Motor and compressor

Abstract

The utility model discloses a motor and a compressor, the compressor comprises the motor, and the motor comprises a rotor, a permanent magnet and a stator. The rotor is provided with a plurality of magnet grooves which are arranged at intervals in the circumferential direction of the rotor, the magnet grooves are arranged in a penetrating mode in the axis direction of the rotor, and in a section obtained by sectioning the rotor in the direction perpendicular to the axis of the rotor, each magnet groove comprises a first linear segment, a second linear segment and a third linear segment, and the midperpendicular of each first linear segment passes through the axis of the rotor; the second linear section and the third linear section are symmetrically arranged at the two ends of the first linear section, the second linear section and the third linear section extend in the peripheral direction close to the rotor, and the permanent magnets are embedded in the magnet grooves. Wherein the included angle A between the second straight line section and the first straight line section meets the relational expression that A is larger than or equal to 140 degrees and smaller than or equal to 147.5 degrees, and the included angle B between the third straight line section and the first straight line section meets the relational expression that B is larger than or equal to 140 degrees and smaller than or equal to 147.5 degrees. The problem of poor back electromotive force sine of the motor in the prior art is solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of refrigeration equipment, in particular to a motor and a compressor. BACKGROUND

[0002] In the motor of the existing compressor, the magnet slot formed on the motor is usually in a linear or V-shaped type. The V-shaped magnet slot can make the motor have strong anti-demagnetization ability, reduce the thickness of the magnet, and further reduce the production cost of the motor. However, due to the zero-one distribution of the magnetic density distribution in the air gap of the motor with the V-shaped magnet slot, the sine difference of the back electromotive force of the motor is poor, which affects the overall performance of the motor. CONTENT OF THE UTILITY MODEL

[0003] The main purpose of the present application is to provide a motor and a compressor to at least solve the problem of the sine difference of the back electromotive force of the motor in the prior art.

[0004] According to one aspect of the present application, a motor is provided, comprising:

[0005] a rotor, a plurality of magnet slots are formed on the rotor and are arranged at intervals along the circumferential direction of the rotor, the magnet slots are arranged through along the axial direction of the rotor, and in the cross section of the rotor cut along the direction perpendicular to the axial direction of the rotor, the magnet slots comprise a first straight line segment, a second straight line segment and a third straight line segment, the median line of the first straight line segment passes through the axis of the rotor, the second straight line segment and the third straight line segment are symmetrically arranged at the two ends of the first straight line segment, and the second straight line segment and the third straight line segment respectively extend along the direction close to the outer periphery of the rotor;

[0006] a plurality of permanent magnets, the plurality of permanent magnets are respectively embedded in the first straight line segment, the second straight line segment and the third straight line segment;

[0007] a stator, a first through hole is arranged on the stator, and the stator is sleeved on the outer periphery of the rotor through the first through hole;

[0008] wherein, the included angle A between the second straight line segment and the first straight line segment satisfies the relationship: 140°≤A≤147.5°, and the included angle B between the third straight line segment and the first straight line segment satisfies the relationship: 140°≤B≤147.5°.

[0009] Further, a plurality of first rotor slots and a plurality of second rotor slots are formed on the outer periphery of the rotor, the plurality of first rotor slots are arranged at intervals, and the plurality of second rotor slots are arranged at intervals.

[0010] The second rotor slot is arranged between two adjacent magnet slots, and two first rotor slots are arranged on both sides of the second rotor slot.

[0011] Further, the second rotor slot comprises an outwardly expanding portion and an inwardly contracting portion.

[0012] The maximum distance from the inwardly contracting portion to the outer circumferential surface of the rotor is greater than the maximum distance from the outwardly expanding portion to the outer circumferential surface of the rotor.

[0013] Further, the minimum distance g1 between the outer circumferential surface of the rotor and the inner wall surface of the first through hole and the maximum distance g2 from the outwardly expanding portion to the inner wall surface of the first through hole satisfy the relationship: 3≤g2 / g1≤4; wherein 0.45mm≤g1≤0.55mm.

[0014] Further, two first rotor slots are arranged between two adjacent second rotor slots, and the two first rotor slots have an arc surface therebetween.

[0015] Further, the second rotor slot extends to the outer circumferential surface of the rotor, and the relative two side walls of the second rotor slot span an arc length corresponding to a central angle D of the outer circumferential surface of the rotor, and the central angle D satisfies the relationship: 14°≤D≤16°.

[0016] Further, the rotor further comprises a plurality of second through holes, and the plurality of second through holes penetrate the rotor along the axis direction of the rotor.

[0017] Further, the stator comprises a plurality of stator teeth, and the plurality of stator teeth are arranged on the side of the stator close to the rotor.

[0018] The maximum distance W1 between the two second through holes and the minimum width T of the stator tooth satisfy the relationship: T-W1≤1mm; and / or,

[0019] The permanent magnet comprises a first magnet, and the first magnet is embedded in the first straight line segment, and the length W2 of the first magnet and the maximum distance W1 between the two second through holes satisfy the relationship: W2=W1.

