JP5361276B2 - Rotating electric machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To eliminate vibration and noise caused by eccentricity of a rotor. <P>SOLUTION: In a rotary electric machine, a stator and a rotor are eccentric and opposing windings of the stator are wound different number of turns so as to balance a magnetic flux induced from the opposing windings of the stator. Under a state where the centers of the stator and rotor coincide with each other, the length of a space between the tip of tooth on the stator side and the rotor is made &le;1/2 as large as the distance between the yoke of the stator and the rotor. A terminal for measuring a voltage induced in the windings is provided. The magnetic flux is balanced, thereby the rotary electric machine with low vibration and low noise can be manufactured at a low cost. Moreover, the magnetic flux can be balanced just by adjusting the number of turns a little. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a rotating electrical machine, and more particularly, to a rotating electrical machine that is required to reduce vibration and noise, for example, used for driving a fan of home appliances.

  In conventional rotating electrical machines that require low vibration and low noise, vibration transmission generated during rotation is reduced by using anti-vibration materials or by precisely aligning the rotor rotation axis and stator center axis. Or reducing the excitation force. However, in such a rotating electrical machine, an increase in cost due to the vibration-proof material and an increase in cost due to high-precision processing are inevitable. Further, recent rotary electric machines are required to be small and highly efficient, and the gap length between the rotor and the stator is very small. Even when the rotation axis of the rotor and the center axis of the stator are matched with high accuracy, it is virtually impossible to achieve a state in which there is no axial deviation.

  Therefore, in order to realize effective vibration reduction and noise reduction, it is based on winding unbalance data generated uniformly by the winding method and measurement data on unbalance of individual armature cores. Thus, a method has been proposed in which the number of turns of the winding is determined so as to eliminate the unbalance of the armature after the winding is applied, and the balance is simultaneously corrected in a normal winding processing step. As a result, no special work process or dedicated processing equipment is required, and the efficiency of the motor can be prevented from being lowered because it is not configured to delete a part of the armature or attach a correction material (for example, Patent Document 1).

JP-A-8-98477

  In such a rotating electric machine, a low-vibration and low-noise rotating electric machine can be realized at low cost, but the winding and the teeth that wind the winding are in a relatively narrow space between the stator yoke and the rotor. The number of windings that can be adjusted is limited, and it may be difficult to reduce vibration and noise by adjusting the number of windings.

  Therefore, an object of the present invention is to reduce the number of windings within a practical adjustment range of the number of windings when reducing vibration and noise by using means for changing the number of windings. The adjustment is to balance the magnetic flux to obtain a rotating machine with low vibration and low noise.

  In the rotating electrical machine according to the present invention, the opposing windings of the stator are arranged such that the center of the stator and the center of the rotor are eccentric and the magnetic flux induced from the opposing windings of the stator is balanced. In a rotating electrical machine having different numbers of windings, the gap length between the stator tooth tip and the rotor when the center of the stator and the center of the rotor coincide with each other is The distance between the rotor and the rotor is ½ or less of the distance between the rotor and the rotor.

  According to the present invention, it is possible to obtain a rotating machine with low vibration and low noise by balancing the magnetic flux by adjusting a relatively small number of windings within a practical adjustment range of the number of windings.

Embodiment 1 FIG.
FIG. 1 shows a rotary electric machine according to Embodiment 1 of the present invention in a cross-sectional view perpendicular to the axis. In FIG. 2, the rotating electrical machine includes a hollow cylindrical stator 1 and a rotor 2 that can rotate within the stator 1. The stator 1 includes a core 3 and windings 4a to 4d. The core 3 is separated from a hollow cylindrical yoke 7 having an outer peripheral surface 5 and an inner peripheral surface 6 by 90 ° in the circumferential direction of the yoke 7. And four teeth 8 a to 8 d extending from the inner peripheral surface 6 toward the rotor 2. The windings 4a to 4d are wound around the teeth 8a to 8d, respectively.

