JP2012163401A - Current sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a current sensor that can position a magnetic detection element with high accuracy.SOLUTION: A current sensor 1 includes an annular core 10 configured by a metal magnetic material and having a gap 22, and a Hall IC 12 provided in the inside of the gap 22. The current sensor 1 includes a resin substrate 16 on which the Hall IC 12 is installed and a metal magnetic plate 18 to which the resin substrate 16 is fixed, and the magnetic plate 18 is engaged with and fixed to the annular core 10 in the gap 22.

Description

  The present invention relates to a current sensor for measuring a current flowing through a conductor.

  There is a current sensor that measures the value of a current flowing through a conductor during charging or discharging in an HV (hybrid car) or EV (electric car) motor or battery. Such a current sensor is used in an environment in which a large magnetic field noise from the outside (for example, a conductor such as a bus bar of another phase in the vicinity) is constantly applied. For this reason, if the magnetic detection element provided in the current sensor has low alignment accuracy and the magnetic detection element is not arranged at a predetermined position, the magnetic detection element senses external magnetic field noise, and the current sensor has a decrease in measurement accuracy. Measurement errors are likely to occur.

  Here, in Patent Document 1, in order to stably and accurately arrange the magnetic detection element at the center position between both end faces of the ring-shaped magnetic core in the gap portion of the ring-shaped magnetic core, the magnetic detection element is placed in a resin holder. A current sensor having a structure in which the holder is inserted into a gap portion of a ring-shaped magnetic core is disclosed.

JP 2010-71822 A

  However, in order to insert the magnetic detection element into the holder as in the current sensor of Patent Document 1, an insertion hole for inserting the magnetic detection element is formed larger than the magnetic detection element, and the insertion hole and the magnetic detection element are It is necessary to provide clearance between them. If a clearance is provided between the insertion hole and the magnetic detection element in this manner, the magnetic detection element cannot be accurately positioned, and the alignment accuracy of the magnetic detection element is reduced. On the other hand, if the magnetic detection element is press-fitted into the holder without providing a clearance between the insertion hole and the magnetic detection element, stress acts on the magnetic detection element and affects the measurement accuracy of the current sensor. Moreover, when the gap part of a ring-shaped magnetic core is wide, since it is necessary to enlarge a holder, useless resin material increases and manufacturing cost will increase.

  Therefore, the present invention has been made to solve the above-described problems, and an object of the present invention is to provide a current sensor that can perform highly accurate alignment of the magnetic detection elements.

  One aspect of the present invention made to solve the above-described problem is a current sensor having an annular core made of a metal magnetic material and having a gap, and a magnetic detection element provided in the gap. And a metal magnetic member to which the resin substrate is fixed, and the magnetic member is fixed by engaging with the annular core at the gap. To do.

  According to this aspect, since both the annular core and the magnetic member are made of metal and the processing accuracy can be increased, the alignment accuracy between the annular core and the magnetic member can be increased. And since the resin board | substrate which mounted the magnetic detection element is being fixed to the magnetic member, the precision of alignment with a cyclic | annular core and a magnetic detection element can also be improved. This improves the measurement accuracy of the current sensor.

  In addition, since the magnetic member is engaged with the annular core, the external magnetic field passes through the magnetic member, so that it is difficult to reach the magnetic detection element. Therefore, the current sensor is resistant to external magnetic field noise, and the influence of the external magnetic field on the current sensor is reduced.

  In said aspect, it is preferable that the said annular core is provided with the recessed part which the said magnetic member engages.

  According to this aspect, it is possible to easily align the annular core and the magnetic member by fitting the magnetic member into the concave portion of the annular core to be engaged. Thus, the magnetic detection element mounted on the resin substrate fixed to the magnetic member can be accurately and easily aligned with the annular core.

  In said aspect, it is preferable that the said recessed part is formed so that it may dent in the internal diameter direction from the position of the outer peripheral surface of the said annular core.