[0020] Further, the permanent magnets include a plurality of first magnets, a plurality of second magnets and a plurality of third magnets, each of the first magnets is embedded in each of the first linear segments, each of the second magnets is embedded in each of the second linear segments, and each of the third magnets is embedded in each of the third linear segments.

[0021] Wherein, the length W2 of the first magnet along the length direction of the first linear segment, the length W3 of the second magnet along the length direction of the second linear segment and the length W4 of the third magnet along the length direction of the third linear segment satisfy the relationship: W2≤W3=W4 or, W2≥W3=W4.

[0022] On the other hand, the application also provides a compressor, which includes the above motor.

[0023] Compared with the prior art, in the application, the magnet slot includes a first linear segment, a second linear segment and a third linear segment, the median line of the first linear segment passes through the axis of the rotor, the second linear segment and the third linear segment are symmetrically arranged at the two ends of the first linear segment, and the second linear segment and the third linear segment respectively extend along the direction close to the outer periphery of the rotor. The permanent magnet includes a plurality of, and the plurality of permanent magnets are respectively embedded in the first linear segment, the second linear segment and the third linear segment. At the same time, the included angle A between the second linear segment and the first linear segment satisfies the relationship: 140°≤A≤147.5°, and the included angle B between the third linear segment and the first linear segment satisfies the relationship: 140°≤B≤147.5°. That is to say, the included angle E between the extension line of the first linear segment and the extension line of the second linear segment should satisfy the relationship: 100°≤E≤115°. The direction of the magnetic force line emitted by the permanent magnet in the first linear segment, the second linear segment and the third linear segment is perpendicular to the direction of the permanent magnet. When E satisfies the above relationship, the magnetic force line emitted by the first linear segment and the third linear segment is emitted to the air gap corresponding to the outer periphery of the first linear segment, and there are less magnetic force lines in the air gap perpendicular to the first linear segment and the third linear segment. That is to say, the magnetic induction intensity of the magnetic field in the air gap corresponding to the first linear segment is the largest, and the magnetic induction intensity of the magnetic field in the air gap gradually decreases along the direction from the air gap corresponding to the first linear segment to the air gap corresponding to the second linear segment and the direction from the air gap corresponding to the first linear segment to the air gap corresponding to the third linear segment, and then gradually increases in the air gap through the next magnet slot, and the magnetic induction intensity of the magnetic field in the air gap decreases and then increases in turn along the circumferential direction, that is, the magnetic induction intensity of the magnetic field in the air gap conforms to the sinusoidal distribution. When the magnetic induction intensity of the magnetic field conforms to the sinusoidal distribution, the fluctuation of the magnetic field is reduced, thereby reducing the harmonic peak value of the back electromotive force on the stator 20, and finally making the waveform graph of the back electromotive force more tend to be sinusoidal, so as to improve the overall performance of the motor. BRIEF DESCRIPTION OF DRAWINGS

[0024] The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this application, illustrate embodiments of the application and together with the description serve to explain the application. In the drawings:

[0025] Figure 1 A cross-sectional structure diagram of the motor disclosed in the present application

[0026] Figure 2 A diagram of the relationship between the angle E and the peak value of back EMF Figure 1 A diagram of the relationship between the angle E and the peak value of back EMF

[0027] Figure 3 A diagram of the relationship between the angle E and the peak value of back EMF

[0028] Figure 4 A diagram of the relationship between the angle E and the peak value of back EMF

[0029] In the drawings, the following reference signs are used:

[0030] 10, rotor; 11, magnet slot; 12, second through hole; 13, first rotor slot; 14, second rotor slot; 20, stator; 21, stator tooth; 22, first through hole; 30, permanent magnet; 31, first magnet; 32, second magnet; 33, third magnet; 40, air gap; 111, first straight line segment; 112, second straight line segment; 113, third straight line segment; 141, outwardly expanded portion; 142, inwardly retracted portion. DETAILED DESCRIPTION

[0031] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0032] It should be noted that the terms used herein are only intended to describe specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, the singular form is intended to include the plural form unless the context clearly indicates otherwise, and it should be understood that, when the terms "comprise" and / or "include" are used in this specification, there is a presence of the features, steps, operations, devices, components and / or combinations thereof.

[0033] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps described in these embodiments do not limit the scope of this application. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following drawings denote similar items; therefore, once an item is defined in one drawing, it need not be further discussed in subsequent drawings.

[0034] See Figures 1 to 4 As shown, according to an embodiment of this application, a compressor is provided, which includes a motor, the motor including: a rotor 10, a permanent magnet 30 and a stator 20.

