Switched reluctance motor with heat dissipation structure and electric garden tools containing such motor

Abstract

A switched reluctance motor with a heat dissipation structure and an electric garden tool including the motor are disclosed. The switched reluctance motor includes: a housing having opposing first and second ends and a tubular wall extending between the first and second ends; an air inlet component disposed near the first end and having an air inlet; an air outlet component disposed near the second end and having an air outlet; a switched reluctance motor body disposed in the housing and having an output shaft extending in a first direction, a rotor and a stator disposed around the output shaft; a controller component disposed in the housing and located in the first direction between the air inlet component and the switched reluctance motor body; and an exhaust component disposed on the output shaft and located on the side of the switched reluctance motor body opposite to the controller component; wherein at least one air duct is formed between the housing and the controller component and the switched reluctance motor body to dissipate heat from the controller component and the switched reluctance motor body.

Description

Technical Field

[0001] This invention relates to a switched reluctance motor with a heat dissipation structure and an electric garden tool incorporating the switched reluctance motor. Background Technology

[0002] Electric motors are widely used in homes, gardens, and environmental maintenance. Currently, most power tool and garden tool manufacturers use series-wound motors to drive the rotation of mechanical structures. As is well known, series-wound motors use carbon brushes and commutators, resulting in short lifespans, high failure rates, and carbon brush dust that pollutes the environment. Some manufacturers use permanent magnet brushless DC motors to drive the rotation of mechanical structures, but permanent magnet brushless DC motors require permanent magnet materials, making them expensive, prone to demagnetization under overload conditions, and easily attracting ferrous dust, leading to motor failure.

[0003] The use of switched reluctance motors effectively overcomes the above problems, but using switched reluctance motors also brings some other issues.

[0004] First, in switched reluctance motors, the power rectifier module and the motor drive module are designed on an integrated board controller assembly. The excessive size makes it difficult for external airflow to circulate, which affects heat dissipation and also affects the overall convenience of the machine. In addition, the controller assembly and the motor body need to be cooled separately, which increases the corresponding cost.

[0005] Secondly, when using an integrated centralized heat dissipation solution, the controller component is placed off the optimal heat dissipation path of the reluctance motor, making it difficult for the controller component to dissipate heat. Furthermore, when using components with insufficient temperature resistance, the controller component is prone to burnout, ultimately leading to motor failure. Using components with higher temperature resistance is too costly.

[0006] Furthermore, the unreasonable design of the air inlet and outlet dimensions of the cooling duct in the switched reluctance motor leads to the inability to achieve the best heat dissipation effect.

[0007] Furthermore, switched reluctance motors generate significant heat due to their high power density. Therefore, cooling fans, such as centrifugal or axial fans, are needed to increase heat dissipation. However, these fans consume some of the motor's own power, leading to a decrease in output power and a reduction in power density. A mismatch between fan size and motor power also causes problems. Oversized fan blades occupy too much space, especially in the axial height, affecting the usability of the machine (e.g., garden tools and power tools) and excessively consuming the motor's own power. Conversely, undersized fan blades result in ineffective heat dissipation. Summary of the Invention

[0008] Therefore, the purpose of this invention is to provide a switched reluctance motor with a heat dissipation structure and an electric garden tool containing the switched reluctance motor, which can integrate and centrally dissipate heat from the motor and controller components, thus resulting in small size, high heat dissipation efficiency, low cost and long life.

[0009] This invention relates to a switched reluctance motor with a heat dissipation structure, the switched reluctance motor comprising: a housing having opposing first and second ends and a tubular wall extending between the first and second ends; an air inlet component disposed near the first end and having an air inlet; an air outlet component disposed near the second end and having an air outlet; a switched reluctance motor body disposed within the housing and having an output shaft extending in a first direction, a rotor and a stator disposed around the output shaft; a controller component disposed within the housing and located in the first direction between the air inlet component and the switched reluctance motor body; and an exhaust component disposed on the output shaft and located on the side of the switched reluctance motor body opposite to the controller component; wherein at least one air duct is formed between the housing and the controller component and the switched reluctance motor body to dissipate heat from the controller component and the switched reluctance motor body.

