Claims:
1. An improved fan blade comprising:
a blade body including a leading edge, a trailing edge, a proximal end, a distal end, a radial axis, an attack angle, a twist angle a lift angle and a reinforced portion; wherein
the reinforced portion is positioned near the distal end of the blade body including an attack angle opposite to the direction of rotation of the blade

2. The fan blade as claimed in claim 1, wherein the said reinforced portion is positioned on both the edges disposed symmetrically with respect to radial axis.

3. The fan blade as claimed in claim 1, wherein the reinforced portion is positioned near the distal end of the blade body and extending from the low pressure surface at an attack angle of approximately 11 - 15 degrees with respect to the radial axis.

4. The fan blade as claimed in claim 1, wherein the reinforced portion is positioned near the distal end of the blade body and twist angle of approximately 6 - 10 degrees with respect to the radial axis.
5. The fan blade as claimed in claim 1, wherein the fan blade is operated with a lift angle preferably between 10 to 25 degrees.
6. An improved fan blade comprising:
a blade body including a leading edge, a trailing edge, a proximal end, a distal end, a radial axis, an attack angle, a twist angle a lift angle and a reinforced portion; wherein
the reinforced portion is positioned near the distal end of the blade body including an attack angle opposite to the direction of rotation of the blade; and wherein
the reinforced portion includes a plurality of dimples which forms the attack angle and pushes the air.
7. The fan blade as claimed in claim 6, wherein positioning of the dimples are opposite to the direction of rotation of the blade.
8. The fan blade as claimed in claim 6, wherein the said reinforced portion is positioned on both the edges disposed symmetrically with respect to radial axis.
9. The fan blade as claimed in claim 6, wherein the reinforced portion is positioned near the distal end of the blade body and extending from the low pressure surface at an attack angle of approximately 11 - 15 degrees with respect to the radial axis.
10. The fan blade as claimed in claim 6, wherein the reinforced portion is positioned near the distal end of the blade body and twist angle of approximately 6 - 10 degrees with respect to the radial axis.
11. The fan blade as claimed in claim 6, wherein the fan blade is operated with a lift angle preferably between 10 to 25 degrees.
12. A fan including a hub and a plurality of fan blades as claimed in any of the preceding claims.
, Description:FIELD OF INVENTION
The present invention relates generally to fan blades and, more particularly, to modified fan blades design with improved airflow-directing reinforce portion disposed thereon.
BACKGROUND ART
The purpose of a ceiling fan is to move air continuously below against moderate pressures. An operating fan produces apressure rise across the unit because the rotating fan bladesfunction as aerofoils.
Ina ceiling fan, the rotating fan blades experience drag in the directionopposite that of rotation, and experience lift perpendicular tothe plane of rotation. The lift forces produced on the highpressure surface of the aero foil fan blade generate a dischargepressure that results in volume flow of fluid from the surface. Consequently, it is a goal of fan design to develop fan blade geometries that optimize operating characteristics and performance.
In some ceiling fans, flat planar blades are used by inclining the blades at an angle of approximately ten to twenty degrees from the horizontal to displace airflow in a downward direction. These flat blades might not be aerodynamically efficient in some settings. Accordingly, to move a given volume of air, the fan must operate at a higher speed, thereby consuming more electricity. While flat planar blades have been used, attempts have been made to improve upon ceiling fan blade designs.
Generally, the atmospheric air approaches the fan blade on the low pressure inlet side in an axial direction and leaves from the high pressure outlet side with an axial and rotational component due to work done by the impeller torque. Since the purpose of a fan is to move air against ambient pressures, the rotational velocity component is disadvantageous because it reduces the available total pressure generated by a fan to produce volume flow in an axial direction. Notwithstanding the numerous fan designs developed to maximize fan efficiency while minimizing noise, vibration, and cost, a number of problems still exist in fandesign for which adequate solutions have yet to be developed.
For example, like centrifugal fans, suffer from air leakage around the fan blade tips, and between blade tips and fan casings, whichsubstantially reduces fan efficiency, requiring higher rotationalspeeds and more power to produce a giventotal fan pressure or volume flow. This problem is characterizedin that the air passing through the fan reverses directionat the blade tips, flows around the blade tips from the outletsurface to the inlet surface in a countercurrent fashion, andlowers efficiency as fluid discharged from the high pressureside bleeds back to the low pressure side creating vortices,stall conditions, and other turbulent flow characteristics, andfurther increasing undesirable noise and vibration.
A variety of fan systems have been made and used over the years in a variety of contexts. For instance, various ceiling fans are disclosed in U.S. Patent 7284960, entitled “Fan Blades,” U.S. Patent 6244821, entitled “Low Speed Cooling Fan,” U.S. Patent6939108, entitled “Cooling Fan with Reinforced Blade,” and U.S. Design No. D607,988, entitled “Ceiling Fan,”. The disclosures of each of those U.S. patents are incorporated by reference herein. Additional exemplary fans are disclosed in U.S. Patent 8079823, entitled “Fan Blades,” and U.S. Publication 2010/0278637, entitled “Ceiling Fan with Variable Blade Pitch and Variable Speed Control,” the disclosures of which are also incorporated by reference herein. It should be understood that teachings herein may be incorporated into any of the fans described in any of the above-referenced patents, publications, or patent applications.
SUMMARY OF INVENTION
Therefore theconventional fan blades are not capableof redirecting the rotational velocity component to create aradial component, which in effect would push residual air flow in a radialdirection and would form a more collimated and laminarvolume flow from the fan unit.

