JP2014092478A - Current sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a current sensor which is capable of miniaturizing a whole device, while taking a countermeasure against ESD.SOLUTION: A current sensor (1) includes an inner case (7) including a substrate fixing projection (73) for fixing an insulating substrate (2), an upper magnetic shield (9) including a plurality of leg parts (93) formed by bending a part of a side surface part and a discharge part (94) provided on the extension of at least one or more leg parts (93), and the insulating substrate (2) including a fixing hole through which the substrate fixing projection (73) is inserted and a ground electrode (22) provided in a position facing the discharge part (94). It is arranged so that the substrate fixing projection (73) of the inner case (7) is inserted through the fixing hole of the insulating substrate (2), to position the insulating substrate (2), the leg parts (93) of the upper magnetic shield (9) come into contact with the top end of the side wall (72) of the inner case (7), and the discharge part (94) faces the ground electrode (22) of the insulating substrate (2).

Description

  The present invention relates to a current sensor capable of calculating a current value based on a magnetic field generated by a current to be measured.

  In recent years, in order to control and monitor various devices, current sensors that are attached to various devices and measure currents flowing through the various devices are generally used. As this type of current sensor, a current sensor of a method using a magnetoelectric conversion element (magnetic detection element) such as a magnetoresistive effect element or a Hall element that senses a magnetic field generated from a current to be measured flowing in a current path is well known. Yes. As an example of such a current sensor, a nonmagnetic case contains a hall element mounted on a circuit board, and a bus bar is inserted, and a magnetic shield is attached from above and below so as to cover the nonmagnetic case and magnetically shielded. Has been proposed (see, for example, Patent Document 1).

JP 2010-14477 A

  However, since the structure described above does not have a structure for releasing the static electricity charged in the magnetic shield body, ESD (Electro-Static Discharge) occurs between the magnetic shield and the circuit board, and the current flows. It may cause malfunction of the sensor. For this reason, in the structure mentioned above, it is necessary to thicken a nonmagnetic case as a countermeasure against ESD, and there exists a problem that size reduction of a current sensor is difficult.

  The present invention has been made in view of this point, and an object of the present invention is to provide a current sensor that can downsize the entire apparatus while taking ESD countermeasures.

  The current sensor of the present invention includes an insulating substrate, a magnetoelectric conversion element provided on the insulating substrate, an insulating inner case on which the insulating substrate is placed, a current path fixed to the inner case, A metal upper magnetic shield and a lower magnetic shield that cover the inner case from above and below, and the inner case has an insertion portion for inserting the current path and a substrate for fixing the insulating substrate. The upper magnetic shield includes a bottom surface provided with a fixing protrusion and a plurality of side walls, and the upper magnetic shield includes a top surface portion, a plurality of side surface portions, and a plurality of leg portions provided by bending a part of the side surface portion. And the insulating substrate has a fixing hole through which the substrate fixing protrusion is inserted, and the substrate fixing protrusion of the inner case is inserted into the fixing hole of the insulating substrate. The insulating substrate is positioned on the inner case. The upper magnetic shield is positioned on the inner case by installing the plurality of legs of the upper magnetic shield at the upper ends of the plurality of side walls of the insulating inner case; and The upper magnetic shield is provided with a discharge portion on at least one extension line of the plurality of legs, and the insulating substrate has a ground electrode provided at a position facing the discharge portion. And

  According to the above current sensor, the discharge part of the upper magnetic shield is disposed so as to be in contact with the ground electrode of the insulating substrate or with a small space therebetween, so that when the static electricity is generated, the discharge part is As a result, it is possible to discharge static electricity to the ground electrode and prevent electric discharge from other parts of the upper magnetic shield toward the electronic component. Therefore, it is possible to take ESD countermeasures without increasing the thickness of the inner case on which the insulating substrate is placed. it can. Therefore, it is possible to provide a current sensor that can downsize the entire apparatus while taking ESD countermeasures.

  Further, according to the current sensor, the insulating substrate is fixed by inserting the substrate fixing protrusion of the inner case into the fixing hole of the insulating substrate, and the leg portion of the upper magnetic shield is in contact with the upper end of the side wall of the inner case. Since the upper magnetic shield is fixed by this, the insulating substrate and the upper magnetic shield are respectively fixed to the inner case which is the same member, so that the positional accuracy of the upper magnetic shield relative to the insulating substrate can be increased. It is possible to set the interval between the insulating substrate and the upper magnetic shield with high accuracy. Therefore, the interval between the discharge part and the ground electrode can be shortened, and the discharge from the discharge part can be efficiently performed.

  In the current sensor, in the upper magnetic shield, the leg portions are provided at both end portions of the opposing side surface portions, and the inner case protrudes upward from the upper end portion on each of the opposing side walls. It is preferable that an upper magnetic shield fixing protrusion is provided, and the upper magnetic shield fixing protrusion is in contact with a side surface portion of the leg portion. In this case, since the upper magnetic shield fixing protrusion comes into contact with the side surface portion of the leg portion, the positional accuracy of the upper magnetic shield with respect to the inner case can be increased.

