Inner rotor motor and game device

Abstract

The application discloses an inner rotor motor and a game device, and relates to the technical field of motors. The inner rotor motor comprises a stator assembly and a rotor assembly which are coaxially arranged, and the rotor assembly is sleeved in the stator assembly. Specifically, the stator assembly comprises a stator core and a stator winding. The stator core comprises a ring-shaped stator yoke and a plurality of stator teeth which are equidistantly distributed on the inner side of the ring-shaped stator yoke in the circumferential direction. The rotor assembly comprises a ring-shaped rotor core and a rotating shaft which is coaxially arranged in the rotor core. The outer circumferential surface of the rotor core is provided with a plurality of permanent magnets which are equidistantly distributed in the circumferential direction of the rotor core. An air gap with uneven thickness is formed between the stator teeth and the permanent magnets. The technical scheme provided by the application can reduce motor vibration noise and improve motor performance.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electric machines, in particular to an inner rotor electric machine and a game device. BACKGROUND

[0002] The game device at present generally adopts an inner rotor electric machine as a driving device. The traditional unit electric machine is a 12-slot 14-pole inner rotor permanent magnet brushless direct current electric machine, which has the characteristics of uniform air gap and high power density. However, due to the characteristic of uniform air gap, the inner rotor permanent magnet brushless direct current electric machine also has large cogging torque and low sinusoidal ratio, which further leads to higher tangential torque ripple of the inner rotor electric machine and thus generates larger vibration noise. In order to solve the problem of vibration noise, the traditional solution is to increase the air gap of the electric machine, so as to weaken the high-order harmonic in the air gap to cause vibration noise, so as to achieve the purpose of reducing vibration noise. However, the larger air gap also has problems. The air gap is too large, which leads to increased magnetic resistance and reduced magnetic flux, and thus leads to reduced back electromotive force and degraded performance of the electric machine. Based on the above reasons, there is an urgent need for an inner rotor electric machine which can reduce vibration noise and ensure the efficiency of the electric machine.

[0003] It should be noted that the above content is only used to assist in understanding the technical solutions of the present application, and does not represent the acknowledgement of the above content as prior art. SUMMARY

[0004] The main purpose of the present application is to provide an inner rotor electric machine and a game device, which can reduce vibration noise and ensure the efficiency of the electric machine.

[0005] In order to achieve the above purpose, the present application provides an inner rotor electric machine, which comprises a stator assembly and a rotor assembly arranged coaxially, the rotor assembly is sleeved in the stator assembly;

[0006] Specifically, the stator assembly comprises a stator core and a stator winding; the stator core comprises a ring-shaped stator yoke and a plurality of stator teeth which are distributed equidistantly along the circumference of the inner side of the stator yoke, and a stator slot is formed between any two adjacent stator teeth; the stator winding is wound on the stator teeth and penetrates the stator slot;

[0007] The rotor assembly comprises a ring-shaped rotor core and a rotating shaft arranged coaxially in the ring-shaped inner part of the rotor core; the outer circumferential surface of the rotor core is provided with a plurality of permanent magnets, and the plurality of permanent magnets are equidistantly distributed along the circumference of the rotor core;

[0008] Among them, the stator teeth and the permanent magnets form an air gap with uneven thickness.

[0009] In an embodiment, the first profile surface of the stator tooth towards the permanent magnet comprises a first line segment, an arc segment and a second line segment connected in sequence, wherein the first line segment and the second line segment are symmetrically arranged at two ends of the arc segment; wherein the interval between the arc segment and the second profile surface of the permanent magnet towards the stator tooth is kept equal, and is defined as a first air gap; the interval between the first line segment or the second line segment and the second profile surface is defined as a second air gap, and the first air gap is smaller than the second air gap.

[0010] In an embodiment, the number of the stator teeth is 12p, and the number of the permanent magnets is 14p; wherein p is a positive integer and p≥1.

[0011] In an embodiment, the width of the permanent magnet is defined as Mag, wherein Mag satisfies 0.5*(LCM(14p, 12p) / 360)*Dso≤Mag≤2*(LCM(14p, 12p) / 360)*Dso; wherein Dso is the diameter of the arc segment of the stator tooth, LCM(14p, 12p) is the least common multiple of the pole slot, Dso and Mag are in units of mm, and LCM(14p, 12p) is unitless.

