JP2008011638A - Motor and electric power steering system incorporating the motor - Google Patents

Abstract

There is provided a permanent magnet type motor capable of suppressing deformation of a stator core and reducing cogging torque.
A stator core 1 is fixed to a frame 3, and a rotor disposed in the stator core 1 with a gap includes a permanent magnet, and an axial direction of a cylindrical frame 3 and When the convex portion 4 having a non-uniform thickness is provided in the circumferential direction, the concave portion is formed on the inner peripheral surface of the frame 3 at a position facing the outer peripheral side of the axial end portion of the stator core 1. By providing 9, the stress in this portion can be relaxed.
[Selection] Figure 1

Description

  The present invention relates to a motor having a stator fixed to a frame and an electric power steering system incorporating the motor, and more particularly to a permanent magnet type motor in which a rotor includes a permanent magnet.

  In a permanent magnet motor, torque pulsation called cogging torque is generated when the stator core and the permanent magnet constituting the rotor interact with each other. Since cogging torque causes vibration, reducing cogging torque is a major issue in fields such as industrial servo motors and automobile power steering motors.

  As a conventional technique for reducing the cogging torque, for example, there is a technique in which the magnet is subjected to so-called skew magnetization, in which the boundary between the N pole and the S pole is slanted, or the shape of the segment magnet is made a kamaboko shape. It was. Further, there has been a technique for providing an auxiliary groove in the stator core.

  On the other hand, in order to reduce the cogging torque generated due to a work error, there has been provided a protrusion on the inner peripheral surface of the frame to bring the inner diameter of the stator core closer to a perfect circle (see Patent Document 1).

  In addition, there was a rotating electrical machine in which a gap portion for relaxing stress was provided at a predetermined position of the frame in order to reduce the cogging torque caused by the distortion of the magnetic circuit of the iron core caused by the frame shape (patent) Reference 2).

JP 2005-287191 A JP 2005-80416 A

  In a permanent magnet type motor having a stator fixed to a frame, when the shape of the frame is not uniform in the axial direction or circumferential direction, the stress applied to the stator core is not uniform. Due to this non-uniform stress, the inner periphery of the stator is deformed, and the inner periphery of the stator is no longer a perfect circle, resulting in an increase in cogging torque.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a permanent magnet type motor that can suppress the deformation of the stator core and reduce the cogging torque.

  A motor according to the present invention includes a frame, a stator core fixed to the frame, and a rotor disposed in the stator core via a gap, and the axial end of the stator core This is a position opposed to the outer peripheral side of the part, and is provided with a recess on the inner peripheral surface of the frame.

  The motor according to the present invention includes a frame, a stator core fixed to the frame, and a rotor disposed in the stator core via a gap, and the shaft of the stator core Since the concave portion is provided on the inner peripheral surface of the frame at a position facing the outer peripheral side of the direction end portion, deformation generated in the stator core can be suppressed, and cogging torque can be reduced.

Embodiment 1 FIG.
Embodiments of the present invention will be described below with reference to the drawings.
1 is a side sectional view showing a permanent magnet type motor according to Embodiment 1 of the present invention. The stator core 1 is generally composed of a magnetic material, and is composed of, for example, laminated electromagnetic steel plates or composed of magnetic powder.

  The armature winding 2 is housed in a slot provided in the stator core 1. In FIG. 1, only the coil end portion of the armature winding 2 is shown. Although not shown, a rotor is provided in the stator core 1 coaxially with the stator core 1 via a gap, and the rotor includes a permanent magnet and a bearing. Is supported by

  The frame 3 in which the stator core 1 is incorporated is made of aluminum, iron, or the like, and is generally formed in a cylindrical shape. On the other hand, the thickness of the frame 3 may be formed to be nonuniform according to various product specifications. In FIG. 1, an example in which the convex portion 4 having an increased thickness is provided at the upper end portion of the frame 3 is shown.

