JP5409273B2 - Stator for adder motor - Google Patents

Description

  The present invention relates to an iron core of an electric motor, and more particularly to vibration noise reduction of a stator for an inversion motor manufactured by stacking and integrating a plurality of punched steel sheets.

  In recent years, there has been a strong demand for improving the efficiency and reducing the cost of various electric motors from the viewpoint of energy saving. On the other hand, electric motors used in refrigerators, washing machines, air conditioners, and the like have very high needs for low vibration and low noise in addition to high efficiency and low cost. In general, a stator for an electric motor is formed by punching steel plates, laminating a predetermined number of sheets, and fixing them by caulking, welding or the like. The stator is used for inserting a tooth portion, a yoke portion and a winding coil. It is an integral structure composed of a slot portion which is a gap portion, and is finally assembled as a part of an electric motor through a winding coil assembling process.

  The stator is fixedly accommodated in a motor case having an inner diameter substantially the same as the outer diameter of the stator by bolting or shrink fitting. When the stator is incorporated into the electric motor, a winding coil is wound around the tooth portion, and a rotor in which a permanent magnet is embedded is attached inside the stator. An alternating current is passed through the winding coil, a rotating magnetic field is generated between the stator and the rotor, and the electric motor rotates. When the electric motor is operated, an electromagnetic excitation force is generated by repeatedly attracting and repelling between the permanent magnet of the rotor and the tip of the stator teeth. The electromagnetic excitation force generated along with the rotating magnetic field increases the force (radial force) that tends to cause the stator to vibrate, in particular, to deform in the radial direction. The radial force concentrates on the tip of the tooth portion, propagates through the yoke portion, and vibrates the entire motor.

  When the stator is fastened to the case mounting surface by bolting, etc., it is usually fixed to the teeth so that the magnetic flux generated in the stator is not disturbed as much as possible. The region including the outer peripheral side of the yoke located on the outer peripheral side. The more fixed parts, the more the rigidity of the motor including the stator is improved and the vibration is reduced. However, the fixed part is minimized because it narrows the region (magnetic path) through which the magnetic flux flows and impairs the efficiency of the motor. It is preferable. Therefore, the fixed locations are not usually arranged on all the teeth outer peripheral sides that receive the electromagnetic excitation force described above, but are limited to several locations. From the standpoints of manufacturing cost, weight reduction, and volume reduction, the number of fixing points is preferably minimal, and the cross-sectional area of the stator is also desirably minimal from the viewpoint of weight reduction. However, when the fixing location is limited, there is a problem that the rigidity of the portion that is not fixed is locally reduced.

  Furthermore, in an internal-rotation type motor having 6 magnetic poles, attraction and repulsion to the stator core is repeated with symmetry every 120 ° at the central angle. Therefore, as shown in FIG. 1, it rotates while maintaining the spatial mode of the electromagnetic excitation force 71 having a substantially equilateral triangular shape. Electromagnetic excitation force when the three outer peripheral points of the teeth that are not fixed are located at an equal distribution (equal pitch) around the center of the inner diameter of the stator in the circumferential direction of the yoke, that is, in a substantially equilateral triangular shape No. 71 has a problem that the vibration of the stator increases because the yoke portion is locally vibrated in the region where the rigidity of the yoke portion is locally reduced, that is, in the vicinity of three unfixed points.

  As described above, it is necessary to minimize the number of fixing points present on the outer periphery of the stator as much as possible, efficiently arrange the fixing points within the limited cross-sectional area of the stator, and reduce vibration.

  Patent Document 1 discloses a rotating electrical machine composed of a rotor (rotor) and a stator (stator), and a housing for housing the rotor and the stator, and the stator parallel to a rotating shaft of the rotating electrical machine. A rotating electrical machine is disclosed, including a bolt that penetrates in any direction and is fastened to the housing, and a nut having a shape corresponding to a shaft portion of the bolt, and the nut is provided in the space. A motor case and a stator fastened with bolts at locations are illustrated. In the illustrated fastening structure, when the number of magnetic poles is 6, it includes a mode in which three yoke portions on the outer periphery of the tooth whose rigidity is locally reduced are simultaneously vibrated, and vibration may increase. Moreover, since the protrusion is provided at the outer edge of the stator (stator) for the fastening bolt, there is a problem that the stator sectional area increases and the stator volume increases.

JP 2008-48467 A

  In view of the above-mentioned problems, the present invention efficiently arranges the fixing portion to a minimum without substantially reducing the efficiency of the motor, suppresses the vibration of the steel plate of the stator that occurs during the operation of the motor, and reduces the vibration level. It aims at providing the stator for electric motors reduced.

