JP5704352B2 - Current sensor - Google Patents

Description

  The present invention relates to a current sensor that detects a current to be measured in a non-contact manner using a magnetosensitive element.

  In a conventional current sensor, members such as a magnetic body and a magnetosensitive element are generally housed in a case and sealed with a sealing material such as a resin.

JP 2005-308526 A

  In the conventional configuration, a case for fixing the member is indispensable, and the cost tends to increase. Another problem is that stress is applied to the magnetic body and the magnetosensitive element by sealing.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a case for fixing a magnetic body and a magnetosensitive element and a current sensor that does not require sealing.

One embodiment of the present invention is a current sensor. The current sensor includes a substrate, a magnetosensitive element mounted on the substrate, and first and second magnetic bodies, a spacer is disposed on one surface of the substrate, and the first and second The magnetic body is fixed to each other by a fixing component in a state where the substrate and the spacer are sandwiched, a ground pattern is exposed on the other surface of the substrate, and one of the first and second magnetic bodies and the ground pattern are Are in contact with each other and electrically connected to each other, and the first and second magnetic bodies are electrically connected to each other by the fixed component .

  The spacer may surround the magnetosensitive element.

  A conductor pattern serving as a path of the current to be measured may be provided on the substrate.

  A bus bar serving as a path of the current to be measured may be held by the spacer or may be integrated.

  A through hole through which the bus bar serving as a path of the current to be measured is inserted may be formed in the spacer.

The spacer may have a divided structure, and a bus bar that serves as a path for the current to be measured may be sandwiched.

  It should be noted that any combination of the above-described constituent elements, and those obtained by converting the expression of the present invention between methods and systems are also effective as aspects of the present invention.

  According to the present invention, a case for fixing a magnetic body and a magnetosensitive element and a current sensor that does not require sealing can be realized.

1 is an exploded perspective view of a current sensor according to Embodiment 1 of the present invention. The perspective view after the assembly of the same current sensor. The lower perspective view of the state which decomposed | disassembled the 2nd magnetic body 5 of the same current sensor. The front view of the same current sensor. The perspective view of the current sensor which concerns on Embodiment 2 of this invention. The disassembled perspective view of the current sensor which concerns on Embodiment 3 of this invention. The perspective view after the assembly of the same current sensor. The perspective view of the spacer 3 of the same current sensor. The side view of the spacer 3. FIG. The side view of the same current sensor. The disassembled perspective view of the current sensor which concerns on Embodiment 4 of this invention. The perspective view of the assembly process 1 of the same current sensor. The perspective view of the assembly process 2 of the same current sensor. The perspective view after the assembly of the same current sensor. The disassembled perspective view of the current sensor which concerns on Embodiment 5 of this invention. The perspective view of the assembly process of the same current sensor. The perspective view after the assembly of the same current sensor.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In addition, the same code | symbol is attached | subjected to the same or equivalent component, member, etc. which are shown by each drawing, and the overlapping description is abbreviate | omitted suitably. In addition, the embodiments do not limit the invention but are exemplifications, and all features and combinations thereof described in the embodiments are not necessarily essential to the invention.

  1 is an exploded perspective view of a current sensor according to Embodiment 1 of the present invention. FIG. 2 is an upper perspective view of the current sensor after assembly. FIG. 3 is a lower perspective view of the current sensor in a state where the second magnetic body 5 is disassembled. FIG. 4 is a front view of the current sensor. As shown in these drawings, the current sensor of the present embodiment includes a substrate 1, a magnetosensitive element 2, a spacer 3, a first magnetic body 4, and a second magnetic body 5.

  The magnetosensitive element 2 is, for example, a Hall IC and is mounted on one surface of the substrate 1. The spacer 3 is made of, for example, an insulating resin, and is disposed on one surface of the substrate 1 (the mounting surface of the magnetosensitive element 2). In the present embodiment, the spacer 3 has a frame shape or a cylindrical shape and surrounds the periphery of the magnetosensitive element 2. The first magnetic body 4 and the second magnetic body 5 are formed by bending a high permeability magnetic material (for example, a silicon steel plate) into a U-shaped cross section, and the tip surfaces (both edges) are gaps 7. To form a rectangular tube shape having two slits (gap 7) on the outer peripheral surface as a whole. The magnetic body insertion hole 8 of the substrate 1 is provided for passing or positioning the tip of the second magnetic body 5.

  The substrate 1 is an insulator, and surface-mounting terminal portions 9 are respectively formed on edges of the substrate 1 facing each other. A conductor pattern 15 (thick copper pattern) passing between the terminal portions 9 is provided on one surface of the substrate 1 to form a path for the current to be measured. A magnetic field generated by the current to be measured is applied to the magnetosensitive element 2, and the current to be measured is measured by the output signal of the magnetosensitive element 2. Note that a resist (not shown) is interposed between the conductor pattern 15 and the magnetic sensing element 2 to ensure insulation. In addition to the magnetosensitive element 2, various electronic components are mounted on the substrate 1 as necessary, and a required wiring pattern is formed accordingly.

