JP2011112559A - Current sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a current sensor miniaturizing a magnetic body core without narrowing a region where magnetic flux density within a gap of the magnetic body core is uniform. <P>SOLUTION: In the current sensor 10 detecting the level of current flowing through a bus bar 18 inserted into the magnetic body core 12 by a magnetoelectric transducer 16 disposed within the gap 14 of the magnetic body core 12, the magnetic body core 12 includes a first part 12a adjacent to the gap 14 and a second part 12b other than the first part 12a. The sectional area of the first part 12a is formed to be larger than that of the second part 12b. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a current sensor.

  An electric connection box mounted on a vehicle may be provided with a current sensor for detecting the magnitude of a current flowing in a bus bar serving as a current path. As this current sensor, a magnetic proportional current sensor is often used.

  A magnetic proportional current sensor is a magnet-electric transducer such as a Hall element placed in the gap of a magnetic core through which a conductor serving as a current path is inserted, and the magneto-electric transducer controls the strength of the magnetic field in the gap. The magnitude of the current flowing through the conductor is detected by converting it into a voltage signal.

  The magnetic proportional current sensor is used, for example, to detect a current flowing between a battery of a hybrid car or an electric car and an inverter. Moreover, it is used also as a means for detecting the charging / discharging electric current of the lead battery mounted in the vehicle (refer patent document 1).

  By the way, in order to reduce the size of the electrical junction box, it is preferable that the current sensor mounted inside the electrical junction box is miniaturized. In order to reduce the size of the current sensor, it is effective to make the magnetic core occupying most of the projected area of the current sensor as small as possible.

  However, if the magnetic core is made smaller, the magnetic core is more likely to be magnetically saturated, so the range of current values that can be detected by the current sensor becomes smaller. As a result, for example, the battery and the inverter of the hybrid car There is a problem that it becomes difficult to detect a large current flowing therebetween.

  In addition, when the magnetic core is made smaller, the cross-sectional area of the magnetic core becomes smaller, so that the region where the magnetic flux density is uniform in the gap of the magnetic core becomes narrower. For this reason, there exists a problem that the operation | work of alignment of the magnetoelectric conversion element arrange | positioned in a gap will become difficult.

  Therefore, a structure for eliminating the magnetic saturation of the magnetic core has been proposed (see Patent Document 2). However, these magnetic cores have a complicated structure and increase the manufacturing cost. There is a problem of end.

JP 2006-292692 A JP 2008-233303 A

  The present invention has been completed based on the above situation, and a current sensor capable of miniaturizing a magnetic core without narrowing a region where the magnetic flux density is uniform in the gap of the magnetic core. The purpose is to provide.

  The current sensor of the present invention is a current sensor for detecting the magnitude of a current flowing through a conductor inserted through a magnetic core by a magnetoelectric conversion element disposed in a gap of the magnetic core, wherein the magnetic core Comprises a first part adjacent to the gap and a second part other than the first part, wherein the cross-sectional area of the first part is greater than the cross-sectional area of the second part. The current sensor is characterized by being formed large.

  According to the current sensor of the present invention, the magnetic core has the first part adjacent to the gap and the second part other than the first part, and the cross-sectional area of the first part is It is formed larger than the cross-sectional area of the portion 2. Therefore, it is possible to reduce the size of the magnetic core as a whole without narrowing the region where the magnetic flux density is uniform in the gap of the magnetic core.

In the current sensor of the present invention, it is preferable that the magnetic core is formed by compressing or compressing a powder made of a magnetic material and then sintering.
According to such a configuration, it is possible to more easily manufacture magnetic cores having different cross-sectional sizes between the first portion and the second portion.

  ADVANTAGE OF THE INVENTION According to this invention, it is possible to provide the current sensor which can reduce a magnetic body core, without narrowing the area | region where the magnetic flux density in the gap of a magnetic body core is uniform.

