A brushless motor with good noise reduction effect for food processing machine

Abstract

The present application provides a brushless motor with good noise reduction effect, which relates to the field of food processing technology. The brushless motor of the present application includes a housing and a rotor assembly and a stator assembly disposed within the housing. The housing includes an upper housing and a lower housing. The upper housing and the lower housing together form a heat dissipation cavity surrounding the stator assembly. A centrifugal fan is disposed within the heat dissipation cavity. The rotor assembly reversely drives the centrifugal fan to rotate in the opposite direction. The side wall of the upper housing is provided with an air inlet, and the side wall of the lower housing is provided with an air outlet for concentrated air discharge. The present application addresses the drawbacks of unstable airflow and high wind noise of centrifugal fans during reverse rotation in a variable frequency motor flat housing side guide mode, achieving stable and reliable air discharge in the reverse high-speed drive mode, thereby improving the overall air inlet and outlet air guide efficiency.

Description

Technical Field

[0001] The present application relates to the field of motor technology, and in particular to a brushless motor with variable frequency drive, forward and reverse rotation functions, and good noise reduction effect. Background Art

[0002] With the development of food processing machines, people have gradually begun to pursue a higher quality user experience. Traditional food processing machines are often driven by series motors due to product pricing restrictions and simple drive requirements. However, series motors have been criticized in the market due to many problems such as large fluctuations in motor transmission efficiency, low axial heat dissipation efficiency, large base size, and obvious noise. There are many structural optimizations in the existing technical field, such as sound insulation covers, shock-absorbing pads, noise reduction cotton, heat dissipation ducts and other different types of technological innovations. However, due to the limitations of the motor's own properties, none of them have achieved significant noise reduction, heat dissipation or miniaturization effects, and there are even fewer products that can solve the above problems at the same time.

[0003] In order to solve problems similar to those mentioned above, the patent text with application number CN202110173563.0 breaks the conventional technical concept and discloses a food processing machine that uses a brushless motor to achieve an overall flat setting of the motor. By circumferentially arranging multiple air inlets and outlets on the upper and lower end covers of the motor, a motor cavity structure with lateral air inlet and outlet is formed, and the noise reduction purpose is achieved by reducing the motor height and the axial flow height.

[0004] However, further innovation and breakthroughs are possible in this area of ​​technology. The applicant's continued research has revealed the following: First, the cooling fan within the motor can be a centrifugal fan. Centrifugal fans accelerate airflow sideways through centrifugal force, improving the efficiency of lateral airflow. Second, in addition to offering a more stable drive, the most valuable advantage of brushless motors is the ability to switch between forward and reverse rotations at will through current control. However, this forward and reverse rotation process is rarely used in existing food processing machines and has not yet fully demonstrated its true value.

[0005] To further innovate this technology, resolving the issues of heat dissipation and wind noise during reverse drive is crucial. For example, due to the variability in wind flow during reverse operation, the actual wind direction and heat dissipation efficiency are significantly reduced. Furthermore, the issue of wind noise exacerbated by airflow collisions during reverse drive remains a challenge.

[0006] In addition, in the patent document CN202110173563.0, multiple heat dissipation holes are also set in the circumferential direction of the end face of the lower bracket. Although the heat in the heat dissipation cavity can be quickly discharged outward, the interference of the heat dissipation holes on the motor noise is ignored. During the rotation of the centrifugal fan, on the one hand, the blades form an acute angle with the retaining ribs when reversing, and the airflow hits the retaining ribs at an acute angle. The impact component is large, resulting in sharper noise inside the motor, and multiple turbulent vortex points are formed at each heat dissipation hole. The wind noise generated by the collision of airflows in the heat dissipation cavity is more obvious; on the other hand, when the airflow overflows from the heat dissipation hole, it will form multiple wind wave sources that spread outward. The wind wave sources of adjacent heat dissipation holes will form wind waves that intersect on the left and right when spreading outward, and form a superposition effect through the interference of waves, thereby enhancing the generation of vibration noise outside the shell.

[0007] Furthermore, when the centrifugal fan blades of a flat motor are driven in high-speed reverse mode, the blades' effect on the airflow and acceleration is particularly pronounced, resulting in increased wind noise and low airflow efficiency. Consequently, the reverse drive performance of brushless motors is often unsatisfactory, leading industry technicians to be reluctant to expand their application of high-speed reverse drive.

[0008] Based on this, how to set up a food processing machine with a flat base, forward and reverse drive functions, and good noise reduction effect of the motor body has gradually become a technical problem that technical personnel in this field urgently need to solve. Summary of the Invention

[0009] The purpose of the present invention is to provide a brushless DC motor with good noise reduction effect. It is aimed at the lateral air guide mode of the flat shell of the variable frequency motor to solve the disadvantages of unstable airflow and high wind noise when the centrifugal fan is reversed, and to achieve stable and reliable air outlet in the reverse high-speed drive mode, thereby improving the overall air inlet and outlet air guide efficiency.

