Patent Publication Number: US-2022231563-A1

Title: Stator and motor

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application claims priority under 35 U.S.C. § 119 to Japanese Patent Application No. 2021-006981, filed on Jan. 20, 2021, the entire contents of which are hereby incorporated herein by reference. 
     1. FIELD OF THE INVENTION 
     The present disclosure relates to a stator used in a stepping motor. 
     2. BACKGROUND 
     Conventionally, a stepping motor includes a motor called a claw-pole motor. The claw-pole motor has a stator. The stator includes a stator core. The stator core has a plurality of claw-shaped pole teeth (claw poles) arranged in the circumferential direction. 
     The stator in the claw-pole motor as described above includes a coil arranged between a pair of the stator cores. In a case where the motor is of an outer rotor type, when a lead wire from a coil is provided outside the stator, the lead wire may have come into contact with the rotor. 
     SUMMARY 
     A stator according to an example embodiment of the present disclosure includes a cylindrical shaft extending in an axial direction, annular portions positioned side by side in the axial direction radially outside the shaft and extending in a radial direction, pole teeth extending in the axial direction from a radially outer end portion of each of the annular portions, and one or more coils between the annular portions adjacent to each other in the axial direction and wound around the shaft. 
     The shaft includes one or more slits recessed radially inward from an outer peripheral surface of the shaft and extending along the axial direction. 
     A portion of the slit is radially inside the annular portion. 
     A lead wire of the coil is in the slit. 
     The above and other elements, features, steps, characteristics and advantages of the present disclosure will become more apparent from the following detailed description of the example embodiments with reference to the attached drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a longitudinal cross-sectional view of a motor according to an example embodiment of the present disclosure. 
         FIG. 2  is a perspective view of a stator according to an example embodiment of the present disclosure. 
         FIG. 3  is a perspective view illustrating a sleeve and a lead wire according to an example embodiment of the present disclosure. 
         FIG. 4  is an enlarged perspective view illustrating a configuration in the vicinity of a disk portion  12 B in  FIG. 3 . 
         FIG. 5  is a perspective view of  FIG. 3  as viewed from a different direction. 
         FIG. 6  is a perspective view of a partial configuration of the stator according to a variation of an example embodiment of the present disclosure as viewed from a second side in an axial direction. 
         FIG. 7  is a longitudinal cross-sectional view of the motor having the stator according to a variation of an example embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Example embodiments of the present disclosure will be described with reference to the drawings. 
     In the present description, in a motor  10 , the direction parallel to a central axis J of the motor  10  is referred to as the “axial direction”. Note that, in the drawings, the “first side in the axial direction” is denoted by X 1  and the “second side in the axial direction” is denoted by X 2 . Further, in the motor  10 , the direction around the central axis J is referred to as the “circumferential direction”. In the motor  10 , the radial direction with respect to the central axis J is simply referred to as the “radial direction”, the direction approaching the central axis J is referred to as the “radially inward”, and the direction away from the central axis J is referred to as the “radially outward”. 
     Since a central axis of a stator S described later coincides with the central axis J of the motor  10 , reference to directions for the stator S is the same as the above. 
       FIG. 1  is a longitudinal cross-sectional view of the motor  10  according to an example embodiment of the present disclosure. 
     The motor  10  is a claw-pole stepping motor and also is an outer rotor motor. The motor  10  includes the stator S, bearings  7 A and  7 B, and a rotor  8 . The rotor  8  is arranged radially outside the stator S. 
     The stator S includes a sleeve  1 , stator cores  2 ,  3 ,  4 , and  5 , and coils  61  and  62 . The sleeve  1  is a member extending in the axial direction and is made from a magnetic material. The stator core  2  is fixed to the first side in the axial direction of the sleeve  1 . The stator cores  3  and  4  are adjacent to each other in contact with each other in the axial direction, and are fixed to the middle in the axial direction of the sleeve  1 . The stator core  5  is fixed to the second side in the axial direction of the sleeve  1 . 