  The current sensor further includes an outer case on which the inner case and the lower magnetic shield are placed, and the outer case is provided with a pair of outer ribs protruding inward on each of the opposing side walls. The outer ribs may contact both end portions of the side surface of the lower magnetic shield. In this case, since the outer rib contacts the both end portions of the side surface portion of the lower magnetic shield, the positional accuracy of the lower magnetic shield with respect to the outer case can be increased.

  Further, in the current sensor, the outer case is provided with a plurality of inner ribs protruding inward on each of the opposing side walls, and the inner rib contacts the outer surface of the side surface portion of the lower magnetic shield. May be. In this case, since the inner rib contacts the outer surface of the side surface portion of the lower magnetic shield, it is possible to increase the positional accuracy of the lower magnetic shield with respect to the outer case.

  Furthermore, in the above current sensor, the outer case is provided with a plurality of first case fixing holes on the bottom surface, and the inner case is provided with a plurality of case fixing protrusions protruding downward from the bottom. The case fixing protrusion may be inserted into the first case fixing hole. In this case, since the case fixing projection is inserted into the first case fixing hole, the positional accuracy of the inner case with respect to the outer case can be increased.

  Furthermore, in the current sensor, the outer case is provided with a plurality of rectangular second case fixing holes on the bottom surface, and the inner case extends downward from the side wall, and has a tip portion. A hook leg having a hook may be provided, and the hook leg may be inserted into the second case fixing hole. In this case, since the hook leg is inserted into the second case fixing hole, the positional accuracy in the vertical direction of the inner case relative to the outer case can be increased.

  Furthermore, in the current sensor, the inner case is provided with a plurality of lower magnetic shield pressing protrusions protruding downward from the bottom surface, and the lower magnetic shield pressing member is provided on the bottom surface of the lower magnetic shield. The protrusion may contact. In this case, since the lower magnetic shield pressing projection comes into contact with the bottom surface portion of the lower magnetic shield, the positional accuracy of the lower magnetic shield in the vertical direction with respect to the inner case can be increased.

  Further, in the current sensor, the upper magnetic shield is provided with a cable through hole, and a cable passing through the cable through hole is electrically connected to a wiring pattern provided on the insulating substrate via a connector. It may be connected. In this case, since the cable penetrating the cable through hole is electrically connected to the wiring pattern provided on the insulating substrate via the connector, the current sensor can be electrically connected to an external circuit. it can.

  Further, in the current sensor, the inner case is provided with an upper magnetic shield fixing rib on each of the opposing side walls, and the upper magnetic shield is provided with a slit on each of the opposing side surfaces. The upper magnetic shield fixing rib may be disposed in the slit. In this case, since the upper magnetic shield fixing rib is disposed in the slit of the upper magnetic shield, the positional accuracy of the upper magnetic shield with respect to the inner case can be increased.

  The current sensor further includes a cover that covers an upper surface of the outer case, and the cover includes a top surface portion, an upper magnetic shield pressing protrusion that protrudes downward from the top surface portion, and a lower side from the outer edge of the top surface portion. A first extension piece provided with a cover pressing hole, and the outer case is provided with a cover pressing protrusion protruding outward from a side wall, and the upper magnetic The upper magnetic shield pressing projection may contact the top surface portion of the shield, and the cover pressing hole and the cover pressing projection may be snap-coupled. In this case, the upper magnetic shield presser protrusion comes into contact with the top surface of the upper magnetic shield, and the cover presser hole and the cover presser protrusion are mechanically joined by a snap fit. In addition, the upper magnetic shield can be prevented from floating.

  Further, in the current sensor, the cover is provided with a second extending piece provided with a first cover fixing rib, extending downward from an orthogonal outer edge of the top surface portion, In the outer case, a first cover fixing slit may be provided on the side wall, and the first cover fixing rib may be disposed in the first cover fixing slit. In this case, since the first cover fixing rib is disposed in the first cover fixing slit, the positional accuracy of the cover with respect to the outer case can be increased.

  According to the present invention, the entire apparatus can be reduced in size while taking ESD countermeasures.

It is the disassembled perspective view which showed the current sensor which concerns on one embodiment of this invention from the upper side. It is the disassembled perspective view which showed the said current sensor from the downward side. It is a top view of the outer case which comprises the said current sensor. It is the perspective view which showed the state which assembled the said current sensor from the upper side. It is AA arrow sectional drawing of the current sensor shown in FIG. It is a perspective view at the time of removing an outer case and a cover from the current sensor shown in FIG. It is the perspective view which showed the current sensor shown in FIG. 5 from the back side. It is a perspective view at the time of removing an upper magnetic shield from the current sensor shown in FIG.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is an exploded perspective view showing a current sensor according to an embodiment of the present invention from above. FIG. 2 is an exploded perspective view showing the current sensor according to the embodiment of the present invention from the lower side. In the following, for convenience of explanation, the lower left direction shown in FIG. 1 is called the front side of the current sensor 1, the upper right direction shown in FIG. 1 is called the rear side of the current sensor 1, and the upper left direction shown in FIG. The lower right direction shown in FIG. 1 is called the right side of the current sensor 1.