[0010] In one embodiment, the controller component includes: a bracket fixed in a housing; and a motor drive board and a power rectifier board arranged side-by-side on the bracket in a second direction perpendicular to the first direction.

[0011] In one embodiment, the at least one air duct includes a first air duct formed between the housing and the controller component and the stator, and a second air duct formed between the stator and the rotor.

[0012] In one embodiment, the switched reluctance motor body further includes a first end cover and a second end cover located at both ends of the rotor and the stator, the first end cover and the second end cover having a hollowed-out form.

[0013] In one embodiment, the bracket of the controller component is disposed on the first end cap, and the bracket is a rectangular frame and the plane in which it lies is parallel to the first direction.

[0014] In one embodiment, the switched reluctance motor further includes a mounting plate, with a second end of the housing disposed on the mounting plate and the output shaft of the switched reluctance motor body passing through a hole in the mounting plate.

[0015] In one embodiment, the air outlet component is integrated with the mounting plate as a single component.

[0016] In one embodiment, the air outlet component is disposed on the tubular wall of the housing.

[0017] In one embodiment, the housing has a plurality of protrusions that project inward from its tubular wall and extend along a portion of the tubular wall for securing the switched reluctance motor body within the housing.

[0018] In one embodiment, a plurality of protrusions are evenly distributed circumferentially on the tubular wall.

[0019] In one embodiment, the tubular wall forms a non-zero angle with the first direction.

[0020] In one embodiment, the angle is in the range of 2° to 5°.

[0021] In one embodiment, the angle is in the range of 3° to 4.5°.

[0022] In one embodiment, the housing includes a cavity at the second end for receiving the exhaust component.

[0023] In one embodiment, the exhaust component includes multiple fan blades.

[0024] In one embodiment, the height of the fan blade in the first direction is in the range of 4.5 mm to 7 mm.

[0025] In one embodiment, the distance between the air intake component and the controller component along the first direction is in the range of 5 mm to 20 mm.

[0026] In one embodiment, the distance is in the range of 8 mm to 12 mm.

[0027] In one embodiment, the ratio of the air inlet area to the air outlet area of ​​the housing is between 1:3 and 1:1.5.

[0028] In one embodiment, the ratio of the air inlet area to the air outlet area of ​​the housing is between 1:2.5 and 1:2.

[0029] The present invention also relates to an electric garden tool, which includes a switched reluctance motor as described above. Attached Figure Description

[0030] The advantages and objects of the invention will be better understood from the preferred embodiments described in detail below with reference to the accompanying drawings. The drawings are not to scale in order to better illustrate the relationships between the components. In the drawings:

[0031] Figure 1 A three-dimensional external view of the switched reluctance motor with a heat dissipation structure of the present invention is shown.

[0032] Figure 2 for Figure 1 A partial cross-sectional view of a switched reluctance motor;

[0033] Figure 3 A schematic diagram of the housing of the switched reluctance motor with a heat dissipation structure according to the present invention is shown;

[0034] Figure 4a and Figure 4b An exploded view of the structure of the switched reluctance motor with heat dissipation structure of the present invention is shown in different directions.

[0035] Figure 5 A schematic diagram of a switched reluctance motor body according to an embodiment of the present invention is shown;

[0036] Figure 6 Show Figure 5 A schematic diagram of the first and second end covers of the switched reluctance motor body;

[0037] Figure 7 Show Figure 5 A schematic diagram of the cross-sections of the stator and rotor of a switched reluctance motor.

[0038] Figure 8 A schematic diagram of a controller component according to an embodiment of the present invention is shown;

[0039] Figure 9 A schematic diagram showing the airflow path in the switched reluctance motor with heat dissipation structure of the present invention is shown.

