JP4469187B2 - Permanent magnet motor - Google Patents

Description

  The present invention relates to a permanent magnet motor including a stator having a stator winding and a rotor having a permanent magnet housed in a magnet housing hole.

As an electric motor for driving a compressor such as an air conditioner (air conditioner) or a refrigerator, a permanent magnet electric motor including a rotor in which a permanent magnet is housed (embedded) in a magnet housing hole, that is, a rotor having a permanent magnet embedded structure ( Hereinafter, a “permanent magnet embedded type electric motor”) is used. The embedded permanent magnet electric motor is a motor that uses both magnet torque due to the magnetic flux of the permanent magnet and reluctance torque due to the saliency of the rotor.
A conventional permanent magnet embedded motor includes a rotor having a rotor core and a stator having a stator core. The rotor core has, for example, a magnet receiving hole formed in a rectangular shape perpendicular to the axial direction and a rectangular shape substantially perpendicular to the radial direction, or a cross-sectional shape perpendicular to the axial direction, with the convex side facing the center side. Convex-shaped magnet housing holes such as a facing arc shape are provided in each magnetic pole. And the permanent magnet in which the cross-sectional shape orthogonal to an axial direction was formed in the rectangular shape, the circular arc shape, etc. is accommodated in the magnet accommodation hole of each magnetic pole (embedded). As the permanent magnet, a ferrite magnet or a rare earth magnet is used.
Further, the stator core is provided with a tooth portion having a tip portion disposed via a gap (air gap) from the outer peripheral portion of the rotor core. A stator winding is disposed in a slot formed by the tooth portion.
By supplying power to the stator winding from a power supply source such as an inverter, the rotor rotates.

In recent years, downsizing of air conditioners, refrigerators, and the like has been demanded, and accordingly, downsizing of electric motors that drive compressors has been demanded. For example, a permanent magnet motor having an outer diameter of 90 mm is desired. In this case, it is necessary to reduce the size while maintaining the performance of the permanent magnet motor.
Here, the ferrite magnet has a characteristic that the magnetic flux density decreases as the temperature increases. On the other hand, rare earth magnets have a characteristic that the decrease in magnetic flux density is small even when the temperature increases.
Therefore, as a method of reducing the size of the permanent magnet motor, for example, a method of improving the efficiency of the permanent magnet motor by using a rare earth magnet as the permanent magnet, or improving the efficiency of the permanent magnet motor by changing the arrangement state of the permanent magnets. A method of making it possible is considered. However, using such a method does not improve the actual efficiency as expected. This is also caused by using a PWM control type inverter as a power supply source.
As a result of various investigations, the present inventors have configured the rotor and stator so that predetermined conditions are satisfied, such as the shape and dimensions of the rotor and stator, so that even when a PWM control type inverter is used as a power supply source. The present inventors have found that the efficiency of a permanent magnet motor can be improved.
Therefore, the present invention provides a permanent magnet motor that can improve efficiency even when a PWM control type inverter is used as a power supply source, and can be downsized while maintaining a predetermined performance. For the purpose.

