FIELD OF THE INVENTION

The present invention relates to the field of water pumping devices. More particularly, the present invention relates to an electric water pump with an improved magnet shape having grooves optionally combined with protrusions that allow a volume flow rate on demand for applications like cabin heating, low pressure, battery and inverter cooling due to reduction in weight of the magnet.

BACKGROUND OF THE INVENTION

A pump is a mechanical device used for moving fluids, slurries or gases from one place to another generally by converting electrical energy into hydraulic energy. Various kinds of pumps are available in the public domain according to their usage, additionally the pumps are classified according to the methodology such as direct lift, displacement and gravity pump. These pumps have wide range of application from pumping water to water cooling.

Water pumps are of one of the common type of pumps used in homes, fields, agriculture for displacing water. Some miscellaneous types of water pumps are also present in the market such as solar water pump, electric water pump and engine water pump. The working principle of the water pumps majorly depends on positive displacement principle and kinetic energy. Both AC, DC power source-based water pumps are present in state of the art.

The working of electric water pump is classified into two types i.e. centrifugal pumps and positive displacement pumps. The centrifugal pumps are operated by the help of an impeller that rotates fast and produces centrifugal force that forces the water and directs the flow of water. This kind of water pump faced many disadvantages such as less suction power, need of periodic maintenance due to presence of brushes in the DC motor, loss of torque, losses in brushes also the electric water pumps generally aren't as powerful as mechanical water pumps because of their low-flow rates. For instance, the current electric water pumps do not have ability to displace fluid like water as quickly as the mechanical counterpart.

In recent times, several electric water pumps based on volute are available, that have a curved funnel for increasing area, where the casing is responsible for receiving the fluid (i.e., water) being pumped by the impeller to ensure stable velocity of the fluid. Additionally, rotor assembly is also being introduced in the water pumps, but still some issues arise due to the circular shape of the magnet present in the rotor assembly like high cogging torque that is responsible for production of unwanted noise along with vibration predominantly at slower rotational speeds. The magnet used in the rotor assembly is polar anisotropic magnet made up of resin and rotor is made in ring form where north poles and south poles appear alternately at outer diameter due to which the conventional water pumps faced the aforementioned drawbacks.

WO2015027965A1 describes about a cooling water pump with a floating impeller for a motor vehicle, comprising a support, wherein a stator, a water pump cover, a socket injection molding, a controller and a rear cover are mounted on the support separately by bolts. A rotor impeller injection molding is mounted at the center of the stator. The rotor impeller injection molding is of a design integrating a water pump impeller with an electric machine rotor. The electric machine rotor principally comprises of permanent magnets where north poles and south poles appear alternately at outer diameter which lowers the efficiency of the water pump.

US20110254410A1 teaches about an electric water pump, a Hall IC can be mounted on a circuit substrate at an optimum position in a stable and durable state. The electric water pump includes a motor housing, a stator constituted by a stator core covered by a resin insulator and a coil, a circuit substrate, a holder mounted on the circuit substrate, and a Hall IC mounted on the holder. Electric power is supplied sequentially to the coil of the stator in order to rotate the inner magnet smoothly and continuously. The inner magnet has a circular shape due to which there is decrease in the magnetic performance of the water pump.

CN202579212U describes about electric water pump which comprises a pump body and a motor. The pump body comprises a pump casing and an impeller arranged in the pump casing, a pumping opening and a draining opening arranged on the pump casing, the motor is a direct-current brushless motor, and a motor shaft extends into the pump casing to be connected with the impeller and the motor shaft rear end is stretched out outside the rear end cover and in its periphery and is set with magnet ring. The magnet ring used therein does not increase the magnetic performance.

Due to aforementioned drawbacks, there is a need of a brushless DC (BLDC) motorbased water pumps for automotive industries which due to exclusion of the brush/commutator assembly results in decrease in audible noise and radio-frequency interference problems along with reduced weight of the magnet and enhanced magnetic performance.

OBJECT OF THE INVENTION

The main object of the present invention is to provide an electric water pump with a polar anisotropic magnet that allows a volume flow rate in accordance with the requirement.

Another object of the present invention is to provide an electric water pump that has a magnet of reduced weight for enhancing the magnetic performance.

Yet another object of the present invention is to provide an electric water pump with an improved shape of magnet having grooves optionally combined with alternate protrusions that help in ameliorating the efficiency of the water pump.

Yet another object of the present invention is to provide an electric water pump with an improved design of magnet having a comparatively greater ratio of thickness of magnet at magnet pole to thickness of magnet at the center of two consecutive poles.

