JP3533209B2 - Permanent magnet motor - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a permanent magnet electric motor provided with a stator having a stator winding and a rotor having a permanent magnet housed in a magnet housing hole.

[0002]

2. Description of the Related Art As a motor for driving a compressor such as an air conditioner (air conditioner) or a refrigerator, a rotor having a permanent magnet housed (embedded) in a magnet housing hole, that is, a rotor having a permanent magnet embedded structure is used. A provided permanent magnet electric motor (hereinafter, referred to as "permanent magnet embedded electric motor") is used. The permanent magnet embedded type electric motor is a motor that utilizes 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 electric motor includes a rotor having a rotor core and a stator having a stator core. In the rotor core, for example, a sectional shape perpendicular to the axial direction, a magnet accommodating hole formed in a rectangular shape substantially perpendicular to the radial direction, or a sectional shape perpendicular to the axial direction, the convex side is the central side Each magnetic pole is provided with a magnet housing hole having a convex shape such as a facing arc shape. A permanent magnet having a rectangular or arcuate cross-section perpendicular to the axial direction is housed (embedded) in the magnet housing hole of each magnetic pole. Ferrite magnets and rare earth magnets are used as permanent magnets. Further, the stator core is provided with a tooth portion whose front end portion is arranged with a gap (air gap) from the outer peripheral portion of the rotor core. The stator winding is arranged in the slot formed by the tooth portion. The rotor rotates by supplying power to the stator winding from a power supply source such as an inverter.

[0003]

In recent years, there has been a demand for downsizing of air conditioners, refrigerators and the like, and accordingly, there has been a demand for downsizing of an electric motor for driving a compressor. For example, a permanent magnet electric 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 rises. On the other hand, the rare earth magnet has a characteristic that the magnetic flux density is less likely to decrease even when the temperature rises. Therefore, as a method of miniaturizing 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. The method of making it possible is considered. However, even if such a method is used, the actual efficiency is not improved as much as expected. This is also due to the use of a PWM control type inverter as a power supply source. As a result of various studies, the inventors of the present invention configured the rotor and the stator such that the shapes and dimensions of the stator and the like are satisfied so that a PWM control type inverter is used as a power supply source. Found that the efficiency of a permanent magnet motor can be improved. Therefore, the present invention can improve efficiency even when a PWM control type inverter is used as a power supply source.
Therefore, it is an object of the present invention to provide a permanent magnet electric motor that can be downsized while maintaining a predetermined performance.

[0004]

A first invention of the present invention for solving the above problems is a permanent magnet electric motor as set forth in claim 1. In the permanent magnet electric motor according to claim 1, a gap is provided between the end wall of the magnet housing hole and the outer periphery of the rotor, and the distance B between the gaps provided in the adjacent magnetic poles, Shortest distance A between the side surfaces of adjacent teeth, width C of teeth, and circumferential length D of voids
Are configured to satisfy [B ≧ A] and [D ≧ C]. As a result, a sufficient reluctance torque can be obtained, which improves efficiency. In addition, since the amount of magnetic flux short circuit at the end of the permanent magnet housed in the magnet housing hole can be reduced, the effective amount of magnetic flux can be increased and the efficiency is improved. Furthermore, torque pulsation is reduced by reducing fluctuations in reluctance torque, or
Since the magnetic attraction force in the radial direction between the rotor and the stator is reduced by reducing the amount of magnetic flux short circuit at the end of the permanent magnet, noise and vibration can be reduced. In addition, by providing a gap between the magnet housing hole and the outer peripheral portion of the rotor and disposing the permanent magnet away from the outer peripheral portion of the rotor, the end portion of the permanent magnet has a harmonic magnetic flux generated by PWM control or the like. It is possible to reduce iron loss by reducing end heat generation of the permanent magnet without being affected by. Also in this respect, the efficiency can be improved. The “end wall of the magnet housing hole” means an end wall near the outer peripheral portion of the rotor. For example, when the magnet housing hole of each magnetic pole is formed by arranging a plurality of magnet housing hole portions in a row, the “end wall of the magnet housing hole” is arranged on the outer peripheral side of the rotor. Among the end walls of the magnet housing hole, the end wall near the outer peripheral portion of the rotor is shown. Further, in the permanent magnet electric motor according to claim 1, rotation is
Gap between the outer periphery of the child and the tip of the tooth,
The minimum length L of the radial length at each position in the circumferential direction is
Configured to satisfy [g × 0.2 ≦ L ≦ g × 0.5]
Has been done. By satisfying [g × 0.2 ≦ L]
Therefore, the short circuit magnetic flux is reduced and the efficiency is improved. In addition,
Noise and vibration are reduced by reducing the magnetic attraction force in the Al direction.
Can be reduced. Must satisfy [L ≦ g × 0.5]
By, for example, the recess formed on the outer peripheral portion of the rotor is emptied.
When used as a gap, the resistance of the recess to the heat exchange medium.
It reduces the increase in drag and suppresses the increase in loss in the recess.
Therefore, it is possible to suppress a decrease in efficiency.
A second invention of the present invention is a permanent magnet electric motor as described in claim 2. In the permanent magnet electric motor according to the second aspect, the circumferential length D of the void portion and the circumferential length H of the tooth tip portions are configured to satisfy [D ≧ H]. Thereby, the amount of magnetic flux short circuit at the end of the permanent magnet can be further reduced and the effective magnetic flux layer can be further increased, so that the efficiency is further improved. In addition, the present invention
3 invention is a permanent magnet electric motor as described in claim 3.
It is a machine. In the permanent magnet electric motor according to claim 3, rotation is
A cavity is formed by the recess formed on the outer peripheral portion of the child.
Thereby, the rotor can be easily configured. The permanent magnet motor can be downsized by setting the outer diameter of the stator to 90 mm. Further, by using the permanent magnet electric motor of the present invention as a compressor driving electric motor of an air conditioner, a refrigerator, or the like, or as a driving electric motor of an in-vehicle device, each device can be downsized.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. The schematic structure of the permanent magnet motor of the present invention is shown in FIGS. 1 is a sectional view and FIG. 2 is a partially enlarged view of FIG. The permanent magnet electric motor of the present invention includes a rotor 10 and a stator 30. The rotor 10 has a rotor core 11. The rotor core 11 is formed into a substantially cylindrical shape by stacking steel plates such as electromagnetic steel plates. The stator 30 has a stator core (yoke portion) 31. The stator core 11 is, for example,
It is formed into a substantially cylindrical shape by laminating steel plates such as electromagnetic steel plates.

