Centrifugal fan, external rotor motor and electric tool

Abstract

A centrifugal fan (100), an external rotor motor and an electric tool, in a heat dissipation process, a fixing part (110) rotates along with starting of a motor body (200), drives blades (120) arranged in a circumferential direction to rotate, drives heat in the motor body to enter an air duct (130) along with airflow, and discharges the heat out of the centrifugal fan from the air duct, so as to realize heat dissipation of the motor body. The centrifugal fan is internally provided with the flow restraining part (140), and the flow restraining part is located at the end, back to the motor body, of the blade assembly, so that under restraining of the flow restraining part, airflow in the air channel is limited to flow to the side, back to the motor body, of the blade assembly, and the situation that backflow is formed, and the total air inlet amount in the motor body is affected is avoided. By means of the centrifugal fan, the airflow direction can be effectively improved, the total air inlet amount and the effective exhaust amount of airflow in the air channel are increased, the air inlet efficiency is improved, and the heat dissipation efficiency of a motor is improved.

Description

Centrifugal Fan, Outer Rotor Motor and Power Tool

[0001] The present invention relates to the technical field of heat dissipation devices, and particularly to a centrifugal fan, an outer rotor motor and a power tool.

[0002] A power tool is a device that uses an electric motor as a driving source to perform actions such as hammering, screwing, suction, etc., such as a screwdriver, a nail gun, a blower-sucker, etc. Its product performance depends to a large extent on the stable operation of the motor, and the stable operation of the motor depends on its own heat dissipation performance.

[0003] The heat dissipation structure of the motor is mainly divided into an axial flow fan and a centrifugal fan. Among them, the centrifugal fan uses centrifugal force to pressurize the axial air along the radial direction and then discharge it along the circumferential direction, and is widely used in outer rotor motors. However, due to the design defects of the traditional centrifugal fan structure, the air flow on the side of the centrifugal fan facing away from the motor will flow into the air duct from the opening on the side of the centrifugal fan facing away from the motor, reducing the total air intake volume and weakening the heat dissipation efficiency of the motor.

[0004]

[0005] Based on this, it is necessary to provide a centrifugal fan, an outer rotor motor and a power tool, which can effectively improve the air flow direction, increase the effective discharge volume of the air flow inside the air duct, and improve the heat dissipation efficiency of the motor.

[0006] A centrifugal fan is used to rotate under the drive of an outer rotor motor to dissipate heat from the outer rotor motor. The centrifugal fan includes: a fixing part, which is connected to the output shaft of the outer rotor motor and is used to rotate around the axis of the output shaft under the drive of the output shaft to drive the centrifugal fan to rotate; a blade assembly, including a plurality of blades, the plurality of blades are arranged at intervals around the axis of the output shaft and are driven by the fixing part to rotate around the axis of the output shaft, and an air duct for air flow to pass through is formed between adjacent two of the blades. The blade assembly includes an air inlet end facing the motor body of the outer rotor motor; the centrifugal fan further includes a flow inhibiting member, the flow inhibiting member is arranged on the fixing part and / or the blades and is located at one end of the blade assembly facing away from the motor body, and is used to prevent the air flow on the side of the blade assembly facing away from the motor body from flowing into the centrifugal fan; the ends of each of the blades away from the fixing part define a circular contour, the flow inhibiting member is configured as a circular structure, the center of the flow inhibiting member is concentric with the center of the circular contour, and the ratio range of the outer contour diameter d1 of the flow inhibiting member to the diameter d2 of the circular contour is 0.65-1.

[0007] In the above-mentioned motor, during the heat dissipation process, the fixing part rotates with the start of the motor body, driving the circumferentially arranged blades to rotate, forcing the heat in the motor body to enter the air duct from one side of the motor body along with the air flow, and discharging it outside the centrifugal fan from the air duct, so as to achieve the heat dissipation of the motor body. Since a flow restraining member is provided in the centrifugal fan, and the flow restraining member is located at one end of the blade assembly facing away from the motor body, therefore, under the restraint of the flow restraining member, the air flow on the side of the blade assembly facing away from the motor body is restricted from flowing into the centrifugal fan, avoiding the influence of the air flow flowing back into the centrifugal fan on the total air intake volume in the motor body. With such a design, through this centrifugal fan, the air flow direction can be effectively improved, the total air intake volume and the effective discharge volume of the air flow inside the air duct can be increased, and the air intake efficiency can be improved, so as to improve the motor heat dissipation efficiency.

[0008] In one embodiment, the flow restraining member includes a guiding surface facing the motor body, the guiding surface is arranged around the axial direction of the output shaft, and the guiding surface at least partially shields or covers one end of the blade assembly facing away from the motor body, for enabling part of the air flow to enter the air duct axially from the air inlet end and flow out of the air duct radially along the guiding surface.

[0009] In one embodiment, the flow restraining member is arranged on the fixing part, and the periphery of the flow restraining member extends out of the fixing part along the radial direction of the output shaft, and the part of the flow restraining member extending out of the fixing part is connected to each blade.

[0010] In one embodiment, the flow restraining member is a plate-like member, and in the radial direction of the output shaft, the thickness of one end of the plate-like member close to the output shaft is greater than the thickness of one end of the plate-like member far from the output shaft.

[0011] In one embodiment, in the radial direction of the output shaft, the thickness of the plate-like member remains unchanged from one end close to the output shaft to one end far from the output shaft.

[0012] In one embodiment, from one end close to the output shaft to one end far from the output shaft, the thickness change range of the flow restraining member is 6 mm to 1 mm.

[0013] In one embodiment, in the radial direction of the output shaft, the thickness of the blade increases from one end of the blade close to the output shaft to one end of the blade far from the output shaft.

[0014] In one embodiment, from one end of the blade close to the fixing part to one end of the blade far from the fixing part, the thickness change range of the blade is 1 mm to 3 mm.

[0015] In one embodiment, each of the blades includes a main body and a mounting portion. One end of the main body is connected to the fixing portion, and the end of the main body away from the fixing portion extends toward one side of the motor body to form a mounting portion. The centrifugal fan further includes a mounting ring, which includes a connecting ring and a mating portion with the connecting ring. The connecting ring is connected to the mounting portions of each of the blades, and the mating portion is used for mating with the motor body so that the motor body drives the centrifugal fan to rotate.

[0016] In one embodiment, a glue groove is formed on the surface of the mating portion for mating with the motor body, and the glue groove is used for filling glue.

