JP2011172376A - Stator for brushless motor, brushless motor, and electric power steering apparatus, and method for manufacturing stator of brushless motor - Google Patents

Abstract

[PROBLEMS] To reduce the risk of a complicated configuration of a stator for a brushless motor.
A stator includes a stator core and an exciting coil provided on the stator core. The stator core includes a plurality of first core pieces 41 and one or more second core pieces 42. The first core piece 41 is laminated in the direction of the central axis Zr of the stator. The second core piece 42 is laminated together with the first core piece 41 in the central axis Zr direction. The second core piece 42 is in the direction of the central axis Zr in contact with the first core piece 41 and in the direction of the central axis Zr that is continuous with the base 43 and faces the side periphery of the plurality of stacked first core pieces 41. An extending portion 45 to be extended.
[Selection] Figure 7

Description

  The present invention relates to a stator structure of a brushless motor.

  In the brushless motor in which the brushless motor stator is disposed so as to cover the rotor, the brushless motor stator needs to be fixed to the housing. The stator for a brushless motor is fixed to the housing by press fitting, shrink fitting, adhesion, or welding, for example. At this time, the stator for the brushless motor may be distorted by receiving a force from the housing. Thereby, a brushless motor provided with such a stator for brushless motors may increase iron loss.

  As a technique capable of reducing this iron loss, for example, Patent Document 1 discloses an inner rotor type brushless motor in which an elastic member having elasticity or viscoelasticity is fitted in an annular groove formed on the outer periphery of a brushless motor stator core. Has been. Patent Document 2 discloses a technique for reducing the area of contact between the housing and the stator core by providing a recess in the back yoke of the stator core in order to reduce iron loss due to compressive stress.

JP 2007-189812 A JP 2007-104830 A

  The technique disclosed in Patent Document 1 realizes a floating structure by supporting a stator core on a housing with an elastic member. For this reason, the technique disclosed in Patent Document 1 is insufficiently fixed in the axial direction and the rotational direction of the stator, and the reliability is lowered. In addition, there is a concern that the balance between the stator and the air gap is lost, and vibration noise increases.

  In the technique disclosed in Patent Document 2, it is necessary to secure a contact area between the stator core and the housing so that the stator core and the housing are sufficiently fixed. As a result, the technique disclosed in Patent Document 2 partially increases the thickness of the back yoke of the stator core or decreases the back yoke of the portion where the recess is formed, while the range in which the compressive stress acts is expanded. It is necessary to let Therefore, in the technique disclosed in Patent Document 2, the diameter of the stator core is increased, and as a result, the mass of the stator core is increased. Further, when the thickness of the back yoke in the portion where the concave portion is formed is reduced, the technique disclosed in Patent Document 2 is concerned about an increase in loss torque.

  The technique disclosed in Patent Document 1 requires an elastic member as an additional member. Moreover, the technique currently disclosed by patent document 1 may require the groove | channel for inserting an additional member. Thereby, the technique disclosed in Patent Document 1 may be complicated in the configuration of the brushless motor stator.

  The present invention has been made in view of the above, and an object of the present invention is to reduce the risk of the configuration of the brushless motor stator becoming complicated.

  In order to solve the above-described problems and achieve the object, a brushless motor stator according to the present invention includes a plurality of first core pieces stacked in the central axis direction of the stator core, and the first core in the central axis direction. One or more second core pieces stacked together with the pieces, and an exciting coil provided on the stator core, the second core piece being continuous with the base portion and the base portion in contact with the first core pieces. And extending portions extending in the direction of the central axis so as to face the side peripheral portions of the stacked first core pieces.

  With the above configuration, the brushless motor stator according to the present invention does not require an additional member such as an O-ring, an elastic member, or a resin member. In addition, the brushless motor stator according to the present invention does not require the formation of a groove into which the additional member is fitted. Therefore, the brushless motor stator according to the present invention can reduce the risk of the configuration of itself (brushless motor stator) becoming complicated.

  The stator core is formed by laminating a plurality of thin plate-like core pieces (magnetic steel plates). If the thickness of the plurality of second core pieces is configured to be uniform, the brushless motor stator according to the present invention can make the gap between the housing and the stator core uniform. In addition, by reducing the thickness of the second core piece, the brushless motor stator according to the present invention can reduce the gap between the stator core and the stator core. Thereby, the stator for brushless motors according to the present invention can reduce the increase in the stator core.

  In addition, when the stator core is press-fitted, the stator core is provided with a shim allowance. The stator for a brushless motor according to the present invention can easily change the squeeze cost by changing the thickness of the extending portion of the second core piece. For example, the extending portion is formed thinner or thicker by changing the number of times of pressing.

  Further, the central portion in the circumferential direction of the back yoke of the stator core is a portion having a low magnetic flux density. Therefore, the brushless motor stator according to the present invention is the case where the root portion of the extension portion and the base portion is temporarily distorted by compressive stress by providing the extension portion at the center portion in the circumferential direction of the back yoke of the stator core. In addition, the distorted portion can be reduced as compared with the case where the side peripheral portion of the stator core is pressed into contact with the housing. Therefore, the brushless motor stator according to the present invention can reduce the increase in iron loss by reducing the distortion of the stator core.

  As a preferred aspect of the present invention, it is desirable that a plurality of the second core pieces are arranged in the central axis direction.

  With the above configuration, the number of extending portions of the brushless motor stator according to the present invention is increased. The extending portion is a portion for fixing the brushless motor stator to the cylindrical housing. Since the total area of the extending portion increases, the brushless motor stator according to the present invention can reduce the risk of insufficient fixation between itself (the brushless motor stator) and the cylindrical housing. If the area of the side peripheral portion of the brushless motor stator that contacts the inner peripheral surface of the cylindrical housing is insufficient, the brushless motor stator according to the present invention has a larger area of the extending portion. Just do it. Specifically, in the brushless motor stator according to the present invention, the size of the extending portion in the central axis direction of the brushless motor stator is enlarged, or the size of the extending portion in the circumferential direction around the central axis is increased. It may be enlarged. Thereby, the stator for brushless motors according to the present invention can more suitably reduce the risk of insufficient fixation between itself (brushless motor stator) and the housing.

  As a preferred aspect of the present invention, it is desirable that the extending portion protrudes from the side peripheral portion in a direction orthogonal to the central axis direction.

  With the above configuration, the brushless motor stator according to the present invention has an extending portion interposed between the side peripheral portion of itself (brushless motor stator) and the inner peripheral surface of the cylindrical housing. A gap can be secured between the inner peripheral surface of the cylindrical housing. In other words, the brushless motor stator according to the present invention can realize a so-called floating structure. Therefore, the brushless motor stator according to the present invention can reduce the area of the side peripheral portion that contacts the inner peripheral surface of the cylindrical housing. As a result, the brushless motor stator according to the present invention can reduce distortion (deformation) caused by an external force received from the cylindrical housing. The external force is a force received when the tube is press-fitted or shrink-fitted into the cylindrical housing. Thereby, the stator for brushless motors can reduce the deterioration of the magnetic characteristics resulting from the distortion, specifically the iron loss of itself (brushless motor stator).

  The stator for a brushless motor according to the present invention can realize a so-called floating structure without requiring an additional member such as an O-ring, an elastic member, or a resin member. Further, the brushless motor stator according to the present invention can realize a so-called floating structure without requiring the formation of a groove into which the additional member is fitted. Therefore, the brushless motor stator according to the present invention can realize a so-called floating structure with an easier configuration, and can suppress the manufacturing cost of itself (brushless motor stator).