The rotor core 11 is provided at its center with a shaft hole 12 for inserting a rotary shaft. Moreover, a plurality of magnet housing holes for housing (embedding) the permanent magnets are provided in parallel with the shaft hole 12. The magnet housing hole is provided for each magnetic pole. In this embodiment, it is 4 at 90 degree intervals.
The magnet housing holes 21a to 21d are provided in the axial direction. Since the magnet housing holes 21a to 21d have the same structure, the magnet housing hole 21a will be described. The element codes of the magnet housing holes 21b to 21d are used by replacing the alphabets a of the element codes of the corresponding elements of the magnet housing hole 21a with b to d. The magnet accommodating hole 21a is provided in the rotor core 1
1 is a straight inner wall 22 provided on the radial center side.
a, a linear outer wall 23a provided on the outer peripheral side of the rotor core 11 in the radial direction, and extends substantially parallel to the outer peripheral portion of the rotor core 11 from a position where the outer wall 23a is close to the outer peripheral portion of the rotor core 11. (Substantially the same shape) The end walls 24a, 25a, the end wall 24a and the inner wall 22a, the passage wall 2 extending between the end wall 25a and the inner wall 22a, and determining the width of the magnetic flux passage between the magnetic poles.
It is formed by 6a and 27a. The passage wall 26
a and 27a may be omitted. Magnet housing hole 21a
A space is provided between the end walls 24 a and 25 a of the rotor and the outer peripheral portion of the rotor core 11. In the present embodiment, the concave portion (cutout portion) 14a provided on the outer peripheral portion of the rotor core 11,
16a is used as the void. The recess 14a is formed by side walls 14a1 and 14a3 and a bottom wall 14a2. The recess 16a has the same shape. In the present embodiment, the bottom walls 14a2, 16a2 of the recesses 14a, 16a and the end wall 24a and the end wall 25a are provided substantially in parallel (having substantially the same shape). That is, the recess 14a
14d and 16a to 16d are formed such that the radial lengths (depths) at the respective positions along the circumferential direction are substantially equal.

Permanent magnets 20a to 20d each having a substantially rectangular cross-section perpendicular to the axial direction are housed (embedded) in the magnet housing holes 21a to 21d.
Here, permanent magnets of different polarities are housed in the magnet housing holes of the adjacent magnetic poles. For example, the N pole permanent magnet 20a is housed in the magnet housing hole 21a (the outer wall 23a side has N
The pole, the inner wall 22a side is the S pole) and the S pole permanent magnet 20b is housed in the magnet housing hole 21b (the outer wall 23b side is the S pole,
The inner wall 22b side is the N pole). In the present embodiment, since the permanent magnets 20a to 20d each having a substantially rectangular cross section perpendicular to the axial direction are used, the magnet housing hole 2 is used.
Gaps 28a to 28d and 29a to 29d are provided at both ends on the outer peripheral side of the rotor cores 1a to 21d. The gaps 28a to 28d and 29a to 29d may be voids or may be filled with a non-magnetic insulator such as resin. Permanent magnets 20a to 20d are provided 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 part (bridge part) 17a for holding in 1d
17d and 18a-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 each magnetic pole. Further, inter-pole portions 13a to 13d are formed between the recesses 14a to 14d and 16a to 16d of the adjacent magnetic poles.