[0010] The above technical problems of this application are mainly solved by the following technical solutions:

[0011] A brushless motor with good noise reduction effect includes a shell and a rotor assembly and a stator assembly arranged in the shell, the shell includes an upper shell and a lower shell, the upper shell and the lower shell together form a noise reduction chamber surrounding the stator assembly, a centrifugal fan is provided in the noise reduction chamber, the rotor assembly drives the centrifugal fan to rotate in the opposite direction by reverse driving, the side wall of the upper shell is provided with an air inlet, and the side wall of the lower shell is provided with an air outlet for concentrated air outlet, the air outlet is arranged radially opposite to the centrifugal fan, and axially overlaps with the guide blade part of the centrifugal fan.

[0012] Furthermore, the angle formed by the two sides of the air outlet and the motor axis is 30° to 120°.

[0013] Furthermore, there is one air outlet, and the angle formed by the two sides of the air outlet and the motor axis is 40° to 100°.

[0014] Furthermore, the air outlet is provided on the inner side wall of the lower shell in an outwardly protruding manner.

[0015] Furthermore, the inner wall of the lower shell is provided with a first guide wall at the reverse side of the air outlet, the first guide wall having an increased distance from the motor axis, and the end of the first guide wall protrudes outward and extends to the air outlet.

[0016] Furthermore, the first guide wall is a guide arc surface or a guide oblique surface for centrally rectifying the reversed airflow of the centrifugal fan.

[0017] Furthermore, the inner side wall of the lower shell also includes a second guide wall arranged on the positive rotation side of the air outlet, and the guide curvature radius of the first guide wall and the second guide wall gradually increases on the side close to the air outlet.

[0018] Furthermore, the centrifugal fan includes a plurality of guide blades symmetrically arranged around the axis center, and the inner side wall of the lower shell also includes a guide air duct at least partially surrounding the centrifugal fan, and the width of the guide air duct is not less than the guide width between adjacent guide blades.

[0019] Furthermore, the central angle of the adjacent guide blade ends around the axis is a, and the central angle of the air outlet around the axis is b, wherein b is 2 to 15 times of a.

[0020] Furthermore, the outer diameter of the guide blade is d1, and the inner diameter of the inner wall of the lower shell is d2, wherein 0.6≤d1 / d2≤0.9.

[0021] The beneficial effects of this application compared with the prior art are:

[0022] 1. The present application provides a brushless DC motor with good noise reduction effect. Compared with the overall structural framework of the existing flat brushless DC motor, the motor further drives the centrifugal fan to reversely drive the airflow in the circumferential direction by reversing the rotor assembly, and then concentrates the air through the air outlet to guide the rectified airflow in the noise reduction chamber outward. Using a centrifugal fan for guidance, on the one hand, because the centrifugal fan guides the air through the outward diverging centrifugal force, it can guide the air radially outward through the air outlet regardless of whether it is rotating forward or reverse. On the other hand, the concentrated air outlet can also solve the problem that the guide blades in the reverse driving mode generate a forward component in the guide tangential direction, which drives the airflow to accelerate rapidly and converge inward, resulting in untimely outlet guidance and low air guide efficiency. Compared with the situation where the air outlets are dispersed in multiple directions, the concentrated air outlet can form a better guiding and rectifying effect, avoid turbulence and wind noise caused by too many air guide directions, and improve the overall air outlet efficiency and heat conduction efficiency of the noise reduction chamber; effectively reduce the turbulence formed when the high-speed airflow is diverted through the air outlet, and reduce the wind noise problem caused by impacting the air duct or air outlet.

[0023] 2. The diameter and area of ​​the air outlet also have a further restrictive significance on the centralized air outlet effect. The preferred angle formed by the two sides of the air outlet and the motor axis is 30°-120°. When the air outlet angle is less than 30°, the airflow inside the noise reduction cavity is limited by the air outlet cross-sectional area, and the actual air outlet efficiency of the air outlet is limited, resulting in congestion of the air outlet and a significant decrease in the overall air guide efficiency, which will prevent the heat inside the motor housing from being dissipated outward in time. When the air outlet angle is greater than 120°, the air guide channel opening is too large, and the centralized rectification air outlet effect begins to gradually decline. Since the air outlet channel is too wide, the diversion directions are too numerous and relatively dispersed, and the wind noise generated by the collision of airflows from different directions is also relatively increased.

[0024] 3. There is one air outlet. By setting a concentrated diameter of the air outlet, the wind noise can be further limited. Preferably, the angle formed between the two sides of the air outlet and the motor axis is between 40° and 100°. By setting a continuous air outlet for concentrated air outlet, the airflow in the noise reduction chamber can be better integrated, and the turbulence caused by the collision of the side wall of the shell when the centrifugal fan passes through multiple circumferential uniform air outlets during reversal can be discharged. Limiting the angle of this air outlet to between 40° and 100° can ensure the wind guide rate of the concentrated air outlet and minimize the collision noise at the air outlet. When the angle is less than 40°, although the wind noise generated at the air outlet is relatively small, the actual wind guide rate is also relatively low; when the angle is greater than 100°, not only will the wind noise generated at the air outlet be relatively large, but the wind guide rate will also drop significantly.

