JPH059147U - Electric motor rotor - Google Patents

Abstract

(57) [Summary] [Object] An object of the present invention is to provide a rotor of an electric motor capable of reducing torque ripple due to armature reaction without increasing the size of the electric motor. [Structure] The magnetic pole member 21 is provided with a plurality of voids C2 so as to divide a magnetic path in the magnetic pole member 21.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

  The present invention is rotatably placed inside the stator through a flange and a bearing. Rotor structure of a permanent magnet type electric motor having a fixed rotor.

[0002]

[Prior art]

  FIG. 3 shows an example of a rotor and a stator of a conventional 6-pole electric motor viewed from the axial direction. It is a diagram, and windings and magnetic paths are described only for a pair of N pole and S pole. The other parts are omitted because they are equivalent. The rotor 10 is punched or the like. A magnetic pole member 11 made by laminating a plurality of steel plates made of a magnetic material is pressed into the shaft 1 and fired. The magnetic pole member 11 is fixed by baffle or adhesive so that the outer circumference of the magnetic pole member 11 becomes different poles. The block-shaped magnet 12 is disposed so as to move. Here, the outer peripheral portion of the magnetic pole member 11 Is a cross-sectional area where adjacent different poles are saturated with minute magnetic flux that is practically acceptable. It has been succeeded by. Further, the same pole (S pole in the figure) is provided on the inner circumference of the magnetic pole member 11 as the shaft 1 The entire circumference has an area that does not cause stress fracture even if it is fitted to the other pole ( (N pole in the figure) is magnetically insulated by a gap C1 provided in the radial direction. As a reinforcement against centrifugal force, leakage magnetic flux is not a practical problem for the motor. The magnetic pole member 11 and the inner peripheral portion of the magnetic pole member 11 are joined to each other with a minimum necessary cross-sectional area within a range that does not occur. It may be turned off.

[0003]   A stator 13 is provided on the outside of the rotor 10 configured as described above, and The stator 13 is a stator formed by laminating a plurality of steel plates made of a magnetic material made by punching or the like. Three-phase winding wound around the core 14 and the slot 15 provided in the stator core 14. 16 and 16. Considering the magnetic path of this motor, the stator core 14 and the magnetic The air gap C1 in the magnetic pole member 11 is much larger than the air gap with the outer periphery of the pole member 11. Since the magnetic resistance is large, the magnetic flux passes through the N pole magnetic pole member 11 and From the outer periphery of 11 to the adjacent S pole through the teeth and yoke of the stator core 14. (Dotted line arrow). Now, let us consider the principle of torque generation of this electric motor. Assuming that the rotational angle position of the rotor 10 is θ, it is directly connected to the winding 16 of each of the three phases (U, V, W). When the effective magnetic flux densities Bu, Bv, and Bw that intersect are the maximum effective magnetic flux density Bo, The electric motors are designed so that the numbers are 1, 2, and 3, respectively.

[0004]

[Equation 1]     Bu = Bo · cos θ

[Equation 2]     Bv = Bo · cos (θ + (2/3) π)

[Equation 3]     Bw = Bo · cos (θ + (4/3) π) Further, the currents Iu, Iv, and Iw flowing through the respective phases of the winding 16 are set to the maximum value Io. It is controlled so as to be the number 4, the number 5, and the number 6, respectively.

[Equation 4]     Iu = Io · cos θ

[Equation 5]     Iv = Io · cos (θ + (2/3) π)

[Equation 6]     Iw = Io · cos (θ + (4/3) π) At this time, the torque T generated by the electric motor is as shown in Equation 7, and the rotational angular position of the rotor 10 is It can be seen that it is constant regardless of the position θ and is proportional to the current Io.

[0005]

[Equation 7]     T = Bu · Iu + Bv · Iv + Bw · Iw       = Bo ・ cos θ ・ Io ・ cos θ         + Bo ・ cos (θ + (2/3) π) ・ Io ・ cos (θ + (2/3)         π)         + Bo ・ cos (θ + (4/3) π) ・ Io ・ cos (θ + (4/3)         π)       = (3/2) Bo · Io   The current I flowing in each phase and the winding of each phase at the rotation angle position θ of the rotor 10 The relationship of the magnetic flux density B orthogonal to 16 is as shown in FIGS. 4 (A) and 4 (B).

[0006]

[Problems to be solved by the device]

  Consider the state when the current is actually applied to the winding 16 in the conventional electric motor described above. Then, a magnetic circuit as shown by a solid arrow in FIG. 3 called an armature reaction is formed. It At this time, the magnetic flux density in the magnetic pole member 11 is relative to the saturation magnetic flux density of the magnetic pole member 11. Usually, there is enough margin and the magnetic flux is free to move. The magnetic flux in the magnetic pole member 11 shown by the dotted arrow in the figure is easily distorted by the magnetic flux. I will be lost. Therefore, the magnetic flux density orthogonal to each phase of the winding 16 should have a cosine wave shape. However, the phase is out of phase, resulting in a torque ripple in the output torque of the motor. A phenomenon occurs in which the torque largely pulsates depending on the rotation angle position of the rotor.

[0007]   As a method of reducing the torque ripple, the outer circumference of the magnetic pole member 11 and the stator 1 By increasing the air gap in the inner circumference of 3, the magnetic circuit by the armature reaction On the other hand, it is possible to increase the magnetic resistance to reduce the effect. As a result, the effective magnetic flux density decreases and the motor efficiency decreases, resulting in a large motor. There was a problem of becoming.   The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to expand the electric motor. It is possible to reduce the torque ripple due to the armature reaction without shaping the motor. To provide data.

