Stator core of electric motor and electric motor

Abstract

This invention relates to a stator core of an electric motor with improved water resistance and the electric motor itself. The stator core of the electric motor comprises: a first core block and a second core block, wherein the first core block and the second core block are stacked with a plurality of large-diameter thin plates and are flipped together such that the outer peripheral burrs of the large-diameter thin plates of the first core block and the outer peripheral burrs of the large-diameter thin plates of the second core block are opposite to each other; and a small-diameter thin plate sandwiched between the first core block and the second core block and having an outer diameter smaller than that of the large-diameter thin plates.

Description

Technical Field

[0001] The present invention relates to a motor, and more particularly to a stator core and a motor with improved waterproofness. Background Art

[0002] When a stator core is manufactured by laminating a plurality of thin plates obtained by punching electromagnetic steel sheets, punching burrs are formed on the peripheral edge portions of the thin plates. As a prior art related to the burrs, the following documents are known.

[0003] The following is disclosed in Japanese Patent Gazette No. 2016-32331: For a stator core formed by stacking multiple core plates formed by punching electromagnetic steel plates from one plate surface side with a movable die, a core plate with a plate surface facing one axial side and a core plate with a plate surface facing the other axial side are alternately stacked in the axial direction, and adhesive material is filled in the gaps between the stacked core plates.

[0004] The following is disclosed in Japanese Patent Gazette No. 2009-65831: a thin sheet stack is divided into two partial thin sheet stacks, and the two partial thin sheet stacks are combined to form a thin sheet stack in a manner such that the punching burrs at the joints of adjacent thin sheets are oriented in the direction of separation from each other, thereby suppressing the axial error or width error of the thin sheet stack.

[0005] Japanese Patent Application Laid-Open No. 2004-140966 discloses that the thickness of the peripheral portion of a punched electromagnetic steel sheet is made smaller than the difference between the thickness of the electromagnetic steel sheet and the height of burrs generated during punching, thereby preventing poor insulation between the electromagnetic steel sheets due to burrs.

[0006] A waterproof electric motor is disclosed in Japanese Patent Gazette No. 7-163083, in which a shell covering the outer circumferential surface of a stator core is omitted. The motor has a front support member and a rear support member for clamping the stator core, and each support member has an annular protrusion protruding radially outward from the outer circumferential surface near each end surface adjacent to the stator core. A sealant is applied and cured in a manner covering the outer circumferential surfaces of the two support members located between the annular protrusions and the outer circumferential surface of the stator core.

[0007] Japanese Patent Application Laid-Open No. 4-244748 discloses a stator yoke in which a plurality of thin plates are stacked so that burrs generated from cut surfaces of adjacent thin plates cover fracture surfaces recessed from peripheral edges of the thin plates.

[0008] The following contents are disclosed in Japanese Patent Gazette No. 53-89902: a pair of steel plates with different protruding directions of "burrs" generated by stamping are overlapped alternately, and only the butt joint portions of a pair of steel plates where the "burrs" are butted against each other are short-circuited, thereby preventing the edge portions of multiple overlapping steel plates from being short-circuited completely.

[0009] A stator core is disclosed in Japanese Patent Laid-Open No. 2000-341913. By alternately laminating two types of stator blanks with different outer diameters, the blanking end faces of the stator blanks are formed in a misaligned manner to prevent eddy currents caused by the blanking end faces. Summary of the Invention

[0010] Problems to be Solved by the Invention

[0011] Fig.9A is a partial cross-sectional view of the stator core, Fig. 9B is a partial side view of the stator core. When manufacturing a stator core by laminating a plurality of thin plates 90, in order to improve motor characteristics (especially reducing cogging torque by using segmented skewing (Japanese: 段スキュー)), there are cases where the thin plates 90 are turned over and laminated. At this time, as shown by the dashed line 91, at the portion where the tips of the burrs 92 formed on the thin plates 90 face each other, a large gap is generated between the burrs 92. This gap is 10 μm or more, and there are also cases where it reaches 70 - 80 μm due to time change. Therefore, it affects the waterproofness of the stator core. Especially when a motor that omits the housing covering the outer peripheral surface of the stator core is applied to a machine tool or the like, there are cases where cutting fluid or the like invades the motor from the direction shown by the arrow 93.

