DESC:FIELD OF INVENTON
This invention relates to an electric motor. More particularly, this invention relates to novel constructional design of an electric motor and its components.

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 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 pump in a bore-well. The 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, lock plates attached to the inner diameter of the shell at both ends, end shields attached to each lock plate at both ends, and a rotor supported between the two end shields and located at the radially central position of the shell.
According to one prior art of motor, each lock plate is attached to each end of the shell with the help of an internal circlip. A groove is provided on the inner diameter of the shell to accommodate the circlip. The thickness of the shell has to be considered more as the circlip groove has to be machined at the shell's inner diameter. The drawback of this arrangement is that, due to the thicker shell, the weight and cost of the shell and motor increases.
According to another prior art electric motor, each lock plate is welded to each end of the shell on the inner diameter. The thickness of the shell may be kept at a lower level, and weight and cost may be saved in this arrangement. But this arrangement also has some drawbacks. The lugs are provided on the lock plate towards the radially inner side, on which the end shield is bolted at the tapped holes of the lugs. These lugs protrude radially inside the shell. Therefore, access space is reduced inside the shell. The winding of coils on the stator is done manually by inserting a hand from the end side of the shell. As the access space is reduced due to protruding lugs, more time is required to do coil winding in the stator stack. Hence, total production efficiency decreases. In the case of burrs or sharp edges at the lock plate profile at protruded lugs, it is dangerous for winders hands. To avoid this, lock plates need to be masked by using tape. Also, the shaping of winding coils cannot be done properly due to limited access. Handling of wounded coils gets more critical due to the chances of insulation breaking.
According to another prior art electric motor, outer surface of the electric motor is exposed to bore well water and are prone to corrosion. Therefore, these components are made of a special grade of stainless steel to avoid corrosion. This grade of stainless steel is very costly, which increases the overall cost of the electric motor.

OBJECT OF THE INVENTION
The object of the invention is to solve the above mentioned problems and drawbacks of the electric motor. More particularly, the object of the invention is to design and construct an electric motor with a less complexity.

Another object of the invention is to design and construct an electric motor with a thinner shell to reduce weight and cost.

Another object of the invention is to design and construct an electric motor with increased access to insert the hand of the winder in the shell.

Another object of the invention is to design and construct an electric motor that is safe for the winder to insert his hand in the shell for manual winding.

Another object of the invention is to design and construct and construct an electric motor that requires less time for manual coil winding and increases production efficiency.

Another object of the invention is to design and construct an electric motor that is less costly.

SUMMARY OF INVENTION
To avoid the problems mentioned above and to achieve the objects, the applicant has developed an electric motor, wherein; it comprises:
a motor housing (shell), a stator attached to the inner diameter of the shell at a central location, a weld ring attached to the inner diameter of the shell at both ends, a locking plates having receiving means, an end shield attached to the locking plates at the receiving means with the help of fastening means, bush housings at both ends, having bushes provided between the bush housing and a shaft, a rotor supported between the two end shields and disposed within the shell and the locking plates are slideably attached to inner face of the weld ring, allowing convenient access to perform work within the shell.

According to an embodiment of the invention, the locking plates are attached to inner face of weld ring to slide in radial direction of weld ring.

According to another embodiment of the invention, the weld ring is provided a groove in which the locking plates are slide in radial direction of weld ring.

According to another embodiment of the invention, the receiving means provided on the weld ring are tapped holes.

According to an embodiment of the invention, the height of the locking plate is than the lowest diameter of the weld ring.

According to an embodiment of the invention, the radius of the curved surface of the locking plate is less than the inner radius of the shell.

As the weld ring is welded to the shell, the shell thickness can be kept to a minimum. It reduces the weight and cost of the shell material and, thus, reduces the cost of the motor. As the lowest diameter of the weld ring is sufficiently large and there are no protruded lugs, hence more access space is available to insert the hand of the winder in the shell. Thus, it is safe for the winder to insert his hand in the shell for manual winding. It also reduces time for manual coil winding and increases production efficiency.

According to an embodiment of the invention, the bush housing is sandwiched between the end shields and weld ring with the help of a water-proof arrangement at both ends, so that bore well water in the electric pump is separated from the part of the motor between bush housings at both ends. This part is completely sealed and filled with water.

According to an embodiment of the invention, the bush housing is made of cast iron material. As the bore well water in the pump does not come into contact with the bush housing, so there is no need for a special stainless steel material for the bush housing, which may be made of cast iron material, which costs significantly less than stainless steel. The size of the bush housing of the electric motor is considerably large; hence, the cost savings by using a cast iron bush housing are also significant.

According to an embodiment of the invention, the bush housing is coated with anti-rust coating to avoid corrosion of the cast iron bush housing.

