Food processor

Abstract

The utility model relates to a food processor which comprises a variable frequency motor, and the variable frequency motor comprises a motor shell which is provided with a cavity; the stator assembly is mounted in the cavity; the rotor assembly is arranged in the stator assembly and comprises a rotor iron core, a plurality of magnetic steels embedded in the rotor iron core and a rotor shaft arranged in the rotor iron core in a penetrating manner, a plurality of pole teeth are arranged on the periphery of the rotor iron core in an outward protruding manner, and a tooth groove is formed between every two adjacent pole teeth; the pole teeth and the magnetic steels are arranged in a one-to-one correspondence manner; wherein the distance between the tooth tops of the pole teeth and the center of the rotor iron core is R, the R is larger than or equal to 8 and smaller than or equal to 17 mm, the distance between the groove bottoms of the tooth grooves and the center of the rotor iron core is r, and the ratio of r to R is 0.84-0.92. The small variable frequency motor is adopted in the food processor, and the requirements for low motor noise and high motor output torque are met at the same time.

Description

TECHNICAL FIELD

[0001] The utility model relates to food processing machine technical field especially, it is a kind of food processing machine of low noise high torque. BACKGROUND

[0002] With the development of food processing machine, people gradually begin to pursue higher quality use experience, and traditional food processing machine is generally driven by series motor based on product pricing limit and simple driving demand, but series motor has many problems, such as motor transmission efficiency fluctuation is larger, axial flow heat dissipation efficiency is low, machine base volume is large, noise is obvious, etc., in order to solve the above problems, gradually break the conventional technical concept, begin to use brushless motor. Brushless motor includes rotor and stator, rotor includes rotor core and magnet embedded in rotor core.

[0003] In prior art, it is applied more on miniaturized food processing machine. For example, the application number CN202021074206.6, the invention name "a juicer", discloses that the cup cover top cover and cup cover base are combined to form an inner cavity, the direct-current brushless outer rotor motor is fixedly installed in the inner cavity, and the motor shaft of the direct-current brushless outer rotor motor passes through the shaft hole and is threadedly connected with the cutter head. At the same time, the applicant's prior application number CN202021171400.6, the invention name "a motor assembly of food processing machine and food processing machine with ultra-thin main machine", also discloses that the brushless motor is arranged on the portable food processing machine, the motor body, the control panel assembly and the battery assembly are arranged in the axial direction, and the control panel assembly is attached to the axial end of the motor body. On the basis of using the flat brushless motor, the control panel assembly is attached to the axial end of the motor body, so as to further compress the space in the axial direction of the main machine. The foregoing prior art applies brushless motor on miniaturized food processing machine. Compared with ordinary brush motor (such as series motor), the overall volume of the motor can be reduced, that is, the motor is a small volume motor with reduced radial and axial dimensions. The technical problem existing in the above technical scheme is that although the small volume brushless motor is used in the portable food processing machine (such as a juicer), the overall volume of the machine is smaller; but the portable food processing machine is generally used for crushing soft food materials to extract cold fruit juice, and the requirement for motor output torque is low, and the noise is small accordingly. However, the portable juicer is also one of its functions to crush hard materials at high speed, and users will use this function in a few cases, so when crushing hard materials at high speed (for example, crushing ice), the low-torque small motor obviously cannot meet the performance requirements of the product itself, and it is difficult to process food materials with high output torque requirements.

[0004] In the ordinary food processor, there are also more brushless motor applications, for example, the applicant's prior application number CN202120349580.0, the invention name is "a stable food processor", the specific scheme of the rotor in the brushless motor is: the rotor core is provided with a magnetic tile mounting groove, the magnetic tile is inserted into the magnetic tile mounting groove along the axial direction, the end plate is pressed against the end face of the magnetic tile and the end face of the rotor core, the magnetic tile mounting groove has six segments, the six segments extend along the circumference of the rotor core and are arranged at intervals. The applicant's application number CN202322212945.7, the invention name is "a connected stable permanent magnet DC brushless motor", also discloses that the outer edge of the rotor core is provided with a mounting groove, the permanent magnet is arranged in the mounting groove, the mounting groove and the permanent magnet are arranged as an even number, according to the drawing, the permanent magnet is provided with six, the six permanent magnets are arranged in sequence along the circumference of the rotor core. The foregoing two prior arts use rotor cores with six permanent magnets on ordinary food processors, when the demand for output torque increases, six permanent magnets are set, the effective use area is relatively small, so that the generated magnetic flux is small, and then the output torque is small, obviously it is difficult to meet the demand of larger output torque. Therefore, the application number CN202420158859.4, the invention name is "a permanent magnet synchronous motor rotor structure", also discloses that the rotor core is provided with eight magnetic steel groove groups along the circumference, each magnetic steel groove group includes two magnetic steel grooves arranged in V shape, the magnetic steel groove is used for installing permanent magnet steel, a total of sixteen permanent magnet steels are installed. The technical problem existing in the above technical scheme is: although sixteen permanent magnet steels are set, more magnetic steels are used to meet the demand of larger output torque, but under the condition that the outer diameter of the rotor core is the same, the more the number of magnetic steel mounting grooves, the length of the single magnetic steel mounting groove will be correspondingly reduced, and the smaller the magnetic steel mounting groove, the more difficult the processing.

[0005] Based on the foregoing two prior arts, both are brushless motor applied to ordinary food processor, and the ordinary food processor generally has a larger volume. Correspondingly, in order to meet the output torque demand of the ordinary food processor, a brushless motor with a large outer diameter is required to drive, that is, a large outer diameter rotor core. When the motor outer diameter is not changed, in order to increase the output torque, more magnetic steel grooves are arranged in the large outer diameter rotor core, and the manufacturing difficulty is greater. It can be understood that in order to have a large output torque, a small motor has more magnetic steel grooves arranged in a small and miniaturized rotor core with a small outer diameter, which will be more difficult to manufacture and process than a large outer diameter rotor core. The miniaturized rotor core cannot be directly scaled down in proportion to a large motor, not only the processing difficulty is great, but also the contradiction between output torque and noise needs to be considered. Specifically, the number of magnetic steels on the rotor core increases, which is easy to cause high-frequency noise, thereby causing greater processing noise; when using a large wall breaking machine (large motor), the user may have greater tolerance for the noise of the large wall breaking machine; when used in a small outer diameter motor, the user has more stringent requirements for noise, and if a large noise is brought, the user experience performance cannot be met. However, reducing the number of magnetic steels may also result in a decrease in the number of magnetic steels that can be effectively used, thereby reducing the output torque and making it difficult to meet the performance requirements of the product itself.

[0006] In order to solve the problem of large number of magnetic shoe installation slots and difficult processing, the application number CN201810186164.6, the invention name "food processor and its speed increasing control method and device", discloses a driving motor including a stator core and a rotor core, the rotor core is arranged in the stator hole inside the stator core, the rotor core is provided with four magnetic body grooves, the permanent magnet is provided with four, each permanent magnet is inserted in the corresponding magnetic body groove. The outer periphery of the rotor core is outwardly provided with a plurality of pole teeth, a tooth slot is formed between adjacent two pole teeth, the center of the rotor core is a circle center and the radius of the circle tangent to the tooth top of the pole tooth is R, the radius of the circle tangent to the slot bottom of the tooth slot and taking the center of the rotor core as the circle center is r, r: R = 0.96-0.98. The technical scheme is applied to an ordinary food processor, only four magnetic body grooves are arranged on the rotor core, and the number of four permanent magnets is less than that of six and sixteen magnetic body grooves in the foregoing scheme, which reduces the processing difficulty of the magnetic body groove, and the ratio of the radius of the tooth slot bottom to the radius of the tooth top is controlled to reduce the tooth slot effect and reduce the noise interference, while ensuring the efficiency of the rotor core.

