FIELD OF INVENTION
The present invention relates to ceiling fan. The present invention in particular
relates to low energy ceiling fan with single phase capacitor start and capacitor
run single phase induction motor.
BACKGROUND/PRIOR ART
Ceiling fans have been used for many years to help circulation of air in rooms.
Ceiling fan lowers the ambient temperature by 4°-5°. Ceiling fans work by
pushing air downwards, creating a breeze that helps cooling skin through
evaporation. The ceiling fan makes a room feel cooler and helps in better
distribution of heat.
The ceiling fan can be classified into single phase capacitor start and capacitor
run induction motor and BLDC motor based ceiling fan.
ICxisting ceiling fans are typically provided with AC induction motors, operating
directly from the utility AC line voltage at high degrees of frequency slip, which
makes operation very inefficient with minimum wattage of 50 watt. Typical
domestic ceiling fans may be optimized for low cost and long life, but not with
electrical efficiency.
Now reference may be made to the following published patents:-
US Patent No. 6,039,541: Ceiling fan blades for low speed fan operation. The
blades have a positive twist at the root motor portion of the blade and a slightly
twisted rounded tip. The chord of the blades taper down from the root to the
rounded tip, and have a tapered airfoil from the aft forward aft edge to the
trailing edge. The airfoil has a combination of a rounded leading edge with
sharp trailing edge, and a square leading edge and rounded trailing edge. The
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bladcs can be twenty inches in length and twenty-six inches in length, and be
used in ceiling fans having two, three, four or more blades in a ceiling mount.
The ceiling fan blades are optimized to operate in ceiling fans running at-low
speed ranges of approximately 50 to approximately 200 revolutions per
minute(rpm) with an enhanced axial airflow. The resultant fan after assembly
with the blades gives the following performance.
• 50 to 200 rpm
» Power~50W
• 6500 CFM Air delivery (184CMM).
Publication No. CN2278106 (Y):The utility model relates to a blade for 1-1.5m
ceiling fan. The cross-sectional shape of the blade from the head to the root is a
cambered surface formed by the gradual smooth transition of two cambered.
surfaces which have different curvature radii. A straight line which is
connected by the tangential points of the two cambered surfaces which have
different curvature radii diverges from the centerline of the blade and crosses
with the centerline of the blade.
US Patent No. 7927071 (B2):It discloses ceiling fan blades with aerodynamical
upper surfaces and wide tip ends for ceiling fans with blades formed from
plastic and/or wood and/or separately attached surfaces that run at reduced
energy consumption and methods of operating the novel ceiling fans blades for
different speeds of up to and less than approximately 250 rpm. The novel
twisted blades can be configured for ceiling fans having any diameters from
less than approximately 32 inches to greater than approximately 64 inch fans,
and can be used in two, three, four, five and more blade configurations.Here,
the blades are having aerodynamic upper surfaces having an upwardly curving
slope from a leading edge to a point of maximum thickness that is closer to the
leading edge than to a trailing edge.
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US Patent No. 6659721 (Bl): Ceiling fan blades for maximizing air flow at
operational speeds of up to approximately 200 revolutions per minute (rpm)
with an airflow of 6500 CFM (184 CMM). The blades have a positive twist at the
tip ends of approximately 5 degrees to approximately 10 degrees parallel to the
ceiling. The root end of the blades closest to the motor can have a positive twist
exceeding that of the tip end and can be approximately 20 to approximately 35
degrees parallel to the ceiling. The ceiling fans can have individual blade
lengths of approximately 20 inches and overall spans of up to approximately 52
inches and up to approximately 54 inches. Each embodiment can use three,
four, and five blades, with the blades being made of injection molded
plasticand the like. The embodiments can include built in light kit domes.
There are a number of ceiling fans available in the market which have sweep of
1200mm and require single phase ac only. However these fans consume power
of 50 watt or more,which render the same less energy efficient.
Thus, from the above it can be concluded that, ceiling fans with capacitor start
and capacitor run single phase induction motor require higher input wattage
and therefore the energy consumption is also very high. For an AC induction
motor, significant losses are incurred by generating the rotor magnetic poles,
^h7crrare"fc^TfTe^ "line: supply?
While rotor losses occur in all AC induction motors, they form a higher
proportion of total losses in a ceiling fan motor because of the relatively low
mechanical shaft power. In addition to consuming excessive electricity, the
wasted energy is largely dissipated as heat causing substantial temperature
rise within the motor, particularly at low speeds where the airflow is
substantially reduced.
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According to IS 374:1979 and schedule 8 of BEE standard, ceiling fans having
minimum air delivery of 210 CMM with lesser energy consumption
(Approximately 40 watt) are considered best.
Ceiling fans based on BLDC motors aim to achieve the above mentioned
specifications by BEE. Ceiling fans based on BLDC motors are highly efficient
and reliable with longetivity (no brush and commutator erosion). BLDC motors
reduce the noise associated with the fan; eliminate the ionizing sparks from the
commutator, reduce the power consumption and thus overall reduce the
electromagnetic interference (EMI). However, there are certain disadvantages of
BLDC motors as they require complex electronic speed controllers to run.
