Claims:1. A regenerative self-priming pump comprising of an impeller, with multiple blades extending from the stem which separates the two sides of the impeller and provides structural support to the blades, a casing component which is designed to have the inlet and exit ports for fluid being pumped and a bracket to enclose the fluid channel region around the impeller which is attached to the motor rotor shaft by thread and locked to its position by a lock nut.

2. A regenerative self-priming pump as claimed in claim 1 wherein the gap between the parting face on casing as well as parting face in bracket and the impeller is kept at a value of c = 0.1mm by utilizing the thin fluid film across the gap.

3. A regenerative self-priming pump as claimed in claim 1 wherein the casing design is having an inlet port leading to inlet cavity which leads to the channel which continues to the outlet cavity and terminates at outlet port.

, Description:DESCRIPTION OF INVENTION

Field of the invention

[0001] The present invention relates to motor pumps. More particularly the invention relates to a high performance regenerative self-priming pump assembly with a novel design.

Background and the 'prior art'

[0002] A regenerative pump works by the repeated hydrodynamic spiralling of fluid from the vanes of the impeller to the cavity and then back to the next vane in the impeller. Hence the design of the impeller and cavity hold the key to the performance and efficiency of the pump. Several patents including US Patent No. 5409357 and 6296439 reveal impellers with design of blade extending radially outward from the stem of the impeller. But these designs were applicable for axial flow fuel pumps used in automobiles and lack the cavity design which exploit the pressure build-up due to spiralling of fluid to achieve the head and fluid flow rate requirements for domestic freshwater pumping. The proposed design is also capable of handling debris present in the normal fresh water source which the previous inventions were not suitable for.

Summary of the invention

[0003] The present embodiment of the invention showcases a high performing regenerative pump design which is driven by a prime mover preferably an electric motor. The pump design constitutes an improved impeller [1], casing [4] and bracket [7] along with other components in the assembly such as the shaft [8], locknut [9], mechanical seal [10] and O-ring [15]. The impeller [1] is designed with multiple blades [2] extending radially beyond the stem [3] of the impeller [1]. The casing [4] is designed in such way that the various cavities within the casing aid in improving the pumping performance.

Detailed Description of the Invention with drawings

[0004] Figure 1: shows the cross-section view of the pump cut along the plane through shaft axis and vertical axis. The impeller [1] is assembled to a threaded shaft [8] and is held in position by a lock nut [9]. One skilled in the art appreciates the impeller [1] can be mounted onto a threaded or non-threaded shaft [8] using any method of mounting. The shaft [1] rotates the impeller between the volume enclosed by the casing [4] and bracket [7]. The impeller-shaft assembly is positioned in such a way that the impeller [1] is at the centre of the cavity between the casing [4] and bracket [7]. The gap between the parting face [13] on casing [4] and the impeller [1] is kept equal to the gap between the parting face [16] on bracket [7] (Refer figure 5) and the impeller [1] at c = 0.1mm to minimise the pressure losses. The small gap ensures a hydrodynamic bearing effect on the impeller [1] reducing the resistance to rotation. The casing [4] is attached to the bracket [7] using 3 bolts and an O-ring [15] is provided at its mating interface for better sealing. A mechanical seal [10] is tight fitted to the shaft [8] adjacent to the impeller [1] for sealing the gap between the shaft [8] and the bracket [7].

[0005] Figure 2 shows the cross-sectional view of the casing [4] cavity along a plane cutting the shaft axis orthogonally through the midway of the casing. The suction created by the rotation of the impeller forces the fluid to enter the casing through inlet port [5] which then passes through the inlet cavity [17] and reaches the channel [18] where the rotating impeller [1] pressurizes the fluid due to regenerative action and the pressurized fluid exits the channel [18] through the outlet cavity [19]. The partition [12] feature in the outlet cavity [19] separates the air from liquid and the liquid is re-circulated back to the channel [18] for self-priming. When the priming is complete the fluid exits the casing through the outlet port [6] due to the pressure head created by the rotating impeller [1].

[0006] Figure 3. The impeller [1] constitutes of multiple blades [2] which extend radially beyond the stem [3].

[0007] Figure 4 shows the cross-sectional view of the impeller in a diametral plane. As shown in the figure, we have found that for an impeller design with diameter of Di = 64.8mm and width Wi = 7.9mm the best performance was given by 36 blades [2] which extend radially beyond the radially outermost edge of the stem [3] by ti = 3.5mm.

[0008] Figure 5 shows the bracket [7] design with the parting face [16].

[0009] Figure 6, 7, 8 and 9 shows the regenerating action of the pump. The fluid is being pressurized by re-circulating the fluid through different vanes of the impeller [1]. The extended blades [2] improve the performance of the pump by improving the regenerative action by facilitating for the fluid flowlines to spiral around the vanes and casing cavity. Figure 6 and figure 7 show the simplified schematic of flow directions and the computational fluid analysis results of the flow vectors respectively of the fluid being pumped by the impeller [1] across the cross-section of one of the blade [2] vanes. Due to the hydrodynamic design of the cavity [18] and impeller [1] the flow lines follow a smooth spiral reducing flow loss hence improving hydraulic efficiency of the pump. Figure 8 and 9 shows the computational fluid dynamic results of the fluid flow over the impeller [1] and entire pump, respectively. The strands in the figures 8 and 9 represent the approximate shape of the streamlines of the fluid being pumped. The design and assembly of the components in the pump aid in improving the regenerative effect by making fluid follow tight and smooth spiral streamlines.

[0010] Figure 10 shows the performance improvement gained over the existing pump design. The graph is plotted between percentage of pump efficiency and head generated by existing pump and new improved pump coupled to a 0.5 HP induction motor rated for 240V with a declared duty point head of 25 meters. The new pump design was able to achieve 5% to 8.3% improvement in hydraulic efficiency compared to existing pump design.

[0011] The high efficiency of the pump is achieved because of the improvements made in the components of the assembly as well as the improvements made in the assembly of the components. The assembly is done in such way that the clearance between the casing [4] and impeller [1] has been reduced to 0.1mm. Similarly, the clearance between the impeller [1] and bracket [7] has also been reduced to 0.1mm. This assembly design reduced the pressure leak losses in the pump thereby further improving the performance of the pump. One skilled in the art knows the design showcased in the invention is not limited to the dimensional constraints mentioned in the claims. One skilled in the art can scale up or scale down the design of the components and come up with pumps of different pumping capacity. Also, one skilled in the art can appreciate that different manufacturing methods can be used to manufacture the pump components and the components can be manufactured using any material which is suitable to work under the conditions for which the pump is designed for.