  A first invention of the present invention for solving the above problem is a permanent magnet electric motor as set forth in claim 1.
  The permanent magnet motor according to claim 1 forms a slot in which the stator winding is accommodated, and a tooth portion having a tooth tip portion including a center portion and an end portion is provided in a portion facing the rotor. A stator, a rotor disposed at a gap between the tip of the teeth and a magnet, and a magnet housing hole for housing a permanent magnet provided in each magnetic pole, and an end wall of the magnet housing hole of each magnetic pole and the rotor A gap is provided between the outer peripheral portion of each of the two. As a result, a main magnetic pole portion is formed between the gap portions of the magnetic poles, and an inter-magnetic pole portion is formed between the gap portions of the adjacent magnetic poles.
  The distance B between the gap portions provided in the adjacent magnetic poles, the shortest distance A between the side surfaces of the adjacent teeth portions, the width C of the teeth portions, and the circumferential length D of the gap portions are B ≧ A and D It is configured to satisfy ≧ C. Thereby, since sufficient reluctance torque can be obtained, efficiency improves. Moreover, since the magnetic flux short circuit amount at the end of the permanent magnet accommodated in the magnet accommodation hole can be reduced, the effective magnetic flux amount can be increased, and the efficiency is improved. Furthermore, the torque pulsation is reduced by reducing the fluctuation of the reluctance torque, or the magnetic attraction force in the radial direction between the rotor and the stator is reduced by reducing the magnetic flux short-circuit amount at the end of the permanent magnet. Noise and vibration can be reduced. In addition, by providing an air gap between the magnet housing hole and the outer periphery of the rotor and disposing the permanent magnet away from the outer periphery of the rotor, the end of the permanent magnet is placed in a harmonic magnetic flux by PWM control or the like. Without being influenced by the above, the end heat generation of the permanent magnet can be reduced and the iron loss can be reduced. In this respect also, the efficiency can be improved.
  Further, the gap g between the outer periphery of the rotor and the tip of the teeth, and the shortest length L in the radial direction at each circumferential position of the gap are g × 0.2 ≦ L ≦ g × 0. 5 is satisfied. By satisfying g × 0.2 ≦ L, the short-circuit magnetic flux is reduced and the efficiency is improved. Furthermore, noise and vibration can be reduced by reducing the magnetic attractive force in the radial direction. By satisfying L ≦ g × 0.5, for example, when a recess formed in the outer periphery of the rotor is used as a gap, an increase in the resistance of the recess to the heat exchange medium is reduced, and loss in the recess is reduced. Therefore, the decrease in efficiency can be suppressed.
  Further, the opening angle θ of the effective magnetic pole portion between the gap portions of each magnetic pole is set to an angle at which the four magnetic teeth portions and the five teeth portions are alternately opposed to the effective magnetic pole portions. Thereby, an iron loss and a copper loss can be reduced and efficiency can be improved.
  The “end wall of the magnet housing hole” means an end wall near the outer periphery of the rotor. For example, when the magnet accommodation hole of each magnetic pole is configured by arranging a plurality of magnet accommodation holes in a row, the “end wall of the magnet accommodation hole” is arranged on the outer peripheral side of the rotor. Of the end walls of the magnet receiving hole portion, the end wall near the outer periphery of the rotor is shown.
  The second invention of the present invention is a permanent magnet motor as set forth in claim 2.
  In the permanent magnet motor according to the second aspect of the present invention, the gap is formed by the recess formed in the outer peripheral portion of the rotor. Thereby, a rotor can be formed easily.
  A third invention of the present invention is a permanent magnet motor as set forth in claim 3.
  In the permanent magnet motor according to the third aspect, the gap is formed so that the lengths in the radial direction are equal at each position in the circumferential direction. Thereby, a rotor can be formed easily. In addition, the description “the lengths in the radial direction are equal” includes the case where the lengths in the radial direction are substantially equal.
  A fourth invention of the present invention is a permanent magnet motor as set forth in claim 4.
  In the permanent magnet motor according to claim 4, the stator is provided with a passage penetrating in the axial direction. The stator outer diameter Ra, stator inner diameter Rb, slot cross-sectional area S, number of slots z, The total cross-sectional area G of the passage is [(Ra / 2). ² π-{(Rb / 2) ² π + G}] × 0.2 ≦ (S × z) ≦ [(Ra / 2) ² π-{(Rb / 2) ² π + G}] × 0.4. Thereby, efficiency can be improved more. As the passage, for example, a notch portion that is notched so as to penetrate the outer peripheral portion of the stator, a hole that is formed so as to penetrate the stator, and the like are used.
  The fifth aspect of the present invention is a permanent magnet motor as set forth in the fifth aspect.
  In the permanent magnet motor according to claim 5, the permanent magnet is accommodated in the magnet accommodation hole so that a gap is provided between the end wall of the magnet accommodation hole, and the end wall of the magnet accommodation hole and The bottom wall of the gap is formed substantially parallel to the outer periphery of the rotor.
  In addition, as described in claim 6, the permanent magnet motor can be reduced in size by setting the outer diameter of the stator to 90 mm.
  Furthermore, the permanent magnet motor of the present invention is used as a compressor driving motor such as an air conditioner or a refrigerator as described in claim 7 or claim 8, or as described in claim 9. By using it as a drive motor for an in-vehicle device, each device can be miniaturized.

If the permanent magnet electric motor according to any one of claims 1 to 9 is used, even if a PWM control type inverter is used as a power supply source, it is possible to reduce the size while maintaining a predetermined performance.

Embodiments of the present invention will be described below with reference to the drawings.
A schematic configuration of the permanent magnet motor of the present invention is shown in FIGS. 1 is a cross-sectional view, and FIG. 2 is a partially enlarged view of FIG.
The permanent magnet motor of the present invention is constituted by a rotor 10 and a stator 30.
The rotor 10 has a rotor core 11. The rotor core 11 is formed in a substantially cylindrical shape by laminating steel plates such as electromagnetic steel plates.
The stator 30 has a stator core (yoke part) 31. The stator core 11 is formed in a substantially cylindrical shape by laminating steel plates such as electromagnetic steel plates.

The rotor core 11 is provided with a shaft hole 12 through which the rotation shaft is inserted.
In addition, a plurality of magnet housing holes for housing (embedding) the permanent magnets are provided in parallel to the shaft hole 12. The magnet accommodation hole is provided for each magnetic pole. In the present embodiment, four magnet housing holes 21a to 21d are provided in the axial direction at intervals of 90 degrees.
Since the magnet housing holes 21a to 21d have the same structure, the magnet housing hole 21a will be described. In addition, the element code | symbol of the magnet accommodation holes 21b-21d replaces the alphabet a of the element code | symbol of the element corresponding to the magnet accommodation hole 21a, and uses it.
The magnet housing hole 21a is rotated by a linear inner wall 22a provided on the radial center side of the rotor core 11, a linear outer wall 23a provided on the radial outer peripheral side of the rotor core 11, and the outer wall 23a. End wall 24a, 25a, end wall 24a and inner wall 22a, end wall 25a and inner wall extending substantially parallel to the outer periphery of rotor core 11 from a position close to the outer periphery of child core 11 (substantially the same shape) 22a, formed by passage walls 26a and 27a that determine the width of the magnetic flux passage between the magnetic poles. The passage walls 26a and 27a may be omitted.
A gap is provided between the end walls 24 a and 25 a of the magnet housing hole 21 a and the outer periphery of the rotor core 11. In the present embodiment, the recesses (notches) 14a and 16a provided on the outer periphery of the rotor core 11 are used as the gaps. The recess 14a is formed by side walls 14a1, 14a3 and a bottom wall 14a2. The recess 16a has a similar shape.
In the present embodiment, the bottom walls 14a2, 16a2 of the recesses 14a, 16a, the end wall 24a, and the end wall 25a are provided substantially in parallel (having substantially the same shape). That is, the concave portions 14a to 14d and 16a to 16d are formed so that the lengths (depths) in the radial direction at the respective positions along the circumferential direction are substantially equal.

