CN113839476A

CN113839476A - Motor, compressor and refrigeration plant

Info

Publication number: CN113839476A
Application number: CN202111104570.1A
Authority: CN
Inventors: 张德金; 杨森; 邱小华
Original assignee: Guangdong Meizhi Compressor Co Ltd
Current assignee: Guangdong Meizhi Compressor Co Ltd
Priority date: 2021-09-18
Filing date: 2021-09-18
Publication date: 2021-12-24

Abstract

The invention discloses a motor, a compressor and refrigeration equipment, wherein the motor comprises: the stator is provided with a stator yoke part and 12 stator tooth parts arranged at intervals along the circumferential direction of the stator yoke part, and a stator slot is defined between every two adjacent stator tooth parts; each stator tooth part is provided with an arc end surface arranged towards the center of the motor, and the rotor is provided with 8 ferrite permanent magnets; wherein each stator slot has a slot opening facing the rotor, the width of each slot opening is a first width, and the ratio of the sum of the first widths to the circumference of the circle on which the arc end face of each stator tooth portion is located is not less than 0.14 and not more than 0.2. The technical scheme of the invention can reduce the motor noise in the refrigeration equipment.

Description

Motor, compressor and refrigeration plant

Technical Field

The invention relates to the technical field of motors, in particular to a motor, a compressor and refrigeration equipment.

Background

At present, refrigeration equipment such as a refrigerator and a freezer needs to be provided with a compressor to realize the refrigeration function, the type of the compressor in the equipment needs to be converted from a constant-speed compressor to a variable-frequency compressor along with the improvement of the energy efficiency grade requirement of the market on the refrigeration equipment, and a motor in the existing compressor can generate large noise under the variable-frequency control, so that the use experience of a user is influenced.

Disclosure of Invention

The invention mainly aims to provide a motor, and aims to solve the problem of overlarge noise of the motor in refrigeration equipment.

In order to achieve the above object, the present invention provides a motor including:

the stator is provided with a stator yoke portion and 12 stator tooth portions arranged at intervals along the circumferential direction of the stator yoke portion, and a stator slot is defined between every two adjacent stator tooth portions; each of the stator teeth has an arc end surface disposed toward a center of the motor, and,

a rotor having 8 ferrite permanent magnets;

each stator slot is provided with a slot opening facing the rotor, the width of each slot opening is a first width, and the ratio of the sum of the first widths to the circumference of a circle where arc end faces of the stator tooth parts are located is not less than 0.14 and not more than 0.2.

Optionally, each stator tooth portion comprises a tooth body and two tooth shoes oppositely arranged on the tooth body along the circumferential direction of the stator;

the first tooth shoe and the second tooth shoe are oppositely arranged between two adjacent tooth bodies, the first tooth shoe and the second tooth shoe define a notch corresponding to the stator slot, and the minimum relative position distance between the first tooth shoe and the second tooth shoe is a first width.

Optionally, the outer circumferential edge of the stator yoke has two opposite first sides and two opposite second sides, a maximum relative position distance between the two first sides is a first distance, a maximum relative position distance between the two second sides is a second distance, and the first distance is equal to the second distance.

Optionally, the diameter of a circle on which arc end faces of the stator teeth are located is a first diameter, and a ratio of the first diameter to the first distance is not less than 0.64.

Optionally, the second side edge includes a first straight-side section, a second straight-side section, and a connecting-side section connecting the first straight-side section and the second straight-side section, the number of the second straight-side section and the connecting-side section is two, and two ends of the first straight-side section are respectively connected with one of the second straight-side sections through one of the connecting-side sections;

the relative position distance between the second straight edge sections of the two second side edges is smaller than the relative position distance between the first straight edge sections of the two second side edges.

Optionally, the connecting edge section is arranged in a straight edge.

Optionally, the diameter of the circle on which the inner circumference of the stator yoke is located is a second diameter, and the ratio of the second diameter to the first distance is not less than 0.9.

Optionally, an air gap is provided between the stator and the rotor, and the width of the air gap is less than 0.5 mm.

The invention also provides a compressor, which comprises the motor.

The invention also provides refrigeration equipment, which comprises the motor;

or, alternatively, a compressor as described above.

