Motor assembly, water pump and water heater

Abstract

The utility model discloses a motor assembly, a water pump and a water heater, and relates to the technical field of water pumps, the motor assembly comprises a stator and a rotor, the stator comprises a stator iron core, and the stator iron core is annular and is provided with an inner hole; the rotor is rotationally arranged in the inner hole and comprises a magnetic ring, and the surface magnetic flux density of the magnetic ring ranges from 1700 Gs to 2000 Gs. The surface magnetic flux density of the magnetic ring reaches 1700 Gs to 2000 Gs, the magnetic performance of the magnetic ring is enhanced, the power density of the motor assembly is improved, and therefore the motor assembly is suitable for the application environment with the high-performance requirement.

Description

TECHNICAL FIELD

[0001] The utility model relates to water pump technical field, especially a motor assembly, water pump and water heater. BACKGROUND

[0002] The water pump of the water heater takes the motor assembly as the power source, in order to respond to the water demand of user quickly, the performance requirement of water pump to motor assembly is higher, especially the performance of rotor magnet in motor assembly cannot match the performance of motor assembly. SUMMARY

[0003] The utility model discloses at least one of the technical problems in the prior art is solved, for this, the utility model provides a motor assembly, its magnetic property is high, can effectively improve the power density, satisfies the use requirement.

[0004] The utility model also provides a water pump and water heater with the motor assembly.

[0005] According to the motor assembly of the first aspect embodiment of the utility model, including stator, including stator core, the stator core is annular and is equipped with inner hole;

[0006] Rotor, rotation is established in the inner hole, the rotor includes magnetic ring, the surface magnetic flux density of magnetic ring is 1700Gs to 2000Gs.

[0007] According to the motor assembly of the first aspect embodiment of the utility model, at least has following beneficial effect:

[0008] In the embodiment, by making the surface magnetic flux density of magnetic ring reach 1700Gs to 2000Gs, enhancing its magnetic property, be favorable to improving the power density of motor assembly, can adapt the application environment of high performance requirement.

[0009] According to the embodiment of the first aspect of the utility model, the minimum inner diameter of the stator core is D1, the maximum outer diameter of the magnetic ring is D3, satisfy: 0.04≤ (D1-D3) / (2*D1) ≤0.06.

[0010] According to some embodiments of the utility model, the minimum inner diameter of the stator core is D1, the maximum outer diameter of the stator core is D2, satisfy: 1.6≤D2 / D1≤2.

[0011] According to the embodiment of the first aspect of the utility model, the minimum inner diameter of the stator core is D1, along the radial direction of the stator core, the maximum thickness of the magnetic ring is T, satisfy: 0.16≤T / D1≤0.2.

[0012] According to the embodiment of the first aspect of the present application, the stator core comprises a yoke portion and a plurality of tooth portions, the plurality of tooth portions are connected to the inner wall of the yoke portion and are arranged in intervals along the direction surrounding the rotor, the tooth width of the tooth portion is W1, the minimum inner diameter of the stator core is D1, and the following condition is satisfied: 0.07≤W1 / D1≤0.11.

[0013] According to the embodiment of the first aspect of the present application, the minimum inner diameter of the stator core is D1, the stator core comprises a yoke portion and a plurality of tooth portions, the plurality of tooth portions are connected to the inner wall of the yoke portion and are arranged in intervals along the direction surrounding the rotor, along the radial direction of the stator core, the minimum width of the yoke portion is W2, and the following condition is satisfied: 0.09≤W2 / D1≤0.15.

[0014] According to the embodiment of the first aspect of the present application, the minimum inner diameter of the stator core is D1, the stator core comprises a yoke portion and a plurality of tooth portions, the plurality of tooth portions are connected to the inner wall of the yoke portion and are arranged in intervals along the direction surrounding the rotor, the slot is defined between the ends of the two adjacent tooth portions away from the yoke portion, the width of the slot is W3, and the following condition is satisfied: 0.07≤W3 / D1≤0.11.