In each of the magnet housing holes 21a to 21d, permanent magnets 20a to 20d whose cross-sectional shape perpendicular to the axial direction is formed in a substantially rectangular shape are housed (embedded). Here, permanent magnets of different polarities are accommodated in the magnet accommodation holes of adjacent magnetic poles. For example, an N-pole permanent magnet 20a is accommodated in the magnet accommodation hole 21a (N pole on the outer wall 23a side and S pole on the inner wall 22a side), and an S-pole permanent magnet 20b is accommodated in the magnet accommodation hole 21b (outer wall 23b). Side is S pole, inner wall 22b side is N pole).
In the present embodiment, since the permanent magnets 20a to 20d whose cross-sectional shape perpendicular to the axial direction is formed in a substantially rectangular shape are used, the outer peripheral side of the rotor core 11 in the magnet housing holes 21a to 21d Gap 28a-28d and 29a-29d are provided in the both ends. The gaps 28a to 28d and 29a to 29d may be voids or may be filled with a nonmagnetic insulator such as resin.
For holding the permanent magnets 20a to 20d in the magnet housing holes 21a to 21d between the recesses 14a to 14d and the end walls 24a to 24d and between the recesses 16a to 16d and the end walls 25a to 25d. Connection portions (bridge portions) 17a to 17d and 18a to 18d are formed. Main magnetic pole portions (effective magnetic pole portions) 15a to 15d are formed between the concave portions 14a to 14d and 16a to 16d of the respective magnetic poles. Further, inter-magnetic pole portions 13a to 13d are formed between the concave portions 14a to 14d and 16a to 16d of the adjacent magnetic poles.

The stator core 31 is provided with a plurality of teeth portions (magnetic pole portions) 32 a to 32 n that protrude in a direction facing the rotor core 11. Tip portions (teeth tip portions) 33a to 33n are provided with a gap from the rotor core 11 at portions of the teeth portions 32a to 32n facing the rotor core 11.
In the slots 34a to 34n formed by the teeth portions 32a to 32n, stator windings are arranged, for example, in a distributed winding manner.
Further, the stator core 31 is provided with a passage through which refrigerant gas or the like passes in the axial direction. In FIG. 1, cutout portions 35 a to 35 n obtained by cutting out the outer peripheral portion of the stator core 31 are used as passages. A hole can also be used as a passage.

Next, the configuration of the first exemplary embodiment of the present invention will be specifically described.
Consider the permanent magnet embedded motor shown in FIGS.
In the permanent magnet embedded type electric motor shown in FIGS. 3 and 4, the rotor core 211 of the rotor 210 is provided with magnet housing holes 221 a to 221 d for housing the permanent magnets 220 a to 220 d for each magnetic pole. (In FIGS. 3 and 4, every 90 degrees). The stator core 231 of the stator 230 is provided with teeth portions 232a to 232n that form slots 234a to 234n. The tooth portions 232a to 232n are provided with tooth tip portions 233a to 233n that are disposed to face the rotor core 211 with a gap.
Here, when the interval between the magnet receiving holes of adjacent magnetic poles (for example, the shortest distance between the magnet receiving holes 221a and 221b) is B, and the shortest distance between the side surfaces of the adjacent teeth portions 232a to 232n is A, Consider the case where the relationship of [B <A] is set.

In this case, the positional relationship between the rotor 210 and the stator 230 shown in FIG. 3 (the portion between the magnet receiving holes 221a and 221b of the adjacent magnetic poles (passage portion between the magnetic poles) faces the teeth portion 232a). In this case, the magnetic flux φ1 flows through the central portion of the tooth tip 233a in the path between the magnetic poles between the magnet receiving holes 221a and 221b. Since the magnetic flux φ1 at this time is large, a large reluctance torque is generated.
On the other hand, the positional relationship between the rotor 210 and the stator 230 shown in FIG. 4 (the portion between the magnet receiving holes 221a and 221b of the adjacent magnetic poles (the passage portion between the magnetic poles) is intermediate between the teeth portions 232a and 232b. In the path between the magnetic poles between the magnet receiving holes 221a and 221b, the magnetic flux φ2 via the end of the tooth tip 233a and the magnetic flux φ3 via the end of the tooth tip 233b Flows. Here, since the cross-sectional areas of the end portions of the tooth tip portions 233a to 233n are small, the tooth tip portions 233a to 233n are magnetically saturated only by a small amount of magnetic flux flowing, and the magnetic flux does not easily flow. Therefore, the sum of the magnetic fluxes φ2 and φ3 is smaller than the magnetic flux φ1, and the reluctance torque generated is also small.
As described above, when the reluctance torque increases or decreases (fluctuates), torque pulsation increases, and vibration and noise resulting from torque pulsation increase.

On the other hand, in the first embodiment, as shown in FIGS. 5 and 6, the distance between the recesses 14a to 14d and 16a to 16d provided in the adjacent magnetic poles (the circumference of the inter-pole portions 13a to 13n). (Length in the direction) B and the shortest distance A between the side surfaces of the adjacent tooth portions 32a to 32n are configured to satisfy [B ≧ A].
In this case, when the rotor 10 and the stator 30 are in the positional relationship shown in FIG. 5 (the inter-magnetic pole portion 13a faces the teeth portion 32a), the gap between the magnet receiving holes 21a and 21b of the adjacent magnetic poles In the path portion between the magnetic poles, a magnetic flux φ4 flows through the center portion of the tooth tip portion 33a. Since the magnetic flux φ4 at this time is large, a large reluctance torque is generated.
Further, when the rotor 10 and the stator 30 are in the positional relationship shown in FIG. 6 (the inter-magnetic pole portion 13a corresponds to the intermediate portion between the teeth portions 32a and 32b), the inter-magnetic pole portion 13a is connected to the tooth tip portion 33a. And the center of the tooth tip 33b. For this reason, the magnetic flux φ5 passes through the central portion of the tooth tip 33a (without passing through the end of the tooth tip 33a) in the inter-pole passage portion between the magnet receiving holes 21a and 21b of the adjacent magnetic poles, Magnetic flux φ6 flows through the central portion of the tooth tip portion 33b (without passing through the end portion of the tooth tip portion 33b). Since the magnetic fluxes φ5 and φ6 flow without passing through the ends of the teeth tip portions 33a and 33b, the sum of the magnetic fluxes φ5 and φ6 is large, and the generated reluctance torque is also large.

