Motor heat dissipation structure and axial flux permanent magnet synchronous motor

Abstract

The invention relates to the technical field of permanent magnet synchronous motors, in particular to a motor heat dissipation structure and an axial magnetic flux permanent magnet synchronous motor, permanent magnet rotors on two sides drive a heat dissipation disc to rotate synchronously, so that the heat dissipation disc rotates relative to PCB stators on two sides, and under the guidance of diversion heat dissipation grooves in two end surfaces of the heat dissipation disc, the heat dissipation disc is driven to rotate synchronously. Gas is driven to flow in the radial direction between the heat dissipation disc and the PCB stators on the two sides, and forced convection heat dissipation of the PCB stators on the two sides is achieved. On the premise that the axial height is not increased, the axial closed structure is not damaged and a conductive or magnetic interference part is not introduced, the surface heat exchange mode of the PCB stator is improved to a forced convection level from natural convection, and the working temperature rise of the PCB stator is reduced. Circulating heat exchange of air flow is completed in the closed machine shell, dust is prevented from directly entering an axial air gap, efficient heat exchange is conducted on the PCB stators on the two sides through the single rotating heat dissipation disc, the structure is simple and compact, and additional energy loss is low.

Description

Technical Field

[0001] This invention relates to the technical field of permanent magnet synchronous motors, and particularly to a motor heat dissipation structure and an axial flux permanent magnet synchronous motor. Background Technology

[0002] Axial flux permanent magnet synchronous motors (ACPMs) are characterized by their flatness, high power density, and high torque density, making them highly advantageous in space- and weight-sensitive applications. Printed circuit board (PCB) stators, with their high winding precision and small axial thickness, are widely used in these thin ACPMs, particularly suitable for applications with stringent axial space requirements, such as robot joints and drone electric drives. However, ACPMs typically employ a dual-rotor structure (i.e., an arrangement of "permanent magnet rotor 1 - stator - permanent magnet rotor 2") to counteract the uneven axial magnetic pull generated by a single-sided permanent magnet. This structure places the stator at the innermost part of the assembly, limiting its usable area for heat exchange and restricting heat dissipation. Simultaneously, the copper losses of the PCB stator are highly concentrated within the thin structure, further exacerbating the heat dissipation bottleneck.

[0003] Currently, common heat dissipation methods mainly fall into the following categories, but each has its limitations: Using fans or external air ducts for forced convection can compromise axial sealing, easily introduce dust, and generate noise. Relying on the shell for heat conduction and side heat sinks for passive heat dissipation, its heat transfer coefficient is low and it is difficult to eliminate local hot spots; Heat dissipation can be improved by drilling large holes or laying copper on the PCB stator, but the improvement in heat transfer is limited and may interfere with the magnetic circuit design. Summary of the Invention The purpose of this invention is to provide a motor heat dissipation structure and an axial flux permanent magnet synchronous motor to solve one or more technical problems existing in the prior art, and at least provide a beneficial option or create conditions.

[0004] According to a first aspect of the present invention, a motor heat dissipation structure includes: A rotor assembly comprising at least two permanent magnet rotors spaced apart along an axial direction; A stator assembly includes at least two PCB stators, which are axially spaced between two adjacent permanent magnet rotors; A heat dissipation assembly includes a heat sink, which is disposed between the two PCB stators. The heat sink is coaxially fixed with the permanent magnet rotor so that the heat sink rotates synchronously with the permanent magnet rotor. The heat sink has multiple circumferentially spaced heat dissipation grooves on its two end faces facing the two PCB stators. The heat dissipation grooves are used to drive gas to flow radially between the heat sink and the PCB stators as the heat sink rotates relative to the PCB stators.

[0005] The motor heat dissipation structure according to embodiments of the present invention has at least the following beneficial effects: During operation, the permanent magnet rotors on both sides drive the heat sink to rotate synchronously, causing the heat sink to rotate relative to the PCB stators on both sides. Guided by the heat dissipation grooves on both ends of the heat sink, the gas is driven to flow radially between the heat sink and the PCB stators on both sides, achieving forced convection heat dissipation for the PCB stators on both sides. This invention, without increasing the axial height, destroying the axially sealed structure, or introducing conductive or magnetic interference components, upgrades the surface heat exchange mode of the PCB stator from natural convection to forced convection, significantly reducing the operating temperature rise of the PCB stator. The airflow completes the circulating heat exchange within the sealed housing, preventing dust from directly entering the axial air gap, thus balancing environmental sealing and acoustic performance. The single rotating heat sink simultaneously performs efficient heat exchange on both PCB stators, resulting in a simple and compact structure with low additional energy loss.