  In the rotating electrical machine of FIG. 1, the center 10 of the rotor 2 is slightly eccentric with respect to the center 9 of the stator 1 only in the direction from the teeth 8a to the teeth 8c (leftward in FIG. 1). The main magnetic flux induced from the pair of windings 4a and 4c facing each other is as shown as magnetic fluxes Fa to Ff, and these magnetic fluxes Fa to Ff are balanced. In the case of the rotating electrical machine of FIG. 1, since the rotor 2 is eccentric as described above, the opposing windings 4a and 4c have different numbers of windings, but the opposing windings 4b and 4d are different from each other. Since there is no eccentricity in the facing direction, the number of windings is the same.

  Further, the gap ga between the tips of the teeth 8a to 8d of the stator 1 and the cylindrical outer peripheral surface 12 of the rotor 2 in a state where the center 9 of the stator 1 and the center 10 of the rotor 2 coincide with each other. The size of ˜gd, that is, the gap length g is ½ or less of the distance h between the inner peripheral surface 6 of the yoke 7 that is the outer ring portion of the stator 1 and the outer peripheral surface 12 of the rotor 2, that is, g ≦ h / 2.

  In the rotating electrical machine shown in FIG. 1, since the center 10 of the rotor 2 is slightly eccentric with respect to the center 9 of the stator 1, the four gap lengths g between the rotor 2 and the four teeth 8a to 8d. Differs depending on the magnitude (eccentricity) and direction (eccentric direction) of the eccentricity. For this reason, the magnetic resistance of the magnetic path of the magnetic flux generated by the windings 4a to 4d is also different depending on the eccentricity and the eccentricity direction. Thus, an imbalance occurs in the amount of magnetic flux that enters the rotor 2 through the gaps ga to gd. However, in FIG. 1, for example, if the rotor 2 is eccentric only in the right direction with respect to the stator 1, the gap ga is smaller than the gap gc, which is due to the unbalance of the magnetic resistance of the magnetic path passing therethrough. The magnetic flux unbalance occurs, but is eliminated by making the number of turns of the windings 4a facing each other larger than the number of turns of the winding 4c so that the induced magnetic fluxes Fa to Ff are balanced. As shown in FIG. 1, the magnetic fluxes Fa to Ff that come out of the windings 4a and 4c facing each other and enter the rotor 2 through the gaps ga and gc are in an equilibrium state.

  FIG. 1 shows a rotating electric machine having four teeth, and windings 4a to 4d are wound around the teeth 8a to 8d, respectively. The core 3 of the stator 1 is usually made of a magnetic material such as iron, and FIG. 1 shows a concentrated winding method in which the windings 4a to 4d are wound around the teeth 8a to 8d, respectively. The number of turns of the windings 4a to 4d may be adjusted by changing the number of turns for one set or two sets of mutually opposing windings depending on the amount of eccentricity and the direction of eccentricity. Therefore, for example, when the rotor 2 is eccentric only to the right in FIG. 1 with respect to the stator 1, the number of turns of the winding 4a is made smaller than the number of turns of the winding 4c or the winding 4c The number of turns may be made larger than the number of turns of the winding 4a. When the eccentric direction has an upward or downward component in FIG. 1, it is necessary to make the number of turns different for the pair of windings 4b and 4c.

  A rotor 2 is installed inside the stator 1. Magnetic fluxes Fa to Ff are generated when current flows through the windings 4a to 4d. FIG. 1 shows a case where current flows through the windings 4a and 4c. The main magnetic fluxes at this time are magnetic fluxes Fa to Ff generated by the windings 4a and 4c, and the magnetic fluxes Fa and Fb are teeth. 8a, through the gap ga between the teeth 8a and the rotor 2, through the rotor 2, through the gap gc between the rotor 2 and the teeth 8c, through the teeth 8c, and between the teeth 8c and the core 3 The magnetic flux Fa branches into two magnetic fluxes Fa and Fb at the joint with the yoke 7, and the magnetic flux Fa flows through the upper semicircular portion of the yoke 7 over a half circumference and returns to the teeth 8 a. And then returns to the tooth 8a, and the magnetic fluxes Fa and Fb join again at the tooth 8a.

  Further, the magnetic flux in the teeth 8a flows into the rotor 2 through the gap ga, enters the teeth 8b through the gap gb between the teeth 8b, and enters the yoke 7 by a quarter circumference. The magnetic flux Fc that flows in the clockwise direction and enters the teeth 8a again, and enters the teeth 8d from the rotor 2 through the gap gd and flows through the yoke 7 in the counterclockwise direction in FIG. And a magnetic flux Fd that enters.