  As a preferred aspect of the present invention, the stator core includes a plurality of divided cores arranged in a circumferential direction around the central axis and combined with each other, and the second core pieces are adjacent to each other in the circumferential direction. It is desirable that the two extending portions respectively provided in the core and adjacent in the circumferential direction are coupled to each other.

  By the said structure, the stator for brushless motors which concerns on this invention can integrate a some division | segmentation core by the adjacent extending | stretching parts being couple | bonded. Here, when integrating a plurality of split cores, for example, there is a method of welding side peripheral portions of adjacent split cores in the circumferential direction. However, in this method, the iron loss of the brushless motor stator may increase depending on the strength of the welded portion, the position where the welding is performed, and the shape of the electrode used when performing the welding. However, the extension part which adjoins the stator for brushless motors which concerns on this invention is couple | bonded. The extending portion is a portion that hardly affects the iron loss of the brushless motor stator. Therefore, the brushless motor stator according to the present invention can reduce iron loss. As a result, the brushless motor stator according to the present invention can reduce the loss torque of the brushless motor.

  As a preferred aspect of the present invention, it is desirable that the second core piece has extending portions at both ends in the circumferential direction.

  By the said structure, the distance of the extending parts adjacent in the circumferential direction becomes short. Therefore, in the brushless motor stator according to the present invention, the extending portions adjacent to each other in the circumferential direction are easily coupled.

  In order to solve the above-described problems and achieve the object, a brushless motor according to the present invention includes a cylindrical housing, the brushless motor stator provided in the cylindrical housing, and the brushless motor stator. And a rotor provided to be surrounded.

  With the above configuration, the brushless motor according to the present invention does not require an additional member such as an O-ring, an elastic member, or a resin member. Further, the brushless motor according to the present invention does not require the formation of a groove into which the additional member is fitted. Therefore, the brushless motor according to the present invention can reduce the risk of the configuration of the brushless motor stator becoming complicated.

  Further, the brushless motor according to the present invention has an extending portion interposed between the side peripheral portion of the brushless motor stator and the inner peripheral surface of the cylindrical housing, so that the side peripheral portion of the brushless motor stator and the cylindrical housing When a gap is generated between the inner peripheral surface and the inner peripheral surface, the following effects are obtained. The brushless motor according to the present invention can realize a so-called floating structure. Therefore, the brushless motor which concerns on this invention can reduce the area which contacts the internal peripheral surface of a cylindrical housing among the side peripheral parts of the stator for brushless motors. As a result, the brushless motor according to the present invention can reduce the distortion (deformation) of the brushless motor stator caused by the external force received from the cylindrical housing. Thereby, the brushless motor can reduce the deterioration of the magnetic characteristics of the brushless motor stator caused by the distortion, specifically the iron loss of the brushless motor stator.

  Further, in the brushless motor according to the present invention, the extending portion is in contact with both the side peripheral portion of the brushless motor stator and the inner peripheral surface of the cylindrical housing, and supports the brushless motor stator in the cylindrical housing. The following effects are obtained. The brushless motor according to the present invention can reduce the risk of insufficient fixing between the brushless motor stator and the cylindrical housing. If the area of the side peripheral portion of the brushless motor stator that contacts the inner peripheral surface of the cylindrical housing is insufficient, the brushless motor according to the present invention has a larger extension area. Good. Specifically, in the brushless motor according to the present invention, the dimension of the extending part in the central axis direction of the stator for the brushless motor is enlarged, or the dimension of the extending part in the circumferential direction around the central axis is enlarged. Just do it. Thereby, the brushless motor which concerns on this invention can reduce more suitably the possibility that fixation with the stator for brushless motors and a cylindrical housing may become inadequate.

  In order to solve the above-described problems and achieve the object, an electric power steering apparatus according to the present invention is characterized in that an auxiliary steering torque is obtained by the above-described brushless motor.

  With the above configuration, the electric power steering apparatus according to the present invention does not require an additional member such as an O-ring, an elastic member, or a resin member. Moreover, the electric power steering apparatus according to the present invention does not require the formation of a groove into which the additional member is fitted. Therefore, the electric power steering apparatus according to the present invention can reduce the risk of the configuration of the brushless motor stator becoming complicated.

  The electric power steering apparatus according to the present invention includes an extension portion interposed between a side peripheral portion of the brushless motor stator and an inner peripheral surface of the cylindrical housing, and the side peripheral portion of the brushless motor stator and the cylindrical shape. When a gap is formed between the inner peripheral surface of the housing, the following effects are obtained. The electric power steering apparatus according to the present invention can realize a so-called floating structure. Therefore, the electric power steering device according to the present invention can reduce the area of the side peripheral portion of the brushless motor stator that contacts the inner peripheral surface of the cylindrical housing. As a result, the electric power steering apparatus according to the present invention can reduce the distortion (deformation) of the brushless motor stator caused by the external force received from the cylindrical housing. As a result, the electric power steering apparatus according to the present invention can reduce the deterioration of the magnetic characteristics of the brushless motor stator due to the distortion, specifically the iron loss of the brushless motor stator.

  In the electric power steering apparatus according to the present invention, the extending portion is in contact with both the side peripheral portion of the brushless motor stator and the inner peripheral surface of the cylindrical housing, and the brushless motor stator is supported in the cylindrical housing. When it does, the following effects are produced. The electric power steering apparatus according to the present invention can reduce the possibility that the stator for the brushless motor and the cylindrical housing are insufficiently fixed. If the area of the side peripheral portion of the brushless motor stator that contacts the inner peripheral surface of the cylindrical housing is insufficient, the electric power steering device according to the present invention has a larger area of the extending portion. Just do it. Specifically, in the electric power steering device according to the present invention, the dimension of the extending part in the central axis direction of the stator for the brushless motor is enlarged, or the dimension of the extending part in the circumferential direction around the central axis is increased. It may be enlarged. Thereby, the electric power steering device according to the present invention can more suitably reduce the possibility that the fixing between the brushless motor stator and the cylindrical housing becomes insufficient.

  In order to solve the above-described problems and achieve the object, a method for manufacturing a stator for a brushless motor according to the present invention includes laminating a plurality of first core pieces and one or more second core pieces in the central axis direction of the stator core. And a step of bending the second core piece so that extending portions protruding from the plurality of first core pieces in the second core piece approach the central axis direction.

  With the above configuration, if the stator manufacturing method for a brushless motor according to the present invention is used, an additional member such as an O-ring, an elastic member, or a resin member is not required. Moreover, if the brushless motor stator manufacturing method according to the present invention is used, it is not necessary to form a groove into which the additional member is fitted. Therefore, if the method for manufacturing a brushless motor stator according to the present invention is used, the risk of the configuration of the brushless motor stator being complicated can be reduced.

  Further, the brushless motor stator manufacturing method according to the present invention includes an extending portion interposed between a side peripheral portion of the brushless motor stator and an inner peripheral surface of the cylindrical housing, and a side peripheral portion of the brushless motor stator. When a gap is generated between the inner surface of the cylindrical housing, the following effects are obtained. If the brushless motor stator manufacturing method according to the present invention is used, a so-called floating structure can be realized. Therefore, if the stator manufacturing method for brushless motors concerning this invention is used, the area which contacts the internal peripheral surface of a cylindrical housing among the side peripheral parts of the stator for brushless motors can be reduced. As a result, if the method for manufacturing a brushless motor stator according to the present invention is used, distortion (deformation) of the brushless motor stator caused by an external force received from the cylindrical housing can be reduced. Thereby, if the stator manufacturing method for brushless motors concerning this invention is used, the deterioration of the magnetic characteristic of the stator for brushless motors resulting from the said distortion, specifically, the iron loss of the stator for brushless motors can be reduced.

