Stator core, permanent magnet motor and variable frequency compressor

Abstract

The application provides a stator core, a permanent magnet motor and a variable frequency compressor, relates to the technical field of compressor design and manufacturing, and comprises a plurality of stator teeth which are uniformly distributed along the inner diameter of the stator core, a stator yoke is formed between two adjacent stator teeth, a stator slot is formed between the two adjacent stator teeth and the stator yoke, the outer contour of the stator core comprises a first circular arc and a second circular arc, the radius of the first circular arc is R3, the radius of the second circular arc is R4, the first straight line and the second straight line are parallel and the distance therebetween is W; the third straight line and the fourth straight line are parallel to each other and the distance therebetween is H; the number of stator slots is Q, the radius of the inner diameter of the stator core is R1, and the radius of the circular contour formed by the bottom of the stator slot is R2; the dimensions satisfy the following conditions: 5.6<=Qx(R3-R2) / ((R3-R1)xP) <=7.2 and 0.3<=(R3-R4) / (R3-R2) <=0.4; and R4<=H / 2<=W / 2<=R3. By limiting the position and size relationship between the first circular arc and the second circular arc, the natural frequency of the motor stator is improved, and the adverse effects caused by motor vibration and noise are reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of compressor design and manufacturing, in particular, relates to a stator core, a permanent magnet motor and a variable frequency compressor. BACKGROUND

[0002] The variable frequency compressor is configured with a frequency converter and a rare earth permanent magnet motor, and can dynamically and steplessly adjust the running speed, and can run at a speed higher than the rated speed in the initial start-up period to realize rapid refrigeration or heating, and when the set temperature is reached, the variable frequency compressor runs at a low frequency, low power consumption, low power and low noise, is high in energy efficiency, and has a comprehensive energy efficiency ratio much higher than that of the fixed frequency compressor. At present, the variable frequency compressor has become the mainstream of household or commercial refrigeration and heating equipment due to its advantages of comfort, energy saving and reliability.

[0003] The motor as the driving power source of the compressor is an important component of the compressor product, and the performance and vibration of the motor directly affect the overall performance of the compressor and the user experience. The motor of the fully-closed scroll compressor is located below the refrigerant compression chamber, and a certain flow area needs to be provided on the radial section of the motor core for the needs of refrigerant circulation and motor cooling. The larger the flow area is, the higher the passing efficiency of the refrigerant is, the better the motor cooling effect is, and the better the motor performance is. However, increasing the flow area will reduce the size of the stator yoke and affect the magnetic circuit of the stator yoke, and will also reduce the contact area of the compressor shell and the stator core, so that the stiffness of the core is small, and the noise and vibration of the compressor are deteriorated. The flow area of the refrigerant in the prior art is small, the motor cooling effect is poor, and the oil return effect of the compressor is poor. Increasing the flow area will affect the stiffness of the motor, and cause the noise and vibration of the compressor to deteriorate.

[0004] The present application provides a kind of stator core in the condition of not affecting stiffness increases flow area. SUMMARY

[0005] To solve the above problems, the present application provides a stator core, a permanent magnet motor and a variable frequency compressor. The present application increases the flow area at the outer circle of the stator, improves the magnetic field distribution and trend of the yoke, and other measures without reducing the stiffness of the core, to improve the motor cooling and improve the stable operation ability of the compressor oil return system, improve the efficiency of the motor and the compressor, and reduce the vibration and noise of the motor and the compressor.

[0006] The technical means adopted by the present application are as follows:

[0007] The stator core comprises a plurality of stator teeth uniformly distributed along the inner diameter of the stator core, a stator yoke is formed between two adjacent stator teeth, a stator slot is formed between the two adjacent stator teeth and the stator yoke, the outer contour of the stator core comprises a first circular arc and a second circular arc, the radius of the first circular arc is R3, the radius of the second circular arc is R4, the stator core takes a first straight line, a second straight line, a third straight line and a fourth straight line as boundaries, the first straight line and the second straight line are parallel and the distance between them is W; the third straight line and the fourth straight line are parallel to each other and the distance between them is H; the number of stator slots is Q, the inner diameter of the stator core is R1, and the radius of the circular contour formed by the bottom of the stator slot is R2.