[0012] Therefore, a technique for improving motor characteristics and at the same time improving the waterproofness of the stator core is sought.

[0013] Solutions to the Problems

[0014] One technical solution of the present disclosure provides a stator core, which includes: a first core block and a second core block, the first core block and the second core block are laminated with a plurality of large-diameter thin plates and are turned over and arranged in such a way that the outer peripheral burrs of the large-diameter thin plates of the first core block face the outer peripheral burrs of the large-diameter thin plates of the second core block; and small-diameter thin plates, which are sandwiched between the first core block and the second core block and have an outer diameter smaller than that of the large-diameter thin plates.

[0015] In one technical solution of the present disclosure, it may also be that the stator core of the motor further has a sealant on its outer peripheral surface.

[0016] In one technical solution of the present disclosure, it may also be that the small-diameter thin plate has an outer peripheral burr and an inner peripheral burr, the inner peripheral burr projects in the opposite direction to the outer peripheral burr, and the inner peripheral burr of the small-diameter thin plate is received in the gap between the thin plates.

[0017] In one technical solution of the present disclosure, it may also be that the small-diameter thin plate has an outer peripheral burr and an inner peripheral burr, and the inner peripheral burr projects in the same direction as the outer peripheral burr.

[0018] In one technical solution of the present disclosure, the inner peripheral burrs of the large diameter thin plate and the outer peripheral burrs of the large diameter thin plate may protrude in the same direction, and the inner diameter of the small diameter thin plate may be larger than that of the large diameter thin plate.

[0019] In one technical solution of the present disclosure, a segmented skew may be formed between the first core block and the second core block by utilizing a flip configuration.

[0020] In one technical solution of the present disclosure, the stator core of the motor may include: a first core assembly, which includes a first core block, a second core block and a small diameter thin plate; and a second core assembly, which has the same structure as the first core assembly and forms a segmented twist between the second core assembly and the first core assembly.

[0021] In one aspect of the present disclosure, the stator core of the motor may further include an inter-assembly thin plate between the first core assembly and the second core assembly, and the inner diameter of the inter-assembly thin plate may be larger than the inner diameter of the large-diameter thin plate.

[0022] Another technical solution of the present disclosure provides an electric motor in which a housing covering an outer peripheral surface of a stator core is omitted, and the electric motor includes the stator core of the present disclosure.

[0023] Effects of the Invention

[0024] The invention improves the motor characteristics and simultaneously improves the waterproofness of the stator core. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a side view of the electric motor according to one embodiment.

[0026] Figure 2A This is a plan view showing the front side of a large-diameter thin plate according to one embodiment.

[0027] Figure 2B This is a plan view showing the back side of a large-diameter thin plate according to one embodiment.

[0028] Figure 3 This is a partial cross-sectional view of a stator core according to one embodiment.

[0029] Figure 4 It is a cross-sectional view showing a modified example of the stator core.

[0030] Figure 5 It is a cross-sectional view showing a modified example of a small-diameter thin plate.

[0031] Figure 6 It is a cross-sectional view showing another modified example of the stator core.

[0032] Figure 7 It is a cross-sectional view showing a modified example of a large-diameter thin plate.

[0033] Figure 8 It is a cross-sectional view showing another modified example of the stator core.

[0034] Fig.9A It is a partial cross-sectional view of the stator core.

[0035] Fig. 9B It is a partial side view of the stator core. DETAILED DESCRIPTION

[0036] Hereinafter, the embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In each figure, the same or similar components are given the same or similar figure marks. In addition, the embodiments described below do not limit the technical scope of the invention described in the claims and the meaning of the terms. In this specification, it should be noted that the term "front" refers to the load side and output side of the motor, and the term "rear" refers to the opposite side of the load and output of the motor.