According to an embodiment of the invention, the assembly method of the motor is as follows:
1. the stator is attached to the inner diameter of the shell at an axial central location,
2. the weld ring is attached to the inner diameter of the shell and welded at both ends of the shell,
3. stator coils inside the shell are wounded by inserting a hand through the end of the shell,
4. two locking plates are inserted from each end of the shell at the radially inner position of the shell and inner face of the weld ring.
5. each locking plate is moved radially towards the shell's outer diameter and slides on the inner face of the weld ring,
6. a shaft with a rotor is inserted into the shell from one end and located at the radially central position of the shell.
7. bush housings with bushes are inserted in the shell from both ends, resting axially between the locking plate and end shield and mounted radially between the shell and the rotor shaft,

8. the end shields are attached to the locking plates at the inner tapped holes with the help of bolts at both ends.

With this design of the motor, all the drawbacks faced in the prior arts are eliminated.

BRIEF DESCRIPTION OF DRAWINGS:

Figure 1a, 1b and 1c are pictorial side view, end view and isometric view of an electric motor according to one prior of the present invention.

Figure 2a, 2b and 2c are pictorial side view, end view and isometric view of an electric motor according to another prior of the present invention.

Figure 3a, 3b and 3c are pictorial side view, and end view and enlarged side view of an electric motor according to one embodiment of the present invention.

Figure 4 is a pictorial exploded view of an electric motor according to one embodiment of the present invention.

Figure 5 is a pictorial cut section view of an electric motor according to one embodiment of the present invention.

Figure 6a and 6b pictorial end views and isometric views of locking plate initial and final positions respectively of an electric motor according to one embodiment of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT:

Embodiments of present invention will now be explained with the help of 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 1a, 1b and 1c, according to one prior art electric motor (1), each lock plate (2) is attached to each end of the shell (3) with the help of an internal circlip (4). A groove (5) is provided on the inner diameter of the shell (3) to accommodate the circlip (4). The thickness of the shell (3) has to be considered more as the circlip groove (5) has to be machined at the shell's inner diameter. The drawback of this arrangement is that, due to the thicker shell (3), the weight and cost of the shell (3) and motor (1) increases.
Referring to figure 2, according to another prior art of electric motor (6) , each lock plate (7) is welded to each end of the shell (8) on the inner diameter. The thickness of the shell (8) may be kept at a lower level, and weight and cost may be saved in this arrangement. But this arrangement also has some drawbacks. The lugs (9) are provided on the lock plate (7) towards the radially inner side. These lugs protrude radially inside the shell (8). Therefore, access space is reduced inside the shell. The winding of coils (12) on the stator is done manually by inserting a hand from the end side of the shell. As the access space is reduced due to protruding lugs (9), more time is required to do coil winding in stator stack. Hence, total production efficiency decreases. In the case of burrs or sharp edges at the lock plate profile (13) at protruded lugs (9), it is dangerous for winders hands. To avoid this, lock plates (7) need to be masked by using tape. Also, the shaping of winding coils cannot be done properly due to limited access. Handling of wounded coils gets more critical due to the chances of insulation breaking.
According to another prior art of electric motor, all the components of the electric motor are exposed to bore well water and are prone to corrosion. Therefore, these components are made of a special grade of stainless steel to avoid corrosion. This grade of stainless steel is very costly, which increases the overall cost of the electric motor.

Referring to figures 3 to 6, according to one embodiment of the present invention, an electric motor (21) comprises: a motor housing or shell (22), a stator (23) attached to the inner diameter (37) of the shell (22) at a central location, a weld ring (24) attached to the inner diameter of the shell (22) at both ends, locking keys or plates (26) having receiving means (27). An end shield (28) attached to the locking plates (26) at the receiving means (27) with the help of fastening means (29) at both the ends, a bush housings (30) at both ends, having bushes (31) provided between the bush housing (30) and a shaft (34), a rotor (32) supported between the two bush housings (30) and disposed within the shell (22). This rotor (32) may be located at the radially central position of the shell (22). The locking plates (26) are slideably attached to the inner face of the weld ring (24), allowing convenient access to perform manual work or work with tool within the shell (22).

According to another embodiment of the invention, the weld ring (24) is provided a groove (38) in which the locking plates (26) are slide in radial direction of weld ring (24).

Now, according to an embodiment of the invention, the invention is described, with the assembly method of the electric motor (21), as follows:
1. the stator (23) is attached to the inner diameter (37) of the shell (22) at an axially central location,
2. the weld ring (24) is attached to the inner diameter (37) of the shell (22) and welded at both ends of the shell,
3. stator coils inside the shell are wounded by inserting a hand through the end of the shell (22),
4. two locking plates (26, 26) are inserted from each end of the shell at the radially inner position of the shell (22) and inner face of the weld ring (24),
5. each locking plate (26) is moved radially towards the shell's outer diameter and slides on the inner face of the weld ring (24),
6. a shaft (34) with a rotor (32) is inserted into the shell (22) from one end and located at the radially central position of the shell (22).
7. bush housings (30) with bushes (31) are inserted in the shell (22) from both ends, resting axially between the locking plate (26) and end shield and mounted radially between the shell (22) and the rotor shaft (34),
8. end shields (28) are attached to the locking plates (26) at the tapped holes (27) with the help of bolts (29) at both ends.

