FIELD OF INVENTION:
[001] The present subject matter described herein, relates to a ceiling fan, and in particular of fan blade with variable thickness across leading to trailing edge and rotor to tip end with variable twist angle across rotor to tip end for higher air delivery in 1300~1350mm sweep of the ceiling fan.
BACKGROUND AND PRIOR ART:
[002] Generally, ceiling fans in a given sweep size, i.e., approx. 1300mm come with metal blade with bend or curved shape which gives optimum air delivery as per the shape of blade.
[003] There are some plastic blades also available in the ceiling fan with flat / curved shape and uniform / different variable thickness that also gives similar air delivery. Now there is a need to develop a ceiling fan which gives the maximum air delivery in a given sweep with variable thickness as compared to the conventional ceiling fan blades.
[004] It is required to develop and design the profile of the fan blade across section, twist angle, lift angle and width of the blade which gives highest air delivery in its category with lowest noise level as compared to the prior art.
OBJECTS OF THE INVENTION:
[005] The principal objective of the present invention is to provide a variable thickness ceiling fan blade across leading to trailing edge and rotor to tip end.
[001] Another object of the present invention is to provide variable thickness ceiling fan blade for higher air delivery (more than 310-330 CMM) in 1300~1350mm sweep size.
[006] Another objective of the present invention is to provide variable thickness ceiling fan blade for low noise generation in 1300~1350mm sweep.

[007] Yet another objective of the present invention is to provide variable thickness ceiling fan blade for higher air spread.
[008] Yet another objective of the present invention is to design a variable twist angle blade in which maximum twist angle at rotor end and minimum twist angle at tip end.
[009] Yet another objective of the present invention is to design a ceiling fan blade with variable width across leading to trailing edge.
SUMMARY OF THE INVENTION:
[0010] The present subject matter relates to a ceiling fan blade with variable thickness across leading to trailing edge and rotor to tip end with variable twist angle across rotor to tip end for higher air delivery in a sweep size of 1300~1350mm. The ceiling fan blade has defined various sections at GG, FF, EE and DD from the rotor end to the tip end at variable distance from each other, where a section GG to section DD have twist angle in range of 10° - 20°. The variable thickness and twist angle blade is also having the variable width across the length of the blade.
[0011] In order to further understand the characteristics and technical contents of the present subject matter, a description relating thereto will be made with reference to the accompanying drawings. However, the drawings are illustrative only but not used to limit scope of the present subject matter.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] It is to be noted, however, that the appended drawings illustrate only typical embodiments of the present subject matter and are therefore not to be considered for limiting of its scope, for the invention may admit to other equally effective embodiments. 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 embodiments of system or methods in accordance with

embodiments of the present subject matter are now described, by way of example, and with reference to the accompanying figures, in which:
[0013] Fig. 1 illustrates ceiling fan assembly, in accordance with an embodiment of the present subject matter;
[0014] Fig. 2 illustrate cross-sectional view of ceiling fan blade with different lift angles at different length, in accordance with the present subject matter;
[0015] Fig. 3 illustrates variable twist angles, variable thickness, and variable depth of the ceiling fan blade at different cross section points, in accordance with an embodiment of the present subject matter, in accordance with the present subject matter;
[0016] Fig. 4a, 4b, 4c and 4d illustrate twist angles with various cross section of the ceiling fan blade as shown in the fig. 3, in accordance with an embodiment of the present subject matter; and
[0017] Fig. 5 illustrates profile of ceiling fan blade, in accordance with an embodiment of the present subject matter.
[0018] The figures depict embodiments of the present subject matter for the purposes of illustration only. A person skilled in the art will easily 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.
DESCRIPTION OF THE PREFERRED EMBODIMENTS:
[0019] The present subject matter relates to a variable thickness blade across leading to trailing edge and rotor to tip end with variable twist angle and width of the ceiling fan blade in compounded plastic material of for higher air delivery with higher spread in 1300~1350mm sweep ceiling fan. The variable thickness fan blade has defined various sections at GG, FF, EE and DD from the rotor end to the tip end at variable distance from each other, where the section GG to the section DD have twist angle in range of 10° to 20°. Further, the thickness of

