Patent Publication Number: US-11658552-B2

Title: Motor, and motor-driven steering apparatus having same

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a Continuation of U.S. application Ser. No. 16/068,036, filed on Jul. 3, 2018, which is the National Phase of PCT International Application No. PCT/KR2016/012798, filed on Nov. 8, 2016, which claims priority under 35 U.S.C. 119(a) to Patent Application No. 10-2016-0002224, filed in the Republic of Korea on Jan. 7, 2016, all of which are hereby expressly incorporated by reference into the present application. 
    
    
     TECHNICAL FIELD 
     The present invention relates to a motor and a motor-driven steering apparatus including the same 
     BACKGROUND OF THE INVENTION 
     Generally, a rotor is rotated due to an electromagnetic interaction between the rotor and a stator in a motor. Here, since a rotational shaft inserted into the rotor is also rotated, a rotational driving force is generated. 
     A sensor including a magnetic element is disposed inside the motor as a rotor position detecting apparatus. The sensor grasps a present position of the rotor by detecting a magnetic force of the sensing magnet installed to be rotatable in conjunction with the rotor. 
     The sensor may include a plurality of magnetic elements. Here, in addition to three magnetic elements for feedback on U-phase, V-phase, and W-phase information, two magnetic elements for grasping a rotation direction of the motor and a more precise rotation angle are additionally installed in the sensor. The two magnetic elements are disposed to be spaced a predetermined distance from each other in a circumferential direction of the sensing magnet. Accordingly, sensing signals detected by the two magnetic elements have a phase difference, and thus the rotation direction of the motor and the rotation angle are more precisely grasped. 
     Since the magnetic elements may be mounted on a printed circuit board and disposed in a housing of the motor and have a structure vulnerable to electromagnetic interference (EMI), there is a high possibility of EMI failure during an EMI test. 
     Accordingly, there is a problem in that there is a high possibility of failure of the magnetic element during an electrostatic discharge (ESD) test. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to providing a motor, in which a ground pattern corresponding to a Hall integrated circuit (IC) is formed on a substrate to reduce a possibility of failure due to electromagnetic interference (EMI) or static electricity, and a motor-driven steering apparatus including the same. 
     Objectives to be achieved by the embodiments of the present invention are not limited to the above-described objectives, and other objectives, which are not described above, may be clearly understood by those skilled in the art through the following specification. 
     One aspect of the present invention provides a motor including: a housing in which an opening is formed at one side thereof and an accommodation space is formed; a bracket disposed to cover the opening of the housing; a stator disposed in the accommodation space; a rotor disposed in the stator; a shaft coupled to the rotor; a sensing magnet assembly disposed above the rotor; and a rotor position detecting apparatus configured to detect a change in magnetic flux of the sensing magnet assembly, wherein the rotor position detecting apparatus includes a substrate, a Hall signal magnetic element mounted on the substrate, an encoder signal magnetic element mounted on the substrate, and a first ground pattern formed on the substrate, and the first ground pattern is electrically connected to the Hall signal magnetic element. 
     The first ground pattern may be disposed at an inner side of the substrate with respect to a virtual line (C) passing through a center in a circumferential direction of the substrate. 
     The motor may further include a second ground pattern electrically connected to the encoder signal magnetic element and formed at an outer edge of the substrate with respect to the virtual line (C) passing through the center in the circumferential direction of the substrate. 
     The bracket may include: a bracket main body; a coupling hole which is formed in a center of the bracket main body and in which the shaft is disposed; a seating portion concavely formed around the coupling hole toward the rotor; and a coupling part formed to protrude from a lower surface of the bracket main body. 
     The second ground pattern may be fixedly in contact with one side of the coupling part by a fixing member. 
     The second ground pattern may be in contact with the coupling part by the fixing member, and the first ground pattern may be in contact with one side of the seating portion. 
     The sensing magnet assembly may include: a sensing plate; and a sensing magnet seated on the sensing plate, wherein the sensing plate may be coupled to the shaft so as to rotate. 
