JP5511921B2 - Electric motor, blower and compressor - Google Patents

Description

  The present invention relates to an electric motor. Specifically, the present invention relates to the shape of the permanent magnet end gap and slit of the rotor of the embedded permanent magnet electric motor and the stator. Moreover, it is related with the air blower and compressor which use the electric motor.

  In general, the torque ripple at the low speed of a brushless DC motor is dominated by cogging torque caused by field magnetic flux generated by a magnet provided in the rotor.

  The cogging torque has a fundamental wave component that varies with the least common multiple of the number of poles of the rotor and the number of slots of the stator per rotation of the rotor of the brushless DC motor. The cogging torque also has higher frequency components.

  Conventionally, a technique for reducing cogging torque has been proposed by setting a predetermined angle to the circumferential direction of the tip of the air gap extending toward the center of the field magnet of the rotor (for example, Patent Documents). 1).

JP 2008-61444 A International Publication No. 2008/105049 JP 11-46464 A US Pat. No. 6,717,314 JP 2004-180460 A JP 2002-369482 A JP 2004-236431-A

  The cogging torque is generated from the shape of the rotor and the shape of the stator. In the shape of the rotor described in Patent Document 1, the relationship with the shape of the stator is not shown. The proper shape of the rotor when changed was not shown.

  The present invention has been made in order to solve the above-described problems. An electric motor capable of reducing the cogging torque by clarifying the relationship between the stator shape and the rotor shape, and the blower and the compression using the electric motor. Provide a machine.

The electric motor according to this invention is
A stator core having a plurality of teeth that are configured by laminating a predetermined number of electromagnetic steel sheets punched into a predetermined shape and extending radially at equal intervals from the outer core back, and
A rotor core that is arranged inside the stator core and is formed by laminating a predetermined number of electromagnetic steel sheets punched into a predetermined shape, and a plurality of magnet insertion holes are formed in the circumferential direction along the outer peripheral edge. Rotor core,
8 or more permanent magnets inserted one by one in each magnet insertion hole,
On the outside of each magnet insertion hole, a gap extending in the circumferential direction from the circumferential end of each magnet insertion hole toward the pole center is provided,
The angle formed by two straight lines connecting the ends of two gaps adjacent to each other between the two magnet insertion holes adjacent to each other between the poles and the center of the rotor core is θ1, and each tooth When the angle formed by two straight lines connecting the circumferential tip of both ends of the core and the center point of the stator core is θ4,
θ4 <θ1
Satisfy the relationship
The number of teeth of the stator core is the number of poles × 3.

  The electric motor according to the present invention is an angle formed by two straight lines connecting the pole center side ends of the two gaps adjacent to each other between the two magnet insertion holes adjacent to each other between the poles and the center of the rotor core. Is θ1, and the angle formed by two straight lines connecting the circumferential tip 12b at both ends of the tooth 12 and the center point of the stator core 11 (which coincides with the center of the rotor core 21) is θ4 <θ1 By satisfying this relationship, the magnetic flux generated from the permanent magnet has an effect of preventing leakage magnetic flux entering the adjacent permanent magnet from the tip of the stator teeth. As a result, the magnetic flux that can be effectively used is increased, the induced voltage is improved, and the torque can be improved.

FIG. 3 shows the first embodiment and is a cross-sectional view of the electric motor 100. FIG. 5 shows the first embodiment, and is a cross-sectional view of the stator 10. The elements on larger scale of FIG. FIG. 3 shows the first embodiment, and is a cross-sectional view of the rotor 20. The elements on larger scale of FIG. The elements on larger scale which omitted the permanent magnet 22 from FIG. FIG. 5 shows the first embodiment, and is a cross-sectional view of the electric motor 100 in which angles of respective parts are defined. Fig. 5 shows the first embodiment, and is a cross-sectional view of a modified example of the electric motor 200. Fig. 5 shows the first embodiment, and is a cross-sectional view of a rotor 30 of a motor 200 according to a modification. The elements on larger scale of FIG. The elements on larger scale which omitted the permanent magnet 22 from FIG. It is a figure shown for a comparison and the cross-sectional view of the electric motor 300 without a space | gap. It is a figure shown for a comparison and is a cross-sectional view of the rotor 40 of the electric motor 300 without a gap. The elements on larger scale of FIG. The elements on larger scale which omitted the permanent magnet 22 from FIG.

