Magnetic yoke and method for manufacturing a magnetic yoke

Abstract

A magnetic yoke in which burrs generated when an insulator is formed on a divided magnetic yoke are suppressed. The magnetic yoke is configured by arranging a plurality of divided magnetic yokes 10 in a ring shape, the divided magnetic yoke 10 having a rear yoke portion 11 integrally formed by laminating a plurality of magnetic steel sheets and extending in a circumferential direction of the yoke, a single tooth portion 12 extending in a radial direction of the yoke from the rear yoke portion 11, and an insulator 13 covering an area from the tooth portion 12 to the rear yoke portion 11 and formed of an insulating resin. When viewed in an axial direction of the yoke, the insulator 13 has an outer edge region 13E in which a thickness is stepwise reduced as a position is closer to an end portion of the rear yoke portion 11.

Description

Technical Field

[0001] This invention relates to magnetic yokes and methods for manufacturing magnetic yokes. Background Technology

[0002] Previously, the technique described in Patent Document 1 was known as dividing the magnetic yoke that constitutes the stator of an electric motor into sections for each tooth, inserting the divided magnetic yoke into a metal mold, and filling the interior of the metal mold with resin to integrally form an insulator on the outer circumference of the teeth.

[0003] In the technology described in Patent Document 1, in the segmented magnetic yoke (stator core in Patent Document 1) divided by each tooth, the ends of the magnetic yoke are connected by a connecting part, and multiple teeth are unfolded in the opening direction. In this unfolded state, multiple segmented magnetic yokes are fixed inside the metal mold, and resin is filled into the metal mold, thereby forming resin integrally on the outer circumference of the teeth.

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2006-180698 Summary of the Invention

[0006] As shown in Patent Document 1, in a structure in which multiple segmented yokes are fixed inside a metal mold and molten resin is filled inside the metal mold to form an insulator on the outer periphery of the teeth, a portion of the resin filled inside the metal mold flows out from the boundary between the outer surface of the segmented yokes and the inner surface of the metal mold, thus sometimes forming so-called burrs.

[0007] As a segmented yoke, for example, in a structure having a rear yoke portion and teeth integrally formed thereon, if an insulator is integrally formed using a metal mold for a region from the outer periphery of the teeth to a portion of the rear yoke portion, it is believed that a portion of the resin leaks out to the end of the rear yoke (the end in the direction along the circumferential direction of the yoke), thus forming a burr-like protrusion.

[0008] In such a burred structure, when the segmented yoke is configured in a ring shape to form a yoke, the burrs may cause a problem that hinders the connection between the ends of the yoke.

[0009] While burrs can be eliminated to some extent by improving the precision of metal molds, it is difficult to completely prevent their formation, and therefore improvements are desired.

[0010] For this reason, people seek to develop a magnetic yoke that can suppress the generation of burrs when forming an insulator on a split magnetic yoke, as well as a method for manufacturing the magnetic yoke.

[0011] The magnetic yoke of the present invention is characterized by the following aspects: the magnetic yoke is constructed by arranging a plurality of segmented magnetic yokes in a ring shape, wherein the segmented magnetic yokes have: a rear magnetic yoke portion, a single tooth portion, and an insulator, the rear magnetic yoke portion being integrally formed by stacking a plurality of magnetic steel plates and extending in the circumferential direction of the magnetic yoke; the single tooth portion extending radially from the rear magnetic yoke portion; the insulator covering the area from the tooth portion to the rear magnetic yoke portion and being formed of an insulating resin, and when viewed in the axial direction of the magnetic yoke, the insulator having an outer edge region whose thickness decreases stepwise the closer it is to the end of the rear magnetic yoke portion.

[0012] According to this characteristic structure, the insulator integrally formed on the outer surface of the segmented yoke has an outer edge region where the thickness decreases in a stepped manner towards the end of the rear yoke portion of the segmented yoke. Because of this structure, even when, for example, the segmented yoke is fixed inside a metal mold and molten resin is filled into the mold to form the insulator, the resin preferentially starts filling from the wider area when flowing to the outer edge region. Therefore, the resin flow temperature (temperature at the flow front) decreases in the stepped-narrowing region, thus suppressing the phenomenon of resin flowing out from the area where the insulator is to be formed, thereby suppressing the generation of burrs.