     The stator core  2  has a plurality of pole teeth arranged in the circumferential direction and extending to the second side in the axial direction. The stator core  3  has a plurality of pole teeth arranged in the circumferential direction and extending to the first side in the axial direction. The stator core  4  has a plurality of pole teeth arranged in the circumferential direction and extending to the second side in the axial direction. The stator core  5  has a plurality of pole teeth arranged in the circumferential direction and extending to the first side in the axial direction. 
     The coils  61  and  62  are formed in a manner that a conductive wire is wound around the outer periphery of the sleeve  1  and are arranged in the axial direction. The coil  61  is arranged on the first side in the axial direction of the coil  62 . The coil  61  faces the pole teeth in the radial direction radially inside the pole teeth of the stator cores  2  and  3 . The coil  62  faces the pole teeth in the radial direction radially inside the pole teeth of the stator cores  4  and  5 . 
     The bearing  7 A is fixed to the outer periphery of an end portion on the first side in the axial direction of the sleeve  1 . The bearing  7 A is a ball bearing. The bearing  7 B is fixed to the outer periphery of an end portion on the second side in the axial direction of the sleeve  1 . The bearing  7 B is a ball bearing. 
     The rotor  8  has a housing  81  and a magnet  82 . The housing  81  has a cylindrical shape extending in the axial direction about the central axis J. An end portion on the first side in the axial direction of an inner peripheral surface of the housing  81  is fixed to an outer peripheral surface of the bearing  7 A. An end portion on the second side in the axial direction of the inner peripheral surface of the housing  81  is fixed to an outer peripheral surface of the bearing  7 B. 
     The magnet  82  has a cylindrical shape extending in the axial direction about the central axis J. The magnet  82  is a permanent magnet, and is composed of, for example, a ferrite magnet. The magnet  82  is fixed to a radially inner peripheral surface of the housing  81 . The magnet  82  is arranged between the bearing  7 A and the bearing  7 B in the axial direction. The magnet  82  radially faces the stator cores  2 ,  3 ,  4 , and  5  in the radial direction radially outside the stator cores  2 ,  3 ,  4 , and  5 . 
     As illustrated in  FIG. 2  described later, pole teeth  22  of the stator core  2  and pole teeth  32  of the stator core  3  are alternately arranged in the circumferential direction as viewed in the axial direction. Further, pole teeth  42  of the stator core  4  and pole teeth  52  of the stator core  5  are alternately arranged in the circumferential direction as viewed in the axial direction. As the coils  61  and  62  are energized, in each of a pair of the stator cores  2  and  3  and a pair of the stator cores  4  and  5 , a plurality of pole teeth arranged in the circumferential direction as viewed in the axial direction are alternately magnetized in the circumferential direction with the N pole and the S pole. The rotor  8  rotates in the circumferential direction by the action of the pole teeth magnetized in this way and the magnet  82 . 
     The configuration of the stator S will be described in detail. Here, reference is made to  FIG. 2  in addition to  FIG. 1 .  FIG. 2  is a perspective view of the stator S. 
     The sleeve  1  includes a shaft  11  and disk portions  12 A,  12 B, and  12 C. The shaft  11  and the disk portions  12 A,  12 B, and  12 C constitute the sleeve  1  which is the same member. That is, the sleeve  1  is formed by integral molding. 
     The shaft  11  has a columnar shape extending in the axial direction. Each of the disk portions  12 A,  12 B, and  12 C is formed to extend radially outward from the outer periphery of the shaft  11 . The disk portions  12 A,  12 B, and  12 C are arranged side by side in the axial direction. 
     The stator core  2  includes an annular core portion  21  having an annular shape and a plurality of the pole teeth  22 . The pole teeth  22  extend from an end on the second side in the axial direction of the annular core portion  21  toward the other side in the axial direction. The annular core portion  21  is fixed to the outer periphery of the disk portion  12 A. The disk portion  12 A and the annular core portion  21  constitute an annular portion R 1  ( FIG. 2 ). 
     The stator core  3  includes an annular core portion  31  having an annular shape and a plurality of the pole teeth  32 . The pole teeth  32  extend from an end on the first side in the axial direction of the annular core portion  31  toward the one side in the axial direction. The annular core portion  31  is fixed to the outer periphery of the disk portion  12 B. 