Embodiment 1 FIG.
1 to 11 show the first embodiment. FIG. 1 is a transverse sectional view of the electric motor 100, FIG. 2 is a transverse sectional view of the stator 10, FIG. 3 is a partially enlarged view of FIG. FIG. 5 is a partially enlarged view of FIG. 4, FIG. 6 is a partially enlarged view of the rotor 20 with the permanent magnets 22 omitted, and FIG. 7 is a transverse sectional view of the electric motor 100 in which the angles of the respective parts are defined. 8 is a cross-sectional view of a modified electric motor 200, FIG. 9 is a cross-sectional view of a rotor 30 of the modified electric motor 200, FIG. 10 is a partially enlarged view of FIG. 9, and FIG. FIG.

  12 to 15 are diagrams for comparison, FIG. 12 is a cross-sectional view of the motor 300 without a gap, FIG. 13 is a cross-sectional view of the rotor 40 of the motor 300 without a gap, and FIG. FIG. 15 is a partially enlarged view in which the permanent magnet 22 is omitted from FIG.

  With reference to FIG. 1, the configuration of the electric motor 100 will be described taking a permanent magnet embedded electric motor as an example.

  The electric motor 100 includes a stator 10 and a rotor 20.

  The configuration of the stator 10 will be described with reference to FIG. The stator 10 includes at least a stator core 11 and a stator winding (not shown).

  The stator core 11 is configured by punching thin electromagnetic steel sheets having a thickness of about 0.1 to 1.0 mm into a predetermined shape one by one and laminating a predetermined number.

  The stator core 11 has a substantially thick cylindrical shape. A ring-shaped core back 14 is provided on the outer periphery, and teeth 12 extend radially inward from the core back 14 at substantially equal intervals in the circumferential direction. The width (circumferential direction) of the teeth 12 is substantially the same. Here, an example of 12 teeth 12 is shown. However, the number of teeth 12 is not limited to twelve.

  Both ends of the tip 12a (rotor 20 side) of the tooth 12 extend in an umbrella shape in the circumferential direction. Both ends in the circumferential direction of the tip 12a of the tooth 12 are referred to as a circumferential tip 12b.

  An angle formed by two straight lines connecting the center point of the stator core 11 and the circumferential tips 12b at both ends of the teeth 12 is defined as θ4.

  A space between the teeth 12 is referred to as a slot 13. The number of slots 13 is twelve, which is the same as the number of teeth 12. Since the width (circumferential direction) of the teeth 12 is substantially equal, the width of the slot 13 gradually increases toward the core back 14.

  A slot opening 15 serving as an opening is provided on the inner diameter of the slot 13. A winding is inserted into the slot 13 from the slot opening 15.

  The slot opening 15 is a portion between the circumferential tips 12b of adjacent teeth 12.

  Usually, a three-phase winding is applied via an insulating member (not shown) in concentrated winding or distributed winding.

  The configuration of the rotor 20 will be described with reference to FIGS. 1 and 4 to 6. The rotor 20 includes at least a rotor core 21 and a permanent magnet 22.

  The rotor 20 is composed of a rotor core 21 having a cylindrical shape and a shaft hole (not shown) in the center, a permanent magnet 22, an end plate (not shown) for preventing the permanent magnet 22 from coming off. End plates are arranged at both axial ends of the rotor core 21 with the permanent magnets 22 inserted therein, and the whole is fixed by, for example, rivets (not shown).

  Similarly to the stator core 11, the rotor core 21 is formed by punching thin electromagnetic steel sheets having a thickness of about 0.1 to 1.0 mm into a predetermined shape one by one and laminating a predetermined number. .