  In the brushless motor stator manufacturing method according to the present invention, the extending portion is in contact with both the side peripheral portion of the brushless motor stator and the inner peripheral surface of the cylindrical housing, so that the brushless motor stator is placed in the cylindrical housing. The following effects are exhibited when supporting the above. If the method for manufacturing a brushless motor stator according to the present invention is used, it is possible to reduce the risk of insufficient fixing between the brushless motor stator and the cylindrical housing. In addition, if the area which contacts the internal peripheral surface of a cylindrical housing is insufficient among the side peripheral parts of the stator for brushless motors, the area of an extending part should just be formed larger. Specifically, the dimension of the extending part in the central axis direction of the stator for the brushless motor may be enlarged, or the dimension of the extending part in the circumferential direction around the central axis may be enlarged. Thereby, if the stator manufacturing method for brushless motors concerning this invention is used, a possibility that fixation with the stator for brushless motors and a cylindrical housing may become inadequate can be reduced more suitably.

  The present invention can reduce the risk of the configuration of the brushless motor stator becoming complicated.

FIG. 1 is a configuration diagram of an electric power steering apparatus including a brushless motor according to the first embodiment. FIG. 2 is a front view for explaining an example of a speed reducer included in the electric power steering apparatus according to the first embodiment. FIG. 3 is a cross-sectional view schematically showing the configuration of the motor of the first embodiment on a virtual plane including the central axis. FIG. 4 is a cross-sectional view schematically showing the configuration of the motor according to the first embodiment, taken along a virtual plane orthogonal to the central axis. FIG. 5 is a perspective view schematically showing the split core according to the first embodiment. FIG. 6 is a perspective view schematically showing the split core before the extending portion of Embodiment 1 is bent. FIG. 7 is a perspective view schematically showing the split core according to the first embodiment after the bent portion is bent. FIG. 8 is a perspective view schematically showing a state where the split cores of Embodiment 1 after the bent portion is bent are combined. FIG. 9 is an explanatory diagram schematically illustrating a side peripheral portion of the stator core according to the first embodiment. FIG. 10 is an explanatory view schematically showing the stator core of Embodiment 1 before the bent portion is bent. FIG. 11 is an explanatory view schematically showing the stator core of the first embodiment after the bent portion is bent. FIG. 12 is an explanatory view schematically showing a state in which the stator core of Embodiment 1 is fitted in the cylindrical housing as seen in the central axis direction. FIG. 13 is a cross-sectional view schematically showing a state in which the stator core of Embodiment 1 is fitted into the cylindrical housing, cut along a virtual plane including the central axis. FIG. 14 is a cross-sectional view showing the extension portion of Modification 1 cut along a virtual plane including the central axis. FIG. 15 is a cross-sectional view showing the extension part of Modification 2 cut along a virtual plane including the central axis. FIG. 16 is a perspective view schematically showing an extending portion of Modification 3. FIG. 17 is a perspective view schematically showing the split core according to the second embodiment before the bent portion is bent. FIG. 18 is a perspective view schematically showing the split core according to the second embodiment after the bent portion is bent. FIG. 19 is an explanatory diagram schematically illustrating a side peripheral portion of the stator core according to the third embodiment.

  Hereinafter, the present invention will be described in detail with reference to the drawings. It should be noted that the present invention is not limited by the modes for carrying out the invention (hereinafter referred to as embodiments). In addition, constituent elements in the following embodiments include those that can be easily assumed by those skilled in the art and those that are substantially the same. In the present embodiment, an example in which the brushless motor according to the present invention is applied to an electric power steering device (EPS) will be described, but the application target of the present invention is not limited to the electric power steering device. Even when the present invention is applied to an electric power steering apparatus, the method is not limited.

(Embodiment 1)
FIG. 1 is a configuration diagram of an electric power steering apparatus including a brushless motor according to the first embodiment. First, an outline of an electric power steering apparatus including the brushless motor according to the present embodiment will be described with reference to FIG. The electric power steering device 80 includes a steering wheel 81, a steering shaft 82, a steering force assist mechanism 83, a universal joint 84, a lower shaft 85, a universal joint 86, in the order in which the force applied from the steering wheel is transmitted. A pinion shaft 87, a steering gear 88, and a tie rod 89 are provided. The electric power steering device 80 includes an ECU (Electronic Control Unit) 90, a torque sensor 91a, and a vehicle speed sensor 91b.

  The steering shaft 82 includes an input shaft 82a and an output shaft 82b. The input shaft 82a has one end connected to the steering wheel 81 and the other end connected to the steering force assist mechanism 83 via the torque sensor 91a. The output shaft 82 b has one end connected to the steering force assist mechanism 83 and the other end connected to the universal joint 84. In the present embodiment, the input shaft 82a and the output shaft 82b are made of a magnetic material such as iron.

  The lower shaft 85 has one end connected to the universal joint 84 and the other end connected to the universal joint 86. The pinion shaft 87 has one end connected to the universal joint 86 and the other end connected to the steering gear 88. Steering gear 88 includes a pinion 88a and a rack 88b. The pinion 88a is connected to the pinion shaft 87. The rack 88b meshes with the pinion 88a. The steering gear 88 is configured as a rack and pinion type. The steering gear 88 converts the rotational motion transmitted to the pinion 88a into a linear motion by the rack 88b. The tie rod 89 is connected to the rack 88b.

  The steering force assist mechanism 83 includes a speed reducer 92 and the brushless motor 10. The reduction gear 92 is connected to the output shaft 82b. The brushless motor 10 is connected to the speed reducer 92 and generates auxiliary steering torque. In the electric power steering device 80, a steering column is constituted by the steering shaft 82, the torque sensor 91a, and the speed reducer 92. The brushless motor 10 gives auxiliary steering torque to the output shaft 82b of the steering column. That is, the electric power steering apparatus 80 of this embodiment is a column assist system.

  FIG. 2 is a front view for explaining an example of a speed reducer included in the electric power steering apparatus according to the first embodiment. FIG. 2 shows a part in cross section. The speed reducer 92 is a worm speed reducer. The reduction gear 92 includes a reduction gear housing 93, a worm 94, a ball bearing 95 a, a ball bearing 95 b, a worm wheel 96, and a holder 97. The worm 94 is coupled to the shaft 21 of the brushless motor 10 by a spline or an elastic coupling. The worm 94 is held in the speed reducer housing 93 so as to be rotatable by a ball bearing 95 a and a ball bearing 95 b held by the holder 97. The worm wheel 96 is rotatably held by the speed reducer housing 93. The worm teeth 94 a formed on a part of the worm 94 mesh with the worm wheel teeth 96 a formed on the worm wheel 96. The rotational force of the brushless motor 10 is transmitted to the worm wheel 96 through the worm 94 to rotate the worm wheel 96. The reduction gear 92 increases the torque of the brushless motor 10 by the worm 94 and the worm wheel 96. Then, the reduction gear 92 gives an auxiliary steering torque to the output shaft 82b of the steering column shown in FIG.

