Centrifugal wind wheel and electric tool

Abstract

The utility model discloses a centrifugal wind wheel and an electric tool, the centrifugal wind wheel comprises a chassis and a plurality of blades, the chassis is used for being fixedly connected with a driving shaft, and the driving shaft drives the chassis to rotate so as to drive the plurality of blades to rotate. The chassis is provided with a first side and a second side which are oppositely arranged in the axial direction. The blades are arranged on the first side and distributed at intervals in the circumferential direction, each blade extends from the inner circumference of the base plate to the outer circumference and is provided with an air inlet end relatively close to the center of the base plate and an air outlet end relatively away from the center of the base plate, and the air outlet ends of at least part of the blades extend to exceed the outer circumference of the base plate in the radial direction. According to the utility model, the design that the air outlet ends of the blades exceed the periphery of the base plate enables airflow to be less hindered when being exhausted, provides a larger air outlet space, improves the condition that the airflow is blocked and extruded on the inner side of the air outlet due to insufficient air outlet space, increases the exhaust air rate, and reduces high-frequency noise generated by airflow friction at the same time; and the use experience of operators is improved.

Description

Technical Field

[0001] This utility model relates to the field of power tool technology, specifically to a centrifugal impeller and a power tool. Background Technology

[0002] Existing power tools often have extremely high motor speeds. For example, diamond drilling machines can reach motor speeds of 25,000 rpm. Therefore, it is necessary to install centrifugal fans in power tools. These fans drive airflow through the motor to dissipate heat.

[0003] However, for handheld power tools, the small size of the tool itself limits the size of the air outlet on the casing and the space between the air outlet and the centrifugal impeller, resulting in insufficient air outlet area. This causes airflow obstruction and poor flow near the air outlet, which not only affects the air volume and heat dissipation but also easily leads to high-frequency whistling sounds, causing hearing discomfort for the operator. Utility Model Content

[0004] The present invention aims to provide a centrifugal fan and power tool that can improve the situation of uneven airflow at the outlet of the centrifugal fan, enhance heat dissipation, and reduce high-frequency whistling noise.

[0005] To solve the above-mentioned technical problems, this utility model provides a fan assembly, comprising:

[0006] A chassis for connection and fixation to a drive shaft, the chassis having a first side and a second side disposed opposite each other in a thickness direction, the thickness direction being parallel to the axial direction; and...

[0007] Multiple blades are disposed on the first side, and the multiple blades are distributed circumferentially. Each blade extends from the inner periphery to the outer periphery of the chassis and has an air inlet end relatively close to the center of the chassis and an air outlet end relatively far from the center of the chassis. Among the multiple blades, at least some of the air outlet ends of the blades extend radially beyond the outer periphery of the chassis.

[0008] Optionally, the diameter of the chassis is D1, the outer diameter of the centrifugal impeller is D2, and the ratio of D1 / D2 is greater than or equal to 80% and less than or equal to 95%; and / or,

[0009] In an axial projection view, at least a portion of the air outlet of the blades extends radially beyond the outer periphery of the chassis by a dimension L greater than or equal to 4 mm and less than or equal to 6 mm.

[0010] Optionally, the plurality of blades are integrally formed with the chassis.

[0011] Optionally, the second side protrusion is provided with multiple reinforcing ribs and annular ribs, the multiple annular ribs are arranged at intervals along the inner and outer rings, the multiple reinforcing ribs are arranged at intervals along the circumference and extend radially respectively.

[0012] Optionally, each of the blades is a backward-curved blade.

[0013] To solve the above-mentioned technical problems, this utility model provides an electric tool, comprising:

[0014] A housing, wherein an installation cavity is formed within the housing;

[0015] The output shaft is rotatably mounted on the housing;

[0016] A drive assembly, disposed within the mounting cavity, includes a motor driveably connected to the output shaft; and,

[0017] As described above, the centrifugal impeller is disposed within the mounting cavity, and the motor shaft of the motor forms a drive shaft for driving the centrifugal impeller; alternatively, the motor is connected to the drive shaft of the centrifugal impeller via a transmission mechanism.