  As shown in FIGS. 1 and 2, the current sensor 1 is electrically connected to a wiring pattern provided on the insulating substrate 2 via an insulating substrate 2, a magnetoelectric conversion element 3 mounted on the insulating substrate 2, and a connector 4. The cable 5 to be connected, the inner case 7 through which the current path 6 is inserted and the insulating substrate 2 is fixed, and a pair of magnetic shields (the lower magnetic shield 8 and the upper magnetic shield) covering the inner case 7 from above and below 9), and an outer case 10 and a cover 11 that accommodate these members. The current sensor 1 is provided with a discharge portion 94 in the upper magnetic shield 9 so that when static electricity is generated, current flows from the discharge portion 94 to the ground electrode 22 on the insulating substrate 2 to take ESD countermeasures. is there.

  The insulating substrate 2 is composed of a generally well-known printed wiring board. For example, a metal foil such as copper (Cu) is patterned on a glass-containing epoxy resin base substrate to form a wiring (not shown). A pattern is formed. The insulating substrate 2 is provided in a generally rectangular shape, and a plurality (four in the present embodiment) of through holes 21 are provided in the vicinity of the four corners. The through hole 21 can be used as a fixing hole into which a projection 73 of the inner case described later is inserted. A ground electrode 22 is provided on a part of the outer edge of the insulating substrate 2.

  The magnetoelectric conversion element 3 is an element that detects a magnetic field generated when a current flows through the current path 6. For example, a magnetic detection element using a giant magnetoresistance effect (also referred to as a GMR (Giant Magneto Resistive) element). Can be used. In the current sensor 1, one magnetoelectric conversion element 3 is mounted on the insulating substrate 2 so that the lead terminals are soldered to the wiring pattern of the insulating substrate 2 and face the current path 6.

  The cable 5 is configured by bundling a plurality of electric wires, and the tip portion thereof is connected to the connector 4 and the connector 5a. The cable 5 is electrically connected to the wiring pattern of the insulating substrate 2 through the connector 4. With this configuration, the current sensor 1 can be electrically connected to an external circuit. In addition, the cable 5 has a connector 4 installed on the insulating substrate 2 in advance, and an electric wire connected to the connector 5a when the current sensor 1 is assembled is assembled to the connector 4 so that the wiring pattern of the insulating substrate 2 is electrically connected. Can be connected.

  The current path 6 is made of a material having good conductivity, such as copper (Cu), and is generally linearly provided. Through holes 61 are provided at both ends of the current path 6. The current path 6 is connected to the current path to be measured by, for example, attaching bolts and nuts to the through holes 61.

  The inner case 7 is formed by molding, for example, an insulating resin material, and is provided in a box shape that opens upward. The inner case 7 includes a bottom portion 71 having a rectangular shape in a top view, a side wall 72 provided orthogonal to the bottom portion 71, a protrusion 73 provided to protrude upward from the bottom portion 71, and a lower side from the bottom portion 71. And protrusions 74 and 75 (see FIG. 2) provided so as to protrude from the surface.

  The bottom 71 has a thickness and is provided with an insertion portion 76 through which a part of the current path 6 is inserted. The insertion portion 76 is provided so as to penetrate the bottom portion 71. The current path 6 is embedded in the insertion portion 76 by, for example, insert molding.

  At the lower ends of the pair of side walls 72 facing in the left-right direction, hook legs 77 extending from the side walls 72 downward and having hooks 77a at the tips are provided. The hook leg 77 is inserted into a through hole 103b of the outer case 10 described later. In addition, a projection 78 that slightly protrudes upward from the side wall 72 is provided at the upper end portion of the pair of side walls 72 provided with the hook legs 77. The protrusion 78 can be used as an upper magnetic shield fixing protrusion for positioning the upper magnetic shield 9 by contacting a leg portion 93 of the upper magnetic shield 9 described later.

  A pair of side walls 72 opposed in the front-rear direction are provided with ribs 79 that protrude slightly outward from the side walls 72. The rib 79 is provided at the upper end of the side wall 72 in the front side wall 72, and is provided at the lower end of the side wall 72 in the rear side wall 72 (not shown in FIGS. 1 and 2, see FIG. 7). . The rib 79 can be used as an upper magnetic shield fixing rib that is inserted into a slit 96 of the upper magnetic shield 9 described later to position the upper magnetic shield 9.

  A plurality of projections 73 (four in the present embodiment) are provided near the four corners of the bottom 71. The protrusion 73 includes a protrusion lower part 73a having a generally truncated cone shape and a protrusion upper part 73b having a generally cylindrical shape connected to the protrusion lower part 73a. The protrusion 73 is inserted into the through hole 21 of the insulating substrate 2 and can be used as a substrate fixing protrusion for positioning and fixing the insulating substrate 2.

