Current transformer and method for manufacturing current transformer

Abstract

The present invention provides a current transformer having excellent temperature characteristics, capable of adjusting output voltage with high precision through gap adjustment, and reducing tolerance, and a method for manufacturing the same. The core component 31 for the current transformer of the present invention has an E-type core 40 and an I-type core 50, and the I-type core is overlapped on the connecting portion of the E-type core to form an integrated whole, the E-type core is formed of an electromagnetic steel sheet and has three legs 41, 42, 41 extending approximately in parallel and the connecting portion 43 connecting the ends of the legs, and the I-type core 50 is formed of an electromagnetic steel sheet and has approximately the same length as the connecting portion.

Description

Technical Field

[0001] The present invention relates to a current transformer for detecting current flowing through various AC devices for output control and overcurrent protection operation, and a method for manufacturing the same. Background Art

[0002] In high-power electrical equipment such as air conditioners and IH equipment that operate on household power supplies, current transformers are used to detect current. The current transformer has a primary coil and a secondary coil, and an iron core that forms a magnetic circuit common to these coils (for example, refer to Patent Document 1). In the current transformer, a current detection resistor is connected to the secondary coil, and the commercial frequency of the power supply of the equipment is energized to the primary coil, and the potential difference across the terminal resistor for current detection of the secondary coil generated by the magnetic circuit according to the current change on the primary side is detected as a voltage. The device imports this voltage into a microcomputer to control the inverter circuit, etc., and perform input and output control of the device.

[0003] The core of the current transformer is formed by laminating cores made of electromagnetic steel sheets. Figure 6 The magnetic circuit is formed by alternately stacking an E-shaped core (E-type core) and an I-shaped core (I-type core). By alternately stacking (i.e., stacking in a changing direction) the E-type core and the I-type core, the leakage flux is reduced, the magnetic efficiency is improved, and the decrease in the secondary output voltage caused by the increase in the primary current is suppressed. However, due to the deviation in the gap formed between the joint surfaces of the E-type core and the I-type core, there is a problem of deviation in the secondary output voltage. On the other hand, in order to fix the E-type core and the I-type core to each other, resin or varnish is required, but due to the thermal expansion and thermal contraction of the resin or varnish, the deviation of the secondary output voltage caused by the temperature change is further increased. That is, the temperature characteristics of the current transformer are not sufficient.

[0004] Therefore, in Patent Document 1 Figure 1 , Figure 2 In , a core in which the alternately inserted I-type core is omitted and only the E-type cores are alternately stacked in such a way that the front ends of the legs overlap is proposed. Since the I-type core is omitted and there is no gap in this current transformer, it is not easily affected by thermal expansion and thermal contraction and has excellent temperature characteristics.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent document 1: Japanese Utility Model Application Laid-Open No. 63-18824. Summary of the invention

[0008] Problems to be solved by the invention

[0009] For example, since the current that can be used in a household power supply is specified by the circuit breaker, in order to operate these electrical devices at maximum output, it is necessary to detect the current value and control so that the sum of the current values ​​of these electrical devices does not exceed the maximum current value of the circuit breaker. At this time, if there is an error in the current value detected by the current transformer, the electrical device has to be operated at a lower total current value for safety reasons. Therefore, it is required to accurately detect the current value through the current transformer and increase the output of the electrical device to the maximum within the maximum range without exceeding the maximum current value of the circuit breaker.

[0010] However, in Patent Document 1 Figure 1 , Figure 2 In the current transformer shown, there is no I-type core, and the front end of the leg of the E-type core is open, so the leakage flux between the legs becomes larger and the magnetic saturation becomes faster. As a result, as the primary current increases, the drop in the secondary output voltage becomes larger, so the size of the core needs to be increased.

[0011] In addition, the output voltage can be adjusted by adjusting the gap formed between the E-type iron core and the I-type iron core, but in this current transformer, since there is no gap, the output voltage cannot be adjusted. Furthermore, considering the deviation of the magnetic properties of the iron core material and the temperature deviation in the annealing process of heat treating the iron core, the tolerance of the secondary output voltage needs to be set larger (for example, effective value ±3% to 5%).

[0012] An object of the present invention is to provide a current transformer having excellent temperature characteristics and capable of adjusting an output voltage with high accuracy and reducing tolerance by gap adjustment, and a method for manufacturing the same.

[0013] Solutions to Solve Problems

[0014] The iron core component for a current transformer of the present invention comprises:

[0015] An E-shaped iron core formed of an electromagnetic steel plate and having three legs extending substantially in parallel and a connecting portion connecting ends of the legs; and

[0016] An I-type iron core is formed of an electromagnetic steel sheet and has substantially the same length as the connecting portion.

[0017] The I-type core is overlapped and integrated on the connection portion of the E-type core.

