STATOR AND METHOD FOR MANUFACTURING A STATOR

Abstract

The present disclosure relates to a stator comprising: a core; a coil with a coil end section projecting from an axial end section of the core; a cylindrical element in contact with the end section of the core and covering the circumference of the coil end section; and a molded resin filled into an interior space of the cylindrical element. The stator includes an elastic element arranged between the cylindrical element and the molded resin and in close contact with both.

Description

TECHNICAL AREA

[0001] The present disclosure relates to a stator and a method for manufacturing a stator. STATE OF THE ART

[0002] In general, a motor is known that comprises a stator with a coil and a movable element (rotor) rotatably mounted within the stator. To improve the insulation performance, cooling performance, and the like for the coil, a molded resin can be filled into the interior of a cylindrical element that covers one end section of the coil (for example, JP 2004-120923 A). SUMMARY OF THE INVENTION

[0003] In some cases, the cylindrical element can be machined after its interior has been filled with the molding resin. In this case, it is desirable to eliminate dimensional errors (poor dimensions) of the machined cylindrical element.

[0004] A first aspect of the present disclosure is characterized by a stator comprising: a core; a coil provided on the core and comprising a coil end section projecting axially from an end section of the core; a cylindrical element in contact with the end section of the core and covering an outer circumference of the coil end section; a molding resin with which an interior of the cylindrical element is filled; and an elastic element arranged between the cylindrical element and the molding resin, the elastic element being in close contact with the cylindrical element and the molding resin.

[0005] A second aspect of the present disclosure is characterized by a method for manufacturing a stator, the method comprising: a filling step in which molten resin is filled into an interior of a cylindrical element attached to each of the two end sections of a core in an axial direction of the core; a cooling step in which the molten resin is cooled in order to harden the molten resin;and a cutting step for cutting an outer circumferential surface of the cylindrical element until a height difference between the outer circumferential surface of the cylindrical element and an outer circumferential surface of the core becomes equal to or less than an acceptable value, wherein each of the cylindrical elements is in axial contact with the end section of the core prior to filling with the molten resin in the filling step, and covers an outer circumference of a coil end section projecting from the end section, wherein an elastic element is attached to an inner surface of each of the cylindrical elements, and the cutting in the cutting step is carried out in a state in which the elastic element attached to the inner surface of the cylindrical element is in close contact with a mold resin obtained by curing the molten resin. BRIEF DESCRIPTION OF THE DRAWINGS [ Fig. 1] Fig. Figure 1 is a cross-sectional view of a stator of a motor according to one embodiment; [ Fig. 2] Fig. 2 is a flowchart (flow diagram) that shows the sequence of a manufacturing process for the stator; [ Fig. 3] Fig. Figure 3 is a cross-sectional view showing the state after an assembly step; [ Fig. 4] Fig. Figure 4 is a view showing a cylindrical element that is assembled in the assembly step; [ Fig. 5] Fig. 5 is a cross-sectional view showing the state after a filling step; [ Fig. 6] Fig. Figure 6 is a view showing a cylindrical element according to a first modification; [ Fig. 7] Fig. Figure 7 is a view showing a cylindrical element according to a second modification; [ Fig. 8] Fig. Figure 8 is a view showing a cylindrical element according to a third modification; [ Fig. 9] Fig. Figure 9 is a cross-sectional view of a stator of a motor according to a fifth modification; and [ Fig. 10] Fig. Figure 10 is a cross-sectional view showing a state after an assembly step in the fifth modification. DETAILED DESCRIPTION OF THE INVENTION

[0006] The interior of a cylindrical element, which covers a coil end section of a coil, is filled with a molding resin. The molding resin is in a molten state when poured into the interior and in a cured state after filling. However, the molding resin can shrink as it transitions from the molten to the cured state. When the molding resin shrinks, a gap forms between the cylindrical element and the molding resin. In this case, the gap causes a dimensional error in the machined cylindrical element. The following disclosure is an embodiment for suppressing the occurrence of dimensional errors (poor dimensions) in the machined cylindrical element. [Versions] Fig. Figure 1 is a cross-sectional view of a stator 10 of a motor according to one embodiment. The stator 10 is also referred to as the stator. The stator 10 comprises a core 12, a coil 14, cylindrical elements 16, a molded resin 18, and elastic elements 20.