[0017] In one embodiment, one of the mounting ring and the motor body is provided with a positioning protrusion, and the other is provided with a positioning groove.

[0018] In one embodiment, both the mounting ring and the flow suppressor are configured as circular structures. The inner contour diameter of the mounting ring is larger than the outer contour diameter of the flow suppressor, and the difference between the inner contour diameter of the mounting ring and the outer contour diameter of the flow suppressor is greater than or equal to 1 mm.

[0019] In one embodiment, the centrifugal fan further includes a plurality of reinforcing ribs arranged at intervals. The reinforcing ribs are arranged between adjacent blades, used for connecting adjacent blades, and covering at least part of the air outlet between adjacent blades.

[0020] An outer rotor motor includes the centrifugal fan according to any one of the above.

[0021] For the above-mentioned outer rotor motor using the above centrifugal fan, during the heat dissipation process, the fixing portion rotates with the start of the motor body, driving the circumferentially arranged blades to rotate, driving the heat in the motor body to enter the air duct with the air flow, and discharging it outside the centrifugal fan from the air duct to achieve the heat dissipation of the motor body. Since a flow suppressor is provided in the centrifugal fan and the flow suppressor is located at the end of the blade assembly facing away from the motor body, therefore, under the restraint of the flow suppressor, the air flow on the side of the blade assembly facing away from the motor body is restricted from flowing into the centrifugal fan, avoiding the air flow flowing back into the centrifugal fan from affecting the total air intake volume inside the motor body. Designed in this way, through this centrifugal fan, the air flow direction can be effectively improved, the total air intake volume and the effective discharge volume of the air flow inside the air duct can be increased, the air intake efficiency can be improved, and the motor heat dissipation efficiency can be improved.

[0022] A power tool includes the motor described above.

[0023] The above-mentioned power tool adopts the above centrifugal fan. During the heat dissipation process, the fixing part rotates with the startup of the motor body, driving the circumferentially arranged blades to rotate, driving the heat in the motor body to enter the air duct with the air flow, and discharging it outside the centrifugal fan from the air duct to achieve the heat dissipation of the motor body. Since a flow suppressing member is provided in the centrifugal fan and the flow suppressing member is located at one end of the blade assembly facing away from the motor body, therefore, under the restraint of the flow suppressing member, the air flow on the side of the blade assembly facing away from the motor body is restricted from flowing into the centrifugal fan, avoiding the influence of the air flow flowing back into the centrifugal fan on the total air intake volume in the motor body. With such a design, through this centrifugal fan, the air flow direction can be effectively improved, the total air intake volume and the effective discharge volume of the air flow inside the air duct can be increased, the air intake efficiency can be improved, and the motor heat dissipation efficiency can be improved.

[0024] The drawings forming a part of this application are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention.

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for use in the description of the embodiments. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0026] FIG. 1 is a perspective view of the structure of the centrifugal fan in some embodiments of the present application;

[0027] FIG. 2 is another perspective view of the structure of the centrifugal fan in some embodiments of the present application;

[0028] FIG. 3 is a cross-sectional view of the structure of the centrifugal fan in FIG. 2 along the A-A direction;

[0029] FIG. 4 is a schematic view of the back structure of the centrifugal fan in some embodiments of the present application;

[0030] FIG. 5 is a perspective view of the structure of the motor in some embodiments of the present application;

[0031] FIG. 6 is another perspective view of the structure of the motor in some embodiments of the present application;

[0032] FIG. 7 is a cross-sectional view of the structure of the motor in FIG. 6 along the B-B direction;

[0033] FIG. 8 is a vector diagram of the air flow movement of the centrifugal fan without a flow suppressing member in some embodiments of the present application;

[0034] FIG. 9 is a vector diagram of the air flow movement of the centrifugal fan with a flow suppressing member in some embodiments of the present application.

[0035] FIG. 10 is a schematic structural diagram of a centrifugal fan according to some other embodiments of the present application;

[0036] FIG. 11 is a schematic diagram of the noise distribution simulation of a centrifugal fan with and without a step in some embodiments of the present application;

[0037] FIG. 12 is an assembly structure of the mounting ring 150 and the blade 120 of the centrifugal fan in another example of the present application.

[0038] 100, centrifugal fan; 110, fixing part; 120, blade; 121, body; 122, mounting part; 123, circular profile; 130, air duct; 131, air inlet end; 132, axial opening; 133, radial opening; 140, flow suppression member; 141, guiding surface; 150, mounting ring; 151, positioning protrusion; 152, connecting ring; 153, mating part; 154, glue groove; 160, step; 170, reinforcing rib; 200, motor body; 210, output shaft; 220, stator; 230, rotor; 231, positioning groove.

[0039] To make the above objects, features, and advantages of the present invention more obvious and understandable, the following detailed description of the specific embodiments of the present invention will be given with reference to the accompanying drawings. Many specific details are set forth in the following description in order to fully understand the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the connotation of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.

[0040] In some embodiments, referring to FIGS. 1 and 5, a centrifugal fan 100 is used for dissipating heat from an external rotor motor, where the external rotor motor includes a motor body 200 and an output shaft 210. The output shaft 210 is driven by the motor body 200 and rotates around the axis of the output shaft 210. The centrifugal fan 100 includes a fixing part 110 and a blade assembly. The fixing part 110 is connected to the output shaft 210. The blade assembly includes a plurality of blades 120, and the plurality of blades 120 are spaced apart around the axis of the output shaft 210 on the fixing part 110. An air duct 130 for air flow is formed between two adjacent blades 120. The air duct 130 formed by the blade assembly further includes an air inlet end 131 facing the motor body 200, and air flows into the blades along the axis of the centrifugal fan 100 from the air inlet end 131 and is thrown away from the fan under the influence of centrifugal force. The centrifugal fan 100 further includes a flow suppression member 140. The flow suppression member 140 is disposed on the fixing part 110 and / or the blade 120 and is located at one end of the blade assembly facing away from the motor body 200 for suppressing the air flow on the side of the blade assembly facing away from the motor body 200 from flowing into the centrifugal fan 100.

[0041] Please refer to FIG. 4. The flow suppressor 140 is configured as a circular structure, and a circular contour 123 can be defined between the ends of the respective blades 120 away from the fixing portion 110. The center of the flow suppressor 140 is concentric with the center of the circular contour 123, and the ratio of the outer contour diameter d1 of the flow suppressor 140 to the diameter d2 of the circular contour 123 is 0.6 to 1. In this way, the diameter ratio between the blade 120 and the flow suppressor 140 is reasonably controlled, so that the air output of the centrifugal fan 100 is larger and more stable, thereby improving the heat dissipation efficiency of the motor.