The gist of the present invention for solving the above problems is as follows.
(1) An internal rotation type electric motor formed by punching a steel plate into a predetermined shape and laminating a plurality of one steel plate in which teeth and yokes are integrated, and having 6 magnetic poles and 9 slots In the stator for a tooth, the teeth back portion based on any one of the nine tooth back portions based on any one of the teeth back portions which are the outer peripheral portions of the yoke at the intersection of the nine tooth portions and the yoke portion. 1st pressurized et during meter around, third, fifth, seventh rotor type electric motor stators inner only the tooth back portion, characterized in that it is fixed to the motor case.
(2) The stator for an inversion motor according to (1), wherein the teeth back portion is fixed to the case with a bolt.
(3) The stator for an internal rotation type electric motor according to (1) or (2), wherein the fixing portion of the teeth back portion is located in a range of 0.5 times or less of the yoke thickness from the outer periphery of the yoke.

  According to the present invention, it is possible to efficiently arrange a fixed portion with a minimum, without substantially reducing the efficiency of the electric motor, to suppress the vibration of the steel plate of the stator that occurs when the electric motor is operated, and to reduce the vibration level.

It is a figure which shows the spatial mode of electromagnetic excitation force. It is a figure which shows the upper surface of the stator for internal motors. It is a figure which shows the cross section of the stator for internal motors. It is a figure which shows an example of the shape of the stator for adduction type electric motors. It is a figure which shows an example of the shape of the stator for adduction type electric motors. It is a figure which shows an example of the shape of the stator for adduction type electric motors. It is a figure which shows an example of the shape of the stator for internal rotation type motors by this embodiment. It is a figure which shows the frequency characteristic of each stator. It is a figure which shows the vibration level comparison at the time of the peak frequency of each stator. It is a figure which shows the natural vibration mode of the stators A and B. FIG. It is a figure which shows the outline | summary of a magnetic flux flow. It is a figure which shows the Example of the stator for adduction type electric motors. It is a figure which shows the vibration acceleration level comparison of each stator.

  Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings.

  FIG. 2 is a top view of an inversion motor with 6 magnetic poles and 9 slots used for an air conditioner and a compressor of a refrigerator. FIG. 3 is a cross-sectional view taken along the line A-A ′ where a fastening bolt is present in the adder motor. As shown in FIG. 2, the internal motor includes a stator 11 and a rotor 12, and the stator 11 includes an annular yoke portion 13 and nine teeth portions 15 extending radially inward from an inner periphery 14 of the yoke portion. And nine slot portions 17 which are gap portions for inserting the winding coil 22. As shown in FIG. 3, the stator 11 is fastened to the mounting base 21 of the motor case by a bolt 25 penetrating the stator 11 and the mounting base 21. The stator 11 is a concentrated winding stator in which a winding coil 22 is directly wound around a tooth portion 15 before being incorporated into an adder motor.

  A rotor 12 in which six permanent magnets 23 are embedded is attached to the inside of the stator 11 so as to be rotatable about a rotation axis. An alternating current is passed through the winding coil 22, a magnetic field is generated between the stator 11 and the rotor 12, and the electric motor rotates. When the electric motor is operated, attraction and repulsion are repeated between the permanent magnet 23 of the rotor 12 and the tooth tip 16 of the stator, an electromagnetic excitation force 71 is generated, and the entire electric motor vibrates.

  The internal rotation type motor having 6 magnetic poles rotates while maintaining the spatial mode of the electromagnetic excitation force 71 having a substantially equilateral triangular shape shown in FIG. 1 as described above. On the other hand, when three points on the outer periphery of the tooth portion 15 where the bolt 25 is not present are selected, the three points on the outer periphery are located at equal intervals (equal pitch) around the center of the stator inner diameter in the circumferential direction of the yoke portion. That is, it may be located in a triangular shape. At this time, the electromagnetic exciting force 71 simultaneously vibrates a region where the rigidity of the yoke portion located on the outer peripheral side of the tooth portion is locally reduced, that is, a region where the bolt 25 is not present. It is considered that vibration increases.

From this, the present inventors analytically investigated the relationship between the vibration characteristics and the bolt arrangement of the stator for an inversion motor with 6 magnetic poles shown in FIG. 2 using the finite element method. Details of this study will be described later, in the slot number in magnetic poles are 6-pole nine stator, when a reference any one of a tooth back portion, all nine teeth back portion sac Chi 1st clockwise, third, fifth, and seventh teeth back portion to be fixed to the motor case, it has been found to be effective in reducing vibration during motor operation. In other words, the bolt arrangement in which the electromagnetic reaction force does not simultaneously act on the three locations of the teeth where the teeth back portion is not bolted is effective in reducing vibration during operation of the electric motor.