[0035] The rotor 10 has multiple magnet slots 11 spaced circumferentially along its axis. These slots extend through the rotor 10. In a cross-section obtained by cutting the rotor 10 perpendicular to its axis, each magnet slot 11 includes a first straight segment 111, a second straight segment 112, and a third straight segment 113. The perpendicular bisector of the first straight segment 111 passes through the axis of the rotor 10. The second and third straight segments 112 and 113 are symmetrically positioned at both ends of the first straight segment 111, extending along the outer periphery of the rotor 10. Multiple permanent magnets 30 are embedded within the first, second, and third straight segments 111 and 112, respectively. The stator 20 has a first through hole 22, through which it is fitted onto the outer periphery of the rotor 10. Among them, the angle A between the second line segment 112 and the first line segment 111 satisfies the relationship: 140°≤A≤147.5°, and the angle B between the third line segment 113 and the first line segment 111 satisfies the relationship: 140°≤B≤147.5°.

[0036] In the existing motor, the magnet slot 11 is mostly in the form of a straight line or V-shaped. In the straight line magnet slot 11, the magnetic force lines of the permanent magnet 30 are evenly arranged in the air gap 40 between the stator 20 and the rotor 10, resulting in a large harmonic of the back electromotive force on the stator 20, and finally causing a high waveform distortion rate of the back electromotive force. In the V-shaped magnet slot 11, the magnetic force lines between the permanent magnets 30 are more in the middle and less at both ends, and the magnetic force lines in the air gap 40 are respectively distributed as zero-one, which makes the waveform diagram of the back electromotive force in the form of a trapezoid, finally resulting in poor motor efficiency, large vibration, and large torque fluctuation.

[0037] In the embodiment, the magnet slot 11 comprises a first straight segment 111, a second straight segment 112 and a third straight segment 113. The median line of the first straight segment 111 passes through the axis of the rotor 10. The second straight segment 112 and the third straight segment 113 are symmetrically arranged at the two ends of the first straight segment 111, and extend along the direction close to the outer periphery of the rotor 10. The permanent magnet 30 comprises a plurality of permanent magnets 30, which are embedded in the first straight segment 111, the second straight segment 112 and the third straight segment 113, respectively. Meanwhile, the included angle A between the second straight segment 112 and the first straight segment 111 satisfies the relationship: 140°≤A≤147.5°, and the included angle B between the third straight segment 113 and the first straight segment 111 satisfies the relationship: 140°≤B≤147.5°. That is, the included angle E between the extension line of the first straight segment 111 and the extension line of the second straight segment 112 should satisfy the relationship: 100°≤E≤115°. The direction of the magnetic force line emitted by the permanent magnet 30 in the first straight segment 111, the second straight segment 112 and the third straight segment 113 is perpendicular to the permanent magnet 30. When E satisfies the above relationship, the magnetic force line emitted by the first straight segment 111 and the third straight segment 113 is emitted into the air gap 40 perpendicular to the outer periphery of the first straight segment 111. There are fewer magnetic force lines in the air gap 40 perpendicular to the first straight segment 111 and the third straight segment 113, that is, the magnetic induction intensity of the magnetic field in the air gap 40 corresponding to the first straight segment 111 is the largest, and gradually decreases along the direction from the air gap 40 corresponding to the first straight segment 111 to the air gap 40 corresponding to the second straight segment 112 and the direction from the air gap 40 corresponding to the first straight segment 111 to the air gap 40 corresponding to the third straight segment 113. After passing through the next magnet slot 11, the strength of the magnetic field in the air gap 40 gradually increases, and the strength of the magnetic field in the air gap 40 decreases and then increases in turn along the circumferential direction, that is, the magnetic induction intensity of the magnetic field in the air gap 40 conforms to the sinusoidal distribution. When the magnetic induction intensity of the magnetic field conforms to the sinusoidal distribution, the fluctuation of the magnetic field is reduced, thereby reducing the harmonic peak value of the back electromotive force on the stator 20, and finally making the waveform of the back electromotive force more sinusoidal, so as to improve the overall performance of the motor. If E is greater than 115°, the angle between the permanent magnets 30 is too large, and the magnetic force lines are difficult to converge at the air gap 40 corresponding to the first straight segment 111, so that the magnetic density in the air gap 40 corresponding to the first straight segment 111 is small, and the magnetic induction intensity of the magnetic field in the air gap 40 corresponding to the second straight segment 112 and the third straight segment 113 is lower, thereby reducing the peak value of the back electromotive force generated on the stator 20, and affecting the performance of the motor.If E is less than 100°, the magnetic field lines converge. The magnetic density in the air gap 40 corresponding to the first straight segment 111, the second straight segment 112, and the third straight segment 113 is relatively large and similar. This results in a large back EMF peak, causing the motor to heat up too quickly. Furthermore, the back EMF contains large harmonics, which reduces the motor's performance.