[0042] It should be noted that the outer contour of the flow suppressor 140 should be understood as: the contour formed by the peripheral edge of the flow suppressor 140. In this embodiment, the flow suppressor 140 can be a complete circular structure. At this time, the outer contour diameter d1 is the diameter of the circular structure. Of course, the flow suppressor 140 can also be an annular structure. At this time, the outer contour diameter d1 is the outer diameter of the annular structure.

[0043] When the ratio between d1 and d2 is 0.65 to 1, the size ratio of the flow suppressor 140 will be appropriately increased, which is beneficial to further improving the air output of the centrifugal fan 100. For example: the ratio between d1 and d2 can be but is not limited to 0.65, 0.7, 0.8, 0.9, 0.98, 1, etc. When the ratio of d1 to d2 is less than 0.65, the size of the flow suppressor 140 is small, resulting in part of the air flow in the air duct 130 still being able to flow out from the opening formed between the adjacent blades 120 on the side facing away from the motor body to form a backflow, affecting the air intake of the air duct 130, and the improvement of the heat dissipation effect is not obvious. When the ratio of the outer contour diameter of the flow suppressor 140 to the outer contour diameter of the blade assembly reaches 0.65, the total air intake of the air duct 130 is significantly increased, and the heat dissipation effect is also improved accordingly. The larger the ratio between d1 and d2, the better the flow suppression effect. Preferably, the ratio range of d1 to d2 is 0.8 to 1. When the ratio between d1 and d2 is equal to 1, the flow suppression effect is the best. However, when the ratio of d1 to d2 is 1, since the size of the flow suppressor 140 is exactly the same as the size of the blade 120, it is difficult to demold the fan when manufacturing the centrifugal fan, and it is difficult to achieve in terms of process. Preferably, when the ratio between d1 and d2 reaches 0.8 to 0.9, the flow suppression effect and the process implementation difficulty can be effectively taken into account at the same time.

[0044] In the above-mentioned motor, during the heat dissipation process, the fixing part 110 rotates with the start of the motor body 200, driving the circumferentially arranged blades 120 to rotate, driving the heat in the motor body 200 to enter the air duct 130 with the air flow from the air inlet end 131 on the side facing the motor body 200, and discharging it out of the centrifugal fan 100 from the air duct 130, so as to achieve the heat dissipation of the motor body 200. Since the flow inhibitor 140 is provided in the centrifugal fan 100 and the flow inhibitor 140 is located at one end of the blade assembly facing away from the motor body 200, therefore, under the restraint of the flow inhibitor 140, the air flow on the side of the blade assembly facing away from the motor body 200 is restricted from flowing into the centrifugal fan 100, avoiding the air flow from flowing back into the air duct and affecting the total air intake in the motor body 200. In addition, setting the flow inhibitor 140 on the side of the blade assembly facing away from the motor body 200 can also prevent the air flow from forming a backflow on the side of the blade assembly facing away from the motor body 200, resulting in the air flow lingering in the air duct 130 and unable to be discharged. By setting the ratio of the diameter of the flow inhibitor 140 to the diameter of the circular contour of the blade assembly within a suitable range, the heat dissipation efficiency can be improved while reducing the difficulty of process implementation. Designed in this way, through the centrifugal fan 100, the air flow direction can be effectively improved, the total air intake and the effective discharge amount of the air flow inside the air duct 130 can be increased, and the air intake efficiency can be improved to improve the motor heat dissipation efficiency.

[0045] It should be noted that when the flow inhibitor 140 is not provided, most of the air flow in the air duct 130 will flow radially along the output shaft 210 under the action of centrifugal force to be discharged out of the centrifugal fan 100; however, since there is an axial opening 132 on the side of the blade assembly facing away from the motor body, the air flow passing through the air duct 130 will form a backflow at the opening on the side of the blade assembly facing away from the motor body. For an outer-rotor motor, since the clearance width for air intake between the stator 220 and the rotor 230 is relatively small, usually 0.5 mm to 1 mm, the centrifugal fan 100 is relatively sensitive to the backflow on the side of the blade assembly facing away from the motor body, resulting in a significant reduction in the total air intake at the air inlet of the air duct, greatly affecting the heat dissipation efficiency of the outer-rotor motor.

[0046] Therefore, the present application provides a flow inhibitor 140 in the centrifugal fan 100, and uses the flow inhibitor 140 to cover the axial opening 132 on the side of the centrifugal fan 100 facing away from the motor body 200, so that the air flow in the air duct is thrown out of the air duct along the flow inhibitor 140, effectively preventing the air flow from forming a backflow on the side of the centrifugal fan 100 facing away from the motor body 200, so as to increase the total air intake in the motor and increase the effective discharge amount of the air flow inside the air duct 130, thereby being beneficial to improving the heat dissipation efficiency of the outer-rotor motor.

[0047] Since the air inlet end 131 of the air duct 130 and the motor body 200 are both located on the same side of the centrifugal fan 100, that is, the air inlet end 131 of the air duct 130 is arranged facing the motor body 200; therefore, when the centrifugal fan 100 is started, the air flow enters the air duct 130 from one side of the motor body 200, so that the heat in the motor body 200 is easily brought into the air duct 130, which is beneficial to improving the heat dissipation effect of the motor.

[0048] In addition, there can be various designs for the implementation of the flow suppressing member 140 to prevent the air flow from flowing into the centrifugal fan 100 from the side of the blade assembly facing away from the motor body 200. For example: using the flow suppressing member 140 to cover or block the air outlet end of the air duct 130 in the axial direction of the fixing portion 110 (that is, the axial opening 132 between adjacent blades 120); or, designing the flow suppressing member 140 as a guiding structure such as a rotating impeller to actively guide the air flow in the air duct 130 to flow radially along the output shaft 210, etc.

[0049] For the convenience of understanding the axial direction of the output shaft 210 and the radial direction of the output shaft 210, taking Figure 2 as an example, the axial direction of the output shaft 210 is the direction indicated by any arrow of L1 in Figure 2; the radial direction of the output shaft 210 is the direction indicated by any arrow of L2 in Figure 2.