     The sensing magnet may include: a main magnet disposed at a center of the sensing plate; and a sub-magnet disposed at an edge of the sensing plate, wherein the Hall signal magnetic element may detect a change in magnetic flux of the main magnet, and the encoder signal magnetic element may detect a change in magnetic flux of the sub-magnet. 
     With respect to a virtual line (C) passing through the center in the circumferential direction of the substrate, the Hall signal magnetic element may be disposed at an inner side of the substrate, and the encoder signal magnetic element may be disposed at an outer side of the substrate. 
     The main magnet may include a plurality of split magnets, and the number of the split magnets may be the same as that of magnets of the rotor. 
     Another aspect of the present invention provides a motor-driven steering apparatus including: a steering shaft; and a motor connected to the steering shaft, wherein the motor includes the above-described motor. 
     Advantageous Effects 
     A rotor position detecting apparatus according to the embodiment including the above-described structure can reduce a possibility of electromagnetic interference (EMI) failure of a motor due to a Hall integrated circuit (IC). 
     In addition, the rotor position detecting apparatus can reduce a possibility of electrostatic failure of the motor. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a perspective view illustrating a motor according to an embodiment. 
         FIG.  2    is an exploded perspective view illustrating the motor according to the embodiment. 
         FIG.  3    is a cross-sectional view illustrating the motor according to the embodiment, taken along line A-A of  FIG.  1   . 
         FIG.  4    is a perspective view illustrating a bracket of the motor according to the embodiment. 
         FIG.  5    is a bottom perspective view illustrating the bracket of the motor according to the embodiment. 
         FIG.  6    is a view illustrating a sensing magnet assembly of the motor according to the embodiment. 
         FIG.  7    is a view illustrating a rotor position detecting apparatus of the motor according to the embodiment. 
         FIG.  8    is a view showing improved electromagnetic interference (EMI) of the motor according to the embodiment when compared with a reference example. 
         FIG.  9    is a view illustrating a motor-driven steering apparatus according to an embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     While the invention can be modified in various ways and take on various alternative forms, specific embodiments thereof are shown in the drawings and described in detail below as examples. However, it should be understood that there is no intent to limit the invention to the particular forms disclosed, but on the contrary, the invention covers all modifications, equivalents, and alternatives falling within the spirit and scope of the present invention. 
     It will be understood that, although the terms “first,” “second,” etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be called a second element, and a second element could similarly be called a first element without departing from the scope of the present invention. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. 
     It will be understood that when an element is referred to as being “connected” or “coupled” to another element, it can be directly connected or coupled to the other element or intervening elements may be present. In contrast, when an element is referred to as being “directly connected” or “directly coupled” to another element, there are no intervening elements. 
     In a description of the embodiments, in a case in which any one element is described as being formed on (or under) another element, such a description includes both a case in which the two elements are formed to be in direct contact with each other and a case in which the two elements are in indirect contact with each other such that one or more other elements are interposed between the two elements. In addition, when in a case in which one element is described as being formed on (or under) the other element, such a description may include a case in which one element is formed at an upper side or a lower side with respect to the other element. 
     The terminology used herein to describe embodiments of the invention is not intended to limit the scope of the invention. The articles “a,” and “an” are singular in that they have a single referent, however, the use of the singular form in the present document should not preclude the presence of more than one referent. In other words, elements of the invention referred to in the singular may number one or more, unless the context clearly indicates otherwise. It will be further understood that the terms “comprise,” “comprising,” “include,” and/or “including,” when used herein, specify the presence of stated features, numbers, steps, operations, elements, components, and/or combinations thereof, but do not preclude the presence or addition of one or more other features, numbers, steps, operations, elements, components, and/or combinations thereof. 
     Unless otherwise defined, all terms (including technical and scientific terms) used herein are to be interpreted as is customary in the art to which this invention belongs. It will be further understood that terms in common usage should also be interpreted as is customary in the relevant art and not in an idealized or overly formal sense unless expressly so defined herein. 
     Hereinafter, exemplary embodiments of the invention will be described in detail with reference to the accompanying drawings. The same or corresponding elements will be consistently denoted by the same respective reference numerals and described in detail no more than once regardless of drawing symbols. 