[0008] The dimensions satisfy: 5.6≤Q×(R3-R2) / ((R3-R1)×p)≤7.2 and 0.3≤(R3-R4) / (R3-R2)≤0.4; R4≤H / 2≤W / 2≤R3.

[0009] Further, the second circular arc and the outer diameter circular contour of the stator core form a plurality of refrigerant flow channels, the total area of the plurality of refrigerant flow channels is S; the first circular arc and the maximum outer diameter circular contour of the stator core coincide, the length of the coinciding part is L, L, R3 and S satisfy 0.25≤L / (2π×R3)≤0.6; 0.03≤S / π(R3)²≤0.15.

[0010] Further, the radius R3 of the first circular arc satisfies: 85mm≤R3≤95mm.

[0011] Further, the first circular arc and the second circular arc are connected by a straight line segment, and the intersection of the straight line and the circular arc is chamfered by 0.2-0.5mm.

[0012] The application provides a permanent magnet motor, which comprises the stator core and a rotor core; the number of pole pairs of the rotor core is p, and 2≤p≤4.

[0013] Further, the relationship between the number Q of stator slots of the stator core and the number p of pole pairs of the rotor core satisfies Q / p=12.

[0014] The application also provides a variable frequency compressor comprising the permanent magnet motor.

[0015] Compared with the prior art, the application has the following advantages:

[0016] 1. On the basis of fixing the outer diameter of the stator core, the refrigerant flow area inside the compressor is ensured by cutting the stator yoke of the motor stator core, the temperature rise of the motor is improved, the loss is reduced, and the efficiency of the compressor is improved. At the same time, by limiting the position and size relationship between the first circular arc and the second circular arc, the natural frequency of the motor stator is improved, and the adverse effects of motor vibration and noise are reduced.

[0017] 2. The motor magnetic circuit is improved by cutting arc of the stator yoke, the iron loss of the stator yoke under low load is reduced, and the efficiency of the compressor unit under low load is improved. BRIEF DESCRIPTION OF DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor under the premise of the drawings.

[0019] Figure 1 It is a schematic diagram of the stator core of the present application.

[0020] Figure 2 It is a schematic diagram of the permanent magnet motor in the present application.

[0021] Figure 3 It is a comparison diagram of the motor temperature under rated working condition of the present application and the prior art.

[0022] Figure 4 It is a comparison diagram of the motor efficiency of the compressor under specific working condition of the present application and the prior art.

[0023] Figure 5 It is a comparison diagram of the oil amount in the oil pool under high speed working condition of the compressor of the present application and the prior art.

[0024] Figure 6 It is a comparison diagram of the vibration under high speed working condition of the compressor of the present application and the prior art.

[0025] In the figure: 1, permanent magnet motor; 11, stator core; 111, stator tooth; 112, stator yoke; 113, stator slot; 114, first straight line; 115, second straight line; 116, third straight line; 117, fourth straight line; 118, first circular arc; 119, second circular arc; 120, flow passage; 21, rotor core; 211, permanent magnet slot. DETAILED DESCRIPTION

[0026] 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 drawings and in combination with the embodiments.

[0027] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the accompanying drawings of the embodiments of the present application. Obviously, the described embodiments are only a part but not all of the embodiments of the present application. The description of the following at least one exemplary embodiment is actually only illustrative but not as any limitation to the present application and its application or use. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall into the scope of the present application.

[0028] It should be noted that the terms used herein are only intended to describe specific embodiments and are not intended to limit exemplary embodiments according to the present application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise, and it should be further understood that the terms "comprise" and / or "include" as used herein specify the presence of stated features, steps, operations, devices, components and / or combinations thereof.

[0029] Unless specifically stated otherwise, the relative arrangements of the components and steps illustrated in these embodiments and the numerical expressions and values set forth herein are not limiting but are intended to be illustrative only. It should be understood that the various techniques described herein can be used in connection with either or both of the embodiments or indeed in the context of any other type of apparatus, whether or not expressly described herein. For the purposes of summarizing the disclosure, certain aspects, advantages and features of the embodiments have been described above. It is to be understood that not necessarily all such advantages can be achieved in all embodiments of the disclosure. Thus, the above description does not imply any limitation on the scope of the application, and many changes, modifications and rearrangements of the features, steps and / or components can be made without departing from the spirit of the application, as defined by the appended claims. Therefore, other aspects and features of the present application are apparent to those skilled in the art from the foregoing description. The scope of the application should be determined by the following claims.