[0007] However, the technical problems existing in the technical scheme are that: the application sets the tooth groove, and sets the range of r:R=0.96-0.98, which only reduces the tooth groove effect and reduces the noise interference compared with the full circular rotor. Moreover, the application is applied to the ordinary food processor (large motor), and the user has greater tolerance for the noise of the ordinary food processor, so that the adverse factors of the increased motor noise can be weakened. It can be understood that when R is constant, the larger r:R, even reaching r:R=0.96-0.98 of the application, that is, the tooth groove is shallower, that is, the outer circle of the rotor core is rounder, the air gap between the motor stator and the rotor tends to be uniform, the air gap magnetic density distribution under the magnet will be closer to the trapezoidal wave, and there are more harmonics, so that the tooth groove torque becomes larger, the increase of the tooth groove torque aggravates the amplitude of the motor electromagnetic noise, and the torque pulsation of the brushless motor is caused, and then the speed fluctuation is caused. When the frequency of the pulsating torque is consistent with the armature current resonance frequency, resonance occurs, the noise increases sharply, and the overall noise of the motor increases. On the other hand, in order to solve the problem of the large motor noise caused by the large tooth groove torque due to the large r:R ratio, the r:R ratio is reduced; at this time, the tooth groove is deeper, which will cause the overall efficiency of the motor to be reduced, and the power density and the output torque of the motor will also be reduced. Since the brushless motor in the technical scheme is used in the ordinary multifunctional food processor, the brushless motor of the food processor is generally large, if the output torque of the motor is reduced, the design requirements of the minimum output torque of the food processor may not be met, the crushing performance of the food processor will be difficult to guarantee, and the problems of low crushing efficiency and incomplete crushing may occur. Obviously, in the process of realizing the large output torque, it is understood that the user has great tolerance for the noise of the ordinary food processor, and the factors of weakening the increase of the motor noise. Therefore, in the ordinary food processor (large motor), there is a contradiction between the motor noise and the size of the output torque. Therefore, the existing technology has the technical contradiction that the motor noise and the size of the output torque are difficult to balance in the small-sized variable frequency motor. Practical new type content

[0008] The purpose of the present application is to provide a food processor to solve the technical contradiction that the motor noise and the size of the output torque are difficult to balance in the small-sized variable frequency motor in the food processor.

[0009] In order to solve the above technical problems, the present application provides a food processor, which comprises a variable frequency motor, wherein the variable frequency motor comprises:

[0010] A motor housing having a cavity;

[0011] A stator assembly installed in the cavity;

[0012] The rotor assembly is arranged in the stator assembly, and comprises a rotor core, a plurality of magnetic steels embedded in the rotor core, and a rotor shaft penetrating the rotor core, one end of the rotor shaft penetrating the motor shell, and a plurality of pole teeth are arranged outwardly along the outer periphery of the rotor core, and a tooth slot is formed between two adjacent pole teeth, and each pole tooth and each magnetic steel are arranged one by one.

[0013] Preferably, the distance between the tooth top of the pole tooth and the center of the rotor core is R, 8≤R≤17mm, the distance between the bottom of the tooth slot and the center of the rotor core is r, and r:R is 0.84-0.92.

[0014] Preferably, the height of the rotor core is H, the maximum radial dimension of the rotor core is D, 2R=D, D: H is 0.9-1.1, and r:R is 0.83-0.93.

[0015] Preferably, the pole teeth are provided with four, the magnetic steels are provided with four, and the line connecting the tooth top of each pole tooth and the center of the rotor core is arranged vertically with the line connecting the tooth top of the adjacent pole tooth and the center of the rotor core.

[0016] Preferably, the cross section of the rotor core along the radial direction is approximately square.

[0017] Preferably, when D: H is less than 1, the output torque of the variable frequency motor is not less than 80mN.m, and r:R is 0.84-0.93.

[0018] Preferably, when D: H is greater than 1, the output torque of the variable frequency motor is not less than 30mN.m, and r:R is 0.84-0.92.

[0019] Preferably, the motor shell has a mounting cavity accommodating a bearing, the rotor shaft penetrates the bearing, and there is a gap between the side of the bearing away from the motor shell and the end of the rotor core.

[0020] Preferably, the rotor assembly further comprises an end plate fixedly sleeved on the outer rotor shaft, the end plate is pressed to the end of the rotor core and the end of the magnetic steel, and the rotor shaft penetrates the end plate.

[0021] Preferably, the outer diameter of the end plate is smaller than the maximum outer diameter of the rotor core.

[0022] Preferably, one end of the end plate towards the rotor core has an outwardly extending step, and at least part of the step covers the magnetic steel.

[0023] Preferably, the food processor further comprises a fan sleeved and fixed outside the rotor shaft, the fan having an extension along the rotor shaft, the extension abutting an end of the end plate away from the rotor core.

[0024] Preferably, the height of the end plate is H1, the height of the rotor core is H, and H1:H is 0.075-0.4.

[0025] Preferably, a plurality of weight-reducing holes are formed through the rotor core, and the weight-reducing holes are arranged at intervals from the magnetic steel.

[0026] Preferably, the radius of the rotor shaft is R1, and R1:R is 0.19-0.5.

[0027] The food processor has the following beneficial effects:

[0028] 1. The food processor provided by the utility model is through a small motor of a small-sized rotor (8<=R<=17mm), and when the ratio of the distance (r) between the bottom of the tooth groove and the center of the rotor core and the distance (R) between the top of the pole tooth and the center of the rotor core (r:R is 0.84-0.92) is moderate, the small motor tooth groove torque can be made not too large by setting a reasonable tooth groove depth, the overall noise requirement is met, and the experience performance requirement of the user is met; in addition, the effective volume size of the rotor core is ensured, the output torque requirement of the small motor is met, the performance requirement of the product itself is met, and the technical contradiction that the motor noise and the output torque are difficult to balance can be solved. Because when r:R is very large (greater than 0.92), if the distance between the top of the pole tooth and the center of the rotor core is unchanged, the distance between the bottom of the tooth groove and the center of the rotor core is large, that is, the tooth groove is shallow, and the outer periphery of the rotor core tends to be full circle. Although the output torque requirement of the small-sized brushless motor can be met, the air gap between the motor stator and the rotor tends to be uniform, the air gap magnetic density distribution under the magnet tends to be closer to trapezoidal wave, there are more harmonics, and the tooth groove torque is large, so that the overall noise of the motor is sharply increased; in the case that the small-sized brushless motor is applied to a severe noise requirement, the experience performance requirement of the user cannot be met. When r:R is very small (less than 0.84), if the distance between the top of the pole tooth and the center of the rotor core is unchanged, the distance between the bottom of the tooth groove and the center of the rotor core is small, that is, the tooth groove is deep, the pole shape of the rotor core is more obvious, the effective volume of the rotor core is reduced, the output torque of the motor is reduced, the performance requirement of the product itself is difficult to meet; in addition, the overall noise of the motor under the processing working condition is increased, because large wind noise is easily generated, and therefore, the experience performance requirement of the user still cannot be met.

[0029] 2. When the height of the rotor core is H, the maximum radial dimension of the rotor core is D, 2R=D, D:H is 0.9-1.1, and r:R is 0.83-0.93; when D:H is 0.9-1.1, in the case of low noise and high output torque, the range of r:R that can be taken is larger, and the closer D:H is to 1, the larger the range of r:R that can be taken, so that the size of the tooth slot depth can be selected in a larger range, which is conducive to reducing the processing difficulty; it is especially conducive to processing a small rotor core, because even if a small rotor is processed into a form with a shallow tooth slot (reduced processing difficulty), it can still meet the performance requirements of high output torque and low noise.

[0030] 3. By providing four pole teeth and four magnetic steels, the line connecting the tooth top of each pole tooth and the center of the rotor core is perpendicular to the line connecting the tooth top of the adjacent pole tooth and the center of the rotor core; thereby based on only four magnetic steel grooves being provided on the rotor core and the magnetic steels being inserted into the magnetic steel grooves, since the magnetic steel grooves are processed on a miniaturized rotor, the circumferential length of the miniaturized rotor is small, and by providing a smaller number of magnetic steels, the processing difficulty of the miniaturized rotor will be greatly reduced, while not allowing the number of magnetic steels to be too small to ensure the effective volume of the rotor core, thereby ensuring that the output torque meets the needs of small motors; at the same time, the rotor core salient pole shape is more obvious, and by setting a reasonable tooth slot depth, a rotor core with a nearly square cross section is obtained, so that the tooth slot torque of the small motor is not too large, the overall noise requirement is met, and the user's experience performance requirement is met; in addition, the effective volume of the rotor core can be ensured, the output torque requirement of the small motor is met, thereby meeting the performance requirement of the product itself, and further solving the technical contradiction that the motor noise and output torque are difficult to balance.