[0007] The core 12, for example, is formed from several magnetic steel sheets 12a stacked in the axial direction DA. The axial direction DA is the direction in which a central axis AX of the core 12 extends. The central axis AX of the core 12 coincides with the axis of rotation of the stator 10. The core 12 is also referred to as the iron core. The core 12 comprises a cylindrical core body and several teeth that project inwards from the core body in the radial direction DB of the core 12. A coil 14 is provided in each of the teeth. The coil 14 can be wound around the tooth.

[0008] The coil 14 has coil end sections 14E. The coil end sections 14E each protrude from one end section 12E1 of the core 12 and from the other end section 12E2 of the core 12. One end section 12E1 and the other end section 12E2 of the core 12 are end sections 12E of the core 12 in the axial direction DA. An electrical current line LN is connected to the coil 14.

[0009] Each of the cylindrical elements 16 is formed in a cylindrical shape. The cylindrical element 16 is made, for example, of aluminum, an iron-based material, or the like. The cylindrical element 16 is arranged axially DA at the end section 12E of the core 12. The cylindrical element 16 arranged at one end section 12E1 of the core 12 can be designated cylindrical element 16A. The cylindrical element 16 arranged at the other end section 12E2 of the core 12 can be designated cylindrical element 16B. The cylindrical element 16A and the cylindrical element 16B have essentially the same structure.

[0010] The cylindrical element 16 is in axial contact DA with the end section 12E of the core 12. The cylindrical element 16 surrounds the coil end section 14E from the outside and covers the outer circumference of the coil end section 14E.

[0011] The molding resin 18 is arranged inside the cylindrical element 16. The molding resin 18 is poured into the interior of the cylindrical element 16. After being poured, the molding resin 18 transitions from a molten state to a hardened state.

[0012] Each of the elastic elements 20 is arranged between each of the cylindrical elements 16 and the molding resin 18. In the present embodiment, the elastic element 20 has an annular shape. The elastic element 20 is arranged circumferentially around the entire circumference of the inner surface of the cylindrical element 16 at the end section of the cylindrical element 16 on the side opposite the core side 12. The elastic element 20 is preferably made of an insulating material to ensure reliable electrical insulation between the coil 14 and the cylindrical element 16.

[0013] The elastic element 20 is in close contact with each of the cylindrical elements 16 and the molding resin 18. In the present embodiment, the elastic element 20 has adhesive layers 20LY on both surfaces. The adhesive layer 20LY on one surface of the elastic element 20 is bonded to the inner surface of the cylindrical element 16, and the adhesive layer 20LY on the other surface is bonded to the molding resin 18. The elastic element 20 can be a double-sided adhesive tape or an adhesive. The adhesive layer 20LY can be an adhesive.

[0014] Therefore, even if the resin 18 shrinks radially in the direction of the cylindrical element 16 during curing from its molten state, no gap forms between the molding resin 18 and the elastic element 20. This means that the elastic element 20 expands elastically in the radial direction of the cylindrical element 16 in accordance with the shrinkage of the resin 18, so that no gap forms between the resin 18 and the cylindrical element 16. Therefore, the close contact between the cylindrical element 16 and the resin 18 is maintained.

[0015] In the present embodiment, the elastic element 20 is arranged circumferentially over the entire circumference of the cylindrical element 16. Therefore, the elastic element 20 can be held firmly in close contact with both the cylindrical element 16 and the molding resin 18.

[0016] Next, the following will be discussed using the Fig. Sections 2 to 5 describe a method for manufacturing the stator 10. The method for manufacturing the stator 10 comprises an assembly step P1, a filling step P2, a cooling step P3, and a cutting (machining) step P4 (see Fig. 2).