The stator core 31 has a plurality of teeth portions (magnetic pole portions) 32 protruding in a direction facing the rotor core 11.
a to 32n are provided. Teeth parts 32a to 32
Tip portions (teeth tip portions) 33a to 33n are provided with a gap from the rotor core 11 at a portion facing the rotor core 11 of n. In the slots 34a to 34n formed by the tooth portions 32a to 32n, stator windings are arranged, for example, in a distributed winding method. In addition, the stator core 31 is provided with a passage through which a refrigerant gas and the like penetrate in the axial direction. In FIG. 1, the cutout portions 35a to 35n formed by cutting out the outer peripheral portion of the stator core 31 are used as the passages. The holes can also be used as passages.

Next, the configuration of the first embodiment of the present invention will be specifically described. Now, consider the permanent magnet embedded motor shown in FIGS. In the permanent magnet embedded motor shown in FIGS. 3 and 4, the rotor core 211 of the rotor 210 is
Magnet housing hole 2 for housing the permanent magnets 220a to 220d
21a to 221d are provided for each magnetic pole (FIG. 3,
In FIG. 4, every 90 degrees). Further, the stator core 231 of the stator 230 is provided with teeth portions 232a to 232n forming slots 234a to 234n. The tooth portions 232a to 232n are opposed to the rotor core 211 with a gap therebetween, and the tooth tip portions 233a to 233 are arranged to face each other.
33n are provided. Here, the gap between the magnet housing holes of the adjacent magnetic poles (for example, the magnet housing holes 221a and 221b).
And the adjacent tooth portion 232a.
Assuming that the shortest distance between the side surfaces of ~ 232n is A, [B <
Consider the case where the relationship [A] is set.

In this case, the rotor 210 and the stator 230 are in the positional relationship shown in FIG. 3 (the portion between the magnet accommodating holes 221a and 221b of the adjacent magnetic poles (interpolar magnetic pole passage portion)).
Is opposed to the tooth portion 232a), the magnetic flux φ1 is generated through the central portion of the tooth tip portion 233a in the magnetic pole passage portion between the magnet housing holes 221a and 221b.
Flows. 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 accommodating holes 221a and 221b of the adjacent magnetic poles (interpolar magnetic pole passage portion) is located between the teeth portions 232a and 232b). (Opposite the position), the magnet housing holes 221a and 221a
21b, a tooth tip portion 2
Magnetic flux φ2 through the end of 33a and the tooth tip 23
A magnetic flux φ3 flows through the end of 3b. Here, since the cross-sectional area of the end portions of the tooth tip portions 233a to 233n is small, only a small amount of magnetic flux flows and the tooth tip portions 233a.
~ 233n is magnetically saturated, and it becomes difficult for magnetic flux to flow. Therefore, the sum of the magnetic fluxes φ2 and φ3 is smaller than that of the magnetic flux φ1 and the reluctance torque generated is also small. As described above, when the reluctance torque increases or decreases (changes), the torque pulsation increases, and the vibration and noise caused by the 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 (interval between magnetic poles 13a to 13d). 13n in the circumferential direction) B and the shortest distance A between the side surfaces of the adjacent tooth portions 32a to 32n are [B ≧
A] is satisfied. In this case, when the rotor 10 and the stator 30 are in the positional relationship shown in FIG. 5 (the magnetic pole interspace portion 13a faces the tooth portion 32a), the space between the magnet housing holes 21a and 21b of the adjacent magnetic poles is increased. The magnetic flux φ4 flows through the central portion of the tooth tip end portion 33a in the inter-magnetic pole passage portion. 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 magnetic pole gap portion 13a corresponds to the intermediate portion between the teeth portions 32a and 32b), the magnetic pole gap portion 13a moves toward the teeth tip portion 33a. It also faces the center of the tooth tip 33b. Therefore, in the inter-pole passage portion between the magnet housing holes 21a and 21b of the adjacent magnetic poles, the tooth tip portion 3 is formed.
The magnetic flux φ5 flows through the central portion of 3a (without passing through the end portions of the tooth tip portions 33a) and the magnetic flux φ6 through the central portion of the tooth tip portions 33b (without passing through the end portion of the tooth tip portions 33b). Since the magnetic fluxes φ5 and φ6 flow without passing through the ends of the tooth tips 33a and 33b, the sum of the magnetic fluxes φ5 and φ6 is large, and the reluctance torque generated is also large.

As described above, in the first embodiment, the distance B between the recesses (voids) provided in the adjacent magnetic poles (the length between the magnetic poles) B and the shortest distance between the side surfaces of the adjacent teeth portions. The distance A is configured to satisfy [B ≧ A]. As a result, a large reluctance torque can always be generated regardless of the position of the rotor, which improves efficiency. Further, since the fluctuation of the reluctance torque is reduced, the torque pulsation can be reduced, and the vibration and noise generated due to the torque pulsation can be reduced.