[0015] According to the embodiment of the first aspect of the present application, the magnetic ring comprises a plurality of annular portions, and the plurality of annular portions are sequentially spliced along the axial direction of the stator core.

[0016] According to the embodiment of the first aspect of the present application, the magnetic ring is configured as a sintered ferrite magnet.

[0017] The water pump according to the embodiment of the second aspect of the present application comprises the motor assembly according to the embodiment of the first aspect of the present application.

[0018] The water pump according to the embodiment of the second aspect of the present application has at least the following beneficial effects:

[0019] In the embodiment, the water pump comprises the motor assembly, so that the surface magnetic flux density of the magnetic ring reaches 1700Gs to 2000Gs, the magnetic performance is enhanced, the power density of the motor assembly is improved, the application environment with high performance requirements can be adapted, and thus the performance of the water pump is improved.

[0020] According to the embodiment of the second aspect of the present application, the water pump comprises an impeller, the inner peripheral wall of the magnetic ring is provided with a plurality of recesses, the plurality of recesses are arranged in intervals along the circumferential direction of the magnetic ring, and the recesses are embedded and matched with the impeller.

[0021] The water heater according to the embodiment of the third aspect of the present application comprises the water pump according to the embodiment of the second aspect of the present application.

[0022] According to the third aspect of the utility model, the water heater has at least the following beneficial effects:

[0023] In the embodiment, the water pump of the water heater comprises a motor assembly, the surface magnetic flux density of the magnetic ring reaches 1700Gs to 2000Gs, the magnetic performance is enhanced, the power density of the motor assembly is improved, the application environment with high performance requirement can be adapted, and thus the performance of the water heater is improved.

[0024] The additional aspects and advantages of the utility model will be partially given in the following description, partially will become obvious from the following description, or will be understood through the practice of the utility model. BRIEF DESCRIPTION OF DRAWINGS

[0025] The utility model will be further explained in combination with the drawings and embodiments, wherein:

[0026] Figure 1 is the front view of the motor assembly in some embodiments of the utility model;

[0027] Figure 2 is Figure 1 the enlarged view of A in the figure;

[0028] Figure 3 is the sectional view of the magnetic ring in some embodiments of the utility model;

[0029] Figure 4 is the sectional view of the magnetic ring in some other embodiments of the utility model;

[0030] Figure 5 is the torque diagram of the motor of the prior art adopting plastic magnetic ferrite magnet under preset current value;

[0031] Figure 6 is the torque diagram of the motor of the embodiment of the utility model adopting sintered ferrite magnet under preset current value.

[0032] REFERENCE NUMERALS:

[0033] Stator core 100; air gap 101; yoke part 102; tooth part 103; slot 104; winding slot 105; boot part 106;

[0034] Rotor 110; magnetic ring 111; recess 112; annular part 113. DETAILED DESCRIPTION

[0035] The embodiments of the present application are described below in detail, examples of the embodiments are shown in the drawings, wherein the same or similar notations represent the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary, only for explaining the present application, and cannot be understood as a limitation of the present application.

[0036] In the description of the present application, it should be understood that, in relation to the orientation description, for example, the orientation or position relationship indicated by up, down, front, back, left, right, etc. is based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element indicated must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present application.

[0037] In the description of the present application, the meaning of several is one or more, the meaning of multiple is more than two, greater than, less than, more than, etc. are understood as not including the number, above, below, etc. are understood as including the number. If it is described as first, second, it is only for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features or the order of indicated technical features.

[0038] In the description of the present application, unless otherwise explicitly limited, the words such as setting, installing, connecting, assembling, cooperating, etc. should be broadly understood, and the person skilled in the art can reasonably determine the specific meaning of the above words in the present application in combination with the specific content of the technical scheme.