Thus, in the first embodiment, the distance (the length between the magnetic poles) B between the concave portions (gap portions) provided in the adjacent magnetic poles, and the shortest distance A between the side surfaces of the adjacent tooth portions are as follows. , [B ≧ A] is satisfied.
Thereby, since a large reluctance torque can always be generated regardless of the position of the rotor, the efficiency is improved.
Furthermore, since fluctuations in reluctance torque are reduced, torque pulsation can be reduced, and vibration and noise caused by torque pulsation can be reduced.

Further, when no gap is provided between the magnet housing holes 221a to 221d of the magnetic poles and the outer peripheral portion of the rotor core 211, the permanent magnets 220a to 220a housed in the magnet housing holes 221a to 221d. A path through which a short-circuit magnetic flux flows may be formed between 220d and the respective tooth tip portions 233a to 233n provided on the stator core 231. For example, as shown in FIG. 7, a short-circuit magnetic flux φ7 flows from the north pole of the permanent magnet 220a housed in the magnet housing hole 221a to the south pole of the permanent magnet 220a via the tooth tip 233a.
When a short-circuit magnetic flux flows between the permanent magnets 220a to 220d housed in the magnet housing holes 221a to 221d and the tooth tip portions 233a to 233n, the effective magnetic flux amount decreases. For this reason, a torque reduces and efficiency falls.

On the other hand, in the present embodiment, as shown in FIG. 8, the recesses 14 a to 14 d are provided between the end walls 24 a to 24 d and 25 a to 25 d of the magnet housing holes 21 a to 21 d and the outer peripheral portion of the rotor core 11. 16a to 16d are provided as gaps.
Furthermore, in this embodiment, when D is the circumferential length of the recesses 14a to 14d and 16a to 16d, and C is the width (distance between the side surfaces) of the tooth portions 32a to 32n, [D ≧ C] is satisfied. It is configured to satisfy.
Here, when configured to satisfy [D ≧ C], as shown in FIG. 8, the short-circuit magnetic flux φ8 may flow through the end of the tooth tip 33a. However, as described above, since the cross-sectional area of the end portions of the tooth tip portions 33a to 33n is small, the tooth tip portions 33a to 33n are magnetically saturated only by a small amount of magnetic flux flowing.
For this reason, if it is comprised so that [D> = C] may be satisfied, the quantity of the short circuit magnetic flux which flows through the teeth front-end | tip parts 33a-33n can be reduced.

As described above, in the first embodiment, a recess is provided as a gap between the end wall of the magnet housing hole and the outer periphery of the rotor core, and the length of the recess in the radial direction is further provided. D and the width (distance between the side surfaces) C of the teeth portion are configured to satisfy [D ≧ C].
Thereby, since the amount of short-circuit magnetic flux flowing between the N pole and the S pole of the permanent magnet accommodated in the magnet accommodation hole can be reduced via the tooth tip provided in the stator core, Efficiency can be improved by increasing the amount of effective magnetic flux.
Moreover, the magnetic attraction force in the radial direction between the stator core and the rotor core is reduced by reducing the short-circuit magnetic flux amount. Thereby, the vibration and noise which generate | occur | produce due to the magnetic attraction force of radial direction can be reduced.

In the first embodiment, the configuration is such that the circumferential length D of the recess and the width (distance between the side surfaces) C of the tooth portion satisfy [D ≧ C], whereby the short-circuit magnetic flux of the permanent magnet. Although the amount is reduced, the amount of short-circuit magnetic flux can be further reduced.
FIG. 9 shows the configuration of the second embodiment that can further reduce the amount of short-circuit magnetic flux of the permanent magnet.
Since the basic configuration of the second embodiment is the same as that shown in FIGS. 1 and 2, only the configuration different from the first embodiment will be described.
In the present embodiment, the circumferential directions of the recesses 14a to 14d and 16a to 16d provided between the end walls 24a to 24d and 25a to 25d of the magnet housing holes 21a to 21d and the outer periphery of the rotor core 11 are provided. Is D, and the circumferential length of the teeth tip portions 33a to 33n (the length of the rotor core 11 in the moving direction) is H, [D ≧ H] is satisfied. .
In this case, the short-circuit magnetic flux flowing through the end portion of the tooth tip portion 33a can be further reduced than in the case shown in FIG.
Thereby, the effective magnetic flux amount can be further increased, and the efficiency can be further improved.