Accordingly, it would be desirable to provide a fanblade configuration that increases fan efficiency (increasedstatic fan pressure and volume flow at lower speeds and lower power requirements), decreases noise andvibration, and creates a more focused and large air delivery cone angle.

The present invention is generally directed towardimproved fan blades which reduce, minimize, the lacunae and physical parameters discussed in the prior art, and further which increase the radialfluid velocity component and overall fan efficiency.

The air directingblade structures (described hereinafter as "reinforced areas”) are disposed near the distal end (i.e., the tipend) of the fan blades provided herein. The reinforced area are positioned near the distal end of each fan blade, directed towardthe low pressure suction/inlet side, the high pressure discharge/outlet side, or both, and further at a first specifiedangle (attack angle) with respect to the radial axis of the fan blade, a secondspecified angle (twist angle) of thefan blade, and/or at a third specified angle (lift angle) of the fan blade.

In one embodiment, the present invention is directedtoward fan blades including a blade body having a leadingedge, a trailing edge, a proximal end, a distal end, a highpressure surface, a low pressure surface, and a radial axis, anda reinforced portion, such that the reinforced portion is positioned near the distal end of the blade body preferably opposite to the direction of rotation of the blade or on both sides symmetrically at anattack angle with respect tothe radial axis, at a twist angle, and/or at a lift angle with respect to thesurface of the blade.

In another embodiment, the present invention isdirected toward fan blades including a blade body having aleading edge, a trailing edge, a proximal end, a distal end, ahigh pressure surface, a low pressure surface, and a radialaxis, and a reinforced portion, such that the reinforced portion ispositioned near the distal end of the blade body and extendingfrom the low pressure surface at an attack angle of approximately11 - 15degrees with respect to the radial axis, and at an twist angle ofapproximately 6 - 10degrees with respect to the radial axis.

In another embodiment, the present invention is directed toward fan blades including a blade body having a leading edge, a trailing edge, a proximal end, a distal end, a high pressure surface, a low pressure surface, and a radial axis, and a reinforced portion, such that the reinforced portion is positioned near the distal end of the blade body including a plurality of dimples restrictive to the reinforced area which is the widest area of the blade.

Other features and advantages will be apparent from the following description, including the drawings, and from the claims set forth.

