Patent Publication Number: US-11664691-B2

Title: Electric pump and motor

Description:
CROSS-REFERENCE TO RELATED PATENT APPLICATIONS 
     This application is a Continuation of U.S. application Ser. No. 16/643,670, filed Mar. 2, 2020, which is a U.S. National Stage Application under 35 U.S.C. § 371 of PCT Application No. PCT/KR2018/009004, filed Aug. 8, 2018, which claims priority to Korean Patent Application Nos. 10-2017-0117159, filed Sep. 13, 2017, 10-2017-0117930, filed Sep. 14, 2017, 10-2017-0118455, filed Sep. 15, 2017 and 10-2017-0118456, filed Sep. 15, 2017, whose entire disclosures are hereby incorporated by reference. 
    
    
     TECHNICAL FIELD 
     Embodiments relate to an electric pump and a motor. 
     BACKGROUND ART 
     In general, an electric oil pump (EOP) is a device that supplies oil to a hydraulic line of a transmission or a braking device of a vehicle using a motor, in which circulation of oil is necessary. 
     In the case of a hybrid electric vehicle (HEV), an engine is stopped when the vehicle is stopped and thus it is difficult to supply a constant pressure to a transmission through a mechanical oil pump. Therefore, the HEV employs an electric oil pump that supplies oil through a motor. 
     Such an electric oil pump includes a suction port and a discharge port through which oil moves. 
     However, in an electric oil pump of the related art, a phenomenon occurs in which flow rate performance decreases sharply at a high flow rate and a flow rate is not uniform during the movement of a fluid. 
     A motor is a device that converts electrical energy into mechanical energy to generate a turning force and has been widely used in vehicles, household appliances, industrial equipment, and the like. 
     The motor may include a housing, a shaft, a stator disposed on an inner circumferential surface of the housing, a rotor installed on an outer circumferential surface of the shaft, and the like. Here, the stator of the motor causes electrical interaction with the rotor to induce rotation of the rotor. 
     Here, the rotor may be classified into a surface-mounted permanent magnet (SPM) type and an interior permanent magnet (IPM) type according to a coupling structure of a magnet installed in the rotor core. 
     In an IPM type rotor, a magnet is inserted into a rotor core and thus magnetic flux density is lower than that of an SPM type rotor in which a magnet is exposed on a surface thereof, and therefore, dynamic characteristics of a motor having the IPM type rotor may be lower than those of a motor having the SPM type rotor. 
     In particular, when barriers are formed at both sides of the magnet in the IPM type rotor, an H-field indicating the magnitude of a magnetic flux is low at inner corners of the magnet. Accordingly, when a magnetization process is performed after assembly of the magnet, HS characteristics indicating the strength of a magnetic force may not be satisfied and thus full magnetization cannot be achieved. In addition, when the motor is operated at a high temperature, a risk of irreversible demagnetization may occur additionally. 
     When the H-field is increased to satisfy the HS characteristics of the magnet so as to solve the above problems, an overcurrent may be supplied and thus a magnetizer and a magnetization yoke may be degraded. 
     Therefore, there is a need for a rotor which achieves full saturated magnetization of a magnet only with a certain amount of current without applying an overcurrent. 
     DISCLOSURE 
     Technical Problem 
     Embodiments are directed to providing an electric pump in which a shape of a suction port is changed to stabilize a flow of a fluid. 
     Embodiments are also directed to providing an electric pump capable of being detachably coupled with a bus bar through a fork-type terminal. 
     Embodiments are also directed to providing an electric pump in which a motor housing and a connector unit are connectable at accurate positions. 
     Other embodiments of the present invention are directed to providing a motor in which barriers are formed on a rotor core to achieve full magnetization of a magnet. 
     Other embodiments are directed to providing a motor in which an arrangement position of a barrier is determined by an arrangement angle and distance relative to a central point. 
     Aspects of the present invention are not limited thereto and other aspects not mentioned herein will be clearly understood by those of ordinary skill in the art from the following description. 
     Technical Solution 
     According to one aspect of the present invention, an electric pump includes a motor unit which includes a shaft, a rotor coupled to the shaft, and a stator disposed outside the rotor; a pump unit which includes a first rotor coupled to the motor unit and including a first lobe having gear teeth, and a second rotor disposed outside the first rotor and including a second lobe; and a second cover including a second surface on which the pump unit is disposed, wherein a second suction port and a second discharge port are disposed on the second surface, the second suction port provided on the second surface includes a third protrusion protruding toward an inner side of the second suction port, and an angle formed by a first line connecting the center of the first rotor and the center of the second rotor and a second line connecting the center of the first rotor and a distal end of the third protrusion is inversely proportional to the number of gear teeth of the first lobe. 
     The first line passing through the center of the first rotor and the center of the second rotor may be parallel to a third line connecting ends of the second suction port in a region adjacent to the third protrusion. 
     A distance between the first line and the second line may be proportional to a distance between the center of the first rotor and the center of the second rotor. 
     A first cover may be disposed between the motor unit and the pump unit, the first cover may include a first surface which accommodates the pump unit, the first surface may include a first suction port and a first discharge port, and the first suction port and the second suction port may have different shapes. 
     The second cover may include an inlet which communicates with the second suction port and an outlet which communicates with the second discharge port. 
     A third coupling hole may be formed in the center of the first rotor and engaged with the shaft, the shaft may have at least one cut surface, and the cut surface may match in shape with the third coupling hole. 
     According to another aspect of the present invention, an electric pump includes a motor unit including a shaft, a rotor provided with the shaft, a stator disposed outside the rotor, a bus bar disposed above the stator, and a motor housing which accommodates the rotor and the stator; and a connector unit disposed on the motor unit and including a power terminal coupled to a terminal of the bus bar, wherein the bus bar includes a bus bar terminal coupled with a coil wound around the stator or the rotor, and a bus bar body which insulates the bus bar terminal, an end of the power terminal diverges into a pair of contact portions, and the bus bar terminal is inserted between the contact portions to be electrically connected to the contact portions. 
     Divergence areas of the pair of contact portions may include a curved surface. 
     Each of the pair of contact portions may include a first region, a width of which increases at the divergence area; a second region which extends from the first region and a width of which decreases; and a third region which extends from the second region and a width of which increases, wherein a point at which the second region and the third region are connected to each other is in contact with the bus bar body. 
     The third region may include a curved surface. 
     The bus bar body may include a pair of first protrusions which guide the pair of contact portions. 
     The bus bar terminal may include a curved portion and be in surface contact with the pair of contact portions. 
     According to another aspect of the present invention, an electric pump includes a motor unit including a shaft, a rotor coupled to the shaft, a stator disposed outside the rotor, and a motor housing which accommodates the rotor and the stator; and a connector unit disposed on the motor unit, wherein the motor unit includes at least one hole, and the connector unit includes at least one second protrusion inserted into the at least one hole. 
     An end portion of the motor housing may include a protrusion having a certain area, the connector unit may include a connector body and a connector connection part facing the protrusion, the protrusion may be provided with the at least one hole, and the connector connection part may be provided with the at least one second protrusion inserted into the at least one hole. 
     The connector connection part may be connected to a side of the connector body and include a first connection portion on which the at least one second protrusion is disposed and a second connection portion connected at a certain angle to the first connection portion. 
     The connector connection part may include a plurality of grooves arranged such that opposite sides thereof are symmetric to each other, and the at least one second protrusion may be provided between the plurality of grooves. 
     The connector connection part may include a rib formed in a lengthwise direction, and the at least one second protrusion may be provided on the rib. 
     The at least one second protrusion may be provided in a cylindrical shape, and an upper end thereof may be inclined along a circumference of the at least one second protrusion. 
     According to another aspect of the present invention, a motor includes a shaft, a rotor including a hole in which the shaft is disposed, and a stator outside the rotor, wherein the rotor includes a rotor core and a magnet, the rotor core includes a main body, a pocket which is formed in the main body and in which the magnet is disposed, first barriers extending from both sides of the pocket, and second barriers formed between an inner circumferential surface of the main body and an outer circumferential surface of the main body, and a center (C 11 ) of the second barrier has a certain arrangement angle θ in a circumferential direction from a first line (L 11 ) passing through a center (CC) of the main body and a center of a width (W) of the magnet. 
     The arrangement angle θ may be calculated by the following equation: 
     