The technical scheme of the invention is that a stator with 12 stator teeth and a rotor with 8 permanent magnets are adopted, a stator slot is defined between two adjacent stator teeth, each stator tooth is provided with an arc end face arranged towards the center of the motor, each stator slot is provided with a slot facing the rotor, the width of each slot is a first width, and the ratio of the sum of the first widths to the circumference of a circle where the arc end face of each stator tooth is located is not less than 0.14 and not more than 0.2. According to the technical scheme, a 12-slot 8-pole motor structure is adopted in the medium and small-volume refrigeration equipment, and the proportion of the sum of the widths of the notches to the circumference of the circle is limited to be not less than 0.14 and not more than 0.2, so that the air gaps between the arc end surfaces and the rotor and the proportion of the total width of the notches to the circumference are in a reasonable range, and the cogging torque of the notches and the noise generated when the motor works can be remarkably reduced.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the structures shown in the drawings without creative efforts.

Fig. 1 is a schematic structural diagram of a stator in an embodiment of an electric machine according to the present invention;

FIG. 2 is a schematic structural diagram of another embodiment of the motor of the present invention;

fig. 3 is a layout drawing of stator laminations formed by cutting in another embodiment of the motor of the present invention.

The reference numbers illustrate:

reference numerals	Name (R)	Reference numerals	Name (R)
				100	Stator	B	First width
110	Stator yoke	D1	First diameter
				111	The first side edge	D2	Second diameter
112	Second side edge	200	Rotor
				1121	A first straight section	210	Ferrite permanent magnet
1122	Second straight side section	300	Air gap
				1123	Connecting edge section	A1	First tooth boot
120	Stator tooth	A2	Second tooth boot
				121	Tooth body	S1	First distance
122	Tooth boots	S2	Second distance
				120	Stator slot	L1	First central line
130	Arc end face

The implementation, functional features and advantages of the objects of the present invention will be further explained with reference to the accompanying drawings.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In addition, the descriptions related to "first", "second", etc. in the present invention are only for descriptive purposes and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In addition, technical solutions between various embodiments may be combined with each other, but must be realized by a person skilled in the art, and when the technical solutions are contradictory or cannot be realized, such a combination should not be considered to exist, and is not within the protection scope of the present invention.

The invention provides a motor.

At present, a compressor in refrigeration equipment such as a refrigerator with a medium and small volume and a freezer with a medium and small volume generally adopts a 6-slot motor or a 9-slot motor to realize a refrigeration function, and the refrigeration equipment with the medium and small volume needs to be changed from constant speed control to variable frequency control along with the improvement of the requirement on the refrigeration equipment, but the motor structure of the 6-slot motor or the 9-slot motor is not suitable for variable frequency control, and overlarge noise can be generated during variable frequency control. For such a refrigerating device with medium and small volumes which is placed in a room, the noise level is an important index influencing the use comfort level, and the use comfort level of a user is influenced by excessive noise, so that how to reduce the noise generated by the refrigerating device with medium and small volumes to be suitable for frequency conversion control is a problem which is urgently solved at present.

In view of the above problem, referring to fig. 1 to 3, in an embodiment of the present invention, the motor includes:

a stator 100 having a stator yoke 110 and 12 stator teeth 120 arranged at intervals along a circumferential direction of the stator yoke 110, a stator slot 120 being defined between two adjacent stator teeth 120; each of the stator teeth 120 has an arc end surface 130 disposed toward the center of the motor, and,

a rotor 200 having 8 ferrite permanent magnets 210;

wherein each of the stator slots 120 has a slot opening facing the rotor 200, a width of each of the slot openings is a first width B, and a ratio of a sum of the first widths B to a circumference of a circle on which arc end faces 130 of each of the stator tooth portions 120 are located is not less than 0.14 and not more than 0.2.

In this embodiment, the stator 100, also called a stator core, may be formed by axially laminating a plurality of stator laminations. The stator 100 may include a stator yoke 110 and a plurality of stator teeth 120; the plurality of stator teeth 120 may be uniformly spaced on the stator yoke 110 and may be respectively disposed toward the center of the stator 100 or the rotor 200, and an end surface of each stator tooth 120 facing the rotor 200 may be an arc end surface 130 to improve an air gap 300 between the stator and the rotor 200, thereby reducing motor noise. In addition, any two adjacent stator teeth 120 may surround stator yoke 110 to form a stator slot 120 with an opening facing the center of stator 100, that is, the number of stator teeth 120 is the same as the number of stator slots 120. Each stator tooth 120 may be wound with a predetermined number of turns of electromagnetic wire to form a coil winding, and the electromagnetic wire is used to form corresponding magnetic poles on the wound stator tooth 120 when an alternating current is applied, so as to generate a torque to drive the rotor 200 to rotate.