Further, the magnet accommodating holes 221a-22 of each magnetic pole are provided.
When no space is provided between 1d and the outer peripheral portion of the rotor core 211, the magnet housing holes 221a to 221 are provided.
The permanent magnets 220a to 220d housed in d and the teeth tip portions 233 provided on the stator core 231.
A path through which the short-circuit magnetic flux flows may be formed between a and 233n. For example, as shown in FIG. 7, from the N pole of the permanent magnet 220a housed in the magnet housing hole 221a, the permanent magnet 220a is inserted through the tooth tip 233a.
Short-circuit magnetic flux φ7 flows to the S pole. Magnet housing hole 221a-
The permanent magnets 220a-220d accommodated in 221d.
When the short-circuit magnetic flux flows between the tooth tips 233a to 233n, the effective magnetic flux amount decreases. Therefore, the torque is reduced and the efficiency is reduced.

On the other hand, in this embodiment, as shown in FIG. 8, the end walls 24a to 24a of the magnet housing holes 21a to 21d.
Recesses 14a to 14d and 16a to 16d are provided as voids between 24d and 25a to 25d and the outer peripheral portion of the rotor core 11. Further, in the present embodiment, the recess 1
When D is the length of 4a to 14d and 16a to 16d in the circumferential direction and C is the width (distance between side surfaces) of the teeth portions 32a to 32n, [D ≧ C] is satisfied. Here, in the case of being configured so as to satisfy [D ≧ C], FIG.
As shown in, the short-circuit magnetic flux φ8 may flow through the end of the tooth tip 33a. However, as described above, since the cross-sectional areas of the ends of the teeth tip portions 33a to 33n are small, the teeth tip portions 33a to 33n are magnetically saturated by only a small amount of magnetic flux flowing. Therefore, [D ≧
If it is configured to satisfy C], the amount of short-circuit magnetic flux flowing through the tooth tip portions 33a to 33n can be reduced.

As described above, in the first embodiment, the concave portion is provided as the void portion between the end wall of the magnet accommodating hole and the outer peripheral portion of the rotor core, and the radial direction of the concave portion is further increased. The length D and the width of the teeth (distance between the sides) C is [D
≧ C] is satisfied. This makes it possible to reduce the amount of short-circuit magnetic flux that flows between the N pole and the S pole of the permanent magnet housed in the magnet housing hole via the tooth tips provided on the stator core. The 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. As a result, it is possible to reduce vibration and noise generated due to the magnetic attraction force in the radial direction.

In the first embodiment, the circumferential length D of the concave portion and the width (distance between the side surfaces) C of the tooth portion are [D ≧.
By configuring so as to satisfy C], the short-circuit magnetic flux amount of the permanent magnet is reduced, but the short-circuit magnetic flux amount can be further reduced. FIG. 9 shows the configuration of the second embodiment capable of further reducing the short-circuit magnetic flux amount of the permanent magnet.
The basic configuration of the second embodiment is similar to that shown in FIGS. 1 and 2, so only the configuration different from that of the first embodiment will be described. In the present embodiment, the end walls 24a to 24d and 25a to 2 of the magnet housing holes 21a to 21d.
5d and the outer peripheral portion of the rotor core 11 are provided with recesses 14a to 14d and 16a to 16d provided with a circumferential length D, and the teeth tip portions 33a to 33n provided with a circumferential length (rotor core). When the length of 11 in the moving direction) is H, [D ≧
H] is satisfied. In this case,
The short-circuit magnetic flux flowing through the end portions of the tooth tip portions 33a can be reduced more 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 void portion within a predetermined range is used. Here, as shown in FIG. 12, the gap (air gap) between the outer peripheral portion of the rotor core 11 and the tooth tip portion 33a is g, and the concave portions 14a to 14d are formed.
The length (depth) in the radial direction of or 16a to 16d is L. The radial lengths (depths) of the recesses 14a to 14d and 16a to 16d are indicated by, for example, the distance between the magnetic pole inter-part 13a or the effective magnetic pole part 15a and the bottom wall 14a2 of the recess 14a (FIG. 2). When the radial length (depth) of the void is not equal at each position in the circumferential direction (for example, the void shown in FIGS. 20 to 23), the radial length (depth) of the void is large. The shortest length (length of the shallowest portion) of the length) is defined as the length (depth) L of the void.

Usually, when an electric motor is incorporated in a compressor or the like, the rotor 10 may be mounted with a slight deviation from the center due to an assembly tolerance or the like. When the center of the rotor 10 is displaced and attached, the teeth 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 becomes smaller are attached. , It may be deformed by the magnetic attraction force and generate noise. However, in the present embodiment, the recesses 14a to 14d and 16a to 16d are formed in the outer peripheral portion of the rotor core 11.
Is provided, the magnetic attraction force acting on the teeth portions 32a to 32n can be reduced. Thereby, noise generated due to the deformation of the teeth portions 32a to 32n due to the magnetic attraction force can be reduced. Recesses 14a to 14d and 16a formed on the outer peripheral portion of the rotor 10.
The ratio (L / g) of the radial length (depth) L of ˜16d to the gap (air gap) g between the outer peripheral portion of the rotor 10 and the tooth tips 32a to 32n and the noise. The relationship is shown in FIG. It can be seen from FIG. 10 that the generated noise is reduced by setting (L / g) to 0.2 or more.

