Patent Publication Number: US-2022231550-A1

Title: Motor for vehicle

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to Japanese Patent Application No. 2021-006716 filed on Jan. 19, 2021, incorporated herein by reference in its entirety. 
     BACKGROUND 
     1. Technical Field 
     The present disclosure relates to a motor for a vehicle mounted on a vehicle. 
     2. Description of Related Art 
     For example, Japanese Unexamined Patent Application Publication No. 2017-212239 (JP 2017-212239 A) discloses an electromagnetic shield material that blocks electromagnetic waves. JP 2017-212239 A aims to reduce weight of the electromagnetic shield material. However, even when the weight of the electromagnetic shield material is reduced, for example, the electromagnetic shield material is provided in a motor, so that weight of the motor is increased by an amount of the electromagnetic shield material. 
     SUMMARY 
     The present disclosure is to obtain a motor for a vehicle capable of suppressing a magnetic field received by an occupant of a vehicle and suppressing an increase in weight. 
     A first aspect of the present disclosure relates to a motor for a vehicle including a stator, a rotor, and a protrusion portion. The stator is configured to form a magnetic field around the stator. The rotor is configured to rotate by an interaction with the magnetic field formed by the stator. The protrusion portion is formed to protrude from a part of an outer periphery of a stator body of the stator to a side of an occupant of a vehicle, of which a parameter is set based on at least one of a protrusion dimension from the stator body and a dimension along a circumferential direction of a rotation of the rotor. 
     In the motor according to the first aspect of the present disclosure, when the magnetic field is formed around the stator by the stator, the rotor rotates by the interaction with the magnetic field formed by the stator. In addition, the protrusion portion is formed to protrude from the part of the outer periphery of the stator body of the stator to the side of the occupant of the vehicle. The parameter of the protrusion portion is set based on at least one of the protrusion dimension from the stator body and the dimension along the circumferential direction of the rotation of the rotor. 
     Therefore, the increase in the weight of the motor for a vehicle can be suppressed, and the magnetic field in a specific direction to the side of the occupant can be suppressed. As described above, in the present disclosure, the magnetic field received by the occupant can be reduced without using a protective shield, such as a metal plate, so that a cost can be reduced while the increase in the weight is suppressed. 
     A second aspect of the present disclosure relates to the motor according to first aspect, in which the protrusion portion protrudes in an arc shape coaxial with the stator body. 
     In the motor according to the second aspect, an outer peripheral portion of the protrusion portion has an arc shape coaxial with the stator body, a length from a rotation center to an outer peripheral end portion of the protrusion portion is fixed. As a result, an amount of reduction in the magnetic field can be set to be fixed in the circumferential direction. 
     A third aspect of the present disclosure relates to the motor according to first or second aspect, in which a ratio of a length of the protrusion portion in the circumferential direction to a length of the stator body in the circumferential direction is smaller than a predetermined value. 
     By reducing the ratio of the length of the protrusion portion in the circumferential direction, the weight of the motor for a vehicle can be effectively reduced while an influence of the magnetic field on the occupant is reduced. 
     As described above, in the motor for a vehicle according to the aspects of the present disclosure, the magnetic field received by the occupant of the vehicle can be suppressed and the weight of the motor for a vehicle can be reduced. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Features, advantages, and technical and industrial significance of exemplary embodiments of the disclosure will be described below with reference to the accompanying drawings, in which like signs denote like elements, and wherein: 
         FIG. 1  is a schematic view of a motor for a vehicle according to an embodiment of the present disclosure as viewed from a vehicle width direction side; and 
         FIG. 2  is a graph showing a relationship between a parameter and an amount of reduction in a magnetic field (dB). 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     Hereinafter, a vehicle substructure according to an embodiment of the present disclosure will be described with reference to  FIG. 1 . Note that an arrow FR appropriately shown in  FIG. 1  indicates a front side (vehicle front side) of a vehicle to which a motor  10  for a vehicle is applied. In addition, an arrow UP indicates an upper side of the vehicle. 
     As shown in  FIG. 1 , the motor  10  for the vehicle includes a stator  12 , and the stator  12  includes a stator body  14 . In  FIG. 1 , for convenience of description, solely one stator  12  divided into eight equal parts in a circumferential direction is drawn by a solid line. The stator body  14  includes a hollow portion  16 . The hollow portion  16  has a circular cross-sectional shape orthogonal to a vehicle width direction (a depth side of a paper surface and a front side of the paper surface in  FIG. 1 ). In addition, the stator body  14  is provided with a plurality of coils  18 . By energizing the coils  18 , a magnetic field (rotation magnetic field) is formed around the stator  12 . 
     In addition, a rotor  20  is included inside the hollow portion  16  of the stator body  14 . The rotor  20  includes a plurality of permanent magnets  22 . The permanent magnets  22  form a magnetic field around the rotor  20 . The rotor  20  rotates around an axis with the vehicle width direction as an axial direction by an interaction between the magnetic field (rotation magnetic field) formed around the stator  12  by energizing the coils  18  of the stator body  14  and the magnetic field formed around the rotor  20  by the permanent magnets  22  of the rotor  20 . 
     In addition, a protrusion portion  24  is formed from an outer peripheral portion of the stator body  14  of the stator  12  on a side of an occupant of the vehicle. In a case where an outer peripheral shape of the stator body  14  is regarded as a circle, the protrusion portion  24  protrudes in an arc shape coaxial with the outer peripheral portion of the stator body  14 . 
     Here, in a graph of  FIG. 2 , an amount of reduction in the magnetic field in a case where the magnetic field is observed from the side of the occupant of the vehicle with respect to the protrusion portion  24  is shown by a decibel (dB). For example, in a line described as  4  in  FIG. 2 , the amount of reduction in the magnetic field of  4  dB can be obtained. In addition, a vertical axis A of  FIG. 2  is a value (%) obtained by the following expression (1). 
         A= ( R−a )·100/ R    (1)
 