       
         
           
             
               
                 arctan 
                 ⁡ 
                 ( 
                 
                   
                     W 
                     / 
                     2 
                   
                   
                     D 
                     ⁢ 
                     1 
                     ⁢ 
                     1 
                   
                 
                 ) 
               
               ≤ 
               θ 
               ≤ 
               
                 arctan 
                 ⁡ 
                 ( 
                 
                   
                     W 
                     / 
                     2 
                   
                   
                     D 
                     ⁢ 
                     2 
                     ⁢ 
                     2 
                   
                 
                 ) 
               
             
             , 
           
         
       
     
     wherein W represents a width of the magnet, D 11  represents a distance from the center of the main body to an inner side surface of the magnet, and D 22  represents a distance from the center of the main body to an outer side surface of the magnet. 
     The second barrier may have a certain radius (R). 
     The inner side surface of the magnet may be disposed on a second line (L 22 ) passing through the center (CC) of the main body and the center (C 11 ) of the second barrier. 
     An arrangement distance D 33  from the center (CC) of the main body to the center (C 11 ) of the second barrier may be calculated by the following equation: 
     
       
         
           
             
               
                 
                   D 
                   ⁢ 
                   3 
                   ⁢ 
                   3 
                 
                 = 
                 
                   
                     D 
                     ⁢ 
                     1 
                     ⁢ 
                     1 
                   
                   
                     cos 
                     ⁢ 
                     θ 
                   
                 
               
               - 
               O 
               - 
               R 
             
             , 
           
         
       
     
     wherein O represents a distance between one point (P 1 ) on an outer circumferential surface of the second barrier disposed on the second line (L 22 ) and one point P 2  on the inner side surface of the magnet. 
     The second barrier may be formed to be long from an upper end of the main body to a lower end of the main body. 
     Two of the second barriers disposed to correspond to one magnet may be symmetrical to each other with respect to the first line (L 11 ). 
     Advantageous Effects 
     According to an embodiment, flow rate performance can be achieved even at a high flow rate. 
     Noise can be reduced by stabilizing the flow of a fluid. 
     Durability of a product can be increased by minimizing bubbles to be introduced into a region in which a fluid flows. 
     An additional process or structure for connecting a terminal and a bus bar of a motor can be skipped to reduce an assembly time and costs. 
     Components are replaceable by applying a detachable structure. 
     The reliability of assembly of a terminal and a bus bar may be secured using a position guide. 
     A connector unit can be connected at a designated position, thereby minimizing performance deviation for each product. 
     A manufacturing method can be simplified and process investment costs can be reduced by simplifying a shape of a motor housing for fixing a position. 
     In addition, in a motor according to another embodiment of the present invention, a second barrier can be formed in a rotor to adjust magnetic flux saturation of a rotor core during magnetization of a magnet. Accordingly, when the same current is supplied for magnetization, full magnetization of the magnet can be achieved by allowing a maximum H field in a region of the magnet. 
     In this case, an arrangement position of the second barrier on the rotor core can be adjusted by an arrangement angle and distance. 
     Various and beneficial advantages and effects of the present invention are not limited to the above description and will be more easily understood in the course of describing specific embodiments of the present invention. 
    
    
     
       DESCRIPTION OF DRAWINGS 
         FIG.  1    is a perspective view of an electric pump according to an embodiment of the present invention. 
         FIG.  2    is an exploded perspective view of  FIG.  1   , 
         FIG.  3    is a diagram illustrating a structure of a motor unit which is a component of  FIG.  1   , 
         FIG.  4    is a diagram illustrating a structure of a bus bar which is a component of  FIG.  1   , 
         FIG.  5    is a diagram illustrating a structure of a connector unit which is a component of  FIG.  1   , 
         FIG.  6    is a diagram illustrating an arrangement of power terminals included in the connector unit which is a component of  FIG.  1   , 
         FIG.  7    is a diagram illustrating a structure in which the bus bar and the power terminals of  FIG.  1    are connected to each other, 
         FIG.  8    is a diagram illustrating a structure of an end portion of the power terminal of  FIG.  7   , 
         FIG.  9    illustrates a bus bar terminal which is coupled to the power terminal in  FIG.  7    according to an embodiment, 
         FIG.  10    is a diagram illustrating a structure in which a motor housing and a connector unit of  FIG.  2    are connected to each other, 
         FIG.  11    is a diagram illustrating a first suction port and a first discharge port formed in a first cover of  FIG.  2   , 
         FIG.  12    is a diagram illustrating a second suction port and a second discharge port formed in a second cover of  FIG.  2   , 
         FIG.  13    is a diagram illustrating a structure of a pump unit in  FIG.  2   , 
         FIG.  14    is a diagram illustrating a state in which the pump unit is located on the first cover, 
         FIG.  15    is a diagram illustrating a state in which the pump unit is located on the second cover, 
         FIG.  16    is a diagram showing a change in flow rate performance when a shape of the second cover of  FIG.  15    is applied, 
         FIG.  17    is a longitudinal sectional view of a motor according to the embodiment, 
         FIG.  18    is a cross-sectional view taken along line A-A of  FIG.  17   , 
         FIG.  19    is a diagram illustrating a rotor core of a motor according to an embodiment, 
         FIG.  20    is a diagram illustrating region B of  FIG.  18   , 
         FIG.  21    is a diagram illustrating various embodiments of a second barrier of a rotor disposed in a motor according to an embodiment, 
         FIG.  22 A  and  FIG.  22 B  are diagrams showing a comparison of an H field of a rotor of a motor according to an embodiment with an H field of a rotor of a motor according to a comparative example, 
         FIG.  23 A  and  FIG.  23 B  are diagrams showing a comparison of a uniform magnetic flux line of a rotor of a motor according to an example with a uniform magnetic flux line of a rotor of a motor according to a comparative example, 
         FIG.  24 A  and  FIG.  24 B  are diagrams showing a comparison of magnetic flux density of a rotor of a motor according to an example with magnetic flux density of a rotor of a motor according to a comparative example. 
     