  The torque sensor 91a shown in FIG. 1 detects the driver's steering force transmitted to the input shaft 82a via the steering wheel 81 as a steering torque. The vehicle speed sensor 91b detects the traveling speed of the vehicle on which the electric power steering device 80 is mounted. The ECU 90 is electrically connected to the brushless motor 10, the torque sensor 91a, and the vehicle speed sensor 91b. The ECU 90 controls the operation of the brushless motor 10. Moreover, ECU90 acquires a signal from each of the torque sensor 91a and the vehicle speed sensor 91b. That is, the ECU 90 acquires the steering torque T from the torque sensor 91a, and acquires the traveling speed V of the vehicle from the vehicle speed sensor 91b. The ECU 90 is supplied with electric power from a power supply device (for example, a vehicle-mounted battery) 99 with the ignition switch 98 turned on. The ECU 90 calculates an assist steering command value of the assist command based on the steering torque T and the traveling speed V. Then, the ECU 90 adjusts the current value supplied to the brushless motor 10 based on the calculated auxiliary steering command value.

  The steering force of the driver (driver) input to the steering wheel 81 is transmitted to the speed reduction device 92 of the steering force assist mechanism 83 via the input shaft 82a. At this time, the ECU 90 acquires the steering torque T input to the input shaft 82a from the torque sensor 91a, and acquires the traveling speed V from the vehicle speed sensor 91b. The ECU 90 controls the operation of the brushless motor 10. The auxiliary steering torque created by the brushless motor 10 is transmitted to the speed reducer 92. The steering torque (including auxiliary steering torque) output via the output shaft 82 b is transmitted to the lower shaft 85 via the universal joint 84 and further transmitted to the pinion shaft 87 via the universal joint 86. The steering force transmitted to the pinion shaft 87 is transmitted to the tie rod 89 via the steering gear 88 to steer the steered wheels. Next, the brushless motor 10 will be described.

  FIG. 3 is a cross-sectional view schematically showing the configuration of the motor of the first embodiment on a virtual plane including the central axis. FIG. 4 is a cross-sectional view schematically showing the configuration of the motor according to the first embodiment, taken along a virtual plane orthogonal to the central axis. As shown in FIG. 3, the brushless motor 10 includes a housing 11, a bearing 12, a bearing 13, a resolver 14, a rotor 20, and a stator 30 as a brushless motor stator. The housing 11 includes a cylindrical housing 11a and a front bracket 11b. The front bracket 11b is formed in a substantially disc shape and is attached to the cylindrical housing 11a so as to close one open end of the cylindrical housing 11a. The cylindrical housing 11a is formed with a bottom 11c at the end opposite to the front bracket 11b so as to close the end. The bottom part 11c is formed integrally with the cylindrical housing 11a, for example. As a magnetic material forming the cylindrical housing 11a, for example, a general steel material such as SPCC (Steel Plate Cold Commercial), electromagnetic soft iron, or the like can be applied. The front bracket 11b serves as a flange when the brushless motor 10 is attached to a desired device.

  The bearing 12 is provided inside the cylindrical housing 11a and at a substantially central portion of the front bracket 11b. The bearing 13 is provided inside the cylindrical housing 11a and at a substantially central portion of the bottom portion 11c. The bearing 12 rotatably supports one end of a shaft 21 that is a part of the rotor 20 disposed inside the cylindrical housing 11a. The bearing 13 rotatably supports the other end of the shaft 21. Thereby, the shaft 21 rotates around the central axis Zr. The resolver 14 is supported by a terminal block 15 provided on the front bracket 11b side of the shaft 21. The resolver 14 detects the rotational position of the rotor 20 (shaft 21). The resolver 14 includes a resolver rotor 14a and a resolver stator 14b. The resolver rotor 14a is attached to the circumferential surface of the shaft 21 by press fitting or the like. The resolver stator 14b is disposed to face the resolver rotor 14a with a predetermined gap.

  The rotor 20 is provided inside the cylindrical housing 11a so as to be rotatable about the central axis Zr with respect to the cylindrical housing 11a. The rotor 20 includes a shaft 21, a rotor core 22, and a magnet 23. The shaft 21 is formed in a cylindrical shape. The rotor core 22 is formed in a cylindrical shape. The rotor core 22 is not limited to a perfect cylinder, and may have a groove for arranging the magnet 23. In addition, the rotor core 22 may have a polygonal bottom surface by forming a surface along the side periphery for the side periphery of the magnet 23. The rotor core 22 is manufactured by laminating thin plates such as electromagnetic steel plates and cold rolled steel plates by means of adhesion, boss, caulking or the like. The rotor core 22 is stacked in a progressive mold and discharged from the mold. The rotor core 22 is fixed to the shaft 21 by press-fitting the shaft 21 into, for example, a hollow portion thereof. The shaft 21 and the rotor core 22 may be integrally molded.

  A plurality of magnets 23 (2 × n, n is an integer) are provided on the outer periphery of the rotor core 22. The magnet 23 is a permanent magnet, and the S pole and the N pole are alternately arranged at equal intervals in the circumferential direction of the rotor core 22. For example, the magnet 23 is attached to the rotor core 22 by magnetic force. The magnet 23 may be embedded in the rotor core 22. The magnet 23 is covered with a non-magnetic cover (for example, a heat-shrinkable tube) for reducing the risk of scattering due to centrifugal force. In the present embodiment, the magnet 23 has a divided shape (segment structure).

  The stator 30 is provided in a cylindrical shape so as to surround the magnet 23 of the rotor 20 inside the cylindrical housing 11a. The stator 30 is attached, for example, by being fitted to the inner peripheral surface 11d of the cylindrical housing 11a. The central axis of the stator 30 coincides with the central axis Zr of the rotor 20. The stator 30 includes a cylindrical stator core 31 and an excitation coil 37. In the stator 30, an exciting coil 37 is wound around the stator core 31. As shown in FIG. 4, the stator core 31 includes a plurality of divided cores 32. The plurality of split cores 32 are arranged at equal intervals in the circumferential direction (the direction along the inner peripheral surface 11d of the cylindrical housing 11a) centered on the central axis Zr. Hereinafter, the circumferential direction around the central axis Zr is referred to as the circumferential direction. The stator core 31 is configured by combining a plurality of divided cores 32. The stator core 31 is press-fitted into the cylindrical housing 11a, so that the stator 30 is provided in the cylindrical housing 11a in an annular state. The stator core 31 and the cylindrical housing 11a may be fixed by adhesion, shrink fitting, or the like in addition to press-fitting.

  FIG. 5 is a perspective view schematically showing the split core according to the first embodiment. The split core 32 shown in FIG. 5 is formed by stacking and bundling a plurality of core pieces formed in substantially the same shape in the direction of the central axis Zr. The split core 32 is formed of a magnetic material. The split core 32 has a back yoke 33 and teeth 34. The back yoke 33 includes an arc-shaped portion. The back yoke 33 forms an annular shape when the plurality of divided cores 32 are combined. The teeth 34 are portions extending from the inner peripheral surface of the back yoke 33 toward the rotor 20.

