JP2013127424A - Current sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a current sensor having plural ranges with one core, which can detect a current value with higher accuracy.SOLUTION: In an annular core 2 having a gap, the gap is defined by a V-shaped convex surface 21 and a concave surface 22 facing the convex surface in parallel. The gap includes a first gap 31 defined by a convex inner surface 211 of the convex surface 21 and a concave inner surface 221 of the concave surface 22, and a second gap 32 defined by a convex outer surface 212 of the convex surface 21 and a concave outer surface 222 of the concave surface 22 so as to have a gap length different from the first gap 31. A first magnetic sensing element 41 having a magnetic sensing surface 41a in parallel with the convex inner surface 211 and the concave inner surface 221 is disposed in the first gap 31. A second magnetic sensing element 42 having a magnetic sensing surface 42a in parallel with the convex outer surface 212 and the concave outer surface 222 is disposed in the second gap 32.

Description

  The present invention relates to a current sensor using a magnetosensitive element.

  For example, a battery mounted on an automobile has a small discharge current when traveling on a flat road, and a large discharge current when starting the vehicle or traveling on a slope. In other words, a battery mounted on an automobile changes in a wide range of discharge current values. When detecting a wide range of current, it is common to use a current sensor having a plurality of ranges in order to improve detection accuracy. Therefore, a current sensor having a plurality of ranges has been proposed in order to obtain the remaining amount of the battery from the integrated value of the discharge current (Patent Document 1).

  This current sensor includes an annular core having a gap and a magnetosensitive element arranged in the gap. Here, the core is formed so as to make the gap between the opposing ends of the separating ends parallel to each other in a stepped manner in the width direction of the core. Each stepped surface is formed such that the surfaces are parallel to each other. As a result, a plurality of gaps having different gap lengths (opposite intervals between the cut ends) are defined. In each of the plurality of gaps, a magnetosensitive element is arranged such that the magnetosensitive surface is separated and parallel to the end surface. In this way, the current sensor detects the current value according to the magnetic flux density sensed by the magnetosensitive element.

  When a current flows through the current path in which the current sensor as described above is arranged, a magnetic field is generated around the current path, and a magnetic flux is generated along the radial direction of the core (and thus the core gap). When the gap length is small, a sufficient magnetic flux density can be obtained even when the current to be measured is small. However, the range in which the linearity of the output of the magnetic sensor with respect to the magnetic flux density is maintained is limited to the range where the current is small. On the other hand, in the gap having a large gap length, the linearity of the output of the magnetic sensor is guaranteed over a wide range of the current to be measured. However, if the current to be measured is reduced to some extent, the magnetic flux density is reduced as a whole, and the linearity of the output of the magnetic sensor cannot be guaranteed. As a result, when detecting a current value in a wide range, the current sensor detects a small current value for a magnetosensitive element arranged in a gap with a short gap length as a range for detecting a small current value. As a range for detecting a large current value, a magnetosensitive element arranged in a gap having a long gap length is used for detecting a large current value.

JP 7-218552 A

  However, in the current sensor described in Patent Document 1, since gaps having different gap lengths are close to each other, magnetic flux leaks to the close gap. Further, the stepped surfaces of the cut-off end of the core are configured to be parallel to each other and the magnetosensitive surfaces of the magnetosensitive elements are configured to be parallel to each other. On the other hand, the magnetosensitive element easily detects a magnetic flux incident in a normal direction with respect to the magnetosensitive surface. For this reason, the magnetic sensitive element is easily affected by magnetic flux leaking from the adjacent gap, and there is a problem that an error is likely to occur in the detected current value.

  In view of the above, an object of the present invention is to provide a current sensor having a plurality of ranges in one core and capable of detecting a current value with higher accuracy.