[0018] Optionally, the housing has an air outlet that connects the mounting cavity and the outside of the housing. Multiple air outlets are provided, and the multiple air outlets are distributed at intervals along the circumference and are radially corresponding to the outer circumference of the centrifugal impeller.

[0019] Optionally, the radial projection of the air outlet end of the blade is located within the radial projection range of the air outlet.

[0020] Optionally, each of the air outlets extends axially beyond each of the air outlet ends, and the axial dimension of the portion of each air outlet extending beyond the first side is S1, where S1 is greater than or equal to 1.8 mm and less than or equal to 2 mm.

[0021] Optionally, the housing includes a first housing and a second housing that are detachably connected in sequence along the axial direction, the motor is installed in the first housing, and the second housing has a plurality of air outlets;

[0022] Wherein, the second housing and the first housing are at least partially spaced apart to form an air outlet gap, the air outlet gap being radially opposite to the plurality of blades, and the axial dimension of the air outlet gap being S2, S2 being greater than or equal to 1.8 mm and less than or equal to 2 mm; and / or,

[0023] Each of the air outlets extends axially through the end of the first housing into the second housing, thus being open.

[0024] The technical solution provided by this utility model has the following advantages:

[0025] The centrifugal impeller provided by this utility model includes a chassis and multiple blades. The chassis is connected and fixed to a drive shaft, which drives the chassis to rotate, thereby driving the multiple blades to rotate. The chassis has a first side and a second side arranged opposite each other in the axial direction. The multiple blades are arranged on the first side, and the multiple blades are distributed circumferentially. Each blade extends from the inner circumference to the outer circumference of the chassis and has an air inlet end relatively close to the center of the chassis and an air outlet end relatively far from the center of the chassis. At least some of the blades have air outlet ends that extend radially beyond the outer circumference of the chassis. In the embodiment provided by this utility model, the design of the air outlet ends of the blades extending beyond the outer circumference of the chassis reduces airflow obstruction during discharge, provides a larger air outlet space, improves the situation where airflow is blocked and squeezed inside the air outlet due to insufficient air outlet space, increases the exhaust volume while reducing high-frequency noise generated by airflow friction, and improves the user experience for operators. Attached Figure Description

[0026] To more clearly illustrate the specific embodiments of this utility model or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0027] Figure 1 A three-dimensional structural diagram of an embodiment of the power tool provided by this utility model;

[0028] Figure 2 for Figure 1 Exploded view of the three-dimensional structure of a Chinese power tool;

[0029] Figure 3 for Figure 2 A three-dimensional structural diagram of a centrifugal fan.

[0030] Figure 4 for Figure 3 A three-dimensional structural diagram of a centrifugal fan from another perspective;

[0031] Figure 5 for Figure 3 Front view of a centrifugal fan rotor;

[0032] Figure 6 for Figure 2 A partial sectional view of the first casing, the centrifugal impeller, and the second casing;

[0033] Figure 7 for Figure 2 A three-dimensional structural diagram of the second shell in the middle;

[0034] Figure 8 for Figure 7 A three-dimensional structural diagram of the second shell from another perspective.

[0035] Explanation of reference numerals in the attached figures:

[0036] 100-Power tool; 10-Centrifugal impeller; 11-Blade; 111-Air inlet; 112-Air outlet; 12-Chassis; 121-First side; 122-Second side; 1221-Reinforcing rib; 1222-Annular rib; 123-Shaft hole; 20-Housing; 21-First housing; 22-Second housing; 23-Third housing; 24-Air outlet gap; 25-Air outlet; 26-Bearing seat; 30-Motor shaft; 40-Output shaft. Detailed Implementation

[0037] The technical solution of this utility model will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this utility model. The present utility model will be described in detail below with reference to the accompanying drawings and embodiments. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of this utility model can be combined with each other.

[0038] It should be noted that the terms "first," "second," etc., in the specification, claims, and drawings of this utility model are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence.

[0039] Please see Figures 1 to 8 This utility model provides a centrifugal impeller 10 and an electric tool 100 including the impeller. In this embodiment, the electric tool 100 is mainly a small electric tool, preferably a handheld electric tool, such as an angle grinder, a grooving machine, an electric drill, etc.