The recesses 14a to 14d, 16a to 16
The radial length (depth) L of d and the air gap g are
When the relationship of [(L / g) <0.2] is satisfied, the above [D
Even if the relationship of ≧ C] or [D ≧ H] is satisfied, as shown in FIG.
Short-circuit magnetic flux may flow through the central portion and the end portion of 3n. From the N pole of the permanent magnets 20a to 20d housed in the magnet housing holes 21a to 21d, the teeth tip portions 33 to 33 are formed.
When the amount of the short-circuit magnetic flux flowing to the S poles of the permanent magnets 20a to 20d via n increases, the effective magnetic flux amount decreases, so that the efficiency decreases. Also in this respect, (L / g) is 0.2
The efficiency can be improved by setting the above.

The electric motor used in the compressor or the like is operated under high pressure. When operating in such an environment, if the radial length of the concave portion provided on the outer peripheral portion of the rotor is long (deep), as shown in FIG. The resistance increases, and the loss in the concave portion increases when the rotor rotates. That is,
Efficiency is reduced. The ratio (L / g) of the radial length (depth) L of the concave portion formed on the outer peripheral portion of the rotor and the gap (air gap) g between the outer peripheral portion of the rotor and the tooth tips. FIG. 11 shows the relationship with the resistance of the heat exchange medium (refrigerant). From FIG. 11, by setting (L / g) to 0.5 or less, the resistance of the heat exchange medium can be suppressed to be small, and the increase in loss in the recesses 14a to 14d and 16a to 16d is suppressed. I understand.

As described above, in the present embodiment, the gap (air gap) g between the outer peripheral portion of the rotor and the teeth tips, the end wall of the magnet housing hole, and the outer peripheral portion of the rotor core. The radial length (depth) L of the concave portion provided between is
It is configured to satisfy [g × 0.2 ≦ L ≦ g × 0.5]. As a result, the amount of short-circuit magnetic flux passing through the tooth tip portions can be reduced, and the efficiency can be improved. Further, since the loss due to the resistance of the concave portion with respect to the heat exchange medium can be reduced, the efficiency can be improved. Further, since the radial magnetic attraction force acting between the stator and the rotor can be reduced, the noise caused by the magnetic attraction force acting between the stator and the rotor can be reduced. it can.

In the third embodiment, the concave portion formed on the outer peripheral portion of the rotor is used as the space provided between the end wall of the magnet housing hole and the outer peripheral portion of the rotor core. However, other than this, 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 of [L ≦ g × 0.5] described above does not apply. The maximum allowable 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 that house the permanent magnets necessary to obtain the predetermined characteristics, and the like. It

Next, a fourth embodiment will be described. The fourth embodiment uses a method of improving the 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 opening 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 central portion P of the rotor core and both ends of each effective magnetic pole portion as shown in FIG. And In the present embodiment, each of the effective magnetic pole portions 15a-15
The open angle θ of the effective magnetic pole portions 15a to 15d is represented by the relationship between the open angle θ of d and the teeth portions 32a to 32n.
The open angle θ of each of the effective magnetic pole portions 15a to 15d and the tooth portion 32.
The relationship with a to 32n can be represented by the number of teeth portions 32a to 32n facing the effective magnetic pole portions 15a to 15d. Here, the cross-sectional area of the end portion of the tooth tip is small, and only a small amount of magnetic flux flows to cause magnetic saturation, which makes it difficult for the magnetic flux to pass. Therefore, in the present embodiment, the number of teeth portions facing the effective magnetic pole portion is the center portion of the teeth tip portion (the portion corresponding to the columnar main body portion of the teeth portion).
Is represented by the number of tooth portions facing the effective magnetic pole portion.