  The protrusion 73 has a protrusion upper part 73 b that is thinner than the protrusion lower part 73 a, and the protrusion upper part 73 b is inserted into the through hole 21 of the insulating substrate 2, but the protrusion lower part 73 a is inserted into the through hole 21 of the insulating substrate 2. The size is not configured. That is, when the protrusion 73 is inserted into the through-hole 21 of the insulating substrate 2, the lower surface of the insulating substrate 2 is brought into contact with the upper surface of the protrusion lower portion 73a so as to be positioned and fixed. With this configuration, in the current sensor 1, it is possible to increase the positional accuracy between the insulating substrate 2 and the upper magnetic shield 9 described later. Note that the protrusion upper portion 73 b inserted into the through hole 21 of the insulating substrate 2 is deformed by heating and is in contact with the upper surface of the insulating substrate 2.

  The protrusions 74 have a substantially cylindrical shape, and a plurality of (two in the present embodiment) are provided on the lower surface of the bottom 71 and in the vicinity of the center position of the sides facing each other in the front-rear direction. The protrusion 74 can be used as a case fixing protrusion for positioning the inner case 7 and the outer case 10 through a through hole 103a of the outer case 10 described later.

  The protrusion 75 has a generally circular shape, and is provided so as to protrude slightly downward from the lower surface of the bottom 71. A plurality (four in the present embodiment) of protrusions 75 are provided in the vicinity of the center position of each side on the lower surface of the bottom portion 71. The protrusion 75 can be used as a lower magnetic shield pressing protrusion that contacts a bottom surface portion 81 of the lower magnetic shield 8 described later.

  The lower magnetic shield 8 is made of, for example, a magnetic material having a high magnetic permeability, and is provided in a generally rectangular shape when viewed from above. The lower magnetic shield 8 includes a flat bottom surface portion 81 and a pair of side walls 82 extending upward and formed by bending. In the bottom surface portion 81, a notch portion 81 a is provided in the vicinity of the center position of the side not connected to the side wall 82. Further, notch portions 81 b are provided in the vicinity of the four corner portions of the bottom surface portion 81. These notches 81 a and 81 b are provided to avoid the protrusion 74 and the hook leg 77 of the inner case 7 when the lower magnetic shield 8 is attached to the lower surface of the inner case 7.

  The lower magnetic shield 8 is disposed in the outer case 10 in a state where both end portions of the side wall 82 are in contact with the side surface portion of the outer rib 104a in the outer case 10 and the outer surface portion of the side wall 82 is in contact with the inner surface portion of the inner rib 104a. Be placed. With this configuration, the positional accuracy of the lower magnetic shield 8 with respect to the outer case 10 in the front-rear and left-right directions can be increased.

  Similar to the lower magnetic shield 8, the upper magnetic shield 9 is made of, for example, a magnetic material having a high magnetic permeability and is generally rectangular in top view. The upper magnetic shield 9 includes a flat top surface portion 91, a side surface portion 92 extending downward and formed by bending, and an inner portion formed by bending a portion of the side surface portion 92. A leg portion 93 extending to the side, a discharge portion 94 (see FIG. 2) provided on an extension line of at least one leg portion 93, and a part of the top surface portion 91 and the side surface portion 92. Cable through-holes 95 formed.

  Of the side surface portions 92, the rear side surface portion 92 is provided to extend downward from the other side surface portions 92. A slit 96 is provided at the center position at the lower end of the pair of side surface portions 92 facing each other in the front-rear direction. A rib 79 of the inner case 7 is inserted into the slit 96. With this configuration, the positional accuracy in the left-right direction of the upper magnetic shield 9 relative to the inner case 7 can be increased.

  The outer case 10 is formed by molding, for example, an insulating resin material, and is provided in a box shape that opens upward. The outer case 10 includes a bottom surface portion 101 having a generally rectangular shape when viewed from above, and a side wall 102 provided orthogonal to the bottom surface portion 101. Here, FIG. 3 is a top view of the outer case 10. 3 is the front side of the current sensor 1, the upper direction shown in FIG. 3 is the rear side of the current sensor 1, the left direction shown in FIG. 3 is the left side of the current sensor 1, 3 is the right side of the current sensor 1.

  A plurality of (two in the present embodiment) through-holes 103a having a generally circular shape are provided in the vicinity of the center position of the opposite sides in the front-rear direction of the bottom surface portion 101. Further, a plurality of (four in the present embodiment) through-holes 103b having a generally rectangular shape are provided in the vicinity of the four corners of the bottom surface portion 101.

