Patent Publication Number: US-2022220962-A1

Title: Electric water pump

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a National Stage application of international application No. PCT/CN2020/102011 filed on Jul. 15, 2020, titled “ELECTRIC WATER PUMP”, in the China National Intellectual Property Administration, the content of which is hereby incorporated by reference. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates to the field of flow rate control, and in particular, to an electric water pump. 
     BACKGROUND 
     Electric water pumps are widely used in new energy vehicles such as electric vehicles and hybrid electric vehicles, and is an important component of automotive thermal management systems. Electric water pumps are mainly used to cool components such as engines, turbochargers, batteries, motors, and controllers. In the electric water pump, a rotor assembly is an important component of the electric water pump, which affects the motor efficiency of the electric water pump. In addition, a structure and material of the rotor assembly directly affect the performance and cost of the electric water pump. 
       FIG. 1  shows a conventional electric water pump, including a magnetic ring  1 , a graphite bearing  2 , an impeller cover  3  and an injection molding adapting piece  4  configured for connecting the magnetic ring  1  and the graphite bearing  2 . A magnetic performance of the magnetic ring  1  is an important factor affecting the rotor assembly. The conventional magnetic ring  1  is made of neodymium-iron-boron material directly by a process of molding injection, and a large amount of neodymium-iron-boron material is consumed, which results in a higher total cost of the rotor assembly. The graphite bearing  2  has a high wear resistance, which can protect the rotor assembly from wearing at high speed. However, since the graphite bearing  2  has a high wear resistance, it is difficulty to process and the cost is relatively high. Therefore, the overall cost of the electric water pump using the conventional rotor assembly is high. Moreover, the connection between the magnetic ring  1  and the injection molding adapting piece  4  of the conventional rotor assembly is easily disconnected, so that the magnetic ring  1  rotates, but the impeller cover disposed on the injection molding adapting piece  4  cannot be driven to rotate, making the whole rotor assembly ineffective. 
     SUMMARY 
     On the basis of embodiments of the present disclosure, an electric water pump is provided. 
     An electric water pump includes a pump housing, a stator assembly and a rotor assembly. The stator assembly is disposed in the pump housing and the rotor assembly matches with the stator assembly. The rotor assembly includes an iron core body, a first plastic coating layer, a second plastic coating layer and a plurality of magnetic sheets, wherein the iron core body is provided with a central through-hole. The plurality of magnetic sheets are disposed in the iron core body, the first plastic coating layer and the second plastic coating layer are configured for enclosing the iron core body. At least one protruding rib is disposed on a top surface, a bottom surface, or both a top surface and a bottom surface of the first plastic coating layer, and at least one recess matching with the at least one protruding rib is disposed on the second plastic coating layer. The first plastic coating layer is able to drive the second plastic coating layer to rotate relative to an axis of the central through-hole of the iron body by cooperation between the at least one protruding rib and the at least one recess. 
     In an electric water pump of the present disclosure, the magnetic sheet is disposed in the iron core body, and the first plastic coating layer is used to replace the conventional magnetic ring, so as to reduce consumption of the magnetic sheet, thereby reducing the cost. At the same time, the second plastic coating layer is used to replace the graphite bearing, which can further reduce the cost of the rotor assembly, thereby reducing the whole cost of an electric water pump using the rotor assembly in the present disclosure. At the same time, the at least one protruding ribs disposed on the first plastic coating layer can improve connection strength between the second plastic coating layer and the first plastic coating layer. Therefore, when the rotor assembly is assembled on the electric water pump and rotate at a high speed, the first plastic coating layer and the second plastic coating layer will not separate from each other, thereby improving reliability of the rotor assembly during use. 
     In some embodiments, a plurality of protruding ribs are disposed on at least one of the top surface and/or the bottom surface of the first plastic coating layer. Therefore, connection strength between the first plastic coating layer and the second plastic coating layer can be further strengthened. 
     In some embodiments, four protruding ribs are disposed on the top surface and/or the bottom surface of the first plastic coating layer, and the four protruding ribs are symmetrically disposed relative to the axis of the central through-hole of the iron core body. Therefore, the first plastic coating layer can evenly and stably drive the second plastic coating layer to rotate. 
     In some embodiments, a plurality of positioning grooves are disposed on an outer surface of the first plastic coating layer, and the plurality of positioning grooves matches with the plurality of magnetic sheets one by one, respectively. Therefore, it is convenient to locate the magnetic sheet, and to magnetize the magnetic sheet. 
     In some embodiments, each of the plurality of positioning grooves is disposed on a mid-vertical plane of corresponding one of the plurality of magnetic sheets. Therefore, a center line of the magnetic sheet can be accurately located with the positioning groove as a mark. 