[0013] Therefore, a magnetic yoke is formed that suppresses burr generation when an insulator is formed on the segmented magnetic yoke. In particular, since burr generation is suppressed in this way, the burr removal operation can also be omitted.

[0014] As a structure based on the above structure, the number of steps forming the above-mentioned stepped shape can be three or more.

[0015] Therefore, when an insulator is formed on the outer surface of the segmented yoke using a metal mold, the flow of resin can be suppressed by the three-stage stepped portion, thereby effectively suppressing the generation of burrs.

[0016] As a structure based on the above structure, the outer edge region can be formed throughout the end of the rear yoke, extending along the axis of the yoke.

[0017] Therefore, since an outer edge region is formed at the end of the rear yoke over the entire width along the axis of the yoke, burrs can be suppressed in a wider area.

[0018] The manufacturing method of the magnetic yoke involved in this invention is characterized by the following aspects: the method is a method for manufacturing a magnetic yoke composed of multiple segmented magnetic yokes arranged in a ring, wherein multiple magnetic steel plates are stacked to integrally form the segmented magnetic yoke having a rear magnetic yoke portion extending in the circumferential direction of the magnetic yoke and a single tooth portion extending radially from the rear magnetic yoke portion; the segmented magnetic yoke is housed inside a metal mold; an insulator is formed by filling the internal space of the metal mold with molten insulating resin and allowing it to solidify; when viewed in the axial direction of the magnetic yoke, the insulator has an outer edge region in which the thickness decreases stepwise the closer to the end of the rear magnetic yoke portion; the segmented magnetic yoke with the insulator formed is arranged in a ring, and adjacent rear magnetic yoke portions are joined together.

[0019] Thus, by fixing the segmented yoke inside a metal mold, filling the inside of the metal mold with molten resin, and allowing it to solidify, an insulator is formed in an outer edge region near the end of the rear yoke on the outer surface of the segmented yoke, where the thickness decreases in a stepped manner. Furthermore, when using a metal mold to form the insulator in this way, since the resin preferentially fills from the wider area when flowing to the outer edge region, the resin flow temperature (temperature at the flow front) decreases in the stepped-narrowing region. This suppresses the phenomenon of resin flowing out from the area where the insulator should be formed, thereby suppressing the generation of burrs. Then, the segmented yoke, in which the insulator is integrally formed, is arranged in a ring shape to complete the yoke.

[0020] Therefore, a method for manufacturing a magnetic yoke that suppresses burr formation when forming an insulator on the yoke has been obtained. In particular, since burrs are suppressed in this way, the burr removal process can be omitted. Attached Figure Description

[0021] Figure 1 This is a cross-sectional view showing the yoke of an electric motor.

[0022] Figure 2 A cross-sectional view of a segmented magnetic yoke with coiled wire wound around it.

[0023] Figure 3 A three-dimensional view of a segmented magnetic yoke.

[0024] Figure 4 This is a cross-sectional top view of the insulator formed in the rear yoke.

[0025] Figure 5 A longitudinal side view of the insulator formed on the upper surface of the split yoke.

[0026] Figure 6 This is a cross-sectional top view of the rear magnetic yoke and the metal mold.

[0027] Figure 7 This is a longitudinal side view of the upper surface of the magnetic yoke and the metal mold. Detailed Implementation

[0028] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0029] [Basic Structure]

[0030] Figure 1 The cross-section of the electric motor is shown. Multiple (nine in this embodiment) segmented magnetic yokes 10 are arranged in a ring around the inner circumference of the cylindrical housing 1 centered on the axis X to form a magnetic yoke Y. This magnetic yoke Y forms a magnetic circuit and functions as the stator of the electric motor.

[0031] Furthermore, within the housing 1, a rotor 3 is disposed within the internal space of a ring-shaped magnetic yoke Y. This rotor 3 rotates integrally with a shaft 2, which is supported in a manner that allows it to rotate freely coaxially with the axis X. The rotor 3 functions as a rotor and is embedded with multiple permanent magnets 4. It should be noted that the housing 1 uses a non-magnetic material such as resin, but a magnetic material such as iron can also be used.