[0031] 4. Based on when D:H is greater than 1, the maximum outer diameter D of the rotor core is greater than the height H of the rotor core, the rotor core shape is relatively flattened, the main machine is more flattened, the axial size of the whole machine is compressed, which is beneficial to improve the portability of the whole machine; and by setting a reasonable tooth groove depth (r:R is 0.84-0.92), the overall noise of the motor can be realized to be lower than 45 decibels, meeting the performance requirements of user experience; and the effective volume size of the rotor core can be ensured, meeting the output torque requirements of small motors, so that the output torque of the variable frequency motor is not less than 30 mN.m, which is the performance requirement that the portable small food processor needs to achieve. When D:H is less than 1, that is, the maximum outer diameter D of the rotor core is less than the height H of the rotor core, the rotor core shape is relatively long, the radial size of the variable frequency motor is reduced, thereby the radial size of the whole machine is reduced; and by setting a reasonable tooth groove depth, r:R is set to 0.84-0.93, the overall noise of the motor can be realized to be lower than 68 decibels; and the effective volume size of the rotor core can be ensured, meeting the output torque requirements of small motors, so that the output torque of the variable frequency motor is not less than 80 mN.m, meeting the performance requirements of food processors with higher output torque requirements, so that the small variable frequency motor has a wider application value in food processors.

[0032] 5. By installing a gap between the bearing of the rotor shaft and the end of the rotor core, the resonance caused by the contact between the two during the operation of the motor is prevented, thereby causing additional mechanical noise of the motor. On the other hand, by providing a gap between the bearing and the rotor core, that is, without any components at the upper and lower ends of the rotor core to achieve counterweight, especially for the flattened rotor core, the rotor core can still maintain a relatively small radial deviation, that is, the motor has a good dynamic balance effect. In this way, without setting the counterweight, the internal structure of the small variable frequency motor is greatly simplified, the volume of the main machine is greatly reduced, thereby facilitating the miniaturization of the whole machine, and also facilitating cost reduction.

[0033] 6. Based on the end plate fixed on the outside of the rotor shaft, the end plate is pressed against the end of the rotor core and the end of the magnetic steel, which can limit the magnetic steel from separating from the magnetic steel slot in the axial direction during the rotation of the rotor, to ensure the normal operation of the rotor core. At the same time, the end plate on the rotor shaft increases the weight of the rotor assembly during the rotation of the rotor, preventing the long rotor core from producing obvious radial shaking, to achieve the dynamic balance of the rotor assembly, thereby making the motor have a good dynamic balance effect. Furthermore, the end plate has a step extending outward towards one end of the rotor core, at least part of the step covers the magnetic steel, and the rest of the end plate can not be in contact with the rotor core or the magnetic steel, only the step of the end plate is in contact with the rotor core and the magnetic steel, which can reduce the contact area between the end plate and the rotor core, further reduce the resonance between the two, and thereby more facilitate the reduction of the motor noise under processing conditions. BRIEF DESCRIPTION OF DRAWINGS

[0034] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments recorded in this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 This is a cross-sectional schematic diagram of a food processing machine according to one embodiment of the present invention.

[0036] Figure 2 for Figure 1 The diagram shows the structure of the rotor core.

[0037] Figure 3 for Figure 2 The diagram shows a top view of the rotor core.

[0038] Figure 4 for Figure 1 The diagram shows a cross-sectional view of the motor housing, rotor assembly, and bearings.

[0039] Figure 5 This is a schematic diagram of the rotor assembly and fan in another embodiment of the present invention.

[0040] Figure 6 for Figure 5 The cross-sectional schematic diagram shown.

[0041] Figure 7 for Figure 6 An enlarged schematic diagram of point A shown.

[0042] Figure 8 for Figure 6 The diagram shows the structure of the end plate.

[0043] Figure 9 The noise and torque are calculated for different ratios of the outer radius of the tooth groove to the maximum outer radius of the rotor core in Embodiment 1 of this utility model.

[0044] Figure 10 The noise and torque are calculated for different ratios of the outer radius of the tooth groove to the maximum outer radius of the rotor core in Embodiment 2 of this utility model.

[0045] Figure 11 The noise and torque are calculated for different ratios of the outer radius of the tooth groove to the maximum outer radius of the rotor core in Embodiment 3 of this utility model.

[0046] Figure 12 The noise and torque are calculated for different ratios of the outer radius of the tooth groove to the maximum outer radius of the rotor core in Embodiment 4 of this utility model.

[0047] Figure 13 Noise and torque when the ratio of the different tooth groove outer radius and the maximum outer radius of the rotor core of the embodiment five of the utility model.

[0048] Figure 14 Noise and torque when the ratio of the different tooth groove outer radius and the maximum outer radius of the rotor core of the embodiment six of the utility model.

[0049] The names of the components marked in the figure are as follows:

[0050] 1, motor housing; 11, gap; 2, stator assembly; 3, rotor assembly; 31, rotor core; 311, pole tooth; 312, tooth groove; 313, weight-reducing hole; 32, magnetic steel; 33, rotor shaft; 34, end plate; 341, step; 4, bearing; 5, fan; 51, extension. DETAILED DESCRIPTION

[0051] The utility model will be further described in detail in combination with the drawings and specific embodiments.

[0052] The brushless motor in the prior art generally includes a rotor and a stator, the rotor includes a rotor core and a magnet embedded in the rotor core. At present, the rotor core is provided with a plurality of magnetic tile installation grooves, even six, sixteen, etc., and the magnetic steel installation grooves are mostly arranged along the circumference of the rotor core. In the case of the same outer diameter of the rotor core, the more the number of magnetic steel installation grooves, the length of the single magnetic steel installation groove along the circumference of the rotor core will be correspondingly reduced, and the smaller the magnetic steel installation groove, the more difficult the processing. Secondly, in order to solve the problem of too many magnetic steel installation grooves, the prior art (CN201810186164.6) discloses that the number of magnetic steel installation grooves is only four, which reduces the processing difficulty of the magnet groove, and controls the ratio of the radius of the tooth groove bottom and the radius of the tooth top (r: R = 0.96-0.98) to reduce the tooth slot effect and reduce noise interference. But this application is applied to ordinary food processors (large motors), and users have a greater tolerance for the noise of ordinary food processors. When the design requirements of the minimum output torque of the food processor cannot be met, the adverse factors of the increase of the motor noise can be weakened. That is to say, in the ordinary food processor (large motor), there is a contradiction between the motor noise and the output torque.

[0053] Furthermore, existing miniaturized food processing machines utilize brushless motors, which are difficult to integrate with the aforementioned patent (CN201810186164.6). This patent addresses how to maximize the drive motor's speed under light or no-load conditions. The range of r:R = 0.96-0.98, set under light or no-load conditions, is also aimed at achieving the highest motor speed. Therefore, there is no inspiration to combine this application with the aforementioned miniaturized food processing machine to reduce motor noise during processing by changing the rotor structure or other structural designs. Miniaturization scenarios have even stricter noise requirements; low noise is one of the performance requirements for miniaturized applications. In conclusion, even if this patent is combined with a miniaturized food processing machine, the technical contradiction of balancing motor noise and output torque under processing conditions remains.

[0054] To address the technical challenge of balancing motor noise and output torque in existing miniaturized brushless motors, this application provides a food processing machine, such as... Figures 1-14 As shown, the food processing machine of this application includes a variable frequency motor, which includes a motor housing 1, a stator assembly 2, a rotor assembly 3, and a fan 5. It should be noted that in this application, "miniaturized rotor" refers to a rotor with only a small outer diameter. When applied to a brushless motor, "miniaturized rotor" results in a "miniaturized brushless motor." The food processing machine refers to a soymilk maker, a blender, a portable juicer, etc. A blender can have an integral frame housing, with a cup and a main unit inside the frame housing, and a miniaturized variable frequency motor installed inside the main unit; a blender can also have a separate cup and main unit, with the main unit connected to the bottom of the cup, and a miniaturized variable frequency motor installed inside the main unit; a soymilk maker can have a top-mounted motor head, with a miniaturized variable frequency motor installed inside the motor head, etc.

[0055] The motor housing 1 has a cavity; the stator assembly 2 is installed in the cavity; the rotor assembly 3 is disposed in the stator assembly 2, including a rotor core 31, a plurality of magnets 32 embedded in the rotor core 31, and a rotor shaft 33 passing through the rotor core 31. The rotor core 31 has a plurality of pole teeth 311 protruding outward along its outer periphery, and a tooth groove 312 is formed between two adjacent pole teeth 311. Each pole tooth 311 and each magnet 32 ​​are arranged in a one-to-one correspondence. The distance between the tooth tip of the pole tooth 311 and the center of the rotor core 31 is R, where 8≤R≤17mm, and the distance between the bottom of the tooth groove 312 and the center of the rotor core 31 is r.