[0050] It should also be noted that in this embodiment, the number of blades 120 is not specifically limited, and its number can be determined according to the motor size or operating power. For example: for a large-size motor, the number of blades 120 can be designed to be more; for a small-size motor, the number of blades 120 is correspondingly less. For example: the number of blades 120 can be 12 to 33. Since this fan is a centrifugal fan 100, the outer contour diameter of the centrifugal fan 100 should be greater than or equal to the diameter of the motor body 200. Among them, the diameter of the motor body 200 can be 28mm to 80mm.

[0051] Furthermore, please refer to Figures 1 to 3. The flow suppressing member 140 includes a guiding surface 141 facing the motor body 200. The guiding surface 141 is arranged around the axial direction of the output shaft 210, and the guiding surface 141 at least partially covers or blocks one end of the blade assembly facing away from the motor body 200, and is used to make part of the air flow enter the air duct 130 axially from the air inlet end 131 and then flow out of the air duct 130 radially along the guiding surface 141. It can be seen that during the heat dissipation process, the air flow enters the air duct 130 from the axial direction of the centrifugal fan 100 through the air inlet end 131, and then flows out of the centrifugal fan 100 radially. Since the axial opening 132 is covered by the flow suppressing member 140, when the air flow entering the air duct 130 flows out of the axial opening 132, it will flow out radially along the guiding surface 141. Therefore, in this embodiment, the guiding surface 141 of the flow suppressing member 140 is used to guide the air flow to flow out of the air duct from the axial opening 132, prevent the air flow from forming a backflow at the back of the centrifugal fan 100 and affecting the air intake volume, and improve the heat dissipation efficiency.

[0052] It should be noted that the flow suppressor 140 can directly cover the axial opening 132 or form an obstruction at the axial opening 132. For example, the flow suppressor 140 is connected to both the fixing part 110 and the blade 120, so that the flow suppressor 140 is directly closed on the axial opening 132, preventing some air flow from flowing out of the axial opening 132; or, the flow suppressor 140 is arranged in the air duct 130 to form an obstruction at the axial opening 132; or, the flow suppressor 140 is connected to the fixing part 110 and arranged above the fixing part 110 and the blade 120, so that the flow suppressor 140 does not directly close the axial opening 132 but forms an obstruction to the axial opening 132. In this way, by using the blocking or covering method of the flow suppressor 140 on the axial opening 132, the air flow flows out of the air duct along the flow suppressor 140, effectively preventing the air flow from forming a backflow on the side of the blade assembly facing away from the motor body 200 and affecting the total air intake of the centrifugal fan 100.

[0053] One end of the air duct 130 in the radial direction of the output shaft 210 and away from the fixing part 110 can be defined as the radial opening 133. During the heat dissipation process, the air flow enters the air duct 130 axially from the air inlet end 131 of the centrifugal fan 100 and then flows out of the centrifugal fan 100 radially from the radial opening 133.

[0054] It should also be noted that the flow suppressor 140 can be a complete circular structure or an annular structure. When the flow suppressor 140 is a complete circular structure, it will completely cover the fixing part 110, and the periphery (i.e., the edges around) of the flow suppressor 140 extends beyond the fixing part 110 and covers or blocks at least a part of each axial opening 132. When the flow suppressor 140 is an annular structure, the flow suppressor 140 is arranged around the fixing part 110 and connected to the blade assembly.

[0055] In addition, the flow suppressor 140 can be concentrically arranged on the fixing part 110 or eccentrically arranged. At the same time, the periphery of the flow suppressor 140 can cover at least a part of the axial opening 132 or completely cover the axial opening 132. It can be understood that the larger the ratio of the outer contour diameter d1 of the flow suppressor 140 to the diameter d2 of the circular contour of the blade assembly, the larger the area of the axial opening 132 covered by the flow suppressor 140 and the better the flow suppression effect.

[0056] Optionally, the connection method between the flow suppressor 140 and the fixing part 110 can be but is not limited to bolt connection, welding, bonding, pin connection, riveting, integral molding method, etc. Among them, the integral molding method can be injection molding, die casting, extrusion, etc.

[0057] Furthermore, please refer to FIG. 1. The flow restrictor 140 is provided on the fixing portion 110, and the periphery of the flow restrictor 140 extends out of the fixing portion 110 along the radial direction of the output shaft 210. The portion of the flow restrictor 140 extending out of the fixing portion 110 is connected to each blade 120. In this embodiment, the connection manner of the flow restrictor 140 with the fixing portion 110 and each blade 120 can be integrally formed. Such a design not only helps to improve the overall structural strength of the centrifugal fan 100, but also helps to improve the airtightness between the flow restrictor 140 and the blades 120, and prevent the air flow on the side of the blade assembly facing away from the motor body 200 from flowing into the centrifugal fan 100 through the gap between the flow restrictor 140 and the blades 120.

[0058] In some embodiments, please refer to FIG. 3. The flow restrictor 140 is a plate-like member. In the radial direction of the output shaft 210, the thickness of the plate-like member at the end close to the output shaft 210 (i.e., connected to the fixing portion) is greater than the thickness of the plate-like member at the end far from the output shaft 210. That is, the guide surface 141 has a certain slope from the inside to the outside in the radial direction of the output shaft 210, so that when the air flow on the guide surface 141 changes from axial flow to radial flow, the air outlet resistance of the air flow can be reduced, which is beneficial to increasing the total air intake volume in the motor. After testing, compared with the structure where the guide surface 141 is a flat surface, the structure where the guide surface 141 is an arc surface can increase the total air volume of the centrifugal fan by 174%.

[0059] It should be noted that the inclination angle of the guide surface 141 can have various values. For example, the inclination angle α between the guide surface 141 and the plane perpendicular to the axis of the output shaft 210 can be 0° to 5°.

[0060] Specifically, please refer to FIG. 1. In the radial direction of the output shaft 210, the thickness h of the flow restrictor 140 gradually decreases from the middle of the flow restrictor 140 (i.e., the end of the flow restrictor 140 close to the output shaft) to the periphery of the flow restrictor 140 (i.e., the end of the flow restrictor 140 far from the output shaft), that is, the flow restrictor 140 gradually becomes thinner from the inside to the outside. The thickness change range of the flow restrictor 140 from the middle to the edge is 6 mm to 1 mm. For example: the middle thickness h of the flow restrictor 140 is 6 mm; the edge thickness h of the flow restrictor 140 is 1 mm; or, the middle thickness h of the flow restrictor 140 is 5.5 mm; the edge thickness h of the flow restrictor 140 is 2 mm; or, the middle thickness h of the flow restrictor 140 is 2.9 mm; the edge thickness h of the flow restrictor 140 is 1.2 mm.