[0038] Furthermore, based on the above analysis, this application obtains the attached [parameter] by simulating the motor. Figure 3 The graph shows the relationship between angle E and the peak value of the back EMF. It can be observed that as the angle E increases, the peak value of the back EMF gradually decreases. To ensure that the peak value of the back EMF is within a moderate range, i.e., between 72V and 78V, and to avoid the back EMF being too large or too small and affecting the motor, the value of E in this application should be between 100° and 115°. The value of E can be 100°, 105°, 110°, or 115°.

[0039] Furthermore, a plurality of first rotor slots 13 and a plurality of second rotor slots 14 are provided on the outer periphery of the rotor 10. The plurality of first rotor slots 13 are spaced apart, and the plurality of second rotor slots 14 are spaced apart. A second rotor slot 14 is provided between two adjacent magnet slots 11. The first rotor slots 13 are provided on both sides of the second rotor slot 14, and the maximum slot depth of the second rotor slot 14 is greater than the maximum slot depth of the first rotor slot 13.

[0040] Specifically, in the prior art, the rotor 10 is not provided with the rotor slot, and when the magnetic force line passes through the rotor 10 to the air gap 40 between the rotor 10 and the stator 20, the magnetic induction intensity is uniformly distributed in the air gap 40, and the harmonic peak value in the back electromotive force generated on the stator 20 is large, and finally the waveform of the back electromotive force tends to be trapezoidal. In the embodiment, the rotor 10 is provided with the first rotor slot 13 and the second rotor slot 14, and the depth of the second rotor slot 14 is greater than that of the first rotor slot 13. It can be understood that when the magnetic force line passes through the rotor 10 to the first rotor slot 13, the direction of part of the magnetic force line changes, and the magnetic field generated by the part of the magnetic force line in the air gap 40 cannot generate the induced electromotive force on the stator 20, and finally the magnetic induction intensity of the magnetic field in the first rotor slot 13 which can affect the stator 20 is reduced. Similarly, when the magnetic force line enters the second rotor slot 14, the direction of the magnetic force line changes, and the magnetic induction intensity of the magnetic field in the second rotor slot 14 which can generate the induced electromotive force on the stator 20 is reduced. The maximum depth of the second rotor slot 14 is higher than that of the first rotor slot 13, so that in the process of the magnetic force line passing through the rotor 10, more magnetic force lines change direction at the second rotor slot 14, and fewer magnetic force lines change direction at the first rotor slot 13, and finally the effective magnetic induction intensity at the second rotor slot 14 is lower than that at the first rotor slot 13. Compared with the air gap 40 corresponding to the outer periphery of the rotor 10 which is not provided with the slot, the magnetic induction intensity at the air gap 40 is the largest, that is, the magnetic induction intensity in the air gap 40 decreases first and then increases along the circumferential direction, and finally the magnetic induction intensity in the air gap 40 is distributed in a sinusoidal manner, thereby reducing the harmonics in the back electromotive force on the stator 20, and the back electromotive force tends to be sinusoidal, thereby improving the overall performance of the motor.

[0041] Further, the second rotor slot 14 comprises an outwardly expanding portion 141 and an inwardly contracting portion 142, the outwardly expanding portion 141 expands outwardly away from the axis, and the two ends of the outwardly expanding portion 141 are respectively provided with the first rotor slot 13, and the inwardly contracting portion 142 is arranged in the outwardly expanding portion 141 and contracts inwardly towards the axis; the maximum distance from the inwardly contracting portion 142 to the outer periphery of the rotor 10 is greater than the maximum distance from the outwardly expanding portion 141 to the outer periphery of the rotor 10.

[0042] Specifically, since the maximum distance from the inwardly contracting portion 142 to the outer periphery of the rotor 10 is greater than the maximum distance from the outwardly expanding portion 141 to the outer periphery of the rotor 10, the magnetic induction intensity in the air gap 40 corresponding to the inwardly contracting portion 142 is the lowest, corresponding to the lowest point in the sine wave. Since the outwardly expanding portion 141 gradually expands outwardly away from the axis, the magnetic induction intensity of the magnetic field in the air gap 40 corresponding to the outwardly expanding portion 141 changes uniformly, that is, the magnetic density gradually decreases from the outer end of the outwardly expanding portion 141 to the inwardly contracting portion 142, and the magnetic density gradually increases from the inwardly contracting portion 142 to the outer end of the outwardly expanding portion 141.

[0043] Further, the minimum distance g1 between the outer circumferential surface of the rotor 10 and the inner wall surface of the first through hole 22 and the maximum distance g2 between the flared portion 141 and the inner wall surface of the first through hole 22 satisfy the relationship: 3≤g2 / g1≤4; wherein 0.45mm≤g1≤0.55mm.