[0056] It should be noted that the overall noise of the motor is the noise under actual operating conditions, which is the sum of bearing noise, wind noise, and electromagnetic noise. Bearing noise is mechanical noise, generally generated when the shaft rotates at high speed. In this embodiment, bearing noise can generally be set as a constant. The closer the rotor core 31 is to a cylinder, the lower the wind noise. When the rotor core 31 is cylindrical, the wind noise is 0; however, it will increase the cogging torque. Therefore, in this embodiment, the rotor core 31 is chamfered, so that the rotor core 31 has a tooth groove 312. The distance between the bottom of the tooth groove 312 and the center of the rotor core 31 is r. An uneven air gap is formed between the rotor core 31 and the outer circular stator assembly 2. The air gap is small at the tooth groove 312 and large at the tooth tip of the pole tooth 311. In this way, the air gap magnetic flux density distribution is close to a sine wave, which helps to reduce the cogging torque, reduce electromagnetic noise, and thus reduce the overall noise of the motor. The outer circumference of the rotor core 31 cannot be too round, as this would increase the overall noise during motor machining. This is because excessive roundness leads to increased cogging torque, which in turn increases electromagnetic noise. The slots 312 of the rotor core 31 also cannot be too deep, as this reduces the effective volume of the rotor core and consequently reduces the output torque.

[0057] Example 1

[0058] like Figure 9 As shown, in this embodiment, the food processing machine includes a variable frequency motor, which includes a stator assembly 2 and a rotor assembly 3. The rotor assembly 3 includes a rotor core 31, four magnets 32, and a rotor shaft 33. The rotor core 31 has four outwardly protruding pole teeth 311 along its outer periphery, and a tooth groove 312 is formed between two adjacent pole teeth 311. The number of tooth grooves 312 is four. The height of the rotor core is H, the maximum radial dimension of the rotor core is D, 2R = D, the maximum outer diameter R of the rotor core 31 is 8mm, H is 16mm, and D:H is 1. The rotor core has a small volume, and when applied in a portable food processing machine, it can still meet the requirements of high output torque and low noise, as detailed below:

[0059] from Figure 9(ordinate left: indicates the motor output torque value, unit mN.m; ordinate right: the overall noise of the motor under the processing condition, unit decibel; abscissa: indicates the ratio of the distance R between the tooth top of the pole tooth 311 and the center of the rotor core 31 and the distance r between the bottom of the tooth groove 312 and the center of the rotor core 31.) It can be seen that the overall motor output torque is greater than 45 mN.m, which meets the minimum output torque (30 mN.m) requirement of the miniaturized portable food processor. With the increasing ratio of r:R, the motor output torque gradually increases. Secondly, the overall noise of the motor under the processing condition gradually decreases and then gradually increases. When r:R is 0.88, the motor noise is the smallest. When r:R approaches 0.88, the overall noise of the motor rises relatively gently, and the output torque of the motor rises relatively fast. When r:R is from 0.8 to 0.81, the overall noise of the motor changes by nearly 3 decibels. Since decibel is a unit for measuring sound intensity and is usually used to represent the gain of sound, a 3-decibel reduction in noise corresponds to a 50% reduction in sound intensity. Therefore, when r:R is from 0.8 to 0.81, the overall noise of the motor changes suddenly, that is, when r:R≤0.8, the user experience performance is poor. Similarly, when r:R is from 0.93 to 0.94, the overall noise of the motor increases by nearly 2 decibels, and the overall noise of the motor changes suddenly, but the improvement of the output torque of the motor is not significant. Therefore, when 0.81≤r / R≤0.93 (dashed line box) in the embodiment, low noise and high output torque can be achieved, so that in the miniaturized portable food processor, the overall noise of the motor is less than 45 decibels, and the output torque is greater than or equal to 30 mN.m.

[0060] Table I: The overall noise and output torque of the motor corresponding to different r:R in Example 1.

[0061]

[0062] In the embodiment, when ice and other smooth and hard food materials are crushed, the ice may collide with the knife assembly, and the hard food material may be stuck on the knife. The demand for instantaneous output torque increases. When high-fiber food materials such as celery are crushed, the food materials are not broken by the crushing knife, and the food materials may be wrapped around the crushing knife assembly, which also increases the demand for instantaneous output torque. Under these special conditions, the portable food processor of the embodiment can still achieve high output torque and low noise.

[0063] Example Two

[0064] As Figure 10As shown, in the embodiment, the food processor comprises a variable frequency motor, the variable frequency motor comprises a stator assembly 2 and a rotor assembly 3, the rotor assembly 3 comprises a rotor core 31, four magnetic steels 32 and a rotor shaft 33, the outer periphery of the rotor core 31 is outwardly convexly provided with four pole teeth 311, a tooth slot 312 is formed between adjacent two pole teeth 311, and the number of tooth slots 312 is four. The height of the rotor core is H, the maximum radial dimension of the rotor core is D, 2R=D, the maximum outer diameter R of the rotor core 31 is 17mm, H is 34mm, and D:H is 1.

[0065] From Figure 10 (Left ordinate: represents the motor output torque value, unit mN.m; right ordinate: overall noise of the motor under processing conditions, unit decibel; abscissa: represents the ratio of the distance R between the tooth top of the pole tooth 311 and the center of the rotor core 31 and the distance r between the slot bottom of the tooth slot 312 and the center of the rotor core 31.) It can be seen that the overall motor output torque is greater than 80mN.m, and the miniaturized brushless motor can be applied to the larger food processor to meet the minimum output torque (80mN.m) requirement. With the increasing ratio of r:R, the motor output torque gradually increases. Secondly, the overall noise of the motor under processing conditions gradually decreases and then gradually increases, the motor noise is the smallest when r:R is 0.90, the overall noise of the motor increases slowly when r:R approaches 0.90, and the motor output torque increases rapidly. When r:R is from 0.81 to 0.82, the overall noise of the motor changes by nearly 3 decibels, so that the overall noise of the motor changes suddenly, and when r:R≤0.81, the user experience performance is poor. Similarly, when r:R is from 0.94 to 0.95, the overall noise of the motor changes suddenly, but the improvement of the motor output torque is not significant. Therefore, when 0.82≤r / R≤0.94 (dotted line box) in the embodiment, low noise and high output torque can be realized. The miniaturized brushless motor in the embodiment is applied to the larger ordinary food processor, the overall noise of the motor is less than 68 decibels, and the output torque is greater than or equal to 80mN.m.

[0066] It should be noted that in the prior art, the large brushless motor (large rotor outer diameter) applied in the ordinary food processor, in the case of motor speed of 10000 rpm, the motor noise should be less than or equal to 70 decibels, that is, it meets the test requirements. It is difficult for a large motor to have a motor noise less than 70 decibels. Generally speaking, the greater the motor speed, the greater the motor noise may also increase. However, in the present application, in the case of motor speed of 15000 rpm, that is, higher than the motor speed in the prior art, the motor noise can still be lower than 68 decibels. Although it is only a few decibels lower than the motor noise in the prior art, since decibel is a unit for measuring sound intensity, it is usually used to represent the gain of sound. A 2-3 decibel reduction in noise is equivalent to a 50% reduction in sound intensity, which significantly improves the user experience performance.

[0067] Table II: Motor overall noise and output torque corresponding to different r:R of Example II.

[0068]

[0069] Example III

[0070] As Figure 11 shown, in this embodiment, the maximum outer diameter R of the rotor core 31 is increased without changing the rotor core 31H. The food processor includes a variable frequency motor, which includes a stator assembly 2 and a rotor assembly 3. The rotor assembly 3 includes a rotor core 31, four magnetic steels 32, and a rotor shaft 33. The rotor core 31 has four pole teeth 311 protruding outward along the outer periphery, and tooth slots 312 are formed between adjacent two pole teeth 311. The number of tooth slots 312 is four. The height of the rotor core is H, the maximum radial dimension of the rotor core is D, 2R=D, the maximum outer diameter R of the rotor core 31 is 8mm, H is 14.5mm, and D:H is 1.1.

