WO2021191841A1

WO2021191841A1 - Electric water pump with improved bush

Info

Publication number: WO2021191841A1
Application number: PCT/IB2021/052491
Authority: WO
Inventors: Kabir BHANDARI; Amardip KUMAR; Praveen Gupta; Ashok Kumar
Original assignee: Padmini Vna Mechatronics Pvt. Ltd.
Priority date: 2020-03-25
Filing date: 2021-03-25
Publication date: 2021-09-30

Abstract

The present invention relates to an electric water pump with improved bush, comprising of, a volute casing (1), a housing (3), wherein, the housing (3) accommodates a rotor assembly (4) that is associated with a cylindrical bush (12), a rotor (5) with a rotor casing (6) for holding a shaft (7), the shaft is a symmetrical hex shaped shaft (7) with at least two grooves located on both the shaft (7) ends and inserted in the rotor casing (6), the cylindrical bush (12) has grooves (13) is capable of balancing the pressure between an impeller and bottom of the rotor assembly (4) and simultaneously allowing flow of a coolant through the grooves (13) present on the cylindrical bush (12) that carry away dirt and /or foreign particle(s) and wear the particle(s) from the electric water pump, thereby maintaining efficiency of the electric water pump.

Description

“ELECTRIC WATER PUMP WITH IMPROVED BUSH”

FIELD OF THE INVENTION

The present invention relates to an electric water pump with improved bush. More particularly, the present invention is directed towards an electrically controlled BLDC motor based electric water pump equipped with a bush having grooves on its surface for providing balancing of pressure in a pump and having applications in cabin heating, cooling of engine, inverter and battery in electric/hybrid vehicles.

BACKGROUND OF THE INVENTION

Conventionally, water pumps are 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. The rotational speed of internal combustion engine is responsible for determining the amount of refrigerant flowing out of the mechanical water pump. Therefore, in order to operate the heater and the radiator normally, the engine speed must be increased. Thus, on increasing the engine speed the fuel consumption also increases.

At present, in contrast with the mechanical water pump, the large number of vehicles are shifted towards an electric water pump as the electric water pump is capable of determining the amount of refrigerant regardless of the rotational speed of the internal combustion engine. The electric water pump is driven by an electric motor and is controlled by a controlling unit. The electrically driven water pump employed in the electric /hybrid vehicles is used for the cooling of its components. During the circulation of water in electric pump, there exist a pressure gradient between impeller and bottom of the rotor assembly which has a negative effect on flow rate of the pump.

CN205478500U discloses an electric water pump includes the pump seat, locate the motor on the pump seat, the pump body that links to each other with the motor, the pump body includes the pump chamber, locates the lifting pipe of the pump chamber left and right sides, the pump body all adopts plastic materials to make, be equipped with on the lifting pipe and be used for the connecting pipe that meets with the pump chamber, be equipped with the double -screw bolt along its length direction on the outer circumference of connecting pipe, the orifical double -screw bolt that is close to the lifting pipe extend to the lifting pipe orientation and with the lifting pipe link as an organic whole, lifting pipe and connecting pipe are all made with double -screw bolt an organic whole, and the fix with screw of lifting pipe through passing the double -screw bolt is on the pump chamber. Although the cited invention provides the electrically operated water pump for circulating pressurized water from inlet to outlet, but it does not provide any means to reduce the pressure gradient and the design is much complicated.

Therefore, in order to overcome the aforementioned drawback, there exists a need to develop highly reliable and efficient electric water pump for balancing the pressure between impeller and bottom of rotor casing assembly and simultaneously allowing coolant to circulate from grooves surface to carry away foreign particle and wear particle.

OBJECT OF THE INVENTION The main object of the present invention is to provide an electrically controlled BLDC motor based electric water pump having applications in cabin heating, low pressure EGR cooling, battery cooling, inverter cooling and alike.

Another object of the present invention is to provide an improved bush with grooves embedded in the electric pump to avoid pressure gradient between impeller and bottom of the rotor casing assembly which has a negative effect on flow rate of the pump.

Yet another object of the present invention is to circulate the coolant/water through grooves on the guiding surface to carry away foreign particle and wear particle.

Still another object of the present invention is to develop an electric water pump with improved bush that is highly reliable, efficient and cost effective.