Still another object of the present invention is to provide an electric water pump in which number of poles is equal to the number of grooves of the magnet so that the magnetic strength increases in the water pump that improves the time required for displacing water.

SUMMARY OF THE INVENTION The present invention relates to an electric water pump with improved shape of magnet. More particularly, the improved shape of magnet has plurality of grooves combined with in which ratio of thickness of magnet at magnet pole to thickness of magnet at the center of two consecutive poles is comparatively greater which not only results in reduction of weight of magnet but ameliorates the efficiency of the water pump.

In an embodiment, the present invention provides an electric water pump with an improved magnet shape for allowing a volume flow rate according to the requirements comprising of a hollow cover, a printed circuit board assembly, a housing sub-assembly, a stator assembly, a rotor assembly with magnet and a volute casing, wherein the printed circuit board assembly is attached in the hollow cover with the help of a self-tapping screw and the magnet has plurality of grooves optionally combined with alternate protrusions at its inner surface which helps in maximizing the magnetic strength. Also, ratio of thickness of magnet at magnet pole to thickness of magnet at the center of two consecutive poles is comparatively greater than the ratio in conventional design that leads to reduction in weight of the magnet and increases the efficiency of the water pump. The improved magnet shape also helps in achieving minimized detent torque.

In another embodiment, of the present invention, an electric water pump with an improved magnet design comprising of a rotor casing with a shaft to join the stator assembly and rotor assembly, plurality of mounting assembly provided at the sides of housing sub-assembly. The applications of magnetic water pump are found in cabin heating, low pressure battery and inverter cooling as well as cooling of turbocharged air for passenger cars, light duty or medium duty vehicles.

The above objects and advantages of the present invention will become apparent from the hereinafter set forth brief description of the drawings, detailed description of the invention, and claims appended herewith.

BRIEF DESCRIPTION OF THE DRAWING

The present invention will be described with reference to the following drawings. The drawings and the associated descriptions are provided to illustrate embodiments of the invention and not to limit the scope of the invention. Fig. 1 shows a front view of an electric water pump.

Fig. 2 shows a cross-sectional view of an electric water pump.

Fig. 3 shows an exploded view of an electric water pump.

Fig. 4 shows a top view of conventional magnet design with no grooves.

Fig. 5a and Fig. 5b show top views of an improved magnet shape.

Fig. 6a and Fig. 6b show top views of another improved magnet shape.

Figs. 7a to 7d are comparison graphs for conventional magnet shape with both improved magnet shapes.

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 relates to an electric water pump with an improved magnet design for cabin heating, low pressure, battery and inverter cooling as well as cooling of turbocharged air for passenger cars, light duty or medium duty vehicles having an improved design of the magnet i.e., lighter in weight and effective than the conventional water pumps. In an embodiment, the present invention provides an electric water pump (14) with an improved magnet shape for allowing a volume flow rate according to the requirements comprising of a hollow cover (3), a printed circuit board assembly (8), a housing subassembly (2), a stator assembly (11), a rotor assembly (6) with magnet (7, 15) and a volute casing (1), and a washer (9) attached between the volute casing (1) and rotor assembly (6), wherein the printed circuit board assembly (8) is attached in the hollow cover (3) with the help of a self-tapping screw (10) and the magnet (7, 15) has plurality of grooves optionally combined with alternate protrusions at the inner surface that helps in maximizing the magnetic strength. Also in the magnet (7, 15), the ratio of thickness of magnet (7, 15) at magnet pole to thickness of magnet (7, 15) at the center of two consecutive poles is comparatively greater than conventional design that leads to reduction in weight of the magnet (7, 15) but increase the efficiency of the water pump. The improved magnet shape also helps in achieving minimized detent torque.

In another embodiment, of the present invention an electric water pump (14) with an improved magnet shape comprising of a rotor casing (4) with a shaft (12) to join the stator assembly (11) and rotor assembly (6), plurality of mounting assembly (5) provided on the sides of housing sub-assembly (2).

Fig. 1 depicts a front view of an electric water pump (14) with an improved magnet comprising of a cover (3) at the lower most region. The housing sub-assembly (2) is placed between the cover (3) and the volute casing (1). The mounting assemblies are assembled on left and right comer of the housing sub-assembly (2).

