JP6471826B1 - Current sensor and method of manufacturing bus bar used therefor - Google Patents

Abstract

In a current sensor capable of measuring a large current by diverting a current to be measured flowing through a bus bar, the number of parts is reduced and a measurement error due to manufacturing variation is reduced.
A current sensor according to the present invention includes a bus bar 10 through which a current I to be measured flows and a magnetic sensor that detects a magnetic field generated from the bus bar 10. The bus bar 10 is made of a metal plate having detection wiring portions 11A and 11B through which currents Id _A and Id _B flow and branch wiring portions 12A and 12B through which currents Ib _A and Ib _B flow. As for the metal plate which comprises the bus-bar 10, the detection wiring part 11A and the detection wiring part 11B are facing each other. According to the present invention, since the bus bar 10 is made of a metal plate, it is possible to reduce the number of parts and measurement errors due to manufacturing variations.
[Selection] Figure 2

Description

  The present invention relates to a current sensor and a method for manufacturing a bus bar used therefor, and more particularly to a current sensor suitable for measuring a large current and a method for manufacturing a bus bar used therefor.

  The current sensor is generally of a type in which a magnetic field generated by a current to be measured is detected by a magnetic sensor. For example, Patent Document 1 discloses a type of current sensor in which a sub bus bar is connected in parallel to a bus bar through which a measurement target current flows, and a magnetic field generated by the current flowing through the sub bus bar is detected by a magnetic sensor.

  Since the current sensor described in Patent Document 1 has a sub-bus bar connected in parallel to the bus bar and a magnetic sensor is assigned to the sub-bus bar, even if the current to be measured flowing through the bus bar is a large current, the current flowing through the sub-bus bar Since the amount is suppressed, it is suitable for measuring a large current.

JP 2007-212307 A

  However, the current sensor described in Patent Document 1 has a configuration in which the bus bar and the sub bus bar are separate parts, and both are fixed using rivets. There was also a problem that the measurement error caused by this was large.

  Accordingly, an object of the present invention is to reduce the number of parts and a measurement error due to manufacturing variations in a current sensor that enables measurement of a large current by diverting a current to be measured flowing through a bus bar. To do. Moreover, an object of this invention is to provide the manufacturing method of the bus bar used for such a current sensor.

  A current sensor according to the present invention includes a bus bar through which a current to be measured flows and a magnetic sensor that detects a magnetic field generated from the bus bar. The bus bar includes a first detection wiring section through which a part of the current to be measured flows, and a measurement target. The magnetic sensor is a measurement object that flows through the first detection wiring portion, and includes a second detection wiring portion in which another part of the current flows and a branch wiring portion in which the remaining portion of the current to be measured flows. A magnetic field generated by a part of the current and another part of the current to be measured flowing in the second detection wiring part is detected, and the first detection wiring part has a first part of the current to be measured flowing in the opposite direction. 1st and 2nd part, and the 3rd part which connects the 1st part and the 2nd part, and the 2nd detection wiring part has another part of current to be measured flowing in the direction opposite to each other. Connect the 4th and 5th parts with the 4th and 5th parts The metal plate which has 6 parts, and constitutes the bus bar, the first part and the fourth part face each other, the second part and the fifth part face each other, the third part and the sixth part Are characterized by facing each other.

  According to the present invention, the first detection wiring portion has a detour structure including the first to third portions, and the second detection wiring portion includes a detour structure including the fourth to sixth portions. Therefore, the amount of current flowing through the first and second detection wiring portions is reduced. As a result, a large current can be measured. In addition, since the bus bar is made of a metal plate, the number of parts can be reduced, and measurement errors due to manufacturing variations can be reduced.

  In the present invention, the bus bar is composed of a single metal plate, and the single metal plate constituting the bus bar has a first portion and a fourth portion facing each other, and a second portion and a fifth portion facing each other. The third portion and the sixth portion may be bent so as to face each other. According to this, since the bus bar is made of a single metal plate, the number of parts can be further reduced, and the measurement error due to manufacturing variations can be further reduced.

