Rotor structure of heat pipe cooling magnetic steel and flat wire motor thereof

Abstract

The invention relates to a rotor structure of a heat pipe cooling magnetic steel and a flat wire motor thereof, the rotor structure comprises a rotating shaft and a rotor core, the rotor core sleeves the rotating shaft, and the rotor core is in interference fit with the rotating shaft; the rotor core is also provided with a magnetic steel hole, a magnetic steel is fixed in the magnetic steel hole, at least one side of the magnetic steel is also provided with a heat conduction heat pipe, and two ends of the heat conduction heat pipe respectively extend out of the magnetic steel hole. On the basis that the overall performance of the motor is balanced, the shape of a traditional magnetic steel groove is optimized and adjusted, a heat pipe space capable of containing a heat conduction material is avoided, the heat conduction heat pipe is placed in the space, the heat conduction heat pipe makes direct contact with magnetic steel, and meanwhile the temperature heat dissipation efficiency in the axial direction is improved; moreover, the installation and arrangement of the heat-conducting heat pipe have little influence on the current magnetic steel insertion, integral skewed pole injection molding and other processes, and can be completely compatible with the current production line process.

Description

Technical Field

[0001] The present invention belongs to the technical field of flat wire motors, and particularly relates to a rotor structure for cooling a permanent magnet with a heat pipe and a flat wire motor thereof. Background Art

[0002] New energy vehicle drive motors pursue high power, low cost, and high reliability, and there are more and more solutions for oil-cooled flat wire motors; currently, common stator oil circuits include oil pipe spraying, end oil ring spraying, and axial oil channels opened in the yoke of the stator core, etc.; however, relatively little attention has been paid to the cooling of the permanent magnet on the rotor side.

[0003] Currently, common rotor oil cooling solutions mainly include hollow shaft oil cooling, rotor weight reduction hole oil cooling, rotor permanent magnet slot oil cooling, etc., which belong to direct or indirect cooling of the permanent magnet under the oil cooling topology; for the above-mentioned mainstream rotor cooling solutions, either they belong to indirect cooling, and the temperature improvement of the main heat source on the rotor side - the permanent magnet is limited, which still restricts the application of the motor at higher speeds and higher power densities; or they belong to simple permanent magnet slot cooling, the rotor oil circuit is complex, the oil circuit sealing process on the high-speed rotor side is difficult, and the reliability is poor; at the same time, after cooling with the permanent magnet slot, the original permanent magnet injection molding process has poor matching compatibility; therefore, there is an urgent need for a rotor permanent magnet cooling solution that can dissipate heat from the permanent magnet more efficiently, reduce the temperature of the permanent magnet, while being more process-friendly and reliable, making less changes to the current rotor oil circuit, and being more compatible with the current process! Summary of the Invention

[0004] In order to solve the above technical problems, the first object of the present invention is to provide a rotor structure for cooling a permanent magnet with a heat pipe, which has high heat dissipation efficiency, helps to improve the performance of the motor, and is convenient for production and processing; the second object of the present invention is to provide a flat wire motor.

[0005] In order to achieve the first object of the above invention, the present invention adopts the following technical solutions:

[0006] A rotor structure for cooling a permanent magnet with a heat pipe, including a rotating shaft and a rotor core, the rotor core is sleeved on the rotating shaft, and the rotor core is in interference fit with the rotating shaft; a permanent magnet hole is further opened on the rotor core, a permanent magnet is fixed in the permanent magnet hole, and at least one side of the permanent magnet is further provided with a heat conducting heat pipe, and both ends of the heat conducting heat pipe respectively extend out of the permanent magnet hole.

[0007] As a preferred solution: the rotor core includes multiple groups of single-stack cores, and a heat conducting heat pipe is fixed in the permanent magnet hole of each single-stack core, and the heat conducting heat pipes in the single-stack cores at both ends extend out of the permanent magnet hole.

[0008] As a preferred solution: baffles are further provided at both ends of the rotor core, the baffles are also sleeved on the rotating shaft and are in interference fit with the rotating shaft, an oil storage cavity is provided in the baffles, and the end of the heat conducting heat pipe extends into the oil storage cavity of the baffles.