  The through-hole 103a is inserted into the protrusion 74 of the inner case 7, thereby positioning the inner case 7 in the front-rear and left-right directions with respect to the outer case 10, and a first for fixing the outer case 10 and the inner case 7 together. It can be used as a case fixing hole. On the other hand, the through hole 103b is inserted into the hook leg 77 of the inner case 7 and snap-coupled with the hook 77a, thereby positioning the inner case 7 in the vertical direction with respect to the outer case 10, and the outer case 10 and the inner case. 7 can be used as a second case fixing hole. With this configuration, the positional accuracy of the inner case 7 relative to the outer case 10 can be increased.

  Outer ribs 104a and inner ribs 104b projecting inward are provided at the lower ends of the side walls 102 facing in the left-right direction. The outer ribs 104a are provided in a pair (two) with respect to the one side wall 102, and are generally formed in a quadrangular prism shape. The inner ribs 104b are provided so as to be sandwiched between the pair of outer ribs 104a, and a plurality (four in this embodiment) are provided on one side wall 102. The inner rib 104b is configured to be smaller than the outer rib 104a, and the upper side thereof is configured to have an oblique shape with the outer side being higher and the inner side being lower.

  The outer rib 104 a contacts the both end portions of the side wall 82 of the lower magnetic shield 8, thereby positioning the lower magnetic shield 8 in the front-rear direction with respect to the outer case 10. The inner rib 104 b contacts the outer side of the side wall 82 of the lower magnetic shield 8, thereby positioning the lower magnetic shield 8 in the left-right direction with respect to the outer case 10. With this configuration, the positional accuracy of the lower magnetic shield 8 with respect to the outer case 10 can be increased.

  A plurality of protrusions 105 protruding outward are provided on the outside of the side wall 102. These protrusions 105 can be used as cover pressing protrusions that snap-engage with openings 114a provided on an extension piece 114 of the cover 11 described later.

  A slit 106 is provided at the center position at the upper end of the side wall 102 facing in the left-right direction. The slit 106 can be used as a first cover fixing slit into which a rib 113a provided on an extending piece 113 of the cover 11 described later is inserted.

  The front side wall 102 has a recess 102a. At the upper end of the rear side wall 102, a groove 107 having a semicircular cross section is provided for positioning the cable 5 in the current sensor 1 and positioning it.

  The cover 11 is formed by molding an insulating resin material, for example, and has a generally rectangular shape when viewed from above. The cover 11 includes a flat top surface portion 111, a wall-shaped portion 112 extending downward and formed by bending, and a plurality of extending pieces 113 and 114 extending downward from the top surface portion 111. And a groove 115 provided on the lower surface of the rear surface side of the top surface portion 111 and a protrusion 116 provided on the lower surface of the top surface portion 111. The protrusion 116 has a generally circular shape.

  The extension piece (second extension piece) 113 is provided with a rib 113a protruding outward. The rib 113 a can be used as a first cover fixing rib for positioning the cover 11 with respect to the outer case 10 by being inserted into the slit 106 of the outer case 10. With this configuration, the positional accuracy of the cover 11 with respect to the outer case 10 in the left-right direction can be increased.

  The extension piece (first extension piece) 114 is provided with an opening 114a. The opening 114 a of the extension piece 114 can be used as a cover pressing hole for attaching the cover 11 to the outer case 10 by snap-coupling with the protrusion 105 of the outer case 10. When the cover 11 is attached to the outer case 10 in this way, the protrusion 116 provided on the lower surface of the top surface portion 111 contacts the top surface portion 91 of the upper magnetic shield 9. With this configuration, it is possible to prevent the upper magnetic shield 9 from floating and to easily assemble the outer case 10 and the cover 11.

  The groove 115 has a semicircular cross section. That is, by arranging the groove portion 107 of the outer case 10 and the groove portion 115 of the cover 11 to face each other, the groove portions 107 and 115 having a semicircular cross section are connected to form a circular introduction hole. . By making the diameter of the introduction hole and the diameter of the cable 5 substantially the same, the cable 5 can be introduced into the outer case 10 and the cover 11 without creating an extra gap. Therefore, it becomes possible to make it difficult to receive the influence of the interference by the magnetic field from the outside of the current sensor 1.

  Then, the state which assembled the current sensor 1 which concerns on this Embodiment is demonstrated. FIG. 4 is a perspective view showing the assembled state of the current sensor 1 from above. FIG. 5 is a cross-sectional view of the current sensor 1 shown in FIG. FIG. 6 is a perspective view when the outer case 10 and the cover 11 are removed from the current sensor 1 shown in FIG. FIG. 7 is a perspective view showing the current sensor 1 shown in FIG. 5 from the rear side. FIG. 8 is a perspective view when the upper magnetic shield 9 is removed from the current sensor 1 shown in FIG.

  As shown in FIGS. 4 and 5, when the current sensor 1 having such a configuration is assembled, components from the lower magnetic shield 8 to the upper magnetic shield 9 are accommodated in the outer case 10 and the cover 11. . The current path 6 is exposed from the front side and the rear side of the current sensor 1, and the cable 5 is exposed from the rear side. A rib 113 a of the cover 11 is inserted into the slit 106 of the outer case 10. With this configuration, the positional accuracy of the cover 11 with respect to the outer case 10 in the left-right direction can be increased.