  The exciting coil 37 shown in FIG. 4 is a linear electric wire. The exciting coil 37 is concentratedly wound around the outer periphery of the tooth 34 of the split core 32 shown in FIG. 5 via an insulator 37a. The insulator 37a is a member for insulating the exciting coil 37 and the split core 32, and is formed of a heat resistant member. By combining a plurality of stator cores 31 thus configured as shown in FIG. 4, the stator 30 has a shape that can surround the rotor 20. Here, the brushless motor 10 of the present embodiment is characterized by the configuration of the stator 30, particularly the configuration of the split core 32. Hereinafter, a more detailed configuration of the split core 32 and a method for manufacturing the stator 30 will be described.

  FIG. 6 is a perspective view schematically showing the split core before the extending portion of Embodiment 1 is bent. The split core 32 includes a plurality of first core pieces 41 and one or more second core pieces 42. The first core piece 41 and the second core piece 42 are plate-like members. The plurality of first core pieces 41 are formed in substantially the same shape. The second core piece 42 is formed in a shape different from that of the first core piece 41. The second core piece 42 includes a base portion 43, a bent portion 44, and an extending portion 45. The base 43 is a part that contacts the first core piece 41. The base 43 has substantially the same shape as the first core piece 41 and includes a back yoke 43a and teeth 43b. The bent portion 44 is provided on the back yoke 43a. The bent portion 44 is the most radially outer portion (a portion away from the central axis Zr) of the back yoke 43a. That is, the bent portion 44 is provided in a portion of the back yoke 43a that faces the inner peripheral surface 11d when the stator 30 is fitted into the cylindrical housing 11a as shown in FIG.

  In the present embodiment, one bent portion 44 is provided at the center in the circumferential direction of the back yoke 43a. The extending portion 45 is formed continuously with the bent portion 44. The extending portion 45 is formed so as to extend from the base portion 43 in a direction (radial direction) orthogonal to the central axis Zr. The shape of the extending portion 45 is, for example, a rectangle. However, the shape of the extending portion 45 is not limited to a rectangle. By being configured in this way, the second core piece 42 is formed in a substantially cross shape.

  Here, although mentioned later for details, the 2nd core piece 42 is bent so that the extending | stretching part 45 may approach the central axis Zr. The first core piece 41 has a guide groove 41a into which a part of the bent extended portion 45 is inserted. The guide groove 41a is formed on the radially outer side of the first core piece 41 (the portion that forms the side peripheral portion 30a of the stator 30 when the first core piece 41 is laminated). The guide groove 41a is a groove that is recessed in a direction approaching the central axis Zr. The guide groove 41a is formed such that the depth (the dimension in the direction orthogonal to the central axis Zr) of itself (the guide groove 41a) is smaller than the thickness of the extending portion 45. Thereby, the extending | stretching part 45 protrudes from the guide groove 41a in the direction orthogonal to the central axis Zr. The guide groove 41a may not be formed. However, the stator 30 having the guide groove 41a improves the possibility that the second core piece 42 is bent more accurately. Further, in the stator 30, the extending portion 45 partially inserted into the guide groove 41 a can reduce the circumferential displacement of each first core piece 41. Next, a method for manufacturing the stator 30 will be described.

  FIG. 7 is a perspective view schematically showing the split core according to the first embodiment after the bent portion is bent. FIG. 8 is a perspective view schematically showing a state where the split cores of Embodiment 1 after the bent portion is bent are combined. FIG. 9 is an explanatory diagram schematically illustrating a side peripheral portion of the stator core according to the first embodiment. First, the split core 32 is assembled to the stator 30. As shown in FIG. 6, the split core 32 includes a plurality of first core pieces 41 and a second core piece 42 stacked in the central axis Zr direction. In the present embodiment, one second core piece 42 is provided at each end of the plurality of first core pieces 41 in the direction of the central axis Zr (two in total). In addition, the position where the 2nd core piece 42 is arrange | positioned is not limited to the both ends in the center axis Zr direction of the 1st core piece 41 arrange | positioned in multiple numbers.

  Next, as shown in FIG. 7, the bent portion 44 of the second core piece 42 is bent in the stator 30. The bent portion 44 of the second core piece 42 is bent so that the extending portion 45 extends along the central axis Zr (so that the extending portion 45 approaches the central axis Zr). The bent portion 44 is bent toward the central portion of the split core 32 in the central axis Zr direction. Next, the stator 30 is configured by combining the plurality of divided cores 32 thus configured, as shown in FIGS. 8 and 9. Although not shown in FIGS. 8 and 9, in the stator 30, an exciting coil 37 is wound around each divided core 32 via an insulator 37 a shown in FIG. 9.

  FIG. 10 is an explanatory view schematically showing the stator core of Embodiment 1 before the bent portion is bent. FIG. 11 is an explanatory view schematically showing the stator core of the first embodiment after the bent portion is bent. Here, the timing at which the bent portion 44 is bent is not limited before the plurality of split cores 32 are combined. In this case, as shown in FIG. 10, the stator 30 has a plurality of split cores 32 combined before the bent portion 44 is bent. Then, as shown in FIG. 11, after the plurality of divided cores 32 are combined, the bent portion 44 is bent in the direction of the central axis Zr. Thereby, the stator 30 is comprised.

  FIG. 12 is an explanatory view schematically showing a state in which the stator core of Embodiment 1 is fitted in the cylindrical housing as seen in the central axis direction. FIG. 13 is a cross-sectional view schematically showing a state in which the stator core of Embodiment 1 is fitted into the cylindrical housing, cut along a virtual plane including the central axis. Next, as shown in FIGS. 12 and 13, the stator 30 is fitted into the cylindrical housing 11 a by, for example, press fitting or shrink fitting. At this time, the extending portion 45 is interposed between the side peripheral portion 30a of the stator 30 and the inner peripheral surface 11d of the cylindrical housing 11a as shown in FIG. The side peripheral portion 30a of the stator 30 is a portion formed by a radially outer portion of the plurality of first core pieces 41, and is a portion facing the inner peripheral surface 11d of the cylindrical housing 11a. Since the extending portion 45 is interposed between the side peripheral portion 30a and the inner peripheral surface 11d, the stator 30 has a gap between the side peripheral portion 30a of the stator 30 and the inner peripheral surface 11d of the cylindrical housing 11a. H is generated. In this way, the stator 30 is attached to the housing 11.

  With the above configuration, the stator 30 can ensure a gap H between the side peripheral portion 30a and the inner peripheral surface 11d of the cylindrical housing 11a. Therefore, the stator 30 can reduce the area which contacts the inner peripheral surface 11d of the cylindrical housing 11a in the side peripheral portion 30a. As a result, the stator 30 can reduce distortion (deformation) caused by an external force received from the cylindrical housing 11a. The external force is a force received when the tube housing 11a is press-fitted or shrink-fitted. Thereby, the stator 30 can reduce the deterioration of the magnetic characteristics resulting from the distortion, specifically the iron loss of itself (the stator 30).

  The extending portion 45 contacts both the side peripheral portion 30a and the inner peripheral surface 11d of the cylindrical housing 11a to support the stator 30 in the cylindrical housing 11a. Temporarily, when the area which contacts the internal peripheral surface 11d of the cylindrical housing 11a is insufficient among the side peripheral parts 30a, the stator 30 should just be formed so that the area of the extending | stretching part 45 may be larger. Specifically, in the stator 30, the dimension in the central axis Zr direction of the extending part 45 shown in FIG. 8 may be increased, or the dimension in the circumferential direction of the extending part 45 may be increased. Thereby, the stator 30 can reduce a possibility that fixation with self (stator 30) and the cylindrical housing 11a may become inadequate.

