Current detector

Abstract

To provide a technique to ensure a long creeping distance.SOLUTION: In a current sensor 100, a magnetic core 110, an inner covering part 120, and an outer covering part 130 are integrally formed by two-stage insert molding. As a result of the insert being fixed in a mold during molding, an inner opening 123 is formed in the inner covering part 120, and an outer opening 134 is formed in the outer covering part 130, however, since the outer opening 134 is separated from the inner opening 123 and does not overlap with the inner opening 123, the magnetic core 110 is not exposed from the outer opening 134. Therefore, the current sensor 100 can ensure a longer creepage distance than current sensors in which magnetic cores are exposed from openings formed on wall parts of case bodies. In addition, since a circuit board on which magnetic sensing elements are mounted is positioned with respect to the inner covering part 120 molded integrally with the magnetic core 110, the positional accuracy of the magnetic sensing elements relative to the magnetic core 110 can be further improved.SELECTED DRAWING: Figure 10

Description

[Technical field]

[0001] The present invention relates to a current detector. [Background technology]

[0002] In a current detector, in order to obtain insulation between a primary conductor through which a current to be detected flows and a core made of a magnetic material, a case made of an insulating material is provided around the core. For example, a current sensor in which a magnetic core and a molded resin are integrally molded by insert molding is known (for example, see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2010-203910 A Summary of the Invention [Problem to be solved by the invention]

[0004] In current detectors, in accordance with standards such as UL and IEC, a certain insulation distance (creepage distance and clearance distance) corresponding to the input voltage must be secured between the primary conductive part and the secondary conductive part. In insert molding, the core inserted in the mold is pressed and fixed, and then molding resin is injected to form the case, so an opening is formed in the case where the core is fixed. As a result, in a current detector having a case obtained by simple insert molding, the core is exposed from the opening, so there is a limit to how far the creepage distance can be ensured, and it is difficult to guarantee high voltage resistance.

[0005] Therefore, an object of the present invention is to provide a technique for ensuring a long creepage distance. [Means for solving the problem]

[0006] In order to solve the above problems, the present invention employs the following current detector. Note that the words in parentheses below are merely examples, and the present invention is not limited thereto.

[0007] That is, the current detector of the present invention comprises a magnetic core in which a gap is formed in the middle of a ring-shaped magnetic path that converges a magnetic field generated by the conduction of a current to be detected, an inner covering portion covering the surface of the magnetic core and having a first inner opening formed corresponding to the gap and a plurality of second inner openings different from the first inner opening, and an outer covering portion covering the surface of the inner covering portion and penetrating into the second inner opening, and having a first outer opening formed corresponding to the first inner opening and a plurality of second outer openings different from the first outer opening formed in a position that does not overlap with the second inner opening.

[0008] In the current detector of this aspect, the case body is composed of an inner covering part and an outer covering part. As a result of the insert being fixed by a mold during molding of the case body, the inner covering part and the outer covering part each have an opening (a second inner opening, a second outer opening) formed at the fixing location of the insert, but since the second outer opening of the outer covering part is formed at a position that does not overlap with the second inner opening of the inner covering part, the magnetic core is not exposed from the second outer opening.

[0009] Therefore, according to the current detector of this aspect, a longer creepage distance can be ensured by the distance from the second outer opening to the second inner opening, compared to a case in which the magnetic core is exposed from an opening formed in the case body due to the above-mentioned molding process. Also, by covering the surface of the magnetic core with the inner covering and covering the surface of the inner covering with the outer covering, the magnetic core, the inner covering, and the outer covering are in close contact with each other, so that the accuracy of the position of the core relative to the case body can be improved.

[0010] More preferably, in the current detector of the above aspect, the inner covering part has a plurality of protrusions on a wall surface of an inner circumferential wall surrounding a hole penetrating the center of the inner covering part, and the outer covering part has an outer inner circumferential wall surrounding the hole penetrating the center of the outer covering part that is wedged into the protrusions. Also, the outer covering part does not have a second outer opening formed in an outer circumferential wall located radially of the hole penetrating the center of the outer covering part. Alternatively, the outer covering part has an outer inner circumferential wall that is continuous and flush with the protrusions.

