SUBMERSIBLE MOTOR WITH IMPROVED DIAPHRAGM

FIELD OF INVENTION

The present invention relates to submersible motors used for pumping fluids from deep down holes. More particularly the invention relates to a diaphragm disposed at the bottom side of the motor shell of the oil filled motors for the purpose of balancing the pressure generated by the oil filled in the motor for lubricating the bearings/cooling the motor and the pressure of the pumping fluid.

DESCRIPTION OF THE PRIOR ART

Submersible motors are adapted to fit within a narrow well bore. Submersible motors are used to power pumps for pumping water and other liquids from underground wells and normally have a relatively long length and small cross-sectional diameter. The Submersible motors are essentially provided with a stator and rotor. The main body of such motors is typically formed from a tubular metal shell or casing. A rotatable drive shaft is mounted along the motor's central vertical axis which is part of the rotor. A coupling end of the drive shaft extends from the top of the motor assembly to provide motive power to a centrifugal pump mounted directly above the motor. In its operative environment, the composite pump and motor assembly lies beneath the surface of the liquid in a well.

The motor of the present invention is of the pre-filled type, i.e., a motor where a sealed cavity in the interior of the motor containing the stator and rotor is filed with a liquid or fill solution such as environmentally safe edible grade oil. When electric power is supplied to the stator windings of the motor, flow of current through the stator windings will generate heat. In combination with the motor housings , this liquid fill solution functions as a heat transfer medium to prevent excessive heat build-up within the motor interior while electrical power is applied to the motor. The liquid is also function as a lubricant for the bearing assemblies used to mount the drive shaft of the motor. Because both heat and friction can shorten the life of a motor, movement of the liquid fill solution within the motor cavity is desirable to aid in heat dissipation and motor lubrication.

Normally in the oil filled motors, a diaphragm is disposed at the bottom side of the motor. The diaphragm is normally surrounded by the oil which is filled in the motor in order to lubricate the bearings/to dissipate the heat generated during the working of the motor. The diaphragm generally comprises an upper closed end and a bottom open end. The diaphragm is placed inside the motor shell such that the upper closed end is placed more or less near the bottom of lower housing. The bottom open end of the diaphragm is held in the required location with the help of the motor base provided with passage opening. The motor base is firmly held in place, for example with the help of a snap ring. The annular gap between the outside of the diaphragm and the motor shell is filled by the oil and the inside of the diaphragm is exposed to the fluid that is being pumped by the pump attached to the motor.

During the working of the motor lot of pressure is generated in the oil and the diaphragm under goes tremendous pressure. There are instants where the pressure damages the diaphragm in due course of time resulting in the draining of the oil from the motor. The absence of the oil inside the motor will cause serious damages such as bearing failure and burnout of the stator winding. In order to replace the bearings and or the stator winding, essentially the motor has to be lifted from the deep well, which is very tiresome, time consuming and expensive. It will be advantageous to provide a diaphragm which will solve the prior art problem.

OBJECTS OF THE INVENTION

It is the primary object of the invention to provide a diaphragm for submersible motors which will withstand the high pressure.

It is another object of the invention to provide a diaphragm which will have more resistance to bursting.

It is another object of the invention, wherein the diaphragm is disposed at the bottom side of the motor shell of the oil filled motors for balancing the pressure generated by the oil filled in the motor for lubricating the bearings / cooling the motor and the pressure of the pumping fluid.

It is another object of the present invention, wherein the diaphragm is in the shape of a bellows, which get compressed and released according to the pressure applied by the oil and the pumping fluid, thereby protecting the diaphragm from getting burst due to the pressure applied by the oil/the pumping fluid.

SUMMARY OF THE INVENTION

Accordingly there is provided a submersible motor comprising:
a stator housed within a motor shell;
a rotor mounted on a shaft;
a bellow shaped diaphragm;
housing comprising one or more bearings disposed to support the shaft of the rotor
within the stator; and
a motor base disposed to retain a diaphragm in position at the bottom portion of the
motor shell,
wherein the bellow portion of the diaphragm gets compressed and released based on
the pressure applied by the oil and the pumping fluid, thereby balancing the pressure
generated.

According to another aspect, the diaphragm comprising:
closed upper portion;
opened bottom portion in the shape of a flange;
cylindrical first portion;
cylindrical second portion;
annular flange portion;
corrugated cylindrical sidewall; and
inside wall;
wherein the annular flange portion connects the cylindrical first portion with the
cylindrical second portion, and
wherein the cylindrical sidewall having a plurality of interleaved outer and inner bends with interconnecting portions disposed to connect the upper portion with the bottom portion.

According to another aspect, the diaphragm is made of flexible, resilient material.

According to yet another aspect, the diaphragm is made of Nitrile butadiene rubber.

According to a further aspect, a portion of the centre upper portion of the diaphragm is provided with additional wall thickness.

According to a still further aspect, the diaphragm ensures that the oil constantly remains in the motor for cooling of the motor and for the lubrication of the bearings.

In the above invention, the motor base is retained in the required position by a snap ring.

BRIEF DESCRIPTION OF THE ACCOMPANYING FIGURES

Figure 1: Illustrates the submersible motor fitted with prior art diaphragm.

Figure 2: Illustrates the submersible motor fitted with diaphragm according to the
present invention.

Figure 3: Illustrates diaphragm according to the present invention in detail.

Figure 4: Illustrates a typical motor shell used in submersible pumps.

Figure 5: Illustrates a typical motor base used in submersible pumps.