     The stator core  4  includes an annular core portion  41  having an annular shape and a plurality of the pole teeth  42 . The pole teeth  42  extend from an end on the second side in the axial direction of the annular core portion  41  toward the other side in the axial direction. The annular core portion  41  is fixed to the outer periphery of the disk portion  12 B on the second side in the axial direction of the annular core portion  31 . The annular core portion  31  and the annular core portion  41  are in contact with each other in the axial direction. 
     The disk portion  12 B, the annular core portion  31 , and the annular core portion  41  constitute an annular portion R 2  ( FIG. 2 ). 
     The stator core  5  includes an annular core portion  51  having an annular shape and a plurality of the pole teeth  52 . The pole teeth  52  extend from an end on the first side in the axial direction of the annular core portion  51  toward the one side in the axial direction. The annular core portion  51  is fixed to the outer periphery of the disk portion  12 C. The disk portion  12 C and the annular core portion  51  constitute an annular portion R 3  ( FIG. 2 ). 
     That is, the stator S has a plurality of the annular portions R 1 , R 2 , and R 3  arranged side by side in the axial direction radially outside the shaft  11  and expanding in the radial direction. Further, the stator S has a plurality of the pole teeth  22 ,  32 ,  42 , and  52  extending in the axial direction from a radially outer end portion of a plurality of the annular portions R 1 , R 2 , and R 3 . 
     The coil  61  is arranged between the disk portion  12 A and the disk portion  12 B in the axial direction, and is wound around the outer periphery of the shaft  11 . The coil  62  is arranged between the disk portion  12 B and the disk portion  12 C in the axial direction, and is wound around the outer periphery of the shaft  11 . 
     That is, the stator S includes one or more of the coils  61  and  62  arranged between the annular portions R 1 , R 2 , and R 3  adjacent to each other in the axial direction and wound around the shaft  11 . 
     The shaft  11  is provided with a slit as described below, and a configuration related to the slit will be described in detail here. 
       FIG. 3  is a perspective view mainly illustrating the sleeve  1  and lead wires  611  and  621 . As illustrated in  FIG. 3 , the shaft  11  is provided with a slit  111  that is recessed radially inward from an outer peripheral surface of the shaft  11  and extends along the axial direction. The slit  111  extends from a position on the first side in the axial direction of the disk portion  12 B to an end on the second side in the axial direction of the shaft  11 . 
       FIG. 4  is an enlarged perspective view mainly illustrating a configuration in the vicinity of the disk portion  12 B in  FIG. 3 . As illustrated in  FIGS. 3 and 4 , the disk portion  12 B has a notch portion  121 B notched in the radial direction from an outer peripheral surface to an inner peripheral surface of the disk portion  12 B. A part of the slit  111  is arranged radially inside the notch portion  121 B. 
     Similarly, the disk portion  12 C has a notch portion  121 C notched in the radial direction from an outer peripheral surface to an inner peripheral surface of the disk portion  12 C ( FIG. 3 ). A part of the slit  111  is arranged radially inside the notch portion  121 C. 
     In this manner, at the time the stator S is manufactured, after the coil  61  is formed, the lead wire  611  drawn out from the coil  61  can be caused to pass through the notch portions  121 B and  121 C from the radially outside to the radially inside so as to be accommodated in the slit  111 . Note that two of the lead wires  611  are also accommodated in the slit  111 . 
       FIG. 5  is a perspective view of  FIG. 3  as viewed from a different direction. As illustrated in  FIG. 5 , the shaft  11  is provided with a slit  112  that is recessed radially inward from an outer peripheral surface of the shaft  11  and extends along the axial direction. The slit  112  is at a circumferential position different from that of the slit  111 . The slit  112  extends from a position slightly closer to the first side in the axial direction of the disk portion  12 C to an end on the second side in the axial direction of the shaft  11 . 
     The disk portion  12 C has a notch portion  122 C notched in the radial direction from an outer peripheral surface to an inner peripheral surface of the disk portion  12 C. The notch portion  122 C is at a circumferential position different from that of the notch portion  121 C. A part of the slit  112  is arranged radially inside the notch portion  122 C. 