[0018] In addition, the current transformer of the present invention has:

[0019] A resin bobbin having a through hollow portion and having a primary coil and a secondary coil wound thereon; and

[0020] An iron core, wherein the central legs of E-type iron cores are alternately stacked in reverse in the hollow portion of the bobbin and an I-type iron core is arranged between the connecting portions of the stacked E-type iron cores, the E-type iron core is formed of an electromagnetic steel sheet and has three legs extending approximately in parallel and the connecting portion connecting the ends of the legs, and the I-type iron core is formed of an electromagnetic steel sheet and has approximately the same length as the connecting portion,

[0021] The iron core is obtained by stacking the above-described iron core members for a current transformer by alternately inserting them into the hollow portion of the bobbin from a first direction and a second direction opposite to the first direction.

[0022] Preferably, the core components for current transformers are alternately inserted into the hollow portion of the bobbin from a first direction and a second direction opposite to the first direction and stacked, the core components for current transformers having an E-type core and an I-type core and being integrated by overlapping the I-type core on a connecting portion of the E-type core, the E-type core being formed by stamping and blanking an electromagnetic steel sheet and having three legs extending approximately in parallel and the connecting portion connecting ends of the legs, the I-type core being formed by stamping and blanking an electromagnetic steel sheet and having approximately the same length as the connecting portion,

[0023] The current transformer core components are stacked in the hollow portion of the bobbin alternately from a first direction and a second direction opposite to the first direction and in reverse directions, and the I-type core opposite to the E-type core is arranged in an opposite direction of withdrawal.

[0024] The end faces of the E-type iron core and the I-type iron core are processed by punching and blanking to form a rounded and smooth collapse at the corner, a shear surface with rib-like marks in the plate thickness direction by shearing, a fracture surface with sharp unevenness as if the material is peeled off, and a sawtooth burr protruding from the end face in the punching direction.

[0025] The E-type iron core and the I-type iron core may be arranged such that the shear surface and the fracture surface face each other.

[0026] A structure can be adopted in which the current transformer core members stacked in the hollow portion of the bobbin are integrated with each other.

[0027] The following structure can be adopted:

[0028] The current transformer core members inserted into the hollow portion of the bobbin from the first direction are integrated with each other in a stacked state.

[0029] The current transformer core members inserted into the hollow portion of the bobbin from the second direction are integrated with each other in a stacked state.

[0030] In addition, the manufacturing method of the current transformer of the present invention comprises:

[0031] a step of preparing a core component for a current transformer, wherein the core component for a current transformer is an E-type core and an I-type core, wherein the I-type core is integrated by overlapping the I-type core at a connecting portion of the E-type core, the E-type core being formed of an electromagnetic steel sheet and having three legs extending substantially parallel to each other and the connecting portion connecting ends of the legs, and the I-type core being formed of an electromagnetic steel sheet and having substantially the same length as the connecting portion;

[0032] a bobbin preparation step of preparing a resin bobbin having a through hollow portion and wound with a primary coil and a secondary coil;

[0033] a stacking step of inserting the leg portion at the center of the E-type core of the current transformer core component into the hollow portion of the bobbin alternately from a first direction and a second direction opposite to the first direction to stack the leg portion; and

[0034] The integration step integrates the stacked current transformers into a core component.

[0035] Preferably, the manufacturing method of the current transformer comprises:

[0036] A step of preparing a core component for a current transformer, wherein the core component for a current transformer is an E-type core and an I-type core, wherein the I-type core is integrated by overlapping the I-type core at a connecting portion of the E-type core, the E-type core being formed by punching and blanking an electromagnetic steel sheet and having three legs extending substantially parallel to each other and the connecting portion connecting ends of the legs, and the I-type core being formed by punching and blanking an electromagnetic steel sheet and having substantially the same length as the connecting portion;

[0037] a bobbin preparation step of preparing a resin bobbin having a through hollow portion and wound with a primary coil and a secondary coil; and

[0038] In the stacking step, the central leg of the E-type core of the current transformer core component is inserted into the hollow portion of the bobbin alternately and reversely from a first direction and a second direction opposite to the first direction, and the I-type core opposite to the E-type core is stacked in a manner opposite to the pulling-out direction.

[0039] Preferably, after the stacking step and before the integration step, a gap adjustment step is included, in which the stacked current transformer core components are pressed from the first direction and / or the second direction to adjust the gap formed between the front end of the leg of the E-type core of the current transformer core component inserted from the first direction and the end edge of the I-type core of the current transformer core component inserted from the second direction, and the gap formed between the front end of the leg of the E-type core of the current transformer core component inserted from the second direction and the end edge of the I-type core of the current transformer core component inserted from the first direction.

[0040] Preferably, the gap adjustment step performs the gap adjustment while referring to output voltage characteristics.

[0041] Effects of the Invention

[0042] The core component for a current transformer of the present invention is integrated by overlapping an E-type core and an I-type core in advance, so it is easy to handle and can be easily inserted into the bobbin of the current transformer.

[0043] In addition, the current transformer of the present invention can adjust the gap formed between the E-type core of the current transformer core component inserted into the bobbin from the first direction and the end edge of the I-type core of the current transformer core component inserted from the second direction, and the gap formed between the E-type core of the current transformer core component inserted from the second direction and the end edge of the I-type core of the current transformer core component inserted from the first direction. By enabling the gap adjustment, the output voltage of the current transformer can be adjusted with high precision, and the tolerance can be reduced as much as possible.