  To assemble the current sensor 1, first, the lower magnetic shield 8 is placed on the outer case 10 using the outer rib 104 a and the inner rib 104 b as a guide. Thereafter, the inner case 7 through which the current path 6 is inserted is placed so that the protrusion 74 and the hook leg 77 are inserted into the through holes 103a and 103b of the outer case 10, respectively. Thereafter, the insulating substrate 2 on which the magnetoelectric conversion element 3 and the connector 4 are mounted is placed on the inner case 7 so that the protrusion 73 is inserted into the through hole 21 of the insulating substrate 2. Thereafter, the upper magnetic shield 9 is placed on the inner case 7 so that the leg portion 93 contacts the protrusion 78. Thereafter, the cable 5 is introduced from the cable through hole 95 of the upper magnetic shield 9, and the cable 5 is connected to the connector 4 mounted on the insulating substrate 2. Finally, the opening 114 a of the cover 11 and the protrusion 105 of the outer case 10 are snap-coupled to attach the cover 11 to the outer case 10. With such a configuration, the current sensor 1 can be easily assembled, and each component can be arranged with high positional accuracy. However, the assembly order is not limited to this, and can be changed as appropriate.

  A protrusion 74 of the inner case 7 is inserted into the through hole 103a of the outer case 10 and positioned and fixed. With this configuration, the positional accuracy of the outer case 10 and the inner case 7 in the front-rear and left-right directions can be increased. Further, the hook leg 77 of the inner case 7 is inserted into the through hole 103b of the outer case 10 and snap-engaged with the hook 77a. With this configuration, the vertical position accuracy of the outer case 10 and the inner case 7 can be increased.

  An inner case 7 is disposed on the lower magnetic shield 8 disposed in the outer case 10. At this time, the protrusion 75 of the inner case 7 contacts the upper surface of the bottom surface portion 81 of the lower magnetic shield 8. With this configuration, the positional accuracy of the lower magnetic shield 8 in the vertical direction can be increased. A cover 11 is disposed on the upper magnetic shield 9 disposed on the inner case 7. At this time, the protrusion 116 of the cover 11 contacts the upper surface of the top surface portion 91 of the upper magnetic shield 9. With this configuration, the positional accuracy of the upper magnetic shield 9 in the vertical direction can be increased.

  Since both the lower magnetic shield 8 and the upper magnetic shield 9 are arranged with high positional accuracy in the vertical direction, they can be arranged with high precision so as to minimize the distance between the lower magnetic shield 8 and the upper magnetic shield 9. it can. As a result, the entire apparatus can be reduced in size. Further, since the distance between the lower magnetic shield 8 and the upper magnetic shield 9 is short, static electricity accumulated in the lower magnetic shield is discharged via the upper magnetic shield 9.

  The leg portions 93 of the upper magnetic shield 9 and the inner side surfaces of the discharge portion 94 are in contact with the protrusions 78 provided on the upper end portion of the side wall 72 of the inner case 7. With this configuration, the positional accuracy in the front-rear direction of the upper magnetic shield 9 relative to the inner case 7 can be increased.

  The leg portion 93 is positioned so as to contact the upper end portion of the side wall 72 of the inner case 7 and is disposed on the inner case 7. On the other hand, the discharge part 94 is disposed at a position facing the ground electrode 22 on the insulating substrate 2. Since the leg portion 93 is disposed outside the insulating substrate 2, the discharge from the leg portion 93 where the discharging portion 94 is not provided toward the electronic component mounted on the insulating substrate 2 is prevented. With this configuration, the discharge unit 94 serves as a current-carrying needle when static electricity is generated, and causes a current to flow through the ground electrode 22. Therefore, ESD measures can be taken on the current sensor 1 without increasing the thickness of the inner case 7 on which the insulating substrate 2 is placed.

  As shown in FIGS. 6 and 7, the inner case 7 through which the current path 6 is inserted and the insulating substrate 2 is fixed is sandwiched by a pair of magnetic shields (lower magnetic shield 8 and upper magnetic shield 9) from above and below. Covered with. A rib 79 of the inner case 7 is inserted into the slit 96 of the upper magnetic shield 9. Further, with this configuration, it is possible to improve the positional accuracy of the upper magnetic shield 9 with respect to the inner case 7 in the left-right direction.

  Further, the insulating substrate 2 is positioned via the protrusion 73 and fixed to the inner case 7. Thus, since the insulating substrate 2 and the upper magnetic shield 9 are respectively fixed to the inner case 7 that is the same member, the positional accuracy of the upper magnetic shield 9 with respect to the insulating substrate 2 in the vertical direction can be increased. That is, the interval between the insulating substrate 2 and the upper magnetic shield 9 can be set with high accuracy.