  In addition, the stator 30 of the present embodiment can ensure the gap H (realize a so-called floating structure) without requiring an additional member such as an O-ring, an elastic member, or a resin member. Further, the stator 30 can secure the gap H (realize a so-called floating structure) without requiring the formation of a groove into which the additional member is fitted. Therefore, the stator 30 can secure the gap H (so-called floating structure) by an easier manufacturing method, and can suppress the manufacturing cost of itself (the stator 30).

(Modification 1)
FIG. 14 is a cross-sectional view showing the extension portion of Modification 1 cut along a virtual plane including the central axis. The stator 30A of the first modification shown in FIG. 14 has a configuration in which the extending portion 45A is different from the extending portion 45 described above (for example, shown in FIG. 7). The extending portion 45A is an elastic member. The extending portion 45A is, for example, a leaf spring. The extending portion 45A is provided so as to float on the radially outer side (the direction away from the central axis Zr) from the side peripheral portion 30a of the stator 30. That is, the bent portion 44 is bent so that the narrow angle formed by the extending portion 45A and the base portion 43 is larger than 90 °. Thus, in the stator 30A, a gap H1 is generated between the extending portion 45A and the side peripheral portion 30a. When the stator 30A is fitted into the inner peripheral surface 11d, the bent portion 44 is elastically deformed, and the extending portion 45A approaches the side peripheral portion 30a.

  With the above configuration, when the stator 30A is fitted into the inner peripheral surface 11d, the bent portion 44 is elastically deformed, and the extending portion 45A approaches the inner peripheral surface 11d of the cylindrical housing 11a. Thereby, for example, even if the gap H between the side peripheral portion 30a and the inner peripheral surface 11d of the cylindrical housing 11a is larger than the plate thickness of the extending portion 45A due to insufficient processing accuracy. The extending portion 45A is in contact with the inner peripheral surface 11d. The extending portion 45A applies a force radially outward (in a direction away from the central axis Zr) to the cylindrical housing 11a. Thereby, even if the gap H between the side peripheral part 30a and the inner peripheral surface 11d of the cylindrical housing 11a is larger than the plate thickness of the extending part 45A, the stator 30A and itself (stator 30A) The possibility that the fixing with the cylindrical housing 11a becomes insufficient can be reduced.

  Further, with the above configuration, the stator 30A can secure a gap H between the side peripheral portion 30a and the inner peripheral surface 11d of the cylindrical housing 11a. Therefore, the stator 30A can reduce the area which contacts the inner peripheral surface 11d of the cylindrical housing 11a in the side peripheral portion 30a. As a result, the stator 30A can reduce distortion (deformation) caused by an external force received from the cylindrical housing 11a. The external force is a force received when the tube housing 11a is press-fitted or shrink-fitted. Thereby, the stator 30A can reduce the deterioration of the magnetic characteristics due to the strain, specifically the iron loss of itself (the stator 30A).

  Further, the stator 30A can secure the gap H (realize a so-called floating structure) without requiring an additional member such as an O-ring, an elastic member, or a resin member. Further, the stator 30A can secure the gap H (realize a so-called floating structure) without requiring the formation of a groove into which the additional member is fitted. Therefore, the stator 30A can secure the gap H (so-called floating structure) by an easier manufacturing method, and can suppress the manufacturing cost of itself (the stator 30A).

(Modification 2)
FIG. 15 is a cross-sectional view showing the extension part of Modification 2 cut along a virtual plane including the central axis. In the stator 30B of Modification 2 shown in FIG. 15, the extending portion 45B is different from the extending portion 45A shown in FIG. The extending portion 45B is an elastic member. The extending portion 45B is, for example, a leaf spring. The extending part 45 </ b> B has a curved part 46. The curved portion 46 is curved toward the radially outer side (the direction away from the central axis Zr) from the side peripheral portion 30a of the stator 30, and is curved toward the radially inner side (a direction approaching the central axis Zr). The curved part 46 is formed by curving the middle part in the direction of the central axis Zr of the extending part 45B. When the stator 30B is fitted into the inner peripheral surface 11d, the bending portion 46 is elastically deformed and approaches the side peripheral portion 30a.

  With the above configuration, when the stator 30B is fitted into the inner peripheral surface 11d, the bending portion 46 is elastically deformed. Thereby, for example, even if the gap H between the side peripheral portion 30a and the inner peripheral surface 11d of the cylindrical housing 11a is larger than the plate thickness of the extending portion 45B due to insufficient processing accuracy. The extending portion 45B is in contact with the inner peripheral surface 11d. And the extending | stretching part 45B gives the force of the radial direction outer side (direction away from the central axis Zr) to the cylindrical housing 11a. Thereby, even if the gap 30 between the side peripheral part 30a and the internal peripheral surface 11d of the cylindrical housing 11a is larger than the plate | board thickness of the extending | stretching part 45B, the stator 30B is self (stator 30B). The possibility that the fixing with the cylindrical housing 11a becomes insufficient can be reduced.

  Further, with the above configuration, the stator 30B can secure a gap H between the side peripheral portion 30a and the inner peripheral surface 11d of the cylindrical housing 11a. Therefore, the stator 30B can reduce the area which contacts the inner peripheral surface 11d of the cylindrical housing 11a in the side peripheral portion 30a. Thereby, the stator 30B can reduce the distortion (deformation) resulting from the external force received from the cylindrical housing 11a. The external force is a force received when the tube housing 11a is press-fitted or shrink-fitted. As a result, the stator 30B can reduce the deterioration of the magnetic characteristics caused by the distortion, specifically, the iron loss of itself (the stator 30B).

  Further, the stator 30B can secure a gap H (realizes a so-called floating structure) without requiring an additional member such as an O-ring, an elastic member, or a resin member. Further, the stator 30B can secure the gap H (realize a so-called floating structure) without requiring the formation of a groove into which the additional member is fitted. Therefore, the stator 30B can secure the gap H with a simpler manufacturing method (realizes a so-called floating structure), and can suppress the manufacturing cost of itself (the stator 30B).

(Modification 3)
FIG. 16 is a perspective view schematically showing an extending portion of Modification 3. In the stator 30C of Modification 3 shown in FIG. 16, the extending portion 45C is different from the extending portion 45B shown in FIG. The extending portion 45C is an elastic member. The extending portion 45C is, for example, a leaf spring. The extending portion 45 </ b> C has a partially curved portion 47. The partially curved portion 47 is configured by notching a part of the extending portion 45C and bending the notched portion. The partial curved portion 47 is curved from the side peripheral portion 30a of the stator 30C toward the radially outer side (the direction away from the central axis Zr) and curved toward the radial inner side (the direction approaching the central axis Zr). When the stator 30C is fitted into the inner peripheral surface 11d shown in FIG. 13, the partially curved portion 47 is elastically deformed and approaches the side peripheral portion 30a.

  With the above configuration, when the stator 30C is fitted into the inner peripheral surface 11d, the partially curved portion 47 is elastically deformed. Thereby, for example, even if the gap H between the side peripheral portion 30a and the inner peripheral surface 11d of the cylindrical housing 11a is larger than the plate thickness of the extending portion 45C due to insufficient processing accuracy. The extending portion 45C is in contact with the inner peripheral surface 11d. The extending portion 45C applies a force radially outward (in a direction away from the central axis Zr) to the cylindrical housing 11a. Thereby, even if the gap 30 between the side peripheral part 30a and the internal peripheral surface 11d of the cylindrical housing 11a is larger than the plate | board thickness of the extending | stretching part 45, the stator 30C is self (stator 30C). The possibility that the fixing with the cylindrical housing 11a becomes insufficient can be reduced.