[0011] When molding the outer covering part, the inner covering part covering the surface of the magnetic core is fixed by a mold. In the current detector of this aspect, since a plurality of protrusions are provided on the wall surface of the inner inner peripheral wall (the inner peripheral surface of the inner covering part), the position of the central hole in the radial direction (= directions perpendicular to the central axis (Y axis) of the hole; X direction and Z direction) can be fixed by inserting a part of the mold along these protrusions. This allows the outer covering part to be molded by a mold with a simple structure, which can reduce the cost of the mold and the number of second outer openings formed in the outer covering part.

[0012] More preferably, in the current detector according to any of the above aspects, the current detector further includes a circuit board on which the magnetic sensing element is mounted and which is disposed in the gap, the inner covering portion having a portion for determining the position of the circuit board inside the first inner opening, and the outer covering portion has the first outer opening larger than the first inner opening and surrounds the first inner opening.

[0013] In the current detector of this aspect, when the circuit board is installed in the gap, the positioning of the circuit board is determined by the inner coating which covers and adheres closely to the magnetic core, and the outer coating is not involved in the positioning, which can further increase the positional accuracy of the magnetic sensing element relative to the magnetic core and stabilize the performance of the current sensor. Effect of the Invention

[0014] As described above, according to the present invention, a long creepage distance can be ensured. [Brief description of the drawings]

[0015] [Figure 1] 1 is a perspective view of a current sensor 100 according to an embodiment. [Diagram 2] 3A to 3C are diagrams illustrating a manufacturing process of the current sensor 100. [Diagram 3] FIG. 13 is a diagram (1 / 3) showing the inner covering portion 120. [Figure 4] FIG. 2 is a view (2 / 3) showing the inner covering portion 120. [Diagram 5] FIG. 3 is a view (3 / 3) showing the inner covering portion 120. [Figure 6] FIG. 12 is a diagram (1 / 2) showing the outer covering portion 130. [Figure 7] FIG. 2 is a view (2 / 2) showing the outer covering portion 130. [Figure 8] 2 is a cross-sectional view showing the positional relationship between a core 110, an inner covering portion 120, and an outer covering portion 130. FIG. [Figure 9] FIG. 2 is an exploded perspective view of the current sensor 100. [Figure 10] 3 is a diagram illustrating an insulation distance in the current sensor 100. FIG. [Figure 11] FIG. 2 is a diagram illustrating a current sensor 200' as a first comparative example. [Figure 12] FIG. 11 is a diagram illustrating a current sensor 300' as a second comparative example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] [Configuration of current sensor] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Fig. 1 shows a current sensor 100 according to an embodiment. Fig. 1(A) is a perspective view from the front side, and Fig. 1(B) is a perspective view from the back side. For ease of explanation, in all the figures, the up-down direction, left-right direction, and front-rear direction in Fig. 1 are defined as the up-down direction, left-right direction, and front-rear direction of each component, and the shape and structure are explained. Furthermore, the up-down direction, left-right direction, and front-rear direction of the component may be referred to as the Z direction, the X direction, and the Y direction, respectively.

[0017] Current sensor 100 is configured by housing a core and a circuit board in case body 102. Case body 102 is made of resin, has a substantially annular shape, and has a through hole 104 penetrating the center. In addition, a connector 106 is provided on the upper part of current sensor 100. For current sensor 100, a primary conductor (e.g., a bus bar) through which a current to be detected flows is inserted into through hole 104, and an external connector having a connection terminal connected to an external device or circuit board is inserted into connector 106.

[0018] To facilitate understanding of the structure of the current sensor 100, a manufacturing process for the current sensor 100 will be briefly described with reference to FIG.

[0019] 2A, the core 110 is C-shaped when viewed from the front, with a gap 112 between the opposing end faces. When the core 110 is viewed including the gap 112, the core 110 has a substantially rectangular ring shape. The core 110 is made of a magnetic material (e.g., silicon steel).

[0020] First, in the first molding step, the core 110 is inserted and fixed in a mold, and then molten resin is injected to mold the inner covering part 120 integrally with the core 110 (FIG. 2(B)). Next, in the second molding step, the molded product obtained in the first step, i.e., the inner covering part 120 molded integrally with the core 110, is inserted and fixed in a mold, and then molten resin is injected to mold the outer covering part 130 integrally with the inner covering part 120 (FIG. 2(C)). In this way, the case body 102 is formed by two-step insert molding, and is composed of the inner covering part 120 that covers the surface of the core 110 and the outer covering part 130 that covers the surface of the inner covering part 120.