     In this manner, at the time the stator S is manufactured, after the coil  62  is formed, the lead wire  621  drawn out from the coil  62  can be caused to pass through the notch portion  122 C from the radially outside to the radially inside so as to be accommodated in the slit  112 . Note that two of the lead wires  621  are also accommodated in the slit  112 . 
     As described above, in the present example embodiment, the shaft  11  has one or more of the slits  111  and  112  that are recessed radially inward from the outer peripheral surface of the shaft  11  and extend along the axial direction. A part of the slit  111  and  112  is arranged radially inside the annular portions R 2  and R 3 . The lead wires  611  and  621  of the coils  61  and  62  are accommodated in the slits  111  and  112 . 
     According to this, even in a case where the annular portions R 2  and R 3  supporting the pole teeth  32 ,  42 , and  52  are provided, the lead wires  611  and  621  of the coils  61  and  62  can be accommodated in the slits  111  and  112  while being arranged radially inside the annular portions R 2  and R 3  without detouring around the radially outside of the annular portions R 2  and R 3 . Therefore, it is not necessary to provide the lead wires  611  and  621  outside the stator S, and it is possible to suppress the contact of the lead wires  611  and  621  with the rotor  8  arranged radially outside the stator S. 
     The disk portions  12 B and  12 C can also be regarded as an inner annular portion which is a part of the radially inner side of the annular portions R 2  and R 3 . In this case, the inner annular portion has the notch portions  121 B,  121 C, and  122 C extending from a radially outer end to a radially inner end of the inner annular portion. The radially inner ends of the notch portions  121 B,  121 C, and  122 C overlap a part of the slits  111  and  112  in the circumferential direction. 
     In this manner, even in a case where the inner annular portion ( 12 B and  12 C) and the shaft  11  constitute the same member in order to improve assembly workability, the lead wires  611  and  621  can be accommodated in the slits  111  and  112  via the notch portions  121 B,  121 C, and  122 C, so that wiring workability is improved. 
     As illustrated in the configuration of the notch portion  121 B in  FIG. 4 , the circumferential widths of the notch portions  121 B,  121 C, and  122 C decrease from radially outer ends toward radially inner ends of the notch portions  121 B,  121 C, and  122 C. By the above configuration, the lead wires  611  and  621  can be easily inserted into the notch portions  121 B,  121 C, and  122 C. 
     One or more of the coils  61  and  62  are a plurality of coils. One or more of the slits  111  and  112  are a plurality of slits. Circumferential positions of a plurality of the slits  111  and  112  are different from each other. In this manner, since the lead wires  611  and  621  of a plurality of the coils  61  and  62  can be accommodated in the separate slits  111  and  112 , wiring workability can be improved. That is, the workability is improved as compared with the work of accommodating four in total of the lead wires  611  and  621  in one slit. 
     As illustrated in  FIGS. 3 and 5 , the slits  111  and  112  have slit portions  111 A and  112 A extending between an end portion on the second side in the axial direction of the coils  61  and  62  from which the lead wires  611  and  621  are drawn out and the disk portions  12 B and  12 C. That is, the slits  111  and  112  have the slit portions  111 A and  112 A extending between axial end portions of the coils  61  and  62  from which the lead wires  611  and  621  are drawn out and the annular portions R 2  and R 3 . In this manner, the lead wire in a location where the lead wires  611  and  621  are drawn out from the coils  61  and  62  can be accommodated in the slits  111  and  112 . 
     At the time the stator S is manufactured, the coil  61  is first formed around the shaft  11 , and the lead wire  611  is accommodated in the slit  111 . After the above, a conductive wire is wound from the radially outside of the slit  111  to form the coil  62 . In this manner, as in the configuration illustrated in  FIG. 1 , one or more coils include the first coil  61  and the second coil  62  adjacent to each other in the axial direction, and the lead wire  611  of the first coil  61  is arranged radially inside the second coil  62 . In this manner, it is possible to suppress the lead wire  611  of the first coil  61  from jumping out radially outward from the slit  111 . 