  According to this aspect, since the magnetic member can be fixed to the annular core in the vicinity of the outer peripheral surface of the annular core, the external magnetic field easily passes through the magnetic member, and therefore, it is more difficult to reach the magnetic detection element. Therefore, the influence of the external magnetic field on the current sensor is further reduced, so that the measurement accuracy of the current sensor is improved.

  In said aspect, it is preferable that the said magnetic member is provided with the convex part engaged with the said annular core.

  According to this aspect, the annular core and the magnetic member can be easily aligned by engaging the annular core with the convex portion of the magnetic member inserted into the gap of the annular core. Thus, the magnetic detection element mounted on the resin substrate fixed to the magnetic member can be accurately and easily aligned with the annular core.

  In said aspect, it is preferable that the said convex part is engaged in the state protruded in the internal diameter direction from the position of the outer peripheral surface of the said annular core.

  According to this aspect, since the magnetic member can be fixed to the annular core in the vicinity of the outer peripheral surface of the annular core, the external magnetic field easily passes through the magnetic member, so that it is more difficult to reach the magnetic detection element. Therefore, the influence of the external magnetic field on the current sensor is further reduced, so that the measurement accuracy of the current sensor is improved.

  In the above aspect, the magnetic member has an opening in the center, and the resin substrate is attached to the magnetic member such that a position where the magnetic detection element is mounted on the resin substrate is positioned at the opening. It is preferable that it is fixed.

  According to this aspect, it becomes easy to wire circuit components such as a harness connected to the resin substrate in order to capture the detection signal of the magnetic detection element, and the resin substrate and the magnetic member can be easily fixed.

  According to the current sensor of the present invention, the magnetic detection element can be aligned with high accuracy.

It is a front sectional view of the current sensor according to the embodiment. It is a side view of the current sensor concerning an embodiment. It is a figure which shows a mode that a resin substrate and a magnetic board are joined. It is a front sectional view of a magnetic plate subassembly. It is a front sectional view which shows a mode that a magnetic board subassembly is fixed to a cyclic | annular core. It is a side view which shows a mode that a magnetic board subassembly is fixed to a cyclic | annular core. It is a side view which shows the modification which fixes a magnetic board subassembly to an annular core. It is a front sectional view of a current sensor according to a first modification. It is a front sectional view of a current sensor according to a second modification. It is a front sectional view of the current sensor concerning the 3rd modification. It is a front sectional view of the current sensor concerning the 4th modification.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, embodiments of the invention will be described in detail with reference to the accompanying drawings.

[Configuration of current sensor]
As shown in FIGS. 1 and 2, the current sensor 1 of this embodiment includes an annular core 10, a Hall IC 12, a capacitor 14, a resin substrate 16, a magnetic plate 18, a harness 20, and the like. 1 is a front sectional view of the current sensor 1, and FIG. 2 is a side view of the current sensor 1 (a view when FIG. 1 is viewed from below).

  The annular core 10 is made of a metal magnetic material such as a laminated steel plate, permalloy, or a ferrite magnetic material such as a dust core, and is formed in an annular shape. The annular core 10 is not limited to the rectangular shape as illustrated in FIG. 1, and may be formed in a circular shape. The annular core 10 includes a gap 22 as a gap, and the Hall IC 12 is disposed inside the gap 22. The annular core 10 forms a magnetic path through which a magnetic flux generated by a current flowing through a conductor to be measured passes through a conductor (not shown) inside the inner peripheral surface.

  The Hall IC 12 is a magnetic detection element incorporating a Hall element and a signal conversion circuit. The Hall IC 12 is a magnetic detection element that detects a magnetic field by using the Hall effect, and detects the strength of the magnetic field generated in the gap 22 by an electric current flowing through a conductor to be measured (not shown) as an output voltage. To do. Since the strength of the magnetic field is proportional to the magnitude of the current flowing through the conductor to be measured, the value of the current flowing through the conductor to be measured can be obtained from the output voltage of the Hall IC 12. In the present embodiment, the Hall IC 12 is mounted on the resin substrate 16 by soldering or the like. It is also conceivable to mount a plurality of Hall ICs 12.