[0012] In an embodiment, the slot opening width of the stator slot is defined as Wsl, wherein Wsl satisfies 3*sin(Dso / LCM(14p, 12p))≤Wsl≤15*sin(Dso / LCM(14p, 12p)); wherein Dso is the diameter of the arc segment of the stator tooth, LCM(14p, 12p) is the least common multiple of the pole slot, Dso and Wsl are in units of mm, and LCM(14p, 12p) is unitless.

[0013] In an embodiment, the angle of the arc segment is defined as An, wherein An satisfies 0<An<2π / (14p), and An is in units of radian.

[0014] In an embodiment, the distance of the first air gap is defined as δmin, and δmin satisfies 0.1≤δmin≤8*LCM(14p, 12p) / 360; wherein Dso is the diameter of the arc segment of the stator tooth, and LCM(14p, 12p) is the least common multiple of the pole slot.

[0015] In an embodiment, a side of the permanent magnet close to the rotor core is defined as a third profile surface, the second profile surface and the third profile surface are both circular arc surfaces, and the circular arc radius of the second profile surface is equal to that of the third profile surface; a center of a circle corresponding to the circular arc surface of the second profile surface is defined as O1, and a center of a circle corresponding to the circular arc surface of the third profile surface is defined as O2, O1 and O2 do not coincide with each other and are on the same radial line, wherein the distance between O1 and O2 is the radial distance between the second profile surface and the third profile surface, i.e. the thickness of the permanent magnet.

[0016] In an embodiment, the rotor core is provided with a plurality of concave mounting grooves equidistantly distributed along the circumference thereof, and the mounting grooves correspond to the permanent magnets one by one; the third profile surface of the permanent magnet closely fits the bottom of the mounting groove.

[0017] In an embodiment, the rotor assembly further comprises an outer protective layer arranged on the outer circumferential surface of the rotor core, and the outer protective layer covers the permanent magnet, the outer protective layer is used to prevent the permanent magnet from falling off the mounting groove due to excessive centrifugal force when the permanent magnet rotates; wherein the outer protective layer can adopt a metal ring structure or a non-metal injection integrated structure.

[0018] In an embodiment, the rotor core and the stator core are soft magnetic materials; the stator core is usually formed by a plurality of silicon steel sheets stacked in sequence.

[0019] The application also provides a game device comprising the above-mentioned internal rotor motor.

[0020] The application has the following beneficial effects:

[0021] It can be understood that, since the air gap is arranged between the stator assembly and the rotor assembly, when the internal rotor motor is powered, the first profile surface of the stator tooth and the second profile surface of the permanent magnet form fundamental wave magnetic density and other high-order harmonic magnetic density (collectively referred to as harmonic magnetic density) in the air gap, and through self-coupling and mutual coupling, a larger tangential torque is generated, causing a larger tangential torque pulsation; the traditional solution is to weaken the harmonic magnetic density peak value by increasing the air gap, so as to reduce the peak-to-peak value of the cogging torque and the waveform distortion rate of the back EMF, but the reduction of the harmonic magnetic density peak value also reduces the fundamental wave magnetic density peak value, which reduces the back EMF coefficient and the motor performance. Based on the above reasons, the application sets the air gap between the stator assembly and the rotor assembly as a non-uniform air gap, which can effectively weaken the larger tangential torque pulsation caused by the high-order harmonic magnetic density, thereby reducing the vibration and noise; at the same time, the fundamental wave magnetic density peak value remains unchanged, ensuring that the motor performance does not decrease significantly. BRIEF DESCRIPTION OF DRAWINGS

[0022] In order to make the technical solutions of the embodiments of the present application or the prior art clearer, the accompanying drawings needed in the embodiments or prior art description will be briefly introduced. Obviously, the accompanying drawings in the following description only need to be some embodiments of the present application, and other drawings can be obtained by those skilled in the art without any creative effort on the basis of these drawings.

[0023] Figure 1 Structure diagram of an embodiment of the internal rotor motor provided by the present application;

[0024] Figure 2 Structure diagram of a stator assembly in an embodiment of the internal rotor motor provided by the present application;

[0025] Figure 3 Structure diagram of a rotor assembly in an embodiment of the internal rotor motor provided by the present application;

[0026] Figure 4 Structure diagram of an air gap in an embodiment of the internal rotor motor provided by the present application;

[0027] Figure 5 Structure diagram of an outer protective layer (metallic ring structure) in an embodiment of the internal rotor motor provided by the present application;

[0028] Figure 6 Structure diagram of an outer protective layer (non-metallic injection molding integrated structure) in an embodiment of the internal rotor motor provided by the present application;

[0029] Figure 7 The present application provides an embodiment of the internal rotor motor in the stator slot under the combination of the slot width and the permanent magnet width, and the schematic diagram of the back EMF waveform distortion rate is shown.

