ASSEMBLY”

FIELD OF THE INVENTION The present invention relates to an electric water pump with an improved impeller assembly. More particularly, the present invention relates to an improved impeller assembly of an electric water pump that provides compactness, requires less input torque to maintain the flow specification and has an improved overall pump efficiency.

BACKGROUND OF THE INVENTION

Electric water pumps are frequently used in vehicle cabin heating, low pressure exhaust gar recirculation (EGR) cooling, battery cooling etc. as they allow a volume flow rate on demand when a DC voltage supply is provided for the engine and power electronics cooling, battery cooling of hybrid electric vehicle (HEV) or electric vehicle (EV) cars as well as cooling of turbocharged air for passenger cars, light duty or medium duty vehicle.

The water pumps were conventionally driven by a belt attached to the crankshaft of internal combustion engine which takes mechanical power from the engine to circulate coolant through the engine and heater to cool the engine or heat the vehicle's occupant cabin. Afterwards a large number of vehicles shifted towards electrically controlled brushless DC (BLDC) motor-based electric water pump which is driven by an electric motor and is controlled by a controlling unit. The electric/hybrid vehicles require an electrically driven water pump for the cooling of its components and hence there is always a need of efficient and affordable electric pumps for such purpose. Hence, an electric pump becomes a crucial part for the life of components of the electric/hybrid vehicle. For an electric pump to become suitable for such applications, it must meet the flow specifications and should have a high overall pump efficiency.

Generally, in an electric pump, different parts are manufactured and then assembled together. While production of such parts, the dimensions of components play a major role. The impeller assembly should have a dimension such that the electric pump is able to meet the required flow specification. Due to several different parts, it becomes difficult to achieve the compactness which affects the efficiency of the pump.

US20120121448A1, discloses an electric pump for a vehicle is disclosed. An electric pump for a vehicle, which is disclosed, may include a pump body that is divided into a motor room and a pump room, a shaft that is connected to the motor room and the pump room and a sealing unit is interposed there between, and an impeller that is mounted on the shaft in the pump room. More specifically, a leachate exhaust passage for exhausting leachate that is leaked through the sealing unit is formed in the pump body, and the leachate exhaust passage is connected to a reaction gas exhaust portion of a fuel cell stack to aide in the exhaust of the leachate accordingly. But this invention does not provide improved impeller assembly that provides compactness, and reduced diameter at the bottom end that consequently reduces input torque to maintain the flow specification and has an improved overall pump efficiency.

Therefore, there is a need of an electric water pump that along with meeting the flow specification, should be compact and has an improved efficiency and performance.

OBJECT OF THE INVENTION

The main object of the present invention is to provide an electric water pump with an improved impeller assembly that provides compactness, requires less input torque to maintain the flow specification and has an improved overall pump efficiency.

Another object of the present invention is to provide an improved impeller assembly of an electric water pump which has a reduced diameter at the bottom end that consequently reduces the input torque required to maintain flow specification.

Yet another object of the present invention is to provide an improved impeller assembly which is welded at the top end to a shroud member.

Yet another object of the present invention is to provide an improved impeller assembly which has an overmolded magnet assembled at the bottom portion of its outer surface.

Still another object of the present invention is to provide a highly efficient and affordable electric pump which is compact and easy to manufacture. SUMMARY OF THE INVENTION

The present invention provides an efficient electric water pump with an improved impeller assembly which is compact, requires less input torque to maintain the flow specification and has an improved overall pump efficiency. The electric water pump is compact and easy to manufacture.

In an embodiment, the present invention provides an improved electric water pump comprising of a volute casing, at least one washer, a rotor assembly, a rotor casing, a stator assembly, a housing subassembly, at least one PCB assembly, a self-tapping screw, a cover, and at least one mounting assembly. The impeller assembly has an over molded magnet at the bottom portion of its outer surface. Also, said impeller assembly at the top end is welded to the shroud member and has a reduced diameter at the bottom. The reduced diameter at the bottom of impeller assembly helps in reducing the input torque required to maintain the flow specification. The improved rotor assembly provides compactness, requires less input torque to maintain the flow specification and has an improved overall pump efficiency.

BRIEF DESCRIPTION OF THE DRAWINGS

An understanding of the device may be understood in more details and more particularly description of the invention briefly summarized above by reference to certain embodiments thereof which are illustrated in the appended drawings. The present invention may be obtained by reference to the following drawings:

Fig. 1 shows a sectional view of electric water pump in accordance with prior art.

Fig. 2 shows an exploded view of electric water pump with improved impeller assembly in accordance with an embodiment of the present invention.

Fig. 3 shows a sectional view of electric water pump with improved impeller assembly in accordance with an embodiment of the present invention.