[0044] According to the manufacturing method of the current transformer of the present invention, the current transformer core component integrates the E-type core and the I-type core. Therefore, by inserting the current transformer core component into the hollow part of the bobbin from the first direction and the second direction, the current transformer core components are integrated with each other, so that the current transformer can be manufactured, and the manufacturing efficiency can be improved.

[0045] Furthermore, according to the manufacturing method of the current transformer of the present invention, it is possible to adjust the gap formed between the E-type core of the current transformer core component inserted into the bobbin from the first direction and the end edge of the I-type core of the current transformer core component inserted from the second direction, and the gap formed between the E-type core of the current transformer core component inserted from the second direction and the end edge of the I-type core of the current transformer core component inserted from the first direction. By enabling the gap adjustment, the output voltage of the current transformer can be adjusted with high precision, and the tolerance can be reduced as much as possible. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 is a perspective view showing a current transformer according to one embodiment of the present invention;

[0047] Figure 2 is an exploded perspective view of an iron core component for a current transformer of the present invention;

[0048] Figure 3 (a) a perspective view and (b) a cross-sectional view of a core component for a current transformer in which an E-type core and an I-type core are integrated by riveting;

[0049] Figure 4 A perspective view of an embodiment of an iron core component for a current transformer in which an E-type iron core and an I-type iron core are integrated by riveting and which has no guide hole;

[0050] Figure 5 The present invention is a perspective view of a core component for a current transformer in which an E-type core and an I-type core are integrated by welding, wherein (a) is an embodiment in which welding is performed on the end edge, and (b) is an embodiment in which welding is performed on the side surface;

[0051] Figure 6 is a plan view showing a region where the magnetic flux density is low when the current transformer core component is assembled into the current transformer;

[0052] Figure 7 is a side view showing a process of inserting a core member for a current transformer into a bobbin on which a primary coil and a secondary coil are wound;

[0053] Figure 8 is a longitudinal sectional view showing a process of inserting a core component for a current transformer into the bobbin;

[0054] Fig. 9 A side view showing a state in which all the current transformer core components are inserted into the bobbin and the current transformer core components inserted from the first direction and the current transformer core components inserted from the second direction are integrated by welding;

[0055] Fig.10 is a side view showing a process of adjusting a gap formed between a current transformer core component inserted and integrated from a first direction and a current transformer core component inserted and integrated from a second direction;

[0056] Fig.11 is a side view showing a state in which the current transformer core component inserted and integrated from the first direction and the current transformer core component inserted and integrated from the second direction are integrated by spot welding after the gap adjustment;

[0057] Fig.12is a side view showing an embodiment in which the current transformer core member inserted from the first direction and the current transformer core member inserted from the second direction are collectively integrated after the gap adjustment is performed;

[0058] Fig.13 1. A side view showing an embodiment in which the front and back overlapping order of stacked core components for a current transformer is changed;

[0059] Fig.14 The figures are enlarged views of the butt joint of an E-type iron core and an I-type iron core (both manufactured by stamping and blanking) facing each other with a gap, (a) showing an embodiment in which shear surfaces and fracture surfaces are butt jointed, and (b) showing an embodiment in which a shear surface and a fracture surface are butt jointed;

[0060] Fig.15 A perspective view showing a method of manufacturing a current transformer in which a current transformer core member inserted from a first direction and a current transformer core member inserted from a second direction are preliminarily divided into blocks and inserted into a bobbin;

[0061] Fig.16 is an exploded view of a current transformer module according to one embodiment of the present invention;

[0062] Fig.17 is a stereogram of a current transformer module;

[0063] Fig.18 is a cross-sectional view of a current transformer module;

[0064] Fig.19 is a bottom view of the upper shell;

[0065] Fig. 20 is a top view of the lower shell;

[0066] Fig.21 is a circuit diagram of a current transformer output voltage measuring circuit in an embodiment;

[0067] Fig. 22 is a three-dimensional diagram of a current transformer of Comparative Example 1;

[0068] Fig.23 is a three-dimensional diagram of a current transformer of Comparative Example 2;

[0069] Fig.24 is a three-dimensional diagram of a current transformer of Comparative Example 3;

[0070] Fig.25 is a graph showing the output voltage characteristics at -25°C, 25°C and 80°C of the inventive example (Example 1);

[0071] Fig.26is a graph comparing the output voltage characteristics of the inventive example, comparative example 1, and comparative example 2 (Example 2);

[0072] Fig. 27 Graphs showing the output voltage characteristics of Comparative Example 3 at -25°C, 25°C, and 80°C (Example 3). DETAILED DESCRIPTION

[0073] Hereinafter, a current transformer core member 31 (hereinafter referred to as “core member”), a current transformer 10 , and a current transformer module 12 according to an embodiment of the present invention will be described with reference to the drawings.

[0074] Figure 1 1 is a perspective view of a current transformer 10 according to an embodiment of the present invention. As shown in the figure, the current transformer 10 is configured by installing an iron core 30 forming a common magnetic path of the primary coil 26 and the secondary coil 27 on a resin bobbin 20 on which a primary coil 26 and a secondary coil 27 are wound. In the illustrated embodiment, the primary coil 26 is a U-shaped winding member, and the secondary coil 27 is a thin winding member wound on the bobbin 20, and the outer periphery is protected by tape.