[0030] Figure 8 The present application provides an embodiment of the internal rotor motor in the stator slot under the combination of the slot width and the permanent magnet width, and the schematic diagram of the cogging torque peak-to-peak value is shown.

[0031] Figure 9 The present application provides an embodiment of the internal rotor motor in the stator slot under the combination of the slot width and the permanent magnet width, and the schematic diagram of the back EMF coefficient is shown.

[0032] Explanation of reference signs:

[0033] 100, stator assembly; 200, stator core; 210, stator yoke; 220, stator tooth; 221, first profile surface; 2211, first line segment; 2212, arc segment; 2213, second line segment; 230, stator slot; 300, rotor assembly; 310, rotor core; 311, mounting slot; 320, rotating shaft member; 330, permanent magnet; 331, second profile surface; 332, third profile surface; 340, outer protective layer; 400, air gap;

[0034] The objectives, features and advantages of the present application will be further illustrated in conjunction with the embodiments, with reference to the accompanying drawings. DETAILED DESCRIPTION

[0035] The technical solutions in the present application will be described clearly and completely below in conjunction with the accompanying drawings in the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without any creative effort belong to the scope of protection of the present application.

[0036] It should be noted that if the present application involves directionality indication (such as up, down, left, right, front, back, etc.), the directionality indication is only used to explain the relative position relationship, movement condition, etc. between components in a certain posture (as shown in the drawings), if the certain posture changes, the directionality indication also changes accordingly.

[0037] In addition, it should be noted that the description involving "first", "second" and the like in the present application is only for the purpose of description, and cannot be understood as indicating or implying the relative importance of the indicated technical features or implicitly indicating the number of the indicated technical features. Therefore, the features limited by "first", "second" can explicitly or implicitly include at least one of the features. In addition, the technical solutions of each embodiment can be combined with each other, but it must be based on the fact that a person skilled in the art can realize it, when the combination of technical solutions appears contradictory or unachievable, it should be considered that the combination of technical solutions does not exist, and is not within the scope of protection required by the present application.

[0038] The game device at present generally adopts an inner rotor motor as a driving device, the traditional unit motor is a 12-slot 14-pole inner rotor permanent magnet brushless direct current motor, which has the characteristics of uniform air gap and high power density; but due to the characteristic of uniform air gap, the inner rotor permanent magnet brushless direct current motor also has larger cogging torque and lower sinusoidal rate, and further causes the inner rotor motor to have higher tangential torque ripple and thus generates larger vibration noise; in order to solve the problem of vibration noise, the traditional solution is to increase the air gap of the motor, and thus weaken the high-order harmonic in the air gap to cause vibration noise, so as to achieve the purpose of reducing vibration noise; but the larger air gap also has problems, and the air gap is too large to cause the increase of magnetic resistance and the decrease of magnetic flux, thus causing the decrease of back electromotive force and the decrease of motor performance.

[0039] In order to solve the above technical problems, the application provides an inner rotor motor.

[0040] Please refer to Figures 1 to 3 In an embodiment of the application, the inner rotor motor comprises a stator assembly 100 and a rotor assembly 300 coaxially arranged, and the rotor assembly 300 is sleeved in the stator assembly 100.

[0041] Specifically, the stator assembly 100 comprises a stator core 200 and a stator winding (not shown in the drawing); the stator core 200 comprises a stator yoke 210 in annular structure and a plurality of stator teeth 220 distributed equidistantly along the circumference on the inner side of the annular stator yoke 210, and a stator slot 230 is formed between any two adjacent stator teeth 220; the stator winding is wound on the stator teeth 220 and penetrates through the stator slot 230.

[0042] The rotor assembly 300 comprises a rotor core 310 in annular structure and a rotating shaft 320 coaxially arranged on the inner side of the annular rotor core 310; the outer circumferential surface of the rotor core 310 is provided with a plurality of permanent magnets 330, and the plurality of permanent magnets 330 are equidistantly distributed along the circumference of the rotor core 310.

[0043] Among them, the stator tooth 220 and the permanent magnet 330 form an air gap 400 with uneven thickness; that is, the first profile surface 221 of the stator tooth 220 facing the permanent magnet 330 and the second profile surface 331 of the permanent magnet 330 facing the stator tooth 220 form an air gap 400 with uneven thickness.