Secondly, it is not practically adopted for using the BLDC motors in the
commercial sector, that is the volume based cost reductions. Further, they are
quite expensive.
However, till date no efforts have been made for providing a ceiling fan with
single phase capacitor start and capacitor run induction motor that fulfills the
above criteria.
Therefore the present invention has been introduced to reduce the energy
consumption of a ceiling fan as compared to the conventional ceiling fans
employing capacitor start and capacitor run single phase induction motor and
at the same time maintaining superior air flow.
OBJECTS OF THE INVENTION
The principal object of the present invention is to provide a low energy
consuming ceiling fan operating on single phase capacitor start and capacitor
run induction.motor.
Another object of the present invention is to provide a low energy consuming
ceiling fan which overcomes disadvantages associated with the prior art.
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Yet another object of the present invention is to provide a ceiling fan having
superior aerodynamic feature to provide maximum air flow.
Still another object of the present invention is to provide a more efficient ceiling
fan by reducing the stator and rotor core losses of the motor to reduce the
power consumption.
SUMMARY OF THE INVENTION
According to this invention, there is provided a low energy ceiling fan with
single phase capacitor start and capacitor run single phase induction motor
comprises an optimized motor to reduce stator and rotor core losses and
optimized fan blade having a wedge profiled longitudinal flat member, width of
which increases towards tail end from mounting end.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Further objects and advantages of this invention will be more apparent from
the ensuing description when read in conjunction with the accompanying
drawings of exemplary embodiments of invention and wherein:
lug. 1 shows:
Fig. 2_shows^
Fig. 3 shows:
Fig. 1 shows:
Fig. 5 shows:
Fig. 5A shows:
Fig. 6 shows:
Fig. 7 shows:
lug. 8 shows:
Top cover of ceiling fan;
Bottom cover of ceiling fan; , __
Different parts of ceiling fan.
Motor assembly of ceiling fan.
Stator stack of present invention.
Rotor according to present invention.
Fan blade in accordance with present invention.
Dispersing area of existing fan blade.
Dispersing area of fan blade of present invention.
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DETAIL DESCRIPTION OF THE INVENTION WITH REFERENCE TO THE
ACCOMPANYING DRAWINGS
The present invention consists of teaching regarding an energy efficient ceiling
fan with single phase capacitor start and capacitor run single phase induction
motor constituting a low power consuming ceiling fan.
The invention particularly has provision for a low power consuming ceiling fan
with sweep 1200mm and output of 210 CMM in accordance to IS-374:1979
arid Schedule 8 of B.E.E i.e minimum 210 CMM, together with the single phase
capacitor start and capacitor run single phase induction motor without
restricting scope of the invention to the same.
The ceiling fan comprises a specially devised motor having stator and rotor
assembly in which the motor is covered by means of top and bottom cover and
in connection with a plurality of novel blades.
Fans are being optimized with respect to blade profile and rotor and stator
assembly in order to provide optimum performance, which will be discussed
hcrcinbelow.
The motor is placed between top cover (fig. 1) and bottom cover (fig. 2).
Referring to fig. 3 reflecting various parts of ceiling.fan-as-follows:-- —
Top canopy-1
Down Rod-2
Bottom canopy-3
Top cover-4
Blade-5
Bottom cover-6
Rotor-7
Stator assembly-8
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Now, reference may be made to fig. 4 indicating motor assembly. The motor
comprises stator and rotor assembly including winding.
The stator as in fig. 5 comprises multitude of laminations constituting a stack
thereof. Each lamination has multiple slots including a plurality of slots along
the inner periphery of said lamination forming main slots and auxiliary slots
surrounded by the main slots. Said main and auxiliary slots accommodate
windings.
The stator of invention is optimized to provide optimum slot area and slot
profile in each lamination for minimum stator losses and to establish greater
magnetic linkage with the rotor.
According to the invention conducting wire such as copper wire of diameter 29
SWG to 35 SWG is used, which is preferably 33 and 34.5 SWG with turns
ranging from 250 to 400, preferably 380 and 280 turns for main and auxiliary
windings respectively.
Reference may be made to fig. 5A illustrating rotor designed according to the
present invention. The rotor comprises a stack of rings, wherein each ring is
provided with a plurality of slots (S). In order to reduce the rotor losses the
profile of said rotor slots is designed to have minimum opening area (A). The
slot is preferably arc shaped without restricting scope of the invention to the
same. Thus, other profiles of slot giving rise minimum opening area which are
readily apparent to a person skilled in the art are understood to be within the
purview of the invention.
Stack of stator with winding thus obtained is housed within the stack of rotor
t.o form the motor. Here, the stator and rotor height is optimized in the range of
14-20 mm preferably 18mm in order to minimize the losses. However, the.same
can be increased to further reduce the stator/rotor losses by simultaneously
balancing with the weight of stator/rotor.