variable thickness fan blade across the leading edge to the trailing edge is in range of 2.5mm to 6.0mm.
[0020] It should be noted that the description and figures merely illustrate the principles of the present subject matter. It should be appreciated by those skilled in the art that conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present subject matter. It should also be appreciated by those skilled in the art that by devising various arrangements that, although not explicitly described or shown herein, embody the principles of the present subject matter and are included within its spirit and scope. Furthermore, all examples recited herein are principally intended expressly to be for pedagogical purposes to aid the reader in understanding the principles of the present subject matter and the concepts contributed by the inventor(s) to furthering the art, and are to be constructed as being without limitation to such specifically recited examples and conditions. The novel features which are believed to be characteristic of the present subject matter, both as to its organization and method of operation, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures.
[0021] These and other advantages of the present subject matter would be described in greater detail with reference to the following figures. It should be noted that the description merely illustrates the principles of the present subject matter. It will thus be appreciated that those skilled in the art will be able to devise various arrangements that, although not explicitly described herein, embody the principles of the present subject matter and are included within its scope.
[0022] Fig. 1 illustrates ceiling fan assembly, in accordance with the present subject matter. The ceiling fan assembly 200 has a motor housing 202, a downrod 203, a canopy 204, a down rod cover 205 and a plurality of variable thickness fan blades 100, where each variable thickness fan blade from the plurality of variable thickness fan blades 100 is mounted to the motor housing 202. The Canopy 204

and the down rod cover 205 are designed for matching with the motor housing 202 to make a ceiling fan 201 which is more attractive. The ceiling fan 201 is having 18 Pole outer rotor induction motor with 24mm stack height which is heaviest in its category to rotate the variable thickness fan blade 100 to deliver the high air delivery. The outer diameter of stator is between 136~137mm with copper winding in primary and auxiliary slots. The rotor is having the outer diameter between 160~161mm with total height of 38mm. The rotor is having the aluminium casting by 7mm height on both side and minimum 9mm width.
[0023] Fig. 2 illustrates cross-sectional view of ceiling fan blade with different lift angles at different length, in accordance with the present subject matter. As shown in the figure 2, arrow X indicates horizontal direction or plane and arrow Y indicates vertical direction or plane. The tip end 102 rotates about central axis (Y axis) of the motor during movement of the rotor. Each variable thickness fan blade from the plurality of variable thickness fan blades 100 (hereinafter it can be referred as fan blade 100) comprising a rotor end 101 provided at one end to connect with rotor of the ceiling fan 201 and a tip end 102 provided at distal end of the fan blade 100. The fan blade 100 is thicker at the rotor end 101 tapering down to a thinner at the tip end 102 for providing high lift and low drag. The fan blade 100 is having two different lift angles 110a, 110b at different length of the fan blade 100, wherein the lift angles 110a, 110b in between the rotor end 101 and the tip end 102 is in range 8° to 14° with reference to horizontal axis X of the fan for higher air delivery. The different lift angles 110a, 110b are used to increase the air spread of the ceiling fan 201 without compromising the air velocity.
[0024] Accordingly, the lift angles 110a, 110b of the fan blade 100 directs the air outside the circumference of the fan blade 100 to increase the spread of the air during fan rotation. The fan blade 100 has a unique lift angle in the blade to improve the spread of the air velocity 1080mm from the center of the ceiling fan greater than 15m/sec, wherein the air delivery of the fan blade 100 is in range of more than 310 to 330 CMM.

[0025] Fig. 3 illustrates variable twist angle, variable thickness, and variable depth of the ceiling fan blade at different cross section points, in accordance with an embodiment of the present subject matter. To illustrate optimized parameters and structure of each fan blade from the plurality of fan blades 100, where each fan blade 100 is divided into four sections DD, EE, FF, and GG at distance 100mm, 100mm, 100mm and 207mm from the center of the rotor, respectively. Each fan blade 100 has continued twist angle running from the rotor end 101 to the tip end 102. The twist angle decreases non-uniformly from the rotor end 101 to the tip end 102 along length of the fan blade 100. The twist angle is in range 10° to 20° from the rotor end 101 to the tip end 102. Further, depth of the fan blade 100 at different sections i.e. GG, FF, EE and DD, across the leading edge 103 to the trailing edge 104 is in range of 7mm to 8mm.
[0026] As shown in the figure 4a, the section GG which is closer to the rotor end 101 which has highest twist angle 109 in range 17° to 20°, preferably 18.2°.
[0027] As shown in the figure 4b, the section FF has twist angle 108 is in range 13° to 15°, preferably 13.6°.
[0028] As shown in the figure 4c, the section EE has twist angle 107 is in range 11° to 13°, preferably 11. 3°.
[0029] As shown in the figure 4d, the section DD has lowest twist angle 106 is in range 10° to 11°, preferably 10. 6°.
[0030] Referring to figure 2-4, the fan blade 100 has variable width which increases from the rotor end 101 to the tip end 102. The fan blade 100 is wider at the tip end 102 and narrows down towards the rotor end 101. The thickness at the rotor end 101 is designed to give higher air delivery and to allow blade fitment with the motor shaft and to withstand the blade in static as well as dynamic load without sagging/ breaking.
[0031] Referring to figure 5, illustrate profile of ceiling fan blade, in accordance with an embodiment of the present subject matter. It shows the variable width of the blade from the rotor end 101 to the tip end 102. The variable with of the fan