[0017] Assembly step P1 is a step to mount the cylindrical elements 16 onto the core 12 (see Fig. 3) In assembly step P1, the cylindrical element 16A is attached, for example, by a shrink fit to one end section 12E1 of the core 12. In this case, the cylindrical element 16A covers the outer circumference of the coil end section 14E that protrudes from one end section 12E1 of the core 12. In assembly step P1, the cylindrical element 16B is attached, for example, by a shrink fit to the other end section 12E2 of the core 12. In this case, the cylindrical element 16B covers the outer circumference of the coil end section 14E that protrudes from the other end section 12E2 of the core 12.

[0018] The elastic element 20 is connected to the inner circumferential surface of the cylindrical element 16 attached to the core 12 (see Fig. 4) The elastic element 20 can be connected before the cylindrical element 16 is attached to the core 12 or after the cylindrical element 16 has been attached to the core 12.

[0019] The filling step P2 is a step for pouring in a molten resin 22 (see Fig. 3) into the interiors of the cylindrical elements 16 attached to the core 12. The molten resin 22 is obtained by heating and liquefying the molding resin 18. Examples of such resins are thermoplastic resins. In filling step P2, the molten resin 22 is poured, for example, from the cylindrical element 16A into the interiors of the cylindrical elements 16. In this case, a space AR formed in the core 12 for arranging a rotor (not shown) and an opening 18OP of the cylindrical element 16B are sealed.

[0020] The molten plastic 22 cast from the cylindrical element 16A flows through the spaces between the teeth of the core 12 into the interior of the cylindrical element 16B and is stored there. When the interior of each of the cylindrical elements 16A and the cylindrical element 16B is filled with the molten resin 22 (see Fig. 5), the coil end sections 14E and the connecting section between the coil end section 14E and the electrical current line LN are immersed in the molten resin 22.

[0021] Cooling step P3 is a step to cool the molten resin 22 in order to harden it. In cooling step P3, the process waits until the molten resin 22 has hardened. The molten resin 22 hardens and becomes the mold resin 18. The mold resin 18 and each of the elastic elements 20 adhere to one another. Even if the mold resin 18 shrinks during curing, the elastic element 20 follows the shrinkage, thus maintaining close contact between the mold resin 18 and the cylindrical element 16. This prevents the mold resin 18 and the cylindrical element 16 from separating and prevents a gap from forming between them.

[0022] Cutting step P4 is a step for machining (cutting operation) the cylindrical elements 16. In cutting step P4, the outer circumferential surface of each of the cylindrical elements 16 is cut (machined) until a step (i.e., a height difference) ST (see Fig. 5) the difference between the outer circumferential surface of the cylindrical element 16 and the outer circumferential surface of the core 12 is equal to or less than an acceptable value. Preferably, the cutting is carried out until stage ST becomes zero. For example, a lathe is used in cutting step P4. After completion of cutting step P4, the stator 10 is obtained (see Fig. 1) In this case, the outer circumferential surface of the cylindrical element 16 and the outer circumferential surface of the core 12 are essentially flush with each other.

[0023] Even if the molding resin 18 shrinks during cooling step P3, the elastic elements 20 maintain close contact between the molding resin 18 and the cylindrical elements 16. Therefore, the cutting step on the cylindrical elements 16 can be performed stably, unlike in the case where a gap forms between the molding resin 18 and the cylindrical elements 16 due to shrinkage. This makes it possible to suppress a reduction in yield due to dimensional errors (poor dimensions) of the cylindrical elements 16.

[0024] The above embodiment can be modified as follows. In the following modifications, the description corresponding to the embodiment is omitted. In the drawings used to illustrate the following modifications, the same components as in the embodiment are designated with the same reference numerals. (Modification 1)

[0025] Fig. Figure 6 shows a cylindrical element 16 according to a first modification. In the present modification, several elastic elements 20 are attached to the inner circumferential surface of the cylindrical element 16, which is mounted on the core 12 in assembly step P1.

[0026] The multiple elastic elements 20 are arranged at intervals in the axial direction DA of the cylindrical element 16. Each of the elastic elements 20 has an annular shape. Each elastic element 20 is arranged circumferentially over the entire circumference of the inner circumferential surface of the cylindrical element 16.