  Further, the magnetic flux in the teeth 8c flows through the yoke 7 in the clockwise direction in FIG. 1 by a quarter circumference, enters the teeth 8b, flows into the rotor 2 through the gap gb, and then passes through the gap gc. The magnetic flux Fe that again enters the teeth 8c and the yoke 7 flows counterclockwise in FIG. 1 by a quarter circumference, enters the teeth 8d, flows into the rotor 2 through the gap gd, and then passes through the gap gc. Thus, a magnetic flux Ff entering the teeth 8c again is formed. Further, although not shown in the drawing, there is a magnetic flux that leaks directly from the rotor 2 to the yoke 7 that is the outer ring portion of the core 3.

  In the case of an ideal rotating electrical machine, the center 9 of the stator 1 and the center 10 of the rotor 2 are completely coincident with each other, the number of windings of the opposing windings 4a and 4c is equal, and the opposing windings are the same. The number of windings of lines 4b and 4d is equal. Here, a two-pole capacitor motor in which the windings 4a and 4c are main windings and the windings 4b and 4d are auxiliary windings will be described. When current flows through the windings 4a and 4c, main magnetic fluxes Fa to Ff are distributed as shown in FIG. 1, but in an ideal rotating electrical machine, the center 9 of the stator 1 and the center 10 of the rotor 2 are completely Therefore, the magnetic fluxes Fa and Fb are equal, and the magnetic fluxes Fc, Fd, Fe, and Ff are equal. Accordingly, since the magnetic flux distribution is symmetric with respect to the centers 9 and 10, no radial force is generated.

  Thus, in an ideal rotating electrical machine in which the center 9 of the stator 1 and the center 10 of the rotor 2 completely coincide, the number of windings of the windings 4a and 4c is equal, and the windings 4b and 4d When the number of windings is equal, it is considered that no radial excitation force is generated with respect to the rotating shaft, and therefore vibration and noise are hardly generated.

  In an actual rotating electrical machine, when the number of windings 4a and 4c is equal, the number of windings 4b and 4d is equal, and the center 9 of the stator 1 and the center 10 of the rotor 2 are shifted. Since vibration and noise are generated, many studies have been made to make the center 9 of the stator 1 coincide with the center 10 of the rotor 2. However, in an actual rotating electrical machine, it is difficult to make the center 9 of the stator 1 and the center 10 of the rotor 2 completely coincide with each other. The center 10 is in a shifted state. That is, in an actual rotating electric machine, in most cases, the center of the stator 1 and the center of the rotor 2 are in an eccentric state.

  In the rotating electrical machine of FIG. 1, the number of windings 4a and 4c is equal, the number of windings 4b and 4d is equal, and the center 10 of the rotor 2 is on the left side of the page with respect to the center 9 of the stator 1. Consider the case of eccentricity. At this time, the gap length of the gap ga between the teeth 8a and the rotor 2 is larger than that when there is no eccentricity. Therefore, the magnetic resistance of the gap ga is larger than when there is no eccentricity. On the other hand, since the gap length of the gap gc between the teeth 8c and the rotor 2 is smaller than that when there is no eccentricity, the magnetic resistance of the gap gc is smaller than when there is no eccentricity. Further, the gap length of the gap gb between the teeth 8b and the rotor 2 or the gap length of the gap gd between the teeth 8d and the rotor 2 is assumed to be substantially the same as when there is no eccentricity. Since the strength (magnitude) of the magnetic flux is inversely proportional to the magnetic resistance, the magnetic fluxes Fc and Fd are weak (small) and the magnetic fluxes Fe and Ff are strong (large). Further, it is considered that the strengths of the magnetic fluxes Fa and Fb do not change so much because both the gap ga where the magnetic resistance increases and the gap gc where the magnetic resistance decreases are included. Actually, there are magnetic fluxes other than the magnetic fluxes Fa, Fb, Fc, Fd, Fe, and Ff shown in FIG. 1, and it is necessary to consider them.