  The resin substrate 16 is a flat substrate, is mounted with a Hall IC 12 and a capacitor 14, and the harness 20 is connected thereto. The resin substrate 16 is bonded to the magnetic plate 18. The bonding method of the resin substrate 16 and the magnetic plate 18 may be any of bonding using an adhesive tape, bonding using an adhesive, bonding using screws, bonding by caulking, bonding by press-fitting, bonding by welding, and bonding by welding.

  The magnetic plate 18 is made of a flat metal magnetic body. The magnetic plate 18 includes an opening 24 and is connected in the direction of magnetic flux flow (the left-right direction in FIG. 2) at portions 26 and 28 on both sides of the opening 24. The magnetic plate 18 is engaged and fixed to the annular core 10 so as to be fitted into a recess 30 provided in the gap 22 portion of the annular core 10. The recess 30 is formed so as to be recessed in the inner diameter direction from the position of the outer peripheral surface 52 of the annular core 10 (see FIG. 5). Further, the resin substrate 16 and the magnetic plate 18 are fixed so that the location where the Hall IC 12 is mounted on the resin substrate 16 is positioned at the position of the opening 24.

  Here, since both the annular core 10 and the magnetic plate 18 are made of metal, the processing accuracy can be increased, so that the alignment accuracy between the annular core 10 and the magnetic plate 18 can be increased. Since the Hall IC 12 is integrated with the magnetic plate 18 via the resin substrate 16, the alignment accuracy between the annular core 10 and the Hall IC 12 is increased by increasing the alignment accuracy between the annular core 10 and the magnetic plate 18. The accuracy can be improved.

  Also, if the annular core has a high permeability, the annular core also focuses the external magnetic field, and the current sensor may cause an error in the current measurement value due to a decrease in measurement accuracy due to the influence of the focused external magnetic field. is there. However, in the present embodiment, as shown in FIGS. 1 and 2, the magnetic plate 18 is fitted in the gap 22. The magnetic plate 18 is connected in the magnetic flux flow direction (left-right direction in FIG. 2) at the portions 26 and 28 on both sides of the opening 24. Therefore, the external magnetic field passes through the magnetic plate 18 and does not reach the Hall IC 12. As a result, the current sensor 1 is not easily affected by the external magnetic field, the measurement accuracy is not lowered, and no error occurs in the current measurement value.

[Manufacturing method of current sensor]
Next, a method for manufacturing the current sensor 1 having such a configuration will be described. First, as shown in FIGS. 3 and 4, for the resin substrate 16 on which the Hall IC 12 and the capacitor 14 are mounted and the magnetic plate 18, the distance from the side surface 32 of the magnetic plate 18 to the Hall IC 12 is a predetermined distance L (see FIG. 3). 4), the surface 34 of the resin substrate 16 and the surface 36 of the magnetic plate 18 are bonded together while positioning with a jig (not shown) or the like. In this way, the magnetic plate 18 and the Hall IC 12 are aligned to join the resin substrate 16 and the magnetic plate 18 to form the magnetic plate subassembly 38 shown in FIG.

  Next, as shown in FIG. 5, the annular core 10 and the magnetic plate subassembly 38 are joined. At this time, the annular core 10 is processed in advance so that the distance between the surface 40 of the recess 30 and the center line of the gap 22 becomes a predetermined distance L. Then, the magnetic plate subassembly 38 is fitted and joined to the recess 30 of the annular core 10. Thereby, as shown in FIG. 1, the current sensor 1 in which the Hall IC 12 is arranged on the center line of the gap 22 can be manufactured.

  At this time, as shown in FIG. 6, the surface 42 of the annular core 10 and the surface 44 of the magnetic plate subassembly 38 are positioned to position the magnetic plate subassembly 38 in the central axis direction of the annular core 10 (vertical direction in FIG. 6). Alignment is performed with a jig (not shown) so as to match. Thereby, the current sensor 1 as shown in FIG. 2 can be manufactured.