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Furlher, the rotor and stator assembly is made of a electrical steel, which is
made without special processing to control crystal orientation and having
silicon level of 2-3.5% and its magnetic properties are preferably similar in all
directions i.e. it is isotropic such that the material is having a core loss of upto
r\.'( watts. Thus any other material involving core loss of upto 4,7 watts is
applicable to the invention.
.For innovative blade of invention, reference may be made to fig. 6, wherein the
blade comprises a wedge shaped longitudinal flat member, width of which
increases towards tail end (T) from mounting end (M). The blade has flat and
planer upper and lower surfaces. Thickness of the blade is same as the
thickness of the blade sheet unlike prior art because conventional blade has
higher thickness owing to bent structure of the blade.
The blade is provided with a bending line of approximately 9° at a distance 'd'
from the non cutting edge of blade(N) to obtain optimum result such that the
dispersing area is 10-20% preferably 12% of entire blade area. Further, blades
have a combined angle of 8-10°.
The aforesaid provision of combined angle and dispersing area renders the
blades more aerodynamic and reduces the air drag onto the blade^ which
^vefitLially leads to reduction in the load on the blade. Hence, with the reduced
load on blade the air delivery of 210 CMM is obtained (in accordance to IS
374:1979 and schedule 8 of B.E.E) with lesser energy consumption. The blades
can maintain speed of 250-3 lOrpm.,
Further referring to fig. 7 and 8 regarding air dispersing area of fan blade. It
can be clearly observed from the figure 7 and 8 that the dispersing area in the
existing fan blade is greater than dispersing area of present invention fan
blade, i.e. Di>D2.
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Thus, the fan blade has been developed to have less dispersing area and lesser
air drag as compared to known art. Less dispersing area leads to reduced load
on motor thereby requiring less input by motor, which finally results in low
power consumption.
Advantageous Features '
Less power consumption of Approximately 40 watt.
- Low operating cost.
Low end cost.
Efficiently works with long life span.
- Involves less losses of motor.
Higher air delivery (Higher RPM) with lower wattage. So, it is more
effective.
- Lower air drag and less dispersing area of blade.
- Avoidsuse of complicated technology which facilitates its manufacturing,
without requiring skillful workers.
Environment and user friendly.
- Satisfies the standards according to IS--374:1979 and schedule 8 of B.E.
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:-

We Claim:
1. A low energy ceiling fan with single phase capacitor start and capacitor
run single phase induction motor comprises an optimized motor to
reduce stator and rotor core losses and optimized fan blade having a
wedge profiled longitudinal flat member, width of which increases
towards tail end from mounting end.
2. A low energy ceiling fan with single phase capacitor start and capacitor
run single phase induction motor as claimed in claim 1 wherein the
motor comprises a stator stack to provide optimum slot area and slot
profile in each lamination of the stator.
3. A low energy ceiling fan with single phase capacitor start and capacitor
run single phase induction motor as claimed in. claim 1 or 2 wherein
winding in the slot of stator comprises conducting wire such as copper
wire of diameter 29 SWG to 35 SWG, which is preferably 33 and 34.5
SWG with turns ranging from 250 to 400, preferably 380 and 280 turns
for main and auxiliary windings respectively.
4. A low energy ceiling fan with single phase capacitor start and capacitor
run Single phase induction motor as claimed in any of the preceding
claims wherein the stator stack is accommodated inside rotor having a
plurality of slots, profile of which is.designed to have minimum opening
area, wherein the slot is preferably arc shaped.
5. A low energy ceiling fan with single phase capacitor start and capacitor
run single phase induction motor as claimed in any of the preceding
claims wherein the stator and rotor height is optimized in the range of
14-20 mm preferably 18mm in order to minimize the losses.
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6. A low energy ceiling fan with single phase capacitor start and capacitor
run single phase induction motor as claimed in claim 5 wherein the
stack height can be increased to further reduce the stator/rotor losses by
balancing with the weight of stator/ rotor.
7. A low energy ceiling fan with single phase capacitor start and capacitor
run single phase induction motor wherein the rotor and stator assembly
is made of a material such as electrical steel having silicon of 2-3.5%
such that.the material is having core losses of upto 4.7 watts.
8. A low energy ceiling fan with single phase capacitor start and capacitor
run single phase induction motor wherein the blade has flat and planer
upper and lower surfaces, which is provided with a bending line of
approximately 9° at a distance from the non cutting edge of blade such
that the dispersing area is 10-20% preferably 12% of entire blade area.
9. A low energy ceiling fan with single phase capacitor start and capacitor
run single phase induction motor wherein the blade has a combined
angle of 8-10°.
.10. A low energy ceiling fan with single phase capacitor start and
capacitor run single phase induction motoras claimed in any of the
""preceding claims is associated with the advantageous features such as
herein described.