[0030] As Figures 1-2The present application provides a stator core and a permanent magnet motor, including a permanent magnet motor 1, a stator core 11 and a rotor core 21, the inner diameter radius of the stator core 11 is R1, the outer circular contour radius of the stator core 11 is R3, including a plurality of stator teeth 111 uniformly distributed along the inner diameter of the stator core, the stator yoke 112 is formed between two adjacent stator teeth 111, the adjacent two stator teeth 111 and the stator yoke 112 form the stator slot 113, the circular contour radius formed by the bottom of the stator slot 113 is R2, the number of stator slots 113 is Q, the first straight line 114 and the second straight line 115 are used as boundaries on both sides of the stator core 11, the two straight lines are parallel to each other, the distance is W, the third straight line 116 and the fourth straight line 117 are used as boundaries, the distance is H. The outer contour of the stator yoke 112 includes a first circular arc 118 and a second circular arc 119, the radius of the first circular arc 118 is the same as the outer circular contour radius of the stator core 11, which is R3, the radius of the second circular arc 119 is R4, the first straight line 114, the second straight line 115, the third straight line 116, the fourth straight line 117, the first circular arc 118, the second circular arc 119 and the maximum outer diameter contour circle of the stator form a plurality of flow channels 120. The rotor core 21 includes a plurality of permanent magnet grooves 211 uniformly distributed, the number of pairs of permanent magnet grooves 211 is p, that is, the number of pole pairs 2≤p≤4, and the permanent magnet grooves 211 are perpendicular to the radial direction of the rotor core 21. The electromagnetic noise is mainly generated by the radial component of the electromagnetic force wave acting on the stator tooth 111, and is propagated outward through the stator yoke 112. The size relationship satisfies: 5.6≤Q×(R3-R2) / ((R3-R1)×p)≤7.2 and 0.3≤(R3-R4) / (R3-R2)≤0.4, R1, R2, R3 are in mm, and R4≤H / 2≤W / 2≤R3, the greater the value, the greater the stiffness of the stator core 11, the higher the natural frequency, the smaller the radial vibration acceleration of the motor stator, the lower the motor vibration, and the noise generated is also reduced. The total area of the plurality of flow channels 120 is S, which needs to satisfy 0.1≤S / π(R3)²≤0.2 with respect to the maximum outer circular contour area of the stator. The greater the flow channel 120 area value, the better the motor cooling, and the higher the compressor efficiency under specific load. Improve the motor temperature rise, reduce the loss, improve the efficiency of the compressor under specific working conditions, and control the motor manufacturing cost under the premise of ensuring the efficiency of the motor. By cutting the arc of the stator yoke 112, enough refrigerant flow channels 120 are ensured inside the compressor, thereby improving the stable operation ability of the compressor oil return system and improving the reliability of the compressor system.

[0031] Preferably, the total length of the first circular arc 118 coinciding with the maximum outer diameter contour circle of the stator is L, and 0.25≤L / (2π×R3)≤0.6. Increasing the flow channel without affecting the total length L of the first circular arc 118, the size of the first circular arc 118 will affect the contact area of the compressor shell and the stator core, and the size ensures the support of the motor when the compressor shell and the stator core are interference fit.

[0032] In one embodiment of the present application, preferably, in the limited core space, to reduce the mold cost, further improve the magnetic field, each edge intersection can be chamfered by 0.2-0.5mm.

[0033] In one embodiment of the present application, preferably, a circular arc or a straight line can be added on the straight line as a motor core division and core manufacturing positioning mark.

[0034] It should be noted that the "prior art" appearing below specifically refers to the prior art that does not make the inner diameter radius of the stator core 11 R1, the circular contour radius formed by the bottom of the stator slot R2, and the maximum outer circular contour radius of the stator core R3 satisfy 5.6≤Q×(R3-R1) / ((R2-R1)×p)≤7.2 and 0.3≤(R3-R4) / (R3-R2)≤0.4, so that Q×(R3-R1) / ((R2-R1)×p)=4.8 and (R3-R4) / (R3-R2)=0.3. The other size limitations of the "prior art" are consistent with the present application.