[0044] In the present embodiment, if the maximum distance between the flared portion 141 and the outer circumferential surface of the rotor 10 is too large, such as g2 / g1>4, the magnetic density in the air gap 40 corresponding to the flared portion 141 will decrease too much relative to the magnetic density in the air gap 40 corresponding to the first rotor slot 13, ultimately resulting in a lower peak value of the back electromotive force at a certain moment, thereby affecting the performance of the motor. Meanwhile, if the maximum distance between the flared portion 141 and the outer circumferential surface of the rotor is too large, the second rotor slot 14 will be too deep, thereby affecting the rigidity of the rotor 10. If g2 / g1 is too small, such as g2 / g1<3, the magnetic density in the air gap 40 corresponding to the first rotor slot 13 will differ less from the magnetic density in the air gap 40 corresponding to the second rotor slot 14, in which case the peak value of the harmonics in the back electromotive force will be larger, and the probability of waveform distortion of the back electromotive force will be higher. In addition, in order to make the peak value of the back electromotive force moderate, the value of g1 in the present embodiment should be set to be between 0.45mm and 0.55mm. The size of g1 determines the size of the peak value of the back electromotive force, when g1 is small, the back electromotive force generated on the stator 20 is large, and when g1 is large, the back electromotive force generated on the stator 20 is small. If the back electromotive force is too large, it will cause the temperature rise of the motor to be too high, resulting in overheating of the motor, and if the back electromotive force is too low, it will cause the efficiency of the motor to be low, and the service life of the motor to decrease. Therefore, when the value of g1 is set to be between 0.45mm and 0.55mm, the peak value of the back electromotive force in the motor is moderate. The value of g1 can be 0.45mm, 0.46mm, 0.47mm, 0.48mm, 0.49mm, 0.5mm, 0.51mm, 0.52mm, 0.53mm, 0.54mm and 0.55mm. The value of g2 / g1 can be 3, 3.2, 3.4, 3.6, 3.8 and 4.

[0045] The present application also gives the following specific embodiments to illustrate the influence of g2 / g1 on the sinusoidalization of the back electromotive force waveform:

[0046] Embodiment 1:

[0047] g2 / g1 is 3, in which case the waveform distortion rate of the back electromotive force is 3.9%.

[0048] Embodiment 2:

[0049] g2 / g1 is 3.5, in which case the waveform distortion rate of the back electromotive force is 3.83%.

[0050] Embodiment 3:

[0051] g2 / g1 is 4, at this time the waveform distortion rate of back electromotive force is 3.76%.

[0052] Comparative Example 1:

[0053] g2 / g1 is 1, at this time the waveform distortion rate of back electromotive force is 11.1%.

[0054] Comparative Example 2:

[0055] g2 / g1 is 1.5, at this time the waveform distortion rate of back electromotive force is 8.3%.

[0056] Comparative Example 3:

[0057] g2 / g1 is 2, at this time the waveform distortion rate of back electromotive force is 6.4%.

[0058] Comparative Example 4:

[0059] g2 / g1 is 2.5, at this time the waveform distortion rate of back electromotive force is 5.2%.

[0060] According to the above Figure 4 It can be found from the above comparative examples and embodiments that when the ratio of g2 / g1 increases, the waveform distortion rate of back electromotive force gradually decreases, and when g2 / g1 is 3, the waveform distortion rate decreases to 3.9%, that is, the harmonic peak value in the back electromotive force is low, and the interference to the fundamental wave is small, and the waveform of the back electromotive force tends to be sinusoidal. In order to avoid that the waveform distortion rate of back electromotive force is too high, the waveform distortion rate of back electromotive force should be controlled within 5% in general, and therefore the preferred value of g2 / g1 in the present embodiment is between 3 and 4.

[0061] Further, two first rotor slots 13 are arranged at intervals between the two adjacent second rotor slots 14, and the two first rotor slots 13 have an arc surface therebetween, and the central angle C corresponding to the arc surface satisfies the relationship: 19°≤C≤21°.

[0062] Specifically, the magnetic force lines emitted by the permanent magnet 30 in the magnet slot 11 are gathered on the arc surface, and the magnetic force lines at the arc surface are more than those at the first rotor slot 13, while the magnetic force lines at the first rotor slot 13 are more than those at the second rotor slot 14. At this time, the magnetic density at the air gap 40 outside the arc surface is higher than that at the air gap 40 at the first rotor slot 13, and the magnetic density at the air gap 40 at the first rotor slot 13 is higher than that at the air gap 40 at the second rotor slot 14, that is, along the direction of the arc surface, the first rotor slot 13 and the second rotor slot 14, the magnetic density of the air gap 40 decreases in turn, and then along the direction of the second rotor slot 14, the first rotor slot 13 and the arc surface, the magnetic density in the air gap 40 increases in turn, so that the magnetic density in the air gap 40 conforms to the sinusoidal distribution. At the same time, it can be understood that the magnetic density in the air gap 40 corresponding to the arc surface is the maximum value, if the central angle C of the arc surface is large, such as C is greater than 21°, at this time the arc surface is large, the magnetic density in the air gap 40 corresponding to the arc surface is almost the same, finally the magnetic density distribution of the whole air gap 40 does not conform to the sinusoidal distribution. When C is less than 19°, at this time the arc surface is small, the magnetic density distribution of the whole air gap 40 is trapezoidal, which finally leads to high waveform distortion rate of the back electromotive force. The value of C can be 19°, 19.5°, 20°, 20.5° and 21°.