  The present invention is a current sensor comprising an annular core having a gap and a magnetosensitive element arranged in the gap, the core having two wall surfaces facing each other through the gap, The wall surface is formed as a V-shaped convex surface whose apex protrudes in the circumferential direction of the core when viewed in the direction in which the current flows, and the other wall surface facing the convex surface corresponds to the convex surface. The gap is composed of a first gap and a second gap, and the first gap is formed by the legs on the radially inner side of the core among the V-shaped legs of the convex surface. A convex inner surface is defined by a concave inner surface formed by a radially inner leg of the core among the concave V-shaped legs, and the second gap is a diameter of the core of the convex V-shaped legs. Convex outer surface with legs on the outside Of the V-shaped legs of the concave surface, the concave outer surface is defined by a radially outer leg of the core, the convex inner surface and the concave inner surface are parallel to each other, and the convex outer surface and the concave outer surface are parallel to each other. Thus, the distance between the convex inner surface and the concave inner surface is different from the distance between the convex outer surface and the concave outer surface, and the first magnetic sensitive element and the second magnetic sensitive element are used as the magnetic sensitive elements. The first magnetosensitive element is disposed in the first gap so that the magnetosensitive surface thereof is parallel to the convex inner surface and the concave inner surface, and the second magnetosensitive element includes The magnetosensitive surface is disposed in the second gap so as to be parallel to the convex outer surface and the concave outer surface.

  According to the present invention, the magnetic flux generated between the convex inner surface and the concave inner surface defining the first gap is incident on the magnetic sensitive surface of the first magnetic sensitive element in the normal direction to define the second gap. Magnetic flux generated between the convex outer surface and the concave outer surface is incident in the normal direction to the magnetic sensitive surface of the second magnetic sensitive element. At this time, the distance between the convex inner surface and the concave inner surface (that is, the gap length of the first gap) is different from the distance between the convex outer surface and the concave outer surface (that is, the gap length of the first gap). . As a result, the magnetic flux density generated in the first gap is different from the magnetic flux density generated in the second gap.

  Furthermore, the convex inner surface, the concave inner surface, and the magnetic sensitive surface of the first magnetic sensitive element are parallel to each other, and the convex outer surface, the concave outer surface, and the magnetic sensitive surface of the second magnetic sensitive element are parallel to each other. Further, the convex inner surface and the convex outer surface intersect at the V-shaped apex. That is, the “surface including the concave inner surface defining the first gap” and the “surface including the magnetic sensitive surface of the first magnetic sensing element” which are parallel to the convex inner surface defining the first gap, and the second gap The “surface including the concave outer surface defining the second gap” and the “surface including the magnetic sensitive surface of the second magnetic sensing element” which are parallel to the defining convex outer surface intersect each other.

  Thereby, even when the magnetic flux leaks from the first gap, the leaked magnetic flux does not enter the normal direction with respect to the magnetic sensitive surface of the second magnetic sensing element, and the magnetic flux leaks from the second gap. Even in this case, the leaked magnetic flux does not enter the normal direction with respect to the magnetosensitive surface of the first magnetosensitive element.

  Therefore, since the magnetic flux incident in the normal direction to the magnetic sensitive surface of the first magnetic sensitive element is a magnetic flux generated in the first gap, the first magnetic sensitive element has a case where the magnetic flux leaks from the second gap. Even so, the magnetic flux generated in the first gap can be sensed better. Similarly, since the magnetic flux incident in the normal direction with respect to the magnetic sensing surface of the second magnetosensitive element is a magnetic flux generated in the second gap, the magnetic flux leaks from the first gap in the second magnetosensitive element. Even in this case, the magnetic flux generated in the second gap can be sensed better. Therefore, since the current sensor of the present invention has a plurality of ranges, even a current sensor having a plurality of gap lengths in one core can detect a current value with higher accuracy.

  In this invention, it is preferable that the angle of the V-shaped vertex of the said convex surface and the said concave surface is 90 degree | times. Thereby, the magnetic sensitive surface of the first magnetic sensitive element and the magnetic sensitive surface of the second magnetic sensitive element are orthogonal to each other. Thereby, the first magnetosensitive element and the second magnetosensitive element can significantly reduce (or minimize) the influence of the magnetic flux leaking from each other in the first gap and the second gap. Here, in the present invention, the angle of the V-shaped apex of 90 degrees does not need to be exactly 90 degrees, and is an angle that can significantly reduce the influence of magnetic flux leaking from the adjacent gap. There may be some errors.

The perspective view which shows the structure of the current sensor of embodiment of this invention. The top view which shows the structure of the current sensor of embodiment. The enlarged view of the core and gap of the current sensor of an embodiment.