[0008]

[Means for Solving the Problems]

  According to the present invention, a magnetic pole member made of a magnetic material and the magnetic pole member are arranged in the circumferential direction in order. Next, a motor rotor having block-shaped permanent magnets arranged to have different poles The above object of the present invention is to divide the magnetic path in the magnetic pole member. This is accomplished by providing the magnetic pole member with a plurality of voids.

[0009]

[Action]   In the present invention, due to the armature reaction due to the plurality of gaps provided in the magnetic pole member The magnetic resistance is increased relative to the magnetic circuit, and the magnetic flux is distorted by the armature reaction. Since the torque is reduced, the torque ripple of the electric motor can be reduced.

[0010]

【Example】

  FIG. 1 is an axial view of an example of a rotor of a motor according to the present invention. Only the portion is described, and other magnetic pole portions are omitted because they have the same configuration. . In addition, the same components as those in FIG. Magnet of the rotor 20 The pole member 21 includes a magnet 12 and a stator arranged outside the rotor 20 (not shown). A plurality of voids C2 are provided along the magnetic path that connects to the magnetic pole member 21. Penetrates in the longitudinal direction. Due to the plurality of voids C2, the magnetism in the magnetic pole member 21 is reduced. The road is divided into a plurality of parts. The width dimension of the air gap C2 depends on the magnetic path divided by the air gap C2. The total cross-sectional area reaches the limit of magnetic saturation due to the total magnetic flux from the magnet 12. Is decided.   In the rotor 20 configured in this way, an armature current was passed through the winding 16. The air gap C2 has a large magnetic resistance with respect to the magnetic circuit due to the armature reaction that sometimes occurs. And the force to distort the magnetic flux in the magnetic pole member 21 due to the armature reaction is large. Is reduced to. Also, at this time, although some influence due to armature reaction remains, The magnetic path in the magnetic pole member 21 is divided by the air gap C2, and the sectional area of each divided magnetic path is Since the magnetic flux is saturated by a slight increase in the magnetic flux, The magnetic flux distribution is hard to change. Therefore, the torque ripple due to the armature reaction is greatly reduced. It can be reduced.

[0011]   FIG. 2 is a view showing another example of the rotor of the electric motor of the present invention in correspondence with FIG. A plurality of voids C3 are provided in a substantially outer circumferential direction of the magnetic pole member 31, and the voids C3 are It penetrates in the longitudinal direction of the magnetic pole member 31. The magnetic pole portion is formed by the plurality of voids C3. The magnetic path in the material 31 is divided. The width dimension of the void C3 is divided by the void C3. The total cross-sectional area of the magnetic path is about the limit of magnetic saturation due to the total amount of magnetic flux from the magnet 12. Has been decided to be.   In the rotor 30 configured as described above, the gap C3 has been described with reference to FIG. Similarly to, it has a large magnetic resistance against the magnetomotive force due to the armature reaction. Also empty The magnetic path is divided by the gap C3, and the sectional area of each of the divided magnetic paths causes a slight increase in magnetic flux. Since it is made to be more magnetically saturated, the magnetic flux distribution on the outer circumference of the magnetic pole member 31 does not change. Peg. Therefore, torque ripple due to armature reaction can be significantly reduced. . Here, the shape of the void C2 is described as a square, but the purpose of dividing the magnetic path is achieved. It should be possible, for example, a circle.

[0012]   It should be noted that the air gap may be created by punching at the same time when punching the magnetic pole member. it can. Further, although the above-described embodiment has been described with respect to a 6-pole electric motor, It is not limited to this, and any pole may be used as long as it is physically permissible. Change Applied to a rotor with a structure in which the divided magnetic pole members and magnets are alternately arranged. It is possible.

[0013]

[Effect of device]

  As described above, according to the electric motor rotor of the present invention, the torque can be increased without increasing the size of the electric motor. Since the ripple can be reduced, a high-precision motor can be It is possible to suppress the vibration and abnormal noise of the machine used.

[Brief description of drawings]

FIG. 1 is an axial view of an example of a rotor of an electric motor according to the present invention.

FIG. 2 is a view of another example of the rotor of the electric motor of the present invention as seen from the axial direction.

FIG. 3 is a view of an example of a rotor and a stator of a conventional electric motor as viewed from the axial direction.

FIG. 4 is a diagram showing a relationship between a current flowing through a three-phase winding and a magnetic flux density orthogonal to the three-phase winding with respect to a rotor rotation angle position.

[Explanation of symbols]

10, 20, 30 rotor 11, 21, 31 Magnetic pole members C1, C2, C3 void

Claims (3)

[Scope of utility model registration request] 1. A rotor of an electric motor, comprising: a magnetic pole member made of a magnetic material; and a block-shaped permanent magnet arranged so that the magnetic pole member sequentially has different poles in a circumferential direction. A rotor for an electric motor, characterized in that a plurality of gaps are provided in the magnetic pole member so as to divide a magnetic path. 2. The rotor of an electric motor according to claim 1, wherein the gap is provided along a magnetic path in the magnetic pole member. 3. The rotor for an electric motor according to claim 1, wherein the gap is provided in a circumferential direction of a substantially outer circumference of the magnetic pole member.