[0025] 4. The air outlet is designed to protrude outward from the inner wall of the lower housing, further limiting the centrifugal fan's outward wind guidance efficiency, allowing airflow to be quickly directed through the outlet. Because the air outlet protrudes outward from the housing guide, the centrifugal force of the centrifugal fan causes the airflow to deviate outward as it passes through the outlet, allowing it to be quickly directed outward. This prevents airflow from circulating and converging within the noise reduction chamber duct, where it could collide with the incoming airflow, disrupting normal air intake efficiency and exacerbating wind noise at the inlet.

[0026] 5. A first guide wall is also provided on the reverse side of the air outlet, transitionally connected to the air outlet. This can further limit the outward air guide efficiency when the centrifugal fan is reversely driven, and at the same time improve the noise level when the motor is reversely driven. When the centrifugal fan is reversely driven by the motor shaft, the airflow is rectified along the side walls of the noise reduction chamber after being thrown out along the centrifugal fan. The rectified airflow moves along the curved surface of the cavity side wall, achieving the first stage of noise reduction through air intake rectification. Then, when passing through the air outlet, it will continue to be guided outward along the first guide wall, and under the action of centrifugal force, it will be smoothly discharged from the air outlet along the guide surface.

[0027] 6. The centrifugal fan is equipped with centrally symmetrical guide blades. By limiting the width of the guide channel surrounding the centrifugal fan to no less than the width between adjacent guide blades, the conversion relationship between the air velocity guided by the guide blades and the rectification efficiency of the lower housing sidewall is optimized, ensuring sufficient space outside the guide blades for rectification. Specifically, the outer diameter of the guide blades is limited to d1 and the inner diameter of the lower housing inner wall is limited to d2, satisfying 0.6≤d1 / d2≤0.9. This allows the interior of the noise reduction chamber to maintain a high flow rate, accelerates the rectification and air guidance rate during the reverse drive process, and avoids turbulence in the airflow direction within the chamber, which can cause collisions and increase noise.

[0028] 7. Furthermore, the guide blades can directly throw out a portion of the airflow when passing through the air outlet, and the remaining part can be rectified and then guided out again. By limiting the ratio of the central angle of the air outlet to the central angle of the end of the guide blade, when the central angle of the air outlet around the axis is 2 to 15 times the central angle of the end of the guide blade, the proportion of the thrown-out part of the airflow and the part that needs to be rectified can be distributed, ensuring that the airflow in the guide duct is reasonable, without excessive accumulation, and ensuring the gas flow rate under low wind noise conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.

[0030] Figure 1 This is a schematic diagram of the structure of a brushless motor with good noise reduction effect shown in an embodiment of the present application;

[0031] Figure 2 This is a schematic diagram of the internal cross-section of a brushless motor shown in an embodiment of the present application;

[0032] Figure 3 This is a schematic structural diagram of a brushless motor rotor assembly according to an embodiment of the present application;

[0033] Figure 4 This is a schematic diagram of the upper housing structure of a brushless motor shown in an embodiment of the present application;

[0034] Figure 5 This is a schematic diagram of the lower housing structure of a brushless motor shown in an embodiment of the present application;

[0035] Figure 6 A schematic diagram of the flow guide structure of the noise reduction cavity is shown in the embodiment of the present application;

[0036] Figure 7 A schematic diagram of the guide structure of the air outlet is shown for an embodiment of the present application;

[0037] Figure 8 A schematic diagram of the guide structure of the guide air duct is shown for an embodiment of the present application;

[0038] Figure 9 This is a schematic diagram showing the relationship between the air outlet angle and the air outlet noise according to an embodiment of the present application;

[0039] Figure 10 This is a schematic diagram showing the relationship between the air outlet angle and the air outlet speed according to an embodiment of the present application;

[0040] Figure 11 Schematic diagram of the changing relationship between the diameter of a centrifugal fan and the air outlet speed shown in an embodiment of the present application.

[0041] Icon: 1-housing, 2-upper housing, 3-lower housing, 4-centrifugal fan, 5-rotor assembly, 6-stator assembly, 7-noise reduction chamber;

[0042] 21-air inlet, 31-air outlet, 32-first guide wall, 33-second guide wall, 34-diverter rib, 41-guide blade, 42-guide air duct;

[0043] 51-motor shaft, 52-rotor core, 53-rotor end plate, 54-rotor bearing;

[0044] 61- stator bracket, 62- stator core, 63- stator coil. DETAILED DESCRIPTION

[0045] The terms "first", "second", "third", etc. are only used to distinguish and describe, and do not indicate the order of arrangement, nor can they be understood as indicating or implying relative importance.

[0046] Furthermore, terms such as "horizontal," "vertical," and "overhanging" do not necessarily imply that a component must be absolutely horizontal or overhanging, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but rather that it can be slightly tilted.