  2 to 5 are perspective views of the frame 3 showing a case where the convex portion 4 is provided at one end of the outer peripheral surface of the frame 3, and in FIG. 2, screw holes for fixing the frame 3 to other parts and the like. The convex part 4 provided with 5 is installed. Further, FIG. 3 shows a case where a joint portion 6 with other parts (for example, a controller of a motor) is provided in the frame 3.

  FIG. 4 shows a case where the cooling fins 7 are provided on the frame 3. Furthermore, in FIG. 5, the case where the thick part 8 is provided in the flame | frame 3 is shown. All of the examples shown in FIGS. 2 to 5 show cases where the thickness of the frame 3 is not constant.

  The stator core 1 is fixed inside the frame 3 by shrink fitting or press fitting. If the thickness of the frame 3 is not uniform in the circumferential direction and the axial direction as described above, the stator core 1 is fixed. The stress applied to the core 1 becomes non-uniform, the magnetic characteristics of the stator core 1 become non-uniform, or the inner peripheral shape of the stator core 1 is deformed. As a result, the cogging torque increases.

  Therefore, in the present invention, the concave portion 9 is provided on the inner peripheral surface of the frame 3 in order to suppress the influence of the convex portion 4 provided on the frame 3. Although FIG. 1 shows a case where the tapered concave portion 9 is provided, the concave portion 9 may have a step shape or another shape. The concave portion 9 for suppressing the deformation of the frame 3 by the convex portion 4 is provided at a position facing the outer peripheral side of the axial end portion of the stator core 1. Even when the convex portion 4 is provided near the middle of the frame 3, the concave portion 9 is provided at a position facing the outer peripheral side of the axial end portion of the stator core 1.

  The concave portion 9 is provided at a position facing the outer peripheral side of the axial end portion of the stator core 1 in this manner when a radial force is applied to the end portion of the hollow cylindrical stator core 1. This is because even if the force is very small, the cylinder itself is more likely to deform the barrel (bulging), and this force is avoided from being transmitted from the frame 3 to the cylindrical stator core 1.

  FIG. 6 is a front sectional view taken along line AA in FIG. 1, and a convex portion 4 is provided on a part of the frame 3. Further, a recess 9 for suppressing deformation is provided on the inner peripheral surface of the frame 3 at a position facing the protrusion 4.

  When the concave portion 9 is not provided as in the prior art, the stress of this portion is increased due to the influence of the convex portion 4 of the frame 3 and the inner peripheral shape of the stator core 1 is deformed, and the cogging torque is increased. That happened. However, since the concave portion 9 is provided in the present invention, the stress in this portion is relieved, and therefore deformation of the inner peripheral shape of the stator core 1 is suppressed, and as a result, cogging torque can be reduced.

  In FIG. 6, the circumferential length of the concave portion 9 is substantially the same as the circumferential length of the convex portion 4, but the circumferential length of the concave portion 9 is larger than the circumferential length of the convex portion 4. You may comprise so that it may become large, Furthermore, you may comprise so that the length of the circumferential direction of the recessed part 9 may become smaller than the length of the circumferential direction of the convex part 4. FIG.

  Moreover, you may comprise so that the depth of the recessed part 9 may become very small compared with the thickness of the convex part 4. FIG. By providing the recess 9 over a part of the inner periphery rather than over the entire inner periphery, the number of processing steps can be reduced, and the processing cost can be reduced.

  FIG. 7 is a front cross-sectional view showing another example. As shown in FIG. 7, the concave portion 9 can be formed so as to have a shape along a circular arc eccentric from the center of the frame 3. That is, as shown in FIG. 6, the inner peripheral surface of the frame 3 and the concave portion 9 are configured to be smoothly connected in an arc shape so that no step is generated at the joint portion between the inner peripheral surface of the frame 3 and the concave portion 9. Is. In this case, there is an effect that cutting is easy and the productivity is excellent.

  Next, how the cogging torque is specifically reduced by providing the recess will be described with reference to the drawings. FIG. 8 is a perspective view showing the shape of the frame, and the joint portion 6 is provided in the frame 3 as in the case shown in FIG.

  A stator core 1 is fixed in the frame 3 by shrink fitting or press fitting, and both axial ends of the stator core 1 are located at positions corresponding to the upper part 3a and the lower part 3c of the frame 3, respectively. Yes. The intermediate portion 3b is located in the middle of the frame 3 in the axial direction.

  9 is a side sectional view taken along line BB in FIG. A joint 6 with other parts is provided near the lower part 3c of the frame 3, and the thickness of the frame 3 is increased in this part. 10 is a front sectional view of the upper part 3a, FIG. 11 is a front sectional view of the lower part 3c, and a front sectional view of the middle part 3b is the same as FIG.

  In the figure, the stator core 1 shows an example of concentrated winding of 12 slots, but may have other numbers of slots or distributed winding. Further, the stator core 1 may be a split core or an integrally punched core, and may further be formed of magnetic powder.

  In FIG. 11, a recess 9 for suppressing deformation is provided at a position corresponding to the joint 6 with another component. However, when the recess 9 is not provided as in the prior art, this portion As the stress increases, the shape of the inner diameter of the stator core 1 is distorted.

  FIG. 12 is a diagram showing a state of distortion of the inner peripheral shape in the conventional stator core 1. In the present invention, the provision of the concave portion 9 reduces the influence of the convex portion 4 (here, the joint portion 6 with other components) as shown in FIG. Circularity is improving.

  FIG. 14 is a diagram showing a state of distortion of the inner peripheral shape in each of the upper portion 3a, the middle portion 3b, and the lower portion 3c of the stator core 1 when the concave portion 9 is not provided as in the related art. It can be seen that the degree of distortion of the shape is greatly different and is not uniform in the axial direction.

  FIG. 15 is a diagram showing a state of distortion of the inner peripheral shape in each of the upper part 3a, the middle part 3b, and the lower part 3c of the stator core 1 when the concave part 9 is provided. As shown in FIG. 15, the concave part 9 is provided. Thus, it can be seen that the roundness of the inner peripheral shape of the stator core 1 is improved and the non-uniformity in the axial direction is improved.

  FIG. 16 is a diagram showing the relationship between the rotation angle and the cogging torque in the prior art and the present invention, where the solid line indicates the prior art and the dotted line indicates the characteristics of the present invention. As shown in FIG. 16, it can be seen that the cogging torque can be reduced by providing the recess 9. The frequency component of the cogging torque generated by the asymmetry of the stator core 1 mainly includes a component in which the number of pulsations per rotation of the rotor matches the number of poles of the motor.

  When a component having an electrical angle of 360 degrees is used as a fundamental wave, this becomes a second harmonic component and may be called a 2f component. FIG. 16 shows an example of a 10-pole motor, and a component that pulsates 10 times with one rotation of the rotor (0 to 360 degrees on the horizontal axis in the figure) can be seen. It can be seen that this is greatly reduced in the present invention compared to the conventional example. That is, the present invention has an effect of reducing the 2f component of the cogging torque.

  As described above, according to the present invention, since the concave portion 9 is provided on the inner peripheral surface of the frame 3 at a position facing the outer peripheral side of the axial end portion of the stator core 1, the outer periphery of the frame 3 is provided according to the product specifications. Even when the convex portion 4 is provided, the deformation that occurs on the inner periphery of the stator core 1 can be suppressed by providing a relatively small concave portion 9 with respect to the convex portion 4. As a result, the circularity of the inner circumference of the stator core 1 is improved, and there is an effect that the cogging torque generated in the permanent magnet type motor can be reduced.

  In the above, the convex part 4 is provided in the outer peripheral part of the frame 3, and in order to avoid the non-uniform stress acting on the stator core 1, thereby, the outer peripheral side of the axial end part of the stator core 1 is provided. The case where the concave portion 9 smaller than the convex portion 4 is provided at a part of the inner peripheral surface of the frame 3 in the circumferential direction has been described. In order to avoid non-uniform stress acting on the stator core 1, a convex portion smaller than the concave portion may be provided on the inner peripheral surface of the frame 3. In addition, the cogging torque can be reduced.

  FIG. 17 is a side sectional view showing a permanent magnet type motor according to a form different from that in FIG. 1, in which a recess 10 is provided in the outer peripheral portion of the frame 3, and the outer peripheral side of the axial end portion of the stator core 1. The convex portion 11 is provided on the inner peripheral portion of the frame 3 facing the end portion opposite to the end portion where the concave portion 10 is provided. In addition, it is necessary to provide the convex part 11 in the part located just under the recessed part 10, Furthermore, the length of the circumferential direction of the convex part 11 may be substantially the same as the circumferential direction length of the recessed part 10, and it is larger. You may comprise, and you may comprise small. By comprising in this way, it can avoid that a non-uniform stress acts on the stator core 1. FIG.

Embodiment 2. FIG.
18 is a side sectional view showing a permanent magnet type motor according to Embodiment 2 of the present invention, and FIG. 19 is a sectional view taken along line CC in FIG. The stator core 1 is generally composed of a magnetic material, and is composed of, for example, laminated electromagnetic steel plates or composed of magnetic powder.

  The armature winding 2 is housed in a slot provided in the stator core 1. In FIG. 18, only the coil end portion of the armature winding 2 is shown. Although not shown, a rotor is provided in the stator core 1 coaxially with the stator core 1 via a gap, and the rotor includes a permanent magnet and a bearing. Is supported by

  The frame 3 in which the stator core 1 is incorporated is made of aluminum, iron, or the like, and is generally formed in a cylindrical shape. On the other hand, the thickness of the frame 3 may be formed to be nonuniform according to various product specifications. FIG. 18 shows an example in which the convex portion 4 having an increased thickness is provided at a position corresponding to the upper end portion of the stator core 1.

  In the prior art, there is a problem that the stress in the convex portion 4 increases, the stator core 1 may be deformed inward, and the cogging torque increases. Moreover, since stress becomes non-uniform in the axial direction, there is a problem that the inner peripheral shape of the stator core 1 is also non-uniform in the axial direction.

  In the outer peripheral surface of the frame 3 in the present embodiment, a convex portion 21 is provided at a portion facing the outer peripheral side of the lower end portion in the axial direction of the stator core 1 and located immediately below the convex portion 4. is there. Although this convex portion 21 is smaller than the convex portion 4 provided at a position corresponding to the upper end portion of the stator core 1, the unevenness in the axial direction of stress applied to the stator core 1 can be reduced. Even when the convex portion 4 is provided near the middle of the frame 3, the convex portion 21 is provided at a position facing the outer peripheral side of the axial end portion of the stator core 1.

  The convex portion 21 is provided at a position facing the outer peripheral side of the lower end portion in the axial direction of the stator core 1 in this way, for example, when a radial force is applied to the end portion of the hollow cylindrical stator core 1. This is because even if this force is very small, the cylinder itself is more likely to deform the barrel (bulging), and this force is prevented from being transmitted from the frame 3 to the cylindrical stator core 1. .

  The convex portion 21 is provided in a part of the circumferential direction, and the circumferential length of the convex portion 21 may be substantially the same as the circumferential length of the convex portion 4 or may be configured to be larger. It may be configured small.

  As described above, according to the present embodiment, it is possible to suppress deformation of the inner periphery of the stator core 1 by providing the convex portion 21 that is smaller than the convex portion 4. As a result, the roundness of the inner periphery of the stator core 1 is improved, and the cogging torque generated in the permanent magnet type motor can be reduced.

Embodiment 3 FIG.
20 is a side sectional view showing a permanent magnet type motor according to Embodiment 3 of the present invention.
The stator core 1 is generally composed of a magnetic material, and is composed of, for example, laminated electromagnetic steel plates or composed of magnetic powder.

  The armature winding 2 is housed in a slot provided in the stator core 1. In FIG. 20, only the coil end portion of the armature winding 2 is shown. Although not shown, a rotor is provided in the stator core 1 coaxially with the stator core 1 via a gap, and the rotor includes a permanent magnet and a bearing. Is supported by

  The frame 3 in which the stator core 1 is incorporated is made of aluminum, iron, or the like, and is generally formed in a cylindrical shape. On the other hand, the thickness of the frame 3 may be formed to be nonuniform according to various product specifications. In FIG. 20, an example is shown in which the convex portion 31 having an increased thickness is provided at a position facing the outer peripheral side of the lower end portion in the axial direction of the stator core 1.

  In the prior art, there is a problem that the stress in the convex portion 31 is increased, the stator core 1 may be deformed inward, and the cogging torque is increased. Moreover, since stress becomes non-uniform in the axial direction, there is a problem that the inner peripheral shape of the stator core 1 is also non-uniform in the axial direction.

  In the present embodiment, a concave portion 32 is provided in the vicinity of the lower end portion in the axial direction of the stator core 1 and at a position facing the convex portion 31. That is, the outer diameter of the lower end portion of the stator core 1 is reduced, and a space is provided between the stator core 1 and the frame 3. Although the depth of the concave portion 32 is smaller than the height of the convex portion 31 provided at the lower portion of the stator core 1, by providing the concave portion 32, the non-uniformity of stress in the axial direction can be reduced. . Even when the convex portion 31 is provided near the middle of the frame 3, the concave portion 32 is provided at the lower end portion of the stator core 1.

  Thus, by providing the concave portion 32 on the outer peripheral surface of the stator core 1, it is possible to avoid that stress is transmitted from the frame 3 to the stator core 1. The length in the circumferential direction of the concave portion 32 may be substantially the same as the length in the circumferential direction of the convex portion 31, or may be configured to be larger or smaller.

  As described above, according to the present embodiment, it is possible to prevent the inner periphery of the stator core 1 from being deformed by providing the concave portion 32 that is smaller than the convex portion 31. As a result, the roundness of the inner circumference of the stator core 1 is improved, and the cogging torque generated in the permanent magnet type motor can be reduced.

Embodiment 4 FIG.
FIG. 21 is a side sectional view showing a permanent magnet type motor according to Embodiment 4 of the present invention.
The stator core 1 is generally composed of a magnetic material, and is composed of, for example, laminated electromagnetic steel plates or composed of magnetic powder.

  The armature winding 2 is housed in a slot provided in the stator core 1. In FIG. 21, only the coil end portion of the armature winding 2 is shown. Although not shown, a rotor is provided in the stator core 1 coaxially with the stator core 1 via a gap, and the rotor includes a permanent magnet and a bearing. Is supported by

  The frame 3 in which the stator core 1 is incorporated is made of aluminum, iron, or the like, and is generally formed in a cylindrical shape. However, a uniform compressive force may not always be applied from the frame 3 to the stator core 1 in order to meet various product specifications, or due to a difference in finishing work and a self-load when a permanent magnet type motor is installed.

  For this reason, the roundness of the inner peripheral shape of the stator core 1 may be lost, thereby increasing the cogging torque, resulting in a problem that a high-performance permanent magnet motor cannot be obtained.

  Therefore, in the present embodiment, a tapered concave portion 41 is provided on the inner peripheral side of the frame 3 at a position facing the outer peripheral side of both axial end portions of the stator core 1. Thereby, even when a uniform compressive force from the frame 3 to the stator core 1 does not act, the roundness of the inner peripheral portion of the stator core 1 can be maintained, and an increase in cogging torque can be prevented. The shape of the recess 41 is not limited to a tapered shape, and may be another shape such as a step shape.

  The recess 41 may be provided over the entire circumference of the inner periphery of the frame 3 or may be provided in part. The concave portion 41 may be provided only at a position facing the outer peripheral side of one axial end portion of the stator core 1.

  As described above, according to the present embodiment, even when the convex portion 31 as shown in FIG. 20 is not clearly present, it can be adapted to various product specifications, or a slight difference in finishing work can be caused. Preventing deformation from occurring on the inner periphery of the stator core 1 even when a uniform compressive force does not act from the frame 3 to the stator core 1 by generating a self-load when the magnet type motor is installed. Can do.

  As a result, the roundness of the inner circumference of the stator core 1 is improved, and the cogging torque generated in the permanent magnet type motor can be reduced. Furthermore, when the stator core 1 is configured by laminating electromagnetic steel sheets, even when there is a variation during lamination, the distortion generated in the entire armature core can be suppressed by providing the recess 41, so that the cogging torque can be reduced. Generation can be reduced.

Embodiment 5 FIG.
Since the permanent magnet type motors shown in the first to fourth embodiments can reduce the cogging torque, they can be used for industrial servo motors, automotive electric power steering systems, and the like. In this embodiment, an example in which the permanent magnet type motor shown in the first to fourth embodiments is applied to an electric power steering system for an automobile will be described.

  FIG. 22 is a conceptual diagram showing an electric power steering system for automobiles. In the figure, human steering force is transmitted from a steering wheel 51 to a column shaft 52. The worm gear 53 (details are omitted in the figure, only the gear box is shown) transmits the output (torque, rotation speed) of the motor 54 while changing the rotation direction to a right angle, and simultaneously decelerates to increase the assist torque. .

  The handle joint 55 transmits a steering force and changes its direction. A steering gear 56 (details are omitted in the figure, only the gearbox is shown) decelerates the rotation of the column shaft 52, and at the same time, the rotational force is converted into a linear motion of the rack 57 to obtain a required transition. The wheels are moved by the linear motion of the rack 57, and the direction of the vehicle can be changed.

  In the electric power steering system as described above, torque pulsation generated in the motor 54 is transmitted to the steering wheel 51 via the worm gear 53 and the column shaft 52. Therefore, when the motor 54 generates a large torque pulsation, a smooth steering feeling cannot be obtained.

  Even when the motor 54 does not generate assisting torque, a smooth steering sensation cannot be obtained if the motor 54 generates a large cogging torque.

  The motor 54 used in the electric power steering system needs to reduce the cogging torque as described above, but at the same time, since it is used for automobiles, it is desired to reduce the size, reduce the weight, increase the efficiency, and increase the output. It is. In order to overcome such a problem, the motor 54 is preferably configured integrally with the controller.

  This is because the installation space can be reduced by integrating the motor 54 with the controller, and the size and weight can be reduced. In addition, when the motor and the controller are separated as in the prior art, power loss has occurred in the harness (power cable) between the motor and the controller, resulting in poor efficiency and output loss. However, when the motor and the controller are integrated, there is an advantage that such a loss does not occur.

  FIG. 23 is a side view showing a state in which the motor and the controller are integrated. The permanent magnet type motor 54 is joined to the controller 58 through a joint portion 6 with the controller provided in the frame 3. In such a case, the frame 3 of the motor 54 has a portion where the thickness becomes non-uniform corresponding to the product specifications.

  23 shows the projection 6 provided with the joint 6 with the frame shown in FIG. 3 and the screw hole 5 shown in FIG. 2, but for improving the cooling performance as shown in FIG. A cooling fin 7 or the like may be provided.

  The motor 54 integrally formed with the controller 58 can be reduced in size, weight, efficiency, and output, but since the joint 6 is provided, the thickness of the frame 3 is axial and circumferential. , The stress acting on the stator core 1 from the frame 3 is also non-uniform. As a result, the roundness of the inner peripheral shape of the stator core 1 is deteriorated, and the cogging torque is increased.

  Therefore, in such a permanent magnet type motor 54 used in the electric power steering system for automobiles, as shown in FIGS. 1 and 18, the frame 3 is provided with the concave portion 9 or the convex portion 21, and further shown in FIG. As described above, by providing the concave portion 32 in the stator core 1, even when the convex portion is provided on the outer periphery of the frame 3 in accordance with the product specifications, as described in the first to third embodiments, the stator core The deformation | transformation which generate | occur | produces in the inner periphery of 1 can be suppressed.

