Description:FIELD OF INVENTON
This invention relates to an improved electric motor for a submersible water pump.
More particularly, this invention relates to novel constructional design of an electric
motor and its components used for a submersible pump to reduce the weight of
stainless steel material in the electric motor.
BACKGROUD OF THE INVENTION
An electric motor is an electrical machine that converts electrical energy into
mechanical energy in the form of rotational movement. Generally, an electric motor
comprises a motor housing (shell), a stator mounted on an inner wall of the motor
housing, and a rotor located at the centre of the stator. The stator comprises winding
coils. The rotor comprises magnets and spins at high speeds, providing rotational
mechanical energy to the system. The electric motor used for the submersible pump
requires special construction, like shape and size. These motors have a cylindrical
shape, a small diameter, and a long length due to the requirement for the insertion of
the submersible pump in a bore-well. The submersible motor comprises a motor
housing in the form of a cylindrical tube (shell), a stator attached to the inner diameter
of the shell at a central location, both ends of the shell are covers and sealed by the
end shields and a rotor is supported between the two end shields and located at the
radially central position of the shell. Normally the submersible motor is placed vertically
in the bore well.
According to one prior art of submersible motors, all outer components of the motor
(namely outer shell, top end shield, bottom end shield etc), which are under direct
contact with the bore well water, are made of stainless steel material to prevent rusting.
Out of these parts, the bottom end shield is bolted on the outer shell through locking
plate and circlip. Swivel, mounted on bottom end shield, supports the rotor shaft axially
and the bottom end shield also supports the diaphragm of the motor. Therefore the
bottom end shield is the heaviest by its construction. The bottom end shield is made
of solid stainless steel block. It contributes about 26.5 % weight of total stainless steel
components used in the motor. The stainless steel material is very costly. Hence the
total cost of these submersible motors is very high.
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OBJECT OF THE INVENTION
The object of the invention is to solve the above mentioned problems of the
submersible pump. More particularly, the object of the invention is to provide an
electric motor for a submersible pump with less weight of stainless steel material.
Another object of the invention is to design an electric motor with less use of stainless
steel material.
Another object of the invention is to design an electric motor for a submersible pump
having less cost.
SUMMARY OF INVENTION
To avoid the problems mentioned above and achieve the objects, according to one
embodiment of the present invention, the applicant developed an improved electric
motor for the submersible pump, wherein it comprises:
a) A motor outer shell,
b) A stator,
c) A rotor,
d) A top end shield,
e) An intermediate end shield,
f) A bottom end shield
Wherein;
The bottom end shield is comprising at least two parts;
a first part of the bottom end shield is made of material having less corrosive resistance
and
a second part of the bottom end shield is made of material having more corrosive
resistance than the first part.
The material used to make the first part of the bottom end shield is cast iron grade
FG200.
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The material used to make the second part of the bottom end shield is stainless steel
grade SS304.
The first part of the bottom end shield is bolted on the outer shell of the motor through
locking plate and circlip.
Swivel mounted on the first part of the bottom end shield and it supports the rotor shaft
axially.
The second part of the bottom end shield is mounted on the first part of the bottom
end shield by press fitting or interference fit.
A diaphragm is mounted on the second part of the bottom end shield of the motor
through diaphragm plate and internal circlip. The diaphragm prevents the bore well
water to enter inside the motor. The diaphragm also prevents the bore well water to
contact with the first part of bottom end shield. So there is no need to make the first
part of the bottom end shield of more corrosive resistance material like stainless steel.
Hence the first part of the bottom end shield is made of cast iron which is less costly
material. The second part of the bottom end shield is made of more corrosive
resistance martial like stainless steel as it is get exposed to the bore well water. But
the weight of the second part of the bottom end shield is very less.
Thus the total weight of stainless steel used in the motor is reduced by about 20%.
Hence the cost of motor reduced by 15%.
As the diaphragm is directly mounted on second part of bottom end shield of the motor,
its size is more as compared to prior art where the diaphragm is mounted on bottom
end shield. Due to more size of diaphragm, motor can sustain more pressure
difference between inside and outside of motor.
BRIEF DESCRIPTION OF DRAWINGS:
Figure 1 is a pictorial cross section side view of an electric motor of a submersible
pump according to one prior art of the present invention.