[0071] From Figure 11(ordinate left: indicates the motor output torque value, unit mN.m; ordinate right: the overall noise of the motor under the processing condition, unit decibel; abscissa: indicates the ratio of the distance R between the tooth top of the pole tooth 311 and the center of the rotor core 31 and the distance r between the slot bottom of the tooth slot 312 and the center of the rotor core 31.) It can be seen that as the ratio of r:R increases, the motor output torque gradually increases. Secondly, the overall noise of the motor under the processing condition gradually decreases first and then gradually increases, when r:R is 0.88, the motor noise is the smallest, when r:R tends to 0.88, the overall noise of the motor rises slowly, and the output torque of the motor rises fast. When r:R is from 0.81 to 0.82, the overall noise of the motor has a sudden change, that is, when r:R≤0.81, the user experience performance is poor. Similarly, when r:R is from 0.93 to 0.94, the overall noise of the motor increases by nearly 4 decibels, the overall noise of the motor has a sudden change, but the improvement of the output torque of the motor is not significant. Therefore, when 0.82≤r / R≤0.93 (dashed line box) in the embodiment, low noise and high output torque can be realized, the overall noise of the motor is even lower than 45 decibels, and the output torque is greater than or equal to 30 mN.m, which meets the performance requirements of high output torque and low noise of the small and portable food processor.

[0072] Table three: the overall noise and output torque of the motor corresponding to different r:R in example three.

[0073]

[0074] Example four

[0075] As Figure 12 shown, in the embodiment, the food processor includes a variable frequency motor, the variable frequency motor includes a stator assembly 2 and a rotor assembly 3, the rotor assembly 3 includes a rotor core 31, four magnetic steels 32 and a rotor shaft 33, the outer periphery of the rotor core 31 is outwardly convex with four pole teeth 311, a tooth slot 312 is formed between adjacent two pole teeth 311, and the number of tooth slots 312 is four. The height of the rotor core is H, the maximum radial dimension of the rotor core is D, 2R=D, the maximum outer diameter R of the rotor core 31 is 8mm, H is 17.8mm, and D:H is 0.9.

[0076] From Figure 12(ordinate left: indicates the motor output torque value, unit mN.m; ordinate right: the overall noise of the motor under the processing condition, unit decibel; abscissa: indicates the ratio of the distance R between the tooth top of the pole tooth 311 and the center of the rotor core 31 and the distance r between the bottom of the tooth groove 312 and the center of the rotor core 31.) It can be seen that the overall motor output torque is greater than 45 mN.m, which meets the minimum output torque (30 mN.m) requirement of the miniaturized portable food processor, and the motor output torque gradually increases as the ratio of r:R increases. Secondly, the overall noise of the motor under the processing condition gradually decreases and then gradually increases, and when r:R is 0.90, the motor noise is the smallest, and when r:R approaches 0.90, the overall noise of the motor rises slowly, and the motor output torque rises quickly. When r:R is from 0.82 to 0.83, the overall noise of the motor has a large difference, that is, the overall noise of the motor has a sudden change when r:R is from 0.82 to 0.83, that is, when r:R≤0.82, the user experience performance is poor. Similarly, when r:R is from 0.93 to 0.95, the motor noise has a large difference, and the overall noise of the motor also has a sudden change, but the improvement of the motor output torque is not significant. Therefore, when 0.83≤r / R≤0.93 (dashed line box) in the embodiment, low noise and high output torque can be achieved, so that in the miniaturized portable food processor, the overall noise of the motor is even lower than 45 decibels, and the output torque is greater than or equal to 30 mN.m.

[0077] Table Four: The overall noise and output torque of the motor corresponding to different r:R of Example Four.

[0078]

[0079] From the research data of Examples One to Four, it can be seen that the overall volume of the rotor core determines the effective volume of the rotor core, and in turn determines the size of the output torque of the motor. When D:H is close to 1, the volume of the rotor core can be large or small. Specifically, when the volume of the rotor core is large, the output torque is also large (which can be not less than 80 mN.m), and the rotor core with large volume can be applied to non-miniaturized food processors. When the volume of the rotor core is small, the output torque is still large (which can be not less than 30 mN.m), and the miniaturized rotor can still meet the torque demand of portable food processors.

[0080] Comparing Example One with Example Two, it can be seen that when the ratio of the maximum radial dimension (D) of the rotor core to the height (H) of the rotor core is 1, the range of r:R that can be taken is the largest, and r:R can be taken to be 0.83-0.93. Figures 9-10 The D:H of the rotor cores with different volumes is 1. Figure 9 The volume of the rotor core selected in the study is less than Figure 10 The volume of the rotor core selected solves the contradiction between low noise and high output torque,Figure 9 Even with a miniaturized rotor, the torque requirements of portable food processors can still be met. Figure 9 The range of r:R is relatively Figure 10 Moving to the left, the rotor core of the portable food processor needs to have deeper grooves compared to the rotor core of a regular food processor, which can further reduce noise (≤45dB) to meet the stringent user experience performance requirements. Figure 10 By using miniaturized rotors, the high torque requirements of ordinary food processing machines can still be met. Figure 10 The range of r:R is relatively Figure 9 Moving it to the right allows for a shallower tooth groove to meet the requirements of high output torque (≥80mN.m), thereby satisfying the performance requirements of the product itself.

[0081] A comparison of Examples 1 with Examples 3 and 4 shows that the rotor cores are the same and are all miniaturized. In Example 3, the rotor core D:H is 1.1 and r:R is 0.82-0.93; in Example 4, the rotor core D:H is 0.9 and r:R is 0.83-0.93. D:H approaches 1, from... Figures 11-12 In the middle r: the range that R can take compared to Figure 9 Slightly narrowing the range, the r:R ratio reaches its maximum when the ratio of the maximum radial dimension (D) to the height (H) of the rotor core is both 1. In other words, the closer D:H is to 1 (D:H is 0.9-1.1), the wider the range of r:R can be (r:R is 0.83-0.93) while maintaining low noise and high output torque. This allows for a larger range of selectable tooth groove depths, reducing machining difficulty. This is especially beneficial for machining smaller rotor cores, as even with shallower tooth grooves (reduced machining difficulty), the high output torque and low noise performance requirements can still be met.

[0082] Example 5

[0083] like Figure 13 As shown, in this embodiment, the food processing machine includes a variable frequency motor, which includes a stator assembly 2 and a rotor assembly 3. The rotor assembly 3 includes a rotor core 31, four magnets 32, and a rotor shaft 33. The rotor core 31 has four pole teeth 311 protruding outward along its outer periphery, and a tooth groove 312 is formed between two adjacent pole teeth 311. The number of tooth grooves 312 is four. The height of the rotor core is H, the maximum radial dimension of the rotor core is D, 2R = D, the maximum outer diameter R of the rotor core 31 is 10.25 mm, H is 35 mm, and the D:H ratio is 0.6.

[0084] from Figure 13(ordinate left: indicates the motor output torque value, unit mN.m; ordinate right: the overall noise of the motor under the processing condition, unit decibel; abscissa: indicates the ratio of the distance R between the tooth top of the pole tooth 311 and the center of the rotor core 31 and the distance r between the bottom of the tooth groove 312 and the center of the rotor core 31.) It can be seen that as the ratio of r:R increases, the motor output torque gradually increases; secondly, the overall noise of the motor under the processing condition gradually decreases first and then gradually increases, when r:R is 0.90, the motor noise is the smallest, when r:R tends to 0.90, the overall noise of the motor rises relatively gently, and the output torque of the motor rises relatively fast. When r:R is from 0.83 to 0.84, the overall noise of the motor has a large difference, which makes the overall noise of the motor change suddenly, when r:R is less than or equal to 0.83, the user experience performance is poor. Similarly, when r:R is from 0.93 to 0.94, the overall noise of the motor changes suddenly, but the improvement of the output torque of the motor is not significant. Therefore, when 0.84≤r / R≤0.93 (dashed line box) in the embodiment, low noise and high output torque can be realized, and when the small brushless motor is applied to the large food processor, the overall noise of the motor is less than 68 decibels, and the output torque is greater than or equal to 80 mN.m.

[0085] Table five: the overall noise and output torque of the motor corresponding to different r:R of example five.