[0063] In addition, the second rotor slot 14 extends to the outer circumferential surface of the rotor 10, and the central angle D of the arc length corresponding to the two opposite side walls of the second rotor slot 14 across the outer circumferential surface of the rotor 10 satisfies the relationship: 14°≤D≤16°.

[0064] That is, the second rotor slot 14 should not be too large in the outer circumferential area of the rotor 10 slot, that is, when D is greater than 16°, at this time the second rotor slot 14 is set to be large, which will lead to the reduction of the structural strength of the rotor 10, and further reduce the service life of the motor. If D is less than 14°, the second rotor slot 14 is set to be small, which will make the magnetic density in the air gap 40 corresponding to the second rotor slot 14 decrease less, so as to make the magnetic density in the whole air gap 40 present a sinusoidal distribution. The value of D can be 14°, 14.5°, 15°, 15.5° and 16°.

[0065] As shown in the accompanying drawings, Figure 2 The rotor 10 also includes a plurality of second through holes 12, the plurality of second through holes 12 penetrate the rotor 10 along the axis direction of the rotor 10, and at least two second through holes 12 are arranged at intervals on the side of each magnet slot 11 close to the outer circumferential surface of the rotor 10.

[0066] In the embodiment, the second through hole 12 is used to isolate the magnetic force lines, that is, when the magnetic force lines emitted by the permanent magnets 30 at the second straight line segment 112 and the third straight line segment 113 meet the second through hole 12, the magnetic force lines will not pass through the second through hole 12 to the air gap 40. The design of the present application can avoid too many magnetic force lines passing through the arc surface, which leads to too high magnetic density in the air gap 40 corresponding to the arc surface, and further leads to too large peak value of the back electromotive force.

[0067] In addition, compared with the one-dimensional magnet slot 11, if the same permanent magnets 30 as the one-dimensional magnet slot 11 are arranged in the magnet slot 11 of the present application, the change of the magnetic field in the air gap 40 of the present application is uniform, the fluctuation of the magnetic field is small, and the anti-demagnetization effect of the motor is improved, so that the anti-demagnetization effect of the present application is better when the same size permanent magnets 30 are used. In one specific embodiment, the thickness of the permanent magnets 30 in the motor of the present application is 1.6 mm, and the thickness of the permanent magnets 30 in the motor with the one-dimensional magnet slot 11 is 1.8 mm. The anti-demagnetization effect of the motor of the present application is consistent with that of the motor with the one-dimensional magnet slot 11. On the other hand, compared with the existing motor with the V-shaped magnet slot 11, the arrangement of the magnet slot 11 of the motor of the present application makes the magnetic density distribution of the magnetic field formed by the permanent magnets 30 in the air gap 40 tend to be sinusoidal, while the permanent magnets 30 in the V-shaped magnet slot 11 are relatively concentrated, so that at least four second through holes 12 are arranged between the magnet slot 11 and the outer circumferential surface of the rotor 10 to make the magnetic density of the magnetic field in the air gap 40 be sinusoidal, while in the present embodiment, only two second through holes 12 are needed.

[0068] Further, the stator 20 includes a plurality of stator teeth 21, the plurality of stator teeth 21 are arranged at intervals on the side of the stator 20 close to the rotor 10, two second through holes 12 are arranged between each magnet slot 11 and the outer circumferential surface of the rotor 10, and the two second through holes 12 are symmetrically arranged along the perpendicular bisector of the first straight line segment 111; wherein the maximum distance W1 between the two second through holes 12 and the minimum width T of the stator tooth 21 satisfy the relationship: T-W1≤1mm.

[0069] Specifically, the magnetic force lines emitted by the permanent magnet 30 in the first straight segment 111 can pass through the two second through holes 12 and be emitted along the arc surface. When the maximum spacing W1 between the two second through holes 12 and the minimum width T of the stator tooth 21 satisfy the above relationship, the width of the stator tooth 21 is close to the maximum spacing between the two second through holes 12 at this time, and the magnetic force lines emitted by the arc surface can mostly pass into the stator tooth 21, thereby generating a back electromotive force in the stator 20. If T-W1>1mm, the maximum width of the stator tooth 21 and the maximum spacing between the two second through holes 12 are far apart, which can be due to the minimum width T of the stator tooth 21 being set too large, which will result in a decrease in the number of stator slots opened on the stator, ultimately affecting the output stability of the motor; it can also be due to the maximum spacing W1 between the two second through holes 12 being set too small, and the maximum spacing W1 being set too small will cause most of the magnetic force lines on the first straight segment 111, the second straight segment 112 and the third straight segment 113 to be shielded by the second through hole 12, ultimately resulting in a smaller magnetic field density in the air gap corresponding to the arc surface, and thus a lower back electromotive force.