[0075] The core 30 is formed by laminating a plurality of core members 31 . Figure 2 1 is an exploded perspective view of a core component 31 constituting the core 30. As shown in the figure, the core component 31 can be composed of an E-type core 40 and an I-type core 50. The E-type core 40 and the I-type core 50 can be obtained by stamping and punching electromagnetic steel sheets such as silicon steel sheets. For example, the electromagnetic steel sheet can be a thin strip-shaped electromagnetic steel sheet.

[0076] The E-type core 40 has three substantially rectangular legs 41, 42, 41 extending substantially in parallel and a substantially rectangular connection portion 43 connecting one end of these legs 41, 42, 41. In order to suppress leakage flux, the width dimension 43a of the connection portion 43 is preferably longer than the width dimension 41a of the leg 41. In addition, the I-type core 50 can be substantially rectangular in shape and substantially the same size as the connection portion 43. Preferably, guide holes 44, 51 for positioning are formed in the E-type core 40 and the I-type core 50. In addition, in order to align the positions of the I-type core 50 and the E-type core 40 and to facilitate overlapping, the dimension of the long dimension direction of the I-type core 50 is preferably 0.1 mm to 0.3 mm smaller than the dimension of the long dimension direction of the connection portion 43 of the E-type core 40.

[0077] The E-type core 40 and the I-type core 50 are integrated by overlapping the I-type core 50 on the connection portion 43 of the E-type core 40, thereby forming the core member 31. Regarding integration, for example, Figure 3 and Figure 4 The riveting 34 shown, Figure 5 Welding 35 is shown, bonding is not shown.

[0078] When the E-type iron core 40 and the I-type iron core 50 are integrated by riveting 34, as shown in FIG. Figure 2 As shown, a rivet hole 45 is formed in advance in one of the E-type iron core 40 or the I-type iron core 50, and a tenon 52 is formed in the other, as shown in FIG. Figure 3 (a) and Figure 3 As shown in (b), the E-type iron core 40 and the I-type iron core 50 are overlapped and the rivet hole 45 is aligned with the tenon 52 to perform riveting 34. The rivet hole 45 can be formed simultaneously when the E-type iron core 40 or the I-type iron core 50 is punched and blanked. When forming the rivet hole 45, in order to suppress the strength reduction and deformation of the iron core 30, the rivet hole 45 is preferably formed in the E-type iron core 40 with a large area.

[0079] In addition, when the E-type iron core 40 and the I-type iron core 50 are integrated by welding 35, as shown in FIG. Figure 5 As shown in (a), welding can be performed in a manner that spans the outer edge of the connection portion 43 of the E-type iron core 40 and the outer edge of the I-type iron core 50. Figure 5 As shown in (b), welding 35 is performed across both ends of the connection portion 43 of the E-type core 40 and both ends of the I-type core 50. Examples of welding 35 include laser welding, laser welding, and resistance welding (the same applies to welding described below), but are not limited thereto.

[0080] When the E-type iron core 40 and the I-type iron core 50 are integrated by the welding 35, the magnetic properties of the welded portion and its vicinity may be degraded. Figure 6 As shown, welding 35 is preferably performed in a region 46 of low magnetic flux density in the core member 31, that is, in a corner and a central portion near the outer end edge of the E-type core 40 and the I-type core 50. This region 46 is a region of low magnetic flux density in the magnetic circuit, so even if the magnetic characteristics are slightly reduced, the influence on the performance is suppressed.

[0081] like Figures 3 to 5 As shown in FIG. 1 , a plurality of core components 31 are prepared by integrating the E-type core 40 and the I-type core 50 (current transformer core component preparation step), and the core components 31 are mounted on the bobbin 20. The bobbin 20 is prepared as follows: Figure 7 As shown, a primary coil 26 wound in a U shape and a secondary coil 27 protected by a tape 27 b are provided, and a hollow portion 21 is formed in the bobbin 20 in a direction perpendicular to the coils 26 and 27 (bobbin preparation step).

[0082] Then, if Figure 7 and Figure 8As shown in FIG. 1 , the core members 31 are stacked by sequentially inserting the central leg portion 42 into the hollow portion 21 of the bobbin 20. Specifically, as shown in the figure, the core members 31, 31 are inserted into the hollow portion 21 alternately and reversely. For example, in Figure 7 and Figure 8 In the figure, when the direction from left to right on the paper is defined as the first direction and the direction from right to left opposite to the first direction is defined as the second direction, first, with respect to the first core member 31, the I-type core 50 is directed upward, and the legs 41, 42, 41 of the E-type core 40 are directed toward the bobbin 20 side from the first direction, so that the central leg 42 is inserted into the hollow portion 21, and the central leg 42 is inserted into the hollow portion 21. Next, with respect to the second core member 31, the I-type core 50 is directed downward, and the legs 41, 42, 41 of the E-type core 40 are directed toward the bobbin 20 side from the second direction, so that the central leg 42 is inserted into the hollow portion 21, and the legs 41, 42, 41 of the first core member 31 overlap with the legs 41, 42, 41 of the second core member 31. In addition, hereinafter, the core member inserted from the first direction is referred to as the first core member 31a, and the core member inserted from the second direction is referred to as the second core member 31b. Then, the first core member 31a is inserted from the first direction again, and the second core member 31b is inserted from the second direction, so that Fig. 9 As shown, the first core member 31 a and the second core member 31 b are stacked in a state where the leg portions 41 and 42 ( 42 not shown) overlap each other (stacking step).