     In a motor according to an embodiment of the present invention, a ground pattern corresponding to a Hall integrated circuit (IC) is formed on a substrate to reduce a possibility of failure due to electromagnetic interference (EMI) or static electricity. 
     Referring to  FIGS.  1  to  9   , a motor  1  according to the embodiment of the present invention may include a housing  100 , a bracket  200 , a stator  300  disposed inside the housing  100 , a rotor  400  rotatably disposed in the stator  300 , a shaft  500  inserted into the rotor  400  by passing therethrough and rotated in conjunction with the rotor  400 , a bearing  600 , a sensing magnet assembly  700 , a rotor position detecting apparatus  800 , and a busbar  900 . 
     In addition, the motor  1  may further include a lower bearing  610  disposed to support rotation of the shaft  500 , a coupler  620  disposed at an end of one side of the shaft  500 , a busbar power line  910 , and the like. 
     The housing  100  may be formed in a cylindrical shape. In addition, an accommodation space S in which the stator  300 , the rotor  400 , and the busbar  900  may be installed is provided in the housing  100 . 
     As illustrated in  FIG.  1   , the housing  100  may be formed in the cylindrical shape and may include an opening formed at one side of the housing  100  and the accommodation space S formed to communicate with the opening. Here, a shape or material of the housing  100  may be variously changed, but the housing  100  may be formed of a metal material which can withstand high temperatures well. 
     The housing  100  is coupled to the bracket  200  disposed to cover the opening to shield the stator  300  and the rotor  400  from the outside. In addition, the housing  100  may further include a cooling structure (not shown) to easily discharge internal heat. The cooling structure may include an air- or water-cooling structure, and the shape of the housing  100  may be suitably changed according to the cooling structure. 
     Referring to  FIGS.  4  and  5   , the bracket  200  may include a bracket main body  210  having a plate shape, a coupling hole  220  formed at a center of the bracket main body  210 , a seating portion  230  formed in a concave shape around the coupling hole  220 , and a coupling part  240 . 
     The bracket main body  210  may be disposed to cover the opening of the housing  100 . 
     As illustrated in  FIG.  4   , the seating portion  230  may be formed in the concave shape from an upper surface  211  of the bracket main body  210  at a center of the bracket main body  210  toward the rotor  400 . In addition, the coupling hole  220  may be formed at a center of the seating portion  230  such that the shaft  500  is disposed. 
     Accordingly, the bearing  600  may be disposed on a seating surface  231  of the seating portion  230  to rotatably support the shaft  500 . 
     As illustrated in  FIG.  5   , the coupling part  240  may be formed to protrude from a lower surface  212  of the bracket main body  210 . Here, the coupling part  240  may be disposed to be spaced apart from the seating portion  230 . 
     In addition, the coupling part  240  may be fixedly in contract with one side of the rotor position detecting apparatus  800  by a fixing member  10  such as a bolt, a screw, or the like. More specifically, a second ground pattern  850  of the rotor position detecting apparatus  800  may be fixedly in contact with a contact surface  241  of the coupling part  240  by the fixing member  10 . 
     In addition, as the second ground pattern  850  is fixedly in contact with the contact surface  241  of the coupling part  240  by the fixing member  10 , a first ground pattern  840  may be disposed to be in close contact with a contact surface  232  of the seating portion  230 . 
     The stator  300  is inserted into the accommodation space S of the housing  100 . The stator  300  may include stator cores  310  and coils  320  wound around the stator core  310 . The stator core  310  may be an integrated core formed in a ring shape or may also be a core in which a plurality of separated cores are combined. 
     The stator  300  may be suitably changed according to a type of the motor. For example, the stator  300  may be manufactured such that, in the case of a direct current (DC) motor, a coil may be wound around an integrated stator core, and in the case of a three-phase control motor, the U-phase, V-phase, and W-phase are respectively input to a plurality of coils. 
     The busbar  900  may be disposed above the stator  300 , and the coils  320  of the stator  300  may be connected to the busbar  900 . Here, a plurality of metal members (terminals) electrically connected to the coils  320  may be insulated by an insulator and fixedly disposed on the busbar  900 . 
     The rotor  400  may be rotatably disposed in the stator  300 . A magnet is disposed at the rotor  400 , and electromagnetically interacts with the stator  300  to rotate the rotor  400 . 