  The rotor 20 is a four-pole one having four permanent magnets 22. The number of permanent magnets 22 (four) is provided with magnet insertion holes 23 (particularly refer to FIG. 6) that are long in the circumferential direction along the outer peripheral edge of the rotor core 21.

  The permanent magnet 22 is a flat plate having a rectangular cross section. The circumferential length of the magnet insertion hole 23 is longer than the circumferential length of the permanent magnet 22. Therefore, when the permanent magnet 22 is inserted into the magnet insertion hole 23, a gap remains on both sides of the permanent magnet 22 in the circumferential direction. This portion is defined as a leakage flux suppressing hole 23a (see FIG. 6).

  The leakage magnetic flux suppression hole 23a of the magnet insertion hole 23 is provided to suppress the leakage magnetic flux of the permanent magnet 22 between the poles.

  For reference, the permanent magnet 22 is indicated by a broken line in FIG.

The rotor core 21 further includes the following elements.
(1) A gap 24 (long hole shape) extending from the leakage magnetic flux suppression hole 23a of the magnet insertion hole 23 in the circumferential direction toward the pole center outside the magnet insertion hole 23;
(2) A plurality of slits 25 (here, two per pole) formed in a substantially radial direction in the iron core portion outside the permanent magnet 22. The slit 25 is provided symmetrically with respect to the pole center. However, the slit 25 may not be symmetric with respect to the pole center.

  In the example shown in FIGS. 5 and 6, the leakage flux suppressing hole 23 a of the magnet insertion hole 23 is defined as a part of the gap 24 extending in the circumferential direction toward the pole center.

Next, the angle of each part is defined using FIG.
(1) Two connecting the pole center side end portions 24a (see FIG. 6) of the two gaps 24 adjacent to each other between the two adjacent magnet insertion holes 23 with the poles in between, and the center of the rotor core 21. The angle formed by two straight lines is θ1;
(2) In each pole, an angle formed by two straight lines connecting the end 25a on the pole center side of the gap 24 and the outer end 25a on the gap 24 side of the slit 25 adjacent to the center of the rotor core 21. θ2;
(3) An angle formed by two straight lines connecting the circumferential ends of the gap 24 existing at both ends of the magnet insertion hole 23 and the center of the rotor core 21 is θ3;
(4) An angle formed by two straight lines connecting the circumferential tip 12b at both ends of the tooth 12 and the center point of the stator core 11 (coincident with the center of the rotor core 21) is θ4.

  By setting θ4 <θ1 and θ4> θ2, cogging torque can be reduced and induced voltage can be improved. This will be described in detail below.

  A magnetic flux generated from a certain permanent magnet 22 forms a loop that passes through the stator 10 through the adjacent permanent magnet 22 and returns to the permanent magnet 22 that generated the original magnetic flux.

  Further, the effective magnetic flux generated from the permanent magnet 22 is a magnetic flux that is linked to the winding (not shown) through the stator 10, and the magnetic flux that is not linked to the winding of the stator 10 is generated by the motor 100. Does not contribute to torque. That is, in order to use the magnetic flux of the permanent magnet 22 effectively, the rotor 20 shape is required so that the magnetic flux of the permanent magnet 22 is linked to the winding of the stator 10 as much as possible.

  By having a relationship of θ4 <θ1, the magnetic flux generated from the permanent magnet 22 has an effect of preventing leakage magnetic flux entering the adjacent permanent magnet 22 from the tip 12a of the teeth 12 of the stator 10.

  By providing the gap 24 including the leakage magnetic flux suppression hole 23a of the magnet insertion hole 23 and making the relationship θ4 <θ1, the magnetic flux that can be used effectively increases, the induced voltage is improved, and the torque can be improved.

  For comparison, FIGS. 12 to 15 show an electric motor 300 and a rotor 40 that have no gap 24 and have a relationship of θ4 ≧ θ1.