  The configuration of the current sensor according to the embodiment of the present invention will be described. As shown in FIG. 1, the current sensor 1 of the present embodiment includes an annular core 2 made of a magnetic material. The core 2 of the present embodiment is an annular one, but may be any annular one, for example, a square annular one. The current sensor 1 arranges the core 2 so as to surround the current path P through which electricity such as a conducting wire flows. At this time, the core 2 is arranged such that the radial direction surface of the core 2 is the normal direction of the current flowing through the current path P.

  In the core 2, gaps (31, 32) that are gaps (spaces) that are spaced apart in the circumferential direction are formed in a part of a section of the entire length in the circumferential direction. Specifically, the core 2 faces the circumferential direction of the core 2 when one wall surface 21 of the two wall surfaces opposed via the gaps (31, 32) is viewed in the direction in which the current flows. Thus, it is formed as a V-shaped convex surface from which the apex 21a protrudes. Hereinafter, the one wall surface 21 is referred to as a “convex surface”, and the wall surface formed by the legs on the radially inner side of the core 2 among the V-shaped legs of the convex surface 21 is referred to as a convex inner surface 211. Of these, the wall surface formed by the radially outer legs of the core 2 is referred to as a convex outer surface 212. At this time, the core 2 is formed so that the angle of the vertex 21a of the convex surface 21 is about 90 degrees. That is, the surface including the convex inner surface 211 and the surface including the convex outer surface 212 intersect at a substantially right angle.

  In the core 2, the other wall surface 22 facing the convex surface 21 is formed as a V-shaped concave surface corresponding to the convex surface 21. That is, the other wall surface 22 is formed as a concave surface that becomes a V-shaped notch with the apex 22a retracted in the circumferential direction of the core 2 when viewed in the direction in which the current flows. Hereinafter, the other wall surface 22 is referred to as a “concave surface”, and the wall surface of the V-shaped legs of the concave surface 22 by the legs on the radially inner side of the core 2 is referred to as a concave inner surface 221, and the V-shaped legs of the concave surface 22 Of these, the wall surface formed by the radially outer legs of the core 2 is referred to as a concave outer surface 222.

  The convex surface 21 and the concave surface 22 are formed such that the convex inner surface 211 and the concave inner surface 221 are substantially parallel, and the convex outer surface 212 and the concave outer surface 222 are substantially parallel. For this reason, the angle of the vertex 22a of the concave surface 22 is about 90 degrees, and the surface including the concave inner surface 221 and the surface including the concave outer surface 222 intersect at a substantially right angle.

  The gap (31, 32) includes a first gap 31 and a second gap 32. The first gap 31 is defined by the convex inner surface 211 and the concave inner surface 221. The second gap 32 is defined by the convex outer surface 212 and the concave outer surface 222. Further, as shown in FIG. 2, the core 2 has a gap length of the first gap 31 (that is, a distance between the convex inner surface 211 and the concave inner surface 221; hereinafter referred to as “first gap length”) L1, The gap length of the second gap 32 (that is, the distance between the convex outer surface 212 and the concave outer surface 222; hereinafter referred to as “second gap length”) L2 is different. In the present embodiment, the first gap length L1 is formed longer than the second gap length L2. As a result, the magnetic flux density generated in the first gap 31 when a current flows through the current path P is smaller than the magnetic flux density generated in the second gap 32.

  A first magnetosensitive element 41 that detects (senses) the strength of the magnetic field in the gap 31 by a magnetic flux incident on the magnetosensitive surface 41 a is disposed in the first gap 31, and in the second gap 32. The second magnetosensitive element 42 that detects (senses) the strength of the magnetic field in the gap 32 by the magnetic flux incident on the magnetosensitive surface 42a is disposed. At this time, the first magnetosensitive element 41 is disposed such that the magnetosensitive surface 41 a is substantially parallel to the convex inner surface 211 and the concave inner surface 221. Similarly, the second magnetosensitive element 42 is disposed such that the magnetosensitive surface 42 a is substantially parallel to the convex outer surface 212 and the concave outer surface 222.