[0083] Thus, the current transformer 10 can be obtained. However, in this state, the first core member 31a and the second core member 31b are not fixed yet, but remain inserted into the hollow portion 21. Therefore, in order to prevent the stacked first core member 31a and the second core member 31b from being scattered, as shown in FIG. Fig. 9 As shown, it is preferred to align the end edges to integrate the first core members 31a and the second core members 31b (integration step). The integration can be performed by welding, for example. Fig. 9 As shown in the figure 36. Welding 36 can be exemplified by laser welding or resistance welding. In addition, integration can also be performed by riveting or bonding. When welding 36 is performed, it is preferred to Figure 6 The above is implemented in the region 46 with low magnetic flux density described in the above.

[0084] As described above, in the current transformer 10 in which the first core members 31a and the second core members 31b are integrated, a gap 60 is formed between the front ends of the legs 41, 42, 41 of the first core member 31a and the inner end edge of the I-type core 50 of the second core member 31b. In addition, a gap 60 is formed between the front ends of the legs 41, 42, 41 of the second core member 31b and the inner end edge of the I-type core 50 of the first core member 31a. The gap 60 can be adjusted by pressing the first core member 31a and the second core member 31b from the first direction and the second direction (gap adjustment step).

[0085] like Fig. 9 and Fig.10 As shown by the middle arrow, the gap 60 can be adjusted by pressing the first core component 31a and the second core component 31b from the first direction and the second direction, respectively, with reference to the output voltage characteristics of the current transformer 10. Thus, even if there is a deviation in the material magnetic properties of the core or a temperature deviation in the annealing process of the core, the output voltage of the current transformer 10 can be adjusted with high precision by adjusting the gap 60, and the tolerance can be reduced as much as possible. According to the present invention, the tolerance can be less than ±1% in the case of an effective value, preferably less than ±0.5%. For example, the gap 60 can be 0.1 mm to 0.4 mm, preferably about 0.2 mm.

[0086] Then, after the adjustment of the gap 60 is completed, as shown in FIG. Figure 1 and Fig.11 As shown, the first core component 31a and the second core component 31b are integrated by welding 37 or the like at the position where the legs 41 and 41 located on the outside overlap (integration step). Thus, the first core component 31a and the second core component 31b are integrated, and the width of the gap 60 after temporary adjustment can be prevented from changing. In addition, since the first core components 31a and the second core components 31b are integrated first, the welding 37 for integrating the first core component 31a and the second core component 31b only needs one or more spot welding. Therefore, the magnetic properties of the core components 31a and 31b are hardly affected by the welding 37.

[0087] The current transformer 10 of the present invention can be integrated with the first core member 31a and the second core member 31b without using varnish, adhesive, or resin, and is not affected by the thermal expansion / contraction thereof. Therefore, the current transformer 10 having excellent temperature characteristics can be provided.

[0088] In the above description, after the first core members 31a and the second core members 31b are integrated, the gap 60 is adjusted and the first core member 31a and the second core member 31b are integrated. Fig. 9 The gap 60 is adjusted without integrating the first core members 31a and the second core members 31b. In this case, after the gap 60 is adjusted, Fig.12 As shown, the wire welding 38 may be performed at the position where the leg portions 41, 41 located on the outside of the first core member 31a and the second core member 31b overlap. This simplifies the manufacturing process of the current transformer 10.

[0089] In the present invention, if Fig.11 and Fig.12 As shown, the first core member 31a and the second core member 31b are welded 37 and 38 in the substantially central portion of the leg portion 41 of the E-type core 40. Therefore, the length of linear expansion is suppressed to half, and the first core member 31a and the second core member 31b linearly expand in the same direction starting from the welded portions 37 and 38, so that the gap 60 hardly changes. In addition, Fig.11 The welding parts 36 and 37, Fig.12 The welded portions 38 are formed substantially parallel to the lamination direction of the first core member 31 a and the second core member 31 b , so that the linear expansion of the welded portions due to heat does not affect the size of the gap 60 .