  The electric motor 300 shown in FIG. 12 to FIG. 15 is similar to the electric motor 100 shown in FIG. 1 to FIG. 7 from the leakage magnetic flux suppression hole 23a of the magnet insertion hole 23. )

  The stator 10 of the electric motor 300 is the same as that shown in FIG. 1, but the rotor 40 is different. The rotor 40 does not have the air gap 24 (long hole shape) extending in the circumferential direction from the leakage flux suppressing hole 23a of the magnet insertion hole 23 toward the pole center.

  Θ1 (FIG. 13) in the case of the rotor 40 is the permanent magnet 22 side of the leakage flux suppressing hole 23a of the two magnet insertion holes 23 adjacent to each other of the two magnet insertion holes 23 adjacent to each other with the poles in between. Is an angle formed by two straight lines passing through the outer end 23b (see FIG. 15) and the center of the rotor 40.

  The relationship between the angles θ4 and θ1 formed by two straight lines connecting the circumferential tip 12b at both ends of the tooth 12 and the center point of the stator core 11 (coincident with the center of the rotor core 21) is as follows. In this case, θ4 ≧ θ1.

  Therefore, the magnetic flux generated from the permanent magnet 22 flows as shown by the arrows in FIG. That is, there is a path in which the magnetic flux generated from the permanent magnet 22 enters the tip end portion 12 a of the tooth 12 of the stator 10 and returns to the adjacent permanent magnet 22. Thus, since the rotor 40 does not have the gap 24 (long hole shape) extending in the circumferential direction from the leakage magnetic flux suppression hole 23a of the magnet insertion hole 23 toward the pole center, the tip of the teeth 12 of the stator 10 Since the magnetic flux leaking from the portion 12a to the adjacent permanent magnet 22 increases, the magnetic flux of the permanent magnet 22 cannot be used effectively.

  On the other hand, the electric motor 100 shown in FIGS. 1 to 7 has a gap 24 (long hole shape) in which the rotor 40 extends in the circumferential direction from the leakage flux suppressing hole 23a of the magnet insertion hole 23 toward the pole center. In addition, two straight lines connecting the pole center side end portions 24a (see FIG. 6) of the two gaps 24 adjacent to each other of the two adjacent magnet insertion holes 23 with the poles in between and the center of the rotor core 21. Is θ1, and the angle between two straight lines connecting the circumferential tip 12b at both ends of the tooth 12 and the center point of the stator core 11 (coincident with the center of the rotor core 21) is θ4. By satisfying the relationship of θ4 <θ1, the magnetic flux leaking to the adjacent permanent magnet 22 via the tip 12a of the teeth 12 of the stator 10 is reduced, so that the magnetic flux of the permanent magnet 22 can be used effectively. It becomes.

  Further, an angle θ2 formed by two straight lines connecting the end 25a of the slit 25 adjacent to the pole center side end 24a of the gap 24 and the outer end 25a on the gap 24 side and the center of the rotor core 21, and both ends of the teeth 12 The relationship between the angle θ4 formed by two straight lines connecting the circumferential tip 12b and the center point of the stator core 11 (coincident with the center of the rotor core 21) is θ4> θ2. There is an effect to show.

  That is, the magnetic flux generated from the permanent magnet 22 can be concentrated in a portion smaller than the tip 12a of the tooth 12 of the stator 10.

  Furthermore, since there are a plurality of slits 25, there are a plurality of portions where the magnetic flux generated from the permanent magnet 22 is concentrated. As a result, the number of permanent magnets 22 is virtually increased, and the frequency component of cogging torque can be shifted to higher order.

  Since the frequency component of the cogging torque is shifted to higher order, and the magnetic flux from the permanent magnet 22 is dispersed and concentrated, the pulsation is reduced and the cogging torque can be reduced.

  In the case of the electric motor 100 of FIG. 1, since it has 4 poles and 12 slots, the cogging torque has a dominant 12th order component. However, by setting θ4> θ2, the cogging torque is shifted to the higher order, the 24th order component is increased, and the pulsation is reduced.