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Figure 2 is a pictorial cross section side view of an electric motor of a submersible
pump according to one embodiment of the present invention.
Figure 3 is an exploded view of an electric motor of a submersible pump according to
one embodiment of the present invention.
Figure 4 is a pictorial cross section side view of a bottom end shell of an electric motor
of a submersible pump according to one prior art of the present invention.
Figure 5 is a pictorial cross section view of a first part and second part of bottom end
shield of an electric motor of a submersible pump according to one embodiment of the
present invention.
Figure 6 is a pictorial exploded cross section view of a first part and second part of a
bottom end shield of an electric motor of a submersible pump according to one
embodiment of the present invention.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENT:
Embodiments of the present invention will now be explained with the help of the figures
herein below. All the aspects described herein will be better appreciated and
understood when considered in conjunction with the following description and the
accompanying drawings. It should be understood, however, that the following
descriptions, while indicating preferred embodiments and numerous specific details
thereof, are given by way of illustration and not of limitation. Many changes and
modifications may be made within the scope herein without departing from the spirit
and scope thereof, and the present invention herein includes all such modifications.
Referring to Figure 1 and 4, according to one prior art of the present invention, an
electric motor (1) of a submersible pump comprises; a motor outer shell (2), top end
shield (3), bottom end shield (4), a stator (5) attach to the outer shell (2) from inside,
a rotor (6). The rotor (6) is radially supported at two ends bush bearings. Top bush
bearing (7) is supported on top end shield (3). Bottom bush bearing (8) is supported
on intermediate shield (9) which is attached to the outer shell (2). The rotor (6) is axially
supported on a thrust bearing (10) through a pivot or swivel (11). The swivel (11) is
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centrally supported in the bottom end shield (4). The bottom end shield (4) is attached
to the outer shell (2) through locking plate (12), internal circlip (13) and bolt (17). A
diaphragm (14) is mounted on the bottom end shield (4) through a diaphragm plate
(15) and bolt (18). The electric motor (1) is sealed from all sides and filled with a fresh
water (16). The diaphragm (14) prevents the water (16) inside the motor to come out
and also prevents the bore well water to enter inside the motor (1). The electric motor
(1) is placed vertically in the bore well and dipped in the bore well water almost all the
time. The bore well water contains minerals and heavy chemical contaminants which
can corrode the outer surface of the motor (1) when in contact for long time. Therefore
exposed parts of motor (1) are made of stainless steel to avoid corrosion. These parts
are outer shell of motor (2), top end shield (3), an intermediate end shield (9) and
bottom end shield (4). Out of these bottom end shield (4) as it supports heady rotor (6)
axially and also supports the diaphragm (14) and the diaphragm plate (15). Therefore
the bottom end shield (4) is the heaviest by its construction. The bottom end shield (4)
is made of solid stainless steel block. It contributes about 26.5 % weight of total
stainless steel components used in the motor (1). The stainless steel material is very
costly. Hence the total cost of these submersible motors is very high.
Referring to Figure 2, 3, 5 and 6, according to one embodiment of the present
invention, an electric motor (21) of a submersible pump comprises; a motor outer shell
(22), top end shield (23), bottom end shield (43), a stator (25) attach to the outer shell
(22) from inside, a rotor (26). The bottom end shield is comprising at least two parts;
a first part (41) of the bottom end shield (43) and a second part (42) of the bottom end
shield (43). The rotor (26) is radially supported at two ends bush bearings. Top bush
bearing (27) is supported on top end shield (23). Bottom bush bearing (28) is
supported in intermediate shield (29) which is attached to the outer shell (22). The
rotor (26) is axially supported on a thrust bearing (30) through a pivot or swivel (31).
The swivel (31) is centrally supported in the first part (41) of bottom end shield (43).
The first part (41) of the bottom end shield (43) is attached to the outer shell (22) of
motor (21) through locking plate (32), internal circlip (33) and bolt (37). The first part
(41) and the second part (42) of the bottom end shield (43) are connected to each
other by press fit or interference fit. A diaphragm (34) is mounted on the second part
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(42) of the bottom end shield (43) through a diaphragm plate (35) and internal circlip
(38). The electric motor (21) is sealed from all sides and filled with a fresh water (36).
