Current detector

Abstract

To provide a current detector capable of fixing a circuit board in a space-saving manner without interfering with a magnetic core or the like.SOLUTION: A current detector has a case 1 for housing a circuit board 4 having one or more fixing holes and to be fixed with an adhesive 12. The case 1 has: a protrusion 5 passing through the fixing hole from a predetermined direction; and a pedestal 6 holding the circuit board 4 by a circuit board holding surface from the predetermined direction in the vicinity of the protrusion 5. The protrusion 5 has: a first cavity part 11 spaced in the predetermined direction near the center; a second cavity part 15 interposed between itself and the pedestal 6 and having a predetermined depth T in the predetermined direction from the circuit board holding surface; and a third cavity part leading from the first cavity part 11 to the second cavity part 15. An adhesive 12 is injected from the first cavity part 11 and flows into the second cavity part 15 through the third cavity part.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a current detector that detects a current by disposing a magnetic detection element such as a Hall element in a gap of a magnetic core. [Background technology]

[0002] Conventional current detectors (current sensors) are composed of a case made of insulating resin, a magnetic collecting core, a magnetic detection element such as a Hall element, and a circuit board on which the magnetic detection element is mounted. To prevent the circuit board on which the detection element is mounted from moving, the circuit board is insulated and fixed using a case with a boss (board base) for screwing (see, for example, Patent Document 1).

[0003] Regarding a method for fixing a circuit board (wiring board) to a case (sensor housing), a method is known in which an adhesive is applied to a base (board adhesive pin) for supporting the circuit board provided on the case side to adhesively fix the circuit board to the case (see, for example, Patent Document 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication 2022-170629 Figure 2 [Patent Document 2] Patent Publication 2019-164080 Figure 13 Summary of the Invention [Problem to be solved by the invention]

[0005] In conventional current detectors, when fixing a circuit board with a tapping screw as in Patent Document 1, it is necessary to provide a boss for fastening the screw around the magnetic core to prevent interference between the screw and the magnetic core, which results in a problem of large circuit board and case.

[0006] Furthermore, when the surface of the circuit board and the case side base are adhesively fixed as in Patent Document 2, the adhesive and the electronic components come close to each other when the circuit board is miniaturized, so there is a risk that the adhesive will adhere to the electronic components. If a current detector (current sensor) is used in an environment where the temperature is high (or low) or where high and low temperatures are repeatedly changed, there is a risk that the adhesive will crack the electronic components if it is applied to the electronic components due to the thermal expansion and contraction of the adhesive.

[0007] The present invention has been made to solve the above-mentioned problems, and makes it possible to fix a small-sized circuit board with high reliability. [Means for solving the problem]

[0008] The current detector of the present invention has a case that houses a circuit board having one or more fixing holes and fixes it with an adhesive, and the case has a protrusion that penetrates the fixing hole from a predetermined direction and a base portion around the protrusion that holds the circuit board from a predetermined direction on the circuit board holding surface, and the protrusion has a first cavity opening in a predetermined direction near the center, a second cavity between the base portion and of a predetermined depth in a predetermined direction from the circuit board holding surface, and a third cavity connecting the first cavity to the second cavity, and the adhesive is injected from the first cavity and flows into the second cavity via the third cavity. Effect of the Invention

[0009] According to the present invention, in order to adhesively fix the circuit board to the case, it is only necessary to provide a space for a hollow portion (second hollow portion) for storing adhesive at a predetermined depth from the circuit board holding surface around the vicinity of the protrusion for positioning the circuit board, thereby making it possible to miniaturize the current detector. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a perspective view of a current detector according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is an exploded perspective view of the current detector according to the first embodiment of the present invention. [Diagram 3]1 is a top view of a current detector in accordance with a first embodiment of the present invention. [Figure 4] FIG. 4 is a cross-sectional view taken along line AA in FIG. [Diagram 5] FIG. 2 is an explanatory diagram of adhesive injection into the current detector in the first embodiment of the present invention. [Figure 6] 3 is a detailed perspective cross-sectional view of an adhesive injection section of the current detector in accordance with the first embodiment of the present invention. FIG. [Figure 7] 6A to 6C are diagrams illustrating another shape of the positioning boss in the first embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