The rotor 200, also called a rotor core, may be formed by axially laminating a plurality of rotor sheets. Each rotor punching sheet can have 8 permanent magnet 210 mounting holes, and 8 permanent magnet 210 mounting holes can be evenly set up at interval, and the permanent magnet 210 mounting holes on each rotor punching sheet can be when folding and pressing formation rotor 200, correspond the intercommunication in order to form the permanent magnet mounting groove to supply permanent magnet 210 to install and place. In this embodiment, the permanent magnet 210 is a ferrite permanent magnet 210, which can reduce the design cost and reduce the residual magnetism and air gap flux density, and in other embodiments, the permanent magnet 210 can also be implemented by using an alloy permanent magnet 210. It can be understood that the shape of the permanent magnet 210 needs to be matched with the shape of the permanent magnet mounting groove, and the permanent magnet 210 mounted in one permanent magnet mounting groove is one pole, while the motor of the compressor in the existing middle and small-volume refrigeration equipment is generally a 6-groove 4-pole or 9-groove 6-pole motor, and the least common multiple of the groove pole ratio is 12 or 18 respectively, and the applied technical scheme can effectively increase the fundamental wave frequency of the cogging torque of the motor by adopting a 12-groove 8-pole motor structure, and the least common multiple of the groove pole ratio can reach 24, and the increase of the fundamental wave frequency of the cogging torque can cause the amplitude of the fundamental wave to be reduced, so the noise caused by the cogging torque in the operation of the motor can be effectively reduced.

In practical applications, cogging torque is actually generated by interaction of stator slots 120 and permanent magnets 210, and specifically the change in permeance at air gap 300 caused by the slot opening of stator slots 120, i.e. the width of the slot opening has an effect on cogging torque. Because the 12-slot 8-pole motor structure has 12 stator slots 120, the arc end faces 130 of the 12 stator teeth 120 can be located on the same circumference as the existing motor design, and as the number of the stator slots 120 increases, if the arc end face 130 circumference design of the existing 6-slot 4-pole or 9-slot 6-pole motor is adopted, the proportion of the total width of each slot to the circumference where the arc end face 130 is located is too large, and then the cogging torque brought by the slots and the noise in the operation of the motor are too large, so that how to adopt the 12-slot 8-pole motor structure in the small and medium-volume refrigeration equipment and simultaneously reduce the cogging torque brought by the slots becomes a difficult point in the current industry.

According to the technical scheme, the radius of the circle where the arc end face 130 is located is increased, so that the circumference of the circle is increased, the proportion of the total width of each notch to the circumference of the arc end face 130 is reduced, the lower limit of the proportion of the sum of the widths of the notches to the circumference of the circle is limited to be greater than or equal to 0.14, and the upper limit of the ratio is limited to be not greater than 0.2; in other words, if the width of each notch is B and the diameter of the circle on which the arc end face 130 is located is D1, the above definition can be expressed as 0.14 ≦ 12 × B/Π × D1 ≦ 0.2. Therefore, when a 12-slot 8-pole motor structure is adopted in the middle and small-volume refrigeration equipment, the air gap 300 between each arc end face 130 and the rotor 200 and the proportion of the total width and the circumference of each slot are in a reasonable range, and practical verification shows that the motor structure adopting the proportional relation can obviously reduce the cogging torque of each slot and the noise generated during working. In addition, the width of each notch can be set to be equal or unequal according to actual needs, and is not limited herein.

Referring to fig. 1 to 3, in an embodiment of the present invention, each of the stator teeth 120 includes a tooth body 121 and two tooth shoes 122 oppositely disposed on the tooth body 121 along a circumferential direction of the stator 100;

a first tooth shoe a1 and a second tooth shoe a2 are oppositely arranged between two adjacent tooth bodies 121, the first tooth shoe a1 and the second tooth shoe a2 define a notch of the corresponding stator slot 120, and the minimum relative position distance between the first tooth shoe a1 and the second tooth shoe a2 is a first width B.