14 to 16 show the results of the magnetic flux density, the electromotive force constant, and the efficiency of 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 tooth portions, and three and four tooth portions, 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 four and five tooth portions face each other and five and six tooth portions face each other. For example, in pattern C, as the rotor rotates,
The facing state of the effective magnetic pole portion 15a and the tooth portions 32a to 32n sequentially changes as shown in FIGS. 17 (a) to 17 (c). In FIGS. 17A to 17C, the rotor is assumed to rotate clockwise. For example, at any time, FIG.
As shown in (a), four tooth portions 32a to 32d face the effective magnetic pole portion 15a. Next, as shown in FIG. 17B, the five tooth portions 32 are formed on the effective magnetic pole portion 15a.
a to 32e face each other. Next, as shown in FIG. 17C, four tooth portions 32b to 32 are provided on the effective magnetic pole portion 15a.
e faces. In 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.
Shown in. When the number of teeth portions facing the effective magnetic pole portion is small, the tooth magnetic flux density is high and the iron loss is large.
From FIG. 14, patterns C and D have low teeth density,
It can be seen that the iron loss is small. The electromotive force constants for patterns A to D are shown in FIG. The higher the electromotive force constant, the higher the electromotive force, and the higher the amount of magnetic flux in 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. Then, when the electromotive force is high, the drive current becomes small and the copper loss becomes small. From FIG. 15, it can be seen that the electromotive force constants of the patterns A, B, and C in which the magnetic flux that contributes to the electromotive force is concentrated in the teeth portion with a small number are high. The efficiency (motor efficiency) for patterns A to D is shown in FIG.
6 shows. From FIG. 16, it can be seen that the efficiency of the pattern C in which the tooth magnetic flux density is small, the iron loss is small, the electromotive force constant is large, and the copper loss is small is good.

As described above, the open angle θ of the effective magnetic pole portion is set so that four and five tooth portions are alternately opposed to the effective magnetic pole portion, thereby reducing iron loss and copper loss. Therefore, the efficiency can be improved.

Next, a fifth embodiment will be described. Fifth
In the embodiment, the method of improving the efficiency by setting the size of the stator core 31 within a predetermined range is used. As a method of determining the size of the stator core 31, for example, the area of a cross section (stator core cross-sectional area) perpendicular to the axial direction of the stator core 31 shown in FIG. 1 and the stator core 31 are provided. The ratio of the total slot cross-sectional area to the sum of the total area (slot total cross-sectional area) of the cross sections of the slots 34a to 34n formed by the tooth portions 32a to 32n perpendicular to the axial direction is used. Stator core 31 shown in FIG.
In the above shape, the sum of the stator core cross-sectional area and the total slot cross-sectional area is [(Ra / 2) ² π-{(Rb / 2) ² π + G}]
It is represented by. Here, Ra is the outer diameter of the stator core 31, R
“B” represents the inner diameter of the stator core 31, and “G” represents the total area of the cross sections of the notches 35a to 35n (passages) provided in the stator core 31 perpendicular to the axial direction. The total slot cross-sectional area is shown by [S × z]. Where S is slot 3
Areas of cross sections 4a to 34n perpendicular to the axial direction, and z represents the number of slots. Then, the total slot cross-sectional area [S × z] is
Sum of stator core cross-sectional area and total slot cross-sectional area [(Ra /
2) The efficiency in the case of multiplying ² π-{(Rb / 2) ² π + G}] by various coefficients (ratio) is obtained, and the range of the coefficient that can improve the efficiency is determined.

Stator outer diameter Ra is 90 mm, stator inner diameter R
b is 51 mm and the total cross-sectional area G of the cutouts 35a to 35n is 2
The table of FIG. 19 shows the results of copper loss, iron loss, efficiency, etc. when the slot cross-sectional area S was changed by changing the coefficient with 75.4 mm ² and the number of slots n being 24. The values shown in FIG. 19 are obtained under the condition of the same input power, the same rotation speed, and the same torque. In addition, FIG.
9 is a graph showing the relationship between copper loss, iron loss, and efficiency with respect to the slot cross-sectional area S shown in FIG. 18,
From FIG. 19, the slot cross-sectional area S is small (coefficient is 0.2
It is found that the wire loss of the stator windings arranged in the slots 34a to 34n is too small and the copper loss is large. Further, when the slot cross-sectional area S is large (coefficient is larger than 0.4), the current increases to cover the efficiency decrease due to the magnetic saturation of the stator core 31,
It can be seen that the copper loss is large. From the above, the total slot cross-sectional area [S / z] 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] is satisfied, copper loss and iron loss can be reduced and efficiency can be improved. This embodiment can also be applied to the case where the holes formed in the stator core are used as the passages.

In the above embodiment, the recesses having the same radial length (depth) are provided between the end wall of the magnet accommodating hole and the outer peripheral portion of the rotor core as a space. Department is
It may be a hole provided between the end wall of the magnet housing hole and the outer peripheral portion of the rotor core. Further, the shapes and numbers of the recesses and holes provided between the end wall of the magnet housing hole and the outer peripheral portion of the rotor core can be variously changed. Further, the shape of the magnet housing hole provided in the rotor core and the shape of the permanent magnet housed in the magnet housing hole can be variously changed. 20 to 23 show another embodiment of the rotor. 20 to 23A show a rotor having a recess between the end wall of the magnet housing hole and the outer peripheral portion of the rotor core, and FIGS. 20 to 23B show the magnet. The rotor which provided the hole between the end 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. In the rotor shown in FIG. 20A, the magnetic poles of the rotor core 40 have a central portion 43a, outer peripheral portions 42a and 44, respectively.
A magnet accommodating hole 41a having a sectional shape perpendicular to the axial direction and having a trapezoidal shape with the convex side facing the center is formed. Further, recesses 45a and 46a are formed between the end wall of the magnet housing hole 41a and the outer peripheral portion of the rotor core 40. The side walls of the recesses 45a and 46a are formed parallel to the outer walls (or inner walls) of the outer peripheral portions 42a and 44a of the magnet housing hole 41a. Then, the magnet housing hole 41
Permanent magnets 47a, 48a, 49a having a substantially rectangular cross-section perpendicular to the axial direction are housed in the central portion 43a and the outer peripheral portions 42a and 44a of a. Figure 20
The rotor shown in (b) has a magnet accommodating hole 5 in each magnetic pole of the rotor core 50, similar to the rotor core 40 shown in FIG. 20 (a).
1a and permanent magnets 57a to 59a, and magnet housing hole 51
A hole 55a is formed between the outer peripheral portion of the rotor core 50 and the outer peripheral portions 52a and 54a of the rotor core 50 on the outer peripheral portion side of the rotor core 50.
And 56a are formed.