  From the above, when the center 10 of the rotor 2 is eccentric to the left side of the page with respect to the center 9 of the stator 1, the magnetic flux passing through the gap ga between the teeth 8a and the rotor 2 becomes weak and rotates with the teeth 8c. The magnetic flux passing through the gap gc between the children 2 becomes stronger. Therefore, the magnetic flux distribution becomes asymmetric. Since the electromagnetic force is proportional to the square of the strength of the magnetic flux, in this case, the electromagnetic force in the left direction on the paper acts on the rotor 2. Since this electromagnetic force fluctuates during motor rotation, a radial excitation force is generated, causing vibration and noise. In the present invention, for an actual rotating electrical machine that is in an eccentric state to some extent, the radial excitation force is reduced by adjusting the number of turns of the winding according to the eccentric state.・ To reduce noise.

  There are many means for adjusting the number of windings. A method of determining the number of turns corresponding to the mass production line so that the magnetic flux is balanced can be considered by referring to the result of measuring the dimensions of the rotating electrical machines manufactured on the same mass production line with high accuracy. Further, a method of measuring the magnetic flux induced from each winding during the assembly of the rotating electrical machine and adjusting the magnetic flux to be balanced while changing the number of turns can be considered. Another possible method is to assemble a rotating electrical machine, measure the magnetic flux induced from each winding, and add a winding for adjustment to balance the magnetic flux. For the magnetic flux induced from each winding, a method for measuring the magnetic flux passing through the teeth in which each winding is wound, a method for measuring the magnetic flux in the gap portion between the teeth and the rotor in which each winding is wound, There is a method of measuring the inductance of a wire. Also, regarding the relationship between the amount of magnetic flux induced from each winding and the number of turns to be adjusted, grasp the relationship between the method of adjusting the number of turns while measuring the magnetic flux, etc., and the relationship between the measurement result of magnetic flux and the number of turns to be adjusted. A method of adjusting the number of windings and a method of adjusting the number of windings by grasping in advance the relationship between the dimension measurement result and the number of windings to be adjusted are conceivable.

  In the present embodiment, the case of the concentrated winding method in which there are four teeth and the winding is wound around each tooth has been described, but the same is basically applied to the case where the number of teeth is large or distributed winding. . Further, although a two-pole capacitor motor in which the winding is composed of a main winding and an auxiliary winding has been described, the same applies to a multi-phase rotating electric machine, and the same applies to a rotating electric machine having a large number of poles. The same applies to a rotating electrical machine including a permanent magnet. According to the present invention, it is described that there is a vibration / noise reduction effect because the radial excitation force can be reduced. However, since the magnetic flux distribution is balanced, there is also an effect of reducing the excitation force in the rotational direction, and the axial direction. It is considered that there is also an effect of reducing the excitation force. In addition, it is possible to control the radial force by configuring the windings wound around the teeth with independent circuits and controlling the current of each winding. As a result, it is possible to reduce the radial excitation force. However, this increases the cost because the circuit becomes complicated. On the other hand, in the present invention, since the number of windings is changed, the excitation force of the rotating electrical machine can be reduced at low cost, and a rotating electrical machine with low vibration and noise can be realized.

  Next, the dimensions of the teeth portion in the rotating electrical machine of the present invention will be described. In a state where the center 9 of the stator 1 and the center 10 of the rotor 2 coincide with each other, the distance (radius) from the center 9 to the outer peripheral surface 12 of the rotor 2 is defined as ri, and the inside of the teeth 8a to 8d of the stator 1 ( The distance to the tip) is ro, and the distance (radius) to the inner peripheral surface 6 of the yoke 7 of the stator 1 is rb. At this time, if the gap length of the gaps ga to gd between the rotor 2 and the teeth 8a to 8d is g, g = ro-ri. Further, when the distance between the outer peripheral surface 12 of the rotor 2 and the inner peripheral surface 6 of the yoke 7 of the stator 1 is h, h = rb−ri.