  The first magnetic body 4 and the second magnetic body 5 are fixed to each other by a fixing component 6 such as a rivet in a state where the substrate 1 and the spacer 3 are sandwiched. That is, the pair of fixing parts 6 includes a pair of fastening holes 11 of the first magnetic body 4, a pair of fastening holes 12 of the spacer 3, a pair of fastening holes 13 of the substrate 1, and a pair of second magnetic bodies 5. The tip is caulked through the fastening hole 14, and the first magnetic body 4, the spacer 3, the substrate 1, and the second magnetic body 5 are fastened and integrated. The fixing part 6 is a fastening part having conductivity, and, for example, a combination of a bolt and a nut may be used in addition to the rivet.

  As shown in FIG. 3, the ground pattern 10 is exposed on the other surface of the substrate 1 (the surface on which the magnetosensitive element 2 is not mounted). As shown in FIG. 4, the ground pattern 10 and the second magnetic body 5 are in contact with each other and electrically connected. Further, the first magnetic body 4 and the second magnetic body 5 are electrically connected to each other by a fixing component 6.

  According to the present embodiment, the following effects can be achieved.

(1) Since the case for fixing the board | substrate 1, the magnetic sensitive element 2, the 1st magnetic body 4, and the 2nd magnetic body 5 is unnecessary, member cost can be reduced compared with the former.

(2) The assembly process of the current sensor only requires mounting of the component on the substrate 1 by reflow, for example, and mutual fixing of the first magnetic body 4 and the second magnetic body 5 by the fixing component 6. The number of assembly steps can be reduced as compared with the case of sealing with resin casting and resin casting or insert molding.

(3) There is a problem that stress is applied to the magnetosensitive element 2, the first magnetic body 4, and the second magnetic body 5 in the case of being housed and sealed as in the conventional case. Then, since sealing of those members and insert molding are unnecessary, stress can be reduced.

(4) Since the first magnetic body 4 and the second magnetic body 5 are electrically connected to the ground pattern 10, the eddy current can be reduced as compared with the case where they are electrically floating, and noise. Is unlikely to occur. In addition, it is possible to prevent stray capacitance from being generated by the C coupling of the first magnetic body 4 and the second magnetic body 5 and noise from being added to the sensor output.

(5) Since the spacer 3 surrounds the magnetic sensing element 2, a dustproof effect on the magnetic sensing element 2 can be obtained.

(6) The position of the magnetosensitive element 2 is generated when the first magnetic body 4 is magnetized by the measured current and when the second magnetic body 5 is magnetized by the measured current. Therefore, the hysteresis of the detection output of the current sensor can in principle be zero (or near zero). That is, it is possible to improve the zero ampere measurement accuracy of the current sensor.

(7) Since the magnetosensitive element 2 is arranged inside the first magnetic body 4 and the second magnetic body 5 facing each other, the conventional structure in which the magnetosensitive element is arranged in the gap of the ring-shaped magnetic core; In comparison, the disturbance magnetic field flowing into the magnetosensitive element 2 is reduced, and disturbance noise resistance is improved.

  FIG. 5 is a perspective view of a current sensor according to Embodiment 2 of the present invention. In this current sensor, the gap 7 is eliminated and the front end surfaces (both edges) of the first magnetic body 4 and the second magnetic body 5 are in contact with each other as compared with the first embodiment shown in FIG. Are different, and are otherwise identical. By adjusting the size of the spacer 3, the gap 7 can be eliminated as in the present embodiment. The present embodiment can achieve the same effects as those of the first embodiment.

  FIG. 6 is an exploded perspective view of a current sensor according to Embodiment 3 of the present invention. FIG. 7 is a perspective view after assembly of the current sensor. FIG. 8 is a perspective view of the spacer 3 of the current sensor. FIG. 9 is a side view of the spacer 3. FIG. 10 is a side view of the current sensor. In the present embodiment, unlike the first embodiment, the bus bar 16 passing through the spacer 3 forms a path of the current to be measured. The bus bar 16 is insert-molded into the spacer 3 while being bent into a U-shape. The bus bar 16 may be flat and may be held by the spacer 3 without using insert molding. The spacer 3 has a rectangular parallelepiped shape with rounded corners, and an element receiving recess 17 is provided on the surface facing the substrate 1. The magnetosensitive element 2 mounted on the substrate 1 is located in the element accommodating recess 17 (FIG. 10). In addition to the magnetosensitive element 2, an electronic component 18 is mounted on the substrate 1. One of the front end surfaces (both edges) of the first magnetic body 4 and the second magnetic body 5 is opposed to the outside of the substrate 1, and the other is opposed in the vicinity of the magnetic material insertion hole 8 of the substrate 1. Although not shown, in the present embodiment as well, the first magnetic body 4 and the second magnetic body 4 are exposed by exposing the ground pattern and contacting the second magnetic body 5 as in the first embodiment. The body 5 can be at ground potential. Other points of the present embodiment are the same as those of the first embodiment. The present embodiment can achieve the same effects as those of the first embodiment.