[0044] Due to the air gap 400 arranged between the stator assembly 100 and the rotor assembly 300, the first profile surface 221 of the stator tooth 220 and the second profile surface 331 of the permanent magnet 330 generate fundamental wave magnetic flux and other high-order harmonic magnetic flux (collectively referred to as harmonic magnetic flux) in the air gap 400 under the condition that the inner rotor motor is powered and operated, and a larger tangential torque is generated through self-coupling and mutual coupling, causing a larger tangential torque pulsation. The traditional solution is to weaken the harmonic magnetic flux peak value by increasing the air gap 400 to reduce the peak-to-peak value of the cogging torque and the waveform distortion rate of the back EMF, but the reduction of the harmonic magnetic flux peak value also reduces the fundamental wave magnetic flux peak value, which reduces the back EMF coefficient and the motor performance.

[0045] The present application sets the air gap 400 between the stator assembly 100 and the rotor assembly 300 as a non-uniform air gap, which can effectively weaken the larger tangential torque pulsation caused by high-order harmonic magnetic flux, reduce vibration and noise, and at the same time ensure that the fundamental wave magnetic flux peak value remains unchanged, so that the motor has a larger power density.

[0046] Specifically, referring to Figure 2 and Figure 4 , the first profile surface 221 includes a first line segment 2211, an arc segment 2212 and a second line segment 2213 connected in sequence, wherein the first line segment 2211 and the second line segment 2213 are symmetrically arranged at both ends of the arc segment 2212; the distance between the arc segment 2212 and the second profile surface 331 is kept equal and is defined as the first air gap δmin; the distance between the first line segment 2211 or the second line segment 2213 and the second profile surface 331 is defined as the second air gap δmax, and the first air gap δmin is smaller than the second air gap δmax. In this way, the air gap width mutation can be reduced, the stepwise mutation of the air gap permeance can be effectively suppressed, the back EMF distortion rate and the peak-to-peak value of the cogging torque of the inner rotor motor can be reduced, and at the same time, the inner rotor motor has a higher back EMF coefficient. The distance between the arc segment 2212 and the second profile surface 331 of the permanent magnet 330 is the minimum distance of the air gap 400 (the first air gap), i.e. the distance between the arc segment 2212 and the second profile surface 331 is smaller than the distance between the first line segment 2211 and the third line segment and the second profile surface 331 (the first air gap is smaller than the second air gap); so that the air gap 400 between the stator tooth 220 and the permanent magnet 330 forms a non-uniform air gap 400 with a narrow middle and wide ends.

[0047] Specifically, the number of stator teeth 220 is 12p, and the number of permanent magnets 330 is 14p; wherein p is a positive integer and p≥1.

[0048] As a preferred scheme of the above embodiment, referring to Figures 1 to 3A width of the permanent magnet 330 is defined as Mag, where Mag satisfies 0.5*(LCM(14p, 12p) / 360)*Dso≤Mag≤2*(LCM(14p, 12p) / 360)*Dso; where Dso is a diameter of the arc segment 2212 of the stator tooth 220, and LCM(14p, 12p) is a minimum pole-slot common multiple. A slot opening width of the stator slot 230 is defined as Wsl, where Wsl satisfies 3*sin(Dso / LCM(14p, 12p))≤Wsl≤15*sin(Dso / LCM(14p, 12p)); where Dso is the diameter of the arc segment 2212 of the stator tooth 220, and LCM(14p, 12p) is the minimum pole-slot common multiple; where Mag, Wsl, and Dso are in units of mm, and LCM(14p, 12p) is unitless.

[0049] In an embodiment, the back EMF coefficient of the conventional inner rotor motor is 115.68 V / krms, the back EMF waveform distortion rate is 5%, and the peak-peak value of the cogging torque is 87.6 mN*m; with reference to Figure 7 、 Figure 8 and Figure 9 wherein Figure 7 、 Figure 8 and Figure 9 are the back EMF waveform distortion rate MAP cloud map, the peak-peak value of the cogging torque MAP cloud map, and the back EMF coefficient MAP cloud map obtained through multiple electromagnetic simulation tests; when a relatively optimal parameter is selected, for example, Wsl is 2 mm and Mag is 9.3 mm, the back EMF coefficient is 115.68 V / krms, the back EMF waveform distortion rate is 1.06%, and the peak-peak value of the cogging torque is 26.08 mN*m; the peak-peak value of the cogging torque and the back EMF waveform distortion rate of the inner rotor motor of the present application are lower than those of the conventional motor, and the back EMF coefficient remains unchanged.