  FIG. 2 shows the eccentricity e with respect to the stator 1 (e <g because the rotor 2 must not contact the teeth 8a to 8d of the stator 1), and each winding 4a to 4d. The main magnetic fluxes Fa, Fb, Fc, Fd, Fg, Fh, Fi, Fj that are induced by the winding 4a when energized are shown in a rotating electrical machine having the same number of turns. Magnetic fluxes Fa to Fd are magnetic fluxes passing through the same magnetic path as that shown in FIG. The magnetic fluxes Fg and Fh pass through the gap ga between the tooth 8a around which the winding 4a is wound and the rotor 2, branch there, and pass through two magnetic paths that exit the rotor 2 and return to the yoke 7 of the stator 1. Magnetic flux. The magnetic fluxes Fi and Fj pass through the gap ga between the teeth 8a and the rotor 2, pass from the rotor 2 through the gap between the rotor 2 and the teeth 8b, branch there, exit the rotor 2, and exit from the stator. Two magnetic fluxes returning to one yoke 7.

  In order to compare the magnetic resistances of the magnetic paths through which the magnetic fluxes Fa to Fd and Fg to Fj pass, the gap lengths of the gaps ga to gd are briefly examined. Regarding the magnetic paths of the magnetic fluxes Fg and Fh, the size of the gap ga between the teeth 8a and the rotor 2 is g + e (g is the size of the gaps ga to gd when the stator 1 and the rotor 2 are not eccentric, that is, The length of the gap portion between the rotor 2 and the inner peripheral surface 6 of the portion opposite to the eccentric direction of the yoke 7 of the stator 1 is simply expressed as h + e (h is no eccentricity). The distance between the rotor 2 and the inner peripheral surface 6 of the yoke 7) is expressed as g + h + 2e in both the total gap in the magnetic path through which the magnetic flux Fg passes and the total gap in the magnetic path through which the magnetic flux Fh passes. . Regarding the magnetic paths of the magnetic fluxes Fc and Fd, the length of the gap ga between the teeth 8a and the rotor 2 is g + e, and the length of the gap gb or gd between the rotor 2 and the teeth 8b or 8d is g. Therefore, the sum of the gaps in these magnetic paths is 2 g + e. Regarding the magnetic paths of the magnetic fluxes Fi and Fj, the length of the gap ga between the teeth 8a and the rotor 2 is g + e, and the rotor 2 and the inner peripheral surface 6 of the stator 1 on the side in the eccentric direction of the yoke 7 are arranged. When the length of the gap portion between them is expressed as he, the total of the gaps in these magnetic paths is g + h. Regarding the magnetic paths of the magnetic fluxes Fa and Fb, the length of the gap ga between the teeth 8a and the rotor 2 is g + e, and the length of the gap gc between the rotor 2 and the teeth 8c is ge. The sum of the gaps in these magnetic paths is 2 g. Regarding the magnetic paths of the magnetic fluxes Fc and Fd, the length of the gap ga between the tooth 8a and the rotor 2 is g + e, and the length of the gap gb or gd between the rotor 2 and the teeth 8b or 8d is both g, and the sum of the gaps in these magnetic paths is 2 g + e.

  Various electromagnetic forces act on the rotor 2 by these magnetic fluxes. In FIG. 2, the force in the left-right direction on the paper is described. A rightward force acts on the rotor 2 due to the influence of the magnetic fluxes Fg and Fh. A rightward force acts on the rotor 2 even under the influence of the magnetic fluxes Fc and Fd. Under the influence of the magnetic fluxes Fi and Fj, a rightward force and a smaller but leftward force act on the rotor 2, and the leftward / rightward force on the paper surface is reduced. Under the influence of the magnetic fluxes Fa and Fb, both a rightward force and a leftward force act on the rotor 2. Since the windings 4a to 4d are wound inside the stator 1, the volume occupied by the windings 4a to 4d has an upper limit. Therefore, it is desirable to make the force caused by the magnetic flux induced from the windings 4a to 4d more effective. From these facts, it is considered desirable that the magnetic fluxes Fc and Fd that pass through the teeth 8a and 8b and the teeth 8a and 8d and act on the rotor 2 in the right direction on the paper surface are larger than the magnetic fluxes Fi and Fj.