    
    
     MODES OF THE INVENTION 
     Various changes may be made in the present invention and various embodiments may be implemented, and certain embodiments will be illustrated in the drawings and described hereinafter. However, it should be understood that embodiments of the present invention are not limited to these embodiments and cover all modifications, equivalents, and alternatives falling within the idea and scope of embodiments. 
     As used herein, the terms “first,” “second,” etc. may be used herein to describe various elements but these elements are not limited by these terms. These terms are used only for the purpose of distinguishing one element from another. For example, a second element discussed below could be termed a first element without departing from the scope of embodiments. Similarly, a first element could be termed a second element. The terms “and/or” includes any one or any combination of a plurality of related listed items. 
     The terminology used herein is for the purpose of describing certain embodiments only and is not intended to be limiting of embodiments of the present invention. As used herein, the singular expressions are intended to include plural forms as well, unless the context clearly dictates otherwise. It will understood that the terms “comprise” and/or “comprising,” when used herein, specify the presence of stated features, integers, steps, operations, elements, components, or a combination thereof but do not preclude the presence or addition of one or more features, integers, steps, operations, elements, components, or a combination thereof. 
     When one element is referred to as being formed “on” or “under” another element in embodiments, it will be understood that the two elements are formed to be in direct contact with each other or to be in indirect contact with each other while one or more elements are interposed therebetween. The expression “on or under one element” should be understood to mean not only an upward direction but also a downward direction with respect to the element. 
     Hereinafter, embodiments will be described in detail with reference to the accompanying drawings, and the same or corresponding components will be denoted by the same reference numerals regardless of figure number and will not be redundantly described. 
       FIGS.  1  to  16    clearly illustrate only main features for conceptually clear understanding of the present invention, and thus, it is expected that various modifications may be made in the drawings and the scope of the present invention should not be limited by specific shapes shown in the drawings. 
       FIG.  1    is a perspective view of an electric pump according to an embodiment of the present invention.  FIG.  2    is an exploded perspective view of  FIG.  1   . 
     Referring to  FIGS.  1  and  2   , the electric pump according to the embodiment of the present invention may include a motor unit  100 , a connector unit  200 , a first cover  300 , a pump unit  400 , and a second cover  500 . 
     The motor unit  100  generates power to transfer the power to the electric pump, and the connector unit  200  is provided on the motor unit  100  to supply the power to the motor unit  100 . 
     The connector unit  200  is provided on the motor unit  100  and may include a connector body  210  on a motor housing  150  and a connector connection part  230  connected to a side of the connector body  210 . A first through hole  211  may be provided, through which a shaft  110  of the motor unit  100  passes. 
     The first cover  300  is disposed between the connector unit  200  and the pump unit  400  and includes a second through hole  340  through which the shaft  110  of the motor unit  100  passes. 
     The pump unit  400  may be disposed between the first cover  300  and the second cover  500  and may be provided with a third through hole to which the shaft  110  passing through the first cover  300  is coupled. 
     The second cover  500  may be disposed on a front side of the pump unit  400  and combined with the first cover  300  to accommodate the pump unit  400 . 
       FIG.  3    is a diagram illustrating a structure of the motor unit  100  of  FIG.  1   . 
     Referring to  FIG.  3   , the motor unit  100  transmits power to the pump unit  400  and includes the shaft  110 , a rotor  120 , a stator  130 , a bus bar  140 , and a motor housing  150 . 
     The shaft  110  may be coupled to the rotor  120 . When power is supplied to cause electromagnetic interaction between the rotor  120  and the stator  130 , the rotor  120  rotates and the shaft  110  rotates in connection therewith. The shaft  110  may be supported by a bearing. 
     The rotor  120  is disposed inside the stator  130 . The rotor  120  may include a rotor core and a magnet coupled to the rotor core. The rotor  120  may be classified into the following types according to a coupling method of the rotor core and the magnet. 
     The rotor  120  may be embodied as a type in which the magnet is coupled to an outer circumferential surface of the rotor core. In this type of the rotor  120 , a separate can member may be coupled to the rotor core to prevent separation of the magnet and increase the coupling of the magnet. Alternatively, the magnet and the rotor core may be double injected and integrally formed. 
     The rotor  120  may embodied as a type in which the magnet is coupled to the inside of the rotor core. In this type of the rotor  120 , the inside of the rotor core may be provided with a pocket into which the magnet is inserted. 
     There may be two types of rotor core. 
     First, a rotor core may be formed by stacking a plurality of thin steel plates together. In this case, the rotor core may be formed as one piece that does not form a skew angle or as a form in which a plurality of unit cores forming a skew angle are combined together. 
     Secondly, a rotor core may be in the form of a single container. In this case, the rotor core may be formed as one piece that does not form a skew angle or as a form in which a plurality of unit cores forming a skew angle are combined together. 
     A magnet may be included inside or outside each of the unit cores. 
     The stator  130  causes electrical interaction with the rotor  120  to induce the rotation of the rotor  120 . A coil  131  may be wound around the stator  130  to cause interaction with the rotor  120 . A specific configuration of the stator  130  for winding a coil around the stator  30  will be described below. 
     The stator  130  may include a stator core with teeth. The stator core may be provided with a ring-shaped yoke and teeth may be provided on the yoke to face the center of the stator core. The teeth may be provided around the yoke at regular intervals. The stator core may be formed by stacking a plurality of thin steel plates together. Alternatively, the stator core may be formed by coupling or connecting a plurality of divided cores to each other. 
     The bus bar  140  may be disposed on an upper end of the stator  130  to be electrically connected to the coil  131 . The bus bar  140  may include a bus bar body  141  and a bus bar terminal  143 . The bus bar body  141  may be embodied as a ring-shaped mold member. The bus bar terminal  143  is connected to an end of the coil  131  lifted from an assembly of the stator  130  or an assembly of the rotor  120 . 
     The bus bar  140  may electrically connect coils  131  wound around the stator  130  or the rotor  120  to be electrically connected to U-, V-, or W-phase power terminals  250 . 
     The motor housing  150  may be formed in a cylindrical shape such that the stator  130  may be coupled to an inner wall thereof. An upper portion of the motor housing  150  may be open and a lower portion thereof may be closed. The lower portion of the motor housing  150  may be provided with a bearing mounting space for accommodating a bearing for supporting the lower portion of the shaft  110 . 
       FIG.  4    is a diagram illustrating a structure of the bus bar  140  of  FIG.  1   . 
     The bus bar terminal  143  may be formed as an arc and include a plurality of connection terminals  143   a  to be coupled to the coil  131 . In one embodiment, three bus bar terminals  143  may be provided to electrically connect the coil  131  wound around the stator  130 , and each of the three bus bar terminals  143  may be delta-connected. 
       FIG.  5    is a diagram illustrating a structure of the connector unit  200  of  FIG.  1   .  FIG.  6    is a diagram illustrating an arrangement of the power terminals  250  included in the connector unit  200  of  FIG.  1   . 
     Referring to  FIGS.  5  and  6   , the connector unit  200  may include a connector body  210  disposed on the motor unit  100  and a connector connection part  230  connected to a side of the body of the connector unit  200  to receive power. 
     The connector body  210  may be provided with the first through hole  211  through which the shaft  110  passes, and a region thereof may be inserted into the motor housing  150 . A sealing part may be provided at a side of the connector body  210  to maintain airtight coupling of the connector body  210  with the motor housing  150 . 
     A plurality of power terminals  250  may protrude outward from the connector body  210 . In one embodiment, three power terminals  250  may be provided to be each electrically connected to one of the bus bar terminals  143 . 
     The connector connection part  230  is connected to the connector body  210  and may receive external power. In one embodiment, the power terminals  250  protruding outward from the connector body  210  may be provided in a bent shape to pass through the connector body  210  and the connector connection part  230 . The shape of the power terminals  250  is not limited and may be variously changed according to the shape of the connector connection part  230  connected to the connector body  210 . 
       FIG.  7    is a diagram illustrating a structure in which the bus bar  140  and the power terminals  250  of  FIG.  1    are connected to each other.  FIG.  8    is a diagram illustrating a structure of an end portion of the power terminal  250  of  FIG.  7   . 
     Referring to  FIGS.  7  and  8   , bus bar terminals  143  may be inserted into the power terminals  250  to be electrically connected to the power terminals  250 . 
     An end of each of the power terminals  250  may branch into a pair of contact portions  251 . Ends of the pair of contact portions  251  are spaced apart from each other, and the bus bar terminal  143  may be inserted into a space between the pair of contact portions  251 . A distance d 1  between the ends of the pair of contact portions  251  spaced apart from each other may be less than a width of the bus bar terminal  143  and may be elastically deformed when the bus bar terminal  143  is inserted between the pair of contact portions  251 . 
     In one embodiment, the distance d 1  between the pair of contact portions  251  increases in a first region A 1  starting from a point where the power terminal  250  branches, decreases in a second region A 2 , and increases again in a third region A 3 . The pair of contact portions  251  are designed according to a stress analysis result to prevent cracks from occurring due to an expansion force applied when the pair of contact portions  251  are spread apart to be brought into contact with the bus bar terminal  143 . As the stress analysis result, damage caused by stress may be minimized by setting, to a curved region, a branch region X 1  to which maximum stress is applied. 
     A section changed from the second region A 2  to the third region A 3  is in contact with the bus bar terminal  143 , and the third region A 3  may include a curved portion to facilitate the insertion of the bus bar terminal  143 . 