[0032] like Figures 1-3 As shown, in the segmented magnetic yoke 10, multiple magnetic steel plates are stacked to form a rear magnetic yoke portion 11 extending in the circumferential direction of the magnetic yoke Y, and a single tooth portion 12 extending radially from the rear magnetic yoke portion 11 along the magnetic yoke Y. Furthermore, the segmented magnetic yoke 10 includes an insulator 13 made of insulating resin covering the area from the tooth portion 12 to the rear magnetic yoke portion 11, and a coil portion C is formed by winding a coil wire 14, such as copper wire, with an insulating coating formed on its outer periphery.

[0033] It is assumed that the insulator 13 is made of a thermoplastic resin that is a non-Newtonian fluid, but the resin forming the insulator 13 is not limited to a specific resin as long as it is an insulating resin.

[0034] like Figure 2 , Figure 3 As shown, in the rear yoke portion 11, a protrusion 11a is formed on one end of each end in the direction along the circumferential direction of the yoke Y, and a recess 11b is formed on the other end. It should be noted that the protrusion 11a is formed as a region protruding along the stacking direction of the magnetic steel plates, and the recess 11b is formed as a groove along the stacking direction of the magnetic steel plates. Thus, as... Figure 1 As shown, by fitting the convex portion 11a and the concave portion 11b together, the adjacent segmented magnetic yokes 10 are engaged, thereby maintaining the proper positional relationship.

[0035] [Insulator]

[0036] like Figures 1-5As shown, in the split magnetic yoke 10, the stator core is formed by stacking magnetic steel plates along the direction of the axis X, and a flange portion 12a is formed at the end of the protruding side of the tooth portion 12, which is wider in the circumferential direction than the tooth portion 12.

[0037] An insulator 13 is formed in the region from the protruding end of the tooth 12 to the rear yoke 11. A front end restricting portion 13a is integrally formed at the protruding end of the tooth 12, extending outward from the tooth 12 in a manner that surrounds the tooth 12. A base end restricting portion 13b is integrally formed at the base end of the tooth 12, extending in two directions (along both sides of the direction of the axis X) in the stacking direction.

[0038] Furthermore, the front end restricting portion 13a protrudes to both sides in the direction along the stacking direction of the magnetic steel plate at the protruding end of the tooth portion 12, and the base end restricting portion 13b protrudes to both sides in the direction along the stacking direction of the magnetic steel plate in the rear yoke portion 11 connected to the base end of the tooth portion 12. By forming the insulator 13 in this way, a coil wire 14 forming the coil portion C is wound between the front end restricting portion 13a and the base end restricting portion 13b in the region surrounding the tooth portion 12.

[0039] like Figure 3 , Figure 4 As shown, regarding the insulator 13, when viewed in the direction of the axis X, near the end of the rear yoke portion 11 of the split yoke 10 in the insulator 13, there is an outer edge region 13E whose thickness decreases in a stepwise manner as it approaches the end. This outer edge region 13E is formed on the surface of the rear yoke portion 11 of the split yoke 10 facing the tooth portion 12.

[0040] like Figure 4 As shown, the insulator 13 is formed with a thickness of reference value Ts relative to the outer surface of the segmented yoke 10. However, the outer edge region 13E is formed such that, near the boundary of the outer surface of the segmented yoke 10, the wall thickness gradually decreases from the reference value Ts to a first wall thickness value T1 and a second wall thickness value T2. Furthermore, the boundaries between the portion of the insulator 13 with a thickness of reference value Ts and the portion with a thickness of the first wall thickness value T1, and the boundaries between the portion with a thickness of the first wall thickness value T1 and the portion with a thickness of the second wall thickness value T2, are each formed with inclined surfaces 13s of the same inclination.

[0041] like Figure 6As shown, by housing and fixing a portion of the segmented yoke 10 inside the metal mold 20, and filling the interior of the metal mold 20 with molten insulating resin and allowing it to solidify, the insulator 13 and the segmented yoke 10 are integrally formed. Since the aforementioned outer edge region 13E is formed when the insulator 13 is integrally formed, the inner surface of the metal mold 20 is shaped in the region corresponding to the outer edge region 13E, such that a reference gap value Gs, a first gap value G1, and a second gap value G2 are formed between the outer surface of the segmented yoke 10 and the inner surface of the metal mold 20.