In this embodiment, a first end of the tooth body 121 may be connected to the stator yoke 110, and a second end thereof may be extended toward the center of the rotor 200. The two tooth slots can be separately arranged on two opposite sides of the second end of the tooth body 121, so that part of the outer end surface of the tooth shoe 122 and the end surface of the second end of the tooth body 121 can jointly form an arc end surface 130 of the stator tooth part 120; the tooth shoes 122 may be shaped like a shoe, and the width of each tooth shoe 122 may gradually decrease from one end connected with the tooth body 121 to the other end away from the tooth body 121, so that two opposite tooth shoes 122 are disposed between any two adjacent tooth bodies 121, one of which is the first tooth shoe a1, and the other is the second tooth shoe a 2. In other words, the stator 100 of the present application has 12 first tooth shoes a112 and second tooth shoes a 2. In this manner, the present application can reduce magnetic resistance and increase magnetic flux of the stator 100 using the tooth shoe 122 on the basis of reducing noise by setting the minimum relative position distance between the first tooth shoe a1 and the second tooth shoe a2 to the slot width.

Referring to fig. 1 to 3, in an embodiment of the present invention, the outer circumferential edge of the stator yoke 110 has two opposite first sides 111 and two opposite second sides 112, a maximum relative position distance between the two first sides 111 is a first distance S1, a maximum relative position distance between the two second sides 112 is a second distance S2, and the first distance S1 is equal to the second distance S2.

Stator yoke portion 110 is circular usually, and the stator punching is usually through stamping forming, because the restriction of stator punching appearance, the stock layout distance of stator punching is great in stamping process, and has too much material between the adjacent stator punching not utilized for the material waste is comparatively serious, has increased material cost, and then leads to motor and refrigeration plant's manufacturing cost to improve. In order to solve the above problem, in the present technical solution, the outer circumferential edge of the stator yoke 110 has two opposite first sides 111 and two opposite second sides 112, and the maximum relative position distance between the two first sides 111 is equal to the maximum relative position distance between the two second sides 112, so that the shape of the stator 100 of the present embodiment is substantially "square", which can effectively avoid the local magnetic flux density unevenness of the stator 100 caused by the large width difference of the stator yoke 110, and is beneficial to improving the stability of the frequency conversion control of the motor and reducing the noise generated when the motor works.

In addition, because stator 100 can be laminated by the stator punching that adopts the same shape and form, and the stator punching that is "square" compares in present circular shape stator punching, no matter through stamping forming, still laser cutting or water jet cutting, when carrying out the stock layout to the stator punching, the space between every two adjacent stator punching is few, can improve the utilization ratio of material, has reduced the waste of material to material cost has been reduced, and then has reduced the manufacturing cost of motor.

Referring to fig. 1 to 3, in an embodiment of the present invention, a diameter of a circle on which arc end surfaces 130 of the stator teeth 120 are located is a first diameter D1, and a ratio of the first diameter D1 to the first distance S1 is not less than 0.64.

In this embodiment, since the rotor 200 is an 8-pole design, i.e. there are 8 gaps between the permanent magnets 210, the leakage flux is increased and the air gap flux density is reduced. To solve the above problem, the outer diameter of the rotor 200 needs to be increased accordingly, so that the 8 ferrite magnets 210 can be distributed more uniformly in the rotor 200, and thus, the circumference of the circle where the arc end surface 130 is located needs to be increased correspondingly to meet the requirement of the outer diameter of the rotor 200. It is understood that as the circumference of the circle on which the arc end face 130 is located increases, the stator yoke 110 also needs to increase accordingly, and the present solution limits the ratio of the diameter of the circle on which the arc end face 130 is located to the first distance S1/second distance S2 of the "square" stator 100 to greater than or equal to 0.64; in other words, if the first distance S1/the second distance S2 is A and the diameter of the circle on which the arc end face 130 is located is D1, the above definition can be expressed as D1/A ≧ 0.64. Therefore, the rotor 200 hole formed by the circle of the arc end surface 130 can be matched with the rotor 200 with the increased outer diameter, and the air gap flux density is increased.

Referring to fig. 1 to fig. 3, in an embodiment of the present invention, the second side 112 includes a first straight-side section 1121, a second straight-side section 1122, and a connecting-side section 1123 connecting the first straight-side section 1121 and the second straight-side section 1122, the number of the second straight-side section 1122 and the connecting-side section 1123 is two, and two ends of the first straight-side section 1121 are respectively connected to one second straight-side section 1122 through one connecting-side section 1123;

the relative distance between the second straight sections 1122 of the two second sides 112 is smaller than the relative distance between the first straight sections 1121 of the two second sides 112.