[0039] In the related art, the water pump of the water heater uses a motor assembly as a power source, wherein the rotor of the motor assembly is usually in a water environment. In the related art, the magnet of the rotor generally uses plastic ferrite, which is composed of resin and ferrite powder. The magnetic performance of the plastic ferrite is low, and it is not suitable for high-performance motors. Some magnets of the rotor use neodymium iron boron magnets, however, in the working environment with water, the neodymium iron boron magnet is prone to rust, and it is necessary to set secondary protection for the neodymium iron boron magnet, and the cost of the neodymium iron boron magnet is high.

[0040] In order to solve the above problems, with reference to Figure 1 and Figure 3 The present application provides a motor assembly in the first aspect of the embodiment, which comprises a stator and a rotor 110, the stator comprises a stator core 100, the stator core 100 is annular and provided with an inner hole, the rotor 110 is rotatably arranged in the inner hole, and the rotor 110 comprises a magnetic ring 111.

[0041] Specifically, a plurality of tooth portions 103 are arranged in the circumferential direction of the stator core 100, and a winding slot 105 is defined between two adjacent tooth portions 103. It can be understood that the motor assembly in the embodiment is applied to a three-phase permanent magnet synchronous motor, and thus the number of winding slots 105 is 3 or a multiple of 3.

[0042] It can be understood that the stator core 100 includes a yoke portion 102, and a plurality of tooth portions 103 are connected to the inner wall of the yoke portion 102 and are arranged in the direction around the rotor 110, and the tooth portions 103 extend in the radial direction of the stator core 100 from the yoke portion 102 to the rotor 110.

[0043] It can be understood that a slot 104 is defined between the ends of two adjacent tooth portions 103 away from the yoke portion 102. Further, the end of the tooth portion 103 away from the yoke portion 102 has a shoe portion 106 extending in the circumferential direction of the stator core 100 to both sides from the tooth portion 103, and the slot 104 is defined between two adjacent shoe portions 106.

[0044] It can be understood that the surface magnetic flux density of the magnetic ring 111 ranges from 1700Gs to 2000Gs, for example, the surface magnetic flux density of the magnetic ring 111 is 1750Gs, 1800Gs, 1820Gs, 1850Gs or 1900Gs, etc. Making the surface magnetic flux density of the magnetic ring reach 1700Gs to 2000Gs is conducive to improving the power density of the motor assembly, thereby adapting to the application environment with high performance requirements.

[0045] It can be understood that the magnetic ring 111 is configured as a sintered ferrite magnet, and the internal structure of the sintered ferrite magnet is compact, having high magnetic permeability and saturation magnetization. On the one hand, the magnetic performance of the sintered ferrite is better than that of the plastic magnet ferrite, so as to achieve the surface magnetic flux density of the magnetic ring 111 reaching 1700Gs to 2000Gs; on the other hand, the sintered ferrite has good corrosion resistance, and the magnetic ring 111 does not need secondary protection to adapt to the working environment with water, which is conducive to reducing the manufacturing cost.

[0046] It can be easily understood that the surface magnetic flux density of the magnetic ring 111 refers to the magnetic induction intensity of a certain point on the surface of the magnetic ring 111, and the surface magnetic flux density is an important parameter for measuring the surface magnetic field intensity of the magnetic ring 111. The surface magnetic flux density can be directly measured by a gauss meter.

[0047] Specifically, referring to Figure 5 and Figure 6 , the finite element electromagnetic simulation method is used to simulate and compare the motor using sintered ferrite magnet and the motor using plastic magnet ferrite magnet. In order to ensure the accuracy of the simulation results, the same wire gauge and number of turns and the same current are used for the two motors with different materials to compare the torque values.

[0048] It can be understood that the motor parameters of the sintered ferrite magnet are as follows: the inner diameter of the sintered ferrite magnet is 14.5 mm, the outer diameter is 24.4 mm, and the axial length is 22 mm; the inner diameter of the stator core 100 is 27.2 mm, the outer diameter is 50 mm, and the axial length is 16 mm. The motor using plastic magnetic ferrite magnet: except that the magnet is a plastic magnetic ferrite, the rest of the parameters are the same as those of the motor using sintered ferrite magnet.