[0037] Figure 1 It is a side view of the electric motor 10 of the present embodiment. It should be noted that the electric motor 10 of the present embodiment is a servo motor for machine tools, industrial robots, etc., but is not limited to this. As long as the housing covering the outer peripheral surface of the stator core is omitted, it can also be applied to other electric motors. The electric motor 10 includes a stator core 13, and the stator core 13 is sandwiched between the front housing 11 and the rear housing 12. The stator core 13 includes: a first core block 20, a second core block 21, and a small diameter thin plate 22, and the small diameter thin plate 22 is sandwiched between the first core block 20 and the second core block 21. The first core block 20 and the second core block 21 are stacked with a plurality of large diameter thin plates formed by punching and processing electromagnetic steel plates (refer to Figure 2A and Figure 2B ). The outer diameter of the small diameter thin plate 22 is smaller than the outer diameter of the large diameter thin plate as a whole at the outer periphery of the large diameter thin plate.

[0038] Figure 2A 3 is a top view showing the front side of the large-diameter thin plate 30. Figure 2B : is a top view showing the back side of the large diameter thin plate 30. The large diameter thin plate 30 is formed by approximately three punching steps. In the first step, the rotor portion of the motor 10 (not shown) is punched out, in the second step, the inner shape portion and the notch portion of the large diameter thin plate 30 are punched out, and in the third step, the outer shape portion of the large diameter thin plate 30 is punched out. In this example, since the inner shape portion and the notch portion of the large diameter thin plate 30 are punched out from the front side to the back side of the electromagnetic steel sheet, the inner peripheral edge burr of the large diameter thin plate 30 (see Figure 3 ) is formed on the back side of the large diameter thin plate 30. In addition, since the outer shape portion of the large diameter thin plate 30 is punched from the back side of the electromagnetic steel sheet to the front side, the outer peripheral burr of the large diameter thin plate 30 (see Figure 3) is formed on the front side of the large-diameter thin plate 30.

[0039] In addition, the large diameter thin plate 30 preferably has a plurality of pole teeth 31 at asymmetric positions. Thus, for example, when two large diameter thin plates 30 are reversed and arranged, the plurality of pole teeth 31 are circumferentially offset between the thin plates, thereby forming a stepwise skew.

[0040] Figure 3 FIG. 1 is a partial cross-sectional view of the stator core 13 of the present embodiment. Figure 3 Only six large-diameter thin plates 30 are shown, but it should be noted that about 140 to 150 thin plates are stacked in the stator core as a whole. It should also be noted that for ease of understanding, the burrs are depicted as relatively large in the present disclosure. The first core block 20 stacks a plurality of large-diameter thin plates 30 in such a manner that the outer peripheral burrs 30a of the large-diameter thin plates 30 face the same direction. The second core block 21 has the same structure as the first core block 20, but the first core block 20 and the second core block 21 are flipped in such a manner that the outer peripheral burrs 30a of the large-diameter thin plates 30 of the first core block 20 and the outer peripheral burrs 30a of the large-diameter thin plates 30 of the second core block 21 are opposite to each other. As described above, the plurality of pole teeth 31 (see Figure 2A and Figure 2B ) are offset in the circumferential direction, so that a segmented skew is formed between the first core block 20 and the second core block 21. As a result, the cogging effect of the motor 10 is reduced.

[0041] A sealant 40 is applied to the outer circumferential surface of the stator core 13, and a coating agent 41 is further applied to the outer circumferential surface of the sealant 40. Since the burr tips do not collide with each other on the outer circumferential surface of the first core block 20 and the outer circumferential surface of the second core block 21, it is difficult to form a gap. Therefore, for the electric motor in which the housing covering the outer circumferential surface of the stator core 13 is omitted, the sealant 40, the coating agent 41, etc. are used to ensure waterproofness. However, since the burr tips collide with each other on the outer circumferential surface of the core block 42 indicated by the dotted line, a small-diameter thin plate 22 having an outer diameter B smaller than the outer diameter A of the large-diameter thin plate 30 is inserted into the core block 42, thereby eliminating a relatively large gap and improving waterproofness.

