ASSEMBLY”

FIELD OF THE INVENTION The present invention relates to an electric water pump with an improved rotor assembly. More particularly, the present invention relates to an improved rotor 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 with minimized pump losses.

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 HEV or 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 such as impeller assembly, shroud etc. are manufactured and then assembled together. While production of such parts the dimensions of components play a major role. Due to several different parts, the compactness is compromised and there is possibility of losses and these factors contribute in affecting the overall efficiency of the pump.

US4746270A, discloses an engine water pump assembly is formed of a rotatable shaft divided along its length into a bearing portion terminating in a drive connection and a sealing portion terminating in an impeller end upon which a water impeller is mounted. A tubular, journal-type bearing surrounds the shaft bearing portion. A pump housing surrounds the shaft and bearing and has an integral, enlarged chamber formed on one end within which the impeller is located. The opposite end of the housing has an opening through which the shaft drive connection extends. The bearing has an integral, annular flange which surrounds a part of the shaft sealing portion. A seal mounted upon the shaft sealing portion seals against the flange to prevent the flow of water from the impeller chamber to the bearing part of the housing and its opening. The housing is molded around the bearing to form an integral subassembly. The shaft and seal may be pre-assembled and then inserted, as a subassembly, through the housing chamber towards and into the bearing and its flange. But this invention does not provide compactness, and neither proposes a solution to reduce input torque to maintain the flow specification and minimize pump losses.

Therefore, there is a need of an electric water pump that along with meeting the flow specification, should be compact, has minimum pump losses, 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 rotor assembly that provides compactness, requires less input torque to maintain the flow specification and has an improved overall pump efficiency with minimized pump losses.

Another object of the present invention is to provide an improved rotor assembly with an improved impeller assembly of an electric water pump which has an outer diameter lesser than the outer diameter of the shroud member that consequently reduces the input torque required to maintain flow specification. Yet another object of the present invention is to provide an improved rotor assembly which comprises an improved impeller assembly and a shroud member assembled together using a welding technique including but not limited to CIT- clean infrared welding technology, UW - ultrasonic welding, laser welding etc.

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 rotor assembly comprising of an improved impeller assembly and a shroud member that provides compactness, requires less input torque to maintain the flow specification and has an improved overall pump efficiency with minimized pump losses. 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 rotor assembly comprises of an impeller assembly and a shroud member assembled together using a welding technique. The impeller assembly has an outer diameter less than the outer diameter of the shroud member 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 with minimized pump losses.

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 rotor assembly in accordance with an embodiment of the present invention.

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

Fig. 4 shows the improved rotor assembly with improved impeller assembly 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.

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 rotor assembly comprises of an improved impeller assembly wherein the outer diameter of the impeller assembly is less than the outer diameter of shroud member and said impeller assembly is assembled with a 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 an outer diameter less than the outer diameter of the shroud member 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 with minimized pump losses.

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 outer diameter of the impeller assembly 11 is equal to the outer diameter of the shroud member 12. 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 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 rotor assembly 24 comprises of an improved impeller assembly 31 and a shroud member 32 assembled together through a welding technique and the outer diameter of the improved impeller assembly 31 is made lesser than the outer diameter of the shroud member 32 which helps in reducing the input torque required to maintain the flow specification. The improved rotor assembly provides compactness and ease of manufacturing.

Fig. 4 shows the improved rotor assembly with improved impeller assembly in accordance with an embodiment of the present invention. In the rotor assembly 24, the improved impeller assembly 31 and a shroud member 32 are assembled together through a welding technique including but not limited to ultrasonic welding, TIG welding, laser welding etc. The outer diameter of the improved impeller assembly 31 is made lesser than the outer diameter of the shroud member 32.

Fig. 5 shows a plot comparing the input torque in a conventional electric water pump and the present invention. The conventional electric water pump is compared on the criteria of input torque required to maintain the flow specification with the improved electric water pump having an improved impeller assembly welded to shroud member and having an outer diameter less than the outer diameter if the shroud member. The input torque was found to be reduced by 2% in the present invention compared to the conventional electric 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 and pump losses.

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.