Claims:WE CLAIM:
1. A twisted compounded plastic blade of ceiling fan for higher air delivery, covering larger area with less noise comprising a single structure having varying width in the longitudinal direction with a curvature in transverse direction thereof, wherein thickness of the blade on motor side is thicker than other part of the blade.

2. A twisted compounded plastic blade of ceiling fan for higher air delivery, covering larger area with less noise as claimed in claim 1, wherein the ceiling fan is secured to atleast two said blades, which are symmetrical with respect to each other.

3. A twisted compounded plastic blade of ceiling fan for higher air delivery, covering larger area with less noise as claimed in claim 1 or 2, wherein the blade is made of a material having stiffness enough that the blade does not get disfigured in the course of operation, in which the material is such as ABS glass filled.

4. A twisted compounded plastic blade of ceiling fan for higher air delivery, covering larger area with less noise as claimed in any of the preceding claims wherein the blade is longer including length of the shank to maintain same sweep size, all edges of which are curved.

5. A twisted compounded plastic blade of ceiling fan for higher air delivery, covering larger area with less noise as claimed in any of the preceding claims wherein the blade, motor fitting end of which is having thickness of 7-9 mm and thickness for rest of the blade span is 3.5-4.00 mm.

6. A twisted compounded plastic blade of ceiling fan for higher air delivery, covering larger area with less noise as claimed in any of the preceding claims wherein the motor end, front surface of which is flat and back surface is hollow accommodating a plurality of strengthening cross ribs covered by means of a cover.

7. A twisted compounded plastic blade of ceiling fan for higher air delivery, covering larger area with less noise as claimed in any of the preceding claims wherein the motor end directing towards the motor hub is curved and the blade is having a curvature in the transverse direction thereof.

8. A twisted compounded plastic blade of ceiling fan for higher air delivery, covering larger area with less noise as claimed in any of the preceding claims wherein the blade is provided with a lift angle of 7-9º with respect to the horizontal direction and a twist angle of 11-13º for higher air delivery.

9. A twisted compounded plastic blade of ceiling fan for higher air delivery, covering larger area with less noise as claimed in any of the preceding claims wherein the blade is having varying width in the longitudinal direction starting from an intermediate point near to the motor end till the tip of the blade to increase air velocity, in which width of the motor end is larger than that of the tip end.

10. A twisted compounded plastic blade of ceiling fan for higher air delivery, covering larger area with less noise as claimed in claim 9 wherein Ratio of section BB with respect to section AA is between 1.3~1.35:1, Ratio of section CC with respect to section AA is between 1.5~1.55:1, Ratio of section DD with respect to section AA is between 1.55~1.6:1 and Ratio between section AA to widest width between 1:0.6~0.65 as illustrated in fig. 7.

11. A twisted compounded plastic blade of ceiling fan for higher air delivery, covering larger area with less noise as claimed in any of the preceding claims wherein the radius (ɤ1) at the leading edge is less for higher air cutting, the radius (ɤ2) across the width is the highest for smooth flow of already cut air by the leading edge, the radius (ɤ3) of trailing edge is bigger than that of leading edge for smooth flow and to avoid turbulence, the ratio between radius of trailing edge with respect to leading edge is between 1.45~1.50:1 and the ratio between radius of tip of the blade with respect to leading edge is between 10~12:1.
, Description:A twisted compounded plastic blade of ceiling fan for higher air delivery, covering larger area with less noise
FIELD OF INVENTION
[001] This invention is directed to blade particularly a twisted compounded plastic blade of ceiling fan for higher air delivery, covering larger area with less noise.

BACKGROUND/PRIOR ART OF INVENTION

[002] Currently available conventional ceiling fans in a given sweep size are provided with metal bent blade having bending line in longitudinal direction, which gives optimum air delivery.

[003] Further, ceiling fan is also available with plastic blades having flat shape with uniform thickness giving rise the same performance.

[004] However, the drawback associated with the above is that, the fan blade creates air cutting/flappering sound during the operation of fan.

[005] In view of the above, it is required to devise a ceiling fan with higher air delivery and very lesser noise in a given sweep size in comparison to the conventional ceiling fan for user comfort.

OBJECTS OF THE INVENTION

[006] An object of the present invention is to provide a twisted compounded plastic blade of ceiling fan for higher air delivery, covering larger area with less noise.

[007] Another object of the present invention is to provide a twisted compounded plastic blade of ceiling fan for higher air delivery, covering larger area with less noise which obviates shortcomings of the prior art(s).

[008] Further object of the present invention is to provide a twisted compounded plastic blade of ceiling fan for higher air delivery, covering larger area with less noise which enhances aesthetics of the fan with no gap between hub and blade.

[009] Yet another object of this invention is to propose a twisted compounded plastic blade of ceiling fan for higher air delivery, covering larger area with less noise which functions efficiently.

SUMMARY OF THE INVENTION
[0010] According to this invention, there is provided a twisted compounded plastic blade of ceiling fan for higher air delivery, covering larger area with less noise comprising a single structure having varying width in the longitudinal direction with a curvature in transverse direction thereof, wherein thickness of the blade on motor side is thicker than other part of the blade.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
[0011] Further objects and advantages of this invention will be more apparent from the ensuing description when read in conjunction with the accompanying drawings of the exemplary embodiments and wherein:
Fig. 1 shows: A ceiling fan with blades of the present invention.
Fig. 2 shows: Cross sectional view of the fan blade according to present invention.
Fig. 3 shows: Cover for the motor end of the blade in present invention.
Fig. 4 shows: Back surface of motor end of the blade in accordance with the invention.
Fig. 5 shows: Cross-sectional view of the fan blade indicating lift angle (1).
Fig. 6 shows: Cross-sectional view of the fan blade indicating twist angle (2).
Fig. 7 shows: Variable width at different sections of blade across length thereof.

DETAIL DESCRIPTION OF THE PRESENT INVENTION WITH REFERENCE TO THE ACCOMPANYING DRAWINGS

[0012] The instant invention is pertinent to a twisted compounded plastic blade of ceiling fan for higher air delivery, covering larger area with less noise. Now, reference may be made to fig. 1 illustrating a ceiling fan employing fan blade of present invention. The ceiling fan needs to be fitted with at least two blades. The blades are required to be symmetrical with respect to each other in order to prevent turbulence in dynamic condition of the fan.

[0013] The blade is made of a material having stiffness enough that the blade does not get disfigured in the course of operation. The material is such as ABS glass filled (Acrylonitrile, Butadiene and styrene glass) without restricting ambit of the invention to the same. Thus, other materials readily apparent to a person skilled in the art are understood to be within purview of invention.

[0014] Here, it can be observed that there is no provision of shank, hence the blade is longer than the conventional one as it compensates for the shank, thereby maintaining the same sweep size.

[0015] Further, the blade constitutes a single structure, all edges of which are curved.

[0016] Now, reference may be made to fig. 2. The blade has two sides, namely motor side (M) and Tip side (T).

[0017] The motor side (fig. 1), surface of which is in direct contact with the motor hub is having thickness higher than the thickness of rest of the blade i.e. t1>t2. The thickness at the motor fitting end (M) is 7-9 mm and thickness for rest of the blade span is 3.5-4.0 mm. The blade is designed with higher thickness (t1) at the motor end i.e. at blade fitment area so as to withstand the blade static as well as dynamic load without sagging/breaking.

[0018] The thinner thickness of the blade (t2) provides higher air delivery with less air cutting/flappering sound in ceiling fan. The front surface (F) of motor end is flat and back surface (B) is hollow, filling of which with material will lead to sink mark in the blade owing to higher thickness. Hence, it is provided with multiple strengthening cross ribs (R, fig. 4) to fill the hollow space and also to strength the motor end, which is covered with a cover (C, fig. 3) to avoid accumulation of dust in the gap between ribs and to enhance aestheticness as well.

[0019] Now, reference may be made to fig. 4. The motor end (M) is curved and the blade without bending line is curved in the transverse direction as shown in the figure.

[0020] Further, reference may be made to fig. 5. The blade is provided with a lift angle (1) of 7-9º with respect to the horizontal direction for higher air delivery. The lift angle augments the spread of air in ceiling fan.

[0021] Referring to fig. 6 indicating cross section of blade, wherein the blade possesses a twist angle (2) of 11-13º wherein the twist angle is formed between two longitudinal edges of fan blade as shown. This twist angle results in higher air delivery.

[0022] Now, reference may be made to fig. 7 illustrating varying width along the longitudinal direction of the fan starting from an intermediate point near to the motor end till the tip of the blade to increase air velocity, which eventually leads to higher air delivery of fan.

[0023] The blade comprises varying width at various sections (A-A, B-B, C-C, D-D) along length thereof. The width of the motor end is larger than that of the tip end. The details of the fan blade is as follows.

[0024] Ratio of section BB with respect to section AA is between 1.3~1.35:1.

[0025] Ratio of section CC with respect to section AA is between 1.5~1.55:1.

[0026] Ratio of section DD with respect to section AA is between 1.55~1.6:1.

[0027] Ratio between section AA to widest width between 1:0.6~0.65.

[0028] The radius (ɤ1) at the leading edge is less for higher air cutting.

[0029] The radius (ɤ2) across the width is the highest for smooth flow of already cut air by the leading edge.

[0030] The radius (ɤ3) of trailing edge is bigger than that of leading edge for smooth flow and to avoid turbulence.

[0031] Ratio between radius of trailing edge with respect to leading edge is between 1.45~1.50:1.

[0032] Ratio between radius of tip of the blade with respect to leading edge is between 10~12:1.

[0033] The instant invention possesses attractive seamless look with no gap between the hub and blade, which increases aestheticness of the fan.

Advantageous Features

- Efficient functioning
- Higher air delivery
- Improved aesthetics
- Reduction in noise during operation.

[0034] It is to be noted that the present invention is susceptible to modifications, adaptations and changes by those skilled in the art. Such variant embodiments employing the concepts and features of this invention are intended to be within the scope of the present invention, which is further set forth under the following claims:-