[0012] Embodiment 1 Fig. 1 is a perspective view of a current detector 100 in accordance with the first embodiment of the present invention, and Fig. 2 is an exploded perspective view of the current detector 100 in accordance with the first embodiment of the present invention. Fig. 3 is a top view of the current detector 100 in accordance with the first embodiment of the present invention, and Fig. 4 is a cross-sectional view taken along line AA in Fig. 3. As shown in Fig. 2, the current detector 100 has a case 1 made of insulating resin, a magnetic flux collecting core 2, a magnetic detection element 3 such as a Hall element, a circuit board 4 on which the magnetic detection element 3 and the like are mounted, and an adhesive 12 (shown in Fig. 4) that fixes the circuit board 4 to the case 1.

[0013] Here, the case 1 is composed of a positioning boss 5 which is a protrusion for assembling the circuit board 4 with high precision, a board base 6 which is a base for supporting the circuit board 4, a magnetic detection element storage hole 7 which stores the magnetic detection element 3, a core storage section 8 which stores the magnetic collection core 2, and a through hole 20 which allows a conductor (not shown) through which the current to be measured flows to pass.

[0014] The magnetic flux collecting core 2 is made of, for example, silicon steel plate or permalloy, and is formed into a C-shape or U-shape by stacking or rolling the plate material, and collects the magnetic flux generated by the current to be measured. At the center of the upper part of the magnetic flux collecting core 2 in the figure, there is a gap 19 for inserting the magnetic detection element 3 that detects the collected magnetic flux. By storing the magnetic flux collecting core 2 in the core storage section 8 of the case 1, the gap 19 of the magnetic flux collecting core 1 is positioned to sandwich the magnetic detection element storage hole 7 of the case 1.

[0015] Circuit board 4 is mounted with magnetic detection element 3 and electronic components (not shown) such as a capacitor, and has holes 9 for fixing the board at positions where positioning bosses 5 are inserted. Circuit board 4 is positioned by inserting positioning bosses 5 of case 1 into holes 9 for fixing the board, and after it comes into contact with board base 6, it is adhesively fixed to case 1. These positioning bosses 5 and board base 6 are provided in multiple places depending on the size of circuit board 4.

[0016] As shown in Fig. 3, positioning boss 5 has an outer shape that contacts board fixing hole 9 of circuit board 4, has a first cavity 11 in the center toward the front in the figure, and has a cylindrical shape with slit-shaped third cavities 10 at two locations on the left and right in the figure. As shown in Fig. 4, positioning boss 5 has a bottom surface 16 formed by carving a part of board base 6 of case 1 into a circular shape with a predetermined depth T (for example, 1.6 mm in the downward direction in the figure, which is equivalent to the thickness of circuit board 4), and has a second cavity 15 between the outside of positioning boss 5 and the circular hole of the predetermined depth T in board base 6.

[0017] Here, a method for bonding the circuit board 4 and the case 1 will be described. Fig. 5 is an explanatory diagram of the injection of adhesive 12 from nozzle 13 of a dispenser for applying adhesive, and Fig. 6 is a detailed perspective cross-sectional view of the injection part of adhesive 12. In Fig. 5, 13 is the nozzle of the dispenser used to apply adhesive 12, and in Fig. 6, 14 is the fixing hole gap between the wall surface of hole 9 for fixing the circuit board 4 and positioning boss 5, and 18 is the contact surface between the illustrated lower surface of the circuit board 4 and second cavity 15.

[0018] 5 and 6, a dispenser nozzle 13 used to apply adhesive 12 is inserted into first cavity 11 of positioning boss 5, and adhesive 12 discharged from dispenser nozzle 13 accumulates in first cavity 11 and also flows out of third cavity 10 of positioning boss 5 to accumulate in second cavity 15 and fixing hole gap 14. Adhesive 12 comes into contact with circuit board 4 at fixing hole gap 14 and contact surface 18 of second cavity 15, thereby bonding and fixing circuit board 4 to case 1.