Next, a third embodiment will be described.
In the third embodiment, a method of improving efficiency by setting the radial length (depth) of the gap in a predetermined range is used.
Here, as shown in FIG. 12, the gap (air gap) between the outer periphery of the rotor core 11 and the tooth tip 33a is g, and the lengths (depths) of the recesses 14a to 14d and 16a to 16d in the radial direction. S) is L.
The lengths (depths) of the recesses 14a to 14d and 16a to 16d in the radial direction are indicated by, for example, the distance between the inter-magnetic pole portion 13a or the effective magnetic pole portion 15a and the bottom wall 14a2 of the recess 14a (see FIG. 2).
In addition, when the radial length (depth) of the gap is not equal at each position in the circumferential direction (for example, the gap shown in FIGS. 20 to 23), the radial length (depth) of the gap is shown. The shortest length (the length of the shallowest portion) is defined as the length (depth) L of the gap.

Normally, when an electric motor is incorporated into a compressor or the like, the rotor 10 may be attached with a slight shift from the center due to assembly tolerances or the like. When the center of the rotor 10 is shifted and attached, the tooth portions 32a to 32n (including the tooth tip portions 33a to 33n) on the side where the gap (air gap) between the rotor 10 and the stator 30 is reduced. It may be deformed by magnetic attraction force and noise may be generated.
However, in this Embodiment, since the recessed parts 14a-14d and 16a-16d are provided in the outer peripheral part of the rotor core 11, the magnetic attraction force which acts on the teeth parts 32a-32n can be reduced. Thereby, the noise generated due to the deformation of the teeth portions 32a to 32n due to the magnetic attractive force can be reduced.
The length (depth) L in the radial direction of the recesses 14a to 14d and 16a to 16d formed in the outer peripheral portion of the rotor 10, and the gap (air) between the outer peripheral portion of the rotor 10 and the tooth tip portions 32a to 32n. The relationship between the ratio (L / g) to the gap (g) and the noise is shown in FIG.
From FIG. 10, it can be seen that the noise generated is reduced by setting (L / g) to 0.2 or more.

In addition, when the length (depth) L in the radial direction of the recesses 14a to 14d and 16a to 16d and the air gap g are in a relationship of [(L / g) <0.2], [D ≧ C described above] ] Or [D ≧ H], even when the relationship [D ≧ H] is satisfied, as shown in FIG.
When the amount of short-circuit magnetic flux flowing from the N pole of the permanent magnets 20a to 20d accommodated in the magnet accommodation holes 21a to 21d to the S pole of the permanent magnets 20a to 20d via the teeth tip portions 33 to 33n increases, the effective magnetic flux amount The efficiency decreases because of the decrease.
Also in this respect, the efficiency can be improved by setting (L / g) to 0.2 or more.

In addition, an electric motor used in a compressor or the like is operated under high pressure. When operating in such an environment, if the length of the recess in the outer peripheral portion of the rotor is long (deep) in the radial direction, as shown in FIG. 13, the heat exchange medium (for example, refrigerant) The resistance increases, and the loss in the concave portion during the rotation of the rotor increases. That is, efficiency is reduced.
The ratio (L / g) of the length (depth) L in the radial direction of the recess formed in the outer peripheral portion of the rotor and the gap (air gap) g between the outer peripheral portion of the rotor and the tip of the teeth. The relationship with the resistance of the heat exchange medium (refrigerant) is shown in FIG.
From FIG. 11, by setting (L / g) to 0.5 or less, the resistance of the heat exchange medium can be kept small, and the increase in loss in the recesses 14a to 14d and 16a to 16d is suppressed. I understand that.

As described above, in the present embodiment, the gap (air gap) g between the outer peripheral portion of the rotor and the tip of the teeth, and the end wall of the magnet housing hole and the outer peripheral portion of the rotor core are provided. The length (depth) L in the radial direction of the recessed portion is configured to satisfy [g × 0.2 ≦ L ≦ g × 0.5].
Thereby, since the quantity of the short circuit magnetic flux through a teeth front-end | tip part can be reduced, efficiency can be improved.
Moreover, since the loss due to the resistance of the recess with respect to the heat exchange medium can be reduced, the efficiency can be improved.
Furthermore, since the radial magnetic attractive force acting between the stator and the rotor can be reduced, noise caused by the magnetic attractive force acting between the stator and the rotor can be reduced. it can.

  In the third embodiment, the recess formed in the outer peripheral portion of the rotor is used as the gap provided between the end wall of the magnet housing hole and the outer peripheral portion of the rotor core. Besides, a hole formed between the end wall of the magnet housing hole and the outer peripheral portion of the rotor core can also be used. In this case, the condition [L ≦ g × 0.5] described above is not applied. The allowable maximum value of L in this case is determined by the design conditions of the permanent magnet motor, for example, the outer diameter of the rotor core, the arrangement conditions of the magnet housing holes for housing the permanent magnets necessary for obtaining predetermined characteristics, and the like. The

Next, a fourth embodiment will be described.
The fourth embodiment uses a method of improving efficiency by setting the opening angle θ of the effective magnetic pole portions 15a to 15d of each magnetic pole of the rotor core 11 within a predetermined range.
The open angle θ of the effective magnetic pole portions 15a to 15d of each magnetic pole means an angle formed by a straight line connecting the center portion P of the rotor core and both ends of each effective magnetic pole portion, as shown in FIG. And
In the present embodiment, the opening angle θ of the effective magnetic pole portions 15a to 15d is represented by the relationship between the opening angle θ of each of the effective magnetic pole portions 15a to 15d and the teeth portions 32a to 32n.
The relationship between the opening angle θ of each of the effective magnetic pole portions 15a to 15d and the tooth portions 32a to 32n can be expressed by the number of the tooth portions 32a to 32n facing the effective magnetic pole portions 15a to 15d.
Here, the end portion of the tooth tip portion has a small cross-sectional area, and magnetic saturation occurs only when a small amount of magnetic flux flows. Therefore, in the present embodiment, the number of the tooth portions facing the effective magnetic pole portion is such that the central portion of the tooth tip portion (the portion corresponding to the columnar main body portion of the tooth portion) faces the effective magnetic pole portion. Expressed as the number of teeth.