[0006] According to some embodiments of the present invention, the plurality of the heat dissipation grooves are arranged in a spiral along the radial direction of the heat sink.

[0007] According to some embodiments of the present invention, the heat dissipation channel is an Archimedean spiral groove structure.

[0008] According to some embodiments of the present invention, one end of the heat dissipation channel extends to the outer edge of the heat sink, and the other end is disposed near the center of the heat sink, so as to drive the gas to form a directional inward flow from the outside to the inside.

[0009] According to some embodiments of the present invention, the gas flow cross-sectional area of ​​the heat dissipation channel is varied radially.

[0010] According to some embodiments of the present invention, the PCB stator has multiple vent holes distributed near the center.

[0011] According to some embodiments of the present invention, the stator assembly further includes a motor rotor shaft, which is coaxially and fixedly connected to the permanent magnet rotor and the heat sink, respectively, and the center of the PCB stator is provided with a stator shaft hole for the motor rotor shaft to pass through.

[0012] According to some embodiments of the present invention, the heat sink is made of a non-conductive and non-magnetic material.

[0013] According to some embodiments of the present invention, the heat dissipation grooves on both ends of the heat sink are arranged in a mirror-symmetrical manner.

[0014] According to a second aspect of the present invention, an axial flux permanent magnet synchronous motor includes the aforementioned motor heat dissipation structure and a housing. The heat dissipation plate, the permanent magnet rotor, and the PCB stator are all disposed within the housing. The PCB stator is fixedly connected to the housing, and the heat dissipation plate and the permanent magnet rotor are rotatably connected to the housing via a motor rotor shaft.

[0015] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. Attached Figure Description

[0016] The present invention will be further described below with reference to the accompanying drawings and embodiments; Figure 1 This is an exploded view of an embodiment of the motor heat dissipation structure provided by the present invention; Figure 2 This is a cross-sectional view of an embodiment of the motor heat dissipation structure provided by the present invention. Figure 3 yes Figure 2 A magnified view of part A in the middle; Figure 4 This is a schematic diagram of an embodiment of the heat sink provided by the present invention; Icon labels: First permanent magnet rotor 100; rotor back plate 110; permanent magnet 120; rotor shaft hole 130; rotor connecting hole 140; Second permanent magnet rotor 200; First PCB stator 300; stator shaft hole 310; vent hole 320; Second PCB stator 400; Electromagnetic air gap 500; Heat sink 600; heat sink shaft hole 610; heat sink connection hole 620; airflow cooling groove 630; Air film micro-gap 700; Motor rotor shaft 800; connecting flange structure 810. Detailed Implementation

[0017] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0018] In the description of this invention, it should be understood that the orientation descriptions, such as up, down, etc., are based on the orientation or positional relationship shown in the drawings and are only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0019] In the description of this invention, "multiple" refers to two or more. The use of "first" and "second" is for distinguishing technical features only and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or the order in which the indicated technical features are presented.

[0020] In the description of this invention, unless otherwise explicitly defined, terms such as "setting," "installing," and "connecting" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this invention in conjunction with the specific content of the technical solution.

[0021] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described below are some embodiments of the present invention, not all embodiments.

[0022] Existing axial flux permanent magnet synchronous motors have the following limitations in their heat dissipation design: forced convection using fans or external air ducts can disrupt the axially sealed structure, easily introducing dust and generating noise; passive heat dissipation relying on shell heat conduction and lateral heat sinks has a low heat transfer coefficient and is difficult to eliminate local hot spots; while large-area perforations or copper plating on the PCB stator can improve heat dissipation, the effect is limited and can interfere with the magnetic circuit. Therefore, this invention proposes a novel motor heat dissipation structure. This structure, without increasing the motor's axial height, disrupting axial sealing, or introducing conductive or magnetic interference components, can significantly improve the convective heat transfer coefficient on the PCB stator surface, effectively reducing stator temperature rise and hot spot temperatures, while simultaneously achieving effective control of increased aerodynamic losses and noise.

[0023] Reference Figures 1-4 The present invention provides the following embodiment of the motor heat dissipation structure: The motor heat dissipation structure of the present invention includes: a rotor assembly, a stator assembly, and a heat dissipation assembly.

[0024] Among them, such as Figure 1 and Figure 2 As shown, the rotor assembly of the present invention includes at least two permanent magnet rotors spaced apart along the axial direction. In this embodiment, two permanent magnet rotors are provided, namely a first permanent magnet rotor 100 and a second permanent magnet rotor 200. The permanent magnet rotor of this embodiment includes a rotor back plate 110 and a plurality of permanent magnets 120 spaced apart along the circumferential direction.