     The bus bar body  141  may be provided with a plurality of first protrusions  141   a  to guide the position of the pair of contact portions  251 . The first protrusions  141   a  may be arranged in pairs and protrude upward from the bus bar body  141 . 
     The pairs of first protrusions  141   a  may be spaced apart from each other, and the bus bar terminal  143  may pass between the first protrusions  141   a . The power terminal  250  may be inserted between the first protrusions  141   a , and the bus bar terminal  143  passing between the first protrusions  141   a  may be inserted into the contact portions  251  to be in contact with the contact portions  251 . 
     The first protrusions  141   a  may not only guide the position of the bus bar terminal  143  but also prevent the separation or movement of the contact portions  251  in contact with the bus bar terminal  143  to maintain an electrically stable contact. A shape of the first protrusions  141   a  is not limited but may be changed in various shapes to support both sides of the contact portions  251 . 
       FIG.  9    illustrates the bus bar terminal  143  which is coupled to the power terminal in  FIG.  7    according to an embodiment. 
     Referring to  FIG.  9   , both sides of the bus bar terminal  143  in contact with the contact portions  251  may include a curved portion  143   b . The curved portion  143   b  may be provided to match in shape to a contact side of the contact portion  251  in contact therewith in a curved form. 
     The curved portion  143   b  may facilitate the insertion of the contact portion  251  into the bus bar terminal  143  and maintain a stable coupling state by increasing a contact area through shape matching. 
       FIG.  10    is a diagram illustrating a structure in which the motor housing  150  and the connector unit  200  of  FIG.  2    are connected to each other. 
     Referring to  FIG.  10   , the connector unit  200 , which is a component of the present invention, may be disposed on the motor housing  150 . Various components, such as the power terminal  250 , a substrate, and a hall-integrated circuit (IC), are disposed on the connector unit  200  and a position thereof should be fixed when the power terminal  250  is combined with the motor unit  100 . 
     In the present invention, in order to fix the position of the connector unit  200 , the motor housing  150  may be provided with at least one hole  151   a  and the connector unit  200  may be provided with at least one second protrusion  231   a . The positions of the hole  151   a  and the second protrusion  231   a  may respectively intersect those of the connector unit  200  and the motor housing  150 , and a description about the formation of the hole  151   a  in the connector unit  200  and the formation of the second protrusion  231   a  on the motor housing  150  will be omitted. 
     A protrusion  151  may be provided on a side of the motor housing  150 . The protrusion  151  may extend from an upper portion of the motor housing  150 , and the hole  151   a  may be formed in a region of a center of the protrusion  151 . A shape of the hole  151   a  is not limited but may have the same cross-sectional shape as the second protrusion  231   a  so that the second protrusion  231   a  of the connector unit  200  may be inserted into the hole  151   a.    
     The connector connection part  230  may include a first connection portion  231  and a second connection portion  233 . 
     The first connection portion  231  is connected to a side of the connector body  210  and is disposed to face the protrusion  151  when the connector connection part  230  and the motor housing  150  are coupled to each other. In this case, the first connector portion  231  may be provided with the second protrusion  231   a , and the second protrusion  231   a  may be inserted into the hole  151   a  to fix the position of the connector unit  200 . 
     In one embodiment, the second protrusion  231   a  may be provided in a cylindrical shape, the upper portion of which is inclined to be easily inserted into the hole  151   a.    
     In addition, the first connector portion  231  may be provided with a rib  231   b  in a region at the center thereof, and the second protrusion  231   a  may be disposed on the rib  231   b . The rib  231   b  may be arranged in a specific structure or may be formed by coring a basic structure. The rib  231   b  may be disposed in a lengthwise direction of the first connection portion  231  to resist bending or warping of the first connection portion  231 . 
     A plurality of grooves  231   c  may be provided at both sides of the second protrusion  231   a  of the first connection portion  231 . In one embodiment, the plurality of grooves  231   c  may be arranged at regular intervals and in a direction perpendicular to a direction of the rib  231   b.    
     The second connection portion  233  may be connected to the first connection portion  231  to receive external power. In one embodiment, the second connection portion  233  may be connected at a certain angle to the first connection portion  231 . An angle at which the second connection portion  233  and the first connection portion  231  are connected to each other may be modified according to an angle at which the second connection portion  233  is installed to receive power. 
       FIG.  11    is a diagram illustrating a first suction port  320  and a first discharge port  330  formed in the first cover  300  of  FIG.  2   .  FIG.  12    is a diagram illustrating a second suction port  520  and a second discharge port  530  formed in the second cover  500  of  FIG.  2   .  FIG.  13    is a diagram illustrating a structure of the pump unit  400  of  FIG.  2   .  FIG.  14    is a diagram illustrating a state in which the pump unit  400  is positioned in the first cover  300 .  FIG.  15    is a diagram illustrating the pump unit  400  is positioned in the second cover  500 . 
     Referring to  FIGS.  11  to  15   , the pump unit  400  may be disposed between the first cover  300  and the second cover  500 . 
     The pump unit  400  is inserted into a space, to which a fluid is supplied, between the second cover  500  and the first cover  300  and pumps oil by receiving power from the motor unit  100 . The first cover  300  and the second cover  500  are combined together to form a space in which the pump unit  400  is located. The first cover  300  and the second cover  500  are described separately according to functional characteristics but may be connected integrally to each other. 
     One side of the first cover  300  may be in contact with the connector unit  200  and the other side thereof may include a first side  310  for accommodating the pump unit  400 . 
     The first side  310  may include the first suction port  320  and the first discharge port  330 . The first suction port  320  and the first discharge port  330  may each have a conventional port shape. 
     The second cover  500  may include a second side  510  on which the pump unit  400  is disposed, and the second side  510  may include the second suction port  520  and the second discharge port  530 . The second suction port  520  may include an inlet  521 , which communicates with the second suction port  520  and through which oil is introduced, and an outlet  531  which communicates with the second discharge port  530 . 
     The second suction port  520  and the second discharge port  530  may be formed in an arc shape and provided to be tapered from one side to the other side. In addition, the second suction port  520  and the second discharge port  530  may be arranged such that a wider portion of the second suction port  520  faces a wider portion of the second discharge port  530  and a narrower portion of the second suction port  520  faces a narrower portion of the second discharge port  530 . 
     The second discharge port  530  may have a conventional port shape. 
     The second suction port  520  may include a third protrusion  523  protruding inward. The third protrusion  523  may protrude toward a space forming the second suction port  520  from an end of the second suction port  520  farther from the center of the first rotor  410  among ends of the second suction port  520 . 
     The suction port and discharge port are formed respectively on the first cover  300  and the second cover  500  to guide a fluid to be smoothly suctioned and discharged by the pump unit  400 . These suction port and discharge ports are arranged by partitioning a space. This is to prevent movement of the fluid due to a pressure difference. 
     Referring to  FIG.  13   , the pump unit  400  is disposed between the first cover  300  and the second cover  500  and pumps a fluid by receiving power from the motor unit  100 . The pump unit  400  may include the first rotor  410  and the second rotor  120 . The first rotor  410  may be referred to as an inner rotor  120  and the second rotor  430  may be referred to as an outer rotor  120 . 
     A turning force is directly applied to the first rotor  410  from the motor unit  100  because the shaft  110  is coupled to a central portion of the first rotor  410 . In one embodiment, the shaft  110  includes at least one cut surface  111  and may be inserted into a third coupling hole  440  formed in the center of the first rotor  410 . The third coupling hole  440  may match in shape with the shaft  110  to which the third coupling hole  440  is inserted, thereby preventing the first rotor  410  from running idle during rotation of the shaft  110 . 
     The second rotor  430  is disposed outside the first rotor  410 . In addition, in the first rotor  410 , a first lobe  411  with N gear teeth facing outward in a radial direction with respect to the center of rotation may be provided in a circumferential direction. The second rotor  430  may be provided with N+1 second lobes  431  facing inward in the radial direction. In this case, the second lobe  431  may be disposed to be caught by the first lobe  411 . As the first rotor  410  rotates, the second rotor  430  rotates in connection with the first rotor  410 . 
     Meanwhile, a diameter of a dedendum circle C 1  of the first rotor  410  (hereinafter referred to as “D 1 ”) and a diameter of a dedendum circle C 2  of the second rotor  430  (hereinafter referred to as “D 2 ”) are criteria for forming a space for pumping oil. 
     In the present invention, oil may be stably supplied in high-speed regions by changing the shape of a suction port. 
       FIG.  14    illustrates a contact structure between the first suction port  320  and the first discharge port  330  which are formed on the first cover  300 , similarly to a structure of the related art. 
     However, when the first cover  300  and the second cover  500  are combined together, the first suction port  320  and the second suction port  520  face each other and the first discharge port  330  and the second discharge port  530  face each other. In this case, the first suction port  320  and the second suction port  520  may be arranged in different shapes. 
     Referring to  FIG.  15   , the first rotor  410  and the second rotor  430  may be disposed such that the centers thereof do not coincide with each other. When a center P 1  of the first rotor  410  and a center P 2  of the second rotor  430  are projected onto the second cover  500 , an angle formed by a first line L 1  connecting the center P 1  of the first rotor  410  and the center P 2  of the second rotor  430  and a second line L 2  connecting the center P 1  of the first rotor  410  and an end of the third protrusion  523  may be inversely proportional to the number of gear teeth. A flow rate and velocity of a fluid to be introduced may be determined by an arrangement position of the third protrusion  523 . 
     In one embodiment, an angle θ formed by the first line L 1  and the second line L 2  may be calculated by Equation 1 below. 
     