  In the present embodiment, the first magnetosensitive element 41 and the second magnetosensitive element 42 are Hall elements (lead-type Hall elements). The first magnetosensitive element 41 and the second magnetosensitive element 42 output a magnetic flux incident on the magnetosensitive surfaces 41 a and 42 a, that is, a voltage corresponding to the magnetic flux density in the gaps 31 and 32. The current sensor 1 determines the current value of the current path P according to the voltages (that is, the magnetic field strength of each gap (31, 32)) output from the first and second magnetosensitive elements 41 and 42. Detect.

  Further, as described above, since “first gap length L1> second gap length L2”, the current sensor 1 uses the first magnetosensitive element 41 as a large range for detecting a large current, and a small current is generated. The second magnetosensitive element 42 is used as a small range for detection.

  Since the current sensor 1 is configured as described above, when a current flows through the current path P, a magnetic flux along the circumferential direction of the core 2 is generated. The magnetic flux passing through the first gap 31 and the second gap 32 of the core 2 at this time will be described with reference to FIG.

  The magnetic flux passing through the gaps (31, 32) provided in the core 2 that is a magnetic body passes through the shortest distance between the wall surfaces that define the gap of the core 2. That is, the magnetic flux passing through the first gap 31 passes through the shortest distance between the convex inner surface 211 and the concave inner surface 221. At this time, since the convex inner surface 211 and the concave inner surface 221 are formed substantially parallel, the direction of the magnetic flux lines in the first gap 31 is substantially normal to the two surfaces 211 and 221. . As a result, the magnetic flux in the first gap 31 is incident on the magnetosensitive surface 41 a of the first magnetosensitive element 41 substantially in the normal direction. Therefore, the first magnetosensitive element 41 can sense the strength of the magnetic field in the first gap 31 with high accuracy.

  Similarly, the magnetic flux passing through the second gap 32 passes through the shortest distance between the convex outer surface 212 and the concave outer surface 222. At this time, since the convex outer surface 212 and the concave outer surface 222 are formed substantially parallel to each other, the direction of the magnetic flux lines in the second gap 32 is substantially normal to the two surfaces 211 and 221. . As a result, the magnetic flux in the second gap 32 is incident on the magnetosensitive surface 42a of the second magnetosensitive element 42 substantially in the normal direction. Therefore, the second magnetosensitive element 42 can sense the strength of the magnetic field in the second gap 32 with high accuracy.

  On the other hand, since the first gap 31 and the second gap 32 are close to each other, magnetic fluxes passing through the gaps leak from each other (broken line in FIG. 3).

  The leaked magnetic flux does not enter the normal direction with respect to the magnetic sensitive surface of the magnetic sensitive element arranged in the adjacent gap. That is, the magnetic flux leaking from the second gap 32 to the first gap 31 does not enter the normal direction with respect to the magnetic sensitive surface 41 a of the first magnetic sensitive element 41. As a result, the first magnetosensitive element 41 is less sensitive to the magnetic flux leaking from the second gap 32 and can sense the strength of the magnetic field in the first gap 31 with high accuracy. Similarly, the magnetic flux leaking from the first gap 31 to the second gap 32 does not enter the normal direction with respect to the magnetic sensitive surface 42 a of the second magnetic sensitive element 42. As a result, the second magnetosensitive element 42 is less sensitive to magnetic flux leaking from the first gap 31, and can sense the strength of the magnetic field in the second gap 32 with high accuracy.

  Here, the magnetic flux passing through the first gap 31 does not include the magnetic flux leaked from the second gap 32 to the first gap 31, and is between the convex inner surface 211 and the concave inner surface 221 that are wall surfaces that define the first gap 31. It is the magnetic flux that passes through. Similarly, the magnetic flux passing through the second gap 32 does not include the magnetic flux leaked from the first gap 31 to the second gap 32, and is between the convex outer surface 212 and the concave outer surface 222, which are wall surfaces that define the second gap 32. It is the magnetic flux that passes through.

  As described above, when the current flowing through the current path P is small, the current sensor 1 of the present embodiment can detect the current with high accuracy by the second magnetosensitive element 42 and the current flowing through the current path P is large. In this case, the current can be detected with high accuracy by the first magnetosensitive element 41.