[0090] In the above description, the first core members 31a are stacked with the I-type core 50 facing upward and the second core members 31b facing downward, but for example Fig.13 As shown, if the first core member 31a and the second core member 31b are paired, the front and back may be alternated, or may be changed randomly for each of a plurality of pairs. Thus, the burrs 73 and the collapse 70 (see FIG. 1 ) in the case of manufacturing the E-type core 40 and the I-type core 50 by stamping and blanking can be reduced. Fig.14 ) etc. to equalize the thickness deviation caused by

[0091] Fig.14 (a) and Fig.14 (b) is an enlarged view of the butt joint between the front ends of the legs 41, 42, 41 of the E-type core 40 of the first core member 31a and the inner end surface of the I-type core 50 of the second core member 31b. Fig.14As shown, the end faces of the E-type iron core 40 and the I-type iron core 50 have rounded and smooth avalanches 70, shear surfaces 71 with rib-like marks formed in the plate thickness direction by shearing, fracture surfaces 72 with sharp unevenness as if the material has been peeled off, and sawtooth-like burrs 73 protruding from the end faces in the punching direction. Then, as Fig.14 As shown in (a), the E-type iron core 40 and the I-type iron core 50 are arranged so that the shear surfaces 71, 71 are opposite to each other and the fracture surfaces 72, 72 are opposite to each other. When the fracture surfaces 72, 72 are butted against each other, the fracture surfaces 72, 72 are in contact with each other, but a gap remains between the shear surfaces 71, 71. Therefore, the adjustment width of the gap becomes smaller, and the adjustment width of the output voltage also becomes narrower. Therefore, when the E-type iron core 40 and the I-type iron core 50 are butted against each other, as shown in FIG. Fig.14 As shown in (b), the E-type core 40 and the I-type core 50 are preferably arranged so that the shear surface 71 and the fracture surface 72 face each other. This can reduce the gap 60, thereby increasing the adjustment width of the gap 60 and the adjustment width of the output voltage, making adjustment easier.

[0092] <Different Implementation Methods>

[0093] In the above embodiment, the first core member 31a and the second core member 31b are inserted into the hollow portion 21 one by one. Fig.15 As shown, a first core component block 32a in which the first core components 31a are pre-stacked and integrated by welding or riveting, and a second core component block 32b in which the second core components 31b are pre-stacked and integrated by welding or riveting are respectively manufactured, and when they are mounted on the bobbin 20, the leg 41 of the second core component 31b is inserted between the legs 41, 41 of the first core components 31a, 31a, and the leg 41 of the first core component 31a is inserted between the legs 41, 41 of the second core components 31b, 31b. Thus, the core components 31a and 31b do not need to be stacked one by one on the bobbin 20, so that the manufacturing process can be simplified as much as possible.

[0094] The current transformer 10 obtained as described above can be housed in a housing 80 , for example, and used as a current transformer module 12 . Fig.16 is an exploded perspective view of the current transformer 10 and the housing 80 accommodating the current transformer. Fig.17 is a three-dimensional diagram of the current transformer 10, Fig.18 1 is a longitudinal sectional view of the current transformer 10. As shown in the figure, the housing 80 is formed by an upper housing 81 and a lower housing 85. The upper housing 81 is a frame-shaped body with an opening on the lower surface for accommodating the iron core 30 and the bobbin 20, and the lower housing 85 can be a plate-shaped body for placing the bobbin 20 and blocking the lower surface of the upper housing 81. Fig.19 FIG. 8 shows a bottom view of the upper housing 81. Fig. 20A top view of the lower housing 85 is shown in FIG.

[0095] In the lower case 85, insertion holes 86a, 86b are formed through which the terminal wires 26a, 26a of the primary side coil 26 and the terminal wires 27a, 27a of the secondary side coil 27 extend, respectively. Fig.16 and Fig.18 As shown in FIG. 1 , the terminal wires 26a and 26b are inserted into the insertion holes 86a and 86b, and the bobbin 20 is positioned in the lower case 85 and inserted into the upper case 81, thereby obtaining the current transformer module 12. Fig.17 The resulting current transformer module 12 is shown in FIG.

[0096] In addition, after the current transformer module 12 is manufactured, the output voltage characteristics can be measured respectively, such as Fig.17 The obtained characteristic data is printed or sealed in the upper housing 81 as a data matrix 89. Therefore, when the current transformer module 12 is used in an AC device, the data matrix 89 can be read, and the characteristic adjustment can be performed in the control based on the corresponding characteristic data. In this way, a more accurate output voltage characteristic can be achieved.

[0097] In the combination of the current transformer 10 and the housing 80, the current transformer module 12 is required to be miniaturized. In order to achieve the miniaturization of the current transformer module 12, the current transformer 10 is required to be miniaturized. In order to miniaturize the current transformer 10, it is desirable to reduce the protruding height of the upper insulating wall 22 and the lower insulating wall 24, which insulate the primary side coil 26 and the secondary side coil 27 provided on the bobbin 20 (such as Fig.16 , Fig.18 However, in order to achieve insulation between the primary coil 26 and the secondary coil 27, it is necessary to ensure an insulation creepage distance (the shortest distance measured along the surface of the insulator).

[0098] Therefore, in the present invention, if Fig.16 and Fig.18 As shown, the bobbin 20 forms an upper recess 23 between the upper insulating wall 22 disposed between the primary coil 26 and the secondary coil 27 and the primary coil 26. On the other hand, in the upper housing 81, as shown in FIG. Fig.18 and Fig.19 As shown, an upper convex portion 83 that fits into the upper concave portion 23 is formed.

[0099] Then, when the current transformer 10 is housed in the upper housing 81, the upper protrusion 83 is fitted into the upper recess 23 to form an insulating wall, which can extend the insulation creepage distance of the primary coil 26 and the secondary coil 27. In addition, by fitting the upper protrusion 83 into the upper recess 23, the bobbin 20 can be positioned in the upper housing 81.