In the present embodiment, the stator 100 has a horizontal center line passing through the center of the stator 100, which is defined as the first center line L1, and a vertical center line passing through the center of the stator 100, which is defined as the second center line. The two first straight sections 1121 of the two second side edges 112 may be symmetrically arranged with respect to a first central line L1 of the stator punching sheet, that is, the two second straight sections 1122 of the two second side plates are located on the same side of a second central line of the stator punching sheet, as shown in fig. 3; the two second straight sections 1122 of the two second side edges 112 may also be disposed in a central symmetry with respect to the center of the stator 100, that is, the two second straight sections 1122 of the two second side edges 1121 are respectively and correspondingly located at two sides of a second central line of the stator lamination.

In addition, in order to simultaneously ensure the uniformity of the width of the stator yoke 110, the two second straight-side segments 1122 have the same length, and the two connecting-side segments 1123 have the same length, that is, the two second straight-side segments 1122 and the two connecting-side segments 1123 of each second side 112 are symmetrically arranged about the second center line, the length of the first straight-side segment 1121 may be equal to twice the length of the second straight-side segment 1122 plus a preset length, and the preset length may be selected to be 1.5mm, and the relative position distance between the corresponding second straight-side segments 1122 in the two second sides 112 is set to be smaller than the relative position distance between the first straight-side segments 1121 in the two second sides 112, in other words, even if the first straight-side end is protruded compared with the second straight-side segments 1122 on the first side 111. So, when forming the stator punching through laser cutting or water jet cutting, every adjacent three stator punching can arrange "altogether", as shown in fig. 3, along the direction of second central line (vertical direction in the picture), two connection side sections 1123 of a stator punching that is located the top coincide with two stator punching that are located the below connection side sections 1123 that correspond respectively, so, compare in prior art, eliminated the clearance between every adjacent two stator punching, reduced the material waste, thereby improved the utilization ratio of material, reduced material cost.

Referring to fig. 1 to 3, in an embodiment of the present invention, the connecting edge section 1123 is arranged in a straight edge.

In this embodiment, the connecting edge sections 1123 are straight edges, so that when stator laminations are cut to form, adjacent stator laminations can be arranged in a 'common edge' manner, and the utilization rate of materials is improved; on the one hand, when the stator punching sheet passes through stamping forming, the arrangement interval of adjacent stator punching sheets can be reduced, and the utilization rate of materials is improved. Of course, in other embodiments, those skilled in the art may also employ, for example: the concave-convex structure, the wave-shaped structure or the zigzag structure and other splicing structures are used for improving the material utilization rate, and are not described in detail herein.

Referring to fig. 1 to 3, in an embodiment of the present invention, a diameter of a circle along which an inner circumference of the stator yoke 110 is located is a second diameter D2, and a ratio of the second diameter D2 to the first distance S1 is not less than 0.9.

It can be understood that, as the circumference of the circle on which the arc end face 130 is located is increased, the area of the stator slot 120 is reduced, specifically, the slot depth of the stator slot 120 in the radial direction of the rotor 200 is reduced, if the area of the stator slot 120 is maintained unchanged or reduced less, the first distance S1 and the second distance S2 are required to be increased, so as to make the stator 100 larger, which is not favorable for the miniaturization design of the motor. In this embodiment, the stator yoke 110 has an inner circumferential edge facing the center of the motor and connected to the first end of each tooth body 121, the inner circumferential edge is circular, and the diameter of the circle on which the inner circumferential edge is located, i.e., the second diameter D2, is in direct proportion to the depth of the stator slot 120. According to the technical scheme, the ratio of the second diameter D2 to the first distance S1 is limited to be greater than or equal to 0.9, in other words, if the second diameter D2 is D2, the limitation can be expressed as that D2/A is greater than or equal to 0.64. In this way, each stator slot 120 may have a sufficient slot depth to form a suitable area without increasing the first distance S1 and the second distance S2, which is advantageous for the miniaturized design of the motor.

Referring to fig. 1 to 3, in an embodiment of the present invention, an air gap 300 is provided between the stator 100 and the rotor 200, and a width of the air gap 300 is less than 0.5 mm.

The second end of the stator tooth portion 120 is spaced from the outer circumferential edge of the rotor 200 by a distance of less than 0.5 mm.