[0061] In another embodiment, in the radial direction of the output shaft 210, the thickness h of the flow restrictor remains unchanged from the end close to the output shaft 210 to the end far from the output shaft 210, that is, the flow restrictor 140 has a uniform thickness. For example: the thickness h of the flow restrictor 140 is 1.2 mm, or 2 mm.

[0062] The heat dissipation efficiency of a centrifugal fan without the flow inhibitor 140 and the centrifugal fan 100 with the flow inhibitor 140 is compared through experimental data below. The centrifugal fan 100 without the flow inhibitor 140 and the centrifugal fan 100 of this embodiment are respectively analyzed for the airflow movement through Computational Fluid Dynamics (CFD). For details, please refer to FIGS. 8 and 9. For ease of explanation, the air inlet area of the centrifugal fan 100 is represented by a dashed box S1, the air outlet area of the centrifugal fan 100 is represented by a dashed box S2, and the back side of the centrifugal fan 100 is represented by a dashed box S3; while the recirculation part is represented by a dashed box S4. FIG. 8 is an airflow movement analysis diagram of the centrifugal fan 100 without the flow inhibitor 140, and FIG. 9 is an airflow movement analysis diagram of the centrifugal fan 100 with the flow inhibitor 140. Obviously, the airflow of the centrifugal fan 100 without the flow inhibitor 140 will form a recirculation at the back side of the centrifugal fan 100 (i.e., the area S4 in FIG. 8), resulting in a reduction in the total air inlet volume and air outlet volume of the centrifugal fan 100. After the flow inhibitor 140 is provided, the recirculation is significantly reduced, effectively preventing the airflow on the side of the blade assembly facing away from the motor body 200 from flowing into the centrifugal fan 100, effectively increasing the air outlet volume and the total air inlet volume, thereby being beneficial to improving the motor heat dissipation efficiency.

[0063] In some embodiments, please refer to FIG. 10. In the radial direction of the output shaft 210, the thickness of the blade 120 is denoted as D, and the thickness D shows an increasing trend from the end of the blade 120 close to the output shaft 210 to the end of the blade 120 far from the output shaft 210. Herein, "showing an increasing trend" means that the overall change trend of the thickness D is increasing, that is, the thickness of the blade 120 is thinner at the end close to the output shaft 210; while it is thicker at the end far from the output shaft 210. For example: first gradually increasing; then, remaining unchanged or suddenly increasing and then decreasing; later, gradually increasing again, etc. At the end close to the output shaft 210, the thickness of the blade 120 is designed to be thinner, aiming to increase the gap between adjacent two blades 120 and improve the air inlet volume; at the end far from the output shaft 210, the thickness of the blade 120 is designed to be thicker, aiming to enhance the structural strength of the blade 120. Of course, in some other embodiments, the thickness of the blade 120 may also remain consistent from the end of the blade 120 close to the output shaft 210 to the end of the blade 120 far from the output shaft 210.

[0064] As an example, the thickness of the blade 120 can be designed to change uniformly. Specifically in some embodiments, the thickness D gradually increases (or increases uniformly) from the end of the blade 120 close to the output shaft 210 to the end of the blade 120 far from the output shaft 210. In this way, by using the uniform change of the thickness, the air inlet efficiency is better.

[0065] As another example, the thickness of the blade 120 can also be designed to vary non-uniformly. Specifically, a step 160 structure or the like is provided on the blade 120. In this example, a centrifugal fan with a step 160 structure on the air guiding side surface 124 and a centrifugal fan 100 with a uniformly varying thickness of the blade 120 are respectively assembled to the outer rotor motor for air volume and noise tests. The results can be referred to Table 1 and Figure 11. In Figure 11, (a) is a schematic diagram of the noise distribution simulation of the centrifugal fan with the step 160; (b) in Figure 11 is a schematic diagram of the noise distribution simulation of the centrifugal fan without the step 160 (i.e., the centrifugal fan 100 with a uniformly varying thickness of the blade 120); Table 1 is the total air volume of the centrifugal fan with the step and the centrifugal fan of the present application.

[0066] Table 1

[0067] As can be seen from Table 1, the total air volume of the centrifugal fan with the step 160 structure is 0.38 L / S less than that of the centrifugal fan 100 with a uniformly varying thickness of the blade 120, that is, the total air volume of the centrifugal fan with a uniformly varying thickness of the blade 120 can be increased by 9.5%. At the same time, it should be explained that the internal air volume of the motor and the external air volume of the motor should be understood as follows: there is a relatively large gap between the rotor 230 and the motor housing. When the centrifugal fan 100 operates, a part of the air flow passes through the internal air passage of the rotor 230 to dissipate heat from the stator 220 of the motor; another part of the air flow passes through the external air passage of the rotor 230, and the heat dissipation effect of this part of the air flow on the stator 220 is not significant. Therefore, this part of the air passage should be minimized during design.

[0068] In addition, as can be seen from Figure 11(a) and Figure 11(b), the maximum value of the noise generated by the centrifugal fan 100 with a uniformly varying thickness of the blade 120 is 2 dB lower than the maximum value of the noise generated by the centrifugal fan with the step 160 structure.

[0069] In some embodiments, the blade 120 is also provided with a demolding angle in the radial direction of the output shaft 210. For example, the demolding angle can be 0.5° to 1°, which is convenient for the integral molding and demolding of the blade 120 and improves the product molding rate.

[0070] In some embodiments, please refer to Figure 1. Each blade 120 includes a main body 121 and a mounting portion 122. One end of the main body 121 is connected to the fixing portion 110, and the end of the main body 121 away from the fixing portion 110 extends toward the side of the motor body 200 to form the mounting portion 122. With such a design, by rotating the blade 120, the air flow in the air duct 130 exits more smoothly and the air output volume is larger.

[0071] As shown in FIGS. 1 and 2, in one example, the centrifugal fan 100 further includes a mounting ring 150. The mounting ring 150 is connected to the mounting portions 122 of each blade 120, and the mounting portions 122 of each blade 120 extend and are connected to the side surface of the mounting ring 150. The mounting ring 150 is mated with the motor body 200 so that the motor body 200 drives the centrifugal fan 100 to rotate. In this way, by mating the mounting ring 150 with the motor body 200, the centrifugal fan 100 is stably mounted on the motor body 200, ensuring the stable rotation of the centrifugal fan 100.