[0009] As a preferred solution: an inner oil hole is provided on the inner wall of the baffle; the inside of the rotating shaft is hollow and one end is open to form a central axial oil passage; an oil hole is further provided on the side wall of the rotating shaft; and an axial keyway hole communicating the oil hole with the inner oil hole is provided on the inner wall of the rotor core.

[0010] As a preferred solution: the single-stack cores on both sides of the middle of the rotating shaft are circumferentially deflected by 45°; the oil holes on the side wall of the rotating shaft are arranged in two rows and are respectively aligned and communicated with the axial keyway holes of the corresponding single-stack cores.

[0011] As a preferred solution: an oil-slinging hole is provided on the outer wall of the baffle; the position of the oil-slinging hole is aligned with the position of the inner oil hole; and a plurality of retaining bars are further arranged on the baffle at intervals, and the gaps between the plurality of retaining bars are misaligned with the position of the oil-slinging hole.

[0012] As a preferred solution: positioning notches are further provided at both ends of the magnet on the magnet hole; the heat-conducting heat pipe is inserted into the positioning notches and is in close contact with the magnet.

[0013] As a preferred solution: multiple groups of single-stack cores are deflected relative to each other, and the deflection directions of the multiple single-stack cores on one side of the middle of the rotating shaft are opposite to the deflection directions of the multiple single-stack cores on the other side of the middle of the rotating shaft.

[0014] As a preferred solution: a shaft shoulder is further provided at one end of the rotating shaft, and the baffle abuts against the shaft shoulder.

[0015] In order to achieve the second object of the above invention, the present invention adopts the following technical solutions:

[0016] A flat wire motor includes a motor housing, a stator and a rotor. The stator is fixed in the motor housing, the rotor is arranged in the stator and is rotatably connected to the motor housing, and the rotor adopts the rotor structure of a heat pipe cooling magnet as described in any one of the above.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0018] On the basis of balancing the overall performance of the motor, the present invention optimizes and adjusts the shape of the traditional magnet slot, creates a heat pipe space that can place a heat-conducting material, places a heat-conducting heat pipe through this space, directly contacts the magnet while improving the temperature dissipation efficiency in the axial direction; and the installation and arrangement of the heat-conducting heat pipe have little influence on the current processes such as inserting magnets and integral skew pole injection molding, and can be fully compatible with the current production line processes. Description of the Drawings

[0019] The specification drawings forming a part of this application are used to provide a further understanding of this application. The schematic embodiments of this application and their descriptions are used to explain this application and do not constitute a limitation to this application.

[0020] Figure 1 is the overall structural schematic diagram of the present invention;

[0021] Figure 2 is the schematic diagram of the corresponding coolant flow domain of the rotor structure of the present invention;

[0022] Figure 3 is the explosion structural schematic diagram of the present invention;

[0023] Figure 4 is the structural schematic diagram of the rotor core of the present invention;

[0024] Figure 5 is the structural schematic diagram after inserting heat-conducting heat pipes and permanent magnets into the single-stack core of the present invention;

[0025] Figure 6 is the end-face structural schematic diagram of the single-stack core of the present invention;

[0026] Figure 7 is the explosion structural schematic diagram of the single-stack core, heat-conducting heat pipe and permanent magnet of the present invention;

[0027] Figure 8 is the structural schematic diagram of the rotating shaft of the present invention;

[0028] Figure 9 is the structural schematic diagram of the baffle of the present invention.

[0029] The reference numerals are: 1, rotating shaft; 10, middle axial oil passage; 11, oil hole; 12, shaft shoulder; 2, rotor core; 21, single-stack core; 22, permanent magnet; 23, heat-conducting heat pipe; 210, permanent magnet hole; 211, axial keyway hole; 212, positioning notch; 3, baffle; 30, inner oil hole; 31, oil slinger hole; 32, retaining bar. Detailed Description of the Invention

[0030] It should be noted that the following detailed descriptions are all illustrative and are intended to provide further explanations for the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present application belongs.

[0031] It should be noted that the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "include" and / or "comprise" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0032] In addition, in the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "clockwise", "counterclockwise", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention.

[0033] In addition, the terms "first" and "second" are only used for descriptive purposes and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise specified, the meaning of "a plurality" is two or more, unless otherwise clearly defined.