[0021] Then, the circuit board 140 on which the connector 106 and the magnetic sensing element are mounted is inserted from an opening provided in the upper part of the case body 102 and placed in the gap 112 of the core 110, the circuit board 140 is positioned relative to the inner covering part 120 (FIG. 2(D)), and the circuit board 140 is fixed to the outer covering part 130 with screws 160 (FIG. 2(E)). Finally, the cover part 170 is fitted into the outer covering part 130 (FIG. 2(F)), completing the current sensor 100. The latter assembly process will be described further below with reference to another drawing.

[0022] Next, a description will be given of the shapes and structures of the inner covering part 120 and the outer covering part 130 that constitute the case body 102. For ease of explanation, in the following figures, the inner covering part 120 and the outer covering part 130 are shown not as separate parts but as parts housing the core 110.

[0023] [Inner covering part] 3 to 5 show the inner covering part 120. In FIG. 3, (A) is a perspective view seen from the upper right front, (B) is a perspective view seen from the lower left front, (A) is a plan view, (B) is a bottom view, (C) is a left side view, (A) is a front view, and (B) is an enlarged view of a part of the inner circumferential surface. In these figures, the core 110 exposed from the opening of the inner covering part 120 is darkly shaded so that the opening of the inner covering part 120 can be easily seen. In addition, the back view is substantially the same as the plan view, and the right side view is substantially the same as the left side view, so that the back view and the right side view are omitted.

[0024] 3A and 4A, a large opening 121 is provided in the upper part of the inner covering part 120. The opening 121 is used when a circuit board is installed in the gap 112 of the core 110.

[0025] In the first molding stage, the core 110 inserted in the mold is pressed from the outside in the Y and Z directions, the position of the core 110 in the mold in the Y and Z directions is fixed, and then resin is injected to mold the inner covering part 120, so that an opening is formed at the position pressed by the mold. As a result, in addition to the above-mentioned opening 121 for installing the circuit board, the inner covering part 120 has two small rectangular openings 122 and two small circular openings 123 on each of the front and back faces as shown in Figures 3 and 5 (A), and has four circular openings 123 on the bottom face as shown in Figure 4 (B).

[0026] The positioning of core 110 in the X direction within the mold is performed simultaneously with the positioning in the Z direction by utilizing gap 112 of core 110, and since core 110 is not pressed from the outside in the X direction, no openings are formed on the left and right sides of inner covering portion 120, as shown in Fig. 4(C). By fixing the position of core 110 within the mold in this manner, the number of slide cores constituting the mold can be reduced, the cost of the mold can be reduced, and the number of openings formed in inner covering portion 120 can be reduced.

[0027] A plurality of protrusions are provided on the inner peripheral surface 124 of the inner covering portion 120. In other words, a plurality of protrusions protrude from the inner peripheral wall of the inner covering portion 120. Specifically, as shown in Fig. 3, three rectangular protrusions 125 protruding in a rectangular shape are provided at approximately equal intervals on each of the upper and lower faces of the inner peripheral surface 124, and one cross protrusion 126 protruding in a cross shape is provided on each of the left and right faces. As shown in Fig. 5(A), the protrusions 125, 126 provided on the inner peripheral surface 124 both have flat top surfaces and are the same height.

[0028] In the second stage of molding, a part of the mold MD is inserted along the top surfaces of these protrusions 125, 126. This fixes the position of the inner covering part 120 in the mold in the X and Z directions, so there is no need to press and fix the inner covering part 120 from the outside in the X and Z directions. This allows the mold to have a simple structure, and the mold cost to be reduced. In addition, the number of openings formed in the molded product obtained in the second stage, i.e., the outer covering part 130, can be reduced.

[0029] In the second molding stage, resin for molding the outer covering part 130 is injected from gates GT facing the lower left and upper right parts of the front of the inner covering part 120 fixed to the mold (see (A) in FIG. 5). At this time, the inner covering part 120 may rotate due to the injection pressure of the resin, but the protrusions 125, 126 provided on the inner circumferential surface 124 can reduce the effect of the injection pressure and prevent the inner covering part 120 from rotating.