[0040] Please see Figure 1 and Figure 2 The power tool 100 includes a housing 20, an output shaft 40, a drive assembly, and a centrifugal impeller 10. The housing 20 has a mounting cavity, providing mounting space and protection for the various components. Its material can be selected as needed; the material of the housing 20 should be lightweight, have good insulation properties, and strong impact resistance, preferably made of high-strength engineering plastics.

[0041] The drive assembly, including a motor (preferably a high-speed motor with high heat dissipation requirements), is housed within the mounting cavity. The motor drives an output shaft 40, which is rotatably mounted on the housing 20 to perform operations on the target workpiece under the motor's drive. The structure and operation of the output shaft 40 depend on the type of power tool 100. Taking an electric screwdriver as an example, the output shaft transmits the torque output by the motor, driving the screwdriver head to rotate and tighten or loosen screws. The motor and output shaft 40 can be coaxially mounted or connected via a transmission mechanism instead of being coaxially mounted.

[0042] The housing 20 is also provided with an air inlet and an air outlet 25. The centrifugal impeller 10 is disposed in the mounting cavity. When it rotates, it drives the airflow to flow into the mounting cavity from the air inlet and out of the air outlet 25. The airflow flowing through the motor carries away the heat of the motor, thereby achieving heat dissipation for the motor. Optionally, the centrifugal impeller 10 can be directly driven to rotate by the aforementioned motor, that is, the motor shaft 30 constitutes the drive shaft of the centrifugal impeller 10. Alternatively, the motor can be connected to the drive shaft of the centrifugal impeller 10 through a transmission mechanism to drive the centrifugal impeller 10 to rotate. In this embodiment, it is preferable to use the method of directly driving the centrifugal impeller 10 to rotate to achieve high-speed rotation of the centrifugal impeller 10. This method is simple and reliable in structure, and allows for synchronous start-up with the motor, achieving efficient real-time heat dissipation for the motor.

[0043] In this embodiment, the centrifugal impeller 10 and the motor shaft 30 are coaxially connected. This coaxial connection can take several forms. Specifically, the centrifugal impeller 10 and the motor shaft 30 can be integrally formed. Alternatively, the centrifugal impeller 10 can have a centrally located shaft hole 123, and the motor shaft 30 can be welded to the shaft hole 123 for coaxial connection and fixation. Another option is that the centrifugal impeller 10 and the motor shaft 30 can be circumferentially fixedly connected via a key or other means.

[0044] The centrifugal impeller 10 provided in this embodiment, through a special structural design, can increase the air outlet space, thereby improving the unsmooth airflow at the air outlet end 112 of the centrifugal impeller 10, enhancing the heat dissipation effect, and reducing high-frequency whistling noise.

[0045] For details, please continue reading Figures 3 to 5In this embodiment, the centrifugal impeller 10 includes a chassis 12 and multiple blades 11. The chassis 12 is connected and fixed to a drive shaft, which drives the chassis 12 to rotate, thereby driving the multiple blades 11 to rotate. The chassis 12 has a first side 121 and a second side 122 arranged opposite each other in the thickness direction, and the thickness direction of the chassis 12 is parallel to the axial direction. The multiple blades 11 are arranged on the first side 121, and the multiple blades 11 are distributed circumferentially. Each blade 11 extends from the inner circumference to the outer circumference of the chassis 12 and has an air inlet end 111 relatively close to the center of the chassis 12 and an air outlet end 112 relatively far from the center of the chassis 12. In this embodiment, the chassis 12 provides stable support for the blades 11, ensuring that the blades 11 will not be affected by rotational deformation when the centrifugal impeller 10 rotates at high speed. At the same time, the chassis 12 also serves to block the airflow along the axial direction, so that the airflow to the centrifugal impeller 10 enters along the axial direction and exits radially to the outer circumference.

[0046] When the centrifugal impeller 10 is working, air enters from the inlet end 111, flows radially outward under the push of the blades 11, and is finally discharged from the outlet end 112. Since the motor runs at high speed, the centrifugal impeller 10 also rotates at high speed, so heat dissipation efficiency is crucial.