[0027] In the present modification, the contact surfaces of the elastic elements 20 are enlarged with respect to both the cylindrical element 16 and the molding resin 18 compared to the embodiment. Therefore, the elastic elements 20 can be held firmly in close contact with both the cylindrical element 16 and the molding resin 18. (Modification 2)

[0028] Fig. Figure 7 is a schematic representation of a cylindrical element 16 according to a second modification. In the present modification, several elastic elements 20 are attached to the inner circumferential surface of the cylindrical element 16, which is mounted on the core 12 in assembly step P1.

[0029] The multiple elastic elements 20 are arranged at intervals in each of the axial direction DA of the cylindrical element 16 and the circumferential direction of the cylindrical element 16. Each of the elastic elements 20 has a hemispherical outer shape. The surface of each elastic element 20 that is in contact with the inner circumferential surface of the cylindrical element 16 is planar.

[0030] Therefore, in the present modification, the contact area (first contact area) of the elastic elements 20 with the cylindrical element 16 is made small, and the contact area (second contact area) of the elastic elements 20 with the molding resin 18 can be made larger than the first contact area. This improves close contact with the molding resin 18 as it cures from the molten state. Furthermore, in the present modification, it is possible to reduce the concentration of stresses that arise in the elastic elements 20 due to the shrinkage of the molding resin 18. (Modification 3)

[0031] Fig. Figure 8 is a schematic representation of a cylindrical element 16 according to a third modification. In the present modification, several elastic elements 20 are attached to the inner circumferential surface of the cylindrical element 16, which is mounted on the core 12 in assembly step P1.

[0032] The multiple elastic elements 20 are arranged at intervals around the circumference of the cylindrical element 16. Each elastic element 20 extends along the axial direction DA of the cylindrical element 16. Each elastic element 20 has multiple polygonal sections 20A, each with a polygonal outer shape. The multiple polygonal sections 20A are connected to each other along the axial direction DA of the cylindrical element 16. Compared to a case where the elastic element 20 extends directly along the axial direction DA of the cylindrical element 16 without the polygonal sections 20A, the contact area of ​​the elastic element 20 with the molding resin 18 is increased. This improves close contact with the molding resin 18 as it cures from the molten state.

[0033] Each polygonal section 20A has a through-hole TH. A through-hole TH is provided for each polygonal section 20A. That is, each polygonal section 20A has an annular shape. The contact area of ​​the elastic element 20 with the molding resin 18 is increased compared to the case where the through-hole TH is not formed in the elastic element 20. This allows for improved contact with the molding resin 18 as it hardens from the molten state. (Modification 4)

[0034] The elastic element 20 can be connected to the entire inner circumferential surface of the cylindrical element 16, which is attached to the core 12 in assembly step P1. (Modification 5)

[0035] Fig. Figure 9 shows a cross-sectional view of a stator 10 of a motor according to a fifth modification. The elastic element 20 can additionally be arranged between the cylindrical element 16 and the molding resin 18, between the coil end section 14E and the molding resin 18. The elastic element 20 is also in close contact with the coil end section 14E and the molding resin 18. This allows the cutting operation on the cylindrical element 16 to be carried out even more reliably.

[0036] In the case of the present modification, as in Fig. Figure 10 shows that in assembly step P1, the elastic elements 20 are bonded to the inner circumferential surfaces of the cylindrical elements 16 and the surfaces of the coil end sections 14E (plastic adhesive composite system). The elastic elements 20 can be connected before or after the cylindrical elements 16 are attached to the core 12.

[0037] In the present modification, it is advantageous to arrange the elastic element 20 between a portion of the surface of the coil end section 14E and the molding resin 18. This is because, if the elastic element 20 is arranged between the entire surface of the coil end section 14E and the molding resin 18, the penetration of the molten resin 22 into the coil end section 14E is slow. Fig. 9 and Fig. Figure 10 shows a case in which the elastic element 20 is arranged between the outer circumferential side of the surface of each coil end section 14E and the molding resin 18. In this case, the molten resin 22 rapidly penetrates the coil end section 14E from the inner circumferential side of the surface during filling step P2. (Modification 6)