[0049] It can be understood that, Figure 5 the torque diagram of the motor using the plastic magnetic ferrite magnet under the preset current value, Figure 6 the torque diagram of the motor using the sintered ferrite magnet under the same preset current value. It can be understood that when the rotational speed is constant, the average value of the peak torque of the motor using the plastic magnetic ferrite magnet is 71.4 mN.m, and the average value of the peak torque of the motor using the sintered ferrite magnet is 85.2 mN.m. Therefore, compared with the motor using the plastic magnetic ferrite magnet, the average value of the peak torque of the motor using the sintered ferrite magnet is increased by 19%, and the power is increased by 19%. It can be understood that under the condition that the volume of the magnet is the same, the magnet using the sintered ferrite can increase the power density by 19%, thereby improving the performance of the motor. Or it can be understood that under the condition of achieving the same power density, the magnet using the sintered ferrite can reduce the volume by 19%, which can reduce the volume and cost while optimizing the installation of the motor.

[0050] Referring to Figure 4 In some other embodiments, it can be understood that the magnetic ring 111 includes a plurality of annular portions 113 which are sequentially spliced along the axial direction of the stator core 100. It can be understood that for a motor with higher performance, the axial length of the magnetic ring 111 is larger, and the machining difficulty is larger under the premise of ensuring accuracy, so that the plurality of annular portions 113 spliced along the axial direction of the stator core 100 can reduce the machining difficulty and improve the machining effect and ensure the accuracy of the magnetic ring 111.

[0051] Referring to Figure 1 and Figure 3 It can be understood that the inner peripheral wall of the magnetic ring 111 is provided with a plurality of recesses 112 which are arranged at intervals along the circumferential direction of the magnetic ring 111, and the recesses 112 are used for embedding cooperation with the impeller. It can be understood that the impeller is made of plastic material, and the impeller and the magnetic ring 111 are combined and formed by injection molding.

[0052] Specifically, the impeller is provided with a rotating shaft, and a plurality of protrusions are arranged on the rotating shaft and embedded in the recesses 112 to position the magnetic ring 111 and the rotating shaft along the circumferential direction of the stator core 100, and the protrusions and the recesses 112 are buckled to enable the magnetic ring 111 to rotate synchronously with the impeller. Moreover, the buckling of the protrusions and the recesses 112 can increase the contact area of the impeller and the magnetic ring 111, thereby improving the connection strength and ensuring the working stability of the motor.

[0053] It can be understood that the recess 112 extends along the axial direction of the magnetic ring 111, and the recess 112 is arranged at one end of the magnetic ring 111. On the premise of achieving torque transmission from the impeller to the magnetic ring 111, the thickness of the magnetic ring 111 is not excessively reduced, and the magnetic ring 111 has sufficient thickness, thereby avoiding demagnetization caused by large temperature rise during heavy load operation, and ensuring the performance of the motor.

[0054] It can be understood that the recess 112 is arranged at both axial ends of the magnetic ring 111, and the recess 112 extends inward from the end wall of both ends of the magnetic ring 111 along the axial direction of the magnetic ring 111 to a predetermined depth, which is beneficial to improve the connection stability of the magnetic ring 111 and the rotating shaft, thereby facilitating the transmission of torque from the rotor 110 to the impeller.

[0055] In some embodiments, the recess 112 is arranged at any one end of the magnetic ring 111, and the recess 112 extends inward from the end wall of any one end of the magnetic ring 111 along the axial direction of the magnetic ring 111 to a predetermined depth. Only one end of the magnetic ring 111 needs to be machined during processing, which is beneficial to simplify the processing steps and improve the processing efficiency.

[0056] In some embodiments, the recess 112 extends along the axial direction of the magnetic ring 111, and the recess 112 penetrates through both axial ends of the magnetic ring 111, which is beneficial to simplify the structure, thereby simplifying the processing steps, improving the processing efficiency, and increasing the contact area of the magnetic ring 111 and the impeller, thereby improving the bonding strength of the magnetic ring 111 and the impeller and ensuring the working stability of the motor.