[0040] Figure 10 A schematic diagram illustrating the dimensions of various components in one embodiment of the present invention;

[0041] Figure 11 To show Figure 10 A schematic diagram showing the dimensions of the fan blades in the exhaust component;

[0042] Figure 12 A schematic diagram of the housing of a switched reluctance motor according to another embodiment of the present invention is shown; and

[0043] Figure 13a and Figure 13b An exploded view of the structure of an electric garden tool according to an embodiment of the present invention is shown in different directions. Detailed Implementation

[0044] Various embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that, in the drawings, the same reference numerals are assigned to components having substantially the same or similar structure and function, and repeated descriptions of them are omitted. Unless otherwise specified, the terms "first direction," "second direction," "rotation direction," etc., used herein are described with respect to the accompanying drawings of the present invention. The description of "first" and its variations is merely for distinguishing components and does not limit the scope of the invention; "first component" may be written as "second component," etc., without departing from the scope of the invention.

[0045] The accompanying drawings in this specification are schematic diagrams used to help illustrate the concept of the invention, and schematically show the shape of each part and their interrelationship.

[0046] Below, refer to Figures 1 to 11 The preferred embodiments of the present invention will be described in detail below.

[0047] See Figures 1 to 4a According to 4b, a switched reluctance motor 100 with a heat dissipation structure according to an embodiment of the present invention includes a housing 1, an air inlet component 2, an air outlet component 3, a switched reluctance motor body 4, a controller component 5, and an exhaust component 6.

[0048] The outer casing 1 has a tubular wall 11 preferably at an angle to the first direction and opposing first end 12 and second end 13. Figure 1 In the diagram on the left, the first direction is the vertically upward direction. Figure 2 China and Figure 3 In the diagram on the right, the first direction is vertically downward. That is to say, the outer shell gradually expands along the first direction, forming a trumpet shape. For example... Figure 3 As shown, the angle α between the tubular wall of the outer shell and the first direction is in the range of 2° to 5°, preferably in the range of 3° to 4.5°. The cross-sectional shape of the tubular wall is preferably circular, but it can also be other shapes, such as rectangular, polygonal, etc. For example, the outer shell can also be frustum-shaped.

[0049] The air inlet component 2 is located near the first end and has an air inlet 21. For example... Figure 1 , Figure 3 As shown, the air inlet 21 consists of multiple arc-shaped air vents centered on the center of the air inlet component 2. The air inlet not only allows airflow into the housing but also filters impurities to protect the switched reluctance motor. The air inlet 21 can also be a regularly arranged rectangular air vent. As shown, the air inlet component 2 is integrally formed with the housing as a single component; that is, the air inlet is located on the end wall at the first end of the housing. However, in other embodiments of the present invention, the air inlet component can also be a component separate from the housing, which can be connected to the first end of the housing by screws or clips.

[0050] The air outlet component 3 is positioned near the second end of the housing and has an air outlet 31. For example... Figure 2 , Figure 3 As shown, the air outlet component 3 is integrally formed with the outer casing as a single component. That is, the air outlet 31 is located on the tubular wall of the outer casing at the second end. When the air outlet component is located on the tubular wall, a centrifugal fan side-discharge method is used. The uniform distribution of the air outlets minimizes resistance to airflow.

[0051] The switched reluctance motor body 4, used to provide power to the mechanical structure, is housed within a casing and has an output shaft 41 extending along a first direction. For example... Figure 5 and Figure 7 As shown, the switched reluctance motor body 4 also includes a rotor 42 and a stator 43 arranged around the output shaft 41. Figure 3 As shown, the housing has a plurality of protrusions 14 (e.g., ribs) projecting inward from its tubular wall and extending along a portion of the tubular wall for securing the switched reluctance motor body within the housing. The plurality of protrusions 14 are evenly distributed circumferentially on the tubular wall. In other embodiments of the invention, depending on the shape of the switched reluctance motor body and installation requirements, the plurality of protrusions 14 may also be unevenly distributed circumferentially on the tubular wall. The number of protrusions 14 is, for example, 3-6.