[0042] It should be noted that the reference gap value Gs (reference value Ts) is approximately 0.35 mm, the first gap value G1 (first wall thickness value T1) is approximately 0.25 mm, and the second gap value G2 (second wall thickness value T2) is approximately 0.15 mm. Therefore, compared to the resistance value of resin flowing in the region of the reference gap value Gs, the resistance value in the region of the first gap value G1 is greater, and the resistance value in the region of the second gap value G2 is further increased.

[0043] In addition, such as Figure 7 As shown, a space is formed in the metal mold 20 for forming the aforementioned front end side restriction portion 13a and base end side restriction portion 13b, wherein a gate 21 is formed for filling molten resin into the interior of the metal mold 20 from the outer periphery of the base end side restriction portion 13b.

[0044] [Using metal molds to form insulators]

[0045] Because the metal mold 20 is formed as follows Figure 6 , Figure 7 As shown in the structure, the molten resin filled from gate 21 flows in a manner that expands from the area near gate 21 to the surrounding area during the initial stage of filling. Furthermore, even if the resin intends to flow into the area of ​​the first gap value G1 during the initial stage of filling, since the resistance to resin flow in the area of ​​the first gap value G1 is greater than the resistance when the resin flows in the area of ​​the reference gap value Gs, the resin will first flow into the area of ​​the reference gap value Gs that is not filled with resin inside the metal mold 20.

[0046] Then, inside the metal mold 20, after the area forming the reference gap value Gs is almost completely filled with resin, although the resin will fill the area of ​​the first gap value G1, the flow of the resin in the area of ​​the second gap value G2 is suppressed because the resistance value of the resin when flowing in the area of ​​the second gap value G2 is large, and the pressure of the resin in this area is also reduced.

[0047] Therefore, inside the metal mold 20, a time delay is generated from the start of resin filling to the filling of the regions of the first gap value G1 and the second gap value G2. This not only suppresses the phenomenon of direct inflow of high-pressure resin, but also, because the resin pressure is greatly reduced when the resin flows in the region of the second gap value G2, it suppresses the undesirable situation of resin flowing out from the end of the second gap value G2 and generating burrs.

[0048] In particular, the outer edge region 13E is formed in a straight line near the end of the rear yoke 11 along the stacking direction of the magnetic steel plate, and the flow direction of the resin filled from the gate 21 is along the stacking direction of the magnetic steel plate. Therefore, even when the resin filled from the gate 21 flows near the regions of the first gap value G1 and the second gap value G2, the resin will preferentially flow along the stacking direction of the magnetic steel plate, thus suppressing the phenomenon of resin flowing to the regions of the first gap value G1 and the second gap value G2, and also effectively suppressing the generation of burrs.

[0049] [Methods for manufacturing magnetic yokes]

[0050] In manufacturing the magnetic yoke Y, as described above, an insulator 13 is formed by housing and fixing a portion of the segmented magnetic yoke 10 inside the metal mold 20 and filling the interior of the metal mold 20 with molten resin.

[0051] Next, coil wire 14 is wound around the outer surface of insulator 13 to form coil portion C. Multiple segmented magnetic yokes 10 with coil portion C formed are arranged in a ring shape. Then, the segmented magnetic yokes 10 are joined to form magnetic yoke Y.

[0052] [Effects of the Implementation Method]

[0053] A portion of the segmented magnetic yoke 10, formed by stacking magnetic steel plates, is housed and fixed inside a metal mold 20. Molten resin is then filled inside the metal mold 20 and cooled. An insulator 13 is then integrally formed firmly onto the segmented magnetic yoke 10 removed from the metal mold 20. Furthermore, by setting the shape of the inner surface of the metal mold 20, an outer edge region 13E is formed near the end of the rear magnetic yoke portion 11 in the insulator 13. This suppresses resin leakage to the outside at this end and prevents the formation of burrs.

[0054] Therefore, when connecting the ends of the rear yoke portions 11 of adjacent split yokes 10 to each other, the undesirable situation of burrs hindering the connection can be eliminated. For example, the assembly of the motor can be accelerated without performing the deburring operation.

[0055] Furthermore, by using a metal mold 20 to integrally form an insulator 13 on the segmented yoke 10, winding coil wire 14 around the outer surface of the insulator 13 to form a coil portion C, and arranging the segmented yoke 10 in a ring shape to manufacture the yoke Y, the assembly of the electric motor can be easily carried out.