[0038] If a liquid adhesive is used, the elastic elements 20 can be provided after cooling step P3. In this case, the elastic elements 20 are not bonded to the inner circumferential surfaces of the cylindrical elements 16 in assembly step P1. After cooling step P3 and before cutting step P4, the liquid adhesive is poured into a gap between the mold resin 18, which is formed by the curing of the molten resin 22 in cooling step P3, and each cylindrical element 16. After the adhesive has cured, cutting step P4 is performed. That is, the cutting of the cylindrical elements 16 is carried out in a state where the cylindrical elements 16 and the mold resin 18 are bonded together by the adhesive. In the case of the present modification, the adhesive can also be poured into the gaps between the surfaces of the coil end sections 14E and the mold resin 18. (Modification 7)

[0039] The above-mentioned modifications can be combined in a suitable manner, provided that no technical incompatibilities arise.

[0040] As described above, the elastic element 20, according to the embodiment described above (including the modifications), maintains close contact between the molding resin 18 and the cylindrical element 16. Furthermore, the elastic element 20 can maintain close contact between the molding resin 18 and the coil end section 14E. This helps to suppress dimensional errors (poor dimensions) of the cylindrical elements 16.

[0041] The following additional remarks are disclosed with regard to the above embodiment. (Supplementary Note 1)

[0042] The present disclosure is characterized in that the stator (10) comprises: the core (12); the coil (14) which is provided on the core and comprises the coil end section (14E) which projects out of the end section (12E) of the core in the axial direction (DA) of the core; a cylindrical element (16) which is in contact with the end section of the core and covers the outer circumference of the coil end section; a molding resin (18) with which the interior of the cylindrical element is filled; and an elastic element (20) which is arranged between the cylindrical element and the molding resin, wherein the elastic element is in close contact with the cylindrical element and the molding resin. (Supplementary Note 2)

[0043] In the stator according to supplementary note 1, the elastic element can comprise the adhesive layer (20LY) on each of the surfaces facing the mold resin and the surface facing the cylindrical element. (Supplementary Note 3)

[0044] In the stator according to supplementary note 1 or 2, the elastic element can be arranged circumferentially over the entire circumference of the cylindrical element. (Supplementary Note 4)

[0045] In the stator according to one of the supplementary notes 1 to 3, the elastic element can be arranged between at least a part of the surface of the coil end section and the molding resin and be in close contact with the coil end section and the molding resin. (Supplementary Note 5)

[0046] The stator according to supplementary note 3 or 4 may further comprise the multiple elastic elements, and the multiple elastic elements may be arranged at intervals in the axial direction. (Supplementary Note 6)

[0047] The stator according to supplementary note 1 or 2 may further comprise the multiple elastic elements, and the multiple elastic elements may be arranged at intervals in the circumferential direction of the cylindrical element. (Supplementary Note 7)

[0048] In the stator according to supplementary note 6, the multiple elastic elements can be arranged at intervals in the axial direction. (Supplementary Note 8)

[0049] The present disclosure is characterized by the method for manufacturing the stator, the method comprising: the filling step of filling the molten resin (22) into the interior of the cylindrical element which is attached to each of the two end sections of the core in the axial direction of the core; the cooling step of cooling the molten resin in order to harden the molten resin;and the cutting step in which the outer circumferential surface of the cylindrical element is cut until the height difference between the outer circumferential surface of the cylindrical element and the outer circumferential surface of the core becomes equal to or less than the permissible value, wherein each of the cylindrical elements is in axial contact with the end section of the core before being filled with the molten resin in the filling step, and covers the outer circumference of the coil end section projecting from the end section, wherein the elastic element is bonded to the inner surface of each of the cylindrical elements and the cutting in the cutting step is carried out in a state in which the elastic element bonded to the inner surface of the cylindrical element is in close contact with the mold resin obtained by curing the molten resin. (Supplementary Note 9)

[0050] In the method for manufacturing the stator according to Supplementary Note 8, the elastic element can also be bonded to the surface of the coil end section before filling with the molten resin in the filling step, and the cutting in the cutting step can be carried out in a state in which the elastic element bonded to the inner surface of the cylindrical element and to the surface of the coil end section is in close contact with the molding resin. (Supplementary Note 10)