In the rotor shown in FIG. 21 (a), each magnetic pole of the rotor core 60 has a central portion such that the cross-section of the rotor core 60 at right angles to the axial direction has a C-shape with the convex side facing the center. 62
First and second magnet housing holes 61a and 63a are formed on both sides of a. In addition, the first and second magnet housing holes 61a
And 63a are formed between the end wall on the outer peripheral side of the rotor core 60 and the outer peripheral portion of the rotor core 60. First and second magnet housing holes 61a and 63
The end wall on the side of the central portion 62a of a is formed substantially in parallel. Then, the first and second magnet housing holes 61a and 63a
Accommodates permanent magnets 66a and 67a having a substantially rectangular cross-section perpendicular to the axial direction. Figure 21
The rotor shown in (b) has the same first and second magnetic poles of the rotor core 70 as the rotor core 60 shown in FIG.
Magnet housing holes 71a and 73a, permanent magnets 76a and 77
a, and holes 74a and 75a are formed between the end wall of the first and second magnet housing holes 71a and 73a on the outer peripheral side of the rotor core 70 and the outer peripheral portion of the rotor core 70. .

In the rotor shown in FIG. 22A, the magnetic poles of the rotor core 80 have first and second accommodating portions 82a and 83a.
And a magnet housing hole 81a having a cross section perpendicular to the axial direction and having a C-shape with the convex side facing the center side is formed. Further, recesses 84a and 85a are formed between the end wall of the magnet housing hole 81a and the outer peripheral portion of the rotor core 80. First and second housing portions 82a of the magnet housing hole 81a
And 83a house permanent magnets 86a and 87a having a substantially rectangular cross-section perpendicular to the axial direction. The rotor shown in FIG. 22 (b) has magnet housing holes 91 a, permanent magnets 96 a and 97 a similar to those of the rotor core 70 shown in FIG. 22 (a) in each magnetic pole of the rotor core 90. Holes 94a and 95a are formed between the end wall of the hole 91a and the outer peripheral portion of the rotor core 90.

In the rotor shown in FIG. 23 (a), each magnetic pole of the rotor core 100 has a magnet accommodating hole 101a having a cross-sectional shape perpendicular to the axial direction and having an arcuate shape with the convex side facing the center side.
Are formed. Further, recesses 102a and 103a are formed between the end wall of the magnet housing hole 101a and the outer peripheral portion of the rotor core 100. In the magnet housing hole 101a,
Permanent magnet 1 having a circular arc-shaped cross section perpendicular to the axial direction
04a is accommodated. The rotor shown in FIG. 23 (b) has a magnet housing hole 111a and a permanent magnet 114a similar to those of the rotor core 100 shown in FIG. 23 (a) in each magnetic pole of the rotor core 110, and the magnet housing hole 111a. Holes 112a and 113a between the end wall of the rotor and the outer periphery of the rotor core 110.
Are formed.

The present invention is not limited to the configurations described in the embodiments, and various changes, additions and deletions can be made. For example, although each magnetic pole of the rotor is formed of a single layer, each magnetic pole may be formed of multiple layers. Further, the shape of the magnet housing hole and the shape of the permanent magnet can be variously changed. Further, the material of the permanent magnet can be variously changed. Further, the sizes of the stator and the rotor can be variously changed. Moreover, although the case of using it for the compressor has been described, the permanent magnet motor of the present invention is
It can be used as an electric motor of various devices such as a refrigerator and an in-vehicle device driven by an electric motor.

[0035]

As described above, claims 1 to 1
If the permanent magnet electric motor described in 7 is used, it is possible to reduce the size while maintaining a predetermined performance even when a PWM control type inverter is used as a power supply source.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a schematic configuration of a permanent magnet electric motor of the present invention.

FIG. 2 is a partially enlarged view of FIG.

FIG. 3 is a diagram illustrating the configuration and operation of the first embodiment of the present invention.

FIG. 4 is a diagram illustrating the configuration and operation of the first embodiment of the present invention.