[0025] The stator assembly of the present invention includes at least two PCB stators. This embodiment provides two PCB stators, namely a first PCB stator 300 and a second PCB stator 400. The first PCB stator 300 and the second PCB stator 400 are axially spaced between the first permanent magnet rotor 100 and the second permanent magnet rotor 200. Figure 3 As shown, an electromagnetic air gap 500 is formed between the PCB stator and the permanent magnet rotor. The first PCB stator 300 is opposite to the first permanent magnet rotor 100 and generates an electromagnetic effect to drive the first permanent magnet rotor 100 to rotate. The second PCB stator 400 is opposite to the second permanent magnet rotor 200 and generates an electromagnetic effect to drive the second permanent magnet rotor 200 to rotate.

[0026] like Figure 1 and Figure 2 As shown, the heat dissipation assembly of the present invention includes at least one heat sink 600. The heat sink 600 is a thin, non-conductive, and non-magnetic disk structure. Specifically, this embodiment provides one heat sink 600, which is disposed between the first PCB stator 300 and the second PCB stator 400. The heat sink 600 is coaxially and fixedly disposed with respect to the permanent magnet rotor, so that the heat sink 600 rotates synchronously with the permanent magnet rotor. Figure 3 As shown, air film gaps 700 are formed between the heat sink 600 and the first PCB stator 300 and the second PCB, respectively.

[0027] Regarding the connection between the heat sink 600 and the permanent magnet rotor, the stator assembly in this embodiment also includes a motor rotor shaft 800. The motor rotor shaft 800 is coaxially and fixedly connected to the permanent magnet rotor and the heat sink 600 respectively. The center of the PCB stator is provided with a stator shaft hole 310 through which the motor rotor shaft 800 passes. An insulating barrier is provided between the stator shaft hole 310 and the motor rotor shaft 800. The center of the heat sink 600 in this embodiment is provided with a heat dissipation shaft hole 610, and a plurality of heat dissipation connection holes 620 are provided around the heat dissipation shaft hole 610 in a circumferential direction. The center of the permanent magnet rotor is also provided with a rotor shaft hole 130, and a plurality of rotor connection holes 140 are provided around the rotor shaft hole 130 in a circumferential direction. The motor rotor shaft 800 is provided with a connecting flange structure 810, which is used to connect with the heat dissipation connection holes 620 and the rotor connection holes 140 to form a rigid whole of "rotor-heat sink 600-rotor". The rotation direction of the heat sink 600 is defined by the rotation direction of the motor and is synchronized with the permanent magnet rotor.

[0028] In some other embodiments, the connection between the heat sink 600 and the permanent magnet rotor can be achieved through other components.

[0029] like Figure 1 and Figure 4As shown, the heat sink 600 of the present invention has a plurality of circumferentially spaced heat dissipation grooves 630 on both end faces of the first PCB stator 300 and the second PCB stator 400. The heat dissipation grooves 630 are used to drive gas to flow radially in the air film micro-gap 700 between the heat sink 600 and the PCB stator when the heat sink 600 rotates relative to the PCB stator.

[0030] In operation, the first PCB stator 300 and the second PCB stator 400 are energized, driving the first permanent magnet rotor 100 and the second permanent magnet rotor 200 to rotate, thereby causing the heat sink 600 to rotate synchronously relative to the first PCB stator 300 and the second PCB stator 400. Guided by the heat dissipation grooves 630 on both ends of the heat sink 600, gas is driven to flow radially through the air film micro-gap 700 between the heat sink 600 and the two PCB stators, achieving forced convection heat dissipation for the first PCB stator 300 and the second PCB stator 400.

[0031] like Figure 4 As shown, in this embodiment, multiple heat dissipation channels 630 are spirally arranged along the radial direction of the heat dissipation plate 600, and one end of the heat dissipation channel 630 extends to the outer edge of the heat dissipation plate 600, while the other end is located near the center of the heat dissipation plate 600, so as to drive the gas to form a directional inward flow from the outside to the inside. In this embodiment, by setting a circumferential air inlet annular slot on the outer diameter side and a circumferential air outlet annular slot on the inner diameter side, and with a shallow labyrinth seal, the air forms a directional inward flow from the outside to the inside along the plate surface within the air film micro-gap 700 on both sides, thereby achieving axially closed forced convection heat dissipation.

[0032] Furthermore, in this embodiment, the heat dissipation channel 630 is an Archimedean spiral groove structure, and the heat dissipation channels 630 on both ends of the heat sink 600 are arranged in a mirror symmetrical manner.

