Electric machine and assembly structure thereof

Abstract

The application provides a motor and an assembling structure thereof, the motor assembling structure comprising a stator, a first end cover, a second end cover and a fastener for fixing the stator, the first end cover and the second end cover, the stator comprising a middle core, a first side core and a second side core, the inner edge of the first end cover having a first inner arc surface, the outer edge of the first side core having a first outer arc surface in interference fit with the first inner arc surface, the inner edge of the second end cover having a second inner arc surface, and the outer edge of the second side core having a second outer arc surface in clearance fit with the second inner arc surface. The motor and the assembling structure thereof provided by the application can effectively improve the coaxiality of the stator and the end cover through the positioning fit of the first side core and the first end cover and the positioning fit of the second side core and the second end cover, thereby improving the coaxiality of the stator and the rotor and reducing the air gap between the rotor and the stator.

Description

[0001] This application is a divisional application of the patent application No. 201911025229.X for "Electric Machine and Assembly Structure Thereof" filed on October 25, 2019. TECHNICAL FIELD

[0002] The application belongs to the technical field of electric machines, and more particularly relates to an electric machine and an assembly structure thereof. BACKGROUND

[0003] In the field of electric machines, single asynchronous electric machines and other types of electric machines generally adopt an assembly mode of gap fit between a stator, a front end cover and a rear end cover for consideration of manufacturing cost. This assembly mode results in low coaxiality of the stator, the end cover and the rotor. In this assembly mode, the air gap between the rotor and the stator is large, the silicon steel and the enameled wire of the stator and the rotor are in large quantity, the utilization rate of the material is low, and a larger volume of electromagnetic material needs to be used to achieve the output power, resulting in high electromagnetic cost. SUMMARY

[0004] The application aims to provide an electric machine assembly structure to solve the technical problems of low coaxiality of the stator and the rotor and long air gap between the stator and the rotor in the prior art.

[0005] To achieve the above-mentioned purpose, the application adopts the technical scheme of providing an electric machine assembly structure, comprising a stator, a first end cover and a second end cover respectively arranged on two sides of the stator, and a fastener for fixing the stator, the first end cover and the second end cover, the stator comprising a middle core, a first side core arranged towards the first end cover and a second side core arranged towards the second end cover, the inner edge of the first end cover having a first inner circular arc surface, the outer edge of the first side core having a first outer circular arc surface in interference fit with the first inner circular arc surface, the inner edge of the second end cover having a second inner circular arc surface, and the outer edge of the second side core having a second outer circular arc surface in gap fit with the second inner circular arc surface.

[0006] Further, the thickness of the first side core is h1, the thickness of the second side core is h3, and h1 is greater than or equal to 5mm and h1 is greater than or equal to h3.

[0007] Further, the depth of the first inner circular arc surface along the axial direction thereof is L1, and L1 is greater than or equal to 5mm.

[0008] Further, the middle core is polygonally arranged, the first side core has the first outer circular arc surface, and the second side core has the second outer circular arc surface.

[0009] Further, the center of the first outer circular arc surface coincides with the center of the first side iron core, and the center of the second outer circular arc surface coincides with the center of the second side iron core.

[0010] Further, the distance between the two sides of the first side iron core is a1, and the diameter of the first outer circular arc surface is d1.

[0011] Further, the distance between the two sides of the second side iron core is a1, and the diameter of the second outer circular arc surface is d1.

[0012] Further, the distance between the two sides of the middle iron core is a2, and a1=a2.

[0013] Further, the edge of the first end cover is provided with a plurality of first mounting holes, the edge of the middle iron core is provided with a plurality of second mounting holes, and the edge of the second end cover is provided with a third mounting hole.

[0014] Further, the first end cover is provided with a first flange in contact with the surface of the middle iron core, the second end cover is provided with a second flange in contact with the surface of the middle iron core, the first mounting hole is arranged in the first flange, and the second mounting hole is arranged in the second flange.

[0015] Further, the distance between the center of the second mounting hole and the center of the middle iron core is 0.5D3, the diameter of the first outer circular arc surface is d1, and (D3-d1)≥18mm.

[0016] Further, each corner of the middle iron core is provided with a third outer circular arc surface, the center of the third outer circular arc surface coincides with the center of the middle iron core, the diameter of the third outer circular arc surface is d2, the diameter of the second mounting hole is D2, the distance between the center of the second mounting hole and the center of the middle iron core is 0.5D3, and d2-(D2+D3)≥2.2mm.