  As a result, the roundness of the inner periphery of the stator core 1 is improved, and the cogging torque generated in the permanent magnet type motor 54 can be reduced. Furthermore, in the permanent magnet motor 54, as shown in FIG. 21, by providing a tapered recess 41 on the inner peripheral surface of the frame 3, even when a uniform compressive force does not act from the frame 3 to the stator core 1, The roundness in the inner peripheral portion of the stator core 1 can be maintained, and an increase in coking torque can be prevented.

  Therefore, according to the present embodiment, since the cogging torque generated in the permanent magnet type motor 54 can be reduced, there is an effect that the steering feeling in the electric power steering system for automobiles can be improved. 22 and 23, the column type electric power steering system has been described. However, the present invention is not limited to this, and the same effect can be obtained even if the above configuration is adopted in the rack type electric power steering system. Needless to say.

It is side surface sectional drawing which shows the permanent magnet type motor by Embodiment 1 of this invention. It is a perspective view which shows a flame | frame. It is a perspective view which shows a flame | frame. It is a perspective view which shows a flame | frame. It is a perspective view which shows a flame | frame. FIG. 2 is a front sectional view taken along line AA in FIG. 1. It is front sectional drawing which shows a flame | frame. It is a perspective view which shows a flame | frame. It is a BB line side surface sectional view in Drawing 8. It is front sectional drawing which shows a permanent magnet type | mold motor. It is front sectional drawing which shows a permanent magnet type | mold motor. It is a figure which shows the deformation | transformation of the conventional stator core. It is a figure which shows the deformation | transformation of the stator core by this invention. It is a figure which shows the deformation | transformation of the conventional stator core. It is a figure which shows the deformation | transformation of the stator core by this invention. It is a figure which shows the relationship between a rotation angle and the magnitude | size of cogging torque. It is side surface sectional drawing which shows a permanent magnet type | mold motor. It is side surface sectional drawing which shows the permanent magnet type motor by Embodiment 2 of this invention. It is CC sectional view taken on the line in FIG. It is side surface sectional drawing which shows the permanent magnet type motor by Embodiment 3 of this invention. It is side surface sectional drawing which shows the permanent magnet type motor by Embodiment 4 of this invention. It is a conceptual diagram which shows the electric power steering system for motor vehicles. It is a side view which shows the motor united with the controller.

Explanation of symbols

  1 Stator core, 3 frames, 9, 32, 41 concave, 21 convex.

Claims (9)

In a motor having a frame, a stator core fixed to the frame, and a rotor disposed in the stator core via a gap, a position facing the outer peripheral side of the axial end of the stator core A motor characterized in that a recess is provided on the inner peripheral surface of the frame. The motor according to claim 1, wherein the inner peripheral surface of the frame and the recess are connected in an arc shape. The motor according to claim 1, wherein the recess is provided in a part of a circumferential direction of the frame. In a motor having a frame, a stator core fixed to the frame, and a rotor disposed in the stator core via a gap, a position facing the outer peripheral side of the axial end of the stator core A motor characterized in that a tapered recess is provided on the inner peripheral surface of the frame. The motor according to claim 4, wherein the tapered recess is provided in a part of a circumferential direction of the frame. In a motor having a frame, a stator core fixed to the frame, and a rotor disposed in the stator core via a gap, a position facing the outer peripheral side of the axial end of the stator core The motor is characterized in that a convex portion is provided on the outer peripheral surface of the frame. The motor according to claim 6, wherein the convex portion is provided at a part of the frame in the circumferential direction. In a motor having a frame, a stator core fixed to the frame, and a rotor disposed in the stator core via a gap, a recess is provided on the outer peripheral surface of the axial end of the stator core. A motor characterized by that. An electric power steering system using the power of the motor according to any one of claims 1 to 8 as a steering force.

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