  Further, the vertex 21a of the convex surface 21 and the vertex 22a of the concave surface 22 are formed so that the respective angles are about 90 degrees. Thereby, even when the magnetic flux leaks from the first gap 31 to the second gap 32, the angle of the magnetic flux incident on the magnetic sensitive surface 42a of the second magnetic sensitive element 42 becomes substantially parallel, and the leaked magnetic flux The influence on the second magnetosensitive element 42 can be minimized. Similarly, even when the magnetic flux leaks from the second gap 32 to the first gap 31, the angle of the magnetic flux incident on the magnetic sensitive surface 41a of the first magnetic sensitive element 41 becomes almost parallel, and the leaked magnetic flux The influence on the first magnetosensitive element 41 can be minimized.

  In addition, in the current sensor 1 of the present embodiment, each angle of the vertex 21a of the convex surface 21 and the vertex 22a of the concave surface 22 is formed to be about 90 degrees. The angle (acute angle) is larger than 0 degree and smaller than 180 degrees, and the angle of the vertex 21a of the concave surface 22 corresponds to this (the convex inner surface 211 and the concave inner surface 221 are substantially parallel, and the convex outer surface 212 and the concave outer surface 222 (So that they are substantially parallel). As a result, the magnetic flux leaking to the adjacent gap is incident in the normal direction with respect to the magnetosensitive surface of the magnetosensitive element, as compared with the case where the stepped surfaces are formed to be parallel to each other. Can be prevented.

  In the present embodiment, “first gap length L1> second gap length L2” is set, but “first gap length L1 <second gap length L2” may be set. In this case, the current path P is set to When the flowing current is small, the first magnetosensitive element 41 can detect the current with high accuracy, and when the current flowing through the current path P is large, the second magnetosensitive element 42 can detect the current with high accuracy.

  Further, in the current sensor 1 of the present embodiment, the magnetosensitive element is configured by a Hall element, but may be a magnetic sensor other than the Hall element, for example, a Hall IC or a magnetoresistive element.

  DESCRIPTION OF SYMBOLS 1 ... Current sensor, 2 ... Core, 21 ... Convex surface (one wall surface, convex surface), 21a ... Vertex, 211 ... Convex inner surface, 212 ... Convex outer surface, 22 ... Concave surface (the other wall surface, concave surface), 22a ... Vertex, 221 ... concave inner surface, 222 ... concave outer surface, 31 ... first gap (gap, first gap), 32 ... second gap (gap, second gap), 41 ... first magnetic sensitive element (magnetic sensitive element, first sensitive) Magnetic element), 41a ... magnetic sensitive surface, 42 ... second magnetic sensitive element (magnetic sensitive element, second magnetic sensitive element), 42a ... magnetic sensitive surface.

Claims (2)

A current sensor comprising an annular core having a gap, and a magnetosensitive element disposed in the gap,
The core has two wall surfaces facing each other through the gap,
One wall surface is formed as a V-shaped convex surface whose apex projects in the circumferential direction of the core when viewed in the direction in which the current flows,
The other wall surface facing the convex surface is formed as a V-shaped concave surface corresponding to the convex surface,
The gap includes a first gap and a second gap,
The first gap includes a convex inner surface due to a radially inner leg of the core of the convex V-shaped legs and a concave inner surface due to a radially inner leg of the concave V-shaped legs. And is defined by
The second gap includes a convex outer surface due to a radially outer leg of the core of the convex V-shaped legs, and a concave outer surface due to a radially outer leg of the core of the concave V-shaped legs. And is defined by
The convex inner surface and the concave inner surface are parallel to each other, the convex outer surface and the concave outer surface are parallel to each other, and a distance between the convex inner surface and the concave inner surface, and between the convex outer surface and the concave outer surface. Is different from the distance
As the magnetosensitive element, a first magnetosensitive element and a second magnetosensitive element are provided,
The first magnetosensitive element is disposed in the first gap such that a magnetosensitive surface thereof is parallel to the convex inner surface and the concave inner surface,
The current sensor, wherein the second magnetosensitive element is disposed in the second gap so that a magnetosensitive surface thereof is parallel to the convex outer surface and the concave outer surface.   2. The current sensor according to claim 1, wherein an angle between the convex surface and the V-shaped apex of the concave surface is 90 degrees.

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