[0034] In the present invention, unless otherwise clearly specified and defined, the terms "mounted", "connected", "connected to", "fixed", etc. should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0035] In the present invention, unless otherwise clearly specified and defined, the first feature being "above" or "below" the second feature may include the direct contact between the first and second features, or may include the situation where the first and second features are not in direct contact but in contact through other features between them. Moreover, the first feature being "above", "over" and "on top of" the second feature includes that the first feature is directly above and obliquely above the second feature, or merely indicates that the horizontal height of the first feature is higher than that of the second feature. The first feature being "below", "beneath" and "under" the second feature includes that the first feature is directly below and obliquely below the second feature, or merely indicates that the horizontal height of the first feature is lower than that of the second feature.

[0036] The present invention will be further described below with reference to the drawings and embodiments:

[0037] As Figure 1 、 Figures 3 to 5As shown in the figure, a rotor structure of a heat pipe-cooled magnet includes a rotating shaft 1 and a rotor core 2. The rotor core 2 is sleeved on the rotating shaft 1, and the rotor core 2 is in interference fit with the rotating shaft 1. A magnet hole 210 is also provided on the rotor core 2, and a magnet 22 is fixed in the magnet hole 210. At least one side of the magnet 22 is also provided with a heat-conducting heat pipe 23, and both ends of the heat-conducting heat pipe 23 extend out of the magnet hole 210 respectively. The specific fixing method of the heat-conducting heat pipe 23 is as follows: positioning notches 212 are provided at both ends of the magnet 22 on the magnet hole 210, and the heat-conducting heat pipe 23 is inserted into the positioning notches 212 and is in close contact with the magnet 22.

[0038] The heat-conducting heat pipe is made of aluminum nitride (AlN) ceramic, silicon carbide (SiC) ceramic or boron nitride (BN) ceramic. Aluminum nitride (AlN) ceramic: It has a high thermal conductivity, and the theoretical thermal conductivity can reach 320 W / (m·K). At the same time, it has excellent electrical insulation performance, low dielectric constant and dielectric loss, good chemical stability, and relatively high mechanical strength. Silicon carbide (SiC) ceramic: Its thermal conductivity is as high as 270 W / (m·K), with high strength, high hardness, good wear resistance and chemical stability, outstanding high-temperature resistance performance, and can maintain excellent heat conduction performance under high-temperature and high-load conditions. Boron nitride (BN) ceramic: The crystal structure of hexagonal boron nitride is similar to that of graphite, and the in-plane thermal conductivity coefficient reaches 180 - 200 W / (m·K). It has high insulation, low dielectric constant, low dielectric loss and high thermal stability, and an extremely low coefficient of thermal expansion.

[0039] The present invention proposes a new magnet slot design for the magnet slot shape under the dimension of heat dissipation of the "heat pipe layout" temperature field, and synchronously optimizes the shape, size, etc. of the heat pipe layout at the beginning of the punching design; optimizes the space in the magnet slot that can place the high-thermal-conductivity ceramic material heat pipe; the heat pipe is in close contact with the rectangular corner area where the magnet generates heat and demagnetizes most severely, and at the same time plays the function of fixing the magnet to prevent it from moving.

[0040] As Figures 4 to 7 shown in the figure, the rotor core 2 includes multiple groups of single-stack cores 21. A heat-conducting heat pipe 23 is fixed in the magnet hole 210 of each single-stack core 21, and the heat-conducting heat pipes 23 in the single-stack cores 21 at both ends extend out of the magnet hole 210. Baffles 3 are also provided at both ends of the rotor core 2. The baffles 3 are also sleeved on the rotating shaft 1 and are in interference fit with the rotating shaft 1. A shaft shoulder 12 is provided at one end of the rotating shaft 1, and the baffle 3 abuts against the shaft shoulder 12. An oil storage cavity is provided in the baffle 3, and the end of the heat-conducting heat pipe 23 extends into the oil storage cavity of the baffle 3.

[0041] An inner oil hole 30 is provided on the inner wall of the baffle 3. The inside of the rotating shaft 1 is hollow and one end is open to form a central axial oil passage 10. An oil hole 11 is also provided on the side wall of the rotating shaft 1. An axial keyway hole 211 communicating the oil hole 11 with the inner oil hole 30 is formed on the inner wall of the rotor core 2.