[0047] In this embodiment, at least some of the blades 11 have their outlet ends 112 extending radially beyond the outer periphery of the chassis 12. Preferably, all blades 11 have their outlet ends 112 extending radially beyond the outer periphery of the chassis 12. It should be noted that in this embodiment, the dimensions of each blade 11 extending beyond the outer periphery of the chassis 12 can be different or the same. To facilitate the manufacturing of the centrifugal impeller 10 and ensure uniform airflow, it is preferable that each blade 11 has the same shape and size, and that the dimensions of each blade 11 extending beyond the outer periphery of the chassis 12 are consistent. This design effectively increases the air exhaust space, preventing situations where the space at the outlet ends 112 of each blade 11 is too small, leading to increased local airflow compression and turbulence, thus hindering smooth airflow.

[0048] Specifically, the design of the air outlet 112 of the blade 11 extending beyond the outer periphery of the chassis 12 reduces airflow obstruction during exhaust, thereby increasing exhaust volume and enhancing heat dissipation. Simultaneously, it provides a larger exhaust space, mitigating the airflow congestion and compression inside the outlet 25 caused by insufficient space, reducing high-frequency noise generated by airflow friction, and improving the operator's experience. Furthermore, this design increases exhaust space and improves exhaust efficiency within the space-constrained power tool 100, while maintaining the overall size of the centrifugal impeller 10.

[0049] Building upon the previous embodiment, the size design of the chassis 12 has a significant impact on the performance of the centrifugal impeller 10. Specifically, if the chassis 12 is too small, the root strength of the blades 11 will be insufficient, making them prone to breakage. If the chassis 12 is too large, it will reduce the effective working area of ​​the blades 11, thus lowering heat dissipation efficiency. In this embodiment, as... Figure 5 As shown, the diameter of the chassis 12 is D1, and the outer diameter of the centrifugal impeller 10 is D2. The ratio of D1 / D2 is greater than or equal to 80% and less than or equal to 95%. This proportional design ensures that the chassis 12 can provide sufficient support strength for the blades 11, preventing the blades 11 from deforming during high-speed rotation and affecting the overall performance of the impeller. It also ensures that the blades 11 have sufficient effective working area, thereby generating sufficient air volume and air pressure to meet the heat dissipation requirements of the motor.

[0050] Similarly, the radial extension of the air outlet 112 of the blade 11 beyond the outer periphery of the chassis 12 also significantly affects the performance of the centrifugal impeller 10. It is understandable that when the extension of the blade 11 beyond the outer periphery of the chassis 12 is too small, the increase in airflow is not significant, and the heat dissipation efficiency cannot be effectively improved. Conversely, when the extension of the blade 11 beyond the outer periphery of the chassis 12 is too large, the chassis 12 cannot effectively guide the airflow radially, and turbulence is more likely to occur, reducing the airflow volume. Therefore, in an optional embodiment, such as... Figure 5 As shown, at least a portion of the blades 11 have an outlet end 112 that extends radially beyond the outer periphery of the chassis 12 by a dimension L greater than or equal to 4 mm and less than or equal to 6 mm. This dimensional design ensures that the centrifugal impeller 10 can maintain sufficient outlet space while preventing the blades 11 from extending too far beyond the chassis 12, which could lead to insufficient support from the chassis 12 or axial dissipation of airflow, reducing air volume. In this embodiment, through the optimized design of the above-mentioned dimensional proportions, the heat dissipation efficiency of the centrifugal impeller 10 can be effectively improved, noise can be reduced, and the centrifugal impeller 10 can achieve optimal heat dissipation within a limited space.