     As illustrated in  FIG. 1 , an inner peripheral surface of the bearing  7 B is in contact with an outer peripheral surface of an end portion on the second side in the axial direction of the shaft  11 . The bearing  7 B connects the shaft  11  and the rotor  8 . The slits  111  and  112  have slit portions  111 B and  112 B extending over the entire axial area of the bearing  7 B. In this manner, the lead wires  611  and  621  can be drawn out to the outside through the slit portions  111 B and  112 B located radially inside the bearing  7 B. 
     In the above-described example embodiment, as illustrated in  FIG. 3 , the circumferential positions of the notch portions  121 B and  121 C coincide with each other. However, the circumferential positions do not need to coincide with each other as described below. 
       FIG. 6  is a perspective view of a partial configuration of the stator S according to a variation as viewed from the second side in the axial direction. As illustrated in  FIG. 6 , when viewed in the axial direction, the circumferential positions of the notch portions  121 B and  121 C are arranged between the pole teeth  42  and  52  adjacent to each other in the circumferential direction. In this manner, it is possible to suppress hinderance to a magnetic flux flowing through the pole teeth  42  and  52  via the shaft  11  and the annular portions R 2  and R 3  by the notch portions  121 B and  121 C. 
     Because of the circumferential positions of the notch portions  121 B and  121 C as described above, the circumferential positions of the notch portions  121 B and  121 C are different. Here, as illustrated in  FIG. 6 , the slit  111  has a slit portion  111 C extending in a direction having an axial component and a circumferential component between the notch portions  121 B and  121 C arranged in the axial direction. That is, the slit portion  111 C extends so as to approach more from the notch portion  121 B to  121 C in the circumferential direction toward the second side in the axial direction. In this manner, even if the circumferential positions of the notch portions  121 B and  121 C arranged in the axial direction are different, the lead wire  611  can be accommodated in the slit  111  from the radially inside of the notch portion  121 B to the radially inside of the other notch portion  121 C which are arranged in the axial direction. 
       FIG. 7  is a longitudinal cross-sectional view of a motor  101  having the stator S according to a variation. In the stator S according to the variation illustrated in  FIG. 7 , the disk portions  12 A,  12 B, and  12 C are separate from the shaft  11 . That is, the annular portions R 1 , R 2 , and R 3  are separate from the shaft  11 . 
     At the time the stator S is manufactured having such a configuration, the coil  61  is first formed around the shaft  11 , and the lead wire  611  drawn out from the coil  61  is accommodated in the slit  111 . After the above, the disk portion  12 B is fitted into the shaft  11  from the second side in the axial direction, and the disk portion  12 B is arranged at a predetermined position in the axial direction. After the above, the coil  62  is formed around the shaft  11 , and the lead wire  621  drawn out from the coil  62  is accommodated in the slit  112 . After the above, the disk portion  12 C is fitted into the shaft  11  from the second side in the axial direction, and the disk portion  12 C is arranged at a predetermined position in the axial direction. 
     In this manner, as illustrated in  FIG. 7 , a part of the lead wires  611  and  621  is arranged radially inside the disk portions  12 B and  12 C. That is, the lead wires  611  and  621  are arranged between a part of the slits  111  and  112  and radially inner ends of the annular portions R 2  and R 3 . In this manner, the annular portions R 2  and R 3  can suppress the lead wires  611  and  621  from jumping out of the slits  111  and  112  to the radially outward. 
     The disk portions  12 A,  12 B, and  12 C and the stator cores  2 ,  3 ,  4 , and  5  may be integrally formed to constitute one stator core. In this case, three stator cores to be constituted and the shaft  11  are separate from each other. 
     The present disclosure can be used for stepping motors used in various devices. 
     Features of the above-described example embodiments and the modifications thereof may be combined appropriately as long as no conflict arises. 
     While example embodiments of the present disclosure have been described above, it is to be understood that variations and modifications will be apparent to those skilled in the art without departing from the scope and spirit of the present disclosure. The scope of the present disclosure, therefore, is to be determined solely by the following claims.