[0033] Furthermore, the cross-sectional area of ​​the airflow in the heat dissipation channel 630 varies radially to match the flow distribution. The cross-sectional area of ​​the airflow in the heat dissipation channel 630 can be gradually reduced along the airflow direction to increase the speed of airflow.

[0034] In other embodiments, the heat dissipation channel 630 may be other forms of channel structure, and may drive gas to form a directional outflow from the inside to the outside.

[0035] Furthermore, such as Figure 1 and Figure 3As shown, in this embodiment, the first PCB stator 300 and the second PCB stator 400 have multiple air holes 320 distributed near the center. The air holes 320 connect the electromagnetic air gap 500 and the air film microgap 700. After air enters from the outer edge laterally, it fills the air film microgap 700 on both sides. Under the guidance of the heat dissipation groove 630, it is transported from the outside to the inside in a centripetal manner. It passes through the air holes 320 and penetrates the respective side PCB stator, and then leaves through the electromagnetic air gap 500.

[0036] In some other embodiments, the electromagnetic air gap 500 and the air film microgap 700 are connected at their outer edges to create a circulating flow effect.

[0037] Regarding the specific form of the motor heat dissipation structure, the present invention provides a specific embodiment below, wherein the permanent magnet 120 of the present invention covers a radial range of […]. , ],in The outer diameter of the PCB stator, permanent magnet rotor, and heat sink must be less than or equal to 600 mm. The inner diameter of the PCB stator, permanent magnet rotor, and heat sink should be greater than or equal to 600 mm to meet the required magnetic pole coverage.

[0038] In this embodiment, the first PCB stator 300 and the second PCB stator 400 are respectively fixed inside the housing, forming a heat exchange plane opposite to the heat sink 600, and their effective heat exchange range is […]. , ].

[0039] In this embodiment, the thickness of the air film microgap 700 formed between the heat sink 600 and the PCB stator is... The thickness of the electromagnetic air gaps on both sides is 500. Furthermore, it does not directly interfere with the heatsink 600. The heat dissipation channel 630 is... It is radially connected nearby, directly communicating with the outer flow area and the air film microgap 700, but isolated from the electromagnetic air gap 500.

[0040] The heat sink 600 has a central connection and mounting area, in which a heat dissipation shaft hole 610 and multiple heat dissipation connection holes 620 are located. The inner end of the heat dissipation channel 630 extends to the outer edge of the connection and mounting area, and the outer radius of the heat sink 600 is [missing information]. The radius of the heat dissipation shaft hole 610 in the connection mounting area is The axial thickness of the 600 heat sink is .

[0041] The upper surface of the heat sink 600 is on [ , Evenly distributed across the area The heat dissipation channel 630 is defined by the Archimedean spiral function type_s, which can be expressed as: Its geometry is determined by the number of turns of the spiral. The initial and final positions of the spiral are respectively and Ensure along The rotation direction generates centripetal transport from the outer diameter to the inner diameter.

[0042] The cross-section of the heat dissipation channel 630 is rectangular, trapezoidal, or a composite rounded corner cross-section, and the channel opening width is [missing information]. The depth of the trench is The width of the ridge is = , forming the pitch = One-dimensional or two-dimensional variable pitch can be set along the radial direction, so that the cross-sectional area of ​​the groove changes with the radius to match the flow distribution.

[0043] The heat dissipation channels 630 on the lower surface of the heat sink 600 are geometrically mirrored relative to the upper surface, so that when viewed from below, they also form a centripetal transport from the outer diameter to the inner diameter. The heat dissipation channels 630 on both sides can use the same... , , , , as well as To achieve bilateral symmetry.

[0044] Among them, and The adjacent area can be set to import / export transition sections, and the transition section slot corners can be configured. With trench depth Can be pressed by function , Smooth the changes to reduce local pressure loss at the inlet and outlet.

[0045] At the outer edge r≈ The air intake is located at the side of the slot, forming a circumferential edge gap, allowing air to enter from the outside. The air film micro-gap 700 enters radially on both sides. The geometry of the lateral air intake only changes the radial clearance of the outer circle edge, without introducing additional steps or gaps in the axial direction, thus not increasing the total axial thickness.

[0046] In r≈ At the same location, multiple vent holes 320 arranged in a circumferential array are respectively arranged on the first PCB stator 300 and the second PCB stator 400. The vent holes 320 are non-electrical functional holes, and the annular distribution angle position is such that the copper foil and traces around the holes are left with an electrical safety distance. The vent holes 320 can be designed to be non-metallic or selectively metallized but have no electrical connection.