     The shaft  500  is coupled to a central portion of the rotor  400 . Accordingly, when the rotor  400  rotates, the shaft  500  also rotates. Here, the shaft  500  may be rotatably supported by the bearing  600 . 
     The shaft  500  is coupled to an external apparatus to provide power to the external apparatus. As an example, in a case in which the motor  1  is used as an electric power steering (EPS) motor, the shaft  500  may be connected to a vehicle steering shaft to provide assistant steering power to the vehicle steering shaft. 
     The rotor position detecting apparatus  800  according to one embodiment of the present invention detects a change in magnetic flux in the sensing magnet assembly  700  rotated in conjunction with the shaft  500  to detect a rotational position of the rotor  400 . 
     Referring to  FIG.  6   , the sensing magnet assembly  700  may include a sensing plate  710  and a sensing magnet  720  seated on the sensing plate  710 . The sensing plate  710  may be coupled to the shaft  500  so as to be rotatable. 
     The sensing magnet  720  may be formed in a circular disk shape and may include a main magnet  711  disposed at a central portion of the sensing plate  710 , a sub-magnet  712  disposed at an edge of the sensing plate  710 . The main magnet  711  includes a plurality of split magnets formed in a split ring shape. The number of the split magnets (poles) of the main magnet  711  is the same as the number of the rotor magnets (poles) so that the rotation of the rotor may be detected. 
     The sub-magnet  712  is disposed at the edge of the circular disk, and includes a number of split magnets (poles) larger than the main magnet  711 . Accordingly, one pole (split magnet) of the main magnet  711  is disassembled by further subdivision. Accordingly, an amount of rotation may be more precisely measured. Here, in the sub-magnet  712 , an N-pole split magnet and a S-pole split magnet may be alternately disposed. 
     Referring to  FIG.  7   , the rotor position detecting apparatus  800  may include a substrate  810 , a plurality of Hall signal magnetic elements  820  disposed to be spaced a predetermined distance from each other on the substrate  810 , a plurality of encoder signal magnetic elements  830  disposed to be spaced a predetermined distance from each other on the substrate  810 , the first ground pattern  840  electrically connected to the Hall signal magnetic elements  820 , the second ground pattern  850  electrically connected to the encoder signal magnetic elements  830 , and fixing holes  860 . 
     The magnetic elements  820  and  830  may be disposed on the substrate  810  to be spaced apart from the sensing magnet assembly  700  and may calculate a rotation angle according to a change in magnetic flux. Here, the magnetic elements  820  and  830  may be a Hall IC, and Vccs and grounds GND of the magnetic elements  820  and  830  may be separated from each other as illustrated in  FIG.  7   . 
     Referring to  FIG.  7   , the substrate  810  may be formed as a plate having an arc shape. In addition, the Hall signal magnetic elements  820  and the first ground pattern  840  may be disposed at an inner side of the substrate  810  with reference to a virtual line C drawn in a circumferential direction at a center of the substrate  810 . 
     Here, the term ‘outer side’ refers to an outer side with respect to the virtual line C in a radial direction from a rotational center of the shaft  500 , and the term ‘inner side’ refers to an inner side with respect to the virtual line C in the radial direction from the rotational center of the shaft  500 . 
     The first ground pattern  840  may be formed in an arc shape and disposed at an inner edge of the substrate  810 . In addition, the first ground pattern  840  may be electrically connected to the ground GND of the Hall signal magnetic element  820 . 
     In addition, the first ground pattern  840  may be disposed to be in close contact with one side of the bracket  200 . For example, the first ground pattern  840  may be disposed to be in close contact with the contact surface  232  located at a side opposite the seating surface  231  of the bracket  200 . 
     Accordingly, an area of the ground GND of the Hall signal magnetic element  820  increases relatively, and accordingly, a possibility of EMI or electrostatic failure of the motor  1  due to the Hall signal magnetic element  820  may decrease. 
     Meanwhile, the encoder signal magnetic elements  830  and the second ground pattern  850  may be disposed at the outer side of the substrate  810  with respect to the virtual line C drawn in the circumferential direction of the substrate  810 . 