[0047] In the description of this application, it should be noted that the terms "inside", "outside", "left", "right", "up", "down", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings, or are the directions or positional relationships in which the product of the application is usually placed when in use. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they should not be understood as limitations on this application.

[0048] In the description of this application, unless otherwise clearly specified and limited, the terms "set", "install", "connected" and "connect" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be a connection between the internal parts of two elements.

[0049] The technical solution of this application will be clearly and completely described below with reference to the accompanying drawings.

[0050] Please refer to Figure 1 and Figure 2 The present invention provides a schematic diagram of a brushless motor structure with excellent noise reduction performance, as shown in an embodiment of the present invention. The brushless motor comprises a housing 1, a rotor assembly 5, and a stator assembly 6 disposed within the housing 1. The housing 1 comprises an upper housing 2 and a lower housing 3. The upper housing 2 and the lower housing 3 together form a noise reduction cavity 7 that at least partially surrounds the stator assembly 6.

[0051] Among them, a centrifugal fan 4 driven by the rotation of the rotor assembly is provided in the noise reduction chamber 7, and an air inlet 21 is provided on the lateral circumference of the upper shell 2, and an air outlet 31 concentrated on one side is provided on the lower shell 3. The centrifugal fan 4 rotates to throw the air flow in the noise reduction chamber 7 outward, forming a circulating airflow that continuously flows from the air inlet 21 to the air outlet 31.

[0052] During an operation, when the rotor assembly 5 rotates in the opposite direction, the centrifugal fan 4 will be driven to rotate in the opposite direction accordingly. Since the guide blades push the airflow in the reversal process, in addition to forming an outward centrifugal component, it will also form a tangential component in the same direction of movement of the guide blades, causing the airflow to accelerate rapidly during the reversal process, and when the speed gradually increases, it will also form a certain tendency to converge toward the center of the guide blades. However, when passing through the side wall of the lower shell, it can be guided along the inner wall for rectification and guided to the air outlet 31, concentrated at the air outlet 31 and quickly discharged outward. This can not only increase the rectification coverage range in the circumferential direction of the centrifugal fan 4, avoid the formation of turbulence inside the noise reduction chamber to hinder the circulation of the air duct, but also concentrate the air outlet to increase the guide speed of the noise reduction chamber, and since the airflow at the outlet has better consistency after rectification, the wind noise problem generated at the air outlet is also greatly reduced.

[0053] It can be understood that the noise reduction cavity 7 formed by the upper shell 2 and the lower shell 3 can be other spaces inside the shell 1 except the stator assembly 6 and the rotor assembly 5, including the gap between the stator assembly 6 itself and / or the gap between the stator assembly 6 and the rotor assembly, and the airflow inside the noise reduction cavity 7 can pass through it to take away heat.

[0054] Please refer to Figure 3 , which is a schematic diagram of the structure of the rotor assembly 5 shown in an embodiment of the present application. The rotor assembly 5 includes a motor shaft 51 set at the center of the brushless motor, a rotor core 52 sleeved and fixed on the motor shaft 51, and rotor end plates 53 and rotor bearings 54 assembled at both ends of the rotor core 52. The stator assembly 6 is circumferentially arranged around the outside of the rotor assembly 5, including a stator bracket 61, a stator core 62 and a stator coil 63 set on the stator bracket 61. By controlling the stator assembly 6 to pull the rotor assembly 5, the motor shaft 51 and the centrifugal fan 4 are driven to achieve forward and reverse rotation.

[0055] In one embodiment, the rotor end plate 53 includes an upper end plate and a lower end plate, respectively secured to the upper and lower ends of the rotor core 52. The rotor bearing 54 includes an upper bearing and a lower bearing secured to either side of the rotor end plate 53. The centrifugal fan 4 is secured and fixed between the lower end plate and the lower bearing, and is driven to rotate in a forward or reverse direction synchronously with the rotor assembly 5. It will be appreciated that the rotor core 52, the rotor end plate 53, and the centrifugal fan 4 may be secured to each other via axial riveting or structural retaining engagement, and rotate synchronously about the motor shaft 51.

[0056] In another embodiment, the stator assembly 6 is disposed circumferentially around the rotor assembly 5, wherein a plurality of stator coils 63 are provided, evenly distributed around the rotor assembly 5 and fixed to the stator bracket 61. Preferably, the centrifugal fan 4 is disposed below the rotor assembly 5 and the stator assembly 6, with nine stator coils 63 evenly distributed around the circumference of the rotor assembly 5. Gaps are provided between adjacent stator coils 63 and between the stator coils 63 and the rotor assembly 5, allowing airflow entering from the air inlet 21 to pass through the gaps and be discharged outward from the air outlet 22.

[0057] Please refer to Figure 4 , which is a schematic diagram of the air intake structure of the upper housing 2 of the brushless motor shown in an embodiment of the present application. 3-9 air inlets 21 are provided above the housing 1, and the air inlets 21 are evenly distributed around the circumference of the upper housing 2.