[0072] In another example, the structure of the mounting ring 150 is different from that of the mounting ring 150 in the previous example. As shown in FIG. 12, the mounting ring 150 includes a connecting ring 152 and a mating portion 153 connected to the connecting ring 152. The connecting ring 150 is located between the blade assembly and the mating portion 153. The connecting ring 150 is used to connect the mounting portions 122 of each blade 120, that is, the bottoms of the mounting portions 122 of each blade are connected to the connecting ring 152. The mating portion 153 is used to mate with the motor body 121. The mounting ring 150 in the previous example connects the blade 120 through a ring surface, and the bottoms of each blade 120 are exposed. Compared with the structure of the mounting ring 150 in the previous example, the mounting ring provided in this example has a connecting ring 152, and the bottom of the blade 120 is connected through the connecting ring 152, thereby improving the overall strength of the blade assembly. Optionally, the connection manner between the mounting ring 150 (or the connecting ring 152) and the blade 120 may be, but is not limited to, bolt connection, welding, bonding, pin connection, riveting, integral molding, etc. Preferably, in this example, the connecting ring 152, the mating portion 153 and the blade are integrally formed and connected. Thus, the mounting ring 150 is not only a connecting member for connecting the blade 120 and the motor, but also a torque transmission member between the blade 120 and the motor. When the motor rotates, the torque is transmitted to the mounting ring 150, and the mounting ring 150 is integrally formed with the blade 120, so that the torque can be directly transmitted to the blade 120. Such a setting can reduce the use of torque transmission members, reduce the assembly steps, and at the same time reduce the overall volume of the motor and the fan.

[0073] It should be noted that the mating of the mounting ring 150 with the motor body 200 can enable the motor body 200 to drive the centrifugal fan 100 to rotate. For example, taking an outer rotor motor as an example, the mounting ring 150 (or the mating portion 153) is first mated with the rotor 230 of the motor, and then the stator housing is sleeved outside the mounting ring 150 (or the mating portion 153). The rotation of the rotor 230 drives the mounting ring 150 to rotate, and further realizes the rotation of the centrifugal fan 100, etc. In addition, after the mounting ring 150 rotates, the mounting ring 150 can drive the output shaft 210 to rotate through the fixing portion 110 or the blade 120, etc.

[0074] Generally, the toroidal surface of the mating part 153 is a smooth toroidal surface. When the mating part 153 is mated with the stator housing, first apply glue to the outer surface of the fitting part 152, and then sleeved the stator housing on the outer surface of the mating part 153. The centrifugal fan and the motor are fixed together through the interference fit and the adhesiveness of the glue. However, during the assembly process, since the surface of the supply part 152 is a smooth surface, during the process of sleeving the stator housing, the stator housing will scrape off the glue on the surface of the mating part 153, resulting in almost no glue residue on the surface of the mating part 153. Furthermore, the centrifugal fan and the motor are only combined through the interference force, resulting in poor assembly effect and low service life.

[0075] In this example, as shown in FIG. 12, a glue groove 154 is provided on the outer surface of the mating part 153. When the mating part 153 is mated with the stator housing, first apply glue to the outer surface of the fitting part 152, and then sleeved the stator housing on the outside of the mating part 153. During the assembly process, the stator housing is installed to the outside of the mounting ring 150 along the assembly direction shown in FIG. 12. During the assembly process, the stator housing will squeeze the glue on the outer surface of the supply part 152 into the glue groove 154. Thus, the glue filled in the glue groove 154 can adhere the stator housing and the mounting ring 150, so that the centrifugal fan and the motor are combined through the interference force and the adhesiveness of the glue, and the assembly is more compact. Experiments show that when the glue groove 154 is not provided on the surface of the mating part 153, the centrifugal fan will be separated from the motor after continuously working for 25 hours. When the glue groove 154 is provided on the surface of the mating part 153, the centrifugal fan can continuously work for at least 300 hours, greatly improving the service life of the centrifugal fan.

[0076] In this example, the glue groove 154 includes a transverse glue groove and a longitudinal glue groove. The mating part 153 is cylindrical, wherein the transverse glue groove 154 extends along the circumferential direction of the mating part 153, and the longitudinal glue groove extends along the height direction of the mating part 153. The number of the glue grooves 154 in this embodiment is not limited, and the number of the glue grooves 154 can be set according to the size of the mating part 153.

[0077] Furthermore, please refer to FIGS. 1 and 7. Among the mounting ring 150 and the motor body 200, a positioning protrusion 151 is provided on one of them, and a positioning groove 231 is provided on the other. That is, the mounting ring 150 may be provided with the positioning protrusion 151, and the motor body 200 is provided with the positioning groove 231; or, the mounting ring 150 may also be provided with the positioning groove 231, and the motor body 200 is provided with the positioning protrusion 151. During assembly, the positioning protrusion 151 is inserted into the positioning groove 231 to realize the positioning installation between the mounting ring 150 and the motor body 200. Specifically, in some embodiments, in the motor body 200, the positioning protrusion 151 or the positioning groove 231 is provided on the rotor 230 of the motor body 200.

[0078] Specifically, please refer to FIG. 1. The positioning protrusions 151 are provided on the mounting ring 150. At the same time, there are multiple positioning protrusions 151, and the multiple positioning protrusions 151 are arranged at intervals along the circumferential direction of the mounting ring 150. In addition, when the motor body 200 is an outer rotor motor, the positioning groove 231 is the clearance groove between the magnetic steels of two adjacent rotors 230.

[0079] In some embodiments, please refer to FIGS. 3 and 4. The mounting ring 150 and the flow suppressor 140 are both configured as circular structures. The inner contour diameter d3 of the mounting ring 150 is greater than the outer contour diameter d1 of the flow suppressor 140, and the difference between the inner contour diameter d3 of the mounting ring 150 and the outer contour diameter d1 of the flow suppressor 140 is greater than or equal to 1 mm. Exemplarily, the difference between the inner contour diameter d3 of the mounting ring 150 and the outer contour diameter d1 of the flow suppressor 140 is 1 mm, or 1.2 mm, or 1.5 mm. Of course, the difference between the inner contour diameter d3 of the mounting ring 150 and the outer contour diameter d1 of the flow suppressor 140 cannot be too large, and it is also necessary to ensure that the ratio range of the outer contour diameter d1 of the flow suppressor 140 to the circular contour diameter d2 of the blade assembly is greater than or equal to 0.6. With such a design, there is a gap between the flow suppressor 140 and the mounting ring 150, which facilitates the demolding of the centrifugal fan 100 and is conducive to improving the product molding yield.