[0052] The controller component provides control signals to the switched reluctance motor, enabling the motor to operate normally under rated operating conditions. The controller component 5 is housed within the housing and positioned in the first direction between the air inlet component 2 and the switched reluctance motor body 4. For example, the controller component can be fixed to the inside of the tubular wall of the housing.

[0053] The exhaust component enhances heat dissipation and accelerates airflow within the cooling duct. The exhaust component 6 is mounted on the output shaft and located on the side of the switched reluctance motor body 4 opposite to the controller component 5. For example, the housing also includes a cavity 15 at the second end for receiving the exhaust component, such as... Figure 3 As shown. For example, as Figure 4a and 4b As shown, the exhaust component includes a fan blade 16. The fan blade is mounted on the output shaft, for example, via a bushing 17. Figure 11 As shown in the left-hand diagram. Furthermore, to achieve noise reduction, the number of fan blades can be odd. When the fan blades rotate at high speed, a negative pressure zone is formed in the cavity containing them, causing airflow to be rapidly drawn into the cavity and finally flow out from the outlet.

[0054] In addition, such as Figure 2 and Figure 4a , 4b As shown, the switched reluctance motor also includes a mounting plate 7, with the second end of the housing 1 disposed on the mounting plate and the output shaft 41 of the switched reluctance motor body 4 passing through a hole in the mounting plate. The switched reluctance motor can be mounted on a power tool, such as an electric garden tool, via the mounting plate to drive the mechanical structure of the power tool.

[0055] In one embodiment of the present invention, the air outlet component 3 and the mounting plate 7 are integrally formed as a single component, that is, the air outlet is set on the mounting plate 7. At this time, for example, the vertical air outlet method of the axial flow fan is adopted, and the air outlet direction is consistent with the air inlet direction.

[0056] When the air outlet component is mounted on a tubular wall, the air outlet is positioned at the same height as the fan blades. When the air outlet component is mounted on a mounting plate, the air outlet can be configured to be concentric with the fan blades.

[0057] like Figure 2 As shown, the centerline of the controller component (as indicated by the dashed line in the figure) basically coincides with the centerline of the switched reluctance motor body (i.e., the centerline of the output shaft). Figure 2 As shown, at least one air duct is formed between the housing and the controller component and the switched reluctance motor body to dissipate heat from the controller component and the switched reluctance motor body. When the exhaust component 6 is running, the airflow enters the housing through the air inlet, first flows through the controller component 5 and quickly carries away the heat generated by the controller component, then flows through the switched reluctance motor body and carries away the heat generated by the motor, and finally flows out from the outlet.

[0058] The controller components are located closer to the air inlet, allowing them to come into immediate contact with the airflow. This proximity to the air inlet enables the controller components to receive priority heat dissipation and allows for a more compact and smaller design.

[0059] See Figure 4a , Figure 4b and Figure 8 The controller component 5 includes a bracket 51, a motor drive board 52, and a power rectifier board 53. The bracket 51 is fixed within the housing and is, for example, a generally rectangular frame. The plane of the rectangular frame is approximately parallel to the output shaft, thus minimizing resistance to airflow through the controller component. The motor drive board 52 and the power rectifier board 53 are arranged side-by-side on the bracket in a second direction perpendicular to the first direction (the direction of the output shaft 41). In one embodiment of the invention, the bracket may be fixed to the inside of the tubular wall of the housing.

[0060] like Figure 8 As shown in the diagram on the right, in the second direction to the right, a power rectifier board 53 and a motor drive board 52 are respectively installed on both sides of the bracket. Figure 8 The first direction in the diagram is vertically downwards; the second direction in the left-hand diagram is vertically pointing out of the paper; and the second direction in the right-hand diagram is horizontally to the right. The power rectifier board 53 and the motor drive board 52 are electrically connected. For example, the DC power output terminal of the power rectifier board 53 on the left side of the diagram is connected to the DC terminal of the motor drive board 52 on the right side via a metal terminal block passing through a through hole in the bracket.