[0057] Referring to Figure 1 It can be understood that the minimum inner diameter of the stator core 100 is defined as D1, and the maximum outer diameter of the magnetic ring 111 is defined as D3, and the following condition is satisfied: 0.04≤(D1-D3) / (2*D1)≤0.06.

[0058] It can be understood that, along the radial direction of the stator core 100, twice the shortest distance of the stator core 100 from the central axis is the minimum inner diameter D1 of the stator core 100.

[0059] Specifically, referring to Figure 1 and Figure 2For the inner rotor motor, the inner circumferential wall of the stator core 100 and the outer circumferential wall of the magnetic ring 111 have the air gap 101 therebetween, and the minimum width of the air gap 101 along the radial direction of the stator core 100 is defined as W4, and it can be understood that half of the difference between the minimum inner diameter D1 of the stator core 100 and the maximum outer diameter D3 of the magnetic ring 111 is the minimum width W4 of the air gap 101 along the radial direction of the stator core 100, W4=(D1-D3) / 2. Further, (D1-D3) / (2*D1)=W4 / D1. Therefore, the relationship between the minimum inner diameter D1 of the stator core 100 and the maximum outer diameter D3 of the magnetic ring 111, (D1-D3) / (2*D1), is the ratio of the minimum width W4 of the air gap 101 to the minimum inner diameter D1 of the stator core 100.

[0060] In the present embodiment, the ratio of the minimum width W4 of the air gap 101 to the minimum inner diameter D1 of the stator core 100 is between 0.04 and 0.06. For example, the ratio of the minimum width W4 of the air gap 101 to the minimum inner diameter D1 of the stator core 100 is 0.04, 0.05 or 0.06.

[0061] It can be understood that when the minimum width W4 of the air gap 101 to the minimum inner diameter D1 of the stator core 100 is below 0.04, the distance between the outer circumferential wall of the magnetic ring 111 and the inner circumferential wall of the stator core 100 is too small, which will cause the shield sleeve installed between the magnetic ring 111 and the stator core 100 to rub against the magnetic ring 111 when rotating. At the same time, since water will enter the gap between the magnetic ring 111 and the shield sleeve when the water pump is working, impurities in the water will easily block the gap between the shield sleeve and the magnetic ring 111, thus easily causing the phenomenon of locked rotor. When the minimum width W4 of the air gap 101 to the minimum inner diameter D1 of the stator core 100 is above 0.06, the distance between the outer circumferential wall of the magnetic ring 111 and the inner circumferential wall of the stator core 100 is too large, the magnetic flux density at the air gap 101 is too small, the magnetic resistance is too large, and the back electromotive force is small, thus causing the performance of the motor to decrease. Therefore, the relationship between the minimum inner diameter D1 of the stator core 100 and the maximum outer diameter D3 of the magnetic ring 111 is made to satisfy: 0.04≤(D1-D3) / (2*D1)≤0.06, so that the width of the air gap 101 along the radial direction of the stator core 100 is within an appropriate range of values, the locked rotor can be avoided, the magnetic flux density can be improved, and the motor can have good performance.

[0062] Referring to Figure 1It can be understood that the minimum inner diameter of the stator core 100 is D1, and the maximum outer diameter of the stator core 100 is D2, which satisfies: 1.6≤D2 / D1≤2. It can be understood that the ratio between the maximum outer diameter D2 of the stator core 100 and the minimum inner diameter D1 of the stator core 100 can be 1.6, 1.7, 1.8, 1.9 or 2.