[0030] More specifically, a plurality of rectangular protrusions 125 are provided on each of the upper and lower surfaces of the inner circumferential surface 124 because there is sufficient space. By arranging a plurality of rectangular protrusions 125 having a certain length at a certain interval, it is possible to prevent the inner covering part 120 from rotating about the X-axis, the Y-axis, and the Z-axis. On the other hand, one cross protrusion 126 is provided on each of the left and right surfaces of the inner circumferential surface 124 because the space is narrow. As shown in FIG. 5B, which shows an enlarged view of the left side of the inner circumferential surface 124, the cross protrusion 126 has a portion 126y that extends in the Y-direction by a certain length and a portion 126z that extends in the Z-direction by a certain length. The presence of the portion 126y prevents the inner covering part 120 from rotating about the Y-axis, while the presence of the portion 126z prevents the inner covering part 120 from rotating about the Z-axis.

[0031] In the illustrated example, of the three rectangular protrusions 125 arranged side by side on each of the upper and lower faces of the inner circumferential surface 124, the one sandwiched between them is larger than the two on either side, but the size of each rectangular protrusion 125 can be changed as appropriate. Also, a plurality of rectangular protrusions 125 are arranged on each of the upper and lower faces of the inner circumferential surface 124, and one cross protrusion 126 is arranged on each of the left and right faces, but the shape and number of the protrusions arranged can be changed as appropriate depending on the size of each face that constitutes the inner circumferential surface.

[0032] [Outer covering part] 6 and 7 show the outer covering part 130. Fig. 6(A) is a perspective view seen from the upper right front, Fig. 6(B) is a front view, Fig. 6(C) is a rear view, Fig. 7(A) is a plan view, Fig. 7(B) is a bottom view, Fig. 7(C) is a left side view, and Fig. 7(D) is a right side view. In these figures, in order to make the opening of the outer covering part 130 easy to see, the inner covering part 120 exposed from the opening of the outer covering part 130 is lightly shaded, and the core 110 is darkly shaded.

[0033] As shown in Fig. 6(A) and Fig. 7(A), an opening 131 for installing a circuit board, which is slightly larger than the opening 121 of the inner covering part 120, is provided in the upper part of the outer covering part 130, and the peripheral part of the opening 121 in the inner covering part 120 is exposed from the opening 131. In addition, two fastening parts 132 are provided at positions sandwiching the opening 121 from the front and rear. Each fastening part 132 is connected to a protection part 133 extending upward from the center of the upper end of each of the front and rear walls of the outer covering part 130. As shown in Fig. 7(C) and (D), each fastening part 132 has a fastening hole 132a penetrating in the X direction. The fastening hole 132a is used to screw the circuit board.

[0034] In the second molding stage, inner covering part 120 integrated with core 110 is inserted into a mold, and as described above, a part of the mold is inserted while aligning it with multiple protrusions 125, 126 provided on inner peripheral surface 124 to fix the X-direction and Z-direction positions of inner covering part 120 within the mold (in other words, the radial position of the hole penetrating the center of inner covering part 120 = the position in the direction perpendicular to the central axis of the hole), and further, inner covering part 120 is pressed in the Y direction to fix the Y-direction position of inner covering part 120 within the mold, and then resin is injected to mold outer covering part 130, so that an opening is formed at the position pressed by the mold.

[0035] As a result, the outer covering portion 130 has four small circular openings 134 on its front surface, as shown in Figures 6 (A) and (B), and also has four circular openings 134 on its back surface, as shown in Figure 6 (C). However, as shown in Figures 7 (B) to (D), the outer covering portion 130 does not have any circular openings 134 on its bottom surface, left side surface, or right side surface (in other words, on the outer peripheral wall located radially of the hole penetrating the center of the outer covering portion 130).

[0036] 6 and 7(B), the multiple rectangular openings 122 and the circular openings 123 of the inner covering portion 120 are all filled and covered by the outer covering portion 130. In other words, the multiple circular openings 134 in the outer covering portion 130 do not overlap the multiple rectangular openings 122 and the circular openings 123 of the inner covering portion 120, but are formed at positions away from these openings 122, 123, and the outer covering portion 130 bites into and adheres to the openings 122, 123 provided in the inner covering portion 120. This indicates that when the position of the inner covering portion 120 is fixed in the mold in the second molding stage, the inner covering portion 120 is pressed down at a position away from the openings 122, 123.

[0037] 6(A), the protrusions 125, 126 of the inner covering portion 120 are embedded in the inner circumferential wall 135 of the outer covering portion 130, and only the top surfaces of the protrusions 125, 126 are exposed from the outer covering portion 130. In other words, the protrusions 125, 126 provided on the inner circumferential surface of the inner covering portion 120 bite into and are in close contact with the inner circumferential wall 135 of the outer covering portion 130.