[0086]

[0087] The D:H of example five is less than 1, and the effective volume of the variable frequency motor is large, which is the research and development principle of the small rotor, which expands the application of the small rotor in the non-small food processor. Only the outer diameter of the rotor is reduced, not the whole rotor. The smaller outer diameter of the rotor helps to reduce the size in the radial direction, making it easier for users to hold in the radial direction, improving the portability of the non-small food processor, and further improving the user experience performance. By increasing the thickness of the rotor core 31, the output torque of the motor is strengthened to meet the use demand of large output torque of ordinary food processors (such as soybean milk machine, broken wall machine, etc.). Generally, the output torque of the variable frequency motor should be not less than 80 mN.m to meet the performance demand of the product itself. In the ordinary traditional food processor, based on setting the small rotor core 31 (8≤R≤17mm), and by setting the length of the rotor form (D:H is less than 1) is longer, and by setting the reasonable depth of the tooth groove 312, the ratio of r:R is set to 0.84-0.93, the overall noise of the motor can be less than 68 decibels. It can also ensure the effective volume of the rotor core 31 to meet the output torque demand of the small motor, so that the output torque of the variable frequency motor is not less than 80 mN.m, which is the performance demand of the product itself required by the ordinary food processor. It also solves the technical contradiction between the motor noise and the output torque in the non-small food processor.

[0088] Example Six

[0089] As Figure 14 shown in the present embodiment, the food processor comprises a variable frequency motor, the variable frequency motor comprises a stator assembly 2 and a rotor assembly 3, the rotor assembly 3 comprises a rotor core 31, four magnetic steels 32 and a rotor shaft 33, the outer periphery of the rotor core 31 is outwardly convex with four pole teeth 311, a tooth slot 312 is formed between adjacent two pole teeth 311, and the number of tooth slots 312 is four. The height of the rotor core is H, the maximum radial dimension of the rotor core is D, 2R = D, the maximum outer diameter R of the rotor core 31 is 10.25 mm, H is 10 mm, and D:H is 2.05.

[0090] From Figure 14 (the ordinate left: represents the motor output torque value, unit mN.m; the ordinate right: the overall noise of the motor under the processing condition, unit decibel; the abscissa: represents the ratio of the distance R between the tooth top of the pole tooth 311 and the center of the rotor core 31 and the distance r between the slot bottom of the tooth slot 312 and the center of the rotor core 31.) It can be seen that as the ratio of r:R increases, the motor output torque gradually increases. Secondly, the overall noise of the motor under the processing condition gradually decreases first and then gradually increases, when r:R is 0.89, the motor noise is the smallest, when r:R tends to 0.89, the overall noise of the motor rises slowly, and the output torque of the motor rises fast. When r:R is from 0.83 to 0.84, the overall noise of the motor has a large difference, and the overall noise of the motor has a sudden change, that is, when r:R≤0.83, the user experience performance is poor. Similarly, when r:R is from 0.92 to 0.93, the overall noise of the motor increases significantly, the overall noise of the motor has a sudden change, but the improvement of the output torque of the motor is not significant. Therefore, in the present embodiment, when 0.84≤r / R≤0.92 (dotted line box), low noise and high output torque can be realized, the overall noise of the motor is even lower than 45 decibels, and the output torque is greater than or equal to 30 mN.m, which meets the performance requirements of high output torque and low noise of small and portable food processors.

[0091] Table Six: The overall noise and output torque of the motor corresponding to different r:R in Example Six.

[0092]

[0093] From the above research data, it can be seen that the D:H of Example Three and Example Six is greater than 1, the shape of the rotor core 31 is more flattened, and the effective volume of the variable frequency motor is smaller, which is generally used in small portable food processors (for example, juicers, etc.). The use requirement of output torque of portable small food processor is lower, and the output torque of the variable frequency motor is generally not less than 30 mN.m. Based on the setting of small rotor core 31 (8≤R≤17 mm), and by setting the rotor shape with shorter length of rotor core 31 (D:H is greater than 1), and by setting a reasonable tooth groove 312 depth, through the intersection of the values of r:R of Example Three and Example Six, when r:R is 0.84-0.92, the overall noise of the motor can be less than 45 decibels, meeting the performance requirements of user experience. It can also ensure the effective volume of the rotor core 31, meet the output torque requirement of the small variable frequency motor, so that the output torque of the variable frequency motor is not less than 30 mN.m, which is the performance requirement of the product itself required to be achieved by the portable small food processor. It also solves the technical contradiction between the motor noise and the output torque of the small food processor.

[0094] From the research results of Example Five and Example Six, it can be seen that the shape of the small rotor can be flattened or elongated. When the maximum outer diameter D of the rotor core 31 can be greater than or equal to the height H of the rotor core 31, the shape of the rotor core 31 is more flattened, which makes the main machine more flattened and compresses the axial size of the whole machine, which is beneficial to improve the portability of the whole machine. Generally, the small brushless motor can be applied to small portable food processors. When the maximum outer diameter D of the rotor core 31 can be less than the height H of the rotor core 31, the shape of the rotor core 31 is more elongated, which reduces the radial size of the variable frequency motor, thereby reducing the radial size of the whole machine. Within the radius range of the small rotor core 31 (8≤R≤17 mm), if the length of the rotor increases, the output torque of the motor will also increase accordingly, and even some food processors with higher output torque requirements and larger machine volume can be used, so that the small variable frequency motor has a wider application value in food processors.

[0095] According to the research data of Example One and Example Two, compared with Example Three to Example Six, when the ratio of the maximum radial size (D) of the rotor core to the height (H) of the rotor core is 1, the range of r:R that can be taken is the largest. For example, the r:R of Example One is 0.81-0.93, which can be applied to small brushless motors to meet the high output torque and low noise. Similarly, by comparing Example Three and Example Four with Example Five and Example Six, it can be seen that the closer D:H is to 1, the larger the range of r:R that can be taken is. When D:H gradually deviates from 1, the range of r:R that can be taken gradually narrows.

[0096] Secondly, the research data of example three, example four, example six, and example five are compared, that is, the range of r:R corresponding to Figure 11 , Figure 12 , Figure 14 The range of r:R is shifted to the left compared to Figure 13 The rotor volume in Figure 11 , Figure 12 , Figure 14 is smaller than the rotor volume in Figure 13 The rotor core of the portable food processor needs to be made deeper than the rotor core of the ordinary food processor, which can further reduce the noise (≤45dB) to meet the stringent user experience performance requirements.

[0097] In addition, when D:H is 0.8, 0.7,..., or D:H is 1.2, 1.3,..., the trend of motor noise and output torque change is similar, which is not described here due to space limitations. When D:H is closer to 1, the range of r:R that can be taken is wider, and the size of the tooth groove depth can be selected in a larger range.

[0098] It should be noted that the height of the rotor core 31 is H, the maximum radial dimension of the rotor core 31 is D, and 2R=D, where R is 8-17mm, H is maximum 44mm, and H is minimum 5mm, that is, when D is 34mm, H is 5mm; when D is 16mm, H is 44mm. If H<5mm, the motor efficiency decreases sharply, the processing yield and utilization rate of the magnet steel 32 are very low, and the manufacturability is poor. If H is greater than 44, the rotor assembly 3 will produce obvious radial shaking, which will easily bring about larger motor noise, and the motor noise is much larger than the maximum noise limit, which does not meet the user performance requirements.

[0099] From the above research data, the rotor core 31 of the present application is a salient pole structure rotor, and by reasonably designing the depth of the rotor core 31 tooth groove 312, the small-sized brushless motor with a small-sized rotor (8≤R≤17mm) has small noise and large output torque under processing conditions. It not only guarantees the performance requirements of the product itself, but also meets the user experience performance requirements on the small-sized food processor. It should be noted that when R<8mm, the rotor structure magnetic pole slot size tends to be limited, the processing yield and utilization rate of the magnet steel 32 are very low, the manufacturability is low, and mass production is not convenient. When R>17mm, the overall diameter of the motor is too large, which will greatly increase the overall noise of the motor, and does not meet the design requirements of the small motor with a small rotor, sacrificing the radial size of the whole machine.

[0100] The specific reason is that when the small rotor 8≤R≤17 mm, r:R is large (greater than 0.92), if the distance between the tooth top of the pole tooth 311 and the center of the rotor core 31 is unchanged, the distance between the slot bottom of the tooth slot 312 and the center of the rotor core 31 is large, that is, the tooth slot 312 is shallow, and the outer periphery of the rotor core 31 tends to be a full circle. Although it can meet the output torque demand of the small brushless motor (wherein the output torque refers to the rated load torque, that is, the rated torque when processing food materials), the air gap between the motor stator and the rotor tends to be uniform, the air gap magnetic flux density distribution under the magnet is closer to a trapezoidal wave, there are more harmonics, thereby causing the cogging torque to become large, and the overall noise of the motor increases sharply. Based on the fact that the small brushless motor has strict noise requirements, it is obvious that it cannot meet the user's experience performance demand. When r:R is small (less than 0.84), if the distance between the tooth top of the pole tooth 311 and the center of the rotor core 31 is unchanged, the distance between the slot bottom of the tooth slot 312 and the center of the rotor core 31 is small, that is, the tooth slot 312 is deep, the rotor core 31 has a more obvious salient pole shape, the effective volume of the rotor core 31 is reduced, which reduces the output torque of the motor, and it is difficult to meet the performance demand of the product itself; and it also increases the overall noise of the motor under the processing working condition, because it is easy to produce large wind noise, and still cannot meet the user's experience performance demand.