Fig. 2 depicts a cross-sectional view of an electric water pump (14) with an improved magnet shape that comprises a printed circuit board assembly (8) having one or more microprocessors and data storage unit is assembled in the hollow cover (3) with the help of a self-tapping screw in order to adjust the operations of the water pump (14), over which the rotor casing is present in the housing sub-assembly (2) along with the rotor assembly (6) and magnet (7, 15). For instance, the printed circuit board (8) receives the command signal and sends to that command to a data bus signal for actuation of the water pump (14) and visa- versa. Moreover, the user may also control the flow with the help of printed circuit board (8). Fig. 3 represents an exploded view of an electric water pump (14) with an improved magnet shape comprising of the hollow cover (3), printed circuit board assembly (8), housing sub-assembly (2), stator assembly (11), rotor assembly (6) with the magnet (7, 15) and volute casing (1), wherein the printed circuit board assembly (8) is attached in the hollow cover (3) with the help of a self-tapping screw. The rotor casing (4) with a shaft (12) is there to join the stator assembly (11) and rotor assembly (6), plurality of mounting assembly provided on the sides of housing sub-assembly (2).

The role of the volute casing (1) is to receive the fluid (i.e. water) being pumped by the rotor while maintaining the velocity of the fluid as the fluid has high kinetic energy and the volute casing (1) directs this flow through to the discharge. The rotor assembly (6) rotates due to the interaction between the windings and magnetic fields in the magnet (7, 15) which produces a torque around the rotor's axis. Furthermore, the stator assembly (11) provides a rotating magnetic field that drives the rotor and converts the rotating magnetic field to electric current along with this the stator assembly (11) is also responsible for guiding the flow of fluid to or from the rotor assembly (6).

Fig. 4 depicts a top view of conventional magnet (13) design with no grooves. The conventional magnet (13) is polar anisotropic magnet made up of resin and rotor is made in ring form where north poles and south poles appear alternately at outer diameter due to which issues such as high cogging torque that is responsible for production of unwanted noise along with vibration predominantly at slower rotational speeds arises.

Fig. 5a and Fig. 5b show a top view of an improved magnet shape having multiple grooves on the inner surface, wherein the grooves (16) help in achieving maximum magnetic strength at grooves (16) as shown by red arrows in Fig. 5a and achieve a comparatively greater ratio of thickness (A) of magnet (7) at magnet pole to thickness (B) of magnet at the center of two consecutive poles than the conventional designs i.e. greater than 0.95, the ratio of distance (C) between the center of magnet (7) to the outer edge mid of two consecutive magnet pole to the radius (D) of magnet (7) is less than 1.025 as shown in Fig. 5b that leads to reduction in weight of the magnet (7) but increase the efficiency of the water pump (14). Fig. 6a and Fig. 6b show a top view of an improved magnet shape having multiple grooves and alternate protrusions (17) on the inner surface, wherein the grooves (16) help in achieving maximum magnetic strength at grooves (16) as shown by red arrows in Fig. 6a and achieve a comparatively greater ratio of thickness (A) of magnet (15) at magnet pole to thickness (B) of magnet at the center of two consecutive poles than the conventional designs i.e. greater than 0.95, the ratio of distance (C) between the center of magnet (15) to the outer edge mid of two consecutive magnet pole to the radius (D) of magnet (15) is less than 1.025 as shown in Fig. 6b that leads to reduction in weight of the magnet (15) but increase the efficiency of the water pump (14).

The electric water pump (14) that is based on brushless DC (BLDC) motor and has application in automotive industries. Due to exclusion of the brush/commutator assembly and introduction of grooves on the magnet of rotor assembly, the present invention has resulted in decrease in audible noise and radio-frequency interference problems and has application in cabin heating, low pressure battery and inverter cooling as well as cooling of turbocharged air for passenger cars, light duty or medium duty vehicles.

EXAMPLE 1

COMPARATIVE ANALYSIS

A DC power supply is given as input to the electric water pump (14) with an improved magnet shape and the conventional magnet (13) design with no grooves for a comparative analysis. Due to the grooves in the improved magnet shape, the weight of the conventional magnet in the rotor assembly (6) is more compared to the improved magnet (7) referred as shape 1 and improved magnet (15) referred as shape 2 as shown in Fig. 7a, surface gauss of the conventional design i.e. circular magnet is maximum, whereas the improved magnet (7, 15) has less surface gauss as shown in Fig. 7b. The amount of detent torque (i.e. the measured ability of rotor assembly (6), as of the shaft (12), to overcome turning resistance), that must be applied to overcome the static equilibrium of the motor when it is in the state of rest and unpowered is maximum in conventional design and has reduced significantly in the improved magnet shape i.e. the improved magnet (7, 15) achieve low consumption of energy as shown in Fig. 7c. The air gap lux density in the conventional design is more and the improved magnet (7, 15) has achieved less air gap flux density that is related to flux fringing and flux leakage as shown in Fig. 7d. Moreover, due to the grooves in improved magnet (7, 15) in present invention, the magnetic strength increases with reduction in weight.

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.