  FIG. 9 shows a stator for an inversion motor according to an embodiment of the present invention that is effective for reducing vibration during operation of the motor. The radius Rt = 30 mm of the tip of the tooth portion 15, the radius Ri = 45 mm of the inner periphery of the yoke portion, and the radius Ro = 55 mm of the end surface on the outer peripheral side 18 of the yoke portion. The width T of the tooth portion is 12 mm, the thickness Y of the yoke portion is 10 mm, the number of slots is 9, and the number of magnetic poles is 6. Further, the thickness of one of the steel plates to be laminated is 0.35 mm and the height of the lamination is 40 mm, and the stator is fixed to the mounting base of the motor case by bolting.

Bolt holes, the first 18-1,3 th 18-3,5 th 18-5,7 th 18-7 in clockwise all nine teeth back portion 18 caries Chi, stator circumferentially There are four places at uneven positions (unequal pitch) around the center of the inner diameter, and the stator 11 is fixed to the pedestal 21 with bolts 25. Each bolt 25 has an outer diameter of 3.5 mm, and the center of the bolt 25 is located on the central axis of the tooth and is located 2.5 mm from the outer periphery of the yoke.

  The details of the analytical investigation of the relationship between the vibration characteristics and the bolt arrangement will be described below with respect to the stator for an inversion motor with 6 magnetic poles.

4A to 4D show typical examples of the stator shape used for the analysis. In the stator of FIG. 4A, the bolt 25 is attached to the yoke outer peripheral portion at the intersection of the nine tooth portions 15 and the yoke portion 13, that is, three locations 18-1, 18-4, and 18-7 on the tooth back portion 18. It exists and is arranged at equal positions (equal pitches) around the center of the stator inner diameter in the circumferential direction (hereinafter referred to as “equal pitch positions in the circumferential direction”). Figure 4 stator (b) is a bolt 25, total nine teeth back first 18-1,2 th clockwise unit 18 caries Chi 18-2,4 th 18-4,7 th 18 In -7, there are four positions at unequal (unequal pitch) positions (hereinafter referred to as “equal pitch positions in the circumferential direction”) around the center of the inner diameter of the stator in the circumferential direction. Figure 4 stator (c), the bolt 25, all nine teeth back first 18-1,2 th clockwise unit 18 caries Chi 18-2,4 th 18-4,5 th 18 On the fifth and seventh 18-7, there are five positions at unequal pitches in the circumferential direction. Figure 4 stator (d) is a bolt 25, total nine teeth back first 18-1,3 th clockwise unit 18 caries Chi 18-3,5 th 18-5,7 th 18 In -7, there are four positions at unequal pitches in the circumferential direction.

  4 (a) to 4 (c), in the case of selecting the three peripheral points 18-3, 18-6, and 18-9 of the teeth where the teeth back portion 18 is not fixed by the bolt 25. Further, it includes a form in which the three outer peripheral points 18-3, 18-6, and 18-9 are arranged at equal pitch positions in the circumferential direction of the yoke portion, that is, located in a substantially equilateral triangle shape. On the other hand, FIG. 4D shows, for example, the outer peripheral portions 18-2, 18-6, 18- no matter how the three outer peripheral locations of the teeth where the teeth back portion 18 is not fixed by the bolts 25 are selected. The three outer peripheral points having no fixed portion such as 8 are not arranged at equal pitch positions in the circumferential direction of the yoke portion.

  As described above, the internal-rotation motor having 6 magnetic poles rotates while maintaining the spatial mode of the electromagnetic excitation force having a substantially equilateral triangular shape, as described above. A dynamic load 41 was applied in the three directions of the tooth tip 16 at the pitch position, and a frequency response analysis of the stator that calculates the frequency response at the response evaluation point 42 was performed. 4 (a) to 4 (c), three directions of dynamic loads are simultaneously applied to three locations on the tooth tip 16 where the teeth 25 are not locally present and the rigidity is locally reduced. If it acts, vibration will increase. Further, in the stator of FIG. 4D, the dynamic load in two directions among the dynamic loads in the three directions acts on the tooth tip portion 16 where the bolt 25 is not present in the teeth back portion 18 and the rigidity is locally reduced. However, since the dynamic load in one direction acts on the teeth back portion where the bolts 25 are present, the vibration is expected to be smaller than in FIGS. 4 (a) to 4 (c).