     Here, R is a distance from a rotation center C of the rotor  20  to an outer peripheral end portion of the protrusion portion  24 . In addition, a is an amount of protrusion of the protrusion portion  24  from the outer peripheral portion of the stator body  14  of the stator  12 . 
     On the other hand, a horizontal axis B in  FIG. 2  is a value (%) obtained by the following expression (2). 
         B=· 100/(2 πR· 1/8)   (2)
 
     Here, since b is a length of the protrusion portion  24  in the circumferential direction of the rotation of the rotor  20 , B is a ratio of a length of b in the circumferential direction with respect to an arc length obtained by dividing the length of the stator body  14  in the circumferential direction by one-eighth. 
     As can be seen from  FIG. 2 , by reducing a ratio of B, the length of the protrusion portion  24  in the circumferential direction of the rotation of the rotor  20  is reduced. Therefore, an amount of reduction in weight of the stator  12  is larger than that in a case where a ratio of A is reduced. As an example, a dimension of the protrusion portion  24  shown in  FIG. 1  is set to about 98.5% for A and about 45% for B. 
     Here, when A and B are set to be within a range surrounded by a chain line in  FIG. 2 , weight of the motor  10  for the vehicle can be effectively reduced while an influence of the magnetic field is reduced. That is, in the range, since an interval between the amount of reduction in the magnetic fields  3  and  4  is wide, the amount of reduction in the magnetic field is not significantly changed even in a case where the ratio of B is reduced. Therefore, the weight of the motor  10  for the vehicle can be effectively reduced while the influence of the magnetic field on the occupant is reduced. 
     Therefore, by reducing the ratio of B as much as possible and defining, based on  FIG. 2 , a structure of the protrusion portion  24 , such as the amount of protrusion of the protrusion portion  24  from the outer peripheral portion of the stator body  14  within a range in which the magnetic field can be efficiently reduced, the weight of the motor  10  for the vehicle can be reduced, and the magnetic field emitted by the motor  10  for the vehicle to the outside on the side of the occupant of the vehicle can be effectively reduced. 
     In addition, as shown in  FIG. 1 , by forming the protrusion portion  24  into the arc shape coaxial with the outer peripheral portion of the stator body  14 , the length from the rotation center C to the outer peripheral end portion of the protrusion portion  24  is fixed. As a result, the amount of reduction in the magnetic field can be set to be fixed in the circumferential direction. 
     Note that in the present embodiment, both A and B are used, but solely any one of A and B may be used, any one of A and B and at least the other one of A and B may be used, or at least one other than A and B may be used.