[0061] The dual-sided design reduces the overall controller component's size to half its original size, minimizing its volume and effectively reducing resistance to airflow within the housing. This smaller size not only lowers manufacturing costs but also reduces airflow resistance within the housing, increasing the cross-sectional area for airflow and improving air pressure and velocity, thus enhancing heat dissipation and reliability. Furthermore, the smaller size facilitates integrated cooling for both the controller and the switched reluctance motor, eliminating the need for separate cooling for each component. This integrated cooling approach improves heat dissipation while reducing costs. Finally, the smaller size enhances the overall ease of use.

[0062] like Figure 5 As shown, the switched reluctance motor body 4 also includes a first end cover 44 and a second end cover 45 located at both ends of the rotor 42 and stator 43. The first end cover 44 is located on the side of the switched reluctance motor body 4 facing the controller component, and the second end cover 45 is located on the side of the switched reluctance motor body 4 facing the exhaust component. In particular, as Figure 6 As shown, the first end cap 44 and the second end cap 45 have a hollowed-out design. In this way, airflow can flow into the switched reluctance motor body 4 almost unobstructed.

[0063] See you again Figure 4a and 4b The bracket 51 of the controller component 5 is mounted on the first end cover 44. This makes the wiring connection between the controller component and the motor more convenient and simple.

[0064] See you again Figure 7 In the switched reluctance motor body, the stator 43 is located outside the rotor 42, both surrounding the output shaft 41 and forming a stator-rotor gap with each other. Based on the principle of minimum reluctance, the switched reluctance motor generates corresponding reluctance torques due to the different reluctances of the stator and rotor at different relative positions. The rotor has an alternating structure of rotor salient poles and rotor recesses, and the stator has an alternating structure of stator salient poles and stator recesses. For example, the stator has six stator recesses, and the rotor has four rotor salient poles. The rotor recesses and stator recesses form a large stator-rotor gap. Therefore, a first air duct is formed between the housing 1 and the controller component 5, and between the stator 43 of the switched reluctance motor body 4, and a second air duct is formed in the gap between the stator 43 and the rotor 42.

[0065] like Figure 9As shown, after air flows through the controller components, a portion of the air flows into the first air duct, while the other portion flows almost unobstructed through the perforated first end cover into the second air duct. Subsequently, it merges with the portion of air flowing through the first air duct through the perforated second end cover, and finally flows out from the outlet. By increasing the air duct through the gap between the stator and rotor, heat can be dissipated simultaneously from both the inner and outer sides of the stator. This increases the heat dissipation area of ​​the switched reluctance motor body, improves the airflow through the entire motor, and better dissipates the heat from the switched reluctance motor body, thereby achieving an enhanced heat dissipation effect.

[0066] See you again Figure 2 and Figure 3 The tubular wall of the outer casing also has a power cord outlet 18, located at the second end of the casing, near the mounting plate. For example... Figure 10 As shown, the power cord 8 of the controller component extends in the space between the switched reluctance motor body and the housing, and together with the power cord 8 of the switched reluctance motor, it is connected to an external power source through a power cord outlet.

[0067] The following is for reference. Figure 7 and Figure 10 The various design parameters of the switched reluctance motor in the embodiments of the present invention are described in detail with examples.

[0068] like Figure 7 As shown, the switched reluctance motor body 4 has an outer diameter D, and the stator outer diameter D is between 60mm and 90mm. The relationship between the rotor outer diameter d and the stator outer diameter D satisfies d:D = 0.42~0.52, preferably d:D = 0.45~0.48. The stator pole arc coefficient α... 定子 = 0.39~0.48, preferably α 定子 =0.40~0.44; Rotor polar arc coefficient β 转子 =0.30~0.40, preferably β 转子 =0.33~0.36. An excessively large pole arc coefficient leads to a decrease in the high-speed output power of the motor and insufficient motor torque; an excessively small pole arc coefficient leads to insufficient starting torque of the motor, reduces the motor's load-carrying capacity, and also results in low motor efficiency and deteriorated motor heat dissipation.