FIGS. 14 to 16 show the results of obtaining the magnetic flux density, the electromotive force constant, and the efficiency for the patterns A to D having different opening angles θ of the effective magnetic pole portions 15a to 15d.
Patterns A to D are two and three teeth portions, three and four teeth portions, four and five teeth portions, and five alternately on the effective magnetic pole portion as the rotor rotates. The opening angle θ of the effective magnetic pole portion is set so that the six teeth portions face each other.
For example, in the pattern C, the opposing state of the effective magnetic pole portion 15a and the teeth portions 32a to 32n changes in order as shown in FIGS. 17A to 17C as the rotor rotates. In FIGS. 17A to 17C, the rotor is assumed to rotate clockwise.
For example, as shown in FIG. 17A, four teeth portions 32a to 32d face the effective magnetic pole portion 15a at an arbitrary time. Next, as shown in FIG. 17B, the five teeth portions 32a to 32e face the effective magnetic pole portion 15a. Next, as shown in FIG.17 (c), the four teeth parts 32b-32e oppose the effective magnetic pole part 15a.
In the patterns A to D, the amount of permanent magnet used and the structure of the stator are the same.

The magnetic flux densities for the patterns A to D are shown in FIG.
When the number of teeth portions facing the effective magnetic pole portion is small, the teeth magnetic flux density increases and the iron loss increases. FIG. 14 shows that patterns C and D have low teeth density and small iron loss.
FIG. 15 shows electromotive force constants for patterns A to D.
The higher the electromotive force constant, the greater the electromotive force, and the greater the amount of magnetic flux close to the d-axis direction (the direction of the line connecting the central portion of the effective magnetic pole portion and the rotor core), the higher the electromotive force. When the electromotive force is high, the driving current is reduced and the copper loss is reduced. From FIG. 15, it can be seen that the electromotive force constants of patterns A, B, and C in which the magnetic flux contributing to the electromotive force is concentrated on a specific tooth portion are high.
The efficiency (motor efficiency) for the patterns A to D is shown in FIG.
From FIG. 16, it can be seen that the efficiency of the pattern C is good because the teeth magnetic flux density is small, the iron loss is small, the electromotive force constant is large, and the copper loss is small.

  As described above, it is possible to reduce iron loss and copper loss by setting the opening angle θ of the effective magnetic pole portion so that four and five teeth portions are opposed to the effective magnetic pole portion alternately. , Can improve the efficiency.

Next, a fifth embodiment will be described.
In the fifth embodiment, a method of improving efficiency by setting the dimension of the stator core 31 within a predetermined range is used. As a method of determining the dimension of the stator core 31, for example, the cross-sectional area perpendicular to the axial direction of the stator core 31 shown in FIG. 1 (stator core cross-sectional area) and the stator core 31 are provided. The ratio of the total slot cross-sectional area to the sum of the total area of the cross sections perpendicular to the axial direction of the slots 34a to 34n formed by the teeth portions 32a to 32n (total slot cross-sectional area) is used.
In the shape of the stator core 31 shown in FIG. 1, the sum of the stator core cross-sectional area and the slot total cross-sectional area is represented by [(Ra / 2) ² π − {(Rb / 2) ² π + G}]. . Here, Ra is the outer diameter of the stator core 31, Rb is the inner diameter of the stator core 31, and G is the area of a cross section perpendicular to the axial direction of the notches 35a to 35n (passages) provided in the stator core 31. Indicates the sum of The total slot cross-sectional area is indicated by [S × z]. Here, S represents the area of the cross section perpendicular to the axial direction of the slots 34a to 34n, and z represents the number of slots.
Then, the slot total cross-sectional area [S × z] is changed to a sum of the stator core cross-sectional area and the total slot cross-sectional area [(Ra / 2) ² π − {(Rb / 2) ² π + G}] with various coefficients ( The efficiency when the ratio is multiplied is obtained, and a range of coefficients that can improve the efficiency is determined.

The outer diameter Ra of the stator is 90 mm, the inner diameter Rb of the stator is 51 mm, the total sectional area G of the notches 35a to 35n is 275.4 mm ² , the number of slots n is 24, and the slot sectional area S is changed by changing the coefficient. The results of determining the copper loss, iron loss, efficiency, etc. in the case of this are shown in the table of FIG. In addition, each value shown in FIG. 19 is calculated | required in the state of the same input electric power, the same rotation speed, and the same torque.
FIG. 18 is a graph showing the relationship between the copper loss, iron loss, and efficiency with respect to the slot cross-sectional area S shown in FIG.
18 and 19, when the slot cross-sectional area S is small (coefficient is smaller than 0.2), the wire diameter of the stator windings disposed in the slots 34a to 34n becomes too thin, and the copper loss increases. I understand that It can also be seen that when the slot cross-sectional area S is large (the coefficient is larger than 0.4), the current increases to cover the efficiency reduction due to the magnetic saturation of the stator core 31, and the copper loss increases.
From the above, the total slot cross-sectional area [S / z] is set to [[(Ra / 2) ² π − {(Rb / 2) ² π + G}] × 0.2 ≦ S · z ≦ [(Ra / 2). ) ² [pi - by ^{{(Rb / 2) 2 π} + G}] × 0.4] is configured to be satisfied, it is possible to reduce the copper loss and iron loss, thereby improving the efficiency.
This embodiment can also be applied to the case where a hole formed in the stator core is used as a passage.