[0101] Therefore, for the small rotor 8≤R≤17 mm, only when the ratio of the distance (r) between the slot bottom of the tooth slot 312 and the center of the rotor core 31 and the distance (R) between the tooth top of the pole tooth 311 and the center of the rotor core 31 is moderate (r:R is 0.84-0.92), the cogging torque of the small variable frequency motor can be controlled to be not too large by setting a reasonable depth of the tooth slot 312, the strict overall noise requirement is met, and the user's experience performance demand is met; in addition, the effective volume of the rotor core 31 can be ensured, the output torque demand of the small variable frequency motor is met, the performance demand of the product itself is met, and the technical contradiction that the motor noise and the output torque are difficult to balance is solved. At the same time, the overall noise sources of the food processor include the crushing of the crushing assembly, the resonance noise of the main machine and the motor, and the motor noise has a greater impact on the overall noise of the food processor. In the present application, the motor noise is reduced, which can assist in reducing the noise of the entire crushing system, thereby greatly reducing the overall noise of the food processor, so as to ensure the user's experience performance demand on the food processor.

[0102] Since noise is one of the performance requirements of small motor miniaturization scenarios, the existing technology (CN201810186164.6) discloses an ordinary food processor (large motor), and the use scenario is in the light load or no load state. How to make the speed of the driving motor reach the highest. Based on the use scenario of the large motor in the light load or no load state, the range of r:R=0.96-0.98 is set, which reduces the noise and ensures the efficiency of the driving motor. The efficiency of the driving motor is still to further realize the motor performance of the highest speed. However, the overall noise of the small motor in the miniaturization scenario requires more stringent, obviously, in the case of understanding that users have a high tolerance for the noise of ordinary food processors, in order to ensure the output torque of the large motor, the impact of the noise will be sacrificed. There is a contradiction between the motor output torque and the noise in the large motor. Therefore, on the basis of the existing technology, there is no enlightenment to make the diameter of the variable frequency motor smaller while making the tooth groove deeper, which makes it difficult to solve the technical contradiction between the motor noise and the output torque in the miniaturization brushless motor. Therefore, the present application sets the depth of the rotor core 31 tooth groove 312 through reasonable setting, and the ratio of the distance (r) between the groove bottom of the tooth groove 312 and the center of the rotor core 31 and the distance (R) between the tooth top of the pole tooth 311 and the center of the rotor core 31 is set to 0.84-0.92. The noise is small and the motor output torque is large under the processing condition. Both the performance requirements of the product itself and the experience performance requirements of the user on the miniaturization food processor are met, and the creative labor is paid.

[0103] As shown in Figure 2 The rotor core 31 is circumferentially spaced apart and has a plurality of magnetic steel 32 grooves, each magnetic steel 32 is correspondingly inserted into each magnetic steel 32 groove, and the magnetic steel 32 groove is one-to-one corresponding to the pole tooth 311. It should be noted that the magnetic steel 32 groove and the magnetic steel 32 can be two, four, six, eight or more. As a preferred embodiment, the pole tooth 311 is provided with four, the magnetic steel 32 is provided with four, the magnetic steel 32 groove is provided with four, the four magnetic steels 32 are respectively inserted into the four magnetic steel 32 grooves, and the line connecting the tooth top of each pole tooth 311 and the center of the rotor core 31 is perpendicular to the line connecting the tooth top of the adjacent pole tooth 311 and the center of the rotor core 31. That is, every 90° in the circumferential direction of the rotor core 31 has a pole tooth 311. It should be noted that the center of the rotor core 31 refers to the axis of the rotor shaft 33.

[0104] It can be understood that only four magnetic steel 32 slots are arranged on the rotor core 31, and the magnetic steel 32 is arranged in the magnetic steel 32 slot. Since the magnetic steel 32 slot is machined on the miniaturized rotor, the circumferential length of the miniaturized rotor is small, and by arranging a small number of magnetic steels 32, the machining difficulty of the miniaturized rotor will be greatly reduced, and at the same time, the number of magnetic steels 32 is not too small to ensure the effective volume of the rotor core 31, thereby ensuring that the output torque can meet the needs of the small motor.

[0105] Further, the rotor core 31 is approximately square in radial cross-section, that is, when r:R is 0.84-0.92, the miniaturized rotor core 31 tooth slot 312 is deeply recessed towards the rotor shaft 33 axis, and the rotor core 31 salient pole shape is more obvious. By setting a reasonable tooth slot 312 depth, an approximately square cross-section rotor core 31 can be obtained, so that the small motor tooth slot torque is not too large, meeting the stringent overall noise requirements, thereby meeting the user's experience performance requirements; in addition, the effective volume of the rotor core 31 can be ensured, meeting the output torque requirements of the small motor, thereby meeting the performance requirements of the product itself, solving the technical contradiction that the motor noise and output torque are difficult to balance.

[0106] The upper and lower ends of the rotor core 31 can be provided with counterweights, especially for rotors with a long axial length, which are prone to radial wobble and require counterweights for dynamic balancing. The counterweight is arranged at the end of the rotor core 31, which can prevent the magnetic steel 32 from falling out of the magnetic steel 32 slot. The end plate 34 can also not be provided, and for those relatively flat rotors, the magnetic steel 32 can be glued and installed in the magnetic steel 32 slot to prevent the magnetic steel 32 from falling out of the magnetic steel 32 slot during rotation; see the following embodiments for details.

[0107] In one embodiment, as shown in Figures 1-4 The rotor core 31 upper and lower ends are not provided with counterweight structure, and the fan 5 can also not be provided. Specifically, the motor housing 1 has a mounting cavity accommodating the bearing 4, the rotor shaft 33 penetrates the bearing 4, and the bearing 4 away from the motor housing 1 side and the end of the rotor core 31 have a gap 11.

[0108] It can be understood that, due to the gap 11 between the bearing 4 and the rotor core 31, resonance caused by contact between the two during operation of the motor is prevented, thereby causing the motor to produce additional mechanical noise. On the other hand, by providing a gap 11 between the bearing 4 and the rotor core 31, that is, by not providing any components at the upper and lower ends of the rotor core 31 to achieve counterweight, the rotor core 31 can still be prevented from excessive radial deflection, that is, the motor can have better dynamic balance effect. In this way, without the need to set the counterweight block, the internal structure of the small-sized variable frequency motor is greatly simplified, so that the size of the main machine is greatly reduced, thereby facilitating the miniaturization of the whole machine, and also facilitating the reduction of cost. This setting, as shown in Figure 2 、 Figure 4 , is generally used in variable frequency motors with short rotor cores 31, especially flat rotor cores 31.

[0109] In another embodiment, as shown in Figures 5-8 , the upper and lower ends of the rotor core 31 are provided with a counterweight structure, and a fan 5 is provided. Specifically, the rotor assembly 3 further comprises an end plate 34 sleeved and fixed to the outside of the rotor shaft 33, the end plate 34 is crimped to the end of the rotor core 31 and the end of the magnetic steel 32, and the rotor shaft 33 passes through the end plate 34. It should be noted that the end plate 34 can be a circular ring, or any other shape, as long as it can be crimped to the end of the rotor core 31 and the magnetic steel 32.

[0110] It can be understood that the end plate 34 crimps the rotor core 31 and the magnetic steel 32, which can limit the magnetic steel 32 from being separated from the magnetic steel 32 slot in the axial direction during rotation of the rotor, to ensure normal operation of the rotor core 31. At the same time, the end plate 34 sleeved on the rotor shaft 33 increases the weight of the rotor assembly 3 during rotation of the rotor, preventing the long rotor core 31 from producing obvious radial shaking, thereby achieving dynamic balance of the rotor assembly 3, and further improving the dynamic balance effect of the motor.