  Further, with the above configuration, the stator 30C can ensure a gap H between the side peripheral portion 30a and the inner peripheral surface 11d of the cylindrical housing 11a. Therefore, the stator 30C can reduce the area which contacts the inner peripheral surface 11d of the cylindrical housing 11a in the side peripheral portion 30a. Thereby, the stator 30C can reduce the distortion (deformation) resulting from the external force received from the cylindrical housing 11a. The external force is a force received when the tube housing 11a is press-fitted or shrink-fitted. As a result, the stator 30C can reduce the deterioration of the magnetic characteristics due to the strain, specifically the iron loss of itself (the stator 30C).

  Further, the stator 30C can secure the gap H (realizes a so-called floating structure) without requiring an additional member such as an O-ring, an elastic member, or a resin member. Further, the stator 30C can secure the gap H (realizes a so-called floating structure) without requiring the formation of a groove into which the additional member is fitted. Therefore, the stator 30C can secure the gap H with a simpler manufacturing method (realizes a so-called floating structure), and can suppress the manufacturing cost of itself (the stator 30C).

(Embodiment 2)
FIG. 17 is a perspective view schematically showing the split core according to the second embodiment before the bent portion is bent. In the stator 50 of the second embodiment shown in FIG. 17, the shape of the second core piece 52 included in the split core 51 is different from the shape of the second core piece 42 shown in FIG. The second core piece 52 includes a base 43, a first bent portion 54a and a first extended portion 55a, and a second bent portion 54b and a second extended portion 55b. The first bent portion 54a and the second bent portion 54b are formed on the outer side in the radial direction (a part away from the central axis Zr) in the back yoke 43a. That is, the first bent portion 54a and the second bent portion 54b are provided in a portion of the back yoke 43a that faces the inner peripheral surface 11d when the stator 30 is fitted into the cylindrical housing 11a as shown in FIG. It is done. The first extending portion 55a and the second extending portion 55b may have the same configuration as the extending portion 45 shown in FIG. 6, or the extending portion 45A shown in FIG. 14, the extending portion 45B shown in FIG. The same configuration as the extending portion 45C may be used.

  The first bent portion 54a and the second bent portion 54b are provided apart in the circumferential direction. In this embodiment, the 1st bending part 54a is provided in one of the both ends in the circumferential direction of the back yoke 43a. The second bent portion 54b is provided on the other of the both ends in the circumferential direction of the back yoke 43a (one on which the first bent portion 54a is not provided). The first extending portion 55a is provided continuously with the first bent portion 54a. The second extending portion 55b is provided continuously with the second bent portion 54b. Thus, the 2nd core piece 52 has two sets of the combination of a bending part and an extending | stretching part. The second core piece 52 may have three or more combinations. Next, a method for manufacturing the stator 50 will be described.

  First, the stator 50 includes a plurality of first core pieces 41 and a second core piece 52 laminated in the central axis Zr direction. In the present embodiment, one second core piece 52 is provided at each end in the direction of the central axis Zr of the plurality of first core pieces 41 (two in total). Next, in the stator 50, as shown in FIG. 7, the first bent portion 54a and the second bent portion 54b of the second core piece 52 are bent. The second core piece 52 is formed so that the first extending portion 55a and the second extending portion 55b are along the central axis Zr (so that the first extending portion 55a and the second extending portion 55b are closer to the central axis Zr). The bent portion 54a and the second bent portion 54b are bent. The first bent portion 54a and the second bent portion 54b are bent toward the center portion of the split core 51 in the central axis Zr direction. Next, the stator 50 is combined with a plurality of divided cores 51 thus configured.

  Here, the timing at which the first bent portion 54a and the second bent portion 54b are bent is not limited before the plurality of split cores 51 are combined. In this case, in the stator 50, the plurality of split cores 51 are combined before the first bent portion 54a and the second bent portion 54b are bent. In the stator 50, after the plurality of split cores 51 are combined, the first bent portion 54a and the second bent portion 54b are bent in the central axis Zr direction. Thereby, the stator 50 is comprised.

  FIG. 18 is a perspective view schematically showing the split core according to the second embodiment after the bent portion is bent. After the first bent portion 54a and the second bent portion 54b are bent, the stator 50 is joined at the portion Y shown in FIG. 18, that is, the portion where the first extending portion 55a and the second extending portion 55b are adjacent to each other. Adjacent first extending portion 55a and second extending portion 55b are joined by welding such as laser welding or TIG welding. In addition, the adjacent 1st extending | stretching part 55a and the 2nd extending | stretching part 55b do not need to be couple | bonded. Then, as shown in FIG. 13, the stator 50 is fitted into the cylindrical housing 11a by, for example, press-fitting or shrink fitting. At this time, the first extending portion 55a and the second extending portion 55b are interposed between the side peripheral portion 30a of the stator 50 and the inner peripheral surface 11d of the cylindrical housing 11a. Since the first extending portion 55a and the second extending portion 55b are interposed between the side peripheral portion 30a and the inner peripheral surface 11d, the stator 50 can be connected to the side peripheral portion 30a of the stator 50 and the cylindrical housing 11a. A gap H is generated between the peripheral surface 11d. In this way, the stator 50 is attached to the housing 11.

  With the above configuration, the stator 50 can ensure a gap H between the side peripheral portion 30a and the inner peripheral surface 11d of the cylindrical housing 11a. Therefore, the stator 50 can reduce the area which contacts the inner peripheral surface 11d of the cylindrical housing 11a in the side peripheral portion 30a. Thereby, the stator 50 can reduce the distortion (deformation) resulting from the external force received from the cylindrical housing 11a. As a result, the stator 50 can reduce the deterioration of the magnetic characteristics due to the strain, specifically the iron loss of itself (the stator 50). Further, the total area where the plurality of first extending portions 55a and the second extending portion 55b are in contact with the inner peripheral surface 11d is the total area where the plurality of extending portions 45 of the first embodiment shown in FIG. 8 are in contact with the inner peripheral surface 11d. Bigger than. Thereby, the stator 50 can reduce a possibility that fixation with self (stator 50) and the cylindrical housing 11a may become inadequate.

  Further, the stator 50 can integrate the plurality of split cores 51 by connecting the adjacent first extending portion 55a and second extending portion 55b. Here, when integrating a plurality of divided cores, for example, there is a method of welding core pieces adjacent in the circumferential direction (corresponding to the first core piece 41 in the present embodiment). However, in this method, due to thermal degradation due to welding, the iron loss of the stator increases depending on the strength of the welded portion, the position where the welding is performed, and the shape of the electrode used when performing the welding. There is a fear. However, in the stator 50, the adjacent first extending portion 55a and second extending portion 55b are coupled. The first extending portion 55a and the second extending portion 55b are portions that are less likely to affect the iron loss of the stator 50 because the influence depth of thermal deterioration due to welding is smaller than in the conventional case. Therefore, the stator 50 can reduce iron loss. As a result, the stator 50 can reduce the loss torque of the brushless motor.