  Since the strength (magnitude) of the magnetic flux is inversely proportional to the magnitude of the magnetic resistance, the condition for the magnetic fluxes Fc and Fd to be stronger than the magnetic fluxes Fi and Fj is 2g + e <g + h. When this is solved, g + e <h, but 0 ≦ e <g. Therefore, the condition for the magnetic fluxes Fc and Fd to always be larger than the magnetic fluxes Fi and Fj regardless of the eccentric state is g <h / 2. It becomes. From the above, in the present invention, the inner side (tip) of the teeth 8a to 8d of the stator 1 and the outer peripheral surface of the rotor 2 in a state where the center 9 of the stator 1 and the center 10 of the rotor 2 coincide with each other. The gap lengths ga to gd with respect to 12 are set to 1/2 or less with respect to the distance h between the inner peripheral surface 6 of the yoke 7 of the stator 1 and the outer peripheral surface 12 of the rotor 2. By configuring the rotating electric machine in this way, it is possible to balance the magnetic flux by adjusting the number of windings that is relatively small, and a rotating machine with low vibration and noise can be achieved within a practical adjustment range of the number of windings. It becomes feasible.

Embodiment 2. FIG.
FIG. 3 is a sectional view taken along the central axis of the rotating electrical machine according to the second embodiment of the present invention. The rotating electrical machine includes windings 4 a to 4 d wound around a core 3, a stator 1 accommodated in the housing 13, and supported by the housing 13, and bearings 14 and 15 so as to be able to rotate within the stator 1. The rotor 2 is supported and provided on the rotating shaft 16. The rotor 2 and the rotating shaft 16 are rotated in the stator 1 by the rotating magnetic field. FIG. 3 shows a capacitor motor, in which a capacitor 18 is housed in a housing 13 of a rotating electrical machine. The windings 4a to 4d are covered with an insulator 17, and a terminal 19 for measuring the terminal voltage of the windings 4a to 4d is embedded in the insulator 17 and installed. The end 19 is installed so that the terminal voltages of the windings 4a to 4d can be measured.

  Next, the effect of the terminal 19 will be described. In a rotating electrical machine in which there is no eccentricity between the stator 1 and the rotor 2, when the currents of the opposing windings 4a to 4d are equal, the terminal voltages of the windings 4a to 4d are equal. However, in a normal rotating electrical machine with eccentricity, when the currents of the opposing windings 4a to 4d are equal, the terminal voltages of the windings 4a to 4d are different. This is because the inductances of the windings 4a to 4d are different due to the influence of the eccentricity, and by using this principle, the eccentric state can be grasped from the terminal voltages of the windings 4a to 4d. As described above, the terminal 19 has been widely used in the past, and the terminal voltage is also used in many measurements. However, it is rarely possible to grasp the eccentric state from the terminal voltage. Further, the present invention is characterized in that the number of turns of the opposing windings 4a to 4d is made different so that the terminal voltages of the windings 4a to 4d are equal. As a means for changing the number of turns of the windings 4a to 4d, the number of turns of one conductive wire may be changed, or a winding different from the winding wound first may be added later. . With such a configuration, since the magnetic flux induced from the opposing windings is balanced, a rotating machine with low vibration and low noise can be realized at low cost.

It is a schematic explanatory drawing of the rotary electric machine by Embodiment 1 of this invention. It is a schematic explanatory drawing which shows the magnetic flux of the rotary electric machine by Embodiment 1 of this invention. It is a schematic sectional drawing of the rotary electric machine by Embodiment 2 of this invention.

Explanation of symbols

  1 Stator, 9, 10 center, 4a to 4d winding, Fa to Ff magnetic flux, 8a to 8d teeth, ga to gd gap, 7 yoke, g gap length, h distance, 19 terminals.

Claims (2)

A stator having a yoke and four teeth provided inside the yoke;
A rotating electrical machine comprising a rotor rotatably provided inside the stator,
The center of the stator and the center of the rotor are eccentric,
In the state where the center of the stator and the center of the rotor coincide with each other, the eccentricity is such that the gap length of the gap between the tip of the teeth of the stator and the rotor is the stator of the stator. An eccentricity from a configuration that is ½ or less of the distance between the yoke and the rotor;
The winding of the teeth on the side approaching the rotor due to the eccentricity is greater than the number of windings of the teeth on the side away from the rotor due to the eccentricity, and the windings facing the stator The number of winding turns is different between the pair of teeth facing in the radial direction so that the magnetic flux induced from
Rotating electric machine characterized by that.   The rotating electrical machine according to claim 1, further comprising a terminal capable of measuring an induced voltage generated in the winding.

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