FIG. 5 is a diagram illustrating the configuration and operation of the first embodiment of the present invention.

FIG. 6 is a diagram illustrating the configuration and operation of the first embodiment of the present invention.

FIG. 7 is a diagram illustrating the configuration and operation of the first embodiment of the present invention.

FIG. 8 is a diagram illustrating the configuration and operation of the first embodiment of the present invention.

FIG. 9 is a diagram illustrating the configuration and operation of the second embodiment of the present invention.

FIG. 10 is a diagram illustrating an effect of the third embodiment of the present invention.

FIG. 11 is a diagram illustrating an effect of the third embodiment of the present invention.

FIG. 12 is a diagram illustrating the configuration and operation of the third embodiment of the present invention.

FIG. 13 is a diagram illustrating the configuration and operation of the third embodiment of the present invention.

FIG. 14 is a diagram illustrating an effect of the fourth embodiment of the present invention.

FIG. 15 is a diagram illustrating effects of the fourth embodiment of the present invention.

FIG. 16 is a diagram illustrating an effect of the fourth embodiment of the present invention.

FIG. 17 is a diagram illustrating the configuration and operation of the fourth embodiment of the present invention.

FIG. 18 is a diagram illustrating an effect of the fifth embodiment of the present invention.

FIG. 19 is a diagram for explaining effects of the fifth embodiment of the present invention.

FIG. 20 is a view showing another embodiment of the rotor.

FIG. 21 is a view showing another embodiment of the rotor.

FIG. 22 is a view showing another embodiment of the rotor.

FIG. 23 is a view showing another embodiment of the rotor.

[Explanation of symbols]

10, 210 Rotor 11, 40, 50, 60, 70, 80, 90, 100,
110, 211 rotor cores 14a to 14d, 16a to 16d, 45a, 46a, 6
4a, 65a, 84a, 85a, 102a, 103a
Recesses (voids) 15a to 15d Effective magnetic pole portions 21a to 21d, 41a, 51a, 61a, 63a, 7
1a, 73a, 81a, 91a, 101a, 111a,
221a to 221d Magnet housing holes 20a to 20d, 47a to 49a, 57a to 59a, 6
6a, 67a, 76a, 77a, 86a, 87a, 96
a, 97a, 104a, 114a, 220a to 220d
Permanent magnets 30, 230 Stator 31, 231 Stator cores 32a to 32n, 232a to 232n Teeth portions 33a to 33n, 233a to 233n Teeth tip portions 34a to 34n, 234a to 234n Slots 35a to 35n Notches 55a, 56a, 74a , 75a, 94a, 95a, 1
12a, 113a, holes

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-10-66284 (JP, A) JP-A-2002-171730 (JP, A) JP-A-2002-165394 (JP, A) JP-A-2000-116084 (JP , A) JP 2001-178045 (JP, A) JP 2000-324728 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H02K 1/27 H02K 1/22 H02K 21 / 14

Claims (7)

(57) [Claims] 1. A stator in which a slot for accommodating a stator winding is formed, and a tooth portion having a tooth tip portion including a central portion and an end portion is provided in a portion facing the rotor, and a tooth tip. And a rotor having a magnet accommodating hole for accommodating a permanent magnet in each magnetic pole, which is disposed with a gap between the magnet and the end, the end wall of the magnet accommodating hole and the outer peripheral portion of the rotor. A gap is provided between the adjacent magnetic poles, B is the distance between the adjacent magnetic poles, A is the shortest distance between the side surfaces of the adjacent teeth, C is the width of the teeth, and When the length in the circumferential direction is D, B ≧ A and D ≧ C are satisfied, and a gap between the outer peripheral portion of the rotor and the tip of the teeth is g.
The shortest radial length at each position in the circumferential direction of the gap
When was the L, g × 0.2 ≦ L ≦ g × 0.5 is configured to satisfy the permanent magnet motor. 2. The permanent magnet electric motor according to claim 1, wherein D ≧ H is satisfied when the circumferential length of the tooth tip portion is H. 3. The permanent magnet electric motor according to claim 1 or 2 , wherein the void portion provided between the end wall of the magnet housing hole and the outer peripheral portion of the rotor is the outer peripheral portion of the rotor. A permanent magnet electric motor, which is a recess formed in the. 4. The permanent magnet electric motor according to claim 1 , wherein the stator has an outer diameter of 90 mm. 5. An air conditioner for adjusting the temperature in a room using a heat exchange medium compressed by a compressor, wherein the permanent magnet electric motor according to claim 1 is used as a driving motor for the compressor. There was an air conditioner. 6. A refrigerator in which the temperature inside the refrigerator is adjusted by using a heat exchange medium compressed by a compressor, wherein the permanent magnet electric motor according to any one of claims 1 to 4 is used as a drive motor for the compressor. I had a refrigerator. 7. An in-vehicle device driven by an electric motor, the in-vehicle device using the permanent magnet electric motor according to claim 1 as an electric motor.