[0069] like Figure 10As shown, the diameter of the opening at the upper first end of the horn-shaped housing 1 is d0, and the diameter of the opening at the lower second end is d3. The opening at the second end is larger than the opening at the first end. Therefore, the angle between the tubular wall of the housing and the first direction is α = 2~5°. Considering the actual manufacturing difficulty and airflow, α is preferably 3.0~3.5°. The relationship between the diameter d3 of the opening at the second end of the housing 1 and the outer diameter D of the switched reluctance motor body is d3 = 1.1~1.4D. If d3 is too small, it affects the heat dissipation contact area of ​​the airflow; if d3 is too large, it is not conducive to rapid airflow.

[0070] For example, the distribution range of the air inlets on the end wall at the first end of the housing is 0.75D to 1.2D.

[0071] The inlet diameter of the cavity used to house the fan blades is d2, where d2 < d3. Preferably, d3 is 5 to 15 mm larger than d2, meaning their relationship satisfies the following formula: d3 = d2 + 5~15 mm. The inner diameter of the cavity used to house the fan blades is d5, which is smaller than d3, to allow for the formation of a negative pressure zone due to the high-speed operation of the fan blades.

[0072] like Figure 10-11 As shown, the inlet cross-sectional diameter of the fan blade is d4, where d2 < d4. Preferably, d4 is 1 to 5 mm larger than d2, meaning they satisfy the following formula: d4 = d2 + 1 to 5 mm. Too large or too small a d4 will affect the rapid flow of air. The outlet cross-sectional diameter of the fan blade is d1, where d4 = 0.33d1 to 0.75d1. For example, d1 = 50 to 85 mm. An excessively large outlet cross-section consumes more motor power, while an excessively small outlet cross-section results in poor motor heat dissipation.

[0073] The outer casing in the first direction ( Figure 10 A space of b = 5 to 20 mm is reserved at the first end in the vertically downward direction to collect airflow. That is, the distance between the air intake component (e.g., air inlet) and the controller component in the first direction is in the range of 5 mm to 20 mm. b is preferably 8 to 12 mm. If b is too small, the amount of airflow will be insufficient; if b is too large, the airflow speed will decrease.

[0074] The preferred relationship between the air inlet area and the air outlet area of ​​the casing is: S 进 ∶S 出 = 1:3 to 1:1.5. More preferably, the ratio of air inlet area to air outlet area is 1:2.5 to 1:2.

[0075] In embodiments of the present invention, the input power P1 of the switched reluctance motor body is above 2500W, and the motor speed is above 15000rpm. When the power consumption P2 of the fan blades of the heat dissipation structure is 0.025~0.06P1, the switched reluctance motor can achieve a good heat dissipation effect while ensuring 70% motor efficiency.

[0076] When the outlet cross-sectional diameter d1 of the fan blade is between 50mm and 85mm, the fan blade height h can be designed to be 4.5 to 7.0mm. Therefore, the fan blade height in the embodiments of the present invention is relatively small, but it still has a high operating speed, for example, above 15000rpm.

[0077] Table 1 below lists various parameters of the fan blades of the heat dissipation structure of the present invention and the fan blades of existing heat dissipation structures.

[0078] Table 1

[0079]

[0080] With the same fan blade outer diameter and motor input power in the heat dissipation structure, the height of the fan blade of the present invention is only 60% of that of the conventionally used fan blade, and the fan blade of the present invention consumes less input power. The reduced fan blade height allows for more space to install the switched reluctance motor, which is beneficial to the overall convenience of the machine. In addition, since the heat dissipation structure of the present invention can achieve enhanced heat dissipation, the actual temperature rise and output power of the switched reluctance motor of the present invention are better than those of existing switched reluctance motors.

