TITLE OF INVENTION

Submersible pump

FIELD OF INVENTION

This invention relates to a submersible pump.

BACKGROUND OF INVENTION

Submersible pumps are generally used in oil wells or bore wells to pump out oil

or water, as the case may be. A submersible pump comprises an electric motor

provided with a power cable connecting the electric motor to a power supply

overground. The power cable runs externally of the pump. (US Patents Nos

6022196, 6443780, 6595295, 2002/0050361 and 2002/0092667) Power cable

provided externally of the pump requires extensive insulation and also a

protective sleeve. This increases the cost of the pump considerably. Due to the

externally provided power cable, the pump has to be installed in the oil well or

bore well eccentrically in order to accommodate the cable. Due to eccentricity

between the well and the pump, the motor does not get cooled uniformly due to

the varying volume of water or oil surrounding the motor casing. This adversely

affects the efficiency of the motor and the pump. Besides, while lowering the

pump in the well for installation or after maintenance or while retrieving the

pump from the well for maintenance or repairs, it has to be done with great care

so as to prevent damage to the power cable and/or well due to eccentric

orientation of the pump within the well. In case the cable happens to hit the well

wall the cable and /or the well wall may get damaged. In case of damage to the

cable, it may have to be replaced or repaired. In case of damage to the well, the

well may have to be abandoned and another well may have to be dug. Due to the

constraint of eccentricity between the well and the pump, the pump diameter can

not be increased with capacity of the pump. Therefore, the pump capacity has to

be increased height wise. This increases the number of impeller assembly and the

cost of the pump. Due to the eccentricity between the pump and the well, suction

of fluid also is not uniform thereby correspondingly reducing discharge

efficiency of the pump.

OBJECTS OF THE INVENTION

An object of the invention is to provide a submersible pump comprising an

electric motor provided with a power cable extending internally through the

pump, which does not require extensive insulation and a protective sleeve along

the entire length thereof, thereby simplifying the construction of the cable and

reducing the cost thereof.

Another object of invention is to provide a submersible pump comprising an

electric motor provided with a power cable extending internally through the

pump so as to facilitate installation of the pump concentrically with the well bore.

Another object of invention is to provide a submersible pump comprising an

electric motor provided with a power cable extending internally through the

pump so as to facilitate cooling of the electric motor uniformly and improve the

performance of the motor and the pump.

Another object of invention is to provide a submersible pump comprising an

electric motor provided with a power cable extending internally through the

pump so as to facilitate size increase of the pump diametrically corresponding to

the pump capacity thereby reducing the height and number of the impeller

assembly and overall height of the pump and. thereby the cost.

Another object of invention is to provide a submersible pump comprising an

electric motor provided with a power cable extending internally through the

pump which facilitates uniform suction of the fluid thereby improving discharge

efficiency of the pump .

DETAILED DESCRIPTION OF THE INVENTION

According to the invention there is provided a submersible pump comprising an

electric motor provided with a power cable connecting the electric motor to a

power supply overground, the power cable being internally provided through the

entire pump and starting from the motor and extending internally through the

motor housing into the strainer of the pump through a liquid tight seal provided

in the top end shield of the motor at the periphery thereof and running through

the strainer along the inner wall thereof, the power cable further extending

through the impeller housing of the pump along the length thereof through a

sleeve provided in the impeller housing at the periphery thereof and protruding

out through the top of the impeller housing at the periphery thereof liquid tight,

the power cable further extending to the power supply externally along the

discharge chamber of the pump.

The following is a detailed description of the invention with reference to the

accompanying drawing, in which the sole Figl is a cross sectional view of a

submersible pump according to an embodiment of the invention. The pump (11)

as illustrated in Figure 1 of the accompanying drawings comprises an electric

motor (1), a strainer (2) mounted on the motor (1), an impeller unit (3) mounted

on the strainer (2) and a discharge chamber (4) mounted on the impeller unit (3).

The pump is installed in a well bore marked (12). (5) is a power cable connecting

the electric motor (1) to a power supply (not shown) over ground. The lower end

of the power cable is connected to the stator winding (6) of the motor (1) and

extends internally through the motor housing (7) into the strainer (2) of the pump

via a gland (8) provided in the top end shield (9) of the motor at the periphery

thereof. Suction openings in the strainer are marked (2a). The gland (8) provides

a liquid tight seal to the cable (5). The cable (5) runs through the strainer (2)

along the inner wall thereof and extends further through the impeller housing (3 a)

along the length thereof via a sleeve (10) which is fitted at the top of the impeller

housing (3a) water tight at the periphery thereof. The impellers are marked (3b).

The cable (5) protrudes out through the top of the impeller housing (3a) at the

periphery thereof and further to the power supply along the discharge chamber

(4) of the pump.

According to the invention, the power cable (5) runs through the pump internally

upto the discharge chamber (4). The cable is provided with a protective sleeve

(10) only in the impeller housing where high fluid pressures are encountered.

The other sections of the pump are at atmospheric pressures. Therefore, the cable

(5) does not require extensive insulation and protective sleeve along the entire

length thereof as in the case of the externally extending power cable. This

reduces the cost of the cable and also simplifies its construction. Since the power

cable (5) is extending internally along the length of the pump concentricity

between the pump and the well bore can be maintained in the installed state of

the pump or while lowering the pump into the well bore or retrieving the pump

from the wellbore for maintenance on repairs. Therefore, damage to the cable

and/or well wall is avoided and uniform cooling of the electric motor is achieved.

This increases the performance of the motor and pump. Due to concentricity

between the pump and the wellbore the suction of fluid is uniform thereby

improving discharge efficiency of the pump. Also the pump size can be

increased diametrically corresponding to capacity thereby reducing the impeller

number and overall height of the pump. This results in further cost saving. The

pump works in known manner. The other details of the pump have not been

illustrated and described as such are not necessary for understanding the

invention.