[0042] The single-stack cores 21 on both sides of the middle of the rotating shaft 1 are circumferentially deflected by 45°. And the multiple groups of single-stack cores 21 on both sides of the middle of the rotating shaft 1 are sequentially deflected clockwise from the middle to both ends. 4 axial keyway holes 211 are equidistantly arranged at intervals along the circumferential direction on each single-stack core 21. The adjacent axial keyway holes 211 are communicated with each other, and the outermost axial keyway hole 211 is communicated with the inner oil hole 30. The above structure enables the axial keyway holes 211 to stagger and flow oil unidirectionally towards the end face. The oil holes 11 on the side wall of the rotating shaft 1 are in two rows, which are respectively aligned and conducted with the axial keyway holes 211 of the corresponding single-stack cores 21, as Figure 8 shown.

[0043] Although the heat-conducting heat pipes between the single-stack cores are discrete and non-continuous as a whole in the axial direction, precisely due to factors such as skewed poles, the heat-conducting heat pipes can still contact the magnets or the rotor core of the adjacent stack, and still have good axial heat transfer efficiency.

[0044] The rotor oil passage is ejected from the central hole of the rotating shaft to the axial keyway holes where the rotor core and the rotating shaft are matched; the two stacks of single-stack cores in the middle rotate by 45° mechanical angle circumferentially, forming oil passages with respective half-axial lengths that are symmetric front and back but not through; combined with the design of the two rows of oil holes on the rotating shaft, an oil passage with symmetric and balanced flow resistance is formed at the geometric center of the rotor core, and then the oil flow rates of the front and rear end oil ejection are also balanced.

[0045] As Figure 9 shown, an oil ejection hole 31 is provided on the outer wall of the baffle 3. The position of the oil ejection hole 31 is aligned with the position of the inner oil hole 30. Multiple blocking strips 32 are also provided on the baffle 3 at intervals. The gaps between the multiple blocking strips 32 are misaligned with the position of the oil ejection hole 31.

[0046] The above structure can enable the cooling oil in the axial keyway holes 211 of the rotor to be radially guided by the baffle, and the oil is ejected by centrifugal force at the outer diameter of the baffle to cool the end of the winding; at the same time, 2 layers of circumferential annular oil storage grooves are formed radially inside the baffle, and a closed oil storage space is formed by cooperating with the end face of the rotor core. The two layers of oil storage grooves respectively correspond to the heat-conducting heat pipe parts protruding from the ends of the large and small magnets, so that the flowing low-temperature cooling oil can perform convective heat transfer on the heat pipes, reduce the temperature of the heat pipes, and then reduce the temperature of the magnets in the core. The flow domain of the coolant of the rotor of the present invention is as Figure 2 shown.

[0047] Based on the balance of the overall performance of the motor, the present invention optimizes and adjusts the shape of the traditional magnet slot to create a heat pipe space for placing heat-conducting materials. By placing a heat pipe made of a heat-conducting material in this space, while directly contacting the magnet, the temperature dissipation efficiency in the axial direction is improved.

[0048] The production and processing technology of the present invention is friendly. The heat pipe is simple to process and form, with a moderate cost, and has little impact on the existing technology, being fully compatible with the current production line processes such as rotor injection molding and integral magnetization. At the same time, the heat pipes at the front and rear end faces protrude 1 mm and are recessed in the oil storage space formed by the baffle and the iron core end face. Utilizing the current rotor oil circuit cooling topology, while the rotor baffle throws oil, the heat pipes are cooled, thereby improving the cooling effect of the magnet. At the same time, the rotor punching sheet is single. Through methods such as staggered stacking, the flow resistance of the front and rear rotor oil circuits is completely symmetric and balanced, resulting in a small oil passage flow resistance, a small burden on the oil pump, and a high degree of oil circuit balance, providing a solution that balances cost, process, and performance for improving the temperature of the magnet of the flat wire motor for new energy vehicles.

[0049] A flat wire motor, comprising a motor housing, a stator, and a rotor. The stator is fixed inside the motor housing, the rotor is arranged inside the stator and is rotatably connected to the motor housing. The rotor adopts a rotor structure for cooling the magnet with a heat pipe as described in any one of the above.

[0050] In summary, compared with a motor with a conventional structure of the same specification, the motor adopting the rotor structure of the present invention can reduce the maximum temperature of the magnet by about 10 °C; the peak power is increased by about 1.5%; the peak torque ripple is increased by about 0.1% - 0.2%; the THD of the no-load back electromotive force is increased by about 0.1% - 0.2%. At the same time, the structure of the present invention is fully compatible with the current rotor production processes (inserting magnets, stacking, integral magnetization, etc.), has little impact on the existing mature processes, and is convenient for processing and production.