  FIG. 11 is an exploded perspective view of a current sensor according to Embodiment 4 of the present invention. FIG. 12 is a perspective view of assembly process 1 of the current sensor. FIG. 13 is a perspective view of assembly process 2 of the current sensor. FIG. 14 is a perspective view after assembly of the current sensor. This current sensor is different from that of the third embodiment shown in FIGS. 6 and 7, and the bus bar 16 has a flat plate shape and is separate from the spacer 3. The bus bar 16 is attached so as to form a path of a current to be measured through attachment holes 22 provided at both ends. The spacer 3 has a substantially rectangular parallelepiped shape and has a bus bar insertion hole 24 through which the bus bar 16 is inserted. The fixing component 6 penetrates a pair of fastening holes 19 formed in the bus bar 16 together with other fastening holes 11 to 14. A lower portion of the bus bar insertion hole 24 is a base portion 25 that comes into contact with the bus bar 16, and extends in front of and behind the bus bar insertion hole 24. The base portion 25 is provided with a pair of fastening holes 21, and the bus bar 16 is provided with a pair of fastening holes 20 corresponding to the fastening holes 21 of the base portion 25. The pair of fastening holes 20 of the bus bar 16 and the pair of fastening holes 21 of the base portion 25 are fastened to each other by a pair of fixing parts 23 (fastening parts), and the bus bar 16 and the spacer 3 are fixed to each other. The fixing part 23 may be a rivet or a combination of a bolt and a nut. Other points of the present embodiment are the same as those of the third embodiment. The present embodiment can achieve the same effects as those of the first embodiment.

  FIG. 15 is an exploded perspective view of a current sensor according to Embodiment 5 of the present invention. FIG. 16 is a perspective view of the assembly process of the current sensor. FIG. 17 is a perspective view of the current sensor after assembly. This current sensor is different from that of the fourth embodiment shown in FIGS. 11 to 14 in that the spacer 3 has a divided structure of an upper spacer 3a and a lower spacer 3b and sandwiches the bus bar 16. Matches in other respects. Both the upper spacer 3a and the lower spacer 3b are U-shaped in cross section, and sandwich and hold the bus bar 16 while being fastened by the fixing component 6. For this reason, unlike Embodiment 4, the bus bar 16 does not need to be riveted separately to the spacer 3. The present embodiment can achieve the same effects as those of the first embodiment.

  The present invention has been described above by taking the embodiment as an example. However, it is understood by those skilled in the art that various modifications can be made to each component and each processing process of the embodiment within the scope of the claims. By the way. Hereinafter, modifications will be described.

  The magnetosensitive element 2 is not limited to a Hall IC, and may be a magnetoresistive element (MR element). The principle of current detection is not limited to the magnetic proportional type, but may be a magnetic balance type. In the third to fifth embodiments, the gap 7 may be eliminated as in the second embodiment.

DESCRIPTION OF SYMBOLS 1 Board | substrate, 2 Magnetosensitive element, 3 Spacer, 4 1st magnetic body, 5 2nd magnetic body, 6 Fixed component, 7 Gap, 8 Magnetic body insertion hole, 9 Terminal part, 10 Ground pattern, 11-14 fastening Hole (through hole), 15 conductor pattern, 16 bus bar, 17 element receiving recess, 18 electronic component, 19 to 21 fastening hole, 22 mounting hole, 23 fixing component, 24 bus bar insertion hole, 25 base portion

Claims (6)

A substrate, a magnetosensitive element mounted on the substrate, and first and second magnetic bodies, a spacer is disposed on one surface of the substrate, and the first and second magnetic bodies are the substrate And the spacer are fixed to each other by a fixing component , a ground pattern is exposed on the other surface of the substrate, and one of the first and second magnetic bodies and the ground pattern are in contact with each other The current sensor is electrically connected, and the first and second magnetic bodies are electrically connected to each other by the fixed component . The current sensor according to claim 1, wherein the spacer surrounds the magnetosensitive element. Current sensor according to claim 1 or 2 conductor pattern serving as the path of the current to be measured is provided on the substrate. The current sensor according to claim 1 or 2 , wherein a bus bar serving as a path of a current to be measured is held by or integrated with the spacer. Current sensor according to claim 1 or 2 through holes for inserting the bus bar serving as a path for the current to be measured is formed on the spacer. Current sensor according to claim 1 or 2, wherein the spacer is sandwiched bus bar serving as a path of a electric current to be measured is divided structure.

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