2 is a perspective view of a current sensor according to Embodiment 1. FIG. It is a perspective view of the current sensor of Embodiment 2.

<Embodiment 1>
Hereinafter, Embodiment 1 of the present invention will be described in detail with reference to the drawings.
As shown in FIG. 1, a current sensor 10 according to the present embodiment includes a magnetic core 12 formed in a substantially C shape as a whole, and a magnetoelectric conversion element 16 disposed in a gap 14 of the magnetic core 12. It has.

  The magnetic core 12 is formed by punching a plate material made of a magnetic material such as permalloy in a substantially C shape. The overall shape of the magnetic core 12 is formed in a substantially “C” shape, and is arranged so as to surround the periphery of the metal bus bar 18 serving as a current path. In other words, the bus bar 18 is inserted through the central portion 13 of the magnetic core 12 formed in a substantially C shape. The bus bar 18 corresponds to the “conductor” of the present invention.

  A gap 14 having a predetermined size is formed in the magnetic core 12, and a magnetoelectric conversion element 16 such as a Hall element is disposed in the gap 14. The magnetic flux generated by the current E flowing through the bus bar 18 is focused on the magnetic core 12 and a magnetic field is generated in the gap 14 provided in the magnetic core 12. The magnitude of the current E flowing through the bus bar 18 can be detected by converting the strength of the magnetic field in the gap 14 into a voltage signal by the magnetoelectric conversion element 16. In FIG. 1, an amplifier circuit that amplifies the output voltage from the magnetoelectric conversion element 16 is omitted.

  As shown in FIG. 1, the magnetic core 12 includes a first portion 12a adjacent to the gap 14 and a second portion 12b other than the first portion 12a. The cross-sectional area of the first portion 12a is formed larger than the cross-sectional area of the second portion 12b. Here, the “cross-sectional area” means an area of a magnetic flux passing surface in each part of the magnetic core 12 formed in a substantially C shape.

  Moreover, since the magnetic core 12 is formed by punching a plate made of a magnetic material into a substantially C shape, the width dimension W11 of the first portion 12a is equal to the width dimension W12 of the second portion 12b. It is the same.

  By the way, in order to reduce the size of the magnetic core 12, it may be better to reduce the cross-sectional area of the magnetic core 12 formed in a substantially C shape over the entire circumference.

  However, when the cross-sectional area of the first portion 12a adjacent to the gap 14 is reduced, the region where the magnetic flux density is uniform in the gap 14 is narrowed. Therefore, the position of the magnetoelectric conversion element 16 disposed in the gap 14 Matching work becomes difficult.

  Therefore, in the current sensor 10 of the present embodiment, the cross-sectional area of the first portion 12a is formed larger than the cross-sectional area of the second portion 12b. As a result, the entire magnetic core 12 can be reduced in size without narrowing the region where the magnetic flux density is uniform in the gap 14 (that is, without reducing the area of the magnetic flux generation surface S1). .

  As described above, according to the current sensor 10 of the present embodiment, it is possible to reduce the size of the magnetic core 12 without narrowing the region where the magnetic flux density is uniform in the gap 14. Therefore, the current sensor 10 can be reduced in size, and as a result, the electrical connection box on which the current sensor 10 is mounted can be reduced in size.

<Embodiment 2>
Next, Embodiment 2 of the present invention will be described in detail with reference to the drawings.
In the present embodiment, the shape of the magnetic core is different from that of the first embodiment. Other configurations are substantially the same as those of the first embodiment, and the same configurations as those of the first embodiment are denoted by the same reference numerals and redundant description is omitted.

  As shown in FIG. 2, the current sensor 20 according to the present embodiment includes a magnetic core 22 formed in a substantially C shape as a whole, and a magnetoelectric conversion element 16 disposed in a gap 24 of the magnetic core 22. It has.