       
         
           
             
               
                 
                   θ 
                   = 
                   
                     
                       3 
                       ⁢ 
                       6 
                       ⁢ 
                       0 
                       ⁢ 
                       W 
                     
                     
                       N 
                       * 
                       2 
                     
                   
                 
               
               
                 
                   [ 
                   
                     Equation 
                     ⁢ 
                         
                     1 
                   
                   ] 
                 
               
             
           
         
       
     
     Here, N represents the number of gear teeth formed on the first rotor  410 . 
     The position of the end of the third protrusion  523  may be determined according to the angle θ formed by the first line L 1  and the second line L 2 . 
     In one embodiment, when the first rotor  410  includes five gear teeth as illustrated in  FIG.  13   , θ may be set to 36 degrees. 
     In this case, θ may be changed within a range of 5%. 
     A third line L 3  connecting ends of the second suction port  520  in a region adjacent to the third protrusion  523  may be parallel to the first line L 1 . Two recessed regions are formed at ends of the second suction port  520  due to the third protrusion  523  formed inside the second suction port  520 , and the third line L 3  connects innermost sides of the two recessed regions. 
     In addition, when the first line L 1  and the third line L 3  are parallel to each other, a distance d 2  between the first line L 1  and the third line L 3  is proportional to a distance between the center P 1  of the first rotor  410  and the center P 2  of the second rotor  430 . 
     In one embodiment, the distance d 2  between the first line L 1  and the third line L 3  may be calculated by Equation 2 below.
 
 e* 1.25&lt; d 2&lt; e* 1.35  [Equation 2]
 