[0080] In some embodiments, as shown in FIG. 12, the centrifugal fan 100 further includes a plurality of reinforcing ribs 170 arranged at intervals. The reinforcing ribs 170 are disposed between two adjacent blades 120, connect the two adjacent blades 120, and the reinforcing ribs 170 fill part of the radial openings 132. By providing the reinforcing ribs 170, the strength of the blade assembly can be improved.

[0081] It should be noted that generally, the more the number of blades 120, the greater the wind speed of the centrifugal fan 100 and the better the heat dissipation effect. However, the size of the centrifugal fan is limited. When the number of blades 120 is more, in order to ensure that the size of the mirror openings 132 (i.e., the air outlets) between adjacent blades 120 is not affected and the air outlet effect is not affected, the thickness of the blades 120 will be reduced, which will in turn lead to a reduction in the strength of the blades 120. In this embodiment, by providing the reinforcing ribs 170 between two adjacent blades 120, both sides of the reinforcing ribs 170 are respectively connected to two adjacent blades 120, and the bottom is connected to the connecting ring 152 of the mounting ring 150, so that the reinforcing ribs 170, the blades 120 and the mounting ring 150 are integrated, and the strength of the blade assembly 120 can be improved.

[0082] The number of the reinforcing ribs 170 can be set according to the number of the blades 120. The number of the reinforcing ribs 170 is less than that of the blades 120, and multiple reinforcing ribs 170 can be evenly distributed between the blade assemblies 120. For example, when the number of the blades is 25, the number of the reinforcing ribs 170 can be set to 5, and the 5 reinforcing ribs 170 are evenly distributed; or when the number of the blades is 30, the number of the reinforcing ribs 170 can be set to 6, and the 6 reinforcing ribs 170 are evenly distributed.

[0083] For the above centrifugal fan, by arranging the reinforcing ribs 170 between adjacent blades, the strength of the blades 120 can be improved when the number of the blades 120 increases, so as to improve the service life of the centrifugal fan 100 without affecting the heat dissipation effect.

[0084] In some embodiments, an external rotor motor includes the centrifugal fan 100 described in any one of the above.

[0085] Wherein, the diameter of the centrifugal fan 100 is equal to the diameter of the external rotor motor 230. And since the flow suppressor 140, the blades 120 and the mounting ring 150 of the centrifugal fan 100 are integrally formed, when assembling the centrifugal fan 100 and the external rotor motor 230, the mounting ring 150 can not only connect the connecting piece of the blade 120 and the motor, but also serve as a torque transmission piece between the blade 120 and the motor. When the motor rotates, the torque is transmitted to the mounting ring 150, and the mounting ring 150 and the blade 120 are integrally formed, so that the torque can be directly transmitted to the blade 120. Compared with the traditional external rotor motor, the external rotor motor of this embodiment can reduce the use of torque transmission pieces, reduce the assembly steps, and at the same time, by setting the outer contour diameter of the fan blade assembly to be equal to the outer contour diameter of the motor and reducing the use of torque transmission pieces, the overall volume of the motor and the fan can also be reduced.

[0086] The above-mentioned outer rotor motor 230 uses the above-mentioned centrifugal fan 100. During the heat dissipation process, the fixing part 110 rotates with the start of the motor body 200, driving the circumferentially arranged blades 120 to rotate, driving the heat in the motor body 200 to enter the air duct 130 along with the air flow, and discharging it out of the centrifugal fan 100 from the air duct 130 to achieve heat dissipation of the motor body 200. Since the flow restricting member 140 is provided in the centrifugal fan 100 and the flow restricting member 140 is located at one end of the blade 120 assembly facing away from the motor body 200, therefore, under the restraint of the flow restricting member 140, the air flow in the air duct 130 is restricted from forming a backflow on the side of the blade 120 assembly facing away from the motor body 200, avoiding the backflow from affecting the total air intake volume in the motor body 200. Designed in this way, through this centrifugal fan 100, the air flow direction can be effectively improved, the total air intake volume and the effective discharge volume of the air flow inside the air duct 130 can be increased, and the air intake efficiency can be improved to improve the motor heat dissipation efficiency. Therefore, the motor provided in this embodiment not only has a centrifugal fan with a small volume, but also has a good heat dissipation effect of the centrifugal fan and a high heat dissipation efficiency of the motor.

[0087] In some embodiments, referring to FIG. 5, the motor body 200 further includes a stator 220 and a rotor 230. The stator 220 includes a yoke and a coil winding, and the rotor 230 includes a rotor frame and a permanent magnet. The outer rotor motor is a device in which the rotor 230 is sleeved outside the stator 220, so that the rotor 230 rotates externally.

[0088] Referring to FIGS. 6 and 7, when the motor body 200 is an outer rotor 230 motor, the output shaft 210 is rotatably connected to the stator 220. The fixing part 110 is rotatably sleeved on the output shaft 210. The rotor 230 is connected to the centrifugal fan 100 so that the centrifugal fan 100 rotates together with the rotor 230.

[0089] In some embodiments, a power tool includes the outer rotor motor in the above embodiments. Among them, the power tool can be a chain saw, a pruning machine, a lawn mower, etc.

[0090] The above-mentioned power tool adopts the above-mentioned outer-rotor motor. During the heat dissipation process, the fixing part 110 rotates with the start of the motor body 200, driving the circumferentially arranged blades 120 to rotate, driving the heat in the motor body 200 to enter the air duct 130 along with the air flow, and discharging it from the air duct 130 outside the centrifugal fan 100, so as to realize the heat dissipation of the motor body 200. Since the flow inhibitor 140 is arranged in the centrifugal fan 100, part of the air flow entering the air duct 130 will be restricted by the flow inhibitor 140 from flowing to the side of the centrifugal fan 100 opposite to the motor body 200, that is, reducing the air output on the back side of the centrifugal fan 100, and avoiding the formation of a backflow on the back of the centrifugal fan 100, resulting in the air flow lingering in the air duct 130 and unable to be effectively discharged. With such a design, through the centrifugal fan 100, the air flow direction can be effectively improved, the effective discharge volume of the air flow inside the air duct 130 can be increased, and the motor heat dissipation efficiency can be improved. Moreover, since the outer-rotor motor and the centrifugal fan 100 of the present application are small in volume, when the internal space of the power tool is limited, although the traditional axial flow fan has a good heat dissipation effect, its volume is relatively large, and it is restricted by the internal space of the power tool and cannot be installed. However, for the centrifugal fan 100 provided in the present application, by arranging the flow inhibitor 140 on the back of the blade assembly, the heat dissipation effect of the centrifugal fan 100 can be effectively improved. In addition, the centrifugal fan 100 is simply assembled with the motor, small in volume and occupying little space, which is beneficial to the miniaturized design of the power tool main body.