[0070] Optionally, the permanent magnet 30 includes a first magnet 31 embedded in the first straight segment 111, and the length W2 of the first magnet 31 and the maximum spacing W1 between the two second through holes 12 satisfy the relationship: W2=W1. In this embodiment, the length W2 of the first magnet 31 should be as close as possible to the maximum spacing W1 between the two second through holes 12, that is, the magnetic force lines generated by the first magnet 31 can all pass through the maximum spacing between the two second through holes 12 and be emitted by the arc surface.

[0071] Further, the permanent magnet 30 includes a plurality of first magnets 31, a plurality of second magnets 32 and a plurality of third magnets 33, each first magnet 31 is embedded in each first straight segment 111 one by one, each second magnet is embedded in the second straight segment 112 one by one, and each third magnet 33 is embedded in the third straight segment 113 one by one. Among them, the length W2 of the first magnet 31 along the length direction of the first straight segment 111, the length W3 of the second magnet 32 along the length direction of the second straight segment 112 and the length W4 of the third magnet 33 along the length direction of the third straight segment 113 satisfy the relationship: W2≤W3=W4 or, W2≥W3=W4.

[0072] In some embodiments, W2, W3 and W4 are set to be the same, in which case the first magnet 31, the second magnet 32 and the third magnet 33 adopt the same size, facilitating manufacturing and processing. In some embodiments, W2 is smaller than W3 and W4, i.e. the first magnet 31 adopts a smaller size, in which case the design of the first straight line segment 111, the second straight line segment 112 and the third straight line segment 113 is facilitated, avoiding the first straight line segment 111 being too large, which makes it difficult to open the second straight line segment 112 and the third straight line segment 113. In addition, W2 can also be greater than W3 and W4, i.e. the first magnet 31 can adopt a larger size, so as to increase the number of magnetic field lines passing through the arc surface.

[0073] In summary, in the motor of the present application, the magnet slot 11 includes the first straight line segment 111, the second straight line segment 112 and the third straight line segment 113, by limiting the included angle A between the first straight line segment 111 and the second straight line segment 112 and the included angle B between the first straight line segment 111 and the third straight line segment 113, so that the magnetic density distribution in the air gap 40 tends to be sinusoidal, thereby reducing the size of the harmonic of the back electromotive force on the stator 20, so that the waveform of the back electromotive force tends to be sinusoidal, so as to improve the overall performance of the motor. In addition, in the motor of the present application, the outer periphery of the rotor 10 is provided with the first rotor slot 13 and the second rotor slot 14, and the depth of the second rotor slot 14 is greater than that of the first rotor slot 13. One advantage of this arrangement is that along the direction of the arc surface, the first rotor slot 13 and the second rotor slot 14, the magnetic density in the air gap 40 tends to decrease smoothly, thereby making the magnetic density distribution in the air gap 40 more sinusoidal. On the other hand, by limiting the value of g2 / g1, the present embodiment further reduces the peak value of the harmonic of the back electromotive force, thereby avoiding excessive interference of the harmonic with the fundamental wave, thereby causing the waveform distortion rate of the back electromotive force to be too large. On the other hand, the present application also limits the central angle C corresponding to the arc surface and the central angle D corresponding to the arc length across the outer periphery of the rotor 10 of the two side walls of the second rotor slot 14, thereby preventing the air gap 40 from varying unevenly in the axial direction, which ultimately leads to the waveform distortion rate of the back electromotive force being too large.

[0074] For purposes of the description hereinafter, the terms "upper", "lower", "right", "left", "rear", "front", "vertical", "horizontal", and derivatives thereof shall relate to the application as oriented in the drawing figures. However, it is to be understood that the application can assume various alternative orientations and, accordingly, such terms are not to be taken as limitations of the present application. All such modifications and variations are considered to be within the scope of the application as defined by the appended claims, the principles and their applications.

[0075] In addition, it should be noted that the terms "first", "second", and so on, used in the description and in the claims are used to differentiate between similar elements and are not necessarily used in a chronological or sequential manner, unless otherwise stated. Thus the above terms are to be understood as having a relative meaning and are used for the purpose of nomenclature only.