     In some embodiments, a plurality of positioning holes are disposed on a bottom surface of the second plastic coating layer, and the plurality of positioning holes matches with the plurality of magnetic sheets one by one, respectively. Therefore, when the magnetic sheet needs to be magnetized, the magnetizing device can be disposed directly at the positioning hole. It is convenient to magnetize the magnetic sheet. 
     In some embodiments, the plurality of positioning holes are disposed on a center line of corresponding one of the plurality of magnetic sheets. Therefore, the magnetic sheets can be accurately located, so as to avoid influence on magnetizing caused by misplacing the magnetizing device. 
     In some embodiments, the plurality of positioning grooves extend from an edge of the first plastic coating layer to an opposite edge of the first plastic coating layer. Therefore, the magnetic sheet can be entirely located. Moreover, the plurality of positioning holes can be disposed referring to the plurality of positioning groove. 
     In some embodiments, the first plastic coating layer is disposed on the iron core body by a process of injection molding, and the second plastic coating layer is disposed on the first plastic coating layer a process of by injection molding. Therefore, a process of welding can be omitted. 
     In some embodiments, the protruding rib and the first plastic coating layer are an integral structure. Therefore, a process of welding can be omitted. 
     In some embodiments, an impeller cover is disposed on an end surface away from the iron core body of the second plastic coating layer, and the impeller cover is fixed to the second plastic coating layer by welding. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In order to better describe and explain the embodiments and/or examples of those inventions disclosed herein, one or more drawings may be referred to. The additional details or examples used to describe the drawings should not be considered as limiting the scope of any of the disclosed inventions, the currently described embodiments and/or examples, and the best mode of these inventions currently understood. 
         FIG. 1  is a cross section view of a rotor assembly in conventional art. 
         FIG. 2  is a cross section view of an electric water pump in an embodiment of the present disclosure. 
         FIG. 3  is a structural schematic diagram of a rotor assembly of the electric water pump in  FIG. 2 . 
         FIG. 4  is a structural schematic diagram of a rotor assembly of the electric water pump in  FIG. 2 . 
         FIG. 5  is an assembly schematic diagram of a first plastic coating layer, an iron core body and a magnetic sheet in  FIG. 3 . 
         FIG. 6  is a cross section view of  FIG. 5 . 
     
    
    
     IN THE DRAWINGS 
       100  represents an electric water pump;  10  represents a pump housing;  11  represents a center positioning shaft;  20  represents a stator assembly;  30  represents a rotor assembly;  31  represents an iron core body;  32  represents a magnetic sheet;  33  represents a first plastic coating layer;  331  represents a positioning groove;  34  represents a second plastic coating layer;  341  represents a positioning hole;  342  represents a recess;  35  represents an impeller cover;  301  represents a central through-hole;  302  represents a protruding rib;  1  represent a magnetic ring;  2  represents a graphite bearing,  3  represents an impeller cover; and  4  represents an injection molding adapting piece. 
     DETAILED DESCRIPTION 
     The present disclosure will be further described in detail below with reference to the drawings and specific embodiments, in order to better understand the objective, the technical solution and the advantage of the present disclosure. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of the disclosure. 
     It should be noted that when an element is referred to as being “fixed” to another element, it may be directly attached to the other element or a further element may be presented between them. When an element is considered to be “connected” to another element, it may be directly connected to the other element or connected to the other element through a further element (e.g., indirectly connected). 
     Unless otherwise defined, all technical and scientific terms used herein have the same meaning as a skilled person in the art would understand. The terminology used in the description of the present disclosure is for the purpose of describing particular embodiments and is not intended to limit the disclosure. 
     Referring to  FIG. 2  to  FIG. 6 , an embodiment of the present disclosure provides an electric water pump  100 . The electric water pump  100  can be used as a thermal management system component of an electric vehicle and a hybrid electric vehicle, and is configured to supply power for working medium in the thermal management system to circulate. In some embodiments, the electric water pump  100  can be used for transporting other working medium in other pipeline systems. 
     An electric water pump  100  includes a pump housing  10 , a stator assembly  20  and a rotor assembly  30 . The stator assembly  10  can be disposed in the pump housing  10  and a rotor assembly  30  can match with the stator assembly  20 . Wherein, a center position shaft  11  can be further disposed in the pump housing  10 . The rotor assembly  30  can be sleeved on the center positioning shaft  11  and match with the stator assembly  20 . The rotor assembly  30  can rotate relative to the center positioning shaft  11 , so that the electric water pump  100  can control flow rate during use. 
     In the present embodiment, the rotor assembly  30  can include an iron core body  31 , a first plastic coating layer  33 , a second plastic coating layer and a plurality of magnetic sheets  32 . The iron core body  31  can be provided with a central through-hole  301 . The plurality of magnetic sheets  32  can be disposed in the iron core body  31 . The first plastic coating layer  33  and the second plastic coating layer  34  can be configured for enclosing the iron core body  31 . Wherein, an impeller cover  35  can be disposed on an end surface away from the iron core body  31  of the second plastic coating layer  34 , and the impeller cover  35  can be fixed to the second plastic coating layer  34  by welding. 