[0047] Working principle of motor heat dissipation structure: After air enters from the outer edge laterally, it fills the air film micro-gap 700 on both sides, and is guided by the airflow cooling grooves 630 on both sides. Towards In-plane centripetal transport occurs. Due to the symmetry of the upper and lower guide cooling slots 630, the main flow of the two film cooling micro-gap 700 independently completes heat exchange and transport within their respective planes, with the end at r ≈ The gas enters through the vent 320 and penetrates the PCB stator on each side, then exits through the electromagnetic air gap 500. The gas inlet / outlet and leakage path are limited to the vent 320 along the outer edge and inner edge, thus maintaining directional transport with minimal axial cost. If necessary, this can be achieved by adjusting { , , , , Achieve parameterized balance of inlet and outlet flow resistance.

[0048] The present invention also proposes an axial flux permanent magnet synchronous motor, including the above-mentioned motor heat dissipation structure, and also including a housing (not shown in the figure). The heat dissipation plate 600, the permanent magnet rotor and the PCB stator are all disposed in the housing. The PCB stator is fixedly connected to the housing. The heat dissipation plate 600 and the permanent magnet rotor are rotatably connected to the housing through the motor rotor shaft 800.

[0049] Compared with the prior art, the present invention has the following advantages: High reliability: The airflow is guided within the disc surface and convective heat transfer is completed within the sealed casing, preventing dust from directly entering the axial air gap, and combining environmental sealing with good acoustic performance. High-efficiency flat heat dissipation: Without significantly increasing the axial height, the heat exchange mode of the stator surface is upgraded from natural convection to forced convection, which significantly reduces the stator temperature rise; Good electromagnetic compatibility: Both the heat sink 600 and the PCB stator are made of non-conductive and non-magnetic materials, which effectively avoids eddy current loss and magnetic field distortion. Dual-sided synchronous enhanced heat dissipation: The heat exchange of the PCB stators on both sides can be carried out efficiently at the same time through a single rotating heat sink 600. The structure is simple and compact with low additional loss.

[0050] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0051] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A motor heat dissipation structure, characterized in that, include: A rotor assembly comprising at least two permanent magnet rotors spaced apart along an axial direction; A stator assembly includes at least two PCB stators, which are axially spaced between two adjacent permanent magnet rotors; A heat dissipation assembly includes a heat sink, which is disposed between the two PCB stators. The heat sink is coaxially fixed with the permanent magnet rotor so that the heat sink rotates synchronously with the permanent magnet rotor. The heat sink has multiple circumferentially spaced heat dissipation grooves on its two end faces facing the two PCB stators. The heat dissipation grooves are used to drive gas to flow radially between the heat sink and the PCB stators as the heat sink rotates relative to the PCB stators.

2. The motor heat dissipation structure according to claim 1, characterized in that: The plurality of the heat dissipation grooves are arranged in a spiral along the radial direction of the heat sink.

3. The motor heat dissipation structure according to claim 2, characterized in that: The heat dissipation channel is an Archimedes spiral groove structure.

4. The motor heat dissipation structure according to claim 3, characterized in that: One end of the heat dissipation channel extends to the outer edge of the heat sink, and the other end is located near the center of the heat sink, so as to drive the gas to form a directional inward flow from the outside to the inside.

5. The motor heat dissipation structure according to claim 4, characterized in that: The cross-sectional area of ​​the gas flow channel in the heat dissipation channel varies radially.

6. The motor heat dissipation structure according to claim 1, characterized in that: The PCB stator has multiple vent holes distributed near the center.

7. The motor heat dissipation structure according to claim 1, characterized in that: The stator assembly also includes a motor rotor shaft, which is coaxially and fixedly connected to the permanent magnet rotor and the heat sink, respectively. The center of the PCB stator is provided with a stator shaft hole for the motor rotor shaft to pass through.

8. The motor heat dissipation structure according to claim 1, characterized in that: The heat sink is made of non-conductive and non-magnetic material.

9. The motor heat dissipation structure according to claim 1, characterized in that: The heat dissipation grooves on both ends of the heat sink are arranged in a mirror-symmetric manner.

10. An axial flux permanent magnet synchronous motor, characterized in that: The motor heat dissipation structure includes any one of claims 1 to 9, and further includes a housing. The heat dissipation plate, the permanent magnet rotor and the PCB stator are all disposed inside the housing. The PCB stator is fixedly connected to the housing. The heat dissipation plate and the permanent magnet rotor are rotatably connected to the housing through the motor rotor shaft.

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