[0035] As Figure 3 shown is a comparison chart of the motor temperature of the compressor at the rated operating condition using the stator core of the present application and the prior art. By optimizing the position and size of the refrigerant flow passage arc, increasing the flow passage area, and improving the stable operation capability of the compressor oil return system, the refrigerant flow and the motor cooling are improved, and the motor temperature is reduced by 6.1% at the rated operating condition, which proves the effectiveness of the present application.

[0036] As Figure 4 shown is a comparison chart of the efficiency of the compressor at the rated point (load torque 40Nm, speed 5400rpm) using the stator core of the present application and the prior art. Figure 5 From the comparison chart, it can be seen that the motor efficiency at a specific speed is improved by using the stator core of the present application.

[0037] As Figures 5-6 shown is a comparison chart of the transverse vibration of the compressor at high speed and specific load torque using the stator core of the present application and the prior art, and a comparison chart of the oil pool height of the compressor using the stator core of the present application and the prior art.

[0038] During the high-speed operation of the compressor, sufficient lubrication is required to reduce mechanical component wear, and insufficient oil in the oil pool affects the reliability of the compressor. From Figure 5 it can be seen that the oil pump volume provided by the oil pool is the same at the same speed, and the oil return speed is increased due to the increase of the refrigerant flow passage, and the oil volume in the oil pool is increased, which can improve the reliability of the compressor operation; from Figure 6It can be seen that, for the compressor in high-speed operation, the transverse vibration amplitude of the stator core of the embodiment of the present application is equivalent to that of the prior art at different rotating speeds, and the compressor vibration is not deteriorated under the condition of increased refrigerant flow area, proving the effectiveness of the stator core of the present application.

[0039] The present application proposes a permanent magnet motor, which adopts the above-mentioned stator core 11 and rotor core 21.

[0040] The present application also proposes a variable frequency compressor, which adopts the above-mentioned permanent magnet motor 1, wherein other structures and operations of the permanent magnet motor and the variable frequency compressor are known to those skilled in the art and will not be described herein.

[0041] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, but not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A stator core, characterized in that, The stator core comprises multiple stator teeth evenly distributed along its inner diameter. A stator yoke is formed between two adjacent stator teeth, and a stator slot is formed between two adjacent stator teeth and the stator yoke. The outer contour of the stator core includes a first arc and a second arc, which are connected by a straight line segment. The radius of the first arc is R3, which is equal to the radius of the outer contour of the stator core. The radius of the second arc is R4. The stator core is bounded by a first straight line, a second straight line, a third straight line, and a fourth straight line. A first arc and a second arc are provided between the first, second, third, and fourth straight lines, and the second arc is provided between the first arcs. The first and second straight lines are parallel with a distance of W. The third and fourth straight lines are parallel to each other with a distance of H. The number of stator slots is Q, the inner diameter radius of the stator core is R1, and the radius of the circular contour formed by the bottom of the stator slots is R2. The dimensions satisfy the following: 5.6≤Q×(R3-R2) / ((R3-R1)×p)≤7.2 and 0.3≤(R3-R4) / (R3-R2)≤0.4; R4≤H / 2≤W / 2≤R3, where p is the number of rotor core pole pairs.

2. The stator core according to claim 1, characterized in that, The second arc and the outer diameter of the stator core form multiple refrigerant flow channels, and the total area of ​​the multiple refrigerant flow channels is S; the length of the part of the first arc that overlaps with the outer diameter of the stator core is L, where L, R3 and S must satisfy 0.25≤L / (2π×R3)≤0.6; 0.03≤S / π(R3)²≤0.

15.

3. The stator core according to claim 1, characterized in that, The radius R3 of the first arc satisfies: 85mm≤R3≤95mm.

4. The stator core according to claim 1, characterized in that, All intersections of straight lines and arcs are chamfered by 0.2-0.5mm.

5. A permanent magnet motor, characterized in that, Includes the stator core and rotor core as described in any one of claims 1-4; the rotor core has p pole pairs, where 2≤p≤4.

6. The permanent magnet motor according to claim 5, characterized in that, The relationship between the number of stator slots Q in the stator core and the number of pole pairs p in the rotor core satisfies Q / p=12.

7. A variable frequency compressor, characterized in that, Includes the permanent magnet motor as described in claim 6.

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