  Unlike the first embodiment, the magnetic core 22 is formed by compressing or compressing a powder made of a magnetic material such as permalloy or ferrite in a molding die and then sintering (so-called pressure). It is called a powder core). The entire shape of the magnetic core 22 is formed in a substantially “C” shape, and is disposed so as to surround the metal bus bar 18 serving as a current path. In other words, the bus bar 18 is inserted through the central portion 23 of the magnetic core 22 formed in a substantially C shape.

  A gap 24 having a predetermined size is formed in the magnetic core 22, and a magnetoelectric conversion element 16 such as a Hall element is disposed in the gap 24. The magnetic flux generated by the current E flowing through the bus bar 18 is focused on the magnetic core 22 and a magnetic field is generated in the gap 24 provided in the magnetic core 22. The magnitude of the current E flowing through the bus bar 18 can be detected by converting the strength of the magnetic field in the gap 24 into a voltage signal by the magnetoelectric conversion element 16. In FIG. 2, an amplifier circuit that amplifies the output voltage from the magnetoelectric conversion element 16 is omitted.

  As shown in FIG. 2, the magnetic core 22 includes a first portion 22a adjacent to the gap 24 and a second portion 22b other than the first portion 22a. The cross-sectional area of the first portion 22a is formed larger than the cross-sectional area of the second portion 22b.

  In addition, since the magnetic core 22 is formed by compressing or compressing a powder made of a magnetic material in a mold and then sintering, the magnetic core 22 is different from the first embodiment in that the first portion 22a is formed. It is possible to make the width dimension W21 different from the width dimension W22 of the second portion 22b.

  According to the current sensor 20 of the present embodiment, it is possible to make the width dimension W21 of the first portion 22a different from the width dimension W22 of the second portion 22b. Therefore, it is possible to more easily manufacture the magnetic core 22 having different cross-sectional shapes between the first portion 22a and the second portion 22b.

  Further, according to the current sensor 20 of the present embodiment, the cross-sectional area of the first portion 22a can be formed larger than the cross-sectional area of the second portion 22b. As a result, the entire magnetic core 22 can be reduced in size and the amount of material used without narrowing the region where the magnetic flux density is uniform in the gap 24 (that is, without reducing the area of the magnetic flux generation surface S2). It is possible to achieve a reduction in cost by reducing the number of current sensors, and to obtain a current sensor with higher accuracy than the shape adopted in the first embodiment.

  The magnetic core 22 can also be manufactured from a plate made of a magnetic material, and the cross-sectional area of the first portion 22a can be formed larger than the cross-sectional area of the second portion 22b. As a result, the entire magnetic core 22 can be reduced in size without narrowing the region where the magnetic flux density is uniform in the gap 24 (that is, without reducing the area of the magnetic flux generation surface S2). It is possible to obtain a current sensor with higher accuracy than the shape of the first embodiment.

  As described above, according to the current sensor 20 of the present embodiment, it is possible to reduce the size of the magnetic core 22 without narrowing the region where the magnetic flux density is uniform in the gap 24. Therefore, it is possible to achieve downsizing of the current sensor 20, and consequently downsizing of the electrical junction box.

DESCRIPTION OF SYMBOLS 10, 20 ... Current sensor 12, 22 ... Magnetic body core 12a, 22a ... 1st part 12b, 22b .... 2nd part 14, 24 ... Gap 16 ... Magnetoelectric conversion element 18 ... Bus bar (conductor)
E ... Current

Claims (2)

A current sensor for detecting a magnitude of a current flowing in a conductor inserted through the magnetic core by a magnetoelectric transducer disposed in a gap of the magnetic core;
The magnetic core includes a first portion adjacent to the gap and a second portion other than the first portion, and a cross-sectional area of the first portion is that of the second portion. A current sensor, wherein the current sensor is formed larger than a cross-sectional area.   2. The current sensor according to claim 1, wherein the magnetic core is formed by compressing or compressing a powder made of a magnetic material and then sintering the powder.

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