[0081] In embodiments of the present invention, the heat dissipation power of the controller component can reach over 60W. Under typical heat dissipation structures, the surface temperature of active devices can reach over 120°C. With the heat dissipation structure of the present invention, external cold air enters the motor housing through the air inlet and first flows through the controller component for preferential heat dissipation, keeping the temperature of the controller component below 100°C. This significantly improves the temperature reliability of the controller component and maintains the overall efficiency of the motor at a high level. After passing through the controller component, the airflow then passes through a first air duct on the outside of the stator and a second air duct in the gap between the stator and rotor, thereby rapidly conducting away the heat dissipated by the controller component and the switched reluctance motor body. This enhanced heat dissipation effect ensures the overall safety and reliability of the motor.

[0082] like Figure 12 As shown, in another embodiment of the switched reluctance motor, the housing 1′ can be frustum-shaped, for example, having an irregular octagonal cross-section; therefore, the housing is called an octagonal frustum. In other examples, the housing can also be a frustum with a cross-section of other polygonal shapes.

[0083] The air intake component is integrally formed with the frustum-shaped housing, that is, the air inlet 21' is formed on the end wall of the housing. The air inlet 21' has, for example, a rectangular shape and is regularly distributed on the end wall of the housing 1'.

[0084] The air outlet component 3′ is formed on the side wall 11′ of the frustum-shaped housing, such as Figure 12 As shown, the air outlet 31′ is located on the side wall 11′ and near the second end.

[0085] like Figure 13a and 13b As shown, an embodiment of the electric garden tool 200' of the present invention includes a housing 201', a main body 202' that operates under the drive of a motor, and a switched reluctance motor 100'. The switched reluctance motor 100' can be fixed at a specific position on the housing 201' of the electric garden tool 200', in which case the housing acts as a mounting plate for the motor. The electric garden tool 200' is, for example, a chainsaw, mainly used for logging and timber processing. The main body 202' is, for example, a chain plate and a chain.

[0086] The second end of the frustum-shaped housing 1′ is disposed on the housing 201′ of the electric garden tool, and the output shaft 41′ of the switched reluctance motor body 4′ passes through a hole in the housing. The output shaft 41′ is connected to the main body 202′ of the electric garden tool via a gear 46′ to drive the main body.

[0087] The frustum-shaped housing 1′ and the housing 201′ of the electric garden tool surround the switched reluctance motor body 4′, controller component 5′, exhaust component, etc., to form at least one heat dissipation duct.

[0088] The controller component 5' is mounted on the first end cap of the switched reluctance motor body 4' via its bracket, located between the air inlet on the housing and the switched reluctance motor body 4'. The power cable 8' of the controller component extends along the motor body within the space between the switched reluctance motor body and the housing, eventually connecting to an external power source via a power cable outlet, together with the power cable of the switched reluctance motor. The centerline of the controller component 5' is substantially coincident with the centerline of the switched reluctance motor body 4'. Furthermore, the motor drive board and power rectifier board of the controller component 5' are arranged side-by-side on the bracket. This reduces the size of the controller component to half its original dimensions and decreases resistance to airflow. Additionally, the proximity of the controller component to the switched reluctance motor facilitates simpler wiring connections between the controller and the motor, improving the convenience of electric garden tools.

[0089] When the exhaust component is operating, the airflow first flows through the controller component, dissipating heat from it. Then, it flows through a first air duct formed between the housing and the stator of the switched reluctance motor body, and a second air duct in the gap between the stator and rotor. Subsequently, under the influence of the negative pressure zone created in the cavity accommodating the rapidly rotating fan blades, the airflow quickly enters the cavity and finally exits through the outlet. Therefore, the switched reluctance motor of this invention has a larger heat dissipation area, a larger airflow, more heat exchange airflow, and faster heat dissipation. Furthermore, this heat dissipation structure prioritizes heat dissipation from the controller component, keeping its surface temperature below 100°C, thus effectively ensuring the reliability of the controller component.

[0090] Figure 13a and 13b The electric garden tool in the example shown has an input power P1 of over 2500W and a centrifugal fan speed of over 15000rpm, but its power consumption P2 is relatively low (P2 = 0.025~0.06P1), resulting in better heat dissipation. Furthermore, the smaller fan size allows for more space to install the switched reluctance motor, improving the convenience of the electric garden tool and reducing its actual temperature rise. Moreover, the airflow from the motor's outlet flows directly to other parts of the electric garden tool, further cooling it and also effectively removing debris and dust.