[0038] 8 shows a cross-sectional view of the positional relationship between the core 110, the inner covering portion 120, and the outer covering portion 130. FIG. 8(A) shows the VIII in FIG. A -VIII A FIG. 8B is a cross-sectional view taken along line VIII in FIG. B -VIII B FIG.

[0039] As shown in Fig. 8A, the projections 125, 126 (protruding from the inner wall 127) provided on the inner peripheral surface 124 of the inner covering part 120 bite into and adhere closely to the inner peripheral wall 135 of the outer covering part 130, and the inner peripheral wall 135 and the projections 125, 126 are connected flush with each other. Also, as shown in Fig. 8A and B, there is no gap between the core 110 and the inner covering part 120, and between the inner covering part 120 and the outer covering part 130. In this way, by forming each part of the case body that houses the core by insert molding, the core and the case body can be adhered closely to each other, and the variation in the position of the core 110 relative to the case body can be reduced.

[0040] [Assembly of components] FIG. 9 is an exploded perspective view of the current sensor 100. As shown in FIG. 9A, an IC 150 (e.g., a Hall IC) having a built-in magnetic sensing element is mounted on a front surface 140a of a circuit board 140, and a connector 106 for receiving an external connector is mounted on a back surface 140b.

[0041] The circuit board 140 is inserted into the gap 112 of the core 110, and positioned by abutting the back surface 140b and side surfaces of the circuit board 140 against the positioning groove 121a in the opening 121 formed in the inner covering part 120. A step is provided between the edge of the opening 121 in the inner covering part 120 and the edge of the opening 131 in the outer covering part 130, so that only the inner covering part 120 is involved in the positioning, and the outer covering part 130 does not interfere. In this way, by positioning the circuit board 140 with respect to the inner covering part 120 molded integrally with the core 110, it is possible to further reduce the variation in the position of the magnetic sensing element with respect to the core 110.

[0042] 9(B), screws 160 are fastened into fastening holes 132a to fix circuit board 140 to outer covering part 130. Finally, cover part 170 is placed on the top of circuit board 140, fitted into protective part 133, and fixed to outer covering part 130.

[0043] [Ensuring creepage distance] 10A and 10B are diagrams illustrating the insulation distance in the current sensor 100. In FIG.

[0044] When a current to be detected flows through a primary conductor (not shown) inserted through through hole 104 of current sensor 100, a magnetic field generated around it is converged to core 110. In current sensor 100, the creepage distance is the shortest distance along the insulator between the primary conductor and core 110, that is, the shortest distance along inner covering 120 and outer covering 130 from through hole 104 to core 110.

[0045] FIG. 10(B) is a cross-sectional view (cross-sectional view along line XX) of the current sensor 100 cut at a position passing through a circular opening 134 (hereinafter, sometimes referred to as the "outer opening 134") that is the opening of the outer covering portion 130 that is closest to the through hole 104, and a circular opening 123 (hereinafter, sometimes referred to as the "inner opening 123") that is the opening of the inner covering portion 120 that is closest to the outer opening 134.

[0046] As described above, the outer opening 134 is formed at a position that does not overlap with the inner opening 123, and therefore there is no portion where the core 110 is directly exposed to the outside. As shown in Fig. 10A, the outer opening 134 is separated from the through hole 104 by a distance L1. Furthermore, when proceeding from the outer opening 134 to the core 110 along the interface between the outer covering portion 130 and the inner covering portion 120, as shown in Fig. 10B, the shortest route is from point a at the outermost end of the outer opening 134 to point d at the innermost end of the inner opening 123 via point b at the innermost end of the outer opening 134 and point c at the outermost end of the inner opening 123.

[0047] Therefore, the sum of the distance L1 from the through hole 104 to the outer opening 134, the depth L2 of the outer opening 134 (the thickness of the outer covering portion 130), the distance L3 from the outer opening 134 to the inner opening 123, and the depth L4 of the inner opening 123 (the thickness of the inner covering portion 120) is the creepage distance CD in the current sensor 100. If the path of the creepage distance CD were shown as a continuous line, it would look like the thick line in Figure 10 (C).