BRIEF DESCRIPTION OF THE ACCOMPANTING DRAWINGS

The various described embodiments will hereinafter be described in conjunction with the appended drawings provided to illustrate and not limit the described embodiments, wherein like designations denote like elements, and in which:
Figure 1 (a) illustrates the simulation result showing higher velocity delivering part of blade length in accordance with the present invention;
Figure 1 (b) illustrates the Twist angle, Attack angle and Lift angles of a ceiling fan blade in accordance with the present invention;
Figure 2 illustrates the reinforcement of blade width at relevant location in accordance with the present invention;
Figure 3 illustrates the effect of dimples on golf ball in accordance with the present invention;
Figure 4 illustrates the dimples on the wider area on the blade and cross-section of dimples in accordance with the present invention;
Figure 5 illustrates the fan blades with attack angle vis a vis the direction of rotation in accordance with the present invention.
Figure 6 illustrates the final mounted fan blades with isometric and side view in accordance with the present invention.

Figure 7 illustrates the existingair delivery cone with respect to the fan sweep diameter as 1200mm as an example in accordance with the present invention;
Figure 8 illustrates the improved air delivery cone with respect to the fan sweep diameter as 1260mm as an example in accordance with the present invention;

DETAILED DESCRIPTION
Blade profile – When the fan is simulated using computational fluid dynamics tools it shows how the whole blade performs in pushing air. In one such simulations of current fan blades it can be seen which portion of the full length of the blade is able to push more amount of air as shown in Figure 1. During the simulation process the air characteristics used is as under:
Below table mentions the quality of air in which the fan rotates. The below data is used for conducting fluid dynamic simulations

In this invention a new blade profile has been designed keeping the fluid simulations results as the basis for the mid-range cone angle fan. In the new design, width of the blade has been reinforced at the portion near the distal end as shown in Fig 2 which pushes more air thereby improving aerodynamic efficiency of the blade. This positional increase of blade width is within limits that it does not adversely increase load on the motor and yet provides better air delivery.
It is important for the blades to overcome the air resistance when running at higher speeds at more than 320 revolutions per minute so that the fan does not require higher input power and at the same time overcome the effects of aerodynamic drag. Fan blades have in-built attack angle which is bent downward, when fan rotates at higher RPM the air pressure on the top surface reduces and on the bottom surface the pressure increases. When this happens the air at higher pressure on the bottom tends to rush towards the area with lower pressure (to maintain equilibrium) which is on the top surface of the blade, while doing so the air pushes the blade upwards at tip because the tip is hanging free in the air. Due to this action the blade undergoes a phenomenon called flapping at the tip. Due to this fluttering action the blade does not remain stable in its position while running and thereby reducing its aerodynamic efficiency and increase in noise levels. Also, the uneven pressure around the blade increases drags on the blades due to which electrical efficiency reduces.
In an exemplary embodiment the fan blades includes a blade body having a leading edge, a trailing edge, a proximal end, a distal end, a high pressure surface, a low pressure surface, and a radial axis, and a reinforced portion, such that the reinforced portion is positioned near the distal end of the blade body preferably opposite to the direction of rotation of the blade or on both sides symmetrically at an attack angle with respect to the radial axis, at a twist angle, and/or at a lift angle with respect to the radial axis of the blade.

In another exemplary embodiment the reinforced portion is positioned near the distal end of the blade body and extending from the low pressure surface at an attack angle of approximately 11 - 15 degrees with respect to the radial axis, and at an twist angle of approximately 6 - 10 degrees with respect to the radial axis.

In another exemplary embodiment the reinforced portion is positioned near the distal end of the blade body and extending from the low pressure surface at an attack angle of preferably 11 - 15 degrees with respect to the radial axis, and at a twist angle of preferably 6 - 10 degrees with respect to the radial axis.