[0100] Furthermore, a depression along the outer shape of the primary coil 26 is formed inside the upper surface of the upper case 81 as a stopper 82 for suppressing the primary coil 26 from falling off. The stopper 82 prevents the primary coil 26 from falling off when the current transformer module 12 is mounted on a printed wiring board or the like.

[0101] In addition, if Fig.18 As shown, the bobbin 20 forms a lower recess 25 between the lower insulating wall 24 disposed between the primary coil 26 and the secondary coil 27 and the primary coil 26. Fig.16 , Fig.18 and Fig.19 As shown, a lower convex portion 87 that fits into the lower recess 25 is formed in the lower case 85 .

[0102] Then, when the current transformer 10 is placed on the lower case 85 , the lower protrusion 87 fits into the lower recess 25 to form an insulating wall, thereby extending the insulation creepage distance between the primary coil 26 and the secondary coil 27 .

[0103] Thus, the insulating walls 22 and 24 of the bobbin 20 can be reduced while ensuring the creepage distance of the primary coil 26 and the secondary coil 27, thereby miniaturizing the current transformer 10 and the current transformer module 12. In addition, by fitting the lower protrusion 87 into the lower recess 25, the bobbin 20 can be positioned in the lower case 85.

[0104] In addition, preferably, a step portion 88 supporting the lower surface of the bobbin 20 is provided in the lower shell 85. When the bobbin 20 abuts against the lower shell 85, the lower surface of the bobbin 20 abuts against the step portion 88, and the bobbin 20 is held in the shell 80 without tilting.

[0105] Furthermore, in the current transformer 10 of the present invention, the gap 60 is adjusted while referring to the output voltage characteristics. Therefore, due to the width of the gap 60, the iron core 30 has a play in the long dimension direction of the leg portion 41 relative to the bobbin 20, and sometimes slides in the through direction of the hollow portion 21 and becomes loose. Therefore, it is desirable to position the iron core 30 relative to the bobbin 20 in the current transformer module 12.

[0106] As described above, the bobbin 20 is positioned in the housing 80 by the engagement of the upper recess 23 with the upper convex portion 83 and the engagement of the lower recess 25 with the lower convex portion 87. Therefore, if the core 30 can also be positioned relative to the housing 80, the core 30 and the bobbin 20 can also be positioned relative to each other. Fig.18As shown, a structure capable of positioning the core 30 relative to the housing 80 is adopted. Specifically, when the upper housing 81 positions the bobbin 20, one inner surface 84 abuts against the core 30, and the connecting portion 43 of the E-type core 40 and the I-type core 50 are clamped by the bobbin 20 and the inner surface 84 of the upper housing 81. Thus, in the current transformer module 12 of the present invention, since the core 30 is pressed against the bobbin 20, the core 30 and the bobbin 20 can be positioned, and the occurrence of looseness can be suppressed.

[0107] The above description is used to illustrate the present invention and should not be understood as limiting the invention or limiting the scope of the invention described in the claims. In addition, the various structures of the present invention are not limited to the above embodiments, and various modifications can be made within the technical scope described in the claims.

[0108] Example

[0109] exist Fig.21 The output voltage measurement circuit 90 shown in the figure is equipped with a current transformer 10, and the output voltage characteristics are measured. The output voltage measurement circuit 90 connects the primary side coil 26 of the current transformer 10 to an AC power source 92 connected in series with an ammeter 91, and the secondary side coil 27 is connected in parallel with a resistor 93 to a voltmeter 94. As an example of the invention, Figure 1 The current transformer 10 is shown.

[0110] In addition, for comparison, Figure 1 The current transformer 100 having only the E-type core 40 and omitting the I-type core is manufactured as Comparative Example 1 ( Fig. 22 ), the patent document 1 Figure 6 The current transformer 101 in which the E-type iron core 40 and the I-type iron core 50 are integrated with varnish or the like is manufactured as a comparative example 2 ( Fig.23 ), and then, the E-type iron core 40 is overlapped longitudinally to form a block, and the I-type iron core 50 is also overlapped longitudinally to form a block, and the block 103 of the E-type iron core 40 is butted with the block 104 of the I-type iron core 50 and fixed with varnish, and the current transformer 102 is made as Comparative Example 3 ( Fig.24 ).

[0111] Example 1

[0112] The current transformer 10 of the invention example was tested at -25°C, 25°C, and 80°C temperatures, with the input current (A) changed and the output voltage (V) measured. Fig.25 See Fig.25It can be seen that in each temperature environment, the output voltage of the current transformer 10 of the present invention has a proportional relationship with the input current and has excellent temperature characteristics. This is because the current transformer 10 is formed by inserting the E-type iron core 40 and the I-type iron core 50 that are previously integrated by riveting or welding from the first direction and the second direction and integrating them by welding, so that varnish, adhesive, resin, etc. that are easily affected by thermal expansion / heat contraction are not used for the integration of the iron core 30, thereby reducing the influence of thermal expansion / heat contraction as much as possible.