  In the present invention, the bus bar includes an input wiring portion connected to one end of the first detection wiring portion, one end of the second detection wiring portion, and one end of the branch wiring portion, the other end of the first detection wiring portion, And an output wiring portion connected to the other end of the second detection wiring portion and the other end of the branch wiring portion, and the first and second detection wiring portions are provided on the main surface of the input wiring portion and the output wiring portion. Alternatively, it may be bent vertically. According to this, a bus bar can be easily produced by bending a single metal plate at two locations.

  In the present embodiment, the first and second detection wiring portions may have a longer current path than the branch wiring portion. According to this, the amount of current flowing through the first and second detection wiring portions can be further reduced. In this case, the first detection wiring part, the second detection wiring part, and the branch wiring part may have the same cross-sectional shape perpendicular to the direction in which the current to be measured flows. According to this, since the difference in the amount of heat generated due to the difference in the length of the current path is offset by the difference in the heat capacity, it is possible to reduce the measurement error due to the temperature difference of the bus bar.

  A bus bar manufacturing method according to the present invention is a bus bar manufacturing method used for a current sensor, and by processing a metal plate, an input wiring portion, an output wiring portion, one end is connected to the input wiring portion, and the other end Producing a precursor having first and second detection wiring portions connected to the output wiring portion, and a branch wiring portion having one end connected to the input wiring portion and the other end connected to the output wiring portion, The precursor is bent so that the first detection wiring portion and the second detection wiring portion face each other.

  According to the present invention, the precursor is cut out from a single metal plate and the bus bar is produced by bending the precursor, so that the number of parts is reduced and the manufacturing variation is also reduced. As a result, it is possible to reduce measurement errors due to manufacturing variations.

  As described above, according to the present invention, in the current sensor capable of measuring a large current by diverting the current to be measured flowing through the bus bar, the number of parts is reduced and the measurement error due to the manufacturing variation is reduced. It becomes possible. Moreover, according to this invention, it becomes possible to provide the manufacturing method of the bus bar used for such a current sensor.

FIG. 1 is a schematic perspective view showing an appearance of a current sensor according to a preferred embodiment of the present invention. FIG. 2 is a schematic perspective view for explaining the shape of the bus bar 10. FIG. 3 is a schematic perspective view showing the appearance of the precursor 10A before the bus bar 10 is bent. FIG. 4 is a schematic side view of the bus bar 10 as viewed from the y direction. FIG. 5 is a schematic diagram for explaining the direction of the magnetic flux applied to the region A. FIG. FIG. 6 is a schematic diagram showing an example in which the magnetic sensor 40 having the magnetic core 41 is arranged in the region A.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a schematic perspective view showing an appearance of a current sensor according to a preferred embodiment of the present invention.

  As shown in FIG. 1, the current sensor according to the present embodiment includes a bus bar 10 through which a measurement target current I flows, a case 20 attached to the bus bar 10, and a magnetic sensor 40 accommodated in the case 20. . The bus bar 10 is a metal plate made of a good conductor such as copper (Cu), and is manufactured by bending a metal plate having a constant thickness. The type of the magnetic sensor 40 is not particularly limited, and a fluxgate sensor, an MI (magnetic impedance) sensor, a Hall sensor, an AMR sensor, a GMR sensor, a TMR sensor, or the like can be used. The case 20 may itself be a magnetic core.

  FIG. 2 is a schematic perspective view for explaining the shape of the bus bar 10.

As shown in FIG. 2, the bus bar 10 is made of a single metal plate, and is provided between the input wiring portion 13 and the output wiring portion 14 whose main surface is the xy plane, and between the input wiring portion 13 and the output wiring portion 14. Detection wiring portions 11A and 11B and branch wiring portions 12A and 12B. The detection wiring portions 11A and 11B and the branch wiring portions 12A and 12B are connected in parallel. Therefore, when the measurement target current I flows from the input wiring portion 13 to the output wiring portion 14, a part of the measurement target current I is obtained. A certain current Id _A flows through the detection wiring portion 11A, and a current Id _B that is another part of the measurement target current I flows through the detection wiring portion 11B, and currents Ib _A and Ib _B that are the remaining portions of the measurement target current I. Flows through the branch wiring portions 12A and 12B, respectively. Therefore, I = Id _A + Id _B + Ib _A + Ib _B.