[0091] It should be noted that the power tool can be, but is not limited to, a screwdriver, a nail gun, a blower-sucker, etc.

[0092] The technical features of the above embodiments can be combined arbitrarily. For the sake of concise description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0093] The above embodiments only represent several implementation manners of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the invention patent. It should be pointed out that for those of ordinary skill in the art, without departing from the concept of the present invention, several deformations and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the invention patent should be subject to the appended claims.

[0094] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present invention.

[0095] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of such features. In the description of the present invention, the meaning of "a plurality" is at least two, such as two, three, etc., unless otherwise specifically and clearly defined.

[0096] In the present invention, unless otherwise clearly defined and limited, the terms "mounted", "connected", "coupled", "fixed", etc. shall be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or integrated; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the internal communication of two elements or the interaction relationship between two elements, unless otherwise clearly limited. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0097] In the present invention, unless otherwise clearly defined and limited, the first feature being "on" or "under" the second feature may be that the first and second features are in direct contact, or the first and second features are indirectly in contact through an intermediate medium. Moreover, the first feature being "above", "over" and "on top of" the second feature may be that the first feature is directly above or obliquely above the second feature, or merely indicates that the first feature has a higher horizontal height than the second feature. The first feature being "under", "beneath" and "underneath" the second feature may be that the first feature is directly below or obliquely below the second feature, or merely indicates that the first feature has a lower horizontal height than the second feature.

[0098] It should be noted that when an element is referred to as "fixed to" or "disposed on" another element, it can be directly on the other element or there may also be an intermediate element. When an element is considered to be "connected" to another element, it can be directly connected to the other element or there may be an intermediate element at the same time. The terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used in this article are only for illustrative purposes and do not represent the only implementation.

Claims

A centrifugal fan is used to rotate under the drive of an outer rotor motor to dissipate heat from the outer rotor motor. It is characterized in that the centrifugal fan includes: a fixing part, which is connected to the output shaft of the outer rotor motor and is used to rotate around the axis of the output shaft under the drive of the output shaft to drive the centrifugal fan to rotate; a blade assembly, including a plurality of blades, the plurality of blades are arranged at intervals around the axis of the output shaft and are driven by the fixing part to rotate around the axis of the output shaft, and an air duct for air flow is formed between two adjacent blades, and the blade assembly includes an air inlet end facing the motor body of the outer rotor motor; the centrifugal fan further includes a flow suppression member, which is arranged on the fixing part and / or the blades and is located at one end of the blade assembly facing away from the motor body, and is used to prevent the air flow on the side of the blade assembly facing away from the motor body from flowing into the centrifugal fan; the ends of each blade away from the fixing part define a circular contour, the flow suppression member is configured as a circular structure, the center of the flow suppression member is concentric with the center of the circular contour, and the ratio range of the outer contour diameter d1 of the flow suppression member to the diameter d2 of the circular contour is 0.65-1. The centrifugal fan according to claim 1 It is characterized in that the flow suppression member includes a guiding surface arranged facing the motor body, the guiding surface is arranged around the axial direction of the output shaft, and the guiding surface at least partially shields or covers one end of the blade assembly facing away from the motor body, and is used to make part of the air flow enter the air duct axially from the air inlet end and then flow out of the air duct radially along the guiding surface. The centrifugal fan according to claim 2 It is characterized in that the flow suppression member is arranged on the fixing part, and the periphery of the flow suppression member extends out of the fixing part along the radial direction of the output shaft, and the part of the flow suppression member extending out of the fixing part is connected to each blade. The centrifugal fan according to claim 3 It is characterized in that the flow suppression member is a plate-like member, and in the radial direction of the output shaft, the thickness of the plate-like member at the end close to the output shaft is greater than the thickness of the plate-like member at the end far from the output shaft; or, in the radial direction of the output shaft, the thickness of the plate-like member remains unchanged from the end close to the output shaft to the end far from the output shaft. The centrifugal fan according to claim 4 It is characterized in that from the end close to the output shaft to the end far from the output shaft, the thickness change range of the flow suppression member is 6mm-1mm. The centrifugal fan according to claim 1 It is characterized in that in the radial direction of the output shaft, the thickness of the blade increases from the end of the blade close to the output shaft to the end of the blade far from the output shaft. The centrifugal fan according to claim 6 It is characterized in that from the end of the blade close to the fixing part to the end of the blade far from the fixing part, the thickness change range of the blade is 1mm-3mm. The centrifugal fan according to claim 1 It is characterized in that Each of the blades includes a main body and a mounting portion. One end of the main body is connected to the fixing portion, and the end of the main body away from the fixing portion extends toward one side of the motor body to form the mounting portion. The centrifugal fan further includes a mounting ring, which includes a connecting ring and a mating portion with the connecting ring. The connecting ring is connected to the mounting portions of all the blades, and the mating portion is used to mate with the motor body so that the motor body drives the centrifugal fan to rotate. The centrifugal fan according to claim 8, characterized in that, a glue groove is formed on the surface of the mating portion for mating with the motor body, and the glue groove is used to fill glue. The centrifugal fan according to claim 8, characterized in that, one of the mounting ring and the motor body is provided with a positioning protrusion, and the other is provided with a positioning groove. The centrifugal fan according to claim 8, characterized in that, the mounting ring and the flow suppressor are both configured as circular structures. The inner contour diameter of the mounting ring is larger than the outer contour diameter of the flow suppressor, and the difference between the inner contour diameter of the mounting ring and the outer contour diameter of the flow suppressor is greater than or equal to 1 mm. The centrifugal fan according to claim 1, characterized in that, the centrifugal fan further includes a plurality of reinforcing ribs arranged at intervals. The reinforcing ribs are arranged between adjacent two blades, used to connect adjacent two blades, and cover at least part of the air outlet between adjacent two blades. An outer rotor motor, characterized in that, it includes the centrifugal fan according to any one of claims 1-12. A power tool, characterized in that, it includes the outer rotor motor according to claim 12.

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