     Here, the second ground pattern  850  may be formed in an arc shape and disposed at an outer edge of the substrate  810 . In addition, the second ground pattern  850  may be electrically connected to the ground GND of the encoder signal magnetic element  830 . 
     In addition, the second ground pattern  850  may be disposed to be in close contact with the coupling part  240  of the bracket  200 . That is, the second ground pattern  850  may be fixedly disposed to be in close contact with the coupling part  240  by the fixing member  10  disposed to pass through the fixing hole  860 . 
     In addition, as an end portion of the fixing member  10  is coupled to the coupling part  240 , the first ground pattern  840  may also be disposed to be in close contact with the contact surface  232 . 
       FIG.  8    is a view showing improved EMI of the motor according to one embodiment of the present invention. That is,  FIG.  8 A  is a view illustrating the rotor position detecting apparatus  800  from which the first ground pattern  840  is removed (reference example), and  FIG.  8 B  is a comparison graph between EMI of the reference example and improved EMI of the motor  1 . 
     As illustrated in  FIG.  8 B , EMI of the motor  1  is improved by about 160% due to the first ground pattern  840 , compared to the reference example. 
     Hereinafter, an operation of detecting a position of the rotor  400  using the rotor position detecting apparatus  800  and the sensing magnet assembly  700  will be described. 
     The rotor position detecting apparatus  800  may include a plurality of magnetic elements  820  and  830  configured to detect a change in magnetic flux according to rotation of the sensing magnet assembly  700  to detect a position of the rotor  400 . 
     Since the main magnet  711  of the sensing magnet assembly  700  is provided to correspond to the magnet of the rotor  400 , a change in magnet flux of the main magnet  711  has to be detected to detect a position of the rotor  400 . 
     The rotor position detecting apparatus  800  may detect a change in magnetic flux of the main magnet  711  through the Hall signal magnetic element  820  to detect three sensing signals. In addition, the rotor position detecting apparatus  800  may detect a change in magnetic flux of the sub-magnet  712  through the encoder signal magnetic element  830  to detect two sensing signals. Here, a rotation direction and a precise rotation angle of the motor may be calculated using the two sensing signals. 
     Meanwhile, a motor-driven steering apparatus (or electric power steering (EPS))  2  according to an embodiment of the present invention may include the motor  1 . 
     Referring to  FIG.  9   , the motor-driven steering apparatus  2  may include the motor  1 , a steering wheel  3 , a steering shaft  4 , a steering angle sensor  5 , and an electronic control unit (ECU)  6 . 
     The steering wheel  3  is generally called as a handle, and a driver rotates the steering wheel  3  to change a direction of a vehicle. The steering wheel  3  may be disposed to be connected to the steering shaft  4 , and when the driver rotates the steering wheel  3 , the steering shaft  4  is rotated in conjunction with the rotation of the steering wheel  3  in a direction the same as that of the steering wheel  3 . 
     The motor  1  is a motor configured to assist a torque for the driver to manipulate the steering wheel  3  to steer and assists the driver to more easily steer the vehicle. 
     A reduction apparatus and a torque sensor (not shown) may be coupled to one end of the motor  1 . The torque sensor detects a relative rotational displacement between an input shaft and an output shaft according to rotation of the steering wheel  3 , generates an electric signal, and transmits the electric signal to the ECU  6 . 
     The steering angle sensor  5  is installed near the steering wheel  3 , and directly measures a rotation angle of the steering wheel  3  rotated by manipulation of the driver. In addition, the steering angle sensor  5  transmits a signal related to the measured rotation angle to the ECU  6 . 
     The ECU  6  may electronically control various driving sources of the motor-driven steering apparatus including the motor  1  on the basis of information of a vehicle speed sensor, which is not shown, and the torque sensor and the steering angle sensor  5 . 
     Here, the motor  1  may be connected to the steering shaft of the motor-driven steering apparatus  2 . 
     While the present invention has been described with reference to exemplary embodiments, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the present invention as defined by the appended claims. In addition, it will be interpreted that differences related to the changes and modifications fall within the scope of the present invention defined by the appended claims.