[0058] In one embodiment, six air inlets 21 are provided on the top of the housing 1. The air inlets 21 are evenly distributed on the side walls of the upper housing 2 of the motor around the axis, wherein the central angles of the two side edges of each air inlet 21 around the axis are equal. In addition, an installation guide is provided between the upper housing 2 and the stator assembly 6. When the upper housing 2 is installed in place, the air inlets 21 are relatively arranged corresponding to the gaps between the stator coils 63. Preferably, the air inlets 21 of the upper housing 2 are divided into three groups, with two air inlets 21 provided at every 120° central angle, and nine stator coils 63 are provided around the axis, with three stator coils 63 provided at every 120° central angle. When the upper housing 2 is installed in place, the two air inlets 21 of each group are exactly aligned with the two adjacent gaps between the three stator coils 63.

[0059] By setting the air inlet 21 close to the gap between the stator coil 63, on the one hand, the gas flow rate of the airflow passing through the gap between the stator coil 63 is relatively concentrated, thereby increasing the gas flow rate passing through the gap; on the other hand, the distance between the air inlet 21 and the heating position is shortened, thereby shortening the airflow path and further improving the heat dissipation efficiency.

[0060] Please refer to Figure 5 , which is a schematic diagram of the air guide structure of the lower housing 3 of the brushless motor shown in an embodiment of the present application. A centrifugal fan 4 is housed within the lower housing 3. Air outlets 31 are provided along the circumference of the lower housing 3, concentrated on one side, for outward airflow. Driven by the rotor assembly 5, the centrifugal fan 4 radially directs the airflow outward. The airflow is then rectified and combined by the inner wall of the lower housing 3 before being directed outward through the air outlets 31.

[0061] In one embodiment, the air guide surface of the air outlet 31 is smaller than the circumferentially integrated air guide surface of the air inlet 21. Six air inlets 21 are evenly distributed around the upper housing 2, while the air outlet 31 is concentrated on one on the lower housing 3. Furthermore, the angle formed between the two sides of the air outlet 31 and the motor axis is smaller than the sum of the angles formed between the two sides of the air guide area of ​​each air inlet 21 and the motor axis.

[0062] It can be understood that the air outlet 31 on the side wall of the lower shell 3 for concentrated air discharge can also be multiple air outlets 31 continuously concentrated together; or one air outlet 31 is set, but a diverter rib 34 is provided in the air guide area to separate the air outlet 31, wherein the diverter rib 34 is provided with a center angle of less than 5° relative to the motor axis to avoid the diverter rib 34 being too wide and forming a large impact wind noise with the airflow, so as to ensure that the airflow can have a larger flow rate when it is discharged from the cavity to the outside, and at the same time, the airflow can be dispersed after being discharged to achieve a noise reduction effect outside the noise reduction cavity.

[0063] Compared with setting multiple air outlets around the lower shell 3, the centralized rectification of the air outlet can reduce the wind noise inside the noise reduction chamber 7 while also significantly filtering out the superimposed noise generated by the wind wave interference between different air outlets 31 after the airflow overflows. Figure 9 As can be seen from the content, the wind noise generated by the centralized air outlet 31 is significantly reduced compared to the circumferential dispersed air outlet. The motors of existing motor-driven products are often wrapped in the base, which further blocks and weakens the motor noise. For example, when the external noise of existing food processing products is 75dB, the direct noise generated by the motor is often at least around 80dB to 85dB. After the motor's air outlet is centralized, when the angle ∅ between the two sides of the air guide area of ​​the air outlet 31 and the motor shaft meets the requirement of 10° to 120°, the motor's own noise can be maintained below 75dB, and the corresponding noise that can be diffused from the entire machine will be even smaller, improving the noise reduction effect of the motor itself and the overall product.

[0064] Further references Figure 10 Compared to the wind speed when the outlets 31 are dispersed circumferentially, the centralized arrangement of the outlets 31 not only reduces noise, but also significantly increases the actual wind speed between 20° and 140°. As can be seen, the airflow within the noise reduction chamber 7 is integrated through the outlets 31, making the airflow guidance within the chamber more stable and reducing the turbulent interference caused by excessive air outlets 31. Furthermore, directing the air outward after rectification also prevents the collision and obstruction of wind waves from different directions, accelerating the outward diffusion rate.

[0065] Preferably, the angle ∅ formed between the two sides of the air guide area of ​​the air outlet 31 and the motor shaft is 30° to 120°. Figure 9 and Figure 10 When the angle ∅ is greater than 120°, the wind noise generated will exceed 75dB, resulting in the noise reduction effect failing to meet expectations; in addition, considering the actual wind speed efficiency, when the angle ∅ is between 30° and 120°, the overall wind speed is higher than 3.5m / s. At this time, the heat dissipation efficiency of the entire noise reduction cavity 7 can be further improved, and even at high reverse speed (above 10,000rpm), the heat dissipation requirements can be met.