  Further, the stator 50 can secure the gap H (realize a so-called floating structure) without requiring an additional member such as an O-ring, an elastic member, or a resin member. Further, the stator 50 can secure the gap H (realize a so-called floating structure) without requiring the formation of a groove into which the additional member is fitted. Therefore, the stator 50 can secure the gap H (so-called floating structure) by an easier manufacturing method, and can suppress the manufacturing cost of itself (the stator 50).

(Embodiment 3)
FIG. 19 is an explanatory diagram schematically illustrating a side peripheral portion of the stator core according to the third embodiment. The stator 60 of Embodiment 3 shown in FIG. 19 is characterized in that one divided core 61 has three or more second core pieces 42 shown in FIG. The stator 60 may have three or more second core pieces 52 shown in FIG. 17 instead of the second core pieces 42. The stator 60 has a plurality of second core pieces 42 arranged in the direction of the central axis Zr. For example, in the stator 60, the second core pieces 42 are disposed one at each end of the central axis Zr direction (two in total). In addition, in the stator 60, two second core pieces 42 are arranged between the two second core pieces 42 arranged at both ends. As a result, the stator 60 of the third embodiment has four second core pieces 42. For example, the four second core pieces 42 are arranged at equal intervals in the direction of the central axis Zr.

  Each bent portion 44 is bent in the direction of the central axis Zr. For example, the two second core pieces 42 arranged at both ends are bent at the bent portion 44 toward the middle part in the central axis Zr direction of the stator 60. On the other hand, the two second core pieces 42 arranged in the middle part are bent at the bent portions 44 toward both ends in the direction of the central axis Zr of the stator 60. The direction in which each bent portion 44 is bent may be in the direction of the central axis Zr, and it does not matter whether the bent portion 44 is bent toward both ends of the stator 60 or the middle portion of the stator 60.

  With the above configuration, when the stator 60 is fitted into the cylindrical housing 11a shown in FIG. 13, the four extending portions 45 are interposed between the side peripheral portion 30a and the inner peripheral surface 11d. Thereby, in the stator 60, a gap H is generated between the side peripheral portion 30a and the inner peripheral surface 11d of the cylindrical housing 11a. In this way, the stator 60 can ensure a gap H between the side peripheral portion 30a and the inner peripheral surface 11d of the cylindrical housing 11a. Therefore, the stator 60 can reduce the area which contacts the inner peripheral surface 11d of the cylindrical housing 11a in the side peripheral portion 30a. Thereby, the stator 60 can reduce the distortion (deformation) resulting from the external force received from the cylindrical housing 11a. As a result, the stator 60 can reduce the deterioration of the magnetic characteristics due to the strain, specifically the iron loss of itself (the stator 60).

  Further, the stator 60 has more extending portions 45 than the stator 30 of the first embodiment shown in FIG. Therefore, in the stator 60, the total area where the plurality of extending portions 45 are in contact with the inner peripheral surface 11d is larger than the total area where the plurality of extending portions 45 of the first embodiment shown in FIG. 8 are in contact with the inner peripheral surface 11d. . Thereby, the stator 60 can reduce suitably a possibility that fixation with self (stator 60) and the cylindrical housing 11a may become inadequate.

  Further, the stator 60 can secure the gap H (realize a so-called floating structure) without requiring an additional member such as an O-ring, an elastic member, or a resin member. In addition, the stator 60 can secure the gap H (realize a so-called floating structure) without requiring the formation of a groove into which the additional member is fitted. Therefore, the stator 60 can secure the gap H (so-called floating structure) by an easier manufacturing method, and can suppress the manufacturing cost of itself (the stator 60).

  Each of the above-described stators (30, 30A, 30B, 30C, 50, 60) has a configuration in which an extending portion protrudes from a side peripheral portion of the stator in a direction orthogonal to the central axis Zr so that the gap H can be secured. However, in each stator, the extending portion may not protrude from the side peripheral portion of the stator. Even in this case, each of the stators described above does not require an additional member such as an O-ring, an elastic member, or a resin member. Moreover, each stator mentioned above does not require the formation of a groove into which the additional member is fitted. Therefore, each stator mentioned above can reduce a possibility that the composition of self (stator) may become complicated.

  As described above, the brushless motor stator, the brushless motor and the electric power steering device, and the brushless motor stator manufacturing method according to the present invention are useful for techniques for reducing the risk of the configuration of the brushless motor stator becoming complicated. .

DESCRIPTION OF SYMBOLS 10 Brushless motor 11 Housing 11a Tubular housing 11b Front bracket 11c Bottom part 11d Inner peripheral surface 12, 13 Bearing 14 Resolver 14a Resolver rotor 14b Resolver stator 15 Terminal block 20 Rotor 21 Shaft 22 Rotor core 23 Magnets 30, 30A, 30B, 30C, 50 , 60 Stator 30a Side peripheral portion 31 Stator core 32, 51, 61 Split core 33, 43a Back yoke 34, 43b Teeth 37 Excitation coil 37a Insulator 41 First core piece 41a Guide groove 42 Second core piece 43 Base 44 Bending portion 45, 45A, 45B, 45C Extending portion 46 Bending portion 47 Partial bending portion 52 Second core piece 54a First bent portion 54b Second bent portion 55a First extending portion 55b Second extending portion 80 Electric powers Steering device 81 Steering wheel 82 Steering shaft 82a Input shaft 82b Output shaft 83 Steering force assist mechanism 84, 86 Universal joint 85 Lower shaft 87 Pinion shaft 88 Steering gear 88a Pinion 88b Rack 89 Tie rod 90 ECU
91a Torque sensor 91b Vehicle speed sensor 92 Deceleration device 93 Deceleration device housing 94 Worm 94a Worm tooth 95a, 95b Ball bearing 96 Worm wheel 96a Worm wheel tooth 97 Holder 98 Ignition switch 99 Power supply H, H1 Clearance Zr Central shaft

Claims (8)

A plurality of first core pieces stacked in the central axis direction of the stator core;
One or more second core pieces laminated together with the first core pieces in the central axis direction;
An exciting coil provided in the stator core;
The second core piece includes:
A base in contact with the first core piece;
An extending portion that is continuous with the base portion and extends in the direction of the central axis so as to face the side peripheral portions of the plurality of first core pieces stacked;
A stator for a brushless motor, comprising:   The stator for a brushless motor according to claim 1, wherein a plurality of the second core pieces are arranged in the central axis direction.   3. The brushless motor stator according to claim 1, wherein the extending portion protrudes from the side peripheral portion in a direction orthogonal to the central axis direction. 4. The stator core includes a plurality of split cores arranged in a circumferential direction around the central axis and combined with each other,
The said 2nd core piece is each provided in the said division | segmentation core adjacent in the said circumferential direction, The two said extending | stretching parts adjacent in the said circumferential direction are mutually connected, The Claim 1 to Claim 3 characterized by the above-mentioned. The stator for brushless motors as described in any one of Claims.   The stator for a brushless motor according to claim 4, wherein the second core piece has extending portions at both ends in the circumferential direction. A tubular housing;
The brushless motor stator according to any one of claims 1 to 5, provided inside the cylindrical housing;
A rotor provided to be surrounded by the brushless motor stator;
A brushless motor comprising:   An electric power steering apparatus characterized in that an auxiliary steering torque is obtained by the brushless motor according to claim 6. Laminating a plurality of first core pieces and one or more second core pieces in the central axis direction of the stator core;
A step of bending the second core piece so that extending portions protruding from the plurality of first core pieces of the second core piece are close to the central axis direction;
A stator manufacturing method for a brushless motor, comprising:

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