[0048] [Comparison with the first comparative example] FIG. 11 shows a current sensor 200' as a first comparative example. 11A is an enlarged plan view of the lower part of the current sensor 200'. The case body 220' of the current sensor 200' has the same appearance as the case body 102 of the above-mentioned embodiment, but since it is obtained by one insert molding, the core 110' is exposed from each opening 222' formed at the position of pressing by the mold. The distance L1' from the opening 222' to the through hole 204' in the case body 220' is the same as the distance L1 from the outer opening 134 to the through hole 104 in the case body 102. In addition, the thickness L2' of the case body 220' is the same as that of the case body 102, that is, the thickness L2 of the outer covering portion 130 and the thickness L4 of the inner covering portion 120 are added together.

[0049] 11B is a vertical cross-sectional view (cross-sectional view along line XI-XI) of the current sensor 200′ cut through the opening 222′ that is the closest to the through-hole 204′ among the openings of the case body 220′. In the current sensor 200′, the creepage distance CD′ is the sum of the distance L1′ from the through-hole 204′ to the opening 222′ and the depth L2′ of the opening 222′ (the thickness of the case body 220′). As described above, in the current sensor 200′, since the core 110′ is exposed from the opening formed in the case body 220′, it is difficult to ensure a sufficient creepage distance.

[0050] In contrast, in the current sensor 100 of the above-mentioned embodiment, the case body 102 has a two-layer structure in which the inner covering portion 120 and the outer covering portion 130 are integrated, and the outer opening 134 is formed at a position away from the inner opening 123, so that an insulation distance can be ensured that is longer than that of the current sensor 200' of the first comparative example by the distance L3 connecting the outer opening 134 and the inner opening 123.

[0051] [Comparison with the second comparative example] Fig. 12 shows a current sensor 300' as a second comparative example. For ease of explanation, only the core and case body of the current sensor 300' are shown. Fig. 12(A) is an exploded perspective view showing a simplified structure of the case body, and Fig. 12(B) is a cross-sectional view taken along line XII-XII.

[0052] As shown in Fig. 12(A), in the current sensor 300', the case body is composed of a housing section 320' that houses a core 310' and a lid section 330' that covers the housing section 320'. Since there are individual differences in dimensions for any component, a clearance is required in the space for housing the component. Therefore, a space slightly larger than the dimensions of the core 310' is provided inside the housing section 320', and a space slightly larger than the dimensions of the housing section 320' is provided inside the lid section 330'.

[0053] Specifically, as shown in FIG. 12(B), at least eight clearances are provided in the up-down direction inside current sensor 300', and at least four clearances are provided in the front-rear direction. Although not shown, at least eight clearances are also provided in the left-right direction. The presence of such clearances causes variation in the position of the core relative to the case body and variation in the position of the magnetic sensing element relative to the core. In addition to the clearances, current sensor 300' also requires a structure for fixing the components.

[0054] In contrast, in the current sensor 100 of the above-described embodiment, the core 110, the inner covering portion 120, and the outer covering portion 130 are integrally provided, and therefore no clearance or structure for fixing the components is required, which makes it possible to reduce the size of the case body and, in turn, the current sensor 100. In addition, since the core 110 is in close contact with the case body, variation in the position of the core is reduced, and therefore variation in the position of the magnetic sensing element relative to the core 110 can also be reduced, making it possible to stabilize the performance of the current sensor 100.

[0055] The current sensor 100 of the above-described embodiment has the following advantages.

[0056] (1) The case body 102 that houses the core 110 is composed of an inner covering portion 120 and an outer covering portion 130, and the openings 122, 123 (inner openings) formed in the wall of the inner covering portion 120 and the opening 134 (outer opening) formed in the wall of the outer covering portion 130 are separated from each other, and the core 110 is not exposed from the outer opening. Therefore, compared to a case in which the case body is formed by simple insert molding and the core is exposed from an opening formed in the wall of the case body, a longer creepage distance can be secured by the distance from the outer opening to the inner opening, and it is possible to sufficiently secure insulation performance and guarantee high voltage resistance.

[0057] (2) The inner peripheral surface 124 of the inner covering portion 120 is provided with a plurality of rectangular protrusions 125 and cross protrusions 126. When the outer covering portion 130 is integrally molded with the inner covering portion 120, a part of a mold is inserted along these protrusions 125, 126, so that the position of the inner covering portion 120 in the X direction and Z direction within the mold is fixed. Therefore, it is not necessary to press and fix the inner covering portion 120 from the outside in the X direction and Z direction. Therefore, the mold can be simplified in structure, which reduces the cost of the mold and also reduces the number of openings formed in the outer covering portion 130.