[0113] Example 2

[0114] For the current transformer 10 ( Figure 1 )、Comparative Example 1 current transformer 100 ( Fig. 22 )、Comparative Example 2 current transformer 101 ( Fig.23 ), the output voltage characteristics were measured in a 25°C temperature environment. The results are as follows Fig.26 See Fig.26 , the output voltage of the invention example has a basically linear proportional relationship with respect to the input current. However, the output voltage of Comparative Example 1 decreases on the high current side. In addition, in Comparative Example 1, since the front end of the leg of the E-type core 40 is open, the leakage flux between the legs becomes larger, and there is also a problem of faster magnetic saturation. In order to eliminate this, Comparative Example 1 also needs to increase the size of the core. Comparative Example 2 needs to use varnish to fix the E-type core 40 and the I-type core 50. It can be seen that due to these misalignments, the output voltage decreases especially on the high current side.

[0115] Example 3

[0116] For the current transformer 102 of Comparative Example 3 ( Fig.24 ), similarly to Example 1, the output voltage characteristics were measured at -25°C, 25°C, and 80°C. The results are as follows Fig. 27 See Fig. 27 It can be seen that the output voltage characteristic of the current transformer 102 of Comparative Example 3 deviates due to temperature changes. This is because the varnish of the fixed core 30 thermally expands / contracts due to temperature changes, the core 30 linearly expands, and the gap between the block 103 of the E-type core 40 and the block 104 of the I-type core 50 changes.

[0117] According to the above-described first to third embodiments, it can be seen that the temperature characteristics of the current transformer 10 of the inventive example are extremely excellent compared to the comparative example.

[0118] Description of Reference Numerals

[0119] 10Current transformer

[0120] 11Current transformer module

[0121] 20 spools

[0122] 21 Hollow

[0123] 30 core

[0124] 31 Core components

[0125] 31a First core member

[0126] 31b Second core member

[0127] 40 E-type core

[0128] 50 I-type core

[0129] 60 Clearance

[0130] 80 shell.

Claims

1. A current transformer having: A resin bobbin having a through hollow portion and having a primary coil and a secondary coil wound thereon; and The iron core is formed of electromagnetic steel sheets, in, The iron core is formed by inserting the central legs of the E-type iron core into the hollow part of the bobbin alternately and reversely from a first direction and a second direction opposite to the first direction, and stacking them. The iron core component for the current transformer has the E-type iron core and the I-type iron core, and the I-type iron core is overlapped on the connecting part of the E-type iron core to form an integrated whole. The E-type iron core is formed by stamping and punching an electromagnetic steel sheet and has three legs extending approximately in parallel and the connecting part connecting the ends of the legs. The I-type iron core is formed by stamping and punching an electromagnetic steel sheet and has approximately the same length as the connecting part. The end surface of the E-type iron core and the end surface of the I-type iron core facing each other are arranged so as to have opposite punching directions.

2. The current transformer according to claim 1, in, The end faces of the E-type iron core and the I-type iron core are processed by punching and blanking to form a rounded and smooth collapse at the corner, a shear surface with rib-like marks in the plate thickness direction by shearing, a fracture surface with sharp unevenness as if the material is peeled off, and a sawtooth burr protruding from the end face in the punching direction. The E-type iron core and the I-type iron core are arranged so that the shear surface and the fracture surface face each other.

3. The current transformer according to claim 1, in, The current transformer core members stacked in the hollow portion of the bobbin are integrated with each other.

4. The current transformer according to claim 2, in, The current transformer core members stacked in the hollow portion of the bobbin are integrated with each other.

5. The current transformer according to any one of claims 1 to 4, in, The current transformer core members inserted into the hollow portion of the bobbin from the first direction are integrated with each other in a stacked state. The current transformer core members inserted into the hollow portion of the bobbin from the second direction are integrated with each other in a stacked state.

6. A method for manufacturing a current transformer, in, include: A step of preparing a core component for a current transformer, wherein the core component for a current transformer is an E-type core and an I-type core, wherein the I-type core is integrated by overlapping the I-type core at a connecting portion of the E-type core, the E-type core being formed by punching and blanking an electromagnetic steel sheet and having three legs extending substantially parallel to each other and the connecting portion connecting ends of the legs, and the I-type core being formed by punching and blanking an electromagnetic steel sheet and having substantially the same length as the connecting portion; a bobbin preparation step of preparing a resin bobbin having a through hollow portion and wound with a primary coil and a secondary coil; A stacking step, inserting the leg portion at the center of the E-type core of the current transformer core component into the hollow portion of the bobbin alternately from a first direction and a second direction opposite to the first direction and in reverse directions, and stacking the E-type core and the opposite I-type core in a manner in which the punching directions are opposite; a gap adjustment step of pressing the stacked current transformer core components from the first direction and / or the second direction, and adjusting, with reference to output voltage characteristics, a gap formed between a front end of the leg portion of the E-type core of the current transformer core component inserted from the first direction and an end edge of the I-type core of the current transformer core component inserted from the second direction, and a gap formed between a front end of the leg portion of the E-type core of the current transformer core component inserted from the second direction and an end edge of the I-type core of the current transformer core component inserted from the first direction; as well as The integration step integrates the stacked current transformers into a core component.

Images