Detection wiring portion 11A includes first and second portions ₁₁ 1, 11 ₂ extending in the z-direction, and a third portion 11 ₃ which extends in the x-direction, the current Id _A is a first portion 11 ₁ , the third portion 11 _3, and the second portion 11 ₂ flow in this order. Therefore, the direction of the current Id _A flowing in the first portion 11 _1, the direction of the current Id _A flowing through the second portion 11 ₂ are opposite to each other. Similarly, detection interconnect unit 11B includes a fourth and fifth portions ₁₁ 4, 11 ₅ which extends in the z-direction, made from the portion 11 ₆ of the sixth extending in x-direction, the current Id _B is a 4 parts 11 _4, flows in the order of the sixth portion 11 ₆ and the fifth portion 11 ₅ of the. Therefore, the direction of current Id _B flowing through the fourth portion 11 _4, the direction of the current Id _B flowing to the portion 11 ₅ of the fifth is opposite to each other. The detection wiring portion 11A, 11B has a first portion 11 ₁ and confronts the fourth portion 11 ₄ is another, second portion 11 ₂ and the fifth portion 11 ₅ face one another, the third portion 11 ₃ When a sixth portion 11 ₆ face each other as are bent perpendicular to the xy plane.

On the other hand, the two branch wiring parts 12A and 12B both have a linear shape extending in the x direction. Therefore, the length of the current path is longer in the detection wiring portions 11A and 11B than in the branch wiring portions 12A and 12B. Thereby, the current Id _A + Id _B flowing through the detection wiring portions 11A and 11B is further reduced. In the present embodiment, the two branch wiring portions 12A and 12B are provided in parallel. However, the number of branch wiring portions is not limited to two, and three or more branch wiring portions may be provided in parallel. .

  Although not particularly limited, in the present embodiment, the thicknesses and conductor widths of the detection wiring portions 11A and 11B and the branch wiring portions 12A and 12B are constant. Therefore, the cross-sectional shapes perpendicular to the current direction of the detection wiring portions 11A and 11B and the branch wiring portions 12A and 12B are equal to each other.

  FIG. 3 is a schematic perspective view showing the appearance of the precursor 10A before the bus bar 10 is bent.

  As shown in FIG. 3, the precursor 10 </ b> A before the bus bar 10 is bent is cut from a metal plate having a constant thickness in the z direction. For example, a metal plate made of copper (Cu) or the like having a constant thickness is prepared, and punching is performed on the metal plate, thereby detecting wiring portions 11A and 11B, branch wiring portions 12A and 12B, and an input wiring portion. 13, the precursor 10A including the output wiring portion 14, the common wiring portions 15 and 16, and the connection portions 17 and 18 can be manufactured in one step. In the punching process for a metal plate, if the thickness and the processing width of the metal plate are different depending on the planar position, the punching conditions are different depending on the planar position, so that it is difficult to process the shape as designed. On the other hand, the precursor 10A shown in FIG. 3 is high because the thickness of the metal plate used is constant and the processing widths of the detection wiring portions 11A and 11B and the branch wiring portions 12A and 12B are constant. Processing accuracy can be ensured. As a result, it is possible to reduce measurement errors due to variations in processing accuracy.

  After producing such a precursor 10A, the detection wiring part 11A is bent about 90 ° at the bending position B1 shown in FIG. 10 is completed. The bending positions B1 and B2 are both located on the common wiring parts 15 and 16, the bending position B1 is on one side when viewed from the connection parts 17 and 18, and the bending position B2 is on the other side when viewed from the connection parts 17 and 18. To position. Although not particularly limited, the conductor widths of the common wiring portions 15 and 16 and the connection portions 17 and 18 are the same as those of the detection wiring portions 11A and 11B and the branch wiring portions 12A and 12B in order to increase processing accuracy. It is preferable that

  FIG. 4 is a schematic side view of the bus bar 10 as viewed from the y direction.

