-13°, and a width of the region is in the range of 100-140mm;

in at least a second region along the length of the fan blade [100], the width of the curved portion is in the range of 20-40mm, the angle of the curved portion is in the range of 10-13°, and a width of the region is in the range of 95-135mm;
in at least a third region along the length of the fan blade [100], the width of the curved portion is in the range of 30-50mm, the angle of the curved portion is in the range of 10-13°, and a width of the region is in the range of 90-130mm;
in at least a fourth region along the length of the fan blade [100], the width of the curved portion is in the range of 30-45mm, the angle of the curved portion is in the range of 11-14°, and a width of the region is in the range of 85-125mm; or
in at least a fifth region along the length of the fan blade [100], the width of the curved portion is in the range of 45-10mm, the angle of the curved portion is in the range of 11-14°, and a width of the region is in the range of 80-120mm.
8. The fan blade [100] as claimed in claim 7, wherein the first, second, third, fourth, and fifth region are adjacent to each other.
9. The fan blade [100] as claimed in claim 7, wherein the first region is proximal to the fan motor housing connecting end [102].
10. The fan blade [100] as claimed in claim 1, wherein a width of the fan blade [100] is in the range of 80-140mm.
11. The fan blade [100] as claimed in claim 10, wherein the fan blade [100] width at the connecting end [102] is in the range of 100-140mm; and the fan blade [100] width at the tip end [104] is in the range of 80-120mm.
12. The fan blade [100] as claimed in claim 1, wherein a length of the fan blade [100] is in the range of 500-550mm providing fan sweep size of 1200mm.
13. The fan blade [100] as claimed in claim 1, wherein the fan blade [100] is made of a material selected from the group consisting of aluminum, galvanized metals, and metal alloys.

14. The fan blade [100] as claimed in claim 1, wherein the fan blade [100] has a lift angle in the range of 3-8˚.
15. A fan [200] comprising at least a fan blade [100] as claimed in claim 1.