     Here, e represents the distance between the center P 1  of the first rotor  410  and the center P 2  of the second rotor  430 . 
     Therefore, the arrangement position of the third protrusion  523  of the second suction port  520  may be determined by the number N of gear teeth of the first rotor  410  and a distance e between the center P 1  of the first rotor  410  and the center P 2  of the second rotor  430 . 
       FIG.  16    is a diagram showing a change in flow rate performance when the shape of the second cover of  FIG.  15    is applied. 
     Referring to  FIG.  16   , in the related art, an increase in flow rate decreased when the speed of rotation was 4000 rpm or more and decreased greatly when the speed of rotation exceeded 5000 rpm. 
     However, when the shape of the second cover  500  according to an embodiment of the present invention was applied, a constant flow rate increase was secured even when the speed of rotation exceeded 4000 rpm and was continuously maintained even when the speed of rotation exceeded 5000 rpm. 
       FIG.  17    is a longitudinal sectional view of a motor according to the embodiment.  FIG.  18    is a cross sectional view taken along line A-A of  FIG.  17   . 
     Referring to  FIGS.  17  and  18   , a motor  1001  according to an embodiment may include a housing  1100 , a bracket  1200 , a rotor  1300 , a stator  1400 , and a shaft  1500 . Here, the bracket  1200  may be disposed to cover an open upper portion of the housing  1100 . 
     The housing  1100  and the bracket  1200  may form an exterior of the motor  1001 . Here, the housing  1100  may be formed in a cylindrical shape having an opening thereon. 
     Therefore, an accommodation space may be formed in the motor  1101  due to coupling of the housing  1100  and the bracket  1200 . As illustrated in  FIG.  17   , the rotor  1300 , the stator  1400 , the shaft  1500 , and the like may be disposed in the accommodation space. 
     The housing  1100  may be formed in a cylindrical shape so that the stator  1400  may be supported on an inner circumferential surface of the housing  1100 . A pocket portion for accommodation of a bearing  1060  supporting a lower portion of the shaft  1500  may be provided at the bottom of the housing  1100 . 
     The bracket  1200  disposed on the top of the housing  1100  may also be provided with a pocket portion for supporting an upper portion of the shaft  1500 . The bracket  1200  may include a hole or a groove into which a connector, to which an external cable is connected, is inserted. 
     The rotor  1300  is disposed inside the stator  1400 . Here, an inner side with respect to a radial direction (a y-axis direction) refers to a direction toward a center CC with respect to the center CC, and an outer side refers to a direction opposite that of the inner side. The center CC is the center of rotation of the shaft  1500  and may be a center CC of the rotor  1300 . 
     The rotor  1300  may include a rotor core  1310  and a magnet  1320 . 
     Here, the rotor  1300  may be an interior permanent magnet (IPM) type rotor in which the magnet  1320  is coupled to the inside of the rotor core  1310 . Accordingly, the rotor  1300  may include a pocket into which the magnet  1320  is inserted. 
       FIG.  19    is a diagram illustrating a rotor core of a motor according to an embodiment. 
     Referring to  FIG.  19   , a rotor core  1310  may include a main body  1311 , a pocket  1312 , a first barrier  1313 , a second barrier  1314 , and a hole  1315 . 
     The main body  1311  forms an exterior of the rotor core  1310 . 
     Here, the main body  1311  may be formed by stacking a plurality of thin steel plates together. 
     A magnet  1320  is disposed in the pocket  1312 . 
     As illustrated in  FIG.  19   , a plurality of pockets  1312  may be formed to be spaced apart from each other in a circumferential direction with respect to a center CC of the rotor core  1310 . Accordingly, magnets  1320  may be disposed in the circumferential direction with respect to the center CC of the rotor core  1310 . In this case, the magnets  1320  may be inserted into the pockets  1312 . 
     The first barrier  1313  may extend from both sides of the pocket  1312 . As illustrated in  FIG.  18   , when the magnets  1320  are disposed in the pockets  1312 , the first barriers  1313  may be disposed at both sides of the magnets  1320 . 
     An air layer may be formed on the first barrier  1313 . Accordingly, the first barrier  1313  serves as a flux barrier to prevent a short circuit and a leakage of magnetic flux. 
     However, when only the first barrier  1313  is disposed on the main body  1311  without the second barrier  1314 , the magnet  1320  may not be fully magnetized when the magnet  1320  is magnetized using only a certain amount of a current. Here, the magnetization refers to applying, to a magnet, an external magnetic field about 3 to 4 times a coercive force of the magnet. In this case, a high current is used to generate the external magnetic field. In particular, when the magnet is an NdFeB-based rare earth magnet, a peak value of a magnetizing field is determined by saturation magnetic flux density. 
     When a certain current is applied, the second barrier  1314  adjusts magnetic flux saturation of the main body  1311  so that a maximum H field may be present in the magnet  1320 . Accordingly, the magnet  1320  may be fully magnetized. 
       FIG.  20    is a diagram illustrating region B of  FIG.  18   , and the region B is part of the rotor  1300 . 
     Referring to  FIGS.  18  and  20   , a plurality of second barriers  1314  may be arranged in the circumferential direction. For example, two second barriers  1314  may be arranged adjacent to one magnet  1320 . Here, the arrangement of the two second barriers  1314  adjacent to one magnet  1320  may be understood to mean that the second barriers  1314  are arranged such that outer circumferential surfaces thereof are spaced a certain distance from the magnet  1320 . 
     The second barriers  1314  may be formed between an inner circumferential surface  311   a  and an outer circumferential surface  311   b  of the main body  1311 . As illustrated in  FIG.  20   , the second barriers  1314  may be formed between the inner circumferential surface  311   a  of the main body  1311  and an inner side  321  of the magnet  1320 . 
     The second barrier  1314  may be formed to have a circular cross section having a certain radius R. That is, a size of the second barrier  1314  may be defined by the radius R. Here, an example in which the second barrier  1314  has a circular cross section has been described above but embodiments are not limited thereto. As illustrated in  FIG.  21   , the second barrier  1314  may be provided as a polygonal shape, such as a hemispherical shape, an ellipse shape, a tetragonal shape or a hexagonal shape, or a bent tetragonal shape in consideration of an arrangement position of the second barrier  1314 . 
     The second barriers  1314  may be disposed to be symmetric to each other with respect to a first line L 11 . As illustrated in  FIG.  20   , two second barriers  1314  disposed to correspond to one magnet  1320  may be symmetric to each other with respect to the first line L 11 . Here, the first line L 11  is a line passing through the center CC of the main body  1311  and the center of a width W of the magnet. 
     The arrangement position of the second barrier  1314  may be defined by an arrangement angle θ and an arrangement distance D 33  from the center CC of the rotor core  1310 . 
     A center C 11  of the second barrier  1314  may have a certain arrangement angle θ with respect to the first line L 11  in the circumferential direction. For example, the arrangement angle θ may be an angle formed by the first line L 11  and a second line L 22  passing through the center CC of the main body  1311  and the center C 11  of the second barrier  1314 . In this case, an included angle between the first line L 11  and the second line L 22  is an angle with respect to the center CC. 
     In this case, the inner side  1321  of the magnet  1320  may be disposed on the second line L 22  passing through the center CC of the main body  1311  and the center C 11  of the second barrier  1314 . As illustrated in  FIG.  20   , one point P 1  on the outer circumferential surface of the second barrier  1314  and one point P 2  on the inner side  321  of the magnet  1320  may be disposed on the second line L 22 . 
     The arrangement angle θ may be calculated by Equation 3 below. 
     