[0042] In addition, the small diameter thin plate 22 has an outer peripheral burr 22a and an inner peripheral burr 22b, and the inner peripheral burr 22b protrudes in the opposite direction to the outer peripheral burr 22a. The inner diameter C of the small diameter thin plate 22 in this example is the same as the inner diameter D of the large diameter thin plate 30. Since the gap between the thin plates on the protruding side of the inner peripheral burr 22b of the small diameter thin plate 22 is narrower than the gap between other thin plates, it is possible that the top of the inner peripheral burr 22b of the small diameter thin plate 22 pushes the adjacent large diameter thin plate 30 outward, and a secondary gap is generated on the outer peripheral surface of the core block 42 represented by the dotted line. Therefore, the inner peripheral burr 22b of the small diameter thin plate 22 is preferably set to be smaller than the outer peripheral burr 30a of the large diameter thin plate 30, so as to be accommodated in the gap between the thin plates. The burr height can be controlled by adjusting the gap between the punch and the die, adjusting the thickness between the small diameter thin plate 22 and the large diameter thin plate 30, etc. (making the thickness of the small diameter thin plate 22 thinner than the thickness of the large diameter thin plate 30, etc.).

[0043] Figure 4 2 is a cross-sectional view showing a modified example of the stator core 13. The stator core 13 of this example comprises: a first core assembly 50 having a first core block 20, a second core block 21 and a small-diameter thin plate 22; and a second core assembly 51 having the same structure as the first core assembly 50 and forming a segmented skew between the first core assembly 50. Since the top ends of the burrs also collide with each other between the core assemblies 43 indicated by the dotted lines, an inter-assembly thin plate 23 having an inner diameter E larger than the inner diameter D of the large-diameter thin plate 30 is inserted into the inter-assembly thin plate 23 between the core assemblies 43, thereby eliminating a relatively large gap and improving waterproofness.

[0044] Figure 5 2 is a cross-sectional view showing a modified example of a small diameter thin plate. The inner peripheral burr 24b of the small diameter thin plate 24 of this example and the outer peripheral burr 24a of the small diameter thin plate 24 protrude in the same direction, which is different from the above-mentioned example. Since the gap between the thin plates on the protruding side of the inner peripheral burr 24b of the small diameter thin plate 24 is wider than the gap between other thin plates, the top of the inner peripheral burr 24b of the small diameter thin plate 24 will not push the adjacent large diameter thin plate 30 outward. As a result, it is difficult to generate a secondary gap on the outer peripheral surface of the core block 42 represented by the dotted line. In addition, the small diameter thin plate 24 of this example does not need to control the burr height.

[0045] Figure 62 is a cross-sectional view showing another modified example of the stator core 13. The stator core 13 of this example comprises: a first core assembly 52 having a first core block 20, a second core block 21 and a small-diameter thin plate 24; and a second core assembly 53 having the same structure as the first core assembly 52 and forming a segmented skew between the second core assembly 53 and the first core assembly 52. ​​Since the top ends of the burrs also collide with each other between the core assemblies 43 indicated by the dotted lines, an inter-assembly thin plate 25 having an inner diameter E larger than the inner diameter D of the large-diameter thin plate 30 is inserted between the core assemblies 43, thereby eliminating a relatively large gap and improving waterproofness.