[0051] In the method for manufacturing the stator according to supplementary note 8 or 9, the elastic element may have the adhesive layer on the surface on the mold resin side, and the cutting in the cutting step may be carried out in a state in which the elastic element is also bonded to the mold resin. (Supplementary Note 11)

[0052] The present disclosure is characterized by the method for manufacturing the stator, the method comprising: the step of filling the interior of the cylindrical element attached to each of the two end sections of the core in the axial direction of the core; the cooling step of cooling the molten resin to harden the molten resin; and the cutting step of cutting the outer circumferential surface of the cylindrical element, wherein, after the cooling step, the adhesive is filled into the gap between each of the cylindrical elements that are in axial contact with the end section of the core and covers the outer circumference of the coil end section projecting from the end section and the molded resin obtained by hardening the molten resin, and the cutting step is carried out in a state in which the cylindrical element and the molded resin are bonded together by the adhesive. (Supplementary Note 12)

[0053] In the method for manufacturing the stator according to Supplementary Note 11, the adhesive can also be injected into the gap between at least part of the surface of the coil end section and the molding resin, and the cutting step can be carried out in a state in which the cylindrical element and the coil end section are joined with the molding resin.

[0054] Although the present disclosure has been described in detail, it is not necessarily limited to the respective embodiments. These embodiments may be subject to various additions, substitutions, modifications, partial deletions, and the like, provided they do not deviate from the essence and core of the present disclosure or from the spirit of the disclosure as it arises from the content of the claims and their equivalents. Furthermore, these embodiments may also be implemented in combination with one another. For example, in the embodiments described above, the sequence of individual operations and the order of individual processes are given only as examples, and the present invention is not necessarily limited to these examples. The same applies if numerical values ​​or mathematical expressions are used in the description of the aforementioned embodiments. REFERENCE MARK LIST 10 Stator 12 core 14 coil 14E Coil end section 16 cylindrical element 18 Molding resin 20 elastic element 22 molten resin QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] JP 2004-120923 A

[0002]

Claims

[1] Stator, comprising: a core; a coil provided on the core, which has a coil end section that protrudes from an end section of the core in an axial direction of the core; a cylindrical element that is in contact with the end section of the core and covers an outer circumference of the coil end section; a molding resin with which an interior of the cylindrical element is filled; and an elastic element that is arranged between the cylindrical element and the molding resin, wherein the elastic element is in close contact with the cylindrical element and the molding resin. [2] Stator according to claim 1, wherein the elastic element has an adhesive layer on each of the surfaces of the elastic element facing the mold resin and on a surface facing the cylindrical element. [3] Stator according to claim 1 or 2, wherein the elastic element is arranged over the entire circumference of the cylindrical element in the circumferential direction of the cylindrical element. [4] Stator according to one of claims 1 to 3, wherein the elastic element is arranged between at least a part of a surface of the coil end section and the molding resin and is in close contact with the coil end section and the molding resin. [5] Stator according to claim 3 or 4, further comprising several elastic elements, wherein the several elastic elements are arranged at intervals in the axial direction. [6] Stator according to claim 1 or 2, further comprising a plurality of elastic elements, wherein the plurality of elastic elements are arranged at intervals in the circumferential direction of the cylindrical element. [7] Stator according to claim 6, wherein the multiple elastic elements are arranged at intervals in the axial direction. [8] Method for manufacturing a stator, the method comprising: a filling step in which molten resin is filled into an interior of a cylindrical element that is attached to each of the two end sections of a core in the axial direction of the core; a cooling step to cool the molten resin in order to harden the molten resin; and a cutting step to cut an outer circumferential surface of the cylindrical element until a height difference between the outer circumferential surface of the cylindrical element and an outer circumferential surface of the core becomes equal to or less than an acceptable value, wherein each of the cylindrical elements is in axial contact with the end section of the core prior to filling with the molten resin in the filling step and covers an outer circumference of a coil end section projecting from the end section, and an elastic element is attached to an inner surface of each of the cylindrical elements, and wherein the cutting in the cutting step is carried out in a state in which the elastic element adhering to the inner surface of the cylindrical element is in close contact with a mold resin obtained by curing the molten resin.

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