  Here, the distance between the discharge portion 94 and the ground electrode 22 is equal to the height difference between the upper end portion of the side wall 72 and the upper surface of the insulating substrate 2. That is, by adjusting the height of the side wall 72 or the height of the protrusion 73, the interval between the discharge portion 94 and the ground electrode 22 can be easily set to a distance at which electrostatic discharge easily occurs. For example, by designing the upper end portion of the side wall 72 to be located above the upper surface of the insulating substrate 2 fixed to the inner case 7 within a range of 0.1 mm or more and 1 mm or less, the discharge portion 94 and the ground can be grounded. The distance from the electrode 22 can be set within a range of 0.1 mm to 1 mm. The shorter the distance between the discharge portion 94 and the ground electrode 22, the easier the discharge from the discharge portion 94 occurs when static electricity is generated.

  The upper magnetic shield 9 is assembled by being placed on the inner case 7 so that the leg portion 93 contacts the upper end portion of the side wall 72 of the inner case 7. Here, since the characteristics of the magnetic shield are irreversibly deteriorated when heated, it is difficult to fix the magnetic shield by a method such as soldering. According to the current sensor 1 according to the present embodiment, the upper magnetic shield 9 can be placed with high positional accuracy by placing it on the inner case 7 without using a method such as soldering. It is possible to achieve both an improvement in ease of assembly and ease of assembly.

  As shown in FIG. 8, the projection 73 of the inner case 7 is inserted into the through hole 21 of the insulating substrate 2 to be positioned and fixed. With this configuration, the height difference between the upper end portion of the side wall 72 of the inner case 7 and the upper surface of the insulating substrate 2 can be set to a desired value. With this configuration, the pair of magnetic shields (the lower magnetic shield 8 and the upper magnetic shield 9) can be arranged at a certain distance from the insulating substrate 2 on which electronic components are mounted. The distance between the pair of magnetic shields and the insulating substrate 2 may be set as appropriate depending on the size of the magnetic shield, the electrostatic voltage applied to the current sensor 1, and the distance between the discharge portion 94 and the ground electrode 22. .

  As described above, according to the current sensor 1 according to the present embodiment, the discharge part 94 of the upper magnetic shield 9 is disposed to face the ground electrode 22 of the insulating substrate 2 and the leg part 93 is insulated. Since it is arranged outside the substrate 2, when static electricity is generated, the discharge part 94 acts as a current-carrying needle and releases the current to the ground electrode 22, and the electronic parts mounted on the insulating substrate 2 from the leg part 93. Since the directed discharge is prevented, ESD countermeasures can be taken without increasing the thickness of the inner case 7 on which the insulating substrate 2 is placed. Therefore, it is possible to provide the current sensor 1 that can downsize the entire apparatus while taking ESD countermeasures.

  Further, according to the current sensor 1, the insulating substrate 2 is fixed by inserting the protrusion 73 of the inner case 7 into the through hole 21 of the insulating substrate 2, and the upper magnetic shield 9 is attached to the upper end of the side wall 72 of the inner case 7. Since the upper magnetic shield 9 is fixed when the legs 93 come into contact with each other, the insulating substrate 2 and the upper magnetic shield 9 are respectively fixed to the inner case 7 that is the same member. The positional accuracy in the vertical direction of the shield 9 can be increased, and the interval between the insulating substrate 2 and the upper magnetic shield 9 can be set with high accuracy. Therefore, the interval between the discharge part 94 and the ground electrode 22 can be shortened, and the discharge part 94 can be discharged efficiently.

  In addition, this invention is not limited to the said embodiment, It can implement variously. In the above-described embodiment, the size, shape, and the like illustrated in the accompanying drawings are not limited thereto, and can be appropriately changed within a range in which the effect of the present invention is exhibited. In addition, various modifications can be made without departing from the scope of the object of the present invention.

  For example, in the above embodiment, the case where the current path 6 is insert-molded and embedded in the insertion portion 76 of the inner case 7 is described. However, the configuration for fixing the current path 6 to the inner case 7 is not limited to this and can be changed as appropriate. For example, it is good also as a structure which provides the accommodating part which accommodates the electric current path 6 in the lower surface of the bottom part 71 of the inner side case 7, and closes the opening of this accommodating part with a plate-shaped member after accommodating the electric current path 6 in this accommodating part. By comprising in this way, the electric current path 6 can be fixed to the inner side case 7 by an assembly.