SUMMARY OF THE INVENTION

The present invention envisioned to an electric water pump having an improved bush with grooves to avoid pressure gradient between impeller and bottom of rotor casing assembly. Moreover, the flow of coolant/water through grooves on the guiding surface allows the coolant/water to carry away foreign particle and wear particle.

In an embodiment, the present invention provides an electric pump with improved bush comprising of a volute casing; a washer; a housing with at least two mounting assembly; a rotor assembly; a cylindrical bush with grooves embedded in the rotor assembly; a rotor; a rotor casing; a shaft with at least two grooves on both the end of shaft inserted in the rotor casing; a stator assembly; a PCB; a self-tapping screw; and a cover for covering lower part of pump.

Here, the rotor casing is preferably made up of resin including but not limited to polyphenylene sulfide (PPS). The housing accommodates plurality of electric pump components such as stator assembly, rotor assembly, rotor casing, cylindrical bush and PCB and the flow of coolant/ water through grooves on the bush removes the pressure gradient which has a negative effect on flow rate of the pump and also carries away dirt/foreign particle and wear particle from the pump, thus maintaining the efficiency of the water pump.

BRIEF DESCRIPTION OF THE DRAWINGS

The object of the invention 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, which drawings form a part of this specification. It is to be noted, however, that the appended drawings illustrate preferred embodiments of the invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective equivalent embodiments.

Fig. 1 represents an exploded view of electric water pump with improved bush in accordance with an embodiment of the present invention.

Fig. 2 represents a side view of electric water pump with improved bush in accordance with an embodiment of the present invention.

Fig. 3 represents a sectional view of electric water pump with improved bush in accordance with an embodiment of the present invention. Fig. 4(a) shows a perspective view of the improved bush with grooves in accordance with an embodiment of the present invention.

Fig. 4(b) represents an exploded view of the improved bush with rotor assembly in accordance with an embodiment of the present invention. Fig. 5 shows a perspective view of the electric water pump with improved bush in accordance with an embodiment of the present invention.

Fig. 6 shows a sectional view of a conventional electric water pump in accordance with an embodiment of the present invention.

Fig. 7(a) and Fig. 7(b) presents simulation results of axial force simulation and breaking torque of the conventional electric water pump.

Fig. 8(a) and Fig. 8(b) presents simulation results of axial force simulation and breaking torque of the electric water pump with improved bush.

Fig. 9(a) and Fig. 9(b) presents comparison results of axial force simulation and breaking torque simulation of conventional electric pump and electric water pump with improved bush.

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 discloses the electric water pump having an improved cylindrical bush with grooves on its surface. Moreover, the flow of coolant/water through grooves on the bush removes the pressure gradient which develops due to low pressure at the impeller and high pressure at the bottom of the rotor assembly and also carry away the foreign/ dirt particle and wear particle from the pump in order to maintain the efficiency of the electric water pump.

In an embodiment referring to Fig. 1 and Fig. 2, the exploded and side view of electric water pump with improved bush is illustrated. Said electric water pump with improved bush comprises of a volute casing 1; a washer 2; a housing 3; a mounting assembly 3a; a rotor assembly 4; a rotor 5; a rotor casing 6; a symmetrical hex shaped shaft 7 with at least two grooves located on both the shaft ends; a stator assembly 8; a PCB 9; a self tapping screw 10; and a cover 11. The side view of the electric water pump comprising a volute casing 1; a housing 3 with at least two mounting assembly 3a and 3b and a cover 11 is depicted in Fig. 2.

Now referring to Fig. 3, a sectional view of the electric water pump with improved bush is illustrated. A volute casing 1 is mounted over a rotor casing 6 of the pump. A rotor assembly 4 is fitted inside the volute casing 1. Below the rotor assembly 4, a rotor 5 is placed. The rotor 5 is fitted inside the rotor casing 6 fitted with a shaft 7. Between the shaft 7 and rotor 5, a cylindrical bush 12 with grooves is provided that helps in removing the pressure gradient which develops due to low pressure at the impeller and high pressure at the bottom of the rotor assembly 4. A washer 2 is placed between the volute casing 1 and bush 12. The housing 3 accommodates the rotor assembly 4, cylindrical bush 12, rotor 5 with rotor casing 6 for holding a symmetrical hex shaped shaft 7. A PCB 9 is placed below the housing fitted using a self-tapping screw and a cover 11 for covering lower part of electric pump.