  As shown in FIG. 7, a protrusion 46 that protrudes toward the inside of the gap 22 is formed in the gap 22 portion of the annular core 10, and the fitting portion 48 is formed on the magnetic plate 18 of the magnetic plate subassembly 38. An example of forming the above is also conceivable. Then, it is conceivable to align the surface 42 of the annular core 10 and the surface 44 of the magnetic plate subassembly 38 by fitting the protrusion 46 and the fitting portion 48 together. In addition, in the example shown in FIG. 7, although the protrusion part 46 and the fitting part 48 are formed in two places, it is not limited to this, You may form three places or four places.

[Modification]
In addition, the following embodiments can be considered as modified examples. First, as shown in FIG. 8, the current sensor 1A according to the first modification is provided with a convex portion 50 on the magnetic plate 18. Then, the resin substrate 16 and the magnetic plate 18 are joined so that the convex portion 50 is positioned on the side opposite to the resin substrate 16 to form the magnetic plate subassembly 38. Then, the magnetic plate 18 is engaged with and fixed to the annular core 10 so that the convex portion 50 is fitted into the gap 22 in a state where the convex portion 50 protrudes in the inner diameter direction from the position of the outer peripheral surface 52 of the annular core 10. In this way, the magnetic plate subassembly 38 is fixed to the annular core 10.

  As described above, according to the first modification, it is not necessary to form the concave portion 30 in the annular core 10, so that the manufacturing cost can be reduced. Further, since the magnetic plate 18 is provided to the outer diameter side of the outer peripheral surface 52 of the annular core 10, the external magnetic field easily passes through the magnetic plate 18 and does not reach the Hall IC 12. Therefore, the current sensor 1A is not easily affected by the external magnetic field, the measurement accuracy is not lowered, and no error occurs in the current measurement value.

  Next, as shown in FIG. 9, the current sensor 1 </ b> B according to the second modification increases the thickness of the magnetic plate 18 so that the magnetic plate 18 protrudes to the outer diameter side from the outer peripheral surface 52 of the annular core 10. Yes. According to the second modified example, the external magnetic field easily passes through the magnetic plate 18 and therefore does not reach the Hall IC 12. Therefore, the current sensor 1B is not easily affected by the external magnetic field, the measurement accuracy is not lowered, and no error occurs in the current measurement value.

  Next, as shown in FIG. 10, in the current sensor 1 </ b> C of the third modification, the magnetic plate 18 has a concave shape, and the resin substrate 16 is fitted in the magnetic plate 18. As described above, according to the third modification, the bonding state between the resin substrate 16 and the magnetic plate 18 becomes stronger, and the alignment accuracy between the magnetic plate 18 and the annular core 10 and the Hall IC 12 can be maintained high. it can.

  Next, as shown in FIG. 11, the current sensor 1 </ b> D of the fourth modified example has a resin substrate 16 and a magnetic plate 18 that are opposite to the arrangement shown in FIG. The plate 18 is disposed, and the resin substrate 16 is disposed on the outer diameter side of the annular core 10.

  In addition, the harness 20 may be mounted on the resin substrate 16 from the inside of the annular core 10. The position where the magnetic plate 18 is fitted may be on the inner diameter side of the annular core 10.

[Effect of this embodiment]
According to the embodiment described above, both the annular core 10 and the magnetic plate 18 are made of metal, and the processing accuracy can be increased. Therefore, the alignment accuracy between the annular core 10 and the magnetic plate 18 can be increased. . And since the resin board | substrate 16 which mounted Hall IC12 by soldering etc. is being fixed to the magnetic board 18, the precision of alignment with the annular core 10 and Hall IC12 can also be improved. Thereby, the measurement accuracy of the current sensor 1 is improved.

  Further, since the magnetic plate 18 is engaged with the annular core 10, the external magnetic field passes through the magnetic plate 18, so that it is difficult to reach the Hall IC 12. Therefore, the current sensor 1 is resistant to external magnetic field noise, and the influence of the external magnetic field on the current sensor 1 is reduced.