The diaphragm (34) prevents the water (36) inside the motor to come out and also
prevents the bore well water to enter inside the motor (21). Therefore the bore well
water will not make contact with the first part (41) of bottom end shield (43). Therefore
it is not necessary to make it of costly stainless steel material. Hence the first part (41)
of the bottom end shield (43) is made of material having less corrosive resistance like
cast iron grade FG200, which is very less costly than the stainless steel material.
Additionally first part (41) of bottom end shield (43) is coated with antirust coat. As the
bore well water will make contact with the second part (42) of the bottom end shield
(43), it is necessary to make it of material having more corrosive resistance like
stainless steel of grade SS304. As the second part (42) of the bottom end shield (43)
do not support heavy rotor axially, its size and weight is very less as compared to
bottom end shield (4) of the prior art. The second part (42) of the bottom end shield
(43) is made of stainless steel sheet. Thus the total stainless steel material used in the
motor (1) is reduced and hence total cost of motor is also reduced. Refer figures 4 and
5 for comparison of stainless steel used in prior art motor and as per invention.
As per actual data for 5 HP motor one kg stainless steel is used for the bottom end
shield in the prior art motor; whereas; only 300 gm stainless steel is used and for
second part of bottom end shield in the inventive motor and 600 gm cast iron is used
for first part of bottom end shield in the inventive motor. Total 20 % of stainless steel
material is saved in the inventive motor and total 15 % cost is saved in the inventive
motor.
The applicant also conducted an endurance test for the inventive motor for corrosion
resistance by simulating bore well conditions. The inventive motor completed 1000
hours test and successfully passed for corrosion resistance.
In this arrangement the size of diaphragm (34) can be kept more due to space
availability. Due to more size of diaphragm, motor can sustain more pressure
difference between inside and outside of motor.
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Although the invention has been described with regard to its embodiments, specific
embodiments, and various examples, which constitute the best mode presently known
to the inventors, it should be understood that various changes and modifications, as
would be obvious to one having the ordinary skill in this art, may be made without
departing from the scope of the invention. The scope of the claims should not be
limited by the preferred embodiments set forth in the examples, but should be given
the broadest interpretation consistent with the description as a whole. All changes that
come with the meaning and range of equivalency of the claims are to be embraced
within their scope. , Claims:WE CLAIM:
Claim 1: An improved electric motor (21) for the submersible pump,
wherein it comprises:
a) A motor outer shell (22),
b) A stator (25),
c) A rotor (26),
d) A top end shield (23),
e) An intermediate end shield (29)
e) A bottom end shield (43)
Wherein;
The bottom end shield (43) is comprising at least two parts;
a first part (41) of the bottom end shield (43) is made of material having less
corrosive resistance and
a second part (42) of the bottom end shield (43) is made of material having
more corrosive resistance than the first part.
Claim 2: An improved electric motor (21) for the submersible pump as
claimed in claim 1, wherein; the first part (41) of the bottom end shield (43)
is made of cast iron material and the second part (42) of the bottom end
shield (43) is made of stainless steel material.
Claim 3: An improved electric motor (21) for the submersible pump as
claimed in claim 1, wherein; the first part (41) of the bottom end shield (43)
is made of cast iron material of grade FG200 and the second part (42) of
the bottom end shield (43) is made of stainless steel material of grade
SS304.
Claim 4: An improved electric motor (21) for the submersible pump as
claimed in claim 1, wherein; the first part (41) of bottom end shield (43) is
attached to the outer shell (22) of the electric motor (21).
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Claim 5: An improved electric motor (21) for the submersible pump as
claimed in claim 1, wherein; the first part (41) and the second part (42) of
the bottom end shield (43) are connected to each other by press fit or
interference fit.
Claim 6: An improved electric motor (21) for the submersible pump as
claimed in claim 1, wherein; a diaphragm (34) is mounted on second part
(42) of the bottom end shield (43) through a diaphragm plate (35) and
internal circlip (38).
Claim 7: An improved electric motor (21) for the submersible pump as
claimed in claim 1, wherein; the diaphragm (34) disposed between lower
end of the first part (41) and lower end of the second (42) part of the bottom
end shield (43) to increase volume of diaphragm for sustaining more
pressure difference in the motor (21).