blade 100 along with the twist angle decide the volume of the air thrown from the particular area of fan blade 100. The width and twist angle are optimized across the fan blade 100 for giving maximum air delivery from the ceiling fan 201 in range 1300~1350mm sweep at speed in range 280-310 RPM. It also shows the rotor end 101 in round shape, which is designed to keep the ceiling fan 201 in seamless aesthetics after installation of all three blades in the motor.
[0032] Although embodiments for the present subject matter have been described in language specific to structural features, it is to be understood that the present subject matter is not necessarily limited to the specific features described. Rather, the specific features and methods are disclosed as embodiments for the present subject matter. Numerous modifications and adaptations of the system/component of the present invention will be apparent to those skilled in the art, and thus it is intended by the appended claims to cover all such modifications and adaptations which fall within the scope of the present subject matter.

We claim:
1. A variable thickness fan blade (100) for high air delivery in a ceiling fan (201), the variable thickness fan blade (100) comprising:
a rotor end (101) provided at one end to connect with rotor of the ceiling fan (201);
a tip end (102) provided at a distal end of the variable thickness fan blade (100); and
a leading edge (103) and a trailing edge (104) defined along longitudinal length of the variable thickness fan blade (100) from the rotor end (101) to the tip end (102);
characterized in that
the variable thickness fan blade (100) has defined various sections at GG, FF, EE and DD from the rotor end (101) to the tip end (102) at variable distance from each other, where the section GG to the section DD have twist angle in range of 10° - 20°-
2. The variable thickness fan blade (100) as claimed in claim 1, wherein thickness of the rotor end (101) is larger than that of the tip end (102).
3. The variable thickness fan blade (100) as claimed in claim 1, wherein the section GG is closer to the rotor end (101) which has twist angle (109) in range of 17° - 20°, the section FF has twist angle (108) in range of 13° -15°, the section EE has twist angle (107) in range of 11° - 13°, and the section DD has twist angle (106) in range of 10° - 12°.
4. The variable thickness fan blade (100) as claimed in claim 1, wherein two different lift angles (110a, 110b) in between the rotor end (101) and the tip end (102) is in range 8° - 14°.
5. The variable thickness fan blade (100) as claimed in claim 1, wherein thickness of variable thickness fan blade (100) across the leading edge (103) to the trailing edge (104) is in range of 2.5mm to 6.0mm.

6. The variable thickness fan blade (100) as claimed in claim 1, wherein depth of the variable thickness fan blade (100) at different sections i.e. GG, FF, EE and DD, across the leading edge (103) to the trailing edge (104) is in range of 7mm to 8mm.
7. The variable thickness fan blade (100) as claimed in claim 1, wherein air delivery of the variable thickness fan blade (100) is in range of more than 310to330CMM.
8. The variable thickness fan blade (100) as claimed in claim 1, wherein sweep size of the ceiling fan (201) is in range 1300mm to 1350mm.
9. The variable thickness fan blade (100) as claimed in claim 1, wherein the ceiling fan is having 18 pole outer rotor induction motor with 24mm stack height which is heaviest in its category to rotate the fan blade (100) at 280-310 RPM to deliver the required air delivery and spread.
10. The variable thickness fan blade (100) as claimed in claim 1, wherein the variable thickness fan blade (100) is PU painted blade across the leading edge (103) to the trailing edge (104) and the rotor end (101) to the tip end (102) and variable twist angle and width of fan blade (100).