Fig. 4 shows the improved impeller assembly with overmolded magnet in accordance with an embodiment of the present invention. Fig. 5 shows a plot comparing the input torque in a conventional electric water pump and the present invention.

Fig. 6 shows a plot comparing the efficiency in a conventional electric water pump and the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Many aspects of the invention can be better understood with references made to the drawings below. The components in the drawings are not necessarily drawn to scale. Instead, emphasis is placed upon clearly illustrating the components of the present invention. Moreover, like reference numerals designate corresponding parts through the several views in the drawings. Before explaining at least one embodiment of the invention, it is to be understood that the embodiments of the invention are not limited in their application to the details of construction and to the arrangement of the components set forth in the following description or illustrated in the drawings. The embodiments of the invention are capable of being practiced and carried out in various ways. In addition, the phraseology and terminology employed herein are for the purpose of description and should not be regarded as limiting.

The present invention provides an efficient and high performing electric water pump with an improved rotor assembly which is compact and requires less input torque to maintain the flow specification. The improved impeller assembly has a reduced diameter at the bottom end and an over molded magnet at the outer surface of the bottom portion. At the top end said impeller assembly is welded to the shroud member using a welding technique.

In an embodiment, the present invention provides an improved electric water pump comprising of a volute casing, at least one washer, a rotor assembly, a rotor casing, a stator assembly, a housing subassembly, at least one PCB assembly, a self-tapping screw, a cover, and at least one mounting assembly. The rotor assembly comprises of an impeller assembly and a shroud member assembled together using a welding technique. The impeller assembly has a reduced diameter at the bottom end of the improved impeller assembly which helps in reducing the input torque required to maintain the flow specification. The improved rotor assembly provides compactness, requires less input torque to maintain the flow specification and has an improved overall pump efficiency.

Referring to Fig. 1, the sectional view of a conventional electric water pump in accordance with the prior art. The electric pump 10 has a rotor assembly comprising of an impeller assembly 11 and a shroud member 12. The diameter of the impeller assembly 11 at the bottom is more than half of the thickness of the magnet 13. The electric water pump 10 requires a large input torque to maintain the flow specification.

Referring to Figs. 2 and 3, the exploded view and side view of the electric water pump with improved rotor assembly in accordance with the present invention is shown respectively. The electric water pump 20 with improved rotor assembly 24 comprising of a volute casing 21 at the top end and a cover 22 at the bottom, a washer 23; a rotor assembly 24, a rotor casing 25, a stator assembly 26, a housing sub-assembly 27, at least one PCB assembly 28, at least one self-tapping screw 29 and at least one mounting assembly 30. The rotor assembly 24 gets inserted into the rotor casing 25 with the stator assembly 26 surrounding the outer of the rotor casing 25. The self-tapping screw 29 ensures that the PCB assembly 28 is at place. In the rotor casing 25, there is a shaft 33 in the centre and an inner bush 34. The improved impeller assembly 31 at the top end is welded to the shroud member 32 through a welding technique. At the bottom end, the improved impeller assembly 31 has a reduced diameter which helps in reducing the input torque required to maintain the flow specification. Also, at the bottom portion of the impeller assembly 31, there is an over molded magnet 35. The improved rotor assembly provides compactness and ease of manufacturing.

Fig. 4 shows the improved impeller assembly in accordance with an embodiment of the present invention. In the improved impeller assembly 31 and a shroud member 32 are assembled together through a welding technique including but not limited to TIG welding, laser welding etc. The diameter at the bottom end of the improved impeller assembly 31 is reduced and at the outer surface of the bottom portion there is an overmolded magnet 35.

Fig. 5 shows a plot comparing the input torque in a conventional electric water pump and the present invention. A conventional electric water pump is compared with the improved electric water pump having an improved impeller assembly having reduced diameter at the bottom end for the input torque required to maintain the flow specification. The input torque was found to be reduced by 2% in the present invention compared to the conventional electric pump.

Fig. 6 shows a plot comparing the efficiency in a conventional electric water pump and the present invention. The compactness achieved in the present invention and reduced diameter of the impeller assembly help in increasing the overall pump efficiency. It was found that, the improved electric water pump showed approximately 2% increase in efficiency compared to a conventional electric water pump.

Therefore, the present invention provides an electric pump with improved rotor assembly that meets the flow specification, has a high overall pump efficiency and overcomes the drawbacks of the conventional electrical pump such as large input torque requirement.

The foregoing description of embodiments of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed, and modifications and variations are possible in light of the above teachings or may be acquired from practice of the invention. The embodiments were chosen and described in order to explain the principals of the invention and its practical application to enable one skilled in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated.