Motor and manufacturing method thereof

Abstract

The invention discloses a motor and a manufacturing method thereof, and relates to the field of motors, the motor comprises a casing, a stator punching sheet and a stator yoke part, and the casing is internally provided with an accommodating cavity; the stator punching sheet comprises a plurality of stator shoe parts and stator tooth parts which are circumferentially arranged in a surrounding manner, and two adjacent stator tooth parts are connected through the stator shoe parts; the stator yoke part is annular, the outer diameter of the stator yoke part is in interference fit with the interior of the accommodating cavity, and the stator tooth part is in interference fit with the inner diameter of the stator yoke part; the material of the stator yoke part is different from the materials of the casing and the stator punching sheet, and the inner diameter of the stator yoke part is formed through machining. The stator yoke part is formed by machining steel or alloy materials with good magnetic conductivity, and the stator tooth part is formed by punching materials such as silicon steel sheets. Therefore, when the stator tooth part is in interference fit with the stator yoke part, the friction force is obviously reduced, the deformation of the stator shoe part can be reduced, and the cogging torque and the counter potential waveform distortion rate are further ensured to be within a reasonable range.

Description

Technical Field

[0001] The present invention relates to the field of motors, and in particular, to a motor and a manufacturing method thereof. Background Art

[0002] Compared with the traditional segmented spliced stator, the stator structure with separated teeth and yoke has a higher slot fill factor and a smaller cogging torque. The separation of teeth and yoke is achieved by stamping the stator teeth and the stator yoke respectively, and then pressing the stator teeth and the stator yoke together through tooling equipment. To ensure the connection reliability between the stator teeth and the stator yoke, they are connected by an interference fit. To reduce magnetic leakage and cogging torque, the connection position of the stator shoe part of the stator teeth is designed to be relatively narrow, generally about 0.3 mm, limited by the stamping process. During the pressing process, the inter-sheet friction force between the silicon steel sheets of the stator teeth and the stator yoke gradually increases with the increase of the pressing depth, which will cause the stator teeth to warp. The connection part of the stator shoe is relatively thin, which will drive the deformation of the stator inner diameter, resulting in a deviation between the air gap shape and the design value, an increase in the cogging torque, and an increase in the distortion rate of the back electromotive force waveform. Summary of the Invention

[0003] The present invention aims to solve at least one of the technical problems existing in the prior art. For this purpose, the present invention provides a motor that can reduce the friction force between the stator teeth and the stator yoke during the pressing process.

[0004] The present invention also provides a manufacturing method for manufacturing the above-mentioned motor.

[0005] The motor according to the first aspect embodiment of the present invention includes a housing, stator laminations, and a stator yoke part. An accommodation cavity is provided inside the housing; the stator laminations are axially stacked, and each stator lamination includes a plurality of stator shoe parts and stator tooth parts circumferentially arranged around. Adjacent two stator tooth parts are connected by the stator shoe parts; the stator yoke part is arranged in a ring shape, the outer diameter of the stator yoke part is connected to the accommodation cavity by an interference fit, and the stator tooth parts are connected to the inner diameter of the stator yoke part by an interference fit; the material of the stator yoke part is different from the materials of the housing and the stator laminations. The inner diameter of the stator yoke part is formed by machining. After the stator yoke part is formed separately, it is installed into the housing, or the stator yoke part and the housing are integrally cast and then formed by machining.

[0006] The motor according to the embodiment of the present invention has at least the following beneficial effects: By adopting a combination of different materials, the stator yoke part is formed by machining with a steel or alloy material with good magnetic conductivity, and the stator tooth parts are processed by stamping with materials such as silicon steel sheets. When the stator tooth parts are assembled to the stator yoke part by an interference fit, the friction force is significantly reduced, which can reduce the deformation of the stator shoe part, and further ensure that the cogging torque and the distortion rate of the back electromotive force waveform are within a reasonable range.

[0007] According to some embodiments of the present invention, the stator yoke is composed of a plurality of the segments, the plurality of segments are arranged along the axial direction of the stator yoke, and an insulating layer is provided between two adjacent segments. Along the axial direction of the stator yoke, the width of the segment is greater than the thickness of the stator punching sheet.

[0008] According to some embodiments of the present invention, the stator yoke is composed of a plurality of the segments, and the plurality of segments are arranged along the circumferential direction of the stator yoke.

[0009] According to some embodiments of the present invention, the stator yoke is composed of one segment, and the stator yoke is provided with a plurality of annular dividing grooves. The annular dividing grooves are located on the inner wall of the stator yoke. Each annular dividing groove divides the inner wall surface of the stator yoke into two contact surfaces distributed at intervals. The contact surfaces are in interference connection with the stator tooth portions, and along the axial direction of the stator yoke, the width of the contact surface is greater than the thickness of the punching sheet.

[0010] According to some embodiments of the present invention, the inner wall surface of the stator yoke is provided with a plurality of recesses, and the plurality of recesses are distributed at intervals along the circumferential direction of the stator yoke. The positions of the recesses correspond to the positions of the stator tooth portions one by one.

[0011] According to some embodiments of the present invention, the recesses are formed by cutting.

[0012] According to some embodiments of the present invention, the inner wall of the accommodating cavity is provided with a limiting portion, and the limiting portion positions the stator yoke along the axial direction of the accommodating cavity.

[0013] According to some embodiments of the present invention, the machine shell includes a housing and a machine base, the housing and the machine base are detachably connected, and the accommodating cavity is arranged in the housing.

[0014] According to some embodiments of the present invention, the power of the motor is less than or equal to 750W, and the frequency of the motor is 20Hz to 200Hz.

[0015] A manufacturing method of an electric machine according to an embodiment of the second aspect of the present invention, the electric machine includes a housing, a stator punching sheet, and a stator yoke. An accommodation cavity is provided inside the housing; a plurality of the stator punching sheets are axially stacked. The stator punching sheet includes a plurality of stator shoe portions and stator tooth portions circumferentially arranged. Two adjacent stator tooth portions are connected by the stator shoe portion; the stator yoke is arranged in a ring shape, and the outer diameter of the stator yoke is interference-fitted in the accommodation cavity, and the stator tooth portion is interference-fitted in the inner diameter of the stator yoke; the material of the stator yoke is different from the materials of the housing and the stator punching sheet. The inner diameter of the stator yoke is formed by machining. After the stator yoke is separately formed, it is installed in the housing, or the stator yoke and the housing are integrally cast and then formed by machining. The manufacturing method includes: heating the stator yoke; sleeving the stator yoke on the stator punching sheet.

[0016] The manufacturing method of the stator according to the embodiment of the present invention has at least the following beneficial effects: heating the stator yoke and thermally sleeving and assembling the stator punching sheet and the stator yoke can solve the problem of inner circle deformation during the stator assembly process and reduce the mold opening cost of the stamping die. And it can also reduce the friction force for installing the stator tooth portion, reduce the deformation of the stator shoe portion, and further ensure that the cogging torque and the distortion rate of the back electromotive force waveform are within a reasonable range.

[0017] According to some embodiments of the present invention, the stator yoke is separately formed. The manufacturing method includes: heating the housing; pressing the stator yoke and the stator punching sheet into the housing.

[0018] Additional aspects and advantages of the present invention will be given in part in the following description, become apparent in part from the following description, or be learned through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The following further describes the present invention in conjunction with the drawings and embodiments, where:

[0020] Figure 1 is a schematic diagram of a tooth-yoke separation structure in the related art;

[0021] Figure 2 is an exploded view of the electric machine according to the embodiment of the present invention;

[0022] Figure 3 is Figure 2 a schematic diagram of the stator yoke of the stator shown;

[0023] Figure 4 is Figure 3 an enlarged view of the part A shown;

[0024] Figure 5 is Figure 2Schematic diagram of the stator teeth of the stator shown;

[0025] Figure 6 is Figure 2 Schematic diagram of the assembly of the stator shown;

[0026] Figure 7 is Figure 2 Schematic diagram of the motor shown;

[0027] Figure 8 Schematic diagram of the stator yoke and the housing according to another embodiment of the present invention;

[0028] Figure 9 Schematic diagram of the stator yoke and the housing according to another embodiment of the present invention;

[0029] Figure 10 Schematic diagram of the stator yoke and the housing according to another embodiment of the present invention;

[0030] Figure 11 Schematic diagram of the stator yoke and the housing according to another embodiment of the present invention;

[0031] Figure 12 Schematic diagram of the stator yoke according to another embodiment of the present invention;

[0032] Figure 13 Schematic diagram of the stator yoke according to another embodiment of the present invention;

[0033] Figure 14 Back electromotive force comparison diagram of the stator yoke with different structures and materials;

[0034] Figure 15 Output electromagnetic torque comparison diagram of the stator yoke with different structures and materials;

[0035] Figure 16 Manufacturing process flow chart of an embodiment of the motor of the present invention;

[0036] Figure 17 Manufacturing process flow chart of another embodiment of the motor of the present invention.

[0037] Reference numerals:

[0038] 101, stator yoke; 102, stator teeth;

[0039] 201, stator punching; 202, stator yoke part; 203, block; 204, mounting hole; 205, housing; 206, accommodating cavity; 207, recess; 208, protrusion;

[0040] 501, stator shoe part; 502, stator tooth part;

[0041] 1001, housing;

[0042] 1101, Gap;

[0043] 1201, Annular dividing groove; 1202, Contact surface. Specific embodiments

[0044] The embodiments of the present invention will be described in detail below. The examples of the embodiments are shown in the accompanying drawings, where the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention and should not be construed as a limitation of the present invention.

[0045] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by terms such as up, down, front, back, left, right, etc. is based on the orientation or positional relationship shown in the accompanying drawings. This is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply 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 of the present invention.

[0046] In the description of the present invention, the meaning of "a number of" is one or more, the meaning of "a plurality of" is two or more, and understandings such as "greater than", "less than", "exceeding", etc. do not include the recited number, and understandings such as "above", "below", "within", etc. include the recited number. If there is a description of "first" and "second", it is only for the purpose of distinguishing technical features and should not be construed as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features or implicitly indicating the sequence of the indicated technical features.

[0047] In the description of the present invention, unless otherwise clearly defined, terms such as "set", "installed", "connected", etc. should be understood in a broad sense, and those skilled in the art can reasonably determine the specific meanings of the above terms in the present invention in combination with the specific content of the technical solution.

[0048] In the related art, the stator core in a motor is usually prepared by integrally blanking silicon steel sheets, that is, the stator structure is generally a combined structure of teeth and yoke. This structure is to separately manufacture multiple stator punchings and then assemble them together by splicing to meet the technical requirements of the motor. During the manufacturing process, multiple stator punchings are usually fixed together by welding, clip riveting, dot riveting, etc. In another structural form, the stator core is assembled by segmented cores, that is, the stator core includes multiple circumferentially cooperating segmented cores. Each segmented core is composed of a stator tooth, a stator yoke, and a pole shoe. The gap between two adjacent segmented cores forms a stator slot, and the stator coil is wound around the stator teeth through the stator slot. The segmented stator core has the advantages of high material utilization rate and material saving during manufacturing. However, due to the small slot size between the stator teeth after assembly, the segmented stator core can only wind the wire separately in a way of winding outside a single segmented core, and then splice the single segmented cores. And such stator winding is troublesome, with a low slot fill factor, a long end part, resulting in a low power density and a large magnetic leakage in the stator tooth part.

[0049] With the pursuit of high power density and high positioning accuracy of servo motors, many products begin to consider the stator structure with separated teeth and yoke, so that the product has a higher slot fill factor and a smaller cogging torque. The stator structure with separated teeth and yoke has a higher slot fill factor, mainly because this structure can reduce the size of the tooth slots and increase the depth of the tooth slots, thereby improving the slot fill factor. In addition, this structure can also reduce the magnetic leakage phenomenon, improve the efficiency and working stability of the motor. The cogging torque is the torque generated by the interaction between the permanent magnet and the iron core on the non-same side when the winding of the permanent magnet motor is not energized, and is caused by the tangential component of the interaction force between the permanent magnet and the armature teeth. The cogging torque will cause the motor to vibrate and generate noise, resulting in speed fluctuations, making the motor unable to run smoothly and affecting the performance of the motor.

[0050] Referring to Figure 1 As shown, the stator is composed of a stator yoke 101 and stator teeth 102, and the two are connected by a certain method. In the stator structure with separated teeth and yoke, the stator yoke 101 is usually in a circular ring shape and is used to support and fix the stator teeth 102. The stator teeth 102 have multiple protruding teeth and are used to interact with the rotor of the motor to generate electromagnetic torque. The stator structure with separated teeth and yoke has a smaller cogging torque, mainly because this structure can reduce the size of the tooth slots, thereby reducing the cogging torque. In addition, this structure can also improve the air-gap magnetic field distribution, reduce the magnetic resistance, and further reduce the cogging torque. Specifically, the stator structure with separated teeth and yoke can make the permanent magnet closer to the air gap, thereby reducing the magnetic resistance and the cogging torque. At the same time, this structure can also reduce the volume of the permanent magnet, reduce the cost, and improve the efficiency and working stability of the motor.

[0051] Compared with the traditional split stator structure, the stator structure with separated teeth and yoke has other advantages. First, since the stator yoke 101 and the stator teeth 102 are separated, they can be processed and manufactured separately, thus reducing the manufacturing difficulty and cost, and effectively solving the problems of complex assembly process and difficult to guarantee the roundness of the whole circle in the traditional split stator structure. Second, this structure can effectively improve the magnetic circuit performance of the motor, thereby improving the efficiency and performance of the motor. In addition, since the stator teeth 102 in the stator structure with separated teeth and yoke can be designed and adjusted more flexibly, it can better meet the requirements of different motors.

[0052] Referring to Figure 1 As shown, in the teeth-yoke separation structure in the related art, both the stator yoke 101 and the stator teeth 102 are formed by punching and laminating multiple cold-rolled silicon steel sheets, and then the stator teeth 102 and the stator yoke 101 are press-fitted through tooling equipment. To reduce magnetic leakage and cogging torque, the connection position of the stator shoe part 501 of the stator teeth 102 is designed to be relatively narrow. Limited by the stamping process, the dimension of the connection position of the stator shoe part 501 is generally about 0.3 mm. During the pressing process, the inter-sheet friction force between the silicon steel sheets of the stator teeth 102 and the stator yoke 101 gradually increases with the increase of the pressing depth, which will cause the stator teeth 102 to warp. The connection part of the stator shoe of the stator teeth 102 is relatively thin, resulting in the deformation of the inner diameter of the stator, so that the air gap shape deviates from the design value, the cogging torque becomes larger, and the distortion rate of the back electromotive force waveform increases. In the actual production process, some manufacturers will use the drum-shaped stamping method for the stator yoke 101 and the stator teeth 102 to solve the problem of warping of the stator teeth 102 during the assembly process, which will inevitably use more complex stamping dies and generate higher production costs.

[0053] Referring to Figure 2 As shown, it can be understood that the stator of the first aspect embodiment of the present invention includes a stator punching sheet 201 and a stator yoke part 202, and the stator punching sheet 201 and the stator yoke part 202 can be separated from each other. By setting the stator yoke part 202 and the stator punching sheet 201 as a separable assembly structure, the assembly of the stator yoke part 202 and the stator punching sheet 201 can be carried out after the stator winding is wound. On the one hand, it can simplify the winding process of the stator winding and improve the convenience of stator winding. On the other hand, it is also beneficial to improve the filling rate of the winding slot, thereby improving the performance of the motor formed by the stator core.

[0054] Referring to Figure 2As shown, it can be understood that the stator yoke 202 is composed of a single piece 203, that is, the stator yoke 202 is manufactured by integral molding from a complete piece of material, which is different from the related art where it is formed by punching and laminating multiple cold-rolled silicon steel sheets. The material of the stator yoke 202 is different from that of the stator laminations 201. The material of the stator yoke 202 is more suitable for machining and has good magnetic conductivity. For example, the material of the stator yoke 202 can be steel or alloy material. The stator yoke 202 is integrally annular, that is, the stator yoke 202 is provided with a mounting hole 204. The stator laminations 201 are located within the mounting hole 204 and are in interference fit with the stator yoke 202. The inner wall surface of the mounting hole 204 of the stator yoke 202 is a complete curved surface. According to the processing requirements of the stator yoke 202, the inner wall surface of the mounting hole 204 is a relatively smooth curved surface. During the process of interference-fitting the stator laminations 201 into the mounting hole 204, the resistance encountered is small, making the assembly process smoother. Moreover, by using the stator yoke 202 of the embodiment of the present invention, compared with Figure 1 the stator yoke 101 formed by punching and laminating multiple cold-rolled silicon steel sheets as shown, the resistance encountered by the stator laminations 201 during the assembly process is reduced, thereby reducing the deformation amount of the stator laminations 201, ensuring the installation accuracy, and reducing the influence of the installation process on the cogging torque and the distortion rate of the back electromotive force waveform.

[0055] Referring to Figure 2 As shown, it can be understood that multiple stator laminations 201 are stacked axially, and each stator lamination 201 is designed as an integral structure. Referring to Figure 5 As shown, the stator lamination 201 is integrally circular-ring-shaped. The stator lamination 201 includes a plurality of stator shoes 501 and stator teeth 502 circumferentially arranged. Two adjacent stator teeth 502 are connected by the stator shoes 501, that is, all the stator teeth 502 are spaced apart on the outer wall of the stator shoes 501. A stator slot is formed between two adjacent stator teeth 502 and the stator shoes 501. Exemplarily, there are 12 stator teeth 502 in the circumferential direction of the stator lamination 201. The stator teeth 502 are connected to each other by the stator shoes 501 to form a whole. The outer part of the stator lamination 201 is in interference fit with the inner wall of the mounting hole 204 of the stator yoke 202, that is, the stator teeth 502 are in interference fit with the inner diameter of the stator yoke 202. An enameled wire is nested on the stator teeth 502. The lead of the enameled wire is welded to the circuit board at the end of the motor. By internally routing the wires in the circuit board to connect the enameled wires on each stator tooth 502, the enameled wire is wound around the stator teeth 502, and then the lead is welded to the circuit board. During the winding process, the enameled wire can also be pressed, thereby improving the slot fill factor.

[0056] The laminated iron core can reduce the "eddy current loss". The reason for the formation of eddy current loss is the energy loss caused by the induced current in the conductor when the conductor moves in a non-uniform magnetic field or is in a magnetic field that changes with time. The closed current lines formed inside the conductor are called eddy currents. When the motor is working, there is an alternating current in the coil, and the magnetic flux generated by it is also alternating. This changing magnetic flux generates an induced current in the iron core. The induced current generated in the iron core circulates in a plane perpendicular to the direction of the magnetic flux, so it is called an eddy current. Eddy current loss will generate heat and reduce the efficiency of electronic devices, especially in high-frequency circuits. Excessive eddy current loss may cause the temperature of the components to rise, which may further cause damage to the components. In addition, excessive eddy current loss may also affect the stability of the system. For example, in a motor, eddy current loss may cause problems such as reduced motor efficiency, increased temperature rise, noise, and vibration. In one of the embodiments, the stator punch 201 is made of silicon steel sheet, so that the eddy current is in a long and narrow loop, passing through a smaller cross-section to increase the resistance in the eddy current path; at the same time, the silicon in the silicon steel increases the resistivity of the material, which also plays a role in reducing the eddy current. In contrast, the resistivity of the integral stator punch 201 is relatively low, and eddy currents are easily generated, resulting in larger eddy current losses.

[0057] In summary, for the stator of the embodiment of the present invention, the stator yoke 202 is manufactured from a complete segment 203. The stator punch 201 can play a role in reducing eddy currents. The stator yoke 202 can convert the friction between the silicon steel sheets before improvement into the friction between the silicon steel sheet and the processing surface of the stator yoke 202. The reduction of the frictional force enables the deformation amount of the stator shoe portion 501 to be reduced during the process of pressing the stator punch 201 into the stator yoke 202, ensuring the installation accuracy and reducing the influence of the installation process on the cogging torque and the distortion rate of the back electromotive force waveform.

[0058] Referring to Figure 2 As shown, it can be understood that the motor of the second aspect embodiment of the present invention includes a motor housing 205 and the stator of the first aspect embodiment of the present invention. The motor housing 205 is provided with a receiving cavity 206, and the stator is disposed in the receiving cavity 206. The motor housing 205 is usually made of aluminum, cast iron or steel plate, and has good mechanical strength and heat resistance, that is, the material of the stator yoke 202 is different from the material of the motor housing 205. The motor housing 205 not only supports the stator, but also is responsible for transferring the heat generated by the motor to the outside to maintain the stability of the motor temperature. The connection method between the stator and the motor housing 205 may vary according to the type of the motor and the design requirements. Common connection methods include interference fit, key connection, screw fixation, etc. Interference fit is a common connection method. By pressing the stator into the motor housing 205, a tight fit is achieved by using the interference amount between the two. For example, referring to Figure 6 As shown, first press the stator yoke 202 into the stator punch 201, referring to Figure 7As shown, the stator punching sheet 201 and the stator yoke 202 are pressed into the housing 205 together. The key connection is applicable to motors with larger sizes and is used to transmit torque and moment through the key. The screw fixation fixes the stator and the housing 205 together with screws, which has high stability and reliability. Compared with Figure 1 The stator yoke 101 formed by punching and laminating multiple cold-rolled silicon steel sheets as shown, the gap between two silicon steel sheets does not contact the housing 205. The stator yoke 202 in the embodiment of the present invention reduces the gap between two silicon steel sheets, so that the contact with the housing 205 is more sufficient, which is more conducive to heat dissipation. At the same time, compared with the stamping parts, the stator yoke 202 in the embodiment of the invention can also reduce the motor vibration by increasing the thickness.

[0059] Referring to Figures 2 to 4 As shown, it can be understood that the stator yoke 202 is provided with a plurality of recesses 207, and the plurality of recesses 207 are arranged on the inner wall surface of the mounting hole 204, so as to form a concave-convex structure on the inner wall surface of the mounting hole 204. The plurality of recesses 207 are distributed at intervals along the circumferential direction of the mounting hole 204. In other words, the inner wall surface of the mounting hole 204 is provided with a plurality of recesses 207 and a plurality of protrusions 208, the recesses 207 and the protrusions 208 are arranged at intervals, each protrusion 208 is located between two adjacent recesses 207, and the positions of the recesses 207 correspond to the stator tooth parts 502 one by one. While the recesses 207 cooperate with the stator punching sheet 201, as much space as possible is provided for placing the enameled wire. The recess 207 is set as a U-shaped structure, and the end part of the stator tooth part 502 is accommodated in the recess 207. The recess 207 can position the stator tooth part 502, and when the stator tooth part 502 has a tendency to rotate, the recess 207 can also play a role in limiting, solving the problem of relative rolling between the stator punching sheet 201 and the stator yoke 202.

[0060] It can be understood that the inner wall of the accommodating cavity 206 is provided with a limiting part. When the stator yoke 202 is installed in the accommodating cavity 206, since the limiting part protrudes from the inner wall of the accommodating cavity 206, after the stator yoke 202 contacts the limiting part, it cannot continue to move axially along the accommodating cavity 206. In other words, the limiting part positions the stator yoke 202 along the axial direction of the accommodating cavity 206, so as to control the assembly depth of the stator.

[0061] Referring to Figure 8Schematic diagram of the stator yoke 202 and the housing 205 shown. It can be understood that in another embodiment, the stator yoke 202 and the housing 205 are integrally cast. Through integral casting, the stator yoke 202 and the housing 205 form a whole without a connecting part, thus ensuring the structural integrity and stability. Integral casting avoids the connection and assembly process between the stator yoke 202 and the housing 205, simplifies the manufacturing process, and reduces the manufacturing cost. Since the stator yoke 202 and the housing 205 are a whole without a connecting gap 1101, their mechanical strength is improved, and they can better withstand external loads and internal pressures. The housing 205 is an important channel for motor heat dissipation. The integrally cast stator yoke 202 and housing 205 can work better together, improve the heat dissipation efficiency, and help the motor operate stably under high-load conditions. Since the stator yoke 202 and the housing 205 have no connecting part, the possibility of failures caused by loose or insecure connections is reduced, improving the reliability and stability of the motor. In summary, integrally casting the stator yoke 202 and the housing 205 can bring benefits such as structural integrity, simplified manufacturing process, enhanced mechanical strength, improved heat dissipation efficiency, and reduced possibility of failures. The multiple recesses 207 and multiple protrusions 208 provided on the stator yoke 202 can be obtained by machining methods such as broaching or boring.

[0062] Referring to Figure 9 the schematic diagram of the stator yoke 202 and the housing 205 shown. It can be understood that in another embodiment, the multiple recesses 207 and multiple protrusions 208 provided on the stator yoke 202 are cancelled. At this time, when assembling the motor, the stator lamination 201 is pressed into the mounting hole 204 of the stator yoke 202, and the stator lamination 201 and the stator yoke 202 are connected by interference fit to fix the stator lamination 201.

[0063] Referring to Figure 10 shown, it can be understood that in another embodiment, the housing 205 is a split structure, that is, the housing 205 includes a housing body 1001 and a machine base, the housing body 1001 and the machine base are detachably connected, and the accommodation cavity 206 is provided in the housing body 1001. When assembling the motor, first press the stator yoke 202 into the stator lamination 201, then press the stator lamination 201 and the stator yoke 202 together into the housing body 1001, and finally connect the machine base to the housing body 1001. When the stator needs to be repaired, the machine base can be removed, and then the stator lamination 201 and the stator yoke 202 can be removed. Compared with the integral housing 205, the split housing 205 is more convenient for repair.

[0064] At the same time, due to the adoption of the stator yoke 202 of the embodiment of the present invention, compared with Figure 1The stator yoke 101 formed by stamping and laminating multiple cold-rolled silicon steel sheets as shown will increase the eddy current loss in the stator yoke part 202. To reduce the impact of eddy current loss on the motor, the following improvement solutions are adopted in the embodiments of the present invention.

[0065] Referring to Figure 11 As shown, it can be understood that in another embodiment, the stator yoke part 202 is composed of multiple independent blocks 203. Along the axial direction of the mounting hole 204, the thickness of each block 203 is greater than the thickness of each stator punching sheet 201. Thus, when the stator punching sheet 201 moves in the mounting hole 204, the stator punching sheet 201 mainly moves along the processing surface of the block 203, and the number of gaps 1101 between two blocks 203 is small, so that the resistance received by the stator punching sheet 201 during the assembly process is reduced, and then the deformation amount of the stator punching sheet 201 is reduced, ensuring the installation accuracy and reducing the influence of the installation process on the cogging torque and the distortion rate of the back electromotive force waveform. And after the stator yoke part 202 is installed in the accommodating cavity 206, multiple blocks 203 are arranged at intervals along the axial direction of the accommodating cavity 206, and an insulating layer is provided between two adjacent blocks 203. The main function of the insulating layer is to prevent current from directly flowing through the block 203 and improve the magnetic permeability of the block 203. Since the resistivity of the insulating layer is very large and the relative current density is small, when the insulating layer separates the blocks 203 in the middle, it forces the current to flow along the surface periphery of the block 203. Since the amount of current loss is reduced, the core loss is reduced and the noise will become smaller. In addition, the insulating layer can also protect the surface of the block 203 from the influence of electric arcs and electric sparks, thereby improving its service life.

[0066] Referring to Figure 12As shown, it can be understood that in another embodiment, the stator yoke 202 is composed of a complete block 203. The block 203 is provided with a plurality of annular dividing grooves 1201. The annular dividing grooves 1201 are located on the inner wall of the mounting hole 204, and the annular dividing grooves 1201 are arranged in a circumferential direction around the mounting hole 204 for one week. Each annular dividing groove 1201 divides the inner wall surface of the mounting hole 204 into two contact surfaces 1202 distributed at intervals. Along the axial direction of the mounting hole 204, the width of the contact surface 1202 is greater than the thickness of the stator punching 201. During the process of assembling the stator punching 201 into the mounting hole 204, the contact surface 1202 is in interference connection with the stator punching 201. When the stator punching 201 moves in the mounting hole 204, the stator punching 201 mainly moves along the contact surface 1202 of the block 203. The width of the contact surface 1202 is relatively large, so that the resistance received by the stator punching 201 during the assembly process is reduced, and further the deformation amount of the stator punching 201 is reduced, ensuring the installation accuracy and reducing the influence of the installation process on the cogging torque and the distortion rate of the back electromotive force waveform. In addition, the annular dividing groove 1201 can also be filled with an insulating material, and the exposed side surface of the insulating material is located in the same curved surface as the contact surface 1202, so that the insulation material and the contact surface 1202 are overly smooth, which can reduce the assembly resistance of the stator punching 201 and can also reduce the eddy current loss through the isolation effect of the insulating material.

[0067] Referring to Figure 13 As shown, it can be understood that in another embodiment, the stator yoke 202 is composed of a plurality of independent blocks 203. The plurality of blocks 203 are arranged in the circumferential direction of the mounting hole 204. Along the axial direction of the mounting hole 204, the thickness of each block 203 is equal to the depth of the mounting hole 204, that is, the thickness of each block 203 is greater than the thickness of each stator punching 201. During the process of assembling the stator punching 201 into the mounting hole 204, the stator punching 201 is always in contact with the machining surface of the block 203. Without the frictional force of the gap 1101 between the silicon steel sheets on the stator punching 201, the assembly resistance is reduced, and further the deformation amount of the stator punching 201 is reduced, ensuring the installation accuracy and reducing the influence of the installation process on the cogging torque and the distortion rate of the back electromotive force waveform.

[0068] It can be understood that the stator yoke 202 can be processed from No. 10 steel. The reason for using No. 10 steel for the stator yoke 202 is that it can change the friction coefficient, thereby solving the problem of difficult assembly caused by friction and the problem of air gap distortion caused by the deformation of the inner diameter of the stator during the pressing process. The stator yoke 202 can also be made of materials such as No. 45 steel and amorphous alloy. In other words, the stator yoke 202 can be made of a processable material with high magnetic permeability.

[0069] Referring to Figure 14As shown, it can be understood that the dark curve represents Figure 1 the back electromotive force change trend of the stator yoke 101 formed by stamping and laminating multiple cold-rolled silicon steel sheets as shown, and the light curve represents Figure 2 the back electromotive force change trend of the stator yoke part 202 made of No. 10 steel composed of a single block 203 as shown. Through finite element calculation, the increase in stator core loss is limited. Figure 2 The scheme shown compared to Figure 1 the scheme shown, the effective value of the back electromotive force is reduced by about 6%.

[0070] Referring to Figure 15 as shown, it can be understood that the dark curve represents Figure 1 the back electromotive force change trend of the stator yoke 101 formed by stamping and laminating multiple cold-rolled silicon steel sheets as shown, and the light curve represents Figure 2 the back electromotive force change trend of the stator yoke part 202 made of No. 10 steel composed of a single block 203 as shown. Through finite element calculation, the increase in stator core loss is limited. Figure 2 The scheme shown compared to Figure 1 the scheme shown, the output electromagnetic torque is reduced by about 2%.

[0071] Referring to Figure 16 as shown, it can be understood that the invention implementation also provides a manufacturing method for a stator, and this manufacturing method can be applied to the stator shown in Figures 2 to 13 including but not limited to steps S11 to S12.

[0072] S11: Heating the stator yoke part;

[0073] S12: Sleeving the stator yoke part on the stator punching sheet.

[0074] By heating the stator yoke part, its material can be softened, and the assembly stress generated during hard interference fitting can be reduced. This helps to reduce the deformation of the stator yoke part caused by the assembly stress and improve the assembly accuracy. After heating the stator yoke part, the material has better plasticity, and it is easier to form good contact and fit during interference fitting, which can effectively transmit torque and bear load. This helps to improve the connection effect between the stator punching sheet and the stator yoke part. In the heated state, the thermal expansion coefficient of the stator yoke part material will increase, making the interference amount decrease, the assembly become relatively easy, and the deformation amount of the stator shoe part also decreases accordingly. This helps to simplify the assembly process and improve production efficiency. Heating the stator yoke part and thermally sleeving and assembling the stator punching sheet and the stator yoke part can solve the problem of inner circle deformation during the stator pressing process and reduce the die opening cost of the stamping die.

[0075] It can be understood that if for Figure 1The stator yoke formed by stamping and laminating multiple cold-rolled silicon steel sheets as shown, using the manufacturing method from step S11 to step S12, it is very difficult to keep the thermal expansion deformation amounts of each silicon steel sheet consistent, which may lead to the deterioration of the mating surface between the stator yoke and the stator teeth, further increasing the frictional force during assembly and having a counterproductive effect.

[0076] Referring to Figure 17 as shown, it can be understood that the invention embodiment also provides a manufacturing method of a motor, and this manufacturing method can be applied to Figure 2 、 Figure 7 and Figure 11 the motors as shown, including but not limited to steps S13 to S14.

[0077] S13: Heating the motor housing;

[0078] S14: Pressing the stator yoke part and the stator punching sheet into the motor housing.

[0079] By heating the motor housing, its material can be softened, reducing the assembly stress generated during hard interference fitting. This helps to reduce the deformation of the motor housing caused by the assembly stress and improve the assembly accuracy. After heating the motor housing, the material has better plasticity, and it is easier to form good contact and fit during interference fitting, which can effectively transfer the heat generated by the stator. This helps to improve the heat dissipation effect of the motor. In the heated state, the thermal expansion coefficient of the motor housing material will increase, reducing the interference amount and making the assembly relatively easy. This helps to simplify the assembly process and improve production efficiency. In addition, thermally shrinking and assembling the stator punching sheet and the stator yoke part can solve the problem of inner circle deformation during the stator assembly process and reduce the die opening cost of the stamping die.

[0080] The above has described the embodiments of the present invention in detail with reference to the drawings, but the present invention is not limited to the above embodiments. Within the knowledge scope of those of ordinary skill in the art to which it pertains, various changes can also be made without departing from the gist of the present invention.

Claims

1. Motor, characterized in that, Comprising: A housing, within which there is a receiving cavity provided. Stator laminations, a plurality of which are axially stacked. The stator laminations include a plurality of stator shoe portions and stator tooth portions circumferentially arranged. Adjacent two of the stator tooth portions are connected by the stator shoe portions. A stator yoke, arranged in a ring shape. The outer diameter of the stator yoke is press-fitted into the receiving cavity, and the stator tooth portions are press-fitted into the inner diameter of the stator yoke. The material of the stator yoke is different from that of the housing and the stator laminations. The inner diameter of the stator yoke is formed by machining. The stator yoke is separately formed and then installed into the housing, or the stator yoke and the housing are integrally cast and then formed by machining.

2. The motor according to claim 1, characterized in that, The stator yoke is composed of a plurality of blocks. The plurality of blocks are axially arranged along the stator yoke, and an insulating layer is provided between adjacent two of the blocks. Along the axial direction of the stator yoke, the width of the block is greater than the thickness of the stator lamination.

3. The motor according to claim 1, characterized in that, The stator yoke is composed of a plurality of blocks. The plurality of blocks are circumferentially arranged along the stator yoke.

4. The motor according to claim 1, characterized in that, The stator yoke is composed of one block. The stator yoke is provided with a plurality of annular dividing grooves. The annular dividing grooves are located on the inner wall of the stator yoke. Each annular dividing groove divides the inner wall surface of the stator yoke into two contact surfaces distributed at intervals. The contact surfaces are press-fitted with the stator tooth portions, and along the axial direction of the stator yoke, the width of the contact surface is greater than the thickness of the lamination.

5. The motor according to claim 1, characterized in that, The inner wall surface of the stator yoke is provided with a plurality of recesses. The plurality of recesses are circumferentially spaced along the stator yoke, and the positions of the recesses correspond one by one to those of the stator tooth portions.

6. The motor according to claim 5, characterized in that The recesses are formed by cutting.

7. The motor according to claim 1, wherein, The inner wall of the receiving cavity is provided with a limiting portion, which axially positions the stator yoke along the receiving cavity.

8. The motor according to claim 1, characterized in that, The housing includes a shell and a machine base. The shell and the machine base are detachably connected, and the receiving cavity is provided in the shell.

9. The motor according to claim 1, characterized in that, The power of the motor is less than or equal to 750W, and the frequency of the motor is 20Hz to 200Hz.

10. A method for manufacturing an electric machine, characterized in that, The motor includes a housing, stator laminations and a stator yoke. There is a receiving cavity provided inside the housing; a plurality of the stator laminations are axially stacked. The stator laminations include a plurality of stator shoe portions and stator tooth portions circumferentially arranged. Adjacent two of the stator tooth portions are connected by the stator shoe portions; the stator yoke is arranged in a ring shape. The outer diameter of the stator yoke is press-fitted into the receiving cavity, and the stator tooth portions are press-fitted into the inner diameter of the stator yoke; the material of the stator yoke is different from that of the housing and the stator laminations. The inner diameter of the stator yoke is formed by machining. The stator yoke is separately formed and then installed into the housing, or the stator yoke and the housing are integrally cast and then formed by machining. The manufacturing method includes: Heating the stator yoke. Sleeving the stator yoke on the stator laminations.

11. The manufacturing method of the motor according to claim 10, characterized in that, The stator yoke is separately formed. The manufacturing method further includes: Heating the housing. Pressing the stator yoke and the stator laminations into the housing.

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