  As shown in FIG. 4, when the bus bar 10 is viewed from the y direction, the detection wiring portion 11A and the detection wiring portion 11B are completely overlapped, and the branch wiring portion 12A and the branch wiring portion 12B are completely overlapped. The magnetic sensor 40 shown in FIG. 1 is disposed in a region A surrounded by the detection wiring portions 11A and 11B and the branch wiring portions 12A and 12B.

When the magnetic sensor 40 is arranged in the region A, as shown in FIG. 5, which is a schematic diagram, a magnetic flux in the same direction is applied to the region A by currents Id _A and Id _B flowing through the detection wiring portions 11A and 11B. In the example shown in FIG. 5, the first portion 11 ₁ and the fourth portion 11 ₄ to flow a current _Id A detection wiring portion 11B, the magnetic flux φ1 counterclockwise by Id _B of the detection wiring portion 11A is generated, the detection because second portion 11 ₂ and the fifth portion 11 ₅ to flowing current _Id a detection wiring portion 11B of the wiring portion 11A, the magnetic flux φ2 clockwise by Id _B is generated, the direction of the magnetic flux applied to the area a Are both in the y direction. Therefore, if the magnetic sensor 40 is disposed in the region A and the magnetic sensor 40 detects the strength of the magnetic field in the y direction, the total value of the currents Id _A and Id _B flowing in the detection wiring portions 11A and 11B can be detected. It becomes. Since the shunt ratio between the currents Id _A and Id _B flowing in the detection wiring portions 11A and 11B and the currents Ib _A and Ib _B flowing in the branch wiring portions 12A and 12B is known, the detection of the currents Id _A and Id _B The measurement target current I can be calculated based on the value.

  As shown in FIG. 6, the magnetic sensor 40 may include a magnetic core 41. In the example shown in FIG. 6, an annular magnetic core 41 opened in the z direction is used, and the detection wiring portions 11 </ b> A and 11 </ b> B, the saturable magnetic body M, and the detection wound around the periphery are surrounded by the magnetic core 41. Coil C is arranged. That is, such a configuration can be obtained when the case 20 itself shown in FIG. If such a magnetic core 41 is used, the disturbance magnetic field bypasses the magnetic core 41, so that the influence of the disturbance magnetic field can be reduced.

As described above, in the present embodiment, the bus bar 10 through which the current I to be measured flows is made of a single metal plate and is manufactured by bending it, so that the number of parts can be reduced. It is possible to produce almost no manufacturing variation. For this reason, it is possible to reduce measurement errors due to manufacturing variations. Further, since the detection wiring portions 11A and 11B have a longer current path than the branch wiring portions 12A and 12B, the currents Id _A and Id _B flowing through the detection wiring portions 11A and 11B can be reduced.

  Here, the bus bar 10 according to the present embodiment reduces the resistance value by using the two detection wiring portions 11A and 11B and the two branch wiring portions 12A and 12B on the assumption that a large current flows. The same resistance value as that of the present embodiment can be obtained by cutting out a bus bar composed of one detection wiring part and one branch wiring part using a metal plate having twice the thickness. In this case, the thickness of the metal plate Since the thickness becomes thicker, the machining accuracy during punching is reduced. Compared to this, in the present embodiment, the thickness of the metal plate is halved, so that it is possible to increase the processing accuracy during punching. Moreover, since the metal plate is thin, measurement errors due to the skin effect when a high-frequency current flows are also suppressed. In addition, this embodiment and the resistance value can also be obtained by cutting out two bus bars composed of one detection wiring part and one branch wiring part using a metal plate having the same thickness, and stacking them. As the number of parts increases and contact resistance occurs, the reliability of the product decreases.