[0051] Furthermore, there are various ways to fix the multiple blades 11 to the chassis 12. In this embodiment, the multiple blades 11 and the chassis 12 are integrally formed. Specifically, the centrifugal impeller 10 can be produced by injection molding or die casting. This integral design simplifies the manufacturing process, reduces production costs, and improves the overall strength and reliability of the centrifugal impeller 10. Compared with a split structure, there are no connecting gaps between the integrally formed blades 11 and the chassis 12, avoiding the risk of impeller failure due to loosening or detachment of the connection. In addition, the integral structure can also optimize airflow. Since there are no connecting gaps, the airflow is smoother when flowing between the blades 11 and the chassis 12, reducing turbulence and energy loss, thereby improving the heat dissipation efficiency of the impeller.

[0052] Based on the above embodiments, please refer to Figure 4 Preferably, the second side 122 of the chassis 12 is provided with a reinforcing structure. Specifically, the second side 122 is provided with multiple reinforcing ribs 1221 and annular ribs 1222. The multiple annular ribs 1222 are arranged at intervals along the inner and outer rings, and the multiple reinforcing ribs 1221 are arranged at intervals along the circumference and extend radially respectively. This design of adding reinforcing ribs 1221 and annular ribs 1222 to the second side 122 of the chassis 12 can significantly improve the structural strength and rigidity of the chassis 12 and prevent it from deforming or breaking during high-speed rotation.

[0053] Based on the above embodiments, each blade 11 is a backward-curved blade. Specifically, as shown... Figure 3 As shown, backward-curved blades refer to a configuration where the centrifugal impeller 10 rotates in the forward direction (clockwise or counterclockwise) under the drive of the drive shaft, while the blades 11 bend in the opposite direction (clockwise or counterclockwise) from their inlet end 111 towards their outlet end 112. Compared to conventional blades that bend in the same direction, the backward-curved blades bend in the opposite direction to the rotation. This reverse-curving blade effectively reduces the friction frequency between the blades 11 and the air, decreases friction and turbulence between the air and the blades 11, and reduces high-frequency vibrations caused by friction between the blades 11 and the air. This, in turn, reduces the probability of high-frequency whistling sounds and improves the user experience for operators. Simultaneously, smoother airflow also helps improve the heat dissipation efficiency of the fan components.

[0054] The curvature of the blades 11 should be designed according to requirements. Generally, the angle between the line connecting the air inlet end 111 and the air outlet end 112 of each blade 11 and the diameter extension passing through the air inlet end 111 should not exceed 45 degrees. It is understandable that excessive curvature of the blades 11 will significantly reduce airflow, thus adversely affecting the working efficiency of the centrifugal impeller 10. Conversely, insufficient curvature of the blades 11 will result in insignificant reduction of high-frequency vibrations caused by friction between the blades 11 and the air, still producing high-frequency whistling noises during operation. Therefore, the curvature of the blades 11 needs to be designed according to the dimensions of the power tool 100 itself and the specific airflow and pressure requirements of different types of power tools.

[0055] Based on the above embodiments, please refer to the following: Figure 1 , Figure 2 and Figure 6 The air outlet 25 on the housing 20 is positioned opposite to the air outlet ends 112 of the multiple blades 11. Specifically, as shown... Figure 7 and Figure 8As shown, multiple air outlets 25 are provided, which are spaced apart circumferentially and radially corresponding to the outer periphery of the centrifugal impeller 10. Specifically, when the centrifugal impeller 10 rotates, it draws air in through the air inlet, which then flows axially towards the air inlet end 111 of the multiple blades 11. The air is accelerated by the blades 11 and flows radially towards the outer periphery of the centrifugal impeller 10, finally exiting from the air outlet end 112 towards the air outlet 25. The radial correspondence between the multiple air outlets 25 and the outer periphery of the centrifugal impeller 10 allows for smooth airflow discharge from the casing 20, thereby increasing gas flow velocity and improving heat dissipation efficiency. The spaced circumferential distribution of the multiple air outlets 25 ensures more even airflow discharge from the casing 20, preventing localized overheating.

[0056] It is understandable that the size of the air outlet 25 will affect the heat dissipation effect. Preferably, the radial projection of the air outlet end 112 of the blade 11 is within the radial projection range of the air outlet 25. It should be noted that the position of the blade 11 changes when the centrifugal impeller 10 rotates. Therefore, the above-mentioned limitation of the projection range refers to the case where the air outlet end 112 of the blade 11 is directly opposite the air outlet 25 (the center points of the two are on the same radial straight line).