     In some embodiments, the impeller cover  35  can be fixed to the second plastic coating layer  34  by ultrasonic welding. It can be understood that a product fixed by ultrasonic welding can have high strength and good tightness. 
     In some embodiments, the first plastic coating layer  33  can be disposed on the iron core body  31  by a process of injection molding, and configured for enclosing the iron core body  31 . The second plastic coating layer  34  can be disposed on the first plastic coating layer  33  a process of by injection molding. Therefore, a process of welding can be omitted, and the technological process can be simpler. 
     It can be understood that a magnetic ring  1  of the rotor assembly  30  can be collectively formed by the iron core body  31 , the plurality of magnetic sheets  32  and the first plastic coating layer  33 . In conventional art, the magnetic ring  1  is made of neodymium-iron-boron material directly by a process of molding injection, which has a high cost. Moreover, in the present embodiment, the second plastic coating layer  34  can be disposed on the first plastic coating layer  33 . That is, the second plastic coating layer  34  in the rotor assembly  30  of the present embodiment can be used to replace the graphite bearing  2  in a conventional rotor assembly. Therefore, the graphite bearing  2  can be omitted, so as to reduce the cost. It should be noted that the second plastic coating layer  34  can be made of anti-wear materials such as a combination of PPS (i.e. Phenylenesulfide) and carbon fiber, and the like. Comparing with the graphite bearing  2 , the second plastic coating layer  34  is easy to process and has a low cost. When the rotor assembly  30  is assembled on the electric water pump, the second plastic coating layer  34  can make the rotor assembly  30  to rotate relative to the center positioning shaft  11  at a high speed, and the second plastic coating layer  34  will not be damaged by contact friction between the second plastic coating layer  34  and the center positioning shaft  11 . The first plastic coating  33  can be made of heat-resisting materials such as a combination of PPS and glass fiber, nylon and the like. 
     In the present embodiment, at least one protruding rib  302  can be disposed on at least one of a top surface and a bottom surface of the first plastic coating layer  33 , and at least one recess  342  matching with the at least one protruding rib  302  can be disposed on the second plastic coating layer  34 . The first plastic coating layer  33  can be able to drive the second plastic coating layer  34  to rotate relative to an axis of the central through-hole  301  of the iron core body  31  by cooperation between the at least one protruding rib  302  and the at least one recess  342 . The first plastic coating layer  33  can make use of cooperation between the protruding rib  302  and the recess  342  to drive the second plastic coating layer  34  to rotate, thereby improving a connecting strength between the first plastic coating layer  33  and the second plastic coating layer  34 . Therefore, when the rotor assembly  30  is assembled on the electric water pump  100  and rotates at a high speed, the first plastic coating layer  33  and the second plastic coating layer  34  will not separate from each other, thereby improving reliability of the rotor assembly  30  during use. 
     The at least one protruding rib  302  can be disposed on at least one of the top surface and the bottom surface of the first plastic coating layer  33 . That is, at least one protruding rib  302  can be disposed on the top surface of the first plastic coating layer  33 , and the bottom surface of the first plastic coating layer  33  is not provided with the protruding rib  302 ; alternatively, at least one protruding rib  302  can be disposed on the bottom surface of the first plastic coating layer  33 , and the top surface of the first plastic coating layer  33  is not provided with the protruding rib  302 ; or, at least one protruding rib  302  can be disposed on both the top surface of the first plastic coating layer  33  and the bottom surface of the first coating layer  33 , thereby further improving the connecting strength between the first plastic coating layer  33  and the second plastic coating layer  34 . Thus, the protruding rib  302  and the first plastic coating layer  33  can have an integral structure. 
     In details, in the present embodiment, four protruding ribs  302  can be disposed on the top surface and/or the bottom surface of the first plastic coating layer  33 , and the four protruding ribs  302  can be symmetrically disposed relative to the axis of the central through-hole  301  of the iron core body  31 . Therefore, the first plastic coating layer  33  can evenly and stably drive the second plastic coating layer  34  to rotate. It should be noted that a number of the protruding ribs  302  on the top surface of the first plastic coating layer  33  and a number of the protruding ribs  302  on the bottom surface of the first plastic coating layer  33  is not limited to that shown in the figures. The skilled in the art can set different numbers of protruding ribs  302  on the top surface of the first plastic coating layer  33  and the bottom surface of the first plastic coating layer  33  according to actual needs. In addition, the electric water pump can include one, two, three, five, and even a plurality of protruding ribs  302 . Besides, the protruding  302  is not limited to, symmetrically disposed relative to the axis of the central through-hole  301  of the iron core body  31 , but can be disposed according to arbitrarily disposed according to actual needs. 
