JP5988951B2 - Permanent magnet type rotating electrical machine and method for manufacturing permanent magnet type rotating electrical machine - Google Patents

Description

  The present invention relates to a permanent magnet type rotating electrical machine and a method for manufacturing a permanent magnet type rotating electrical machine.

  In a permanent magnet type rotating electrical machine used in various applications in recent years, in order to fix a stator core and a frame that houses the stator core, a method of fixing the frame by shrink fitting is generally used. Further, in motors for electric power steering, servos, elevators, etc., there is a demand for a motor having a small cogging torque and a small torque pulsation under load.

  Therefore, a convex part is formed on the outer surface of the stator core or the inner side surface of the frame, and the core is supported inside the frame through the convex part, and the magnetic characteristics are deteriorated due to stress during shrink fitting. Cogging torque pulsation due to non-uniform magnetic flux density caused by coherent torque pulsation and cogging torque pulsation due to the original stator core shape are prevented from matching to keep cogging torque pulsation low There has been proposed a method (for example, Patent Document 1).

JP 2009-95184 A

  In the invention according to Patent Document 1, the frame is shrink-fitted into the stator core in order to fix the stator core and the frame. In order to shrink-fit the frame, a step of heating the frame, a step of inserting the stator core, and a step of cooling the rotating electric machine are required. Thus, time for heating and cooling is required. However, since it is necessary to heat and cool the entire frame, there is a problem that it takes longer time for heating and cooling as the frame becomes larger. Moreover, in order to perform shrink fitting, a heating furnace such as a high-frequency heating device is required, and there is a problem that a large amount of capital investment is required.

  The present invention has been made to solve the above-described problems, and is more economical than shrink fitting a frame, and can reduce cogging torque and suppress torque pulsation. It is an object of the present invention to provide a permanent magnet type rotating electrical machine that employs a core and frame fixing method and a method for manufacturing the permanent magnet type rotating electrical machine.

The permanent magnet type rotating electrical machine according to this invention is:
A cylindrical stator core wound around the magnetic pole teeth;
A cylindrical permanent magnet type rotor core having a shaft inserted therein and rotating inside the stator core;
In a permanent magnet type rotating electrical machine having a frame for housing the stator core,
The frame has an inner diameter greater than the outer diameter of the stator core;
There is no seam in the circumferential direction of the outer peripheral surface,
In the axial direction of the shaft, a melted portion melted in a range not penetrating the frame from one end portion to the other end portion of the outer peripheral surface is provided.

The manufacturing method of the permanent magnet type rotating electrical machine according to the present invention is:
A cylindrical stator core wound around the magnetic pole teeth;
A cylindrical permanent magnet type rotor core having a shaft inserted therein and rotating inside the stator core;
In the method of manufacturing a permanent magnet type rotating electrical machine having a frame that houses the stator core,
A stator core insertion step of inserting the stator core into the frame having an inner diameter larger than the outer diameter of the stator core and seamless in the circumferential direction of the outer peripheral surface;
A melting step of melting the outer peripheral surface of the frame in the axial direction of the shaft from one end portion to the other end portion of the outer peripheral surface in a range not penetrating a part of the frame;
After melting by the melting step, the inner peripheral surface of the frame and the outer peripheral surface of the stator core are fixed by contraction force in the outer peripheral direction of the frame generated in the melting portion of the frame due to thermal strain during cooling. A fixing step.

  According to the permanent magnet type rotating electrical machine and the manufacturing method of the permanent magnet type rotating electrical machine according to the present invention, the stator core originally has by deforming the stator core following the contraction of the frame after the frame is melted. By generating a magnetic characteristic that cancels the magnetic characteristic that generates the cogging torque, the cogging torque of the rotating electrical machine can be reduced and torque pulsation can be suppressed. Moreover, since the time required for heating and cooling can be reduced as compared with the case where the entire frame is heated and cooled, the productivity of the product can be improved. In addition, since an inexpensive TIG welding machine or the like can be used to melt the frame, capital investment can be suppressed as compared with a heating furnace such as a high-frequency heating device.

It is sectional drawing before and behind frame deformation | transformation of the permanent magnet type rotary electric machine which concerns on Embodiment 1 of this invention. It is sectional drawing which cut | disconnected the rotary electric machine of FIG. 1 by the plane which passes along the central axis of a shaft. It is a figure which shows the range of the fusion | melting part of the flame | frame of the permanent magnet type rotary electric machine which concerns on Embodiment 1 of this invention. It is sectional drawing of the permanent magnet type rotary electric machine which provided the fusion | melting part in all four surfaces of the outer periphery of a flame | frame. It is a figure which shows the waveform of the 20th-order component of the cogging torque generate | occur | produced when not using the manufacturing method of the permanent magnet type rotary electric machine which concerns on Embodiment 1 of this invention, and the waveform of the sum total of a cogging torque. It is sectional drawing before the deformation | transformation of the flame | frame of the permanent magnet type rotary electric machine which concerns on Embodiment 2 of this invention. It is sectional drawing before the deformation | transformation of the flame | frame of the permanent magnet type rotary electric machine which concerns on Embodiment 3 of this invention.

Embodiment 1 FIG.
Embodiment 1 of the present invention will be described below with reference to the drawings.
FIG. 1 is a cross-sectional view of a permanent magnet type rotating electrical machine 100 (hereinafter simply referred to as a rotating electrical machine 100) according to the present embodiment cut perpendicularly to the axial direction of the shaft 3, and FIG. 5 shows a state before the stator core 21 is fixed, and FIG. 1B shows a state after the fixing.
FIG. 2 is a cross-sectional view of the rotating electrical machine 100 of FIG. 1 cut along a plane that passes through the central axis of the shaft 3.

  First, the configuration of the rotating electrical machine 100 will be briefly described. As shown in FIGS. 1 (a), 1 (b), and 2, the cylindrical stator core 21 including the yoke portion 21a and the magnetic pole tooth portion 21b is formed by laminating thin magnetic plates, and the yoke portion Twelve magnetic pole teeth portions 21b protrude inward from the inner peripheral side of 21a, and slots 7 are formed between adjacent magnetic pole teeth portions 21b. A winding 1 is provided around the magnetic pole teeth portion 21b, and these members constitute the stator 2.

  The cylindrical rotor core 41 inserted into the stator core 21 and rotating is also configured by laminating magnetic plates. The shaft 3 is press-fitted into the center of the rotor core 41. The rotor 4 is composed of the rotor core 41, the permanent magnet 42 disposed on the outer peripheral surface of the rotor core 41, and the permanent magnet 42 having different polarities at equal intervals in the circumferential direction of the rotor core 41. .

  The inner diameter of the frame 5 that accommodates and fixes the stator core 21 inside is configured to be slightly larger than the outer diameter of the stator core 21. The frame 5 has a quadrangular outer peripheral shape when cut perpendicular to the axial direction of the shaft 3, and the inner peripheral shape in the cross section is circular. The frame 5 has no seam in the circumferential direction of the outer peripheral surface 55. FIGS. 1A and 2 both show the state before the stator core 21 and the frame 5 are fixed. In practice, however, as shown in FIG. After the stator core 21 and the frame 5 are fixed to each other, the rotor 4 is inserted into the stator 2.

  A gap 9 is provided between the outer periphery of the rotor core 41 and the inner peripheral surface of the stator core 21, and a magnetic flux is generated by the permanent magnet 42 in the gap 9. The rotor 4 is rotated along the inner peripheral surface of the stator 2 by the rotational torque generated by the action of the magnetic flux generated by the permanent magnet 42 and the magnetic flux generated by the winding 1.

Next, a method for fixing the frame 5 and the stator core 21 by the method for manufacturing a rotating electrical machine according to the present invention will be described. As shown in FIG. 1, a gap 10 is provided between the stator core 21 and the frame 5, and the stator core 21 can be easily accommodated in the frame 5 during assembly (insertion process). ). By the way, when the rotor 4 of the rotating electrical machine 100 rotates, the stator 2 receives a reaction force of the rotational torque of the rotor 4. In order to prevent the stator core 21 from rotating with respect to the frame 5 due to the gap 10, it is necessary to fix the frame 5 and the stator core 21. In the present invention, as a fixing method, a part of the frame 5 is melted by a welding machine (melting step).
The frame 5 and the stator core 21 are fixed using the contraction of the frame 5 caused by the thermal strain after the frame 5 is melted in the melting process (fixing process).

FIG. 3 is a side view showing the range of the melting part of the rotating electrical machine 100.
In the melting step, the central portion of one of the four outer peripheral surfaces 55 of the frame 5 is melted in the axial direction of the shaft 3 by the welding machine 11 from the one end portion 52 toward the other end portion 53. At this time, the depth at which the melting part 51 of the frame 5 is melted is such that it does not penetrate the inner peripheral surface of the frame 5 as shown in FIG.

  The arrows in FIGS. 1 and 3 indicate the direction of the force applied to the frame 5 when the frame 5 is melted. That is, after the melted portion 51 is melted, when the portion is cooled in the fixing process, it is compressed in the direction indicated by the arrow in FIG. 1 (the direction perpendicular to the shaft 3 and parallel to the outer peripheral surface 55). Thermal stress works and the melted part 51 vicinity shrinks. As a result, the inner peripheral surface of the frame 5 contacts the outer peripheral surface of the stator core 21, and the stator core 21 is fixed in the frame 5.

  As a melting method by the welding machine 11, as shown in FIG. 3, a method in which heat is continuously input in the axial direction from one end portion 52 of the frame 5 so as to overlap and a melt is spotted, and although not shown, one spot is spotted. There is a method of melting several places at a certain distance after completely melting. In the case of the continuous melting method, the frame 5 can be uniformly heat-shrinked in the axial direction, but the frame 5 may be excessively melted. In that case, a method of melting several spots at a spot may be used.

Next, the relationship between the amount of heat input and the amount of contraction of the frame 5 will be described. The amount of shrinkage due to thermal strain of the frame 5 is proportional to the amount of heat input from the energy source when the frame 5 is melted by the welder 11. The amount of contraction of the frame 5 can be controlled by adjusting the amount of heat input. The amount of shrinkage is the welding heat input Q (J / mm), the thickness h (mm) of the base plate (frame 5), the material linear expansion coefficient α (1 / ° C), the density ρ (g / mm3), and the specific heat. It is determined by c (J / g ° C.) and is represented by the following formula.
Shrinkage S (mm) = αQ / cρh
From this equation, it can be seen that the shrinkage S is proportional to the welding heat input Q.
When the amount of heat input from the welding machine 11 is increased and the amount of contraction is increased in proportion thereto, the frame 5 is further deformed from the state in which the inner periphery of the frame 5 and the outer periphery of the stator core 21 are in contact with each other, and the stator core 21 Is deformed and fixed following the deformation of the frame 5.

  Next, the cogging torque will be described. The cogging torque of the 10-pole 12-slot permanent magnet type rotating electrical machine 100 includes a component of the number of poles (a component of 10 peaks per rotation of the rotor) and a component of the least common multiple of the number of poles and the number of slots (1 of the rotor). 60 components per revolution). In particular, the 20th-order component (a component of 20 peaks per rotation of the rotor) is generated due to the poor inner diameter machining accuracy of the stator core 21 and the non-uniform magnetic characteristics of the stator core 21. It is difficult to remove in this manufacturing method.

  In the rotating electrical machine 100 according to the present invention, the stator core 21 is deformed into a shape approaching a quadrangle, thereby causing a change in the magnetic characteristics generated in the stator core 21, and the cogging torque originally possessed by the rotating electrical machine 100 before deformation. 20th order components (hereinafter simply referred to as 20th order components) can be generated. That is, the 20th order is a multiple of 4. Therefore, when the stator core 21 is brought close to a quadrangle, a twentieth component is generated. By intentionally generating a 20th-order component that cancels the 20th-order component originally possessed by the rotating electrical machine 100 by adjusting the melting point of the frame, the sum of the 20th-order components of the cogging torque is reduced. Stable operation can be obtained.

  When the melting part 51 of the frame 5 is melted, the frame 5 and the stator core 21 are not fixed in advance with a jig or the like so that the relative positional relationship between the frame 5 and the stator core 21 can be adjusted. By adjusting the relative positional relationship between the two members, the deformation amount of the stator core 21 can be adjusted even with the same amount of heat input. For example, in FIG. 1, the stator core 21 closest to the melting part 51 does not have the magnetic pole tooth part 21 b, but the position of the magnetic tooth part 21 b is shifted by rotating the position of this part. And so on.

  As described above, the central portion of one of the four outer peripheral surfaces 55 of the frame 5 is melted in the axial direction by welding, and is perpendicular to the shaft 3 generated by the thermal strain after melting and is formed on the outer peripheral surface 55. On the other hand, the stator core 21 cannot be deformed into a shape approaching a quadrilateral shape simply by contracting the vicinity of the melting portion 51 with a force in a parallel direction to deform the stator core 21. Therefore, the stator core 21 can be deformed into a shape approaching a square shape by melting and deforming all the central portions of the four outer peripheral surfaces 55 of the frame 5 in the axial direction.

FIG. 4 is a cross-sectional view showing a permanent magnet type rotating electrical machine 101 (hereinafter referred to as the rotating electrical machine 101) in the case where the melting portions 51 are provided on all four outer peripheral surfaces 55 of the frame 5.
The shape indicated by the dotted line in FIG. 4 indicates the shape of the outer peripheral surface of the stator core 21 after deformation (a shape that is such a shape if the stator core 21 is not present inside). As described above, when the melting part 51 is provided at the center of each of the four outer peripheral surfaces 55, the middle part of the adjacent melting parts 51 of the frame 5 has the largest amount of deformation, and the part of the stator core 21 has an inner The pressing force P heading toward the center acts most strongly, and the stator core 21 is deformed into a shape approaching a quadrangle.

  As described above, the amount of deformation of the stator core 21 can be adjusted by adjusting the amount of heat input from the welder 11, so that the cogging torque generated from the rotating electrical machines 100 and 101 for each predetermined amount of heat input. Is monitored by a measuring instrument, and the amount of deformation of the stator core 21 that generates a desired cogging torque and the amount of heat input required therefor can be obtained. Note that the outer peripheral shape of the frame 5 is not limited to a quadrangle, and four melting portions 51 may be provided at equal intervals in a circular shape.

FIG. 5A is a waveform diagram showing a 20th-order component generated by the rotating electrical machine 100 before and after the deformation of the frame 5 and the stator core 21.
Actually, in this embodiment, since the frame 5 is deformed and the stator core 21 is fixed, the waveform diagram of “before deformation” is a method that does not involve deformation of the frame 5, for example, adhesion It is a wave form diagram of a 20th-order component in the case where it is assumed that the frame 5 and the stator core 21 are fixed by a method of fixing with an agent. In FIG. 5A, the vertical axis represents the amplitude of the twentieth component, and the horizontal axis represents the rotational position of the rotor. The dotted line indicates the 20th-order component before the deformation, and the solid line indicates the 20th-order component after the deformation.

FIG. 5B is a waveform diagram showing the sum of cogging torque generated by the rotating electrical machine 100 before and after the deformation of the frame 5 and the stator core 21. “Before deformation” is as described above.
In FIG. 5B, the vertical axis represents the amplitude of the total cogging torque, and the horizontal axis represents the rotational position of the rotor. The dotted line shows the sum of cogging torque before deformation, and the solid line shows the sum of cogging torque after deformation. It can be seen that the amplitude of the 20th-order component in FIG. 5A decreases due to the deformation of the stator core 21, and as a result, the total amplitude of the cogging torque in FIG. 5B decreases.

  According to the method for manufacturing permanent magnet type rotary electric machines 100 and 101 and permanent magnet type rotary electric machines 100 and 101 according to Embodiment 1 of the present invention, the stator core follows the contraction of frame 5 after melting of melting part 51. By deforming 21, the cogging torque of the rotating electrical machines 100 and 101 can be reduced by deliberately generating a magnetic characteristic that counteracts the magnetic characteristic that generates torque pulsation due to the cogging torque that the stator core 21 originally had. Torque pulsation can be suppressed. Moreover, since the time required for heating and cooling can be reduced as compared with the case where the entire frame is heated and cooled, the productivity of the product can be improved. In addition, since an inexpensive TIG welding machine or the like can be used to melt the melting part 51 of the frame 5, capital investment can be suppressed compared to a heating furnace such as a high-frequency heating device.

Embodiment 2. FIG.
Hereinafter, the second embodiment of the present invention will be described with reference to the drawings, focusing on the differences from the first embodiment. The first embodiment is different from the present embodiment in the shape of the melting portion of the frame, and the other configurations are the same as those in the first embodiment.
FIG. 6 is a cross-sectional view of a permanent magnet type rotating electric machine 200 (hereinafter referred to as the rotating electric machine 200) before fixing the frame 205 and the stator core 21, cut perpendicularly to the axial direction of the shaft 3. An arc-shaped groove 254 whose cross section perpendicular to the longitudinal direction is recessed toward the inside of the frame 205 is provided on the outer peripheral surface portion of the frame 205 where the melting portion 251 is provided. The amount of shrinkage of the frame 205 when the melting part 251 is melted is inversely proportional to the thickness of the member of the melting part 251. In order to increase the amount of contraction of the frame 205 by providing a groove 254 in advance in the part where the melting part 251 is provided and reducing the thickness of the part, or to obtain the same amount of contraction as in the first embodiment The required heat input can be reduced. Further, the arc-shaped groove 254 gradually increases in thickness from the bottom to the edge of the groove, and there are few sharp portions on the mold for manufacturing the iron core piece. Therefore, it contributes to the extension of the tool life.

  According to the permanent magnet type rotating electrical machine 200 and the method for manufacturing the permanent magnet type rotating electrical machine 200 according to Embodiment 2 of the present invention, when the stator core 21 is deformed so as to approach a square shape in order to reduce the cogging torque. By reducing the amount of heat input required for the welding, the electricity cost of the welding machine 11 can be reduced. Moreover, the weight reduction of the permanent magnet type rotary electric machine 200 and the material cost of the frame 205 can be reduced.

Embodiment 3 FIG.
Hereinafter, the third embodiment of the present invention will be described with reference to the drawings, focusing on the differences from the first embodiment. The first embodiment is different from the present embodiment in the shapes of the inner peripheral surfaces of the four corners of the frame, and the other configurations are the same as those of the first embodiment.
FIG. 7 is a cross-sectional view of the permanent magnet type rotating electrical machine 300 before the frame 305 and the stator core 321 are fixed, cut perpendicularly to the axial direction of the shaft 3. The frame 305 includes concave portions 16 that extend in the axial direction of the shaft 3 at four locations (four corners in the middle of the adjacent melted portions 351) of the inner peripheral surface 56 of the frame 305. Is formed to be thin. The four corner portions of the frame 305 are not easily deformed because the thickness of the frame is much thicker than the other portions. Therefore, by thinning the four corners of the frame 305, the strength of the part is reduced, and the amount of deformation in each part is increased. Thereby, if the heat input is the same, the amount of contraction of the frame 305 can be increased. Alternatively, it is possible to reduce the amount of heat input required to obtain the same shrinkage as in the first embodiment.

  According to the permanent magnet type rotating electrical machine 300 and the method for manufacturing the permanent magnet type rotating electrical machine 300 according to Embodiment 3 of the present invention, the recess 16 is provided in the thick part of the corner of the frame 305 to reduce the strength of the part. Accordingly, the stator core 21 can be easily deformed so as to approach a square shape following the deformation of the portion. In addition, the amount of heat input required to deform the frame 305 can be reduced, and the electricity cost of the welding machine 11 can be reduced. Further, by providing the recess 16 in the frame 305, the permanent magnet type rotating electrical machine 300 can be reduced in weight.

  It should be noted that the present invention can be freely combined with each other within the scope of the invention, and each embodiment can be appropriately modified or omitted.

100, 101, 200, 300 Permanent magnet type rotating electrical machine, 1 winding, 2 stator,
21 Stator core, 21a Yoke part, 21b Magnetic pole teeth part, 3 Shaft,
4 rotor, 41 rotor core, 42 permanent magnet, 5,205,305 frame,
51,251,351 melting portion, 52 one end portion, 53 other end portion, 254 groove,
7 slot, 9, 10 gap, P pressing force, 11 welding machine, 16 recess.

Claims (7)

A cylindrical stator core wound around the magnetic pole teeth;
A cylindrical permanent magnet type rotor core having a shaft inserted therein and rotating inside the stator core;
In a permanent magnet type rotating electrical machine having a frame for housing the stator core,
The frame has an inner diameter greater than the outer diameter of the stator core;
There is no seam in the circumferential direction of the outer peripheral surface,
A permanent magnet type rotating electrical machine having a melted portion melted in a range not penetrating the frame from one end portion to the other end portion of the outer peripheral surface in the axial direction of the shaft. The permanent magnet type rotating electrical machine according to claim 1, wherein a groove is provided in advance on an outer peripheral surface portion of the frame where the melting portion is provided. The permanent magnet type rotating electrical machine according to claim 2, wherein the groove has an arcuate cross section perpendicular to the axial direction of the shaft. 4. The fuser according to claim 1, wherein the fusion part is provided at four locations equally in the circumferential direction of the frame in a cross section obtained by cutting the permanent magnet type rotary electric machine perpendicularly to the axial direction of the shaft. The permanent magnet type rotating electrical machine described in 1. The permanent magnet type rotation according to claim 4, wherein the frame has a quadrangular outer peripheral shape in a cross section perpendicular to the axial direction of the shaft, and the melting portion is provided at the center of four outer peripheral surfaces of the frame. Electric. The said frame is provided with the said some fusion | melting part, The recessed part extended in the axial direction of the said shaft is provided in the internal peripheral surface of the said frame equivalent to the intermediate | middle of the said adjacent fusion | melting part. Item 6. The permanent magnet type rotating electric machine according to any one of Item 5. A cylindrical stator core wound around the magnetic pole teeth;
A cylindrical permanent magnet type rotor core having a shaft inserted therein and rotating inside the stator core;
In the method of manufacturing a permanent magnet type rotating electrical machine having a frame that houses the stator core,
A stator core insertion step of inserting the stator core into the frame having an inner diameter larger than the outer diameter of the stator core and seamless in the circumferential direction of the outer peripheral surface;
Melting a part of the outer peripheral surface of the frame in the axial direction of the shaft from one end of the outer peripheral surface to the other end in a range not penetrating the frame;
After melting by the melting step, the inner peripheral surface of the frame and the outer peripheral surface of the stator core are fixed by contraction force in the outer peripheral direction of the frame generated in the melting portion of the frame due to thermal strain during cooling. A manufacturing method of a permanent magnet type rotating electrical machine having a fixing step.

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