[0057] Thus, when the power tool 100 is working, the centrifugal impeller 10 rotates at high speed, and the airflow discharged from the air outlet 112 of the blades 11 has a certain speed and direction. If the radial projection area of ​​the air outlet 25 is less than or equal to the radial projection area of ​​the air outlet 112 of the blades 11, the airflow will be blocked to some extent by the inner wall of the housing 20 during discharge, resulting in a decrease in airflow speed or even turbulence, thereby affecting the heat dissipation effect. In this embodiment, by making the radial projection of the air outlet 112 of the blades 11 within the radial projection range of the air outlet 25, airflow resistance can be reduced, allowing the airflow to be discharged from the housing 20 more smoothly. This reduces the friction between the blades 11 and the air, lowering the probability of high-frequency whistling noise.

[0058] Preferably, please refer to Figure 6 and Figure 7 The air outlet 25 extends beyond each air outlet end 112 at least once in the axial direction, and extends beyond each air outlet end 112 on at least one side in the circumferential direction. This allows the air outlet 25 to provide a larger air outlet area. As the airflow flows from the air outlet end 112 to the air outlet 25, the flow velocity decreases, and the airflow is subjected to less compression, thereby reducing noise. At the same time, the larger air outlet area 25 also reduces airflow resistance and improves heat dissipation efficiency.

[0059] Specifically, please refer to Figure 6The axial dimension of each air outlet 25 extending beyond the first side 121 is S1, which is greater than or equal to 1.8 mm and less than or equal to 2 mm. If S1 is too small, the airflow will still be blocked by the inner wall of the casing 20 during discharge, affecting the heat dissipation effect. If S1 is too large, the airflow will diffuse excessively before discharge, resulting in a decrease in airflow velocity and a decrease in heat dissipation efficiency. By controlling S1 between 1.8 mm and 2 mm, the flow path of the airflow during discharge can be precisely controlled, allowing the airflow to flow smoothly while maintaining a certain velocity, thereby achieving the best heat dissipation effect. In addition, this dimensional control can also effectively reduce the probability of high-frequency whistling sounds. High-frequency whistling sounds are usually caused by resonance when the airflow passes through narrow gaps. By precisely controlling the gap between the air outlet 25 and the blade 11, resonance of the airflow can be avoided, thereby reducing the generation of high-frequency whistling sounds.

[0060] Based on the above embodiments, please refer to the following: Figure 1 , Figure 2 and Figure 6 and Figure 7 The housing 20 includes a first housing 21 and a second housing 22 that are detachably connected sequentially along the axial direction. The motor is installed in the first housing 21, and the second housing 22 has multiple air outlets 25. Optionally, the housing 20 also includes a third housing 23 for rotatably mounting the output shaft 40. Preferably, the drive shaft is rotatably supported in the second housing 22 by a bearing seat 26 disposed in the second housing 22, and one end extends into the third housing 23 for transmission connection with the output shaft 40, while the other end extends into the first housing 21. Thus, during the production process, the first housing 21, the second housing 22, and the third housing 23 can be processed and pre-treated separately before assembly, improving production efficiency. During use, if components such as the centrifugal impeller 10 or the motor malfunction, the user or maintenance personnel can easily disassemble the corresponding first housing 21, the second housing 22, and / or the third housing 23 for repair or replacement.

[0061] Furthermore, the second housing 22 and the first housing 21 are at least partially spaced apart to form an air outlet gap 24. The air outlet gap 24 is radially opposite to the plurality of blades 11, and the axial dimension of the air outlet gap 24 is S2, which is greater than or equal to 1.8 mm and less than or equal to 2 mm. In this embodiment, the air outlet gap 24 effectively increases the air outlet area by utilizing the assembly gap between the first housing 21 and the second housing 22, preventing the airflow from being blocked or squeezed inside the air outlet 25. This further improves the heat dissipation efficiency while reducing the probability of high-frequency whistling. By controlling S2 between 1.8 mm and 2 mm, the airflow can flow smoothly and maintain a certain speed during discharge, thereby achieving the best heat dissipation effect.