[0066] For further information, please refer to Figure 9 , the wind noise generated at the air outlet 31 gradually increases as the angle between the two sides of the air guide area increases. Preferably, the angle ∅ formed by the two sides of the air outlet 31 and the motor axis can be 40° to 100°, which can take into account the relative values ​​of thermal conductivity efficiency and air outlet noise. When the angle ∅ between the two sides of the air outlet 31 is less than 40°, although the wind noise generated will be relatively small, the overall air outlet flow rate efficiency will be relatively low, affecting the actual thermal conductivity efficiency; when the angle ∅ between the two sides of the air outlet 31 is greater than 100°, the air outlet 31 has a relatively high air guide and heat dissipation efficiency, and the wind noise is basically around 73dB and will not cause obvious noise interference to the human ear. When the angle ∅ is between 100° and 110°, although the noise will not fluctuate significantly, the actual thermal conductivity efficiency will decline significantly. When the angle ∅ is above 110°, the overall air outlet noise reduction effect and the air guide and heat dissipation effect will be relatively weak.

[0067] Please combine again Figure 6 and Figure 7 , which is a schematic diagram of the air guide structure of the air outlet 31 shown in an embodiment of the present application. The centrifugal fan 4 is accommodated in the lower housing 3, and the axial height of the guide blades of the centrifugal fan 4 can at least partially overlap with the air outlet 31, which can quickly guide the air in the noise reduction chamber 7 outward through the air outlet 31.

[0068] Preferably, the air outlet 31 is radially opposite to the centrifugal fan 4, and the axial height of the air outlet 31 is greater than that of the centrifugal fan 4. The air outlet 31 at least coincides with the height of the guide blade portion of the centrifugal fan 4 in the axial direction. It is understood that the guide blade portion of the centrifugal fan 4 is located on the upper end surface of the fan body, and the axial height of the air outlet 31 may cover the guide blade portion of the centrifugal fan 4 or the entire centrifugal fan 4. By limiting the relative position of the air outlet 31 and the centrifugal fan 4, smooth lateral airflow is ensured.

[0069] It is easy to imagine that the centrifugal fan 4 can also be set to cover the air outlet 31 at an axial height, and drive the air circulation through the guide blades and guide the air outward from the air outlet 31; or it can be set above the air outlet 31, and guide the air downward to the air outlet 31 through the fan body, and after the guide blades are thrown out, they are guided downward to the air outlet 31 through the side wall of the lower shell 3.

[0070] Preferably, the air outlet 31 is arranged to protrude outward relative to the inner wall of the lower shell 3. It can be understood that the arc radius of the air outlet 31 at the position of the lower shell 3 is larger than the arc radius of the inner wall of the lower shell 3 at other circumferential positions. By increasing the radial component at the position of the air outlet 31, the airflow can be quickly thrown outward by the action of centrifugal force when flowing through the air outlet 31, thereby avoiding excessive component of the airflow moving tangentially on the inner wall of the lower shell 3, resulting in direct passing through the air outlet 31 and continuous circulation and accumulation in the noise reduction chamber 7.

[0071] In one embodiment, a first guide wall 32 is provided on one side of the air outlet 31 along the reverse direction of the centrifugal fan 4 to guide the airflow outward. The distance between the first guide wall 32 and the motor axis gradually increases in the reverse direction until the end extends to the air guide area adjacent to the outwardly protruding air outlet 31. When the centrifugal fan 4 reverses and propels the airflow forward at high speed, the first guide wall 32 improves the continuity of the airflow's direction and reduces the wind noise caused by the sudden change in direction of the high-speed airflow.

[0072] It is understandable that the first guide wall 32 can be a guide arc surface or a bevel surface capable of rectifying the flow of gas in the noise reduction chamber 7. Preferably, the first guide wall 32 is a guide arc surface with a radius greater than the inner wall of the lower shell 3.

[0073] In another embodiment, the air outlet 31 is further provided with a second guide wall 33 on the side opposite to the first guide wall 32. When the high-speed airflow is not promptly directed outward after passing through the air outlet 31, it can continue to circulate along the second guide wall 33 back to the noise reduction chamber 7. Specifically, the first guide wall 32 and the second guide wall 33 have a gradually increasing guide curvature radius near the air outlet 31. That is, the curvature radius of the first guide wall 32 and the second guide wall 33 is the largest at the end position where they are connected to the air outlet 31. The airflow flowing tangentially is transferred through the second guide wall 33 and then integrated and re-enters the noise reduction chamber 7 for circulation and heat dissipation. This corrects the direction of the airflow that has been deviated outward by centrifugal force at the air outlet 31 to a direction consistent with the guide surface of the inner side wall of the lower shell 3, thereby preventing turbulence from forming at the air outlet 31, affecting the air circulation and generating large wind noise.

[0074] It can be understood that the first guide wall 32 can rectify and guide the airflow to be discharged, and the second guide wall 33 can collect, rectify and guide the airflow that cannot be discharged in time, thereby reducing the adverse effects of low air guide efficiency and high impact wind noise caused by the high-speed airflow flowing through the air outlet 31 during the reversal process.