     In the present embodiment, a plurality of positioning grooves  331  can be disposed on an outer surface of the first plastic coating layer  33 , and the plurality of positioning grooves  331  can match with the plurality of magnetic sheets  32  one by one, respectively. Therefore, in the rotor assembly  30  of the present embodiment, when the second plastic coating layer  34  is formed on the first plastic coating layer  33  by a process of injection molding, a location of the magnetic sheet  32  in the iron core body  31  can be confirmed by the positioning groove  331  on the first plastic coating layer  33 , so as to facilitate magnetizing the magnetic sheet  32 . 
     Furthermore, the plurality of positioning grooves  331  can extend from an edge of the first plastic coating layer  33  to an opposite edge of the first plastic coating layer  33 . That is, the positioning groove  331  can runs along an outer surface of the first plastic coating layer  33  from the top surface of the first plastic coating layer  33  to the bottom surface of the first plastic coating layer  33 . Therefore, the magnetic sheet  331  can be entirely located. Moreover, a plurality of positioning holes  341  can be disposed referring to the plurality of positioning grooves  331 . 
     In details, each of the plurality of positioning grooves  331  can be disposed on a mid-vertical plane of corresponding one of the plurality of magnetic sheets. Therefore, a center line of the magnetic sheet can be accurately located with the positioning groove as a mark. 
     In the present embodiment, the rotor assembly  30  can include four magnetic sheets  32 . The four magnetic sheets  32  can be evenly disposed in the iron core body  31  along a circumference direction of the iron core body  31 . Correspondingly, four positioning grooves  331  can be disposed on the first plastic coating layer  33 . In the present disclosure, a number of the magnetic sheet  32  can be not limited to that shown in the figures. The rotor assembly can include two, three, five and even much more magnetic sheets  32 , and the plurality of magnetic sheets can be evenly disposed in the iron core body. 
     In the present embodiment, the plurality of positioning holes  341  can be disposed on the bottom surface of the second plastic coating layer  34 . The plurality of positioning holes  341  can match with the plurality of magnetic sheets  32  one by one, respectively. When the a magnetizing device is magnetizing the magnetic sheet  32  of the rotor assembly  30 , the plurality of positioning holes  341  on the second plastic coating layer  34  can be used to locate the magnetizing device, so as to facilitate locating the rotor assembly  30  on the magnetizing device, thereby facilitating magnetizing the magnetic sheet  32 . Wherein, the plurality of positioning holes  341  can be disposed on a center line of the magnetic sheet  32  as required. That is, the positioning hole  341  and the magnetic sheet  32  share a same center line, thereby preventing the magnetizing device from misplacing. 
     In details, in the present embodiment, the positioning holes  341  on the second plastic coating layer  34  can be disposed referring to the plurality of positioning grooves  331  on the first plastic coating layer  33 . That is, a line defined by a center of projection of the positioning groove  331  on the bottom surface of the second plastic coating layer  34  and a center of the bottom surface of the second plastic coating layer  34  is co-linear with the a line defined by a center of the positioning hole  341  and the center of the bottom surface. Therefore, the positioning holes  341  on the second plastic coating layer  34  can be located. In some embodiments, the positioning holes on the second plastic coating layer can be disposed according to actual needs, which will not be described in details herein. 
     In view of above, in an electric water pump  100  of the present disclosure, the magnetic sheet  32  is disposed in the iron core body  31 , and the first plastic coating layer  33  is used to replace the conventional magnetic ring  1 , so as to reduce consumption of the magnetic sheet  32 , thereby reducing the cost. At the same time, the second plastic coating layer  34  is used to replace the graphite bearing  2 , which can further reduce the cost of the rotor assembly  30 , thereby reducing whole cost of an electric water pump  100  using the rotor assembly  30  in the present disclosure. At the same time, the at least one protruding ribs  302  disposed on the first plastic coating layer  33  can improve connection strength between the second plastic coating layer  34  and the first plastic coating layer  33 . Therefore, when the rotor assembly  30  is assembled on the electric water pump  100  and rotate at a high speed, the first plastic coating layer  33  and the second plastic coating layer  34  will not separate from each other, thereby improving reliability of the rotor assembly  30  during use. 
     The technical features of the above-described embodiments may be combined in any combination. For the sake of brevity of description, all possible combinations of the technical features in the above embodiments are not described. However, as long as there is no contradiction between the combinations of these technical features, all should be considered as within the scope of this disclosure. 
     The above-described embodiments are merely illustrative of several embodiments of the present disclosure, and the description thereof is relatively specific and detailed, but is not to be construed as limiting the scope of the disclosure. It should be noted that a number of variations and modifications may be made by those skilled in the art without departing from the spirit and scope of the disclosure. Therefore, the scope of the disclosure should be determined by the appended claims.