[0091] Furthermore, the technical features disclosed above are not limited to the combinations of the disclosed features with other features. Those skilled in the art can also make other combinations of the technical features according to the purpose of the invention to achieve the purpose of the invention.

Claims

1. A switched reluctance motor with a heat dissipation structure, characterized in that, The switched reluctance motor includes: The outer shell, which gradually widens along a first direction, has opposing first and second ends and a tubular wall extending between the first and second ends, wherein the tubular wall forms a non-zero angle with the first direction. An air intake component is located near the first end and has an air inlet. An air outlet component is located near the second end and has an air outlet. A switched reluctance motor body is disposed in a housing and has an output shaft extending in a first direction, a rotor and a stator disposed around the output shaft, and a first end cover and a second end cover located at both ends of the rotor and the stator; A controller component, disposed within a housing and located in a first direction between the air intake component and the switched reluctance motor body, includes: The bracket, fixed in the housing, is mounted on the first end cover; and The motor drive board and the power rectifier board are arranged side-by-side on a bracket in a second direction perpendicular to the first direction; and The exhaust component is located on the output shaft and on the side of the switched reluctance motor body away from the controller component. At least one air duct is formed between the housing and the controller components and the switched reluctance motor body to dissipate heat from the controller components and the switched reluctance motor body. The housing includes a cavity at its second end for receiving the exhaust component. The at least one air duct includes a first air duct formed between the housing and the controller components and the stator, and a second air duct formed between the stator and the rotor. The first and second end caps have a hollowed-out design, and The diameter d3 of the opening at the second end of the housing is related to the outer diameter D of the switched reluctance motor body as d3 = 1.1 to 1.4D.

2. The switched reluctance motor according to claim 1, characterized in that, The bracket of the controller component is mounted on the first end cap, and the bracket is a rectangular frame with its plane parallel to the first direction.

3. The switched reluctance motor according to claim 1, characterized in that, The switched reluctance motor also includes a mounting plate, with the second end of the housing disposed on the mounting plate and the output shaft of the switched reluctance motor body passing through a hole in the mounting plate.

4. The switched reluctance motor according to claim 3, characterized in that, The air outlet component and the mounting plate are integrated into a single unit.

5. The switched reluctance motor according to claim 1, characterized in that, The air outlet component is mounted on the tubular wall of the outer casing.

6. The switched reluctance motor according to claim 1, characterized in that, The housing has multiple protrusions that project inward from its tubular wall and extend along a portion of the tubular wall for securing the switched reluctance motor body within the housing.

7. The switched reluctance motor according to claim 6, characterized in that, Multiple protrusions are evenly distributed circumferentially on the tubular wall.

8. The switched reluctance motor according to claim 1, characterized in that, The angle is in the range of 2° to 5°.

9. The switched reluctance motor according to claim 1, characterized in that, The angle is in the range of 3° to 4.5°.

10. The switched reluctance motor according to claim 1, characterized in that, The exhaust component includes multiple fan blades.

11. The switched reluctance motor according to claim 10, characterized in that, The height of the fan blade in the first direction is in the range of 4.5 mm to 7 mm.

12. The switched reluctance motor according to claim 1, characterized in that, The distance between the air intake component and the controller component along the first direction is in the range of 5mm to 20mm.

13. The switched reluctance motor according to claim 12, characterized in that, The distance is in the range of 8mm to 12mm.

14. The switched reluctance motor according to claim 1, characterized in that, The ratio of the air inlet area to the air outlet area of ​​the outer casing is between 1:3 and 1:1.

5.

15. The switched reluctance motor according to claim 1, characterized in that, The ratio of the air inlet area to the air outlet area of ​​the outer casing is between 1:2.5 and 1:

2.

16. An electric garden tool, characterized in that, The electric garden tool includes a switched reluctance motor as described in any one of claims 1 to 15.

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