       
         
           
             
               
                 
                   
                     arctan 
                     ⁡ 
                     ( 
                     
                       
                         W 
                         / 
                         2 
                       
                       
                         D 
                         ⁢ 
                         1 
                         ⁢ 
                         1 
                       
                     
                     ) 
                   
                   ≤ 
                   θ 
                   ≤ 
                   
                     arctan 
                     ⁡ 
                     ( 
                     
                       
                         W 
                         / 
                         2 
                       
                       
                         D 
                         ⁢ 
                         2 
                         ⁢ 
                         2 
                       
                     
                     ) 
                   
                 
               
               
                 
                   [ 
                   
                     Equation 
                     ⁢ 
                         
                     3 
                   
                   ] 
                 
               
             
           
         
       
     
     As illustrated in  FIG.  20   , W represents a width of a magnet, D 11  represents the distance from the center of a main body to an inner side surface of the magnet, and D 22  represents the distance from the center of the main body to an outer side surface of the magnet. 
     For example, when the rotor  1300 , which is an IPM type, is designed, the arrangement angle θ is less than 25.3 degrees and greater than 20.7 degrees when W is 9.8 mm, D 11  is 10.375 mm, and D 22  is 12.95 mm. Accordingly, the arrangement angle θ of the second barrier  1314  may be designed to be an angle between 20.7 degrees and 25.3 degrees. 
     The arrangement distance D 33  may be calculated by Equation 4 below. Here, the arrangement distance D 33  is a distance from the center CC of the main body  1311  to the center of the second barrier  1314 . 
     
       
         
           
             
               
                 
                   
                     
                       D 
                       ⁢ 
                       3 
                       ⁢ 
                       3 
                     
                     = 
                     
                       
                         D 
                         ⁢ 
                         1 
                         ⁢ 
                         1 
                       
                       
                         cos 
                         ⁢ 
                         θ 
                       
                     
                   
                   - 
                   O 
                   - 
                   R 
                 
               
               
                 
                   [ 
                   
                     Equation 
                     ⁢ 
                         
                     4 
                   
                   ] 
                 
               
             
           
         
       
     