[0058] (3) The two-stage insert molding allows the core 110, the inner covering portion 120, and the outer covering portion 130 to be integrally formed and adhered to one another, thereby improving the positional accuracy of the core 110 relative to the case body.

[0059] (4) Since the circuit board 140 on which the magnetic sensing element is mounted is positioned relative to the inner covering portion 120 which is molded integrally with the core 110, the positional accuracy of the magnetic sensing element relative to the core 110 can be further improved, and the performance of the current sensor 100 can be stabilized.

[0060] (5) The two-stage insert molding process integrates the core 110, the inner covering portion 120, and the outer covering portion 130 into a single body and adheres them to one another. This eliminates the need to provide clearances or the like inside the case body, as is the case when the core is housed in a case body consisting of a housing portion and a lid portion that are made separately. This makes it possible to reduce the size of the current sensor 100.

[0061] The present invention is not limited to the above-described embodiment and modified examples, and can be implemented in various ways.

[0062] Although core 110 has a substantially rectangular ring shape when viewed including gap 112, the shape of the core is not limited to this and may be, for example, a substantially circular ring shape or another ring shape. In other words, the core may have any shape as long as a gap is formed in the middle of a ring-shaped magnetic path that converges a magnetic field generated by the conduction of a current to be detected.

[0063] Although the inner covering portion 120 and the outer covering portion 130 are formed from resin, the material of the case body may be any insulating material and is not limited to resin.

[0064] By the two-stage insert molding, the inner covering portion 120 is molded integrally with the core 110, and the outer covering portion 130 is molded integrally with the inner covering portion 120, so that the core 110, the inner covering portion 120 and the outer covering portion 130 are adhered to each other. However, if technically possible, two case bodies having shapes similar to the above-mentioned inner covering portion 120 and outer covering portion 130 may be produced by a method other than insert molding, and the core and these two case bodies may be adhered to each other.

[0065] In addition, the structures illustrated in the embodiments are merely preferred examples, and it goes without saying that the present invention can be suitably implemented by adding various elements to the basic structure or by substituting parts thereof. [Explanation of symbols]

[0066] 100 Current sensor (current detector) 110 Core (Magnetic Core) 112 Gap 120 Inner coating 121 Opening for installing circuit board (first inner opening) 122 Rectangular opening (second inner opening) 123 Circular opening (second inner opening) 124 Inner surface 125 Rectangular protrusion (protrusion) 126 Cruciform process (protrusion) 127 Inner peripheral wall (inner inner peripheral wall) 130 Outer covering part Opening for mounting circuit board (first outer opening) Circular opening (second outer opening) Inner peripheral wall (outer inner peripheral wall)

Claims

1. a magnetic core having a gap formed in the middle of a ring-shaped magnetic path that converges a magnetic field generated by the conduction of a current to be detected; an inner covering portion covering a surface of the magnetic core and having a first inner opening formed in correspondence with the gap and a plurality of second inner openings different from the first inner openings; an outer covering portion including a first outer opening that is formed corresponding to the first inner opening and that is engaged with the second inner opening while covering a surface of the inner covering portion, and a plurality of second outer openings different from the first outer openings that are formed at positions not overlapping with the second inner openings; A current detector comprising:

2. 2. The current detector according to claim 1, The inner covering portion is A plurality of protrusions are provided on the inner peripheral wall surrounding the hole passing through the center thereof, The outer covering portion is A current detector characterized in that an outer inner circumferential wall surrounding a hole passing through the center thereof is bitten into by the protrusion.

3. 3. The current detector according to claim 2, The outer covering portion is A current detector, characterized in that the second outer opening is not formed in an outer peripheral wall located in a radial direction of a hole passing through the center of the current detector.

4. 3. The current detector according to claim 2, The outer covering portion is A current detector characterized in that the outer inner circumferential wall is flush with the protrusion.

5. 5. The current detector according to claim 1, Further comprising a circuit board having a magnetic sensing element mounted thereon and disposed within the gap; The inner covering portion is A current detector comprising: a portion for determining a position of the circuit board on the inside of the first inner opening.

6. 6. The current detector according to claim 5, The outer covering portion is The current detector, wherein the first outer opening is larger than the first inner opening and surrounds the first inner opening.

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