  Further, the magnetic plate 18 is fitted into the concave portion 30 of the annular core 10 to be engaged with each other, whereby the alignment between the annular core 10 and the magnetic plate 18 can be easily performed. Accordingly, the Hall IC 12 mounted on the resin substrate 16 fixed to the magnetic plate 18 can be accurately and easily aligned with the annular core 10.

  Further, since the recess 30 is formed so as to be recessed in the inner diameter direction from the position of the outer peripheral surface 52 of the annular core 10, the magnetic plate 18 can be fixed to the annular core 10 in the vicinity of the outer peripheral surface 52 of the annular core 10. it can. For this reason, the external magnetic field easily passes through the magnetic plate 18, so that it is difficult to reach the Hall IC 12. Therefore, since the influence of the external magnetic field on the current sensor 1 is further reduced, the measurement accuracy of the current sensor 1 is improved.

  Further, the annular core 10 and the magnetic plate 18 can be easily aligned by engaging the annular core 10 with the convex portion 50 of the magnetic plate 18 inserted into the gap 22 of the annular core 10. Can do. Accordingly, the Hall IC 12 mounted on the resin substrate 16 fixed to the magnetic plate 18 can be accurately and easily aligned with the annular core 10.

  Further, since the convex portion 50 of the magnetic plate 18 is engaged in a state protruding from the position of the outer peripheral surface 52 of the annular core 10 in the inner diameter direction, the magnetic plate 18 is annularly formed in the vicinity of the outer peripheral surface 52 of the annular core 10. It can be fixed to the core 10. For this reason, the external magnetic field easily passes through the magnetic plate 18, so that it is difficult to reach the Hall IC 12. Therefore, since the influence of the external magnetic field on the current sensor 1 is further reduced, the measurement accuracy of the current sensor 1 is improved.

  In addition, the magnetic plate 18 has an opening 24 at the center, and the resin substrate 16 is fixed to the magnetic plate 18 so that a position where the Hall IC 12 is mounted on the resin substrate 16 is located in the opening 24. Therefore, it becomes easy to wire circuit components such as the harness 20 connected to the resin substrate 16 in order to capture the detection signal of the Hall IC 12, and the resin substrate 16 and the magnetic plate 18 can be easily fixed.

  It should be noted that the above-described embodiment is merely an example and does not limit the present invention in any way, and various improvements and modifications can be made without departing from the scope of the invention. For example, it is conceivable to directly fix the resin substrate 16 on which the Hall IC 12 is mounted to the annular core 10. Thereby, it can position and fix with respect to the cyclic | annular core 10 directly without going through a casing, a holder, etc., and the highly accurate position alignment of Hall IC12 can be performed.

1 Current sensor 10 Annular core 12 Hall IC
16 Resin substrate 18 Magnetic plate 22 Gap 24 Opening 30 Recess 38 Magnetic plate sub-assembly

Claims (6)

In a current sensor having an annular core made of a metal magnetic body and having a gap, and a magnetic detection element provided inside the gap,
A resin substrate on which the magnetic detection element is mounted;
A metal magnetic member to which the resin substrate is fixed,
The magnetic member is engaged and fixed to the annular core at the gap;
A current sensor. The current sensor of claim 1,
The annular core has a recess with which the magnetic member is engaged;
A current sensor. The current sensor of claim 2,
The recess is formed to be recessed in the inner diameter direction from the position of the outer peripheral surface of the annular core;
A current sensor. The current sensor of claim 1,
The magnetic member includes a convex portion that engages with the annular core;
A current sensor. The current sensor of claim 4,
The convex portion is engaged in a state protruding in the inner diameter direction from the position of the outer peripheral surface of the annular core,
A current sensor. The current sensor according to any one of claims 1 to 5,
The magnetic member has an opening in the center, and the resin substrate is fixed to the magnetic member so that a position where the magnetic detection element is mounted on the resin substrate is located at the position of the opening.
A current sensor.

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