[0075] Secondly, since the second guide wall 33 is arranged on the side of the air outlet 31 of the centrifugal fan 4 in the forward rotation direction, when the centrifugal fan 4 rotates forward to guide the air, the second guide wall 33 can also serve as an air guide surface for concentrating the air outlet 31, guiding the air flow to the air outlet 31 position protruding outward at the end.

[0076] Specifically, the average speed of the rotor assembly 5 during the forward driving process is relatively not less than the average speed during the reverse driving process. In fact, under the same driving speed, the airflow speed of the centrifugal fan 4 during the reverse driving is relatively faster. Based on this, the arc lengths of the first guide wall 32 and the second guide wall 33 can be adaptively set.

[0077] In one embodiment, the first guide wall 32 and the second guide wall 33 are relatively arranged on both sides of the air outlet 31, wherein the arc surface length of the first guide wall 32 on the reverse side is relatively larger than the second guide wall 33. Preferably, the guide section length of the first guide wall 32 does not exceed 1.5 times the length of the second guide wall 33, so that under different forward and reverse driving conditions, the air outlet 31 can ensure concentrated air outlet and relatively small wind noise, and the inside of the noise reduction cavity 7 can ensure sufficient circulation guide space.

[0078] It is understandable that the first guide wall 32 and the second guide wall 33 may also have equal guide arc lengths, but the central angle corresponding to the arc surface of the first guide wall 32 is greater than the central angle corresponding to the arc surface of the second guide wall 33.

[0079] In another embodiment, the first guide wall 32 and the second guide wall 33 may also be composed of a plurality of different guide arc surfaces or beveled surfaces, and the curvature radius corresponding to the guide surface relatively close to the air outlet 31 decreases step by step.

[0080] Please refer to Figure 8 The centrifugal fan 4 includes a plurality of guide blades 41 arranged symmetrically about the axis. A guide air duct 42 is formed radially between the centrifugal fan 4 and the inner wall of the lower housing 3. By defining the size relationship between the guide air duct 42 and the guide blades 41, the circulation and air guidance efficiency within the noise reduction chamber 7 can be further optimized.

[0081] Preferably, the channel width of the guide air duct 42 is not less than the guide width between adjacent guide blades 41, ensuring that the airflow radially outwardly directed by the centrifugal fan 4 can be rectified on the side, and then the guide blades 41 can be rotated to disturb the air laterally, thereby improving the lateral wind guide efficiency of the lower shell 3, and no axial flow deflection is required. This can reduce the overall height of the brushless motor and achieve flattening, and at the same time, can also achieve an increase in the flow rate of the concentrated air outlet 31.

[0082] In one embodiment, the guide blades 41 on the centrifugal fan 4 spirally diverge evenly outward around the center and extend to the edge of the centrifugal fan. The maximum outer diameter of the air guide area covered by the guide blades 41 is d1, the annular guide inner diameter of the inner wall of the lower shell 3 is d2, and the inner diameter of the arc surface at the air outlet 31 is d3, wherein d1<d2<d3, to ensure that there is a sufficient surrounding circulation guide cavity outside the guide blades 41, and the air can be promptly discharged outward at the air outlet 31.

[0083] Preferably, the outer diameter d1 of the guide blade 41 is 50-80 mm, the inner diameter d2 of the inner wall of the lower shell 3 is 60-100 mm, and the inner diameter d3 of the arc surface at the air outlet 31 is 90-100 mm.

[0084] It can be understood that the deflection side direction of the guide blade 41 extending along the radial spiral is opposite to the forward rotation direction of the motor shaft 51, and the airflow is guided backward relative to the rotation direction into the guide air duct 42 during the rotation process; similarly, the deflection side of the guide blade 41 is the same as the reverse driving direction, and the airflow is pushed forward along the rotation direction into the guide air duct 42 during the rotation process, so that the airflow can be quickly thrown out by centrifugal force under forward high-speed driving, and the airflow can be accelerated and pushed out of the guide blade during the reverse process at low speed driving.

[0085] Preferably, the outer diameter of the guide blade is d1, and the inner diameter of the inner wall of the lower shell is d2, wherein 0.6≤d1 / d2≤0.9.

[0086] Please refer to Figure 11It can be seen from the content that there is a mutually influencing correlation between the ratio of d1 and d2 and the air outlet speed, that is, when 0.6≤d1 / d2≤0.9 is satisfied, the air outlet speed inside the noise reduction chamber 7 has a peak value with the maximum actual air outlet efficiency, and the overall actual air outlet speed can basically be above 3.5m / s, and the overall air outlet efficiency is in the best state; when d1 / d2>0.9, the overall air outlet speed has a significant decline, which shows that the lateral surrounding guide air duct 42 of the centrifugal fan 4 has a positive promoting effect on the actual air outlet efficiency within the selected range, and the actual air outlet effect is significant; when d1 / d2<0.6, the guide air duct 42 air guide duct space is relatively too large relative to the guide fan blades 41, the air flow is relatively dispersed, and a stable flow direction cannot be formed, which on the one hand causes the overall air outlet and heat dissipation efficiency of the motor to be insufficient, and on the other hand, it also makes the overall volume of the brushless motor housing 1 too large, and the space utilization rate is significantly poor.