[0062] Optionally, each air outlet 25 extends through the second housing 22 axially toward the end of the first housing 21, thus being open. Preferably, each air outlet 25 connects to the air outlet gap 24 through its open end. This design, on the one hand, further increases the air outlet area, and on the other hand, makes the second housing 22 easier to demold during the molding process, facilitating manufacturing and reducing production costs.

[0063] Obviously, the embodiments described above are only some embodiments of this utility model, and not all embodiments. Based on the embodiments of this utility model, those skilled in the art can make other variations or modifications without creative effort, and all such variations or modifications should fall within the protection scope of this utility model.

Claims

1. A centrifugal fan wheel, characterized in that The centrifugal fan comprises: a base plate for being fixedly connected with a driving shaft, the base plate having a first side and a second side oppositely arranged in a thickness direction, the thickness direction being parallel to the axial direction; and a plurality of blades arranged on the first side, the plurality of blades being spaced apart in a circumferential direction, each of the blades extending from an inner periphery of the base plate to an outer periphery of the base plate, and having an air inlet end close to a center of the base plate and an air outlet end away from the center of the base plate, at least part of the air outlet ends of the blades extending beyond the outer periphery of the base plate in a radial direction. A diameter of the base plate is D1, an outer diameter of the centrifugal fan is D2, D1 / D2 is greater than or equal to 80% and less than or equal to 95%; and / or 2. The centrifugal fan wheel of claim 1, wherein In a projection view along the axial direction, a size L of the air outlet end of at least part of the blades extending beyond the outer periphery of the base plate in the radial direction is greater than or equal to 4 mm and less than or equal to 6 mm. The plurality of blades are integrally formed with the base plate.

3. The centrifugal fan wheel of claim 1, wherein The second side is provided with a plurality of reinforcing ribs and annular ribs, the plurality of annular ribs being arranged in an inner-outer annular space, and the plurality of reinforcing ribs being arranged in the circumferential direction and extending in the radial direction.

4. The centrifugal fan wheel of claim 3, wherein Each of the blades is a backward-curved blade.

5. The centrifugal fan wheel according to any one of claims 1 to 4, characterized in that The centrifugal fan comprises:

6. A power tool characterized by comprising: a housing, an installation cavity being formed in the housing; an output shaft rotatably mounted in the housing; a driving assembly arranged in the installation cavity and comprising a motor in transmission connection with the output shaft; and the centrifugal fan according to any one of claims 1 to 5 is arranged in the installation cavity, a motor shaft of the motor forming a driving shaft for driving the centrifugal fan, or the motor is in transmission connection with the driving shaft of the centrifugal fan through a transmission mechanism. A plurality of air outlets are formed in the housing and in communication with the installation cavity and an outside of the housing, the plurality of air outlets being spaced apart in the circumferential direction and arranged in the radial direction corresponding to an outer periphery of the centrifugal fan.

7. The power tool as described in claim 6, characterized in that, The air outlet end of the blade is projected in the radial direction within a projection range of the air outlet in the radial direction.

8. The power tool of claim 7, wherein the first and second electrical conductors are electrically connected to the motor. Each of the air outlets extends beyond each of the air outlet ends in the axial direction, and a size S1 of a portion of each of the air outlets extending beyond the first side in the axial direction is greater than or equal to 1.8 mm and less than or equal to 2 mm.

9. The power tool of claim 8, wherein, The housing comprises a first housing and a second housing which are detachably connected in sequence in the axial direction, the motor is mounted in the first housing, and the second housing is provided with the plurality of air outlets; 10. The power tool of claim 7, wherein the first and second electrical conductors are electrically connected to the motor. wherein the second housing and the first housing are at least partially spaced apart to form an air outlet gap, the air outlet gap is arranged opposite to the plurality of blades in the radial direction, a size S2 of the air outlet gap in the axial direction is greater than or equal to 1.8 mm and less than or equal to 2 mm; and / or each of the air outlets penetrates through the second housing towards an end side of the first housing in the axial direction to be arranged in an open manner. ​

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