FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
As amended by the Patents (Amendment) Act, 2005
AND
The Patents Rules, 2003 As amended by the Patents (Amendment) Rules, 2005
COMPLETE SPECIFICATION
(See section 10 and rule 13)
TITLE OF THE INVENTION
A radial fan for rotating machines
APPLICANTS :
Crompton Greaves Limited, CG House, Dr Annie Besant Road, Worli, Mumbai 400 030, Maharashtra, India, an Indian Company
INVENTOR (S):
Bhandakkar Parag & Mishra Neetendra both of Crompton Greaves Ltd, Large & Traction Machines Division, D5, Industrial Area MPAKVN, Mandideep, 462046, Madhya Pradesh, India; both Indian Nationals.
PREAMBLE TO THE DESCRIPTION:
The following specification particularly describes the nature of this invention and the manner in which it is to be performed:

Field of the Invention:
This invention relates to the field of electromechanical assemblies.
Particularly, this invention relates to fans.
Still particularly, this invention relates to a radial fan for rotating machines.
Background of the Invention:
Motors are a type of rotating machines / assemblies which convert electrical energy into mechanical energy. Dissipation of heat is a residual factor in this mechanism. For the efficient dissipation of heat, external cooling mechanisms may be employed. This includes coolers, heat exchangers and the like.
With or without heat exchanging or cooling mechanisms, the use and incorporation of fans in motors is imperative for circulation of air. Merely circulating the nearby hot air in an outward fashion (away from motor core) may be enough in some cases, while in other cases, the use of fans for guidance of air towards said heat exchanging or cooling mechanisms is deployed.
Effective guidance of air is typically a factor which depends on the profile of the fan, the blade profile, the radius that the fan covers and the like parameters. Further, noise-related issues are also parameters which are dependent on blade profile. For inducing a laminar flow of air, the blade profile needs to be accordingly designed. The cutting of air or dispersing of air in untoward directions results in turbulence and vortex formation which are undesirable characteristics of an efficient fan.

A further aspect of an efficient fan is its air delivery throughput. E.g. in an exhaust fan, the air from one side is 'pushed' through to the other side, thus creating an 'exhaust' blast of air. In such cases, the fan's efficiency is defined by the amount
parameters of air delivery noise, vibration, and the like fan rating characteristics and measures.
Hence, there is a need for a fan design which
Prior Art:
US5998893 discloses an Integral heat sink and fan rectifier assembly. It mentions the use of a plurality of airfoil shaped fan blades disposed on an outer periphery of the disk forming a fan for cooling the machine.
US5144175 discloses a Cooling fan for electric motors. It reveals airfoil-shaped fan blades.
GB863683 discloses Improvements relating to reversible dynamo-electric machines. It mention5 that it is possible to affix to the rotor fan blades of aerofoil shape which will produce a high efficiency and thus circulate the required volume of air with a substantial minimum of power employed.
However, the targets of greater air delivery at same rpm speed of the fan is not achieved, and with noise curbing characteristics.

In the previous design, there was a problem of high noise and low air delivery in existing fans.
Objects of the Invention:
An object of the invention is to provide a radial fan for use in motors, said fan having relatively increased air delivery rating.
Another object of the invention is to provide a radial fan for use in motors, said fan having relatively lesser noise.
Yet another object of the invention is to provide a radial fan for use in motors, said fan improving air quantity in associated motors.
Summary of the Invention:
According to this invention, there is provided a radial fan for use in rotating machines, said fan comprises:
a. first annular ring of pre-defined width having a first radius, said width of
said first ring sloping outwardly from its inner circumference towards its
outward circumference;
b. second annular ring of pre-defined width having a second radius and being
spaced apart from and co-axial to said first ring, said width of said second
ring sloping outwardly from its inner circumference towards its outward
circumference, said second radius relatively smaller than said first ring;

c. plurality of radially placed intermittently dispersed support elements adapted
to connect said first annular ring to said second annular ring at radially
placed intermittent equidistant locations, said blades being NACA 0012
profiled blades connecting operative back portion of said first annular ring to
operative front portion of said second annular ring, said radially positioned
gaps between said support elements providing an outlet for air; and
d. round plate adapted to be fitted operatively behind said second annular ring
with the help of radially dispersed intermittently located additional support
elements, said round plate being spaced apart from said second annular ring
by means of said additional support elements, said radially positioned gaps
between the additional support elements providing an inlet for air.
Typically, said first annular ring is an outer wrap.
Typically, said second annular ring is an inner wrap.
Typically, said round plate includes a central hub for receiving a shaft for fitting said radial fan.
Brief Description of the Accompanying Drawings:
Figure 1 illustrates an isometric view of the radial fan for motor according to the prior art; and
Figure 2 illustrates a side view of the radial fan of Figure 1.
The invention will now be described in relation to the accompanying drawings:

Figure 3 illustrates a front isometric view of the radial fan;
Figure 4 illustrates a back isometric view of the radial fan;
Figure 5 illustrates a front view of the radial fan;
Figure 6 illustrates a back view of the radial fan;
Figure 7 illustrates a side view of the radial fan;
Figure 8 illustrates a profile of the blade of the radial fan of Figures 3 to 7; and
Figure 9 illustrates a graphical plot of NACA 0012 fan blade.
Detailed Description of the Accompanying Drawings:
Figure 1 illustrates an isometric view of the radial fan for motor according to the prior art.
Figure 2 illustrates a side view of the radial fan of Figure 1.
According to the prior art, there are provided two radial rings (02, 04), coaxial to each other, and spaced apart, with supporting fan blades (06), there-between. This blade (06) is a flat blade, according to the prior art. Reference numeral 07 refers to

air entry and reference numeral 09 refers to air exit. Reference numeral 08 refers to a hub for mounting the radial fan.
According to this invention, there is provided a radial fan (100) for use in rotating machines.
Figure 3 illustrates a front isometric view of the radial fan (100). Figure 4 illustrates a back isometric view of the radial fan (100). Figure 5 illustrates a front view of the radial fan (100). Figure 6 illustrates a back view of the radial fan (100). Figure 7 illustrates a side view of the radial fan (100).
In accordance with an embodiment of this invention, there is provided a first annular ring (12) of pre-defined width having a first radius. The width of the ring slopes outwardly from its inner circumference towards its outward circumference. This is known as an outer wrap.
In accordance with another embodiment of this invention, there is provided a second annular ring (14) of pre-defined width having a second radius. The width of the ring slopes outwardly from its inner circumference towards its outward circumference. The second radius is, typically, smaller than the first radius. This is known as an inner wrap. The second annular ring is spaced apart from the first annular ring. The first annular ring and second annular ring are co-axial rings.
In accordance with yet another embodiment of this invention, there is provided a plurality of radially placed intermittently dispersed support elements (16) adapted

to connect said first annular ring to said second annular ring at radially placed intermittent locations. The support element connect the operative back portion of said first annular ring to the operative front portion of said second annular ring. These support elements are blade elements. The profile of this blade (whose profile is seen in Figure 8 of the accompanying drawings) is in accordance with the blade profile designed in accordance with Airfoil NACA (National Advisory Committee for Aeronautics) 0012 Blade Profile. This blade profile provides radial dispersion of air in an aerodynamic fashion. The characteristics of this blade can be seen in Figure 9 of the accompanying drawings. The radially positioned gaps between the support elements provide an outlet for air.
In accordance with still another embodiment of this invention, there is provided a round plate (18) adapted to be fitted operatively behind said second annular ring with the help of radially dispersed intermittently located additional support elements (20). The round plate is spaced apart from the second annular ring by means of the additional support elements. The radially positioned gaps between the additional support elements provide an inlet for air.
In accordance with an additional embodiment of this invention, the round plate (18) includes a central hub (22) having hub supports (24) for receiving a shaft for fitting said radial fan. Reference numeral 27 refers to air inlet. Reference numeral 29 refers to air outlet.
In this fan, air delivery at the exit has improved and the noise produced by the fan has decreased due to its unique aerofoil (NACA 0012) blade design and improves air quantity in associated motors.

In the prior art, radial fans used in most rotating machines have radial blades which are made typically using 3 to 5 mm thick mild steel sheets. In the design of the prior art, problems of high noise and low air delivery are widely observed. Angle of air delivery was at 90 degrees with respect to air entry. This sharp angle is the cause of noise. The predictions based on the CFD analysis about the fan, according to this invention, are in great congruity with actual test bed results. This has made the of similar fan designs in a wide gamut of rotating machines.
Since it is radial fan, according to this invention, it sucks the air in the axial direction and throws the air at higher velocity in the particular direction in the radial direction. Hence, there is more air delivery at same rpm as compared to prior art.
While this detailed description has disclosed certain specific embodiments of the present invention for illustrative purposes, various modifications will be apparent to those skilled in the art which do not constitute departures from the spirit and scope of the invention as defined in the following claims, and 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

We claim,
1. A radial fan for use in rotating machines, said fan comprising:
a. first annular ring of pre-defined width having a first radius, said width of
said first ring sloping outwardly from its inner circumference towards its
outward circumference;
b. second annular ring of pre-defined width having a second radius and being
spaced apart from and co-axial to said first ring, said width of said second
ring sloping outwardly from its inner circumference towards its outward
circumference, said second radius relatively smaller than said first ring;
c. plurality of radially placed intermittently dispersed support elements adapted
to connect said first annular ring to said second annular ring at radially
placed intermittent equidistant locations, said blades being NACA 0012
profiled blades connecting operative back portion of said first annular ring to
operative front portion of said second annular ring, said radially positioned
gaps between said support elements providing an outlet for air; and
d. round plate adapted to be fitted operatively behind said second annular ring
with the help of radially dispersed intermittently located additional support
elements, said round plate being spaced apart from said second annular ring
by means of said additional support elements, said radially positioned gaps
between the additional support elements providing an inlet for air.
2. A fan as claimed in claim 1 wherein, said first annular ring is an outer wrap.
3. A fan as claimed in claim 1 wherein, said second annular ring is an inner wrap.

4. A fan as claimed in claim 1 wherein, said round plate includes a central hub for receiving a shaft for fitting said radial fan.