  That is, by setting θ4 <θ1 and θ4> θ2, it is possible to increase torque and reduce cogging torque by improving the induced voltage.

  In addition, the configuration of the slits 25 formed in the iron core on the outer peripheral side of the magnet insertion hole 23 is two, and the number of the slits 25 is two. The shape is improved.

  The width between the two slits 25 formed in the iron core on the outer peripheral side of the magnet insertion hole 23 is A, and A is larger than the slot opening 15. Thereby, even when the magnetic pole center coincides with the slot opening 15, the teeth are always present in the width A. Therefore, even when the magnetic pole center coincides with the slot opening 15, the magnetic flux passing between the two slits 25 (width A) from the permanent magnet 22 easily flows to the teeth 12, and the magnetic flux of the permanent magnet 22 is used effectively. Can do.

  Further, when the shape of the slit 25 is oblique with respect to the pole center line, an acute angle portion is formed, so that the punchability of the mold is deteriorated. Therefore, by arranging the two slits 25 substantially perpendicular to the permanent magnet 22, the acute angle portion of the slits 25 is eliminated, and the punchability of the mold is improved.

  Furthermore, by making the angle θ3 formed by two straight lines connecting the circumferential ends of the gap 24 existing at both ends of the magnet insertion hole 23 and the center of the rotor core 21 larger than the slot opening 15, the slot opening 15 Cogging torque pulsation can be suppressed.

  Since the cogging torque is generated due to the presence of the slot opening 15, by making the θ3 portion where the magnetic flux is weaker than the slot opening, the change in the magnetic flux from the θ2 portion to the inter-pole portion changes stepwise, and the magnetic flux suddenly Therefore, the pulsation of the cogging torque due to the slot opening can be suppressed.

  A modified example of the electric motor 200 will be described with reference to FIGS. The stator 10 of the modified example of the electric motor 200 is the same as the electric motor 200 of FIGS. 1 to 7.

  The rotor 30 of the electric motor 200 according to the modified example is different from the rotor 20 of the electric motor 200 shown in FIGS. As shown in FIG. 11, the rotor 30 of the electric motor 200 according to the modification has a gap 24 extending in the circumferential direction from the leakage flux suppressing hole 23 a of the magnet insertion hole 23 toward the pole center, thereby suppressing leakage flux of the magnet insertion hole 23. It is formed separately from the hole 23a.

  By separating the gap 24 and the leakage flux suppressing hole 23a, the thin portion 26 on the outer periphery of the rotor 30 near the gap 24 is divided, and the strength against centrifugal force and the like is improved.

  In order to prevent leakage magnetic flux, the dimension of the thin portion 26 in the radial direction is often configured as thin as possible with sufficient strength. Therefore, by separating the gap 24 and the leakage flux suppressing hole 23a, the thin portion 26 on the outer peripheral portion of the rotor 30 near the gap 24 portion is divided, and the circumferential length of the thin portion 26 is shortened and the strength is improved. In addition, the radial dimension of the thin portion 26 can be further reduced, and the leakage magnetic flux can be reduced.

  The electric motor 100 in FIG. 1 and the electric motor 200 in FIG. 8 have 12 slots and 4 poles, but this embodiment can be applied regardless of the relationship between the slots and the number of poles.

  The most effective effect can be obtained when the number of teeth 12 of the stator 10 is the number of poles × 3 × n (n = 1, 2, 3,... Natural number).

  The example of 12 slots and 4 poles shown in this embodiment is when n = 1.