[0046] Figure 7 2 is a cross-sectional view showing a modified example of a large diameter thin plate. In this example, the inner peripheral burr 32b of the large diameter thin plate 32 and the outer peripheral burr 32a of the large diameter thin plate 32 protrude in the same direction and the inner diameter C of the small diameter thin plate 26 is larger than the inner diameter D of the large diameter thin plate 32, which is different from the above example. Thus, since the top of the inner peripheral burr 32b of the large diameter thin plate 32 does not collide with the top of the inner peripheral burr 26b of the small diameter thin plate 26, it is difficult to generate a secondary gap on the outer peripheral surface of the core block 42 represented by the dotted line. In addition, the small diameter thin plate 26 of this example does not need to control the burr height.

[0047] Figure 8 2 is a cross-sectional view showing another modified example of the stator core 13. The stator core 13 of this example includes: a first core assembly 54 having a first core block 27, a second core block 28, and a small-diameter thin plate 26; and a second core assembly 55 having the same structure as the first core assembly 54. In this example, since the burr tips do not collide with each other between the core assemblies 43 indicated by the dotted lines, it is not necessary to insert an inter-assembly thin plate between the core assemblies.

[0048] According to the above embodiment, the stator core 13 with improved waterproofness between core blocks can be provided by using the small diameter thin plates 22, 24, 26. In addition, the waterproofness between core blocks can also be improved by using the inter-assembly thin plates 23, 25. In particular, the stator core 13 of the present disclosure is useful for an electric motor in which a housing covering the outer peripheral surface of the stator core is omitted.

[0049] It should be noted that although various embodiments have been described in this specification, the present invention is not limited to the above-described embodiments, and various modifications can be made within the scope described in the claims.

Claims

1. A stator core of an electric motor, characterized in that: The stator core of the motor has: A first core block and a second core block, wherein a plurality of large-diameter thin plates are stacked and flipped so that the outer peripheral burrs of the large-diameter thin plates of the first core block and the outer peripheral burrs of the large-diameter thin plates of the second core block face each other; as well as a small-diameter thin plate which is sandwiched between the first core block and the second core block and has an outer diameter smaller than that of the large-diameter thin plate, The small-diameter thin plate is disposed between the first core block and the second core block, and the outer peripheral burr of the first core block and the outer peripheral burr of the second core block are opposite to each other in the inter-core block.

2. The stator core of the electric motor according to claim 1, characterized in that: The stator core of the motor further includes a sealant on the outer peripheral surface.

3. The stator core of the electric motor according to claim 1 or 2, characterized in that: The small-diameter thin plate has an outer peripheral burr and an inner peripheral burr, the inner peripheral burr and the outer peripheral burr protrude in opposite directions, and the inner peripheral burr of the small-diameter thin plate is accommodated in a gap between the thin plates.

4. The stator core of the electric motor according to claim 1 or 2, characterized in that: The small-diameter thin plate has an outer peripheral burr and an inner peripheral burr, and the inner peripheral burr and the outer peripheral burr protrude in the same direction.

5. The stator core of the electric motor according to claim 1 or 2, characterized in that: The inner peripheral burr of the large-diameter thin plate and the outer peripheral burr of the large-diameter thin plate protrude in the same direction, and the inner diameter of the small-diameter thin plate is larger than the inner diameter of the large-diameter thin plate.

6. The stator core of the electric motor according to claim 1 or 2, characterized in that: The flipped configuration is used to form a segmented skew between the first core block and the second core block.

7. The stator core of the electric motor according to claim 1 or 2, characterized in that: The stator core of the motor comprises: a first core assembly comprising the first core block, the second core block and the small-diameter thin plate; and a second core assembly having the same structure as the first core assembly and forming a segmented skew between the second core assembly and the first core assembly.

8. The stator core of the motor according to claim 7, characterized in that: The stator core of the motor further includes an inter-assembly thin plate between the first core assembly and the second core assembly, wherein the inner diameter of the inter-assembly thin plate is larger than the inner diameter of the large-diameter thin plate.

9. An electric motor, wherein a housing covering the outer peripheral surface of a stator core is omitted, characterized in that: This electric motor includes the stator core according to any one of claims 1 to 8.

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