DETAILED DESCRIPTION OF THE INVENTION WITH REFERENCE TO THE ACCOMPANYING DRAWINGS

Reference is now invited to accompanying Figure 1 that illustrates a submersible motor, particularly of oil filled type comprising a stator housed within a motor shell. A rotor mounted on a shaft and fitted with antifriction bearings is coaxially mounted within the stator with the help of top and bottom housings. A diaphragm is disposed al the bottom side of the motor shell to balance the pressure generated by the oil filled in the motor for lubricating the bearings/cooling the motor from overheating and the pressure of the pumping fluid.

The submersible motor according to the invention is provided with a diaphragm incorporated with additional means to minimize the failure of the diaphragm and the associated problems, which is apparent from the following part of the description.
Now reference is made to Figures 2, 3, 4and 5 of the drawing accompanying the specification.

At the base portion of the motor, the rotor mounted on a shaft (1) is supported by bearing (2) which is housed in the lower housing (3). The lower housing (3) is fitted to the motor shell (4) at the pre determined location. The motor shell (4) is cylindrical in shape and made of material such as stainless steel. The bottom end of the motor shell (4) is an open one and configured to hold the diaphragm (5) with the help of the annular portion (4a) and the annular guide portion (4b) as shown in figure 4.

The diaphragm (5) according to the invention is a cup shaped bellows and made of flexible, resilient material such as Nitrile butadiene rubber. The diaphragm (5) comprises a closed upper portion (5a), an open bottom portion (5b) in the shape of a flange, a cylindrical first portion (5c), a cylindrical second portion(5d). an annular flange portion (5e) which connect the cylindrical first portion (5c) with the cylindrical second portion(5d), an inside wall (5g) and corrugated generally cylindrical sidewall (5f) having a plurality of interleaved outer and inner bends with interconnecting portions disposed to connect the upper portion (5a) with the bottom portion (5b). In a preferred embodiment approximately 30 to 40 percent of the centre upper portion (5a) is constructed with additional wall thickness. The diaphragm (5) is positioned in the motor shell (4) such that the flange portion (5e) is seated in the annular portion (4a) of the motor shell (4) and the cylindrical second portion(5d) is seated in the annular guide portion (4b) of the motor shell (4) as shown in figure 2.

A motor base (6) is disposed to retain the diaphragm (5) in position. The motor base (6) as shown in figure 5 comprises a flange portion (6a), a cylindrical wall portion (6b) and an inverted hemispherical portion (6c) having a passage opening (6d). The passage opening (6d) is disposed to facilitate the application of the pressure by the fluid being pumped for pressure balance inside the diaphragm (5). While the cylindrical wall portion (6b) of the motor base (6) engages with the inside wall (5g) of the diaphragm (5), the flange portion (6a) of the motor base (6) support the bottom portion (5b) of the diaphragm (5). A snap ring (7) is disposed to retain the motor base (6) in the required position.

ADVANTAGES OF THE PRESENT INVENTION

The diaphragm of the prior art which is made in the shape of a cup is shown in Figure 1 of the drawing accompanying the specification. Comparing the prior art since the diaphragm (5) according to the present invention is constructed in the shape of a bellows, the bellows portion get compressed and released according to the pressure applied by the oil and the pumping fluid. This give total protection to the diaphragm and the diaphragm is protected from getting burst due to the pressure applied by the oil/the pumping fluid and the sequential draining out of the oil from the motor. This ensure that the oil always remain in the motor for proper cooling of the motor as well as for the proper lubrication of the bearings. This minimizes the possible failure of the bearing due to want of lubrication/ burning out of the stator coil due to the absence of the oil inside the motor. Also this eliminates the unnecessary down time and the associated problem in lifting the motor to the surface to attend the replacement of the bearings/stator windings and the associated cost.

WE CLAIM:

1. A submersible motor with improved diaphragm comprising;
a stator housed within a motor shell (4);
a rotor mounted on a shaft (1);
a bellow shaped diaphragm (5);
housing comprising one or more bearings (2) disposed to support the shaft (1) of the
rotor within the stator; and
a motor base (6) disposed to retain a diaphragm (5) in position at the bottom portion
of the motor shell (4),
wherein the bellow portion of the diaphragm gets compressed and released based on
the pressure applied by the oil and the pumping fluid, thereby balancing the pressure
generated.

2. The submersible motor with improved diaphragm as claimed in claim 1. wherein
the diaphragm (5) comprising:
closed upper portion (5a);
opened bottom portion (5b) in the shape of a flange; cylindrical first portion (5c); cylindrical second portion(5d); annular flange portion (5e); corrugated cylindrical sidewall (5f); and inside wall (5g);
wherein the annular flange portion (5e) connects the cylindrical first portion (5c) with the cylindrical second portion (5d), and
wherein the cylindrical sidewall (5f) having a plurality of interleaved outer and inner bends with interconnecting portions disposed to connect the upper portion (5a) with the bottom portion (5b).

3. The submersible motor with improved diaphragm as claimed in claims 1 and 2, wherein the diaphragm (5) is made of flexible, resilient material.

4. The submersible motor with improved diaphragm as claimed in anyone of claims 1 to 3, wherein the diaphragm (5) is made of Nitrile butadiene rubber.

5. The submersible motor with improved diaphragm as claimed in anyone of claims Ito 4, wherein a portion of the centre upper portion (5b) of the diaphragm (5) is provided with additional wall thickness.

6. The submersible motor with improved diaphragm as claimed in anyone of claims Ito 5, wherein the diaphragm (5) ensures that the oil constantly remains in the motor for cooling of the motor and for the lubrication of the bearings.

7. The submersible motor with improved diaphragm as claimed in claim 1. wherein the motor base (6) is retained in the required position by a snap ring (7).