  When the number of teeth 12 of the stator 10 is the number of poles × 3 × n (n = 1, 2, 3,... Natural number), the distance between the poles of the rotors 20 and 30 is the teeth 12 of the stator 10. When facing each other, all the poles face the teeth 12. Therefore, the two pole connecting portions 24a (see FIG. 6) of the two gaps 24 adjacent to each other between the two adjacent magnet insertion holes 23 with the poles in between are connected to the center of the rotor core 21. When the angle formed by the straight line is θ1, and the angle formed by the two straight lines connecting the circumferential tip 12b at both ends of the tooth 12 and the center point of the stator core 11 (coincident with the center of the rotor core 21) is θ4. , Θ4 <θ1 has an effect of preventing leakage magnetic flux that enters the adjacent permanent magnet 22 from the tip 12a of the teeth 12 of the stator 10 with respect to the magnetic flux generated from the permanent magnet 22.

  In the electric motors 100 and 200 of the present embodiment, the cogging torque is reduced and the vibration can be reduced, so that the secular change is small and the life can be extended.

  Further, by mounting the electric motor in Embodiment 1 on a compressor such as a refrigeration cycle apparatus or a blower such as an air conditioner, a highly efficient, low-cost, long-life compressor and blower can be obtained.

  10 Stator, 11 Stator Core, 12 Teeth, 12a Tip, 12b Circumferential Tip, 13 Slot, 14 Core Back, 15 Slot Opening, 20 Rotor, 21 Rotor Core, 22 Permanent Magnet, 23 Magnet Insertion Hole , 23a Leakage magnetic flux suppression hole, 23b end, 24 gap, 24a pole center side end, 25 slit, 25a end, 26 thin part, 30 rotor, 40 rotor, 100 electric motor, 200 electric motor, 300 electric motor.

Claims (11)

A stator core having a plurality of teeth that are configured by laminating a predetermined number of electromagnetic steel sheets punched into a predetermined shape and extending radially at equal intervals from the outer core back, and
A rotor core that is arranged inside the stator core and is formed by laminating a predetermined number of electromagnetic steel sheets punched into a predetermined shape, and a plurality of magnet insertion holes are formed in the circumferential direction along the outer peripheral edge. Rotor core,
8 or more permanent magnets inserted one by one in each magnet insertion hole,
On the outside of each magnet insertion hole, a gap extending in the circumferential direction from the circumferential end of each magnet insertion hole toward the pole center is provided,
The angle formed by two straight lines connecting the ends of two gaps adjacent to each other between the two magnet insertion holes adjacent to each other between the poles and the center of the rotor core is θ1, and each tooth When the angle formed by two straight lines connecting the circumferential tip of both ends of the core and the center point of the stator core is θ4,
θ4 <θ1
Satisfy the relationship
The number of teeth of the stator iron core is the number of poles × 3. The number of permanent magnets provided in the electric motor is eight,
The electric motor according to claim 1, wherein the number of teeth of the stator core is 24. The number of permanent magnets provided in the electric motor is 10,
The electric motor according to claim 1, wherein the number of teeth of the stator core is 30. A plurality of slits formed in a substantially radial direction are formed in the outer core portion of each permanent magnet,
When the angle formed by two straight lines connecting the end of each magnet insertion hole on the pole center side of each gap and the outer end of each slit near the gap on the gap side and the center of the rotor core is θ2. ,
θ4> θ2
The electric motor according to claim 1, wherein the relationship is satisfied.   The electric motor according to claim 4, wherein the number of slits formed in the outer core portion of each permanent magnet is two.   6. The electric motor according to claim 4, wherein a slit formed in an iron core portion outside each permanent magnet extends substantially perpendicularly to each permanent magnet.   The electric motor according to claim 1, wherein each gap of each magnet insertion hole is separated from each magnet insertion hole. The stator iron core is provided with a slot opening formed between the teeth, and a slot opening that opens to the inner periphery of each slot facing the rotor iron core.
6. The electric motor according to claim 5, wherein A is larger than each slot opening, where A is the width between the slits formed in the outer core portion of each permanent magnet.   9. The electric motor according to claim 8, wherein an angle θ3 formed by two straight lines connecting the circumferential ends of each gap of each magnet insertion hole and the center of the rotor core is larger than each slot opening.   A blower comprising the electric motor according to any one of claims 1 to 9.   A compressor comprising the electric motor according to any one of claims 1 to 9.

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