  FIG. 5 is a comparative example of frequency response characteristics in each stator shown in FIGS. 4A to 4D, and FIG. 6 is a comparison of vibration levels at peak frequencies in each stator. It is. The response characteristics are those at the response evaluation point 42 shown in FIG. 4, and the acceleration per unit dynamic load is evaluated as a vibration value. FIG. 7 shows the eigenmode at the peak frequency in the frequency response characteristic shown in FIG. 5 obtained by eigenmode analysis by the finite element method, and is an example of the stator of FIG. Each stator has a triangular natural vibration mode, and each peak frequency existing in the vicinity of 4000 Hz in the frequency response characteristic of FIG. 5 corresponds to the natural frequency in the triangular natural mode. In the stator shown in FIG. 4D, the vibration value at the time of peak vibration is about 3 to 4 dB smaller than that of the stator shown in FIGS. 4A to 4C, and in the region including the teeth back portion 18. Even if the bolts 25 are arranged at unequal pitches in the circumferential direction and the teeth back portion 18 has no fixing points with the bolts 25, the outer peripheral points of the three points are selected in any way. It can be seen that it is effective to reduce vibration during operation of the electric motor if it is not arranged at a position at an equal pitch in the circumferential direction of the yoke portion.

  On the other hand, when a stator having 6 magnetic poles and 9 slots is incorporated in an internal motor, an alternating current is applied to the winding coil, and the motor operates, as shown in FIG. The magnetic flux 52 of the yoke portion that connects the magnetic flux 51 that flows in the radial direction through the portion 15 tends to concentrate in the area 53 indicated by the hatched portion. The region 53 where the magnetic flux concentrates is in a range of about 0.5 times the yoke portion thickness Y in the radial direction. Therefore, in order not to deteriorate the iron loss of the electric motor, the bolt 25 is preferably present at a position where the magnetic flux flow of the magnetic fluxes 51 and 52 is not disturbed. Therefore, the bolt 25 is preferably provided in the yoke outer peripheral region (tooth back portion 18) at the intersection of the tooth portion 15 and the yoke portion 13, and is located in a range of 0.5 times or less the yoke thickness from the yoke outer periphery. preferable.

From the above, the number of slots in the magnetic poles are 6-pole nine stator, any one of a tooth back portion when a reference, the clockwise all nine teeth back portion sac Chi Fixing the first, third, fifth, and seventh teeth back portions to the case of the motor is effective in reducing vibration during operation of the motor. In other words, the bolt arrangement in which the electromagnetic reaction force does not act simultaneously on the three locations of the teeth where the bolts are not fastened to the teeth back portion is effective in reducing vibration during operation of the motor.

  A confirmation test was performed on each of the stators shown in FIGS. 4 (a) to 4 (d). In this test, an electric motor equipped with each stator was operated under the conditions of a rotational speed of 2000 [rpm] and a torque of 4 [Nm], an accelerometer was attached to the outer periphery of the case, and the vibration acceleration of the case was measured. The vibration acceleration level was measured up to a frequency range up to 10 kHz, and evaluated with an overall value [dB].

  FIG. 10 is a diagram showing an overall value [dB] in each stator shown in FIGS. 4 (a) to 4 (d). The horizontal axes (a) to (d) show the stator shown in FIGS. 4 (a) to 4 (d). It was confirmed that the vibration acceleration level (d) of the electric motor equipped with the stator according to the embodiment shown in FIG. 9 was lower than the other vibration acceleration levels (a) to (c).

  Moreover, each bolt is located on the outer peripheral side of the yoke part located on the outer peripheral side of the tooth part that does not disturb the magnetic flux, and hardly reduces the efficiency of the electric motor.

DESCRIPTION OF SYMBOLS 11 Stator 12 Rotor 13 York part 14 York part inner periphery 15 Teeth part 16 Teeth tip part 17 Slot part 18, 18-1 to 18-9 Teeth back part 21 Base 22 Winding coil 23 Permanent magnet 24 Bolt hole 25 Bolt 41 Dynamic load 42 Response evaluation point 51 Magnetic flux flowing in the radial direction 52 Magnetic flux in the yoke portion 53 Area where the magnetic flux concentrates 71 Electromagnetic excitation force

Claims (3)

A stator for an internal motor, which is formed by punching a steel plate into a predetermined shape and laminating a plurality of one steel plate in which a tooth portion and a yoke portion are integrated, and having 6 magnetic poles and 9 slots. in, when nine basis any one of a tooth back portion is a yoke outer periphery part of the cross section of the tooth portion and the yoke portion, all nine teeth back portion or Once you have the reference of the tooth back portion Only the first, third, fifth, and seventh teeth back portions are fixed to the case of the motor around the meter.   The stator for an inversion motor according to claim 1, wherein the teeth back portion is fixed to the case with bolts.   3. The stator for an internal rotation type electric motor according to claim 1, wherein the fixing portion of the teeth back portion is located in a range of 0.5 times or less of the yoke thickness from the outer periphery of the yoke.

Images