[0063] It can be understood that when the minimum inner diameter D1 of the stator core 100 is constant, if the ratio between the maximum outer diameter D2 of the stator core 100 and the minimum inner diameter D1 of the stator core 100 is less than 1.6, and the width of the yoke portion 102 is constant, then the winding slot 105 along the radial dimension of the stator core 100 will be too small, and the area of the winding slot 105 will be too small, which will result in a decrease in the slot fill rate, thereby reducing the performance of the motor. On the other hand, when the minimum inner diameter D1 of the stator core 100 is constant, if the ratio between the maximum outer diameter D2 of the stator core 100 and the minimum inner diameter D1 of the stator core 100 is greater than 2.0, then the outer diameter dimension of the motor will increase, which is not conducive to the installation of the motor, and the amount of material will increase, thereby increasing the cost. Therefore, when the ratio between the maximum outer diameter D2 of the stator core 100 and the minimum inner diameter D1 of the stator core 100 is 1.6 to 2, the stator core 100 can maintain a compact size while improving the slot fill rate, thereby making the motor meet the performance requirements.

[0064] Referring to Figure 1 It can be understood that the minimum inner diameter of the stator core 100 is D1, and the maximum thickness of the magnetic ring 111 along the radial direction of the stator core 100 is T, which satisfies: 0.16≤T / D1≤0.2. It can be understood that the ratio between the maximum thickness T of the magnetic ring 111 and the minimum inner diameter D1 of the stator core 100 can be 0.16, 0.17, 0.18, 0.19 or 0.2.

[0065] It can be understood that the maximum thickness T of the magnetic ring 111 is the maximum distance between the inner circumferential wall and the outer circumferential wall of the magnetic ring 111 in the radial direction of the stator core 100.

[0066] It can be understood that, when the minimum inner diameter D1 of the stator core 100 is constant, if the ratio between the maximum thickness T of the magnetic ring 111 and the minimum inner diameter D1 of the stator core 100 is less than 0.16, the thickness of the magnetic ring 111 is too small, and the motor is prone to have a rapid temperature rise when operating under a large load. The temperature of the magnetic ring 111 with the small thickness is transferred too fast, which is prone to cause demagnetization of the magnetic ring 111, thereby causing operation failure. When the minimum inner diameter D1 of the stator core 100 is constant, if the ratio between the maximum thickness T of the magnetic ring 111 and the minimum inner diameter D1 of the stator core 100 is greater than 2, the thickness of the magnetic ring 111 is too large, and the use of the material is too much, thereby causing an increase in cost. Therefore, when the minimum inner diameter D1 of the stator core 100 and the maximum thickness T of the magnetic ring 111 satisfy 0.16≤T / D1≤0.2, the material usage can be optimized under the premise of avoiding a too large temperature rise that is prone to cause demagnetization, thereby helping to ensure the performance of the motor and save cost.

[0067] With reference to Figure 1 It can be understood that the tooth width of the tooth portion 103 is defined as W1, and the minimum inner diameter of the stator core 100 is D1, and 0.07≤W1 / D1≤0.11 is satisfied. It can be understood that the ratio between the tooth width W1 of the tooth portion 103 and the minimum inner diameter D1 of the stator core 100 can be 0.08, 0.09, 0.1, or 0.11.

[0068] It can be understood that, along the circumferential direction of the stator core 100, the distance between the two opposite wall surfaces of the tooth portion 103 is the tooth width W1 of the tooth portion 103.

[0069] It can be understood that, when the minimum inner diameter D1 of the stator core 100 is constant, if the ratio between the tooth width W1 of the tooth portion 103 and the minimum inner diameter D1 of the stator core 100 is less than 0.07, the thickness of the tooth portion 103 is too small, the magnetic flux density of the tooth portion 103 is increased, thereby increasing the magnetic saturation degree of the stator core 100, increasing the iron loss, and reducing the efficiency of the motor. At the same time, the strength of the tooth portion 103 is weakened, thereby causing the strength of the stator core 100 to be poor, and vibration and noise are prone to occur during operation. On the other hand, when the minimum inner diameter D1 of the stator core 100 is constant, if the ratio between the tooth width W1 of the tooth portion 103 and the minimum inner diameter D1 of the stator core 100 is greater than 0.11, the thickness of the tooth portion 103 is too large, thereby reducing the size of the winding slot 105, causing the slot fill rate to be reduced, and increasing the copper loss of the motor. Although the increase in the tooth width reduces the iron loss of the motor, the total loss is increased, thereby reducing the efficiency of the motor. Therefore, when the tooth width W1 of the tooth portion 103 and the minimum inner diameter D1 of the stator core 100 satisfy 0.07≤W1 / D1≤0.11, the motor can have a small loss, and the stator core 100 can have sufficient strength to avoid vibration and noise, thereby ensuring good performance of the motor.