[0051] In the description of this specification, the description referring to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0052] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Without departing from the principles and spirit of the present invention, those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention. Any simple modification, equivalent change, and modification made to the above embodiments based on the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A rotor structure of a heat pipe-cooled permanent magnet, comprising a rotating shaft (1) and a rotor core (2), wherein the rotor core (2) is sleeved on the rotating shaft (1), and the rotor core (2) is in interference fit with the rotating shaft (1); a permanent magnet hole (210) is further formed in the rotor core (2), and a permanent magnet (22) is fixed in the permanent magnet hole (210), and it is characterized in that: At least one side of the permanent magnet (22) is further provided with a heat-conducting heat pipe (23), and both ends of the heat-conducting heat pipe (23) extend out of the permanent magnet hole (210).

2. The rotor structure of a heat pipe-cooled permanent magnet according to claim 1, characterized in that: The rotor core (2) includes multiple groups of single-stack cores (21). A heat-conducting heat pipe (23) is fixed in the permanent magnet hole (210) of each single-stack core (21), and the heat-conducting heat pipes (23) in the single-stack cores (21) at both ends extend out of the permanent magnet holes (210).

3. The rotor structure of a heat pipe-cooled magnet steel according to claim 2, characterized in that: Baffles (3) are further provided at both ends of the rotor core (2). The baffles (3) are also sleeved on the rotating shaft (1) and are in interference fit with the rotating shaft (1). An oil storage cavity is provided in the baffle (3), and the end of the heat-conducting heat pipe (23) extends into the oil storage cavity of the baffle (3).

4. A rotor structure of a heat pipe-cooled permanent magnet, according to claim 3, characterized in that: Inner oil holes (30) are provided on the inner wall of the baffle (3). The inside of the rotating shaft (1) is hollow and one end is open to form a middle axial oil passage (10). Oil holes (11) are further provided on the side wall of the rotating shaft (1). Axial keyway holes (211) communicating the oil holes (11) with the inner oil holes (30) are provided on the inner wall of the rotor core (2).

5. A rotor structure of a heat pipe-cooled permanent magnet, according to claim 4, characterized in that: The single-stack cores (21) on both sides of the middle of the rotating shaft (1) are circumferentially deflected by 45°. The oil holes (11) on the side wall of the rotating shaft (1) are in two rows and are respectively aligned and communicated with the axial keyway holes (211) of the corresponding single-stack cores (21).

6. A rotor structure of a heat pipe-cooled magnet steel according to claim 3 or 4, characterized in that: Oil throwing holes (31) are provided on the outer wall of the baffle (3). The positions of the oil throwing holes (31) are aligned with the positions of the inner oil holes (30). Multiple retaining strips (32) are also provided on the baffle (3) at intervals. The gaps between the multiple retaining strips (32) are misaligned with the positions of the oil throwing holes (31).

7. The rotor structure of a heat pipe cooled permanent magnet according to claim 1, characterized in that: Positioning notches (212) are further provided at both ends of the permanent magnet (22) on the permanent magnet hole (210). The heat-conducting heat pipe (23) is inserted into the positioning notches (212) and is in close contact with the permanent magnet (22).

8. The rotor structure of a heat pipe-cooled permanent magnet according to claim 2, characterized in that: The multiple groups of single-stack cores (21) are deflected relative to each other, and the deflection directions of the multiple single-stack cores (21) on one side of the middle of the rotating shaft (1) are opposite to the deflection directions of the multiple single-stack cores (21) on the other side of the middle of the rotating shaft (1).

9. A rotor structure of a heat pipe-cooled permanent magnet, according to claim 3, characterized in that: A shoulder (12) is further provided at one end of the rotating shaft (1), and the baffle (3) abuts against the shoulder (12).

10. A flat wire motor, comprising a housing, a stator and a rotor, wherein the stator is fixed within the housing, the rotor is disposed within the stator and is rotatably connected to the housing, and is characterized in that: The rotor adopts a rotor structure for cooling a permanent magnet with a heat pipe according to any one of claims 1 to 9.

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