[0050] In an embodiment, with reference to Figure 2 An angle of the arc segment 2212 is defined as An, where An satisfies 0<An<2π / (14p), and An is in units of radians. Taking the 14-pole 12-slot inner rotor motor as an example, An satisfies 0<An<0.449 (in radian measure), that is, An satisfies 0<An<30° (in mechanical angle).

[0051] In an embodiment, with reference to Figure 4The minimum air gap δmin satisfies 0.1≤δmin≤8*LCM(14p, 12p) / 360; wherein LCM(14p, 12p) is a minimum pole slot common multiple, and δmin is in mm; the minimum air gap δmin and the minimum pole slot common multiple LCM(14p, 12p) are in a certain relationship to maintain a larger back electromotive force coefficient and reduce cogging torque. Taking a 14-pole 12-slot inner rotor motor as an example, the LCM(14p, 12p) value is 84, and the minimum air gap δmin satisfies 0.1≤δmin≤1.867, in mm.

[0052] In an embodiment, referring to Figure 3 The side of the permanent magnet 330 attached to the rotor core 310 is defined as a third profile surface 332, the second profile surface 331 and the third profile surface 332 are both circular arc surfaces, and the circular arc radii of the second profile surface 331 and the third profile surface 332 are equal (wherein the circular arc radius of the second profile surface 331 corresponds to Rm1 in the appended Figure 2 , and the circular arc radius of the third profile surface 332 corresponds to Rm2 in the appended Figure 2 ); the center of the circular arc surface of the second profile surface 331 is defined as O1, and the center of the circular arc surface of the third profile surface 332 is defined as O2, O1 and O2 do not coincide with each other and are on the same radial line, wherein the distance between O1 and O2 is the radial distance between the second profile surface 331 and the third profile surface 332, i.e. the thickness of the permanent magnet 330. In this way, the "second profile surface 331" and the "third profile surface 332" of the permanent magnet 330 are set as circular arc surfaces with the same radius, but the centers O1 and O2 of the two do not coincide, but are on the same radial line, and the distance between O1 and O2 is exactly equal to the radial thickness of the permanent magnet 330. This design not only ensures that the permanent magnet 330 still maintains the ideal circular arc shape, so that the magnetic field modulation effect of the non-uniform air gap can be fully realized, but also directly defines the magnet thickness through a simple eccentricity, which is convenient for the processing and detection of the permanent magnet 330.

[0053] In an embodiment, the rotor core 310 has a plurality of concave installation grooves 311 equidistantly distributed along the circumference thereof, and the installation grooves 311 correspond one-to-one to the permanent magnets 330; the third profile surface of the permanent magnet 330 closely adheres to the bottom of the installation groove 311, i.e. the permanent magnet 330 is embedded in the installation groove 311.

[0054] In an embodiment, the rotor assembly 300 further comprises an outer protective layer 340, which is arranged on the outer circumferential surface of the rotor core 310 and covers the permanent magnet 330, for preventing the permanent magnet 330 from falling off due to excessive centrifugal force when rotating; wherein the outer protective layer 340 can adopt a metal ring structure or a non-metal injection integrated structure. Referring to Figure 5The outer protective layer 340 adopts a metal ring structure, for example, a thin-walled metal ring; refer to Figure 6 The outer protective layer 340 adopts a non-metal injection integrated structure, for example, an integrated covering structure formed by injection molding of fiber reinforced plastic.

[0055] In an embodiment, the rotor core 310 and the stator core 200 are made of soft magnetic material; wherein the stator core 200 is formed by sequentially stacking a plurality of silicon steel sheets. In this way, the soft magnetic material ensures that the material still has low coercivity and high magnetic permeability under high-frequency alternating magnetic field, can quickly respond to magnetic field changes and reduce hysteresis loss.

[0056] The application further discloses a game device comprising the inner rotor motor of any of the above embodiments. For the specific structure of the inner rotor motor, refer to the above embodiments. Since the game device adopts all the technical solutions of the above embodiments, it at least has all the beneficial effects brought by the technical solutions of the above embodiments, which will not be repeated here.

[0057] It should be noted that other contents of the inner rotor motor disclosed in the application are prior art, which will not be repeated here.