[0019] The shape of the positioning boss 5 may have any shape as long as it has a function of positioning the circuit board 4 and a function of allowing the adhesive 12 to flow from the first cavity 11 to the second cavity 15 or the fixing hole gap 14, and may be not only a shape having a slit shape with a sectorial opening in a part of the hollow cylinder shown in Fig. 3, but also a shape in which one or more square poles 17 contact the board fixing hole 9 of the circuit board 4 as shown in Fig. 7. The third cavity 10 does not have to be slit-shaped, and may be a hole shape leading from the first cavity 11 to the second cavity 15. Fig. 7 shows another shape of the positioning boss 5 of the current detector 100 in the first embodiment of the present invention, Fig. 7(a) is a top view, and Fig. 7(b) is a perspective view.

[0020] In the current detector 100 configured in this manner, the circuit board 4 is positioned by fitting the positioning boss 5 into the hole 9 for fixing the board provided in the circuit board 4, and fixing the circuit board 4 only requires the space of the second cavity 15 of a predetermined depth T below the circuit board 4 for allowing the adhesive 12 to flow in, so that the circuit board 4 can be fixed in a space-saving manner without interfering with the magnetic core 2, etc.

[0021] In the case of adhesively fixing the circuit board 4, it is possible to apply the adhesive 12 to the board base 6 as in Patent Document 2, but if the amount of adhesive 12 applied is large, the adhesive 12 may overflow when the circuit board 4 and the board base 6 are attached to each other, and the adhesive 12 may adhere to the components mounted on the circuit board 4. When the current detector is used in an environment where high temperature (or low temperature) or high and low temperatures are repeatedly changed, the thermal expansion and contraction of the adhesive 12 may cause cracks in the mounted components to which the adhesive 12 is applied, and the adhesive work is a careful work to prevent the adhesive from coming into contact with the mounted components, which requires skill and a corresponding amount of work time. In the present embodiment 1, the adhesive 12 is poured after the circuit board 4 is positioned, and the poured adhesive 12 accumulates in the first cavity 11, the third cavity 10, the fixing hole gap 14, and the second cavity 15 of the positioning boss 5, making it possible to prevent the adhesive 12 from adhering to the mounted components on the circuit board 4, and since there is no need to perform careful work, the work time can be shortened. [Explanation of symbols]

[0022] 1 case 2 Magnetic core 3. Magnetic sensing element 4 Circuit Board 5 Positioning boss (protrusion) 6 Board base (base part) 7 Magnetic detection element storage hole 8 Core storage section 9 Holes for fixing the board 10. The Third Cavity 11 First Cavity 12. Adhesive 13 Dispenser nozzle 14 Fixed hole cavity 15 Second Cavity 16. Carved Surface 17 square prism 18 Contact surface 19. Gap 20 through holes T specified depth

Claims

1. A current detector having a case for receiving a circuit board having one or more fixing holes and fixing the circuit board with an adhesive, the case has a protrusion penetrating the fixing hole from a predetermined direction A, and a base portion around the vicinity of the protrusion for holding the circuit board from the direction A on a circuit board holding surface, The protrusion has a first cavity near the center of the protrusion in the A direction, the protrusion has a second cavity between the protrusion and the base, the second cavity having a predetermined depth in the A direction from the circuit board holding surface, the protrusion has a third cavity portion communicating with the first cavity portion and the second cavity portion, A current detector, characterized in that the adhesive is injected from the first cavity and flows into the second cavity via the third cavity.

2. A current detector having a case for receiving a circuit board having one or more fixing holes and fixing the circuit board with an adhesive, the case has a protrusion penetrating the fixing hole from a predetermined direction A, and a base portion around the vicinity of the protrusion for holding the circuit board from the direction A on a circuit board holding surface, The protrusion has a first cavity near the center of the protrusion in the A direction, the protrusion has a second cavity between the protrusion and the base, the second cavity having a predetermined depth in the A direction from the circuit board holding surface, The protrusion has a fixing hole gap between itself and a wall surface of the fixing hole, the protrusion has a third cavity portion communicating from the first cavity portion to the second cavity portion or the fixing hole gap portion, A current detector characterized in that the adhesive is injected from the first cavity and flows through the third cavity into the second cavity or the fixing hole gap.

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