According to an embodiment of the invention, the height of the locking plate (26) is slightly less than the lowest diameter (35) of the weld ring (24).

According to an embodiment of the invention, the radius of the curved surface (36) of the locking plate (26) is less than the radius of the shell.

As the weld ring (24) is welded to the shell (22), the shell thickness can be kept to a minimum. It reduces the weight and cost of the shell material and, thus, reduces the cost of the motor (21). As the lowest diameter (35) of the weld ring (24) is sufficiently large and there are no protruded lugs, hence more access space is available to insert the hand of the winder in the shell (22). Thus, it is safe for the winder to insert his hand in the shell for manual winding. It also reduces time for manual coil winding and increases production efficiency.

According to an embodiment of the invention, the bush housing (30) is sandwiched between the end shields (28) and weld ring (24) with the help of a water-proof arrangement at both ends, so that bore well water in the pump is separated from the part of the motor between bush housings (30) at both ends. This part is completely sealed and filled with water.

According to an embodiment of the invention, the bush housing (30) is made of cast iron material. As the bore well water in the pump does not come into contact with the bush housing (30), so there is no need for a special stainless steel material for the bush housing (30), which may be made of cast iron material, which costs significantly less than stainless steel. The size of the bush housing of the electric motor is considerably large; hence, the cost savings by using a cast iron bush housing are also significant.

According to an embodiment of the invention, the bush housing (30) is coated with anti-rust coating to avoid corrosion of the cast iron bush housing (30).

According to an embodiment of the invention, the electric motor (21) mentioned above is used for various applications.

According to another embodiment of the invention, receiving means (27) may be tapped holes or similar arrangements and fastening means (29) may be bolt or similar arrangement.

According to another embodiment of the invention, the electric motor (21) mentioned above is used for a submersible pump.

With above embodiments of the invention the problem mentioned earlier in the electric motor can be solved effectively.

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 meaning and range of equivalency of the claims are to be embraced within their scope.

CLAIMS:WE CLAIM:

Claim 1. An electric motor (21), wherein; it comprises: a motor housing or shell (22), a stator (23) attached to the inner diameter (37) of the shell (22) at a central location, a weld ring (24) attached to the inner diameter (37) of the shell (22) at both ends, locking plates (26) having receiving means (27), an end shield (28) attached to the locking plates (26) at the receiving means (27) with the help of fastening means (29), a bush housings (30) at both ends, having bushes (31) provided between the bush housing (30) and a shaft (34), a rotor (32) supported between the two end shields (28) and disposed within the shell (22) and the locking plates (26) are slideably attached to inner face of the weld ring (24), allowing convenient access to perform work within the shell (22).

Claim 2. An electric motor (21) as claimed in claim 1 wherein; the locking plates (26) are attached to inner face of weld ring (24) to slide in radial direction of weld ring (24).

Claim 3. An electric motor (21) as claimed in claim 2 wherein; the weld ring (24) is provided a groove (38) in which the locking plates (26) are slide in radial direction of weld ring (24).

Claim 4. An electric motor (21) as claimed in claim 1 wherein; the receiving means (27) provided on the weld ring (24) are tapped holes (27) and the fastening means (29) are bolts (29).

Claim 5. An electric motor (21) as claimed in claim 2 wherein; the height of the locking plate (26) is less than the lowest diameter (35) of the weld ring (24).

Claim 6. An electric motor (21) as claimed in claim 2 wherein; the radius of the curved surface (36) of the locking plate (26) is less than the inner radius (39) of the shell (22).

Claim 7. An electric motor (21) as claimed in claim 1 wherein; the bush housing (30) is sandwiched between the end shields (28) and weld ring (24) with the help of a water-proof arrangement at both ends.

Claim 8. An electric motor (21) as claimed in claim 7 wherein; the bush housing (30) is made of cast iron material.

Claim 9. An electric motor (21) as claimed in claim 8 wherein; the bush housing (30) is coated with anti-rust coating.

Claim 10. An assembly method of an electric motor (21), comprises following steps.
a. the stator (23) is attached to the inner diameter (37) of the shell (22) at an axial central location,
b. the weld ring (24) is attached to the inner diameter (37) of the shell (22) and welded at both ends of the shell,
c. stator (23) coils inside the shell (22) are wounded by inserting a hand through the end of the shell,
d. two locking plates (26) are inserted from each end of the shell (26) at the radially inner position of the shell and inner face of the weld ring (24).
e. each locking plate (26) is moved radially towards the shell's outer diameter and slides on the inner face of the weld ring (24),
f. a shaft (34) with a rotor (32) is inserted into the shell (22) from one end and located at the radially central position of the shell (22).
g. bush housings (30) with bushes (31) are inserted in the shell (22) from both ends, resting axially between the locking plate (26) and end shield and mounted radially between the shell (22) and the rotor shaft (34),

h. the end shields (28) are attached to the locking plates (26) at the inner tapped holes (27) with the help of bolts (29) at both ends.