In the above embodiment, a recess having the same radial length (depth) is provided as a gap between the end wall of the magnet housing hole and the outer periphery of the rotor core. It may be a hole provided between the end wall of the magnet housing hole and the outer periphery of the rotor core.
Also, the shape and number of recesses and holes provided between the end wall of the magnet housing hole and the outer periphery of the rotor core can be variously changed.
Moreover, the shape of the magnet accommodation hole provided in a rotor core and the shape of the permanent magnet accommodated in a magnet accommodation hole are variously changeable.
20 to 23 show other embodiments of the rotor.
20A to 23A show a rotor having a recess provided between the end wall of the magnet housing hole and the outer periphery of the rotor core, and FIGS. 20B to 23B show magnets. The rotor which provided the hole between the edge part wall of an accommodation hole and the outer peripheral part of a rotor core is shown.

The configuration of the embodiment shown in FIGS. 20 to 23 will be described below.
The rotor shown in FIG. 20A has a central portion 43a and outer peripheral portions 42a and 44a at each magnetic pole of the rotor core 40, and the cross-sectional shape perpendicular to the axial direction is such that the convex portion side faces the central side. A magnet housing hole 41a having a trapezoidal shape is formed. In addition, recesses 45 a and 46 a are formed between the end wall of the magnet housing hole 41 a and the outer periphery of the rotor core 40. The side walls of the recesses 45a and 46a are formed in parallel with the outer walls (or inner walls) of the outer peripheral portions 42a and 44a of the magnet housing hole 41a. And the permanent magnets 47a, 48a, and 49a whose cross-sectional shape orthogonal to an axial direction has a substantially rectangular shape are accommodated in the center part 43a and the outer peripheral parts 42a and 44a of the magnet accommodation hole 41a.
The rotor shown in FIG. 20B has the same magnet accommodation hole 51a and permanent magnets 57a to 59a as the rotor core 40 shown in FIG. Holes 55 a and 56 a are formed between the end wall on the outer peripheral side of the rotor core 50 of the outer peripheral parts 52 a and 54 a of the hole 51 a and the outer peripheral part of the rotor core 50.

The rotor shown in FIG. 21 (a) has both sides of the center portion 62a so that each magnetic pole of the rotor core 60 has a cross-sectional shape perpendicular to the axial direction and a C-shape with the convex side facing the center. 1st and 2nd magnet accommodation holes 61a and 63a are formed in this. In addition, recesses 64 a and 65 a are formed between the end wall of the first and second magnet housing holes 61 a and 63 a on the outer peripheral side of the rotor core 60 and the outer peripheral portion of the rotor core 60. The end walls on the central portion 62a side of the first and second magnet housing holes 61a and 63a are formed substantially in parallel. The first and second magnet housing holes 61a and 63a accommodate permanent magnets 66a and 67a having a substantially rectangular cross section perpendicular to the axial direction.
The rotor shown in FIG. 21B has first and second magnet housing holes 71a and 73a, permanent magnets 76a and 76a similar to the rotor core 60 shown in FIG. 77a, and holes 74a and 75a are formed between the end wall on the outer peripheral side of the rotor core 70 of the first and second magnet housing holes 71a and 73a and the outer peripheral portion of the rotor core 70. .

The rotor shown in FIG. 22A has first and second accommodating portions 82a and 83a at each magnetic pole of the rotor core 80, and the cross-sectional shape perpendicular to the axial direction is such that the convex side faces the center side. A magnet housing hole 81a having a square shape is formed. In addition, recesses 84 a and 85 a are formed between the end wall of the magnet housing hole 81 a and the outer periphery of the rotor core 80. Permanent magnets 86a and 87a having a substantially rectangular cross section perpendicular to the axial direction are accommodated in the first and second accommodating portions 82a and 83a of the magnet accommodating hole 81a.
The rotor shown in FIG. 22 (b) has magnet accommodation holes 91a and permanent magnets 96a and 97a similar to the rotor core 70 shown in FIG. 22 (a) at each magnetic pole of the rotor core 90, and magnet accommodation. Holes 94 a and 95 a are formed between the end wall of the hole 91 a and the outer periphery of the rotor core 90.

In the rotor shown in FIG. 23 (a), each magnetic pole of the rotor core 100 is formed with a magnet housing hole 101a having a cross-sectional shape perpendicular to the axial direction and an arc shape with the convex side facing the center. . Further, recesses 102 a and 103 a are formed between the end wall of the magnet housing hole 101 a and the outer periphery of the rotor core 100. In the magnet housing hole 101a, a permanent magnet 104a having a circular cross section perpendicular to the axial direction is housed.
The rotor shown in FIG. 23B has a magnet housing hole 111a and a permanent magnet 114a similar to the rotor core 100 shown in FIG. 23A at each magnetic pole of the rotor core 110, and the magnet housing hole 111a. The holes 112 a and 113 a are formed between the end wall of the rotor and the outer peripheral portion of the rotor core 110.

The present invention is not limited to the configuration described in the embodiment, and various changes, additions, and deletions are possible.
For example, although each magnetic pole of the rotor is composed of a single layer, each magnetic pole may be composed of multiple layers.
Moreover, the shape of a magnet accommodation hole and the shape of a permanent magnet can be variously changed. Further, the material of the permanent magnet can be variously changed.
Also, the size of the stator and the rotor can be variously changed.
Moreover, although demonstrated about the case where it uses for a compressor, the permanent-magnet motor of this invention can be used as an electric motor of various apparatuses, such as a vehicle-mounted apparatus driven with a refrigerator and an electric motor.