Now referring to Fig. 4(a), an improved bush 12 with grooves 13 on its surface is illustrated and Fig. 4(b) represents exploded view of bush 12 with rotor assembly 4. The cylindrical bush 12 is placed inside the rotor assembly 4 and outside of shaft 7 and the rotor 5 is arranged outside of the bush 12 to rotate integrally with the bearing part. The improved bush 12 with grooves 13 is capable of balancing the pressure between impeller and bottom of the rotor assembly 4 by allowing the flow of coolant/ water through the grooves 13 present on the bush 12 and also carry away dirt/foreign particle and wear particles from the pump.

Now referring to Fig. 5, a perspective view of the electric water pump with improved bush is illustrated in which the shaft (7) has a symmetrical hex shaped shaft (7) with at least two grooves located on both the shaft (7) ends and inserted in the rotor casing (6). A sectional view of a conventional electric water pump is illustrated with a conventional shaft member (7’) in Fig. 6 in which an axial force simulation and breaking torque simulation results are presented in Fig. 7(a) and Fig. 7(b). Now referring to Fig. 8(a) and Fig. 8(b) axial force simulation and breaking torque simulation results of the electric water pump with improved bush and symmetrical hex shaped shaft ( 11) is illustrated.

The comparison results of axial force simulation and breaking torque simulation of conventional electric pump and electric water pump with improved bush are presented in Fig. 9(a) and Fig. 9(b) from which, it is observed that the breaking torque and axial force both are greater than the conventional electric water pump. The present invention provides a highly efficient and affordable electrically controlled BTDC motor based electric water pump with improved bush having applications in cooling of engine, power electronics inverter and battery in electric/hybrid vehicles. During the operation of electric water pump, a pressure gradient is developed due to the low pressure at the impeller and high pressure at the bottom of the rotor assembly and causes a negative effect on flow rate of the water pump. Therefore, in order to avoid such pressure gradient, the electric pump is equipped with an improved bush having grooves on its surface.

The coolant/water flows through the grooves present on the bush and removes the pressure gradient which develops between the impeller and bottom of the rotor assembly. Sometimes, with the circulation of coolant/water in the electric water pump, the contaminated or foreign particle along with the wear particles are also introduced in the pump. Hence from improved bush, such foreign particle and wear particle gets carried away by circulating water through the grooves of bush in order to maintain the reliability and efficiency of the water pump. 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.

Claims

CLAIMS We claim:

1. An electric water pump with improved bush, comprising of: a volute casing (1); a washer (2); a housing (3) with at least two mounting assembly (3a) and (3b); a cover (11) for covering a lower part of the electric water pump; wherein, the housing (3) accommodates a rotor assembly (4) connected with a cylindrical bush (12), a rotor (5) with a rotor casing (6) for holding a shaft (7); the shaft is a symmetrical hex shaped shaft (7) with at least two grooves located on both the shaft (7) ends and inserted in the rotor casing (6); the cylindrical bush (12) has grooves (13) for balancing pressure between the impeller/ rotor (5) and bottom of the rotor assembly (4) and simultaneously allowing flow of a coolant through the grooves (13) present on the cylindrical bush (12) that carry away dirt and/ or foreign particle(s) and wear particle(s) from the electric water pump, thereby maintaining efficiency of the electric water pump.

2. The electric water pump with improved bush as claimed in Claim 1, wherein said rotor casing (6) is preferably made up of resin including but not limited to polyphenylene sulfide (PPS).

3. The electric water pump with improved bush as claimed in Claim 1, wherein said electric water pump with improved bush has a PCB (9) that is placed below the housing (3) fitted using a self-tapping screw (10).

4. The electric water pump with improved bush as claimed in Claim 1, wherein said cylindrical bush (12) is preferably placed inside the rotor assembly (4) and outside of the shaft (7) and the rotor (5) is arranged outside of the cylindrical bush (12) to rotate integrally with a bearing part.

5. The electric water pump with improved bush as claimed in Claim 1, wherein said cylindrical bush (12) with grooves (13) helps in removing a pressure gradient that develops due to low pressure at the impeller and high pressure at the bottom of the rotor assembly (4).

6. The electric water pump with improved bush as claimed in Claim 1, wherein said washer (2) is placed between the volute casing (1) and bush (12).

7. The electric water pump with improved bush as claimed in Claim 1, wherein said coolant includes but not limited to water, ethylene glycol, diethylene glycol.