[0056] [Other Implementation Methods]

[0057] In addition to the embodiments described above, the present invention may also be configured in the following manner (for parts that have the same function as those in the embodiments, common numbers and symbols are marked).

[0058] (a) can also be structured as follows: such as Figure 5 , Figure 7 As shown, by forming an outer edge region 13E in the rear yoke portion 11 at a position radially close to the outer periphery of the yoke Y with reference to the base end side restriction portion 13b, the generation of resin burrs is suppressed by utilizing this region.

[0059] like Figure 5 As shown, the structure of the outer edge region 13E in this other embodiment (a) is the same as that shown in the embodiment, and therefore the structure of the metal mold 20 is also as shown. Figure 7 As shown, the structure is the same as that shown in the embodiment.

[0060] As shown in this other embodiment (a), by suppressing the generation of burrs on the upper and lower surfaces of the rear yoke portion 11 in the insulator 13, the processing of the segmented yokes 10 when the yoke Y is constructed with a plurality of segmented yokes 10 becomes easier, and the burr removal operation is not required.

[0061] (b) In the embodiment, the number of steps in the outer edge region 13E is two, but it can also be three or more. In addition, when multiple steps are formed, from the viewpoint of suppressing the generation of burrs, it is also effective to increase the interval between the steps, so the interval between the steps can be arbitrarily set.

[0062] It should be noted that when setting the number of steps in the outer edge region 13E and the spacing between the steps, it is also possible to consider setting values ​​that conform to properties such as the flowability of the resin forming the insulator 13.

[0063] (c) In one embodiment, a portion of the dividing yoke 10 is fixed inside the metal mold 20, but the metal mold 20 may also fix the entire dividing yoke 10 inside. Regarding the shape and structure of the metal mold 20, shapes and structures other than those shown in the embodiment may be used.

[0064] (d) The magnetic yoke Y, which is integrally formed into the insulator 13 by the metal mold 20, is not limited to electric motors, but can also be used in generators.

[0065] [Industry availability]

[0066] The present invention can be used to form an insulator on a segmented yoke and to configure the segmented yoke into a ring-shaped yoke.

[0067] Symbol Explanation

[0068] 10. Segmented yoke

[0069] 11 Rear yoke

[0070] 12 teeth

[0071] 13 Insulators

[0072] 13E Outer Edge Region

[0073] 20 Metal molds

[0074] Y-shaped magnetic yoke.

Claims

1. A magnetic yoke configured by arranging a plurality of segmented magnetic yokes in a ring, wherein, The segmented magnetic yoke has: The rear magnetic yoke is integrally formed by stacking multiple magnetic steel plates and extends in the circumferential direction of the magnetic yoke. A single tooth, the single tooth extending radially from the rear yoke; as well as, An insulator covering the region from the teeth to the rear yoke and integrally formed of insulating resin. When viewed in the axial direction of the yoke, the insulator is formed with a thickness of a reference value relative to the outer surface of the tooth, and has an outer edge region in which the thickness decreases in a multi-step manner from the reference value as it approaches the end of the rear yoke.

2. The magnetic yoke as described in claim 1, wherein, The number of steps forming the stepped shape is three or more.

3. The magnetic yoke as described in claim 1 or 2, wherein, The outer edge region is formed throughout the end of the rear yoke, extending along the axis of the yoke.

4. A method for manufacturing a magnetic yoke, comprising manufacturing a magnetic yoke formed by arranging multiple segmented magnetic yokes in a ring shape, wherein, Multiple magnetic steel plates are stacked to integrally form a segmented magnetic yoke having a rear magnetic yoke portion extending in the circumferential direction of the yoke, and a single tooth portion extending radially from the rear magnetic yoke portion along the yoke. The segmented magnetic yoke is housed inside the metal mold. An insulator is formed by filling the internal space of the metal mold with molten insulating resin and allowing it to solidify. When viewed in the axial direction of the yoke, the insulator is formed with a thickness of a reference value relative to the outer surface of the teeth, and has an outer edge region where the thickness decreases in a multi-step manner from the reference value as it approaches the end of the rear yoke. The segmented magnetic yokes on which the insulator is formed are arranged in a ring shape, and the adjacent rear magnetic yoke portions are joined together.

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