It is sectional drawing which shows schematic structure of the permanent magnet electric motor of this invention. It is the elements on larger scale of FIG. It is a figure explaining the structure and effect | action of the 1st Embodiment of this invention. It is a figure explaining the structure and effect | action of the 1st Embodiment of this invention. It is a figure explaining the structure and effect | action of the 1st Embodiment of this invention. It is a figure explaining the structure and effect | action of the 1st Embodiment of this invention. It is a figure explaining the structure and effect | action of the 1st Embodiment of this invention. It is a figure explaining the structure and effect | action of the 1st Embodiment of this invention. It is a figure explaining the structure and effect | action of the 2nd Embodiment of this invention. It is a figure explaining the effect of the 3rd Embodiment of this invention. It is a figure explaining the effect of the 3rd Embodiment of this invention. It is a figure explaining the structure and effect | action of the 3rd Embodiment of this invention. It is a figure explaining the structure and effect | action of the 3rd Embodiment of this invention. It is a figure explaining the effect of the 4th Embodiment of this invention. It is a figure explaining the effect of the 4th Embodiment of this invention. It is a figure explaining the effect of the 4th Embodiment of this invention. It is a figure explaining the structure and effect | action of the 4th Embodiment of this invention. It is a figure explaining the effect of the 5th Embodiment of this invention. It is a figure explaining the effect of the 5th Embodiment of this invention. It is a figure which shows other embodiment of a rotor. It is a figure which shows other embodiment of a rotor. It is a figure which shows other embodiment of a rotor. It is a figure which shows other embodiment of a rotor.

Explanation of symbols

10, 210 Rotor 11, 40, 50, 60, 70, 80, 90, 100, 110, 211 Rotor core 14a-14d, 16a-16d, 45a, 46a, 64a, 65a, 84a, 85a, 102a, 103a Concave (void)
15a-15d Effective magnetic pole portions 21a-21d, 41a, 51a, 61a, 63a, 71a, 73a, 81a, 91a, 101a, 111a, 221a-221d Magnet housing holes 20a-20d, 47a-49a, 57a-59a, 66a, 67a, 76a, 77a, 86a, 87a, 96a, 97a, 104a, 114a, 220a to 220d Permanent magnets 30, 230 Stator 31 and 231 Stator cores 32a to 32n, 232a to 232n Teeth portions 33a to 33n, 233a to 233n Teeth tip 34a-34n, 234a-234n Slot 35a-35n Notch 55a, 56a, 74a, 75a, 94a, 95a, 112a, 113a Hole

Claims (9)

A stator in which a slot for accommodating a stator winding is formed and a tooth portion having a tooth tip portion including a center portion and an end portion is provided in a portion facing the rotor, and a tooth tip portion and a gap are interposed A permanent magnet electric motor including a rotor provided with a magnet housing hole for housing a permanent magnet in each magnetic pole,
A gap is provided between the end wall of the magnet housing hole and the outer periphery of the rotor,
When the distance of the gap provided in the adjacent magnetic pole is B, the shortest distance between the side surfaces of the adjacent teeth is A, the width of the teeth is C, and the circumferential length of the gap is D,
B ≧ A, D ≧ C
It is configured to satisfy
When the gap between the outer periphery of the rotor and the tip of the teeth is g, and the shortest length in the radial direction at each circumferential position of the gap is L,
g × 0.2 ≦ L ≦ g × 0.5
Is configured to satisfy
In addition, the permanent magnet motor in which the opening angle θ of the effective magnetic pole portion between the gap portions of each magnetic pole is set to an angle at which the four tooth portions and the five tooth portions are alternately opposed to the effective magnetic pole portion. The permanent magnet motor according to claim 1 , wherein the gap provided between the end wall of the magnet housing hole and the outer peripheral portion of the rotor is a recess formed in the outer peripheral portion of the rotor. Permanent magnet motor. 3. The permanent magnet motor according to claim 1 , wherein the gap is formed so that the radial lengths at the circumferential positions are equal. The permanent magnet motor according to any one of claims 1 to 3 ,
The stator is provided with a passage that penetrates in the axial direction,
When the outer diameter of the stator is Ra, the inner diameter of the stator is Rb, the slot cross-sectional area is S, the number of slots is z, and the total cross-sectional area of the passage is G,
[(Ra / 2) ² π − {(Rb / 2) ² π + G}] × 0.2 ≦ (S × z)
≦ [(Ra / 2) ² π − {(Rb / 2) ² π + G}] × 0.4
Permanent magnet motor that is configured to satisfy. 5. The permanent magnet motor according to claim 1 , wherein a permanent magnet is accommodated in the magnet accommodation hole so that a gap is provided between the end wall of the magnet accommodation hole and a magnet. A permanent magnet motor in which the end wall of the housing hole and the bottom wall of the gap are formed substantially parallel to the outer periphery of the rotor. The permanent magnet motor according to claim 1 , wherein the stator has an outer diameter of 90 mm. It is an air conditioner which adjusts indoor temperature using the heat exchange medium compressed with the compressor, Comprising: The air conditioner using the permanent magnet motor in any one of Claims 1-6 as a drive motor of a compressor. It is a refrigerator which adjusts the temperature in a store | warehouse | chamber using the heat exchange medium compressed with the compressor, Comprising: The refrigerator using the permanent magnet motor in any one of Claims 1-6 as a drive motor of a compressor. An in-vehicle device driven by an electric motor, wherein the in-vehicle device uses the permanent magnet electric motor according to any one of claims 1 to 6 .

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