[0076] The preferred embodiments of the application are described herein with reference to the drawings, in which elements are illustrated by reference numbers employed in the drawings below. The drawings and the associated descriptions are provided to illustrate preferred embodiments of the application and are not intended to limit the scope of the application. In the drawings:

Claims

1. An electric machine characterized in that, The rotor (10) is provided with a plurality of magnet grooves (11) arranged at intervals in the circumferential direction of the rotor (10), the magnet grooves (11) are arranged through in the axial direction of the rotor (10), and in the cross section of the rotor (10) cut along a direction perpendicular to the axial direction of the rotor (10), the magnet grooves (11) comprise a first straight segment (111), a second straight segment (112) and a third straight segment (113), the median of the first straight segment (111) passes through the axis of the rotor (10), the second straight segment (112) and the third straight segment (113) are symmetrically arranged at the two ends of the first straight segment (111), and the second straight segment (112) and the third straight segment (113) respectively extend in the direction close to the outer circumference of the rotor (10); A plurality of permanent magnets (30) are embedded in the first straight segment (111), the second straight segment (112) and the third straight segment (113) respectively; The stator (20) is provided with a first through hole (22), and the stator (20) is sleeved on the outer circumference of the rotor (10) through the first through hole (22); Wherein, the included angle A between the second straight segment (112) and the first straight segment (111) satisfies the relationship: 140°≤A≤147.5°, and the included angle B between the third straight segment (113) and the first straight segment (111) satisfies the relationship: 140°≤B≤147.5°. A plurality of first rotor grooves (13) and a plurality of second rotor grooves (14) are arranged on the outer circumference of the rotor (10), a plurality of first rotor grooves (13) are arranged at intervals, and a plurality of second rotor grooves (14) are arranged at intervals; 2. The electric machine of claim 1, wherein, Wherein, one second rotor groove (14) is arranged between two adjacent magnet grooves (11), the first rotor grooves (13) are arranged on the two sides of the second rotor groove (14) respectively, and the maximum groove depth of the second rotor groove (14) is greater than the maximum groove depth of the first rotor groove (13). The second rotor groove (14) comprises an outward expanding portion (141) and an inward shrinking portion (142), the outward expanding portion (141) expands outward in a direction away from the axis, the first rotor grooves (13) are arranged at the two ends of the outward expanding portion (141) respectively, and the inward shrinking portion (142) is arranged in the outward expanding portion (141), and the inward shrinking portion (142) shrinks inward in a direction close to the axis; 3. The electric machine of claim 2, wherein, The maximum distance from the inward shrinking portion (142) to the outer circumferential surface of the rotor (10) is greater than the maximum distance from the outward expanding portion (141) to the outer circumferential surface of the rotor (10). The minimum distance g1 between the outer circumferential surface of the rotor (10) and the inner wall surface of the first through hole (22) and the maximum distance g2 between the outward expanding portion (141) and the inner wall surface of the first through hole (22) satisfy the relationship: 3≤g2 / g1≤4; wherein, 0.45mm≤g1≤0.55mm.

4. The electric machine of claim 3, wherein, ​ 5. The electric machine of claim 2, wherein, Two first rotor grooves (13) are arranged between two adjacent second rotor grooves (14) and have an arc surface, and the central angle C corresponding to the arc surface satisfies the relationship: 19°≤C≤21°.

6. The electric machine of claim 2, wherein, The second rotor groove (14) extends to the outer circumferential surface of the rotor (10), and the central angle D of the corresponding arc length of the two opposite side walls of the second rotor groove (14) across the outer circumferential surface of the rotor (10) satisfies the relationship: 14°≤D≤16°.

7. The electric machine of any one of claims 1 to 6, characterized by The rotor (10) further comprises a plurality of second through holes (12) penetrating the rotor (10) along the axial direction of the rotor (10), and at least two second through holes (12) are arranged on the side of each magnet groove (11) close to the outer circumferential surface of the rotor (10).

8. The electric machine of claim 7, wherein, The stator (20) comprises a plurality of stator teeth (21) arranged on the side of the stator (20) close to the rotor (10), and two second through holes (12) are arranged between each magnet groove (11) and the outer circumferential surface of the rotor (10), and the two second through holes (12) are symmetrically arranged along the perpendicular bisector of the first straight line segment (111). Wherein, the maximum distance W1 between the two second through holes (12) and the minimum width T of the stator tooth (21) satisfy the relationship: T-W1≤1mm; and / or, The permanent magnet (30) comprises a first magnet (31) embedded in the first straight line segment (111), and the length W2 of the first magnet (31) and the maximum distance W1 between the two second through holes (12) satisfy the relationship: W2=W1.

9. The electric machine of any one of claims 1 to 6, wherein, The permanent magnet (30) comprises a plurality of first magnets (31), a plurality of second magnets (32) and a plurality of third magnets (33), each first magnet (31) is embedded in each first straight line segment (111) one by one, each second magnet is embedded in the second straight line segment (112) one by one, and each third magnet (33) is embedded in the third straight line segment (113) one by one. Wherein, the length W2 of the first magnet (31) along the length direction of the first straight line segment (111), the length W3 of the second magnet (32) along the length direction of the second straight line segment (112), and the length W4 of the third magnet (33) along the length direction of the third straight line segment (113) satisfy the relationship: W2≤W3=W4 or, W2≥W3=W4.

10. A compressor characterized by, The compressor comprises the motor of any one of claims 1 to 9.

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