In practical applications, an air gap 300 exists between the stator 100 and the rotor 200, that is, a space between the arc end face 130 of each stator tooth 120 and the outer peripheral edge of the rotor 200, and the air gap 300 has rich harmonic content, and is prone to cause electromagnetic excitation force resonance, so that loud noise is generated and user experience is affected. The width direction of the air gap 300 may be arranged corresponding to the radial direction of the rotor 200, for example, if the width of the air gap 300 is too wide, the back electromotive force of the motor may decrease instead, which is unfavorable for the frequency conversion control of the motor, and may also result in an increase in magnetic resistance and an increase in excitation current, resulting in a decrease in power factor of the motor. It is understood that when the air gap 300 is a non-uniform width air gap 300, the width of the air gap 300 described in the present specification is the minimum width of the air gap 300. According to the technical scheme, the width of the air gap 300 is limited to be less than 0.5mm, although the air gap 300 with the narrower width can bring noise deterioration, the air gap is combined with an adopted 12-slot 8-pole motor structure, the order of electromagnetic exciting force can be improved, the deterioration of the electromagnetic exciting force to the motor noise is further reduced, and the comfort of small and medium-sized refrigerating equipment in an indoor use process is greatly improved. It can also be understood that the technical solution of the present invention defines an upper limit value of the width of the air gap 300, and a lower limit value thereof is determined by a rotation space margin between the stator 100 and the rotor 200, which is not limited herein.

The present invention further provides a compressor, which includes the motor as described above, and the specific structure of the motor refers to the above embodiments, and since the compressor adopts all technical solutions of all the above embodiments, the compressor at least has all the beneficial effects brought by the technical solutions of the above embodiments, and details are not repeated herein. Wherein, the compressor can include pivot, compression chamber and be located the piston assembly of compression chamber, and the both ends of pivot can be connected with piston assembly and electric motor rotor 200's transmission respectively to make electric motor rotor 200 when rotating, accessible pivot drive piston assembly reciprocates the multiple compression in the compression chamber, and then realizes discharging after the low temperature low pressure material compression that the compression chamber inserts is high temperature high pressure.

The invention further provides a refrigeration device, which includes the motor as described above, and the specific structure of the motor refers to the above embodiments, and since the refrigeration device adopts all the technical solutions of all the above embodiments, the refrigeration device at least has all the beneficial effects brought by the technical solutions of the above embodiments, and details are not repeated herein. Alternatively, the refrigeration equipment comprises the compressor as described above, and the specific structure of the compressor can refer to the above embodiments, which are also not described herein. Wherein, the refrigeration equipment can be an ice chest, a refrigerator or an air conditioner.

The above description is only an alternative embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications and equivalents of the present invention, which are made by the contents of the present specification and the accompanying drawings, or directly/indirectly applied to other related technical fields, are included in the scope of the present invention.

Claims

1. An electric machine, characterized in that the electric machine comprises:

a rotor having 8 ferrite permanent magnets;

2. The electric machine of claim 1, wherein each of the stator teeth includes a tooth body and two tooth shoes provided on the tooth body in opposition to each other in a circumferential direction of the stator;

3. The electric machine of claim 1, wherein the outer circumferential edge of the stator yoke has first and second opposing sides, a maximum relative position distance between the first sides being a first distance and a maximum relative position distance between the second sides being a second distance, the first distance being equal to the second distance.

4. The motor of claim 3 wherein said stator teeth arc ends lie on a circle having a diameter of a first diameter, the ratio of said first diameter to said first distance being no less than 0.64.

5. The motor according to claim 3, wherein the second side comprises a first straight section, a second straight section and a connecting side section connecting the first straight section and the second straight section, the number of the second straight section and the connecting side section is two, and two ends of the first straight section are respectively connected with the second straight section through one connecting side section;

6. An electrical machine according to claim 5, wherein the connecting edge section is straight.

7. The electric machine of claim 3, wherein a diameter of an inner circumference of the stator yoke along a circle is a second diameter, a ratio of the second diameter to the first distance being no less than 0.9.

8. The machine of claim 1 wherein said stator and said rotor have an air gap therebetween, said air gap having a width of less than 0.5 mm.

9. A compressor, characterized in that it comprises an electric motor according to any one of claims 1-8.

10. A refrigeration device, characterized in that it comprises an electric motor according to any one of claims 1-8;

alternatively, the refrigeration appliance comprises a compressor as claimed in claim 9.