[0070] With reference to Figure 1 It can be understood that, along the radial direction of the stator core 100, the minimum width of the yoke portion 102 is defined as W2, and the minimum inner diameter D1 of the stator core 100 and the minimum width W2 of the yoke portion 102 satisfy: 0.09≤W2 / D1≤0.15. It can be understood that the ratio between the minimum width W2 of the yoke portion 102 and the minimum inner diameter D1 of the stator core 100 can be 0.09, 0.1, 0.11, 0.12, 0.13, 0.14 or 0.15.

[0071] It can be understood that the minimum width W2 of the yoke portion 102 is the minimum distance between the outer peripheral wall of the stator core 100 and the wall surface of the wire slot 105 farthest from the central axis of the stator core 100 in the radial direction of the stator core 100.

[0072] It can be understood that, when the minimum inner diameter D1 of the stator core 100 is constant, if the ratio between the minimum width W2 of the yoke portion 102 and the minimum inner diameter D1 of the stator core 100 is less than 0.09, the width of the yoke portion 102 will be too small, the magnetic flux density of the yoke portion 102 will be too large, the degree of magnetic saturation will increase, and the iron loss will increase. At the same time, the strength of the yoke portion 102 will be weakened, and vibration and noise are likely to occur during operation. When the minimum inner diameter D1 of the stator core 100 is constant, if the ratio between the minimum width W2 of the yoke portion 102 and the minimum inner diameter D1 of the stator core 100 is greater than 0.15, the outer diameter size of the stator core 100 will be too large, which is not conducive to the installation of the motor, and the amount of material of the stator core 100 will increase, which will cause the cost to rise. Furthermore, when the maximum outer diameter D2 of the stator core 100 is constant, if the ratio between the minimum width W2 of the yoke portion 102 and the minimum inner diameter D1 of the stator core 100 is greater than 0.15, the size of the wire slot 105 will be too small, which will result in a decrease in slot fill rate, and thus an increase in copper loss of the motor. Therefore, when the ratio between the minimum width W2 of the yoke portion 102 and the minimum inner diameter D1 of the stator core 100 satisfies: 0.09≤W2 / D1≤0.15, the motor can have a smaller loss, the stator core 100 can have a good structural strength to reduce vibration and noise, and the motor can have a good performance.

[0073] With reference to Figure 1 It can be understood that the width of the slot opening 104 is defined as W3, and satisfies: 0.07≤W3 / D1≤0.11. It can be understood that the ratio between the width W3 of the slot opening 104 and the minimum inner diameter D1 of the stator core 100 can be 0.07, 0.08, 0.09, 0.1 or 0.11. The width W3 of the slot opening 104 is the distance between the two adjacent shoe portions 106.

[0074] It can be understood that, when the minimum inner diameter D1 of the stator core 100 is constant, the ratio of the width W3 of the slot opening 104 to the minimum inner diameter D1 of the stator core 100 is less than 0.07, that is, the width of the slot opening 104 is too small, and due to the current needle inner winding winding process, the width of the slot opening 104 is too small, which will increase the winding difficulty, thereby reducing the processing efficiency. On the other hand, when the minimum inner diameter D1 of the stator core 100 is constant, the ratio of the width W3 of the slot opening 104 to the minimum inner diameter D1 of the stator core 100 is greater than 0.11, that is, the width of the slot opening 104 is too large, which will cause the tooth slot torque to be large, thereby increasing the torque ripple of the motor, and the vibration and noise during operation will increase. And the position accuracy of the rotor 110 will be reduced, thereby causing the control accuracy of the motor to decrease. Therefore, when the ratio of the width W3 of the slot opening 104 to the minimum inner diameter D1 of the stator core 100 satisfies 0.07≤W3 / D1≤0.11, both easy processing and good running stability and control accuracy of the motor can be ensured.