This invention solves this problem in a unique way by applying a simple solution that is very effective in solving this problem elsewhere. It is well known the aerodynamic efficiency of golf ball increases substantially by making its surface with dimples on it as shown in Fig 3. The dimples on the surface make the air flowing around it to stick to the ball for longer thereby reducing the drag created by the turbulence behind the ball when it is flying in the air as shown in the figure 4 and 5.
This dimple design has been adopted to reduce drag and flapping of fan blades, as explained earlier the width of the blade as shown in Fig 4, has been increased at a position along the length of the blade where the blade delivers higher velocity, so air slides longer on the blade at this position than anywhere else. So, dimples have been provided right at the reinforced position to reduce drag also reduce the effect of flapping.
Therefore in another exemplary embodiment, the reinforced portion is positioned near the distal end of the blade body including a plurality of dimples restrictive to the reinforced area which is the widest area of the blade.
The uniqueness and simplicity of this solution lies in its manufacturing process, as the blade are made of metal sheets, the dimples have been made using a common sheet metal press operation called embossing. Because of using a well-known press operation dimples can be manufactured with less cost without requiring special manufacturing processes. On the other hand, reduction in flapping and drag, structural stability of the blade improves which helps reduce stresses coming on the joints resulting in improvement in blade life.
So, with the combination of improvements blade leaf profile design and drag reducing dimples design this invention achieves larger air delivery cone angles and delivers air where it is most relevant to people when they are sitting away from the center of the room and on chairs and sofas closer to room walls.
In further embodiment, and in order to increase the cone angle air flow has to happen in mixed type of flow pattern can be achieved by altering one of the aerodynamic aspects of fan which directly impact cone angle which is lift angle. Based on several experiments the lift angle in this invention has been increased to 45o degrees to achieve larger cone angle of around 42o. With this lift angle the blades are oriented in such a way that it creates mixed flow pattern air flow. So, instead of throwing the air right below it, the fan throws air at an angle which reaches larger area in the room and results in increase in air delivery cone angle.
From close to horizontal position when the lift angle is increased to different angles the cone angle also increases with it, but cone angle cannot be said to be directly proportional to the lift angle. This invention also proposes that a mid-range of air delivery cone angle can be achieved by designing smaller lift angles between 10o to 25o. At this range of lift angles, cone angle of around 24o to 28o can be achieved which can be used as a mid-range of air delivery cone angles.
As shown in Fig 5, the location of the dimples on the blade with respect to blade width. It shows that dimples are positioned on the bent side of the blade which forms the attack angle and pushes the air. The positioning of the dimples is opposite to the direction of rotation of the blade.
Example 1:-
AIR FLOW COVERAGE VIS A VIS SPEED
The fig 7 illustrates the air flow coverage and speeds taken from actual product test reports
Air flow coverage of existing fan running as per below configuration
Speed – 377 RPM.
Blade lift angle – 4.5 degrees
Power consumption – 77.5 watts
Coverage area – 5680 square inches
Noise – 64 decibels
The diagram also mentions air delivery cone angles which is 18 degrees.
Example 2:-
Air flow coverage of invention fan running as per below configuration,
Speed– 330RPM
Blade lift angle– 10 degrees
Power consumption – 83 watts
Covering the area– 9140 square inches,
Noise – 63 decibels
Increase in coverage area at floor at 61%with cone angle at 27.7 degrees.
Inventive Step
Improved blade leaf profile design – The design of the blade profiles is usually made for aesthetic purpose in the fan industry and that profile is tweaked a little to obtain minimum performance from it. In this invention the blade profile has been designed for improved aerodynamic performance of the fan. This new blade profile helps increase air delivery at the same input as the current fan blades.
Improved aerodynamics by reduced drag and flapping – with the help of dimples provided on the wider portion of the blade it reduces the effects of differential pressure generated on either side of the blade while running at higher speed. This helps reduce drag and flapping at the blade tip and while doing so improves blade stability resulting in improved life of the blade.
Reduction in noise levels – With the help of combination new blade leaf profile in which the bending of attack angle is provided with sufficient curvature at the bend line and optimum speed for that profile there is a reduction in the overall air cutting noise level of the fan.
Although the foregoing description of the present invention has been shown and described with reference to particular embodiments and applications thereof, it has been presented for purposes of illustration by way of examples and description and is not intended to be exhaustive or to limit the invention to the particular embodiments and applications disclosed. The particular embodiments and applications were chosen and described to provide the best illustration of the principles of the invention and its practical application to thereby enable one of ordinary skill in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. All such changes, modifications, variations, and alterations should therefore be seen as being within the scope of the present invention as determined by the appended claims when interpreted in accordance with the breadth to which they are fairly, legally, and equitably entitled.