[0111] As a preferred embodiment, the outer diameter of the end plate 34 is smaller than the maximum outer diameter of the rotor core 31. It can be understood that, while satisfying the crimping of the upper and lower ends of the magnetic steel 32 by the end plate 34, the outer diameter of the end plate 34 is set to be smaller than the maximum outer diameter of the rotor core 31, so as to reduce the contact area between the end plate 34 and the rotor core 31 as much as possible, reduce the resonance between the two, and further reduce the noise of the motor under processing conditions.

[0112] More specifically, the end plate 34 has a step 341 extending outwardly towards one end of the rotor core 31, and at least part of the step 341 covers the magnetic steel 32. It can be understood that the step 341 can cover the entire magnetic steel 32 or only a part of the magnetic steel 32 in order to be able to press the magnetic steel 32. When only a part of the step 341 covers the magnetic steel 32, the remaining part of the end plate 34 can not be in contact with the rotor core 31 or the magnetic steel 32, and the area of the end plate 34 close to the axis of the rotor shaft 33 and the end of the rotor core 31 has a gap, and the outer edge of the end plate 34 has a step 341 extending towards the magnetic steel 32, and the step 341 can also press the upper and lower ends of the rotor core 31. Only the step 341 is in contact with the rotor core 31 and the magnetic steel 32, which can reduce the contact area of the end plate 34 and the rotor core 31, further reduce the resonance between them, and further facilitate the reduction of the noise of the motor under the working condition.

[0113] In addition, as shown in Figures 5-6 the small-sized variable frequency motor further comprises a fan 5 sleeved and fixed to the outside of the rotor shaft 33, and the fan 5 has an extension 51 along the rotor shaft 33, and the extension 51 abuts against one end of the end plate 34 away from the rotor core 31. It can be understood that the extension 51 is in the form of a sleeve, which is sleeved outside the rotor shaft 33. The fan 5 and the end plate 34 have a certain distance in the axial direction, and the extension 51 abuts against the end plate 34 to realize the positioning and installation between the fan 5 and the end plate 34.

[0114] The height of the end plate 34 is H1, the height of the rotor core 31 is H, and H1:H is 0.075-0.4. Preferably, H1 is 5.5 mm, and H is 35 mm.

[0115] It can be understood that the height of the end plate 34 in the entire rotor assembly 3 cannot be too large or too small, and the sum of the height of the end plate 34 and the height of the rotor core 31 is the overall height of the rotor assembly 3. When H1:H is 0.075-0.4, through the end plate 34 pressed on the end of the rotor core 31, the self-weight of the rotor assembly 3 is increased during the rotation of the rotor, so as to prevent the long rotor core 31 from producing obvious radial swing, so as to realize the dynamic balance of the rotor assembly 3; at the same time, since the rotor core 31 is small-sized, the outer diameter is limited, and the volume needs to be increased through the height, therefore, the height of the rotor core 31 is ensured to ensure the effective volume of the interaction between the rotor core 31 and the stator assembly 2, and further effectively ensure the output torque of the motor.

[0116] When H1:H is less than 0.075, the length of the rotor core 31 is too long, which can cause the rotor core 31 to produce obvious radial swing, the dynamic balance effect of the end plate 34 is not significant, and larger motor noise is easily caused. When H1:H is greater than 0.4, the length of the rotor core 31 is too short, it is difficult to ensure the effective volume of the interaction between the rotor core 31 and the stator assembly 2, and then the output torque of the motor is affected.

[0117] In one embodiment, as shown in Figure 2 A plurality of lightening holes 313 are formed in the rotor core 31, and the lightening holes 313 are arranged at intervals with the magnetic steel 32. It can be understood that the lightening holes 313 are arranged in the rotor core 31 to achieve the effect of reducing weight, reduce the load of the motor, ensure the dynamic balance of the motor, reduce the working noise of the motor, and improve the user experience.

[0118] Specifically, the radius of the rotor shaft 33 is R1, the distance between the tooth top of the pole tooth 311 and the center of the rotor core 31 is R, and R1:R is 0.19-0.5. Preferably, R1 is 6.35mm, and R is 20.5mm.

[0119] It can be understood that, since the rotor core 31 is miniaturized, the outer diameter of the rotor core 31 is limited, and the radius of the rotor shaft 33 arranged in the rotor core 31 cannot be too large or too small. When R1:R is 0.19-0.5, the effective volume of the rotor core 31 can be ensured to ensure the effective volume of the interaction between the rotor core 31 and the stator assembly 2, and then the output torque of the motor is ensured; at the same time, during the rotation of the rotor assembly 3, the rotor shaft 33 has enough shear resistance to prevent the rotor shaft 33 from being bent and deformed, and effectively ensure the normal use of the motor.

[0120] When R1:R is less than 0.19, the radius of the rotor shaft 33 is too small, which affects the shear resistance of the rotor shaft 33 during work, and the rotor shaft 33 is easily bent and deformed, and then the normal use of the motor is affected. When R1:R is greater than 0.5, the radius of the rotor shaft 33 is too large, which reduces the radial cross-sectional area of the rotor core 31, reduces the effective volume of the rotor core 31, and may reduce the output torque of the motor.

[0121] In addition to the above preferred embodiments, the technical solutions of the utility model are not limited to the above embodiments, it should be pointed out that the combination of multiple technical solutions in any one embodiment and the combination of the technical solution of any one embodiment and the technical solution of other one or more embodiments are within the protection scope of the utility model. Although the utility model has been described in detail by general description and specific embodiments above, some modifications or improvements can be made on the basis of the utility model, which is obvious to those skilled in the art. Therefore, these modifications or improvements made on the basis of not deviating from the spirit of the utility model all belong to the range of the utility model required to be protected.

Claims

1. A food processor, characterized in that, The variable frequency motor comprises: A motor housing having a cavity; A stator assembly installed in the cavity; A rotor assembly disposed in the stator assembly, comprising a rotor core, a plurality of magnetic steels embedded in the rotor core, and a rotor shaft penetrating through the rotor core, one end of the rotor shaft penetrating out of the motor housing, the outer periphery of the rotor core being outwardly convexly provided with a plurality of pole teeth, a tooth slot being formed between adjacent two pole teeth, each pole tooth and each magnetic steel being one-to-one correspondingly arranged; Wherein, the distance between the pole tooth top and the center of the rotor core is R, 8≤R≤17mm, the distance between the bottom of the tooth slot and the center of the rotor core is r, r:R is 0.84-0.

92.

2. The food processor of claim 1, wherein, The height of the rotor core is H, the maximum radial dimension of the rotor core is D, 2R=D, D: H is 0.9-1.1, r:R is 0.83-0.

93.

3. The food processor of claim 1, wherein, The pole teeth are provided with four, the magnetic steels are provided with four, the line connecting the pole tooth top of each pole tooth and the center of the rotor core is vertically arranged with the line connecting the pole tooth top of the adjacent pole tooth and the center of the rotor core.

4. The food processor of claim 3, wherein, The cross section of the rotor core along the radial direction is approximately square.

5. The food processor of claim 2, wherein, When D: H is less than 1, the output torque of the variable frequency motor is not less than 80mN.m, r:R is 0.84-0.

93.

6. The food processor of claim 2, wherein, When D: H is greater than 1, the output torque of the variable frequency motor is not less than 30mN.m, r:R is 0.84-0.

92.

7. The food processor of claim 1, wherein, The motor housing is provided with a mounting cavity accommodating a bearing, the rotor shaft penetrates through the bearing, and there is a gap between the side of the bearing away from the motor housing and the end of the rotor core.

8. The food processor of claim 1, wherein, The rotor assembly further comprises an end plate fixedly sleeved on the outer rotor shaft, the end plate being press-connected with the end of the rotor core and the end of the magnetic steel, and the rotor shaft penetrating through the end plate.

9. The food processor of claim 8, wherein, The outer diameter of the end plate is smaller than the maximum outer diameter of the rotor core.

10. The food processor of claim 8, wherein, The end plate has a step extending outwardly towards one end of the rotor core, and at least part of the step covers the magnetic steel.

11. The food processor of claim 8, wherein, The food processor further comprises a fan fixedly sleeved on the outer rotor shaft, the fan having an extension along the rotor shaft, the extension abutting against one end of the end plate away from the rotor core.

12. The food processor of claim 8, wherein, The height of the end plate is H1, the height of the rotor core is H, H1: H is 0.075-0.

4.

13. The food processor of claim 1, wherein, A plurality of lightening holes are formed in the rotor core, and the lightening holes are arranged at intervals with the magnetic steels.

14. The food processor of claim 1, wherein, The radius of the rotor shaft is R1, R1:R is 0.19-0.5.

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