FORM-2 THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
PROVISIONAL

(See section 10 and rule 13)
MULTI STAGE PUMP


KIRLOSKAR BROTHERS LIMITED
an Indian Company
of Udyog Bhavan, Tilak Road, Pune 411 002,
Maharashtra, India

THE FOLLOWING SPECIFICATION DESCRIBES THE INVENTION.


FIELD OF THE INVENTION: This invention relates to a pump.
Particularly, this invention relates to a multi stage pump.
More particularly this invention relates to impellers fitted on the shaft of the pump.
INTRODUCTION:
A pump is a device used to move liquids from any source location to another location for storage or consumption. Pumps work by using mechanical forces to push the fluid material, by physically lifting, by the force of compression or by centrifugal force.
Pumps fall into two major groups called roto-dynamic pumps and positive displacement pumps. Roto-dynamic pumps are based on bladed impellers which rotate within the fluid to impart a tangential acceleration to the fluid and a consequent increase in the energy of the fluid. The purpose of the pump is to convert this energy into pressure energy of the fluid to be used in the associated piping system.
A positive displacement pump causes a liquid or gas to move by trapping a fixed amount of fluid or gas and then forcing (displacing) that trapped volume into the discharge pipe.
2

In a roto-dynamic pump the impeller is located on the pump shaft and rotates at high speed. In a two stage pump there are two impellers mounted on the same shaft. These impellers are separated by suitably shaped pump casing and the out let of the fist stage is connected to the inlet of the second stage. Both the impellers are mechanically identical but are hydraulically opposite as they have either clock wise or anti clock wise involutes.
Factory fitted impellers are accurately and properly positioned on the shaft and delivers the rated volumetric and pressure capacities of the pump. In a multi stage pump the impellers are located between bearings. When a pump is opened for maintenance activity like changing the bearings the impellers are also released form their mounted position and have to be reassembled on the pump shaft.
On reassembly, accurately positioning the impeller on the shaft is very important. Any error in positioning the impeller, like placing of second stage impeller, in the first stage location, will cause malfunctioning of the pump.
This results in a trial and error type of pump reassembly, causing delay in commissioning of the pump. Any error in proper positioning of the impeller stages will be identified only after the pump is fully assembled and a test is carriedout to ascertain rated performance of the reassembled pump.
In view of the above there is a need to develop a pump shaft and impellers to achieve error free assembly of the impellers.
3

OBJECTS OF THIS INVENTION:
One of the objects of this invention is to provide impellers and pump shaft that can be dismantled and reassembled quickly.
Another object of this invention is to provide impellers and pump shaft that can be dismantled and reassembled even by unskilled workers.
Yet another object of this invention is to provide impellers and pump shaft that can be dismantled and reassembled without affecting the rated hydraulic
performance of the pump.
Yet another object of this invention is to provide impellers and pump shaft that can be dismantled and reassembled without the use of expensive and calibrated tools and measuring instruments.
Yet another object of this invention is to provide impellers and pump shaft that can be easily manufactured.
Yet another object of this invention is to provide impellers and pump shaft that is inexpensive to manufacture.
BRIEF DESCRIPTION OF THE DRAWINGS:
The invention will now be described with respect to the accompanying drawings in which:
4

Figure 1 is a perspective view of conventional impellers and pump shaft assembly of a two stage split case pump;
Figure 2 is a perspective view of a conventional first stage impeller of a two stage split case pump.
Figure 3 is a perspective view of a conventional second stage impeller of a two stage split case pump.
Figure 4 is a perspective view of a conventional pump shaft of a two stage split case pump.
Figure 5 is a perspective view of a pump shaft of a two stage split case pump as per the present invention.
DETAILED DESCRIPTION OF THE DRAWINGS:
Referring to Figure 1, a conventional first stage impeller 12 and a conventional second stage impeller 14 are assembled on the pump shaft 16 of a two stage split case pump. Impellers 12 and 14 have identical internal diameters 24 and 26 (refer figures 2 and 3). These impellers are assembled on the pump shaft 16 in the region 28 (refer figure 4) spaced apart from each other by case-wear rings 18,20 and 22 respectively as clearly seen in figure 1. As the diameter of the pump shaft is the same in region 28 of the shaft 16, there is possibility of wrongly positioning the impellers during re assembly at site conditions.
5

A pump shaft as per this invention is shown in figure 5 wherein region 31 is provided with step diameters 30 and 32 spaced apart by another step diameter 36. The first stage impeller (not specially shown) is provided with a complementary internal diameter matching the step diameter 30 of the pump shaft and the second stage impeller (not specially shown) is provided with a complementary internal diameter matching the step diameter 32 of the shaft. This prevents wrong positioning of the impellers on the pump shaft.
While considerable emphasis has been placed herein on the various components of the preferred embodiment, it will be appreciated that many alterations can be made and that many modifications can be made in the preferred embodiment without departing from the principles of the invention. These and other changes in the preferred embodiment as well as other embodiments of the invention will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the invention and not as a limitation.
Dated this 24th day of June 2008.
Mohan Dewan of R. K. Dewan & Co Applicants' Patent Attorneys
6