[0075] The water pump according to the second aspect of the present application comprises the motor assembly according to the first aspect of the present application.

[0076] The water pump adopts all the technical solutions of the motor assembly according to the above embodiments, and thus at least has all the beneficial effects brought by the technical solutions of the above embodiments.

[0077] The water heater according to the third aspect of the present application comprises the water pump according to the second aspect of the present application.

[0078] The water heater adopts all the technical solutions of the water pump according to the above embodiments, and thus at least has all the beneficial effects brought by the technical solutions of the above embodiments.

[0079] The embodiments of the present application are described in detail above in combination with the drawings, but the present application is not limited to the above embodiments, and various changes can be made within the knowledge of those skilled in the art without departing from the spirit of the present application.

Claims

1. An electric machine assembly, characterized by The motor assembly comprises: a stator comprising a stator core, the stator core being annular and provided with an inner hole; a rotor rotatably arranged in the inner hole, the rotor comprising a magnetic ring, a surface magnetic flux density of the magnetic ring being in a range of 1700Gs to 2000Gs.

2. The electric machine assembly of claim 1, wherein: A minimum inner diameter of the stator core is D1, a maximum outer diameter of the magnetic ring is D3, and the following condition is satisfied: 0.04≤(D1-D3) / (2*D1)≤0.

06.

3. The electric machine assembly of claim 1, wherein: A minimum inner diameter of the stator core is D1, a maximum outer diameter of the stator core is D2, and the following condition is satisfied: 1.6≤D2 / D1≤2.

4. The electric machine assembly of claim 1, wherein: A minimum inner diameter of the stator core is D1, and a maximum thickness of the magnetic ring along a radial direction of the stator core is T, and the following condition is satisfied: 0.16≤T / D1≤0.

2.

5. The electric machine assembly of claim 1, wherein: The stator core comprises a yoke portion and a plurality of tooth portions, the plurality of tooth portions being connected to an inner wall of the yoke portion and being arranged at intervals in a direction surrounding the rotor, a tooth width of the tooth portion is W1, a minimum inner diameter of the stator core is D1, and the following condition is satisfied: 0.07≤W1 / D1≤0.

11.

6. The electric machine assembly of claim 1, wherein: The stator core comprises a yoke portion and a plurality of tooth portions, the plurality of tooth portions being connected to an inner wall of the yoke portion and being arranged at intervals in a direction surrounding the rotor, a minimum width of the yoke portion along a radial direction of the stator core is W2, and the following condition is satisfied: 0.09≤W2 / D1≤0.

15.

7. The electric machine assembly of claim 1, wherein: The stator core comprises a yoke portion and a plurality of tooth portions, the plurality of tooth portions being connected to an inner wall of the yoke portion and being arranged at intervals in a direction surrounding the rotor, a notch is defined between one end of two adjacent tooth portions away from the yoke portion, a width of the notch is W3, and the following condition is satisfied: 0.07≤W3 / D1≤0.

11.

8. The electric machine assembly of claim 1, wherein: The magnetic ring comprises a plurality of annular portions, the plurality of annular portions being sequentially spliced in an axial direction of the stator core.

9. The electric machine assembly of claim 1, wherein: The magnetic ring is configured as a sintered ferrite magnet.

10. A water pump characterized by The motor assembly comprises any one of claims 1 to 9.

11. The water pump of claim 10, wherein: The water pump comprises an impeller, an inner peripheral wall of the magnetic ring is provided with a plurality of recesses, the plurality of recesses being arranged at intervals in a circumferential direction of the magnetic ring, and the recesses are embeddedly matched with the impeller.

12. A water heater characterised by The water pump comprises any one of claims 10 or 11.

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