[0017] Further, each corner of the middle iron core is provided with a chamfer, the distance between the tangent lines of the two chamfers at opposite corners of the middle iron core is d2, the diameter of the second mounting hole is D2, the distance between the center of the second mounting hole and the center of the middle iron core is 0.5D3, and d2-(D2+D3)≥2.2mm.

[0018] Furthermore, the depth of the first inner arc surface along its axial direction is L1, the diameter of the first inner arc surface is D4, the diameter of the first outer arc surface is d1, the thickness of the first side core is h1, D4=d1, L1-h1≥10mm.

[0019] Furthermore, a connection between the first flange and the first inner arc surface has a rounded corner, and the radius of the rounded corner is R1, and R1≤2mm.

[0020] Furthermore, the depth of the second inner arc surface along its axial direction is L2, the diameter of the second inner arc surface is D5, the diameter of the second outer arc surface is d3, the thickness of the first side core is h1, D5=d3, L2-h3≥10mm.

[0021] Furthermore, a chamfer C is formed at a connection between the second flange and the second inner arc surface, and an axial depth of the chamfer is less than or equal to 1 mm.

[0022] Furthermore, the first end cover has a first bearing chamber on a side away from the stator, the second end cover has a second bearing chamber on a side away from the stator, and the first bearing chamber, the second bearing chamber, and the inner circumferential surface of the stator are coaxially arranged.

[0023] Furthermore, the first side core, the middle core and the second side core are all formed by stacking slices.

[0024] Furthermore, the first inner arc surface of the first end cover and the first outer arc surface of the stator are interference-fitted by a press-fit method or a temperature difference method.

[0025] The present invention also provides a motor, comprising the above-mentioned motor assembly structure, and also comprising a rotor and a first bearing and a second bearing arranged at both ends of the rotor, the first bearing being arranged in the first end cover, and the second bearing being arranged in the second end cover.

[0026] The motor and its assembly structure provided by the present invention have the following beneficial effects: compared with the prior art, the motor assembly structure of the present invention includes a stator, a first end cover, a second end cover, and fasteners for fixing the above three, and the stator includes a central iron core and a first side iron core and a second side iron core respectively arranged on both sides of the central iron core. The first side iron core has a first outer arc surface, the first end cover has a first inner arc surface, and the first inner arc surface and the first outer arc surface are interference fit; the second side iron core has a second outer arc surface, the second end cover has a second inner arc surface, and the second inner arc surface and the second outer arc surface are clearance fit; thus, through the positioning and fit of the first side iron core and the first end cover, and the positioning and fit of the second side iron core and the second end cover, the coaxiality of the stator and the end cover can be effectively improved, thereby improving the coaxiality of the stator and the rotor, and reducing the air gap between the rotor and the stator. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0028] Figure 1 A three-dimensional structural diagram of a stator provided in an embodiment of the present invention;

[0029] Figure 2 The main view of the stator provided by the embodiment of the present invention Figure 1 ;

[0030] Figure 3 The main view of the stator provided by the embodiment of the present invention Figure 2 ;

[0031] Figure 4 A left side view of a stator provided in an embodiment of the present invention;

[0032] Figure 5 A cross-sectional view of a first end cap provided in an embodiment of the present invention;

[0033] Figure 6 A cross-sectional view of a second end cap provided in an embodiment of the present invention;

[0034] Figure 7 A half-section view of a motor provided in an embodiment of the present invention.

[0035] Among them, the reference numerals in the figures are:

[0036] 1-stator; 11-first side iron core; 111-first outer arc surface; 12-second side iron core; 121-second outer arc surface; 13-middle iron core; 131-third outer arc surface; 132-second mounting hole; 13-middle iron core; 14-inner circular surface; 15-groove; 2-first end cover; 21-first inner arc surface; 22-first flange; 23-first bearing chamber; 24-first mounting hole; 3-second end cover; 31-second inner arc surface; 32-second flange; 33-second bearing chamber; 34-third mounting hole; 4-fastener; 5-rotor; 6-first bearing; 7-second bearing. DETAILED DESCRIPTION

[0037] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0038] It is to be noted that when an element is referred to as being "fixed" or "attached" to another element, it can be directly on the other element or indirectly on the other element, with one or more intervening elements. When an element is referred to as being "connected" or "coupled" to another element, it can be directly on the other element or indirectly on the other element, with one or more intervening elements.

[0039] It is to be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like, merely describe the orientation in use and / or position as shown in the drawings and are not to be construed as limiting upon the position of the device or element in use or operation, and are not intended to limit the scope of the application to a particular orientation, configuration or operation unless otherwise specifically recited in the claims.

[0040] Furthermore, the terms "first", "second", "third", "fourth", "fifth", "sixth", etc. as used herein are to be understood as descriptive for distinguishing between one element from another element, and are not to be construed as implicitly reciting a particular number of elements unless otherwise specifically recited in the claims.

[0041] Please refer to Figures 1 to 3, the motor assembly structure provided by the embodiment of the present application is described. In one of the embodiments of the motor assembly structure, the motor assembly structure comprises a stator 1, a first end cover 2, a second end cover 3 and a fastener 4, the stator 1 comprises a first side core 11, a second side core 12 and a middle core 13, and the first side core 11 and the second side core 12 are respectively arranged on the two sides of the middle core 13. The first end cover 2 is interference-fitted to the first side core 11, and the second end cover 3 is clearance-fitted to the second side core 12. More specifically, the inner edge of the first end cover 2 has a first inner arc surface 21, the outer edge of the first side core 11 has a first outer arc surface 111, the first inner arc surface 21 and the first outer arc surface 111 are interference-fitted, so that the first end cover 2 and the stator 1 are interference-fitted; the inner edge of the second end cover 3 has a second inner arc surface 31, the outer edge of the second side core 12 has a second outer arc surface 121, and the second inner arc surface 31 and the second outer arc surface 121 are clearance-fitted, so that the second end cover 3 and the stator 1 are clearance-fitted. The cooperation of the first outer arc surface 111 and the first inner arc surface 21 has a radial positioning effect on the first end cover 2, thereby improving the coaxiality of the stator 1 and the first end cover; the cooperation of the second outer arc surface 121 and the second inner arc surface 31 facilitates the assembly of the second end cover 3 and the stator. The first end cover 2 and the second end cover 3 both have bearing chambers, and the improved coaxiality of the stator 1, the first end cover 2 and the second end cover 3 improves the coaxiality of the stator 1 and the bearing, and further improves the coaxiality of the stator 1 and the rotor 5, thereby ensuring a stable output power. The cooperation of the first outer arc surface 111 and the first inner arc surface 21 and the cooperation of the second outer arc surface 121 and the second inner arc surface 31 enable the stator 1 to be embedded in the second end cover 3 and the first end cover 2 on the front and back sides respectively, thereby ensuring the coaxiality of the stator 1 and the rotor 5, reducing the air gap between the rotor 5 and the stator 1, reducing the magnetic resistance of the motor, and obtaining a higher output efficiency under the same volume of electromagnetic material, thereby improving the electromagnetic utilization rate.

[0042] The motor assembly structure in the above embodiment comprises a stator 1, a first end cover 2, a second end cover 3 and a fastener 4 for fixing the above three components, the stator 1 comprises a middle core 13 and first and second side cores 11 and 12 respectively arranged on the two sides of the middle core 13. The first side core 11 has a first outer arc surface 111, the first end cover 2 has a first inner arc surface 21, and the first inner arc surface 21 and the first outer arc surface 111 are interference-fitted; the second side core 12 has a second outer arc surface 121, the second end cover 3 has a second inner arc surface 31, and the second inner arc surface 31 and the second outer arc surface 121 are clearance-fitted; in this way, the positioning cooperation of the first side core 11 and the first end cover 2 and the positioning cooperation of the second side core 12 and the second end cover 3 can effectively improve the coaxiality of the stator 1 and the end cover, thereby improving the coaxiality of the stator 1 and the rotor 5 and reducing the air gap between the rotor 5 and the stator 1.

[0043] Please refer to Figure 4 In one of the embodiments of the stator 1, the thickness of the first side core 11 is h1, the thickness of the middle core 13 is h2, and the thickness of the second side core 12 is h3. Since the first outer arc surface 111 of the first side core 11 cooperates with the first inner arc surface 21 of the first end cover 2, and the second outer arc surface 121 of the second side core 12 cooperates with the second inner arc surface 31 of the second end cover 3, the maximum depth of the first side core 11 into the first end cover 2 is h1, and the maximum depth of the second side core 12 into the second end cover 3 is h3. If h1 and h3 are too small, the first end cover 2 may fall off from the stator 1 even if it is interference fit with the first side core 11, resulting in unstable interference fit connection between the two, and the second end cover 3 is also prone to radial shaking relative to the second side core 12, resulting in poor assembly and low assembly precision. In order to prevent the first end cover 2 from falling off, h1≥5mm; the first end cover 2 is a stretch-formed cover body, and the bending portion of the first end cover 2 is arc-shaped, which will reduce the fit thickness of the first end cover 2 and the first side core 11, while the second end cover 3 is a die-cast cover body, and the arc diameter of the bending portion thereof is small, even 90 degrees, which will not reduce the fit thickness of the second end cover 2 and the second side core 12, so h1≥h3.

[0044] Alternatively, the depth of the first inner arc surface 21 along its axial direction is L1, and L1≥5mm, so as to ensure the effective fit thickness of the first end cover 2 and the first side core 11 and enhance the reliability of the interference fit between the two.

[0045] Please refer to Figures 1 to 3 In one of the embodiments of the stator 1, the first side core 11 has a first outer arc surface 111, and the second side core 12 has a second outer arc surface 121. Alternatively, the first side core 11, the middle core 13, and the second side core 12 are polygonal, such as rectangular, and the first outer arc surface 111 is arranged at the corner portion of the first side core 11, and only the corner portion of the first side core 11 cooperates with the first end cover 3, and the second outer arc surface 121 is arranged at the corner portion of the second side core 12, and only the corner portion of the second side core 12 cooperates with the second end cover 3. The larger the above-mentioned two cooperation areas are, the greater the positioning effect of the first side core 11 on the first end cover 2 and the coaxial positioning effect of the second side core 12 on the second end cover 3 are, but the larger the above-mentioned two cooperation areas are, i.e. the larger the areas of the first outer arc surface 111 and the second outer arc surface 121 are, the smaller the material of the stator is, and the electromagnetic performance is reduced. Therefore, the size of the areas of the first outer arc surface 111 and the second outer arc surface 121 should be selected by comprehensively considering the motor performance and assembly performance.

[0046] Further, the first side core 11 and the second side core 12 are both square, the center of the first outer circular arc surface 111 coincides with the center of the first side core 11, and the center of the second outer circular arc surface 121 coincides with the center of the second side core 12. The four first outer circular arc surfaces 111 form a circumscribed circle of the first side core 11, and the center of the circumscribed circle coincides with the center of the first outer circular arc surface 111, thereby playing a role of coaxiality between the stator 1 and the first end cover 2 during assembly. The four second outer circular arc surfaces 121 form a circumscribed circle of the second side core 12, and the center of the circumscribed circle coincides with the center of the second outer circular arc surface 121, thereby playing a role of coaxiality between the stator 1 and the second end cover 3 during assembly.

[0047] Referring to Figure 3 In one embodiment of the stator 1, the center of the first outer circular arc surface 111 coincides with the center of the first side core 11, the distance between the two sides of the first side core 11 is a1, the diameter of the first outer circular arc surface 111 is d1, (a1 / cos20°)≥d1>a1, the diameter d1 corresponds to the circumscribed circle of the first side core 11, and the diameter d1 of the circumscribed circle is always greater than the side length a1, i.e., d1>a1. In Figure 3 , cosθ=(0.5a1) / (0.5d1), the smaller θ is, the smaller d1 is, the more material is cut off, the lower the electromagnetic performance is, and the worse the performance of the motor stator 1 is. Therefore, if d1 is too small, the motor performance will be affected. However, if d1 is too large, the area of the first outer circular arc surface 111 will be too small, and the fitting area of the stator 1 and the first end cover 2 cannot be guaranteed. Therefore, a1 / d1≥cos20°, and θ is maximized to 20°, so as to guarantee the fitting area of the stator 1 and the first end cover 2, thereby guaranteeing the coaxiality.

[0048] Alternatively, the first side core 11 and the second side core 12 have the same structure and size, the distance between the two sides of the second side core 12 is a1, and when the first side core 11 and the second side core 12 are both square, the side lengths of the two are equal. The diameter of the second outer circular arc surface 121 is d1, and (a1 / cos20°)≥d1>a1. Referring to Figure 6 and Figure 7 In one embodiment of the motor assembly structure, a plurality of first mounting holes 24 are formed in the edge of the first end cover 2, a plurality of second mounting holes 132 are formed in the edge of the middle core 13, a third mounting hole 34 is formed in the edge of the second end cover 3, and the fastener 4 is arranged in the first mounting hole 24, the second mounting hole 132, and the third mounting hole 34.

[0049] Optionally, when the middle iron core 13, the first side iron core 11 and the second side iron core 12 are all square, the side length of the middle iron core 13 is a2, and a1=a2, so that the side length of the middle iron core 13, the side length of the first side iron core 11 and the side length of the second side iron core 12 are all the same, thereby making the side of the stator 1 that is not cut round be a flat surface.

[0050] The middle iron core 13, the first side iron core 11 and the second side iron core 12 all have inner circular surfaces 14 for the rotor 5 to pass through, and also have slot types 15, and the structures and sizes of the inner circular surfaces 14 and the slot types 15 of the above three are all the same. The first side iron core 11, the middle iron core 13 and the second side iron core 12 can all be formed by stacking slices, each of which has an inner circular surface 14 and a slot type 15, and each inner circular surface 14 is aligned with each other, and each slot type 15 is aligned with each other. The first end cover 2 and the second end cover 3 both have bearing chambers for installing bearings for supporting the rotor 5. The bearing chamber in the first end cover 2 is a first bearing chamber 23, and the bearing chamber in the second end cover 3 is a second bearing chamber 33, and the first bearing chamber 23, the second bearing chamber 33 and the inner circular surface 14 of the stator 1 are coaxially arranged.

[0051] When assembling the first end cover 2 and the second end cover 3: first, the first end cover 2 and the first side iron core 11 are connected in interference fit, the first mounting hole 24 and the second mounting hole 132 are aligned, and the first inner circular surface 21 and the first outer circular surface 111 are attached to each other to improve the coaxiality of the first bearing chamber 23 of the first end cover 2 and the inner circular surface 14 of the stator 1, so that the first end cover 2 is fastened to the stator 1; then the second end cover 3 is connected to the second side iron core 12 at room temperature in clearance fit, the third mounting hole 34 and the second mounting hole 132 are aligned, and the second inner circular surface 31 and the second outer circular surface 121 are attached to each other to improve the coaxiality of the second bearing chamber 33 of the second end cover 3 and the inner circular surface 14 of the stator 1; the fastener 4 passes through the first mounting hole 24, the second mounting hole 132 and the third mounting hole 34 to fix the first end cover 2, the stator 1 and the second end cover 3 to each other.

[0052] Optionally, the first mounting hole 24 and the second mounting hole 132 are light holes, and the third mounting hole 34 is a threaded hole, and the fastener 4 is a threaded fastener, and the fastener 4 presses the first end cover 2, the stator 1 and the second end cover 3 to each other and is threadedly connected with the second end cover 3.

[0053] Optionally, the first end cover 2 and the first side core 11 are interference fitted by press-in method or temperature difference method. Press-in method: clean the first inner arc surface 21 and the first outer arc surface 111, align the first mounting hole 24 and the second mounting hole 132, align the first inner arc surface 21 and the first outer arc surface 111, press the first end cover 2 to the stator 1 by weight pressing or oil pressure machine, and the first side core 11 of the stator 1 is pressed into the cylindrical cavity surrounded by the first inner arc surface 21. Temperature difference method: clean the first inner arc surface 21 and the first outer arc surface 111, heat the first end cover 2 to make it expand moderately, install the first end cover 2 to the stator 1 after expansion, align the first mounting hole 24 and the second mounting hole 132, and after cooling, the first end cover 2 shrinks and is interference fitted with the stator 1. The first end cover 2 and the first side core 11 can also be interference fitted by artificial knocking method, cold mounting method, etc.

[0054] Please refer to Figure 2 and Figure 3 The number of the second mounting holes 132 is multiple, and the second mounting holes 132 are distributed circumferentially with the center of the middle core 13 as the center, so that the distances from the centers of all the second mounting holes 132 to the center of the middle core 13 are equal, which can further improve the coaxiality of the inner circular surface 14 of the stator 1 and the bearing chamber when the first mounting hole 24, the second mounting hole 132 and the third mounting hole 34 are aligned. For example, the number of the second mounting holes 132 is four, which are respectively arranged at the four corners of the middle core 13, and the second mounting holes 132 do not pass through the first side core 11 and the second side core 12, i.e. are arranged at the tangent circles of the first side core 11 and the second side core 12, so that the first end cover 2 and the second end cover 3 are directly attached to the surface of the middle core 13 and are aligned with the mounting holes.

[0055] Please refer to Figure 5 and Figure 6 In one embodiment of the motor mounting structure, the first end cover 2 is provided with a first flange 22, the first flange 22 is radially extended from the end of the first inner arc surface 21, the surface of the first flange 22 is used to tightly attach to the surface of the middle core 13, and the first mounting hole 24 is arranged in the first flange 22 to avoid deformation of the edge of the first end cover 2 when the fastener 4 is tightened. The second end cover 3 is provided with a second flange 32, the second flange 32 is radially extended from the end of the second inner arc surface 31, the surface of the second flange 32 is used to tightly attach to the other surface of the middle core 13, and the third mounting hole 34 is arranged in the second flange 32 to avoid deformation of the edge of the second end cover 3 when the fastener 4 is tightened. In this way, compared with the conventional cantilevered screws used for the end covers in front of and behind the stator 1, the stator 1 supports the end covers in front of and behind the stator 1, which effectively reduces the deformation of the outer edge of the end cover.

[0056] Please refer to Figure 2In one embodiment of the stator 1, the centers of all the second mounting holes 132 are equidistant from the center of the middle core 13. After the first end cover 2 and the second end cover 3 are installed, the distance between the first mounting holes 24 and the outer wall of the first end cover 2 cannot be too small due to the need for sufficient space for the installation of the fasteners 4. Therefore, the distance between the center of the second mounting hole 132 and the adjacent first outer arc surface 111 cannot be too small. The distance between the center of the second mounting hole 132 and the center of the middle core 13 is 0.5D3, the diameter of the first outer arc surface 111 is d1, and (D3-d1)≥18mm to ensure sufficient installation space for the fasteners 4. For example, D3-d1 is equal to 18mm, 19mm, 20mm, etc.

[0057] Referring to Figure 2 In one embodiment of the stator 1, each corner of the middle core 13 is provided with a third outer arc surface 131, and the center of the third outer arc surface 131 coincides with the center of the middle core 13, i.e., the outer periphery of the middle core 13 has an inscribed circle with a diameter of d2, and the diameter of the second mounting hole 132 is D2. The distance between the inner wall of the second mounting hole 132 and the surface of the inscribed circle of the middle core 13 cannot be too close, otherwise the strength of the inscribed circle will be too low to withstand large torsional and radial forces, and it will be easy to break under stress. To ensure the strength of the four corners of the middle core 13, d2-(D2+D3)≥2.2mm, and d2-(D2+D3) can be 2.5mm, 2.7mm, 3mm, etc.

[0058] In another embodiment of the stator 1, each corner of the middle core 13 is provided with a chamfer, and the distance between the two tangent lines of the chamfers at opposite corners of the middle core 13 is d2, and the diameter of the second mounting hole 132 is D2. Similarly, the distance between the inner wall of the second mounting hole 132 and the surface of the chamfer cannot be too close, otherwise the strength of the corners of the middle core 13 will be too low to withstand large torsional and radial forces, and it will be easy to break under stress. To ensure the strength of the four corners of the middle core 13, d2-(D2+D3)≥2.2mm, and d2-(D2+D3) can be 2.5mm, 2.7mm, 3mm, etc.

[0059] Referring to Figure 5In one embodiment of the first end cover 2, the first inner arc surface 21 has a depth L1 along its axial direction, the first inner arc surface 21 has a diameter D4, and the first outer arc surface 111 has a diameter d1. In order to match the first inner arc surface 21 and the first outer arc surface 111, D4 = d1, but the tolerance band of D4 is below that of d1. In this embodiment, the first side core 11 is completely inserted into the first end cover 2, and when the thickness h1 of the first side core 11 is constant, the smaller the difference between the depth L1 of the first inner arc surface 21 along its axial direction and h1, the smaller the distance between the first side core 11 and the heat dissipation hole on the first end cover 2. The heat dissipation hole is punched and formed, and the material around the heat dissipation hole will be deformed. If the first side core 11 is too close to the heat dissipation hole, it will affect the matching precision. Therefore, L1 - h1 ≥ 10 mm, so that the first side core 11 has a certain distance from the heat dissipation hole after installation, avoiding the deformation of the edge of the heat dissipation hole affecting the matching precision.

[0060] Please refer to Figure 5 In one embodiment of the first end cover 2, the connection between the first flange 22 and the first inner arc surface 21 has a rounded corner. Since the first inner arc surface 21 and the first outer arc surface 111 are in interference fit, the rounded corner serves as a guide for the assembly of the first end cover 2 and the stator 1, and will not be crushed and broken during assembly. The radius of the above-mentioned rounded corner is R1. If R1 is too large, the matching depth of the first inner arc surface 21 and the first outer arc surface will decrease accordingly, which may lead to a decrease in the reliability of the interference fit. Therefore, R1 ≤ 2 mm.

[0061] Please refer to Figure 6 In one embodiment of the second end cover 3, the second inner arc surface 31 has a depth L2 along its axial direction, the second inner arc surface 31 has a diameter D5, and the second outer arc surface 121 has a diameter d3. In order to match the second inner arc surface 31 and the second outer arc surface 121, D5 = d3, but the tolerance band of D5 is above that of d1. In this embodiment, the second side core 12 is completely inserted into the second end cover 3, and when the thickness h3 of the second side core 12 is constant, the smaller the difference between the depth L2 of the first inner arc surface 21 along its axial direction and h3, the smaller the space for the winding. In order to ensure the reliability of the winding installation, L2 - h3 ≥ 10 mm, so that the second side core 12 and the second inner arc surface 31 have sufficient space away from one end of the stator 1. Here, d3 can be equal to d1.

[0062] Please refer to Figure 6In one of the embodiments of the second end cover 3, the junction between the second flange 32 and the second inner circular surface 31 has a chamfer C with an axial depth less than or equal to 1 mm. Since the first inner circular surface 21 and the first outer circular surface 111 are in clearance fit, the chamfer serves as a guide for the assembly of the second end cover 3 and the stator 1, but the edge of the chamfer C is in the form of an edge, which, when the second end cover 3 is slightly misaligned with the stator 1, does not cause the second end cover 3 to slide off the stator 1 as a rounded chamfer does, and the installation of the second end cover 3 is facilitated.

[0063] Referring to Figure 7 The application further provides an electric machine, which comprises the electric machine assembly structure in any of the above embodiments, and further comprises a rotor 5 and first and second bearings 6 and 7 arranged at two ends of the rotor 5, the first and second bearings 6 and 7 being used to support the rotor 5 and enable the rotor 5 to rotate relative to the stator 1. The first bearing 6 is arranged in the first end cover 2, and the second bearing 7 is arranged in the second end cover 3. The first end cover 2 is correspondingly provided with a first bearing chamber 23, and the second end cover 3 is correspondingly provided with a second bearing chamber 33.

[0064] The electric machine provided by the above embodiments adopts the electric machine assembly structure, and through the positioning fit of the first side part core 11 and the first end cover 2 and the positioning fit of the second side part core 12 and the second end cover 3, the coaxiality of the stator 1 and the end cover can be effectively improved, thereby improving the coaxiality of the stator 1 and the rotor 5, and further shortening the overall length of the electric machine in the axial direction and reducing the air gap length between the rotor 5 and the stator 1.

[0065] Specifically, when assembling the electric machine in the above embodiments, the first bearing 6 is first arranged in the first bearing chamber 23 of the first end cover 2, then the first end cover 2 is in interference fit with the first side part core 11 of the stator 1, then the rotor 5 is arranged through the inner circular surface 14 of the stator 1 and coaxially arranged with the inner circular surface 14 of the stator 1, then the second bearing 7 is arranged in the second bearing chamber 33 of the second end cover 3, and then the second end cover 3 is assembled to the second side part core 12 of the stator 1, and the fastener 4 is arranged through the first end cover 2, the middle part core 13 and the second end cover 3, so as to fixedly connect the first end cover 2, the middle part core 13 and the second end cover 3.

[0066] The above only describes preferred embodiments of the application and is not intended to limit the application, and any modification, equivalent replacement and improvement made within the spirit and principle of the application shall be included in the protection scope of the application.

Claims

1. An electric motor assembly structure, characterized by: The stator includes a middle core, a first side core arranged towards the first end cover, and a second side core arranged towards the second end cover, the inner edge of the first end cover has a first inner arc surface, the outer edge of the first side core has a first outer arc surface matched with the first inner arc surface, the inner edge of the second end cover has a second inner arc surface, and the outer edge of the second side core has a second outer arc surface matched with the second inner arc surface, the depth of the first inner arc surface along the axial direction thereof is L1, the thickness of the first side core is h1, and L1-h1 is greater than or equal to 10 mm. The edge of the first end cover is provided with a plurality of first mounting holes, the edge of the middle core is provided with a plurality of second mounting holes, the edge of the second end cover is provided with a third mounting hole, and the fastener is arranged through the first mounting hole, the second mounting hole and the third mounting hole, and the second mounting holes are distributed in a circumferential direction with the center of the middle core as a center.

2. The motor assembly structure of claim 1, wherein: The first outer arc surface and the first inner arc surface are in interference fit.

3. The motor assembly structure of claim 1, wherein: The second outer arc surface and the second inner arc surface are in clearance fit.

4. The motor assembly structure of claim 1, wherein: The thickness of the second side core is h3, and h1 is greater than or equal to 5 mm and h1 is greater than or equal to h3.

5. The motor assembly structure of claim 4, wherein: The depth of the first inner arc surface along the axial direction thereof is greater than or equal to 5 mm.

6. The motor assembly structure of claim 1, wherein: The middle core is polygonal.

7. The motor assembly structure of claim 6, wherein: The center of the first outer arc surface coincides with the center of the first side core, and the center of the second outer arc surface coincides with the center of the second side core.

8. The motor assembly structure of claim 6, wherein: The distance between the two sides of the first side core is a1, the diameter of the first outer arc surface is d1, (a1 / cos20°) is greater than or equal to d1 and d1 is greater than or equal to a1.

9. The motor assembly structure of claim 8, wherein: The distance between the two sides of the first side core is a1, the diameter of the first outer arc surface is d1, (a1 / cos20°) is greater than or equal to d1 and d1 is greater than or equal to a1.

10. The motor assembly structure of claim 1, wherein: The first end cover is provided with a first flange in surface contact with the middle core, the second end cover is provided with a second flange in surface contact with the middle core, the first mounting hole is arranged in the first flange, and the second mounting hole is arranged in the second flange.

11. The motor assembly structure of claim 1, wherein: The diameter of the circle in which the center of the second mounting hole is located is D3, the diameter of the first outer arc surface is d1, and (D3-d1) is greater than or equal to 18 mm.

12. The motor assembly structure of claim 1, wherein: Each corner of the middle core is provided with a third outer arc surface, the center of the third outer arc surface coincides with the center of the middle core, the diameter of the third outer arc surface is d2, the diameter of the second mounting hole is D2, the diameter of the circle in which the center of the second mounting hole is located is D3, and d2-(D2+D3) is greater than or equal to 2.2 mm.

13. The motor assembly structure of claim 1, wherein: Each corner of the middle core is provided with a chamfer, the distance between the two tangent lines of the chamfers at opposite corners of the middle core is d2, the diameter of the second mounting hole is D2, the diameter of the circle in which the center of the second mounting hole is located is D3, and d2-(D2+D3) is greater than or equal to 2.2 mm.

14. The motor assembly structure of claim 10, wherein: The diameter of the first inner arc surface is equal to the diameter of the first outer arc surface.

15. The motor assembly structure of claim 14, wherein: The junction of the first flange and the first inner arc surface has a fillet with a radius R1, R1≤2mm.

16. The motor assembly structure of claim 10, wherein: The second inner arc surface has a depth along the axial direction of L2, the diameter of the second inner arc surface is equal to the diameter of the second outer arc surface, and the thickness of the second side core is h3, L2-h3≥10mm.

17. The motor assembly structure of claim 16, wherein: The junction of the second flange and the second inner arc surface has a chamfer C with an axial depth less than or equal to 1mm.

18. The motor assembly structure of any one of claims 1-17, wherein: The first inner arc surface of the first end cover and the first outer arc surface of the stator are interference fitted by press-in method or temperature difference method.

19. An electric machine characterized by: The motor assembly structure comprises a rotor and first and second bearings arranged at both ends of the rotor, the first bearing is arranged in the first end cover, and the second bearing is arranged in the second end cover.

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