[0058] The above is only an optional embodiment of the application, and does not limit the patent scope of the application. Any direct / indirect application of the application in other related technical fields is included in the patent protection scope of the application.

Claims

1. An internal rotor electric machine characterized by: The inner rotor motor comprises a stator assembly and a rotor assembly coaxially arranged, the rotor assembly is sleeved in the stator assembly; Specifically, the stator assembly comprises a stator core and a stator winding; the stator core comprises a ring-shaped stator yoke and a plurality of stator teeth which are distributed equidistantly along the circumference of the inner side of the stator yoke, and a stator slot is formed between any two adjacent stator teeth; the stator winding is wound around the stator teeth and penetrates through the stator slot; The rotor assembly comprises a ring-shaped rotor core and a rotating shaft coaxially arranged in the rotor core; the outer circumferential surface of the rotor core is provided with a plurality of permanent magnets, and the plurality of permanent magnets are equidistantly distributed along the circumference of the rotor core; An air gap with uneven thickness is formed between the stator teeth and the permanent magnets; The number of the stator teeth is 12p, and the number of the permanent magnets is 14p; wherein p is a positive integer and p≥1; The width of the permanent magnet is defined as Mag, wherein Mag satisfies 0.5*(LCM(14p, 12p) / 360)*Dso≤Mag≤2*(LCM(14p, 12p) / 360)*Dso; wherein Dso is the diameter of the arc segment of the stator tooth, LCM(14p, 12p) is the least common multiple of the pole and slot, Dso, Mag are in units of mm, and LCM(14p, 12p) is unitless; The slot opening width of the stator slot is defined as Wsl, wherein Wsl satisfies 3*sin(Dso / LCM(14p, 12p))≤Wsl≤15*sin(Dso / LCM(14p, 12p)); wherein Dso is the diameter of the arc segment of the stator tooth, LCM(14p, 12p) is the least common multiple of the pole and slot, Dso, Wsl are in units of mm, and LCM(14p, 12p) is unitless.

2. The internal rotor electric machine of claim 1, wherein: The first profile surface of the stator tooth facing the permanent magnet comprises a first line segment, an arc segment and a second line segment connected in sequence, wherein the first line segment and the second line segment are symmetrically arranged at both ends of the arc segment; the distance between the arc segment and the second profile surface of the permanent magnet facing the stator tooth is kept equal and is defined as the first air gap; the distance between the first line segment or the second line segment and the second profile surface is defined as the second air gap, and the first air gap is smaller than the second air gap.

3. The internal rotor electric machine of claim 2, wherein: The circular arc angle of the arc segment is defined as An, wherein An satisfies 0<An<2π / (14p), and An is in units of radians.

4. The internal rotor electric machine of claim 2, wherein: The distance of the first air gap is defined as δmin, and δmin satisfies 0.1≤δmin≤8*LCM(14p, 12p) / 360; wherein LCM(14p, 12p) is the least common multiple of the pole and slot, and δmin is in units of mm.

5. The internal rotor electric machine of claim 2, wherein: The side of the permanent magnet adhering to the rotor core is defined as a third profile surface, the second profile surface and the third profile surface are both circular arc surfaces, and the circular arc radii of the second profile surface and the third profile surface are equal; a center of a circle corresponding to the circular arc surface of the second profile surface is defined as O1, and a center of a circle corresponding to the circular arc surface of the third profile surface is defined as O2, O1 and O2 do not coincide with each other and are on the same radial line, wherein the distance between O1 and O2 is the radial distance between the second profile surface and the third profile surface, that is, the thickness of the permanent magnet.

6. The internal rotor electric machine of claim 5, wherein: The rotor core is equidistantly distributed with a plurality of concave installation grooves along the circumference, the installation grooves correspond to the permanent magnets one by one; the third profile surface of the permanent magnet closely adheres to the bottom of the installation groove; And / or, the rotor assembly further comprises an outer protective layer, the outer protective layer is arranged on the outer circumferential surface of the rotor core, and the outer protective layer covers the permanent magnet; wherein the outer protective layer can adopt a metal ring structure or a non-metal injection integrated structure.

7. An internal rotor electric machine as claimed in any one of claims 1 to 6, characterized in that: The rotor core and the stator core are soft magnetic materials; the stator core is formed by a plurality of silicon steel sheets stacked in sequence.

8. A gaming device, characterized by The game device comprises the inner rotor motor of any one of claims 1 to 7.

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