[0087] The guide blades 41 can be at least partially arranged opposite to the air outlet 31 in axial height, and the opening angle of the ends of adjacent guide blades 41 around the axis of the motor shaft 51 is a, and the opening angle of the air outlet 31 around the axis is b, where b is 2 to 15 times of a.

[0088] In another embodiment, the air outlet 31 can face between 2 and 15 guide blades 41, and the air outlet volume of the air outlet 31 and the guide blades 41 and the guide air duct 42 are matched. It can be understood that under high-speed air guide conditions, the air flow can be discharged smoothly to improve the heat dissipation effect, and the air flow pressure between the air outlet 31 and the guide blades 41 can also be decomposed to weaken the sharp air flow whistling sound.

[0089] In addition, please combine Figure 1 and Figure 2 The total area of ​​all air inlets of the air inlet 21 is S1, the total area of ​​conduction of the stator assembly 6 in the transverse cross-sectional gap is S2, and the conduction area of ​​the air outlet 31 is S3, satisfying S1>S2>S3, so that the interior of the shell 1 forms a stable flow-guiding shape that converges downward as a whole, avoiding the problem of interception of the stator assembly 6 in an "hourglass" shape from top to bottom.

[0090] In combination with the contents of the above embodiments, the brushless motor provided in this application may include a DC brushless motor, an inner rotor brushless motor, a direct-drive brushless motor, a variable frequency brushless motor, etc., which can be applied to the field of food processing technology, including common food processing machine types such as wall breakers, food processors, soy milk machines, and juicers. On the basis of meeting the flattening of the machine base or head, it can not only expand the forward and reverse driving functions, but also improve the performance of heat dissipation, noise reduction, and low noise reduction.

[0091] The above description is merely a preferred embodiment of the present application and is not intended to limit the present application. Various modifications and variations are possible for those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

Claims

1. A brushless motor with good noise reduction effect for a food processor, comprising a housing and a rotor assembly and a stator assembly disposed in the housing, characterized in that: The brushless motor is a flat brushless motor, and the shell is a flat shell. The shell includes an upper shell and a lower shell. The upper shell and the lower shell together form a noise reduction chamber surrounding the stator assembly. A centrifugal fan is provided in the noise reduction chamber, and the centrifugal fan is accommodated in the lower shell. The rotor assembly drives the centrifugal fan to rotate forward and reverse through forward and reverse driving. The side wall of the upper shell is provided with an air inlet, and the side wall of the lower shell is provided with an air outlet for concentrated air outlet. The inner wall of the lower shell is provided with a first guide wall on the reverse side of the air outlet, and the inner wall of the lower shell also includes a second guide wall provided on the forward side of the air outlet.

2. A brushless motor with good noise reduction effect for a food processor according to claim 1, characterized in that: The angle formed between the two sides of the air outlet and the motor axis is 30° to 120°.

3. A brushless motor with good noise reduction effect for a food processing machine according to claim 2, characterized in that: The angle formed by the two sides of the air outlet and the motor axis is 40° to 100°.

4. The brushless motor with good noise reduction effect for a food processing machine according to claim 1, characterized in that: The air outlet is arranged on the inner side wall of the lower shell body to protrude outward.

5. The brushless motor with good noise reduction effect for a food processing machine according to claim 4, characterized in that: The inner wall of the lower shell is provided with the first guide wall at the reverse side of the air outlet, the first guide wall having an increased distance relative to the motor axis, and the end of the first guide wall protrudes outward and extends to the air outlet.

6. The brushless motor with good noise reduction effect for a food processing machine according to claim 5, characterized in that: The first guide wall is a guide arc surface or a guide oblique surface for centrally rectifying the reversed airflow of the centrifugal fan.

7. The brushless motor with good noise reduction effect for a food processing machine according to claim 5, characterized in that: The guide curvature radius of the first guide wall and the second guide wall gradually increases on the side close to the air outlet.

8. The brushless motor with good noise reduction effect for a food processing machine according to claim 1, characterized in that: The centrifugal fan includes a plurality of guide blades symmetrically arranged around the axis, and the inner side wall of the lower shell also includes a guide air duct at least partially surrounding the centrifugal fan, and the width of the guide air duct is not less than the guide width between adjacent guide blades.

9. The brushless motor with good noise reduction effect for a food processing machine according to claim 8, characterized in that: The outer diameter of the guide blade is d1, and the inner diameter of the inner wall of the lower shell is d2, wherein 0.6≤d1 / d2≤0.

9.

10. The brushless motor with good noise reduction effect for a food processor according to claim 8, characterized in that: The central angle of the adjacent guide blade ends around the axis is a, and the central angle of the air outlet around the axis is b, where b is 2 to 15 times a.

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