1 Current sensor 2 Insulating substrate 21 Through hole (fixed hole)
22 Ground electrode 3 Magnetoelectric conversion element 4 Connector 5 Cable 5a Connector 6 Current path 61 Through hole 7 Inner case 71 Bottom 72 Side wall 73 Protrusion (substrate fixing protrusion)
73a Projection lower part 73b Projection upper part 74 Projection (case fixing projection)
75 Protrusion (lower magnetic shield holding protrusion)
76 Insertion part 77 Hook leg 77a Hook 78 Projection (upper magnetic shield fixing projection)
79 Rib (Upper magnetic shield fixing rib)
8 Lower magnetic shield 81 Bottom surface portion 81a, 81b Notch portion 82 Side wall 9 Upper magnetic shield 91 Top surface portion 92 Side surface portion 93 Leg portion 94 Discharge portion 95 Cable through hole 96 Slit 10 Outer case 101 Top surface portion 102 Side wall 102a Recessed portion 103a Through Hole (first case fixing hole)
103b Through hole (second case fixing hole)
104a outer rib 104b inner rib 105 protrusion (cover pressing protrusion)
106 slit (first cover fixing slit)
107 Groove portion 11 Cover 111 Top surface portion 112 Wall-like portion 113 Extension piece (second extension piece)
113a rib (first cover fixing rib)
114 Extension piece (first extension piece)
114a Opening (Cover holding hole)
115 Groove 116 Protrusion (Upper magnetic shield pressing protrusion)

Claims (11)

An insulating substrate;
A magnetoelectric transducer provided on the insulating substrate;
An insulating inner case on which the insulating substrate is placed;
A current path fixed to the inner case;
A metal upper magnetic shield and a lower magnetic shield covering the inner case from above and below,
The inner case includes an insertion portion for inserting the current path, a bottom portion provided with a substrate fixing protrusion for fixing the insulating substrate, and a plurality of side walls.
The upper magnetic shield has a top surface portion, a plurality of side surface portions, and a plurality of leg portions provided by bending a part of the side surface portion,
The insulating substrate has a fixing hole through which the substrate fixing protrusion is inserted;
The substrate fixing protrusion of the inner case is inserted into the fixing hole of the insulating substrate so that the insulating substrate is positioned in the inner case, and the upper magnetic field is formed at the upper ends of the plurality of side walls of the insulating inner case. By installing the plurality of leg portions of the shield, the upper magnetic shield is positioned on the inner case,
Further, the upper magnetic shield is provided with a discharge part on at least one extension line of the plurality of legs, and the insulating substrate has a ground electrode provided at a position facing the discharge part. Characteristic current sensor. In the upper magnetic shield, the leg portions are provided at both end portions of the opposing side surface portions,
The inner case is provided with a pair of upper magnetic shield fixing protrusions protruding upward from the upper end on each of the opposing side walls,
The current sensor according to claim 1, wherein the upper magnetic shield fixing protrusion is in contact with a side surface portion of the leg portion. An outer case on which the inner case and the lower magnetic shield are placed;
The outer case is provided with a pair of outer ribs protruding inward on each of the opposing side walls,
The current sensor according to claim 1, wherein the outer rib is in contact with both end portions of a side surface portion of the lower magnetic shield. The outer case is provided with a plurality of inner ribs protruding inward on the opposing side walls,
The current sensor according to claim 3, wherein the inner rib is in contact with an outer surface of a side surface portion of the lower magnetic shield. The outer case is provided with a plurality of first case fixing holes on the bottom surface,
The inner case is provided with a plurality of case fixing protrusions that protrude downward from the bottom,
The current sensor according to claim 3 or 4, wherein the case fixing protrusion is inserted into the first case fixing hole. The outer case is provided with a plurality of rectangular second case fixing holes on the bottom surface,
The inner case is provided with a hook leg that extends downward from the side wall and has a hook at the tip,
The current sensor according to claim 3, wherein the hook leg is inserted into the second case fixing hole. The inner case is provided with a plurality of lower magnetic shield pressing protrusions that protrude downward from the bottom surface,
The current sensor according to claim 3, wherein the lower magnetic shield pressing protrusion is in contact with a bottom surface portion of the lower magnetic shield. The upper magnetic shield is provided with a cable through hole,
The current sensor according to any one of claims 1 to 7, wherein a cable penetrating the cable through hole is electrically connected to a wiring pattern provided on the insulating substrate via a connector. . The inner case is provided with an upper magnetic shield fixing rib on each opposing side wall,
The upper magnetic shield is provided with a slit in each of the opposing side surface portions,
The current sensor according to any one of claims 4 to 8, wherein the upper magnetic shield fixing rib is disposed in the slit. A cover for covering the upper surface of the outer case;
The cover includes a top surface portion, an upper magnetic shield pressing protrusion protruding downward from the top surface portion, and a first extending piece provided with a cover pressing hole extending downward from an outer edge of the top surface portion. And
The outer case is provided with a cover pressing protrusion that protrudes outward from the side wall,
The upper magnetic shield pressing protrusion is in contact with the top surface portion of the upper magnetic shield,
The current sensor according to any one of claims 3 to 8, wherein the cover pressing hole and the cover pressing protrusion are mechanically joined by snap fitting. The cover is provided with a second extension piece provided with a first cover fixing rib, extending downward from an orthogonal outer edge of the top surface portion,
The outer case is provided with a first cover fixing slit on the side wall,
The current sensor according to claim 10, wherein the first cover fixing rib is disposed in the first cover fixing slit.

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