     As illustrated in  FIG.  20   , O represents the distance between one point P 1  on the outer circumferential surface of the second barrier  1314  and one point P 2  on the inner side  321  of the magnet  1320 , which are located on the second line L 22 . 
     As described above, when the arrangement angle θ is set to 22 degrees to be within a range of the arrangement angle θ, R is set to 0.5 mm, and O is set to 0.2 mm, which are design parameters, the arrangement distance D 33  is determined to be 10.5 mm according to Equation 4 above. 
     Therefore, the arrangement position of the second barrier  1314  is determined by the placement angle θ of 22 degrees and the placement distance D 33  of 10.5 mm. 
     When the arrangement angle θ is set to 21.5 degrees to be within the range of the arrangement angle θ and design parameters R and O are respectively set to 1.0 mm and 0.4 mm, the arrangement distance D 33  is determined to be 9.75 mm according to Equation 4 above. 
     Therefore, the arrangement position of the second barrier  1314  is determined by the placement angle θ of 21.5 degrees and the placement distance D 33  of 9.75 mm. 
     The second barrier  1314  may be formed to be long from an upper end of the main body  1311  to a lower end of the main body  1311 . However, the present invention is not limited thereto, and a length of the second barrier  1314  in an axial direction (an x-axis direction) may be the same as a length of the magnet  1320  in the axial direction (the x-axis direction). Here, an air layer may be formed on the second barrier  1314 . 
     The hole  1315  may be formed in a central portion of the body  315 . Accordingly, the shaft  1500  may be coupled to the hole  1315 . 
     The magnet  1320  may be provided in the form of a tetragonal pillar extending from the upper end of the rotor core  1310  to the lower end of the rotor core  1310 . An example in which six magnets  1320  are disposed in the motor  1001  has been described above, but the embodiments are not limited thereto. 
     In this case, the magnitude of an external magnetic field required to magnetize the magnets  1320  varies according to energy density, coercive force, saturation magnetic flux density, etc. of a material of the magnets  1320 . 
       FIG.  22    is a diagram showing a comparison of an H field with respect to a rotor of a motor according to an example with an H field with respect to a rotor of a motor according to a comparative example.  FIG.  22 A  is a diagram illustrating the H field of the motor according to the example, and  FIG.  22 B  is a diagram illustrating the H field of the motor according to the comparative example. Here, a motor  1002  provided as the comparative example is different from the motor  1001  in terms of the presence of and an arrangement position of the second barrier  314 . 
     Referring to  FIG.  22   , when a magnetization peak current of 10.26 kA is supplied to the motor  1001  and the motor  1002  of the comparative example, an H field of the magnet  1320  of the motor  1001  is 1.8734*10{circumflex over (6)} A/m and an H field of the motor  1002  of the comparative example is 1.6465*10{circumflex over (6)} A/m. In this case, the radius R of the second barrier  1314  is 1.0 mm. 
     That is, in the case of the motor  1001 , a magnitude of the H field is increased by about 13.8% due to the second barrier  1314 . Accordingly, a magnetizing current of the motor  1001  may be reduced from 10.26 kA to 8.84 kA. That is, the motor  1002  of the comparative example to which 10.26 kA is applied and the motor  1001  to which 8.84 kA is applied have the same magnetization performance. 
     Therefore, the lowest H field of the motor  1001  with the second barrier  1314  increases and thus magnetization power of the motor  1001  is improved compared to the motor  1002  of the comparative example. In addition, a local non-magnetized region of the magnet  1320  decreases. 
     Meanwhile, the H field may be adjusted by the radius R of the second barrier  1314 . That is, as the radius R of the second barrier  1314  is adjusted, the arrangement distance D 3  is adjusted and thus a magnetization performance difference occurs. 
     When the radius R of the second barrier  1314  is adjusted to 0.5 mm and a magnetizing peak current of 10.26 kA is supplied to the motor  1001  and the motor  1002  of the comparative example, an H field of the magnet  1320  of the motor  1001  is 1.8288*10{circumflex over (6)} A/m and an H field of the motor  1002  of the comparative example is 1.6465*10{circumflex over (6)} A/m. 
     That is, in the case of the motor  1001 , the magnitude of the H field is improved by about 11.1% due to the second barrier  1314 . 
     Accordingly, the second barrier  1314  of the motor  1001  may increase the magnitude of a magnetization field in the magnet  1320 , thereby increasing a magnetization feature of the magnet  1320 . In addition, the arrangement distance D 3  is adjusted by the radius R of the second barrier  1314 . 
       FIG.  23    is a diagram showing a comparison of a uniform magnetic flux line of a rotor of a motor according to an example with a uniform magnetic flux line of a rotor of a motor according to a comparative example.  FIG.  23 A  is a diagram illustrating the uniform magnetic flux line of the motor of the example, and  FIG.  23 B  is a diagram illustrating the uniform magnetic flux line of the motor of the comparative example. 
     Referring to  FIG.  23   , a second barrier  1314  of a motor  1001  causes a change in magnetic resistance to change a magnetic flux path. In particular, the second barrier  1314  with an air layer has low permeability and thus a magnetic flux path in the rotor core  1310  may be greatly changed. Accordingly, a magnetic flux is concentrated at an inner edge of the magnet  1320  and thus the motor  1001  has a higher magnetic flux density distribution than the motor  1002  of the comparative example. 
       FIG.  24    is a diagram showing a comparison of magnetic flux density of a rotor of a motor according to an example with magnetic flux density of a rotor of a motor according to a comparative example.  FIG.  24 A  is a diagram illustrating an H field of the motor of the example, and  FIG.  24 B  is a diagram illustrating an H field of the motor of comparative example. 
     Referring to  FIG.  24   , the lowest magnetic flux density of the motor  1001  is higher than that of the motor  1002  of the comparative example. Accordingly, a magnitude of an external magnetic field applied to an inner corner of the magnet  1320  increases. 
     The stator  1400  may be supported by the inner circumferential surface of the housing  1100 . The stator  1400  is disposed outside the rotor  1300 . That is, the rotor  1300  may be disposed on an inner side of the stator  1400 . 
     Referring to  FIGS.  17  and  18   , the stator  1400  may include a stator core  1410  and a coil  1420 . Here, the stator core  1410  may be formed by stacking a plurality of thin steel plates together. Alternatively, the stator core  1410  may be formed by coupling or connecting a plurality of split cores to each other. 
     The stator core  1410  may include a yoke  1411  and teeth  1412 . 
     The yoke  1411  may be formed in a cylindrical shape. 
     The teeth  1412  may be disposed to protrude from the yoke  1411  toward the center CC. As illustrated in  FIG.  20   , the teeth  1412  may be disposed at regular intervals along an inner circumferential surface of the yoke  1411  to protrude toward the center CC. That is, the teeth  1412  may be disposed along the inner circumferential surface of the yoke  1411  to be spaced a certain distance from each other. 
     A coil  1420  may be wound around the teeth  1412 . In this case, an insulator  1430  may be disposed on the tooth  1412 . The insulator  1430  insulates the teeth  1412  and the coil  1420  from each other. 
     A current may be applied to the coil  1420 . Accordingly, electrical interaction with the magnet  1320  of the rotor  1300  may be caused to rotate the rotor  1300 . When the rotor  1300  rotates, the shaft  1500  also rotates. In this case, the shaft  1500  may be supported by the bearing  1060 . 
     The shaft  1500  may be coupled to the rotor  1300 . When electromagnetic interaction occurs between the rotor  1300  and the stator  1400  through the supply of current, the rotor  1300  rotates and the rotation shaft  1500  rotates in association with the rotor  1300 . 
     Meanwhile, the motor  1001  may further include a sensing magnet assembly  1600  to identify the position of the rotor  1300 . 
     The sensing magnet assembly  1600  may include a sensing magnet and a sensing plate. The sensing magnet and the sensing plate can be combined to have the same axis. 
     The sensing magnet may include a main magnet disposed in a circumferential direction to be adjacent to a hole forming an inner circumferential surface thereof, and a sub-magnet formed at an edge thereof. The main magnet may be arranged in the same manner as a drive magnet inserted into the rotor  1300  of the motor  1001 . The sub-magnet is subdivided to have a larger number of poles than the main magnet. Therefore, a rotation angle may be more subdivided and measured, and the motor  1001  may be more smoothly driven. 
     The sensing plate may be formed of a disc type metal material. An upper side of the sensing plate may be coupled to the sensing magnet. In addition, the sensing plate may be coupled to the shaft  1500 . Here, the sensing plate is provided with a hole through which the shaft  1500  passes. 
     In addition, the motor  1001  may further include a printed circuit board  1700  on which a sensor is disposed to sense a magnetic force of the sensing magnet. 
     In this case, the sensor may be a Hall IC. The sensor senses a change of N and S poles of the main magnet or the sub-magnet to generate a sensing signal. In the case of a three-phase brushless motor, at least three sensing signals are required to obtain information about U-, V-, and W-phases and thus at least three sensors may be arranged. 
     The printed circuit board  1700  may be coupled to a bottom surface of the bracket  1200  and installed on the sensing magnet assembly  1600  such that the sensor faces the sensing magnet. 
     Embodiments of the present invention have been described above in detail with reference to the accompanying drawings. 
     While the technical idea of the present invention has been described above with respect to examples thereof, it will be apparent to those of ordinary skill in the art that various modifications, changes and alternatives may be made without departing from the essential features of the invention. Therefore, the embodiments disclosed herein and the accompanying drawings are not intended to restrict the scope of the present invention and are only used for a better understanding of the present invention. The scope of the present invention is not limited by these embodiments and the accompanying drawings. The scope of protection of the present invention should be interpreted based on the following claims, and all technical ideas within a scope equivalent thereto should be construed as falling within the scope of the present invention. 
     DESCRIPTION OF REFERENCE NUMERALS 
       1 : electric pump,  100 : motor unit,  110 : shaft,  111 : cut surface,  120 : rotor,  130 : stator,  131 : coil,  140 : bus bar,  141 : bus bar body,  141   a : first protrusion,  143 : bus bar terminal,  143   a : connection terminal,  143   b : curved portion,  150 : motor housing,  151 : protrusion,  151   a : hole,  200 : connector unit,  210 : connector body,  211 : first through hole,  230 : connector connection part,  231 : first connection portion,  231   a : second protrusion,  231   b : rib,  231   c : groove,  233 : second connection portion,  250 : power terminal,  251 : contact portion,  300 : first cover,  310 : first surface,  320 : first suction port,  330 : first discharge port,  340 : second through hole,  400 : pump unit,  410 : first rotor,  411 : first lobe,  430 : second rotor,  431 : second lobe,  440 : third coupling hole,  500 : second cover,  510 : second surface,  520 : second suction port,  521 : inlet,  523 : third protrusion,  530 : second discharge port,  531 : outlet,  1001 : motor,  1060 : bearing,  1100 : housing,  1200 : bracket,  1300 : rotor,  1310 : rotor core,  1311 : main body,  1312 : pocket,  1313 : first barrier,  1314 : second barrier,  1315 : hole,  1320 : magnet,  1400 : stator,  1410 : stator core,  1411 : yoke,  1412 : tooth,  1420 : coil,  1500 : shaft,  1600 : sensing magnet assembly,  1700 : printed circuit board