  On the other hand, in this embodiment, since the bus bar 10 is produced by cutting out the precursor 10A from the metal plate and bending it, the bus bar 10 having a low resistance value is produced with high processing accuracy. Is possible. As a result, measurement errors due to variations in processing accuracy are reduced, and the number of parts is also reduced. Furthermore, if the cross-sectional shapes of the detection wiring portions 11A and 11B and the branch wiring portions 12A and 12B are made to coincide with each other, the processing accuracy is further improved.

In addition, when the cross-sectional shapes of the detection wiring portions 11A and 11B and the branch wiring portions 12A and 12B are constant, the length of each of the branch wiring portions 12A and 12B is L, and the length of each of the detection wiring portions 11A and 11B is If kL, the ratio of the resistance values of the detection wiring portion 11A, the detection wiring portion 11B, the branch wiring portion 12A, and the branch wiring portion 12B is k: k: 1: 1, and therefore the current Id _A that flows through the detection wiring portion 11A. The ratio of the current Id _B flowing through the detection wiring portion 11B, the current Ib _A flowing through the branch wiring portion 12A, and the current Ib _A flowing through the branch wiring portion 12A is 1: 1: k: k. And since detection wiring part 11A, 11B and branch wiring part 12A, 12B have the mutually same cross-sectional area, the emitted-heat amount in detection wiring part 11A, detection wiring part 11B, branch wiring part 12A, and branch wiring part 12B The ratio is also 1: 1: k: k.

  Here, the detection wiring parts 11A and 11B have a length k times that of the branch wiring parts 12A and 12B, and the detection wiring parts 11A and 11B and the branch wiring parts 12A and 12B are the same as each other. Since it has an area, the volume of the detection wiring part 11A, the detection wiring part 11B, the branch wiring part 12A, and the branch wiring part 12B, that is, the ratio of the heat capacity is k: k: 1: 1. This means that the branch wiring portions 12A and 12B release heat k times faster than the detection wiring portions 11A and 11B. That is, since the branch wiring portions 12A and 12B release heat k times faster than the detection wiring portions 11A and 11B, respectively, the detection wiring portions 11A and 11B and the branch wiring portion 12A. , 12B hardly causes a temperature difference. As a result, since the change in resistance value due to the temperature difference is suppressed, the current I to be measured can be shunted as designed, and the measurement error due to the temperature difference can be reduced.

  The preferred embodiments of the present invention have been described above, but the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention. Needless to say, it is included in the range.

  For example, in the above embodiment, the precursor 10A is cut out from a single metal plate, and the bus bar 10 is produced by bending the precursor 10A. However, a part of the bus bar 10 is the same or different metal plate. Alternatively, the bus bar 10 may be manufactured by using a separate member cut out from the substrate and joining the separated member to the precursor 10A. When another member that constitutes a part of the bus bar 10 is formed from a single metal plate, it can be punched at a time and the thickness is the same, which is preferable.

DESCRIPTION OF SYMBOLS 10 Busbar 10A Precursor 11A, 11B Detection wiring part 11 ₁ 1st part 11 ₂ 2nd part 11 ₃ 3rd part 11 ₄ 4th part 11 ₅ 5th part 11 ₆ 6th part 12A, 12B Branch wiring portion 13 Input wiring portion 14 Output wiring portions 15 and 16 Common wiring portions 17 and 18 Connection portion 20 Case 40 Magnetic sensor 41 Magnetic core A Regions B1 and B2 Bending position C Detection coil I Current to be measured M Saturable magnetic body φ1 , Φ2 magnetic flux

Claims (6)

A bus bar through which the current to be measured flows,
A magnetic sensor for detecting a magnetic field generated from the bus bar,
In the bus bar, a first detection wiring part through which a part of the measurement target current flows, a second detection wiring part through which another part of the measurement target current flows, and a remaining part of the measurement target current flow. It consists of a metal plate with a branch wiring part,
The magnetic sensor detects a magnetic field generated by the part of the measurement target current flowing in the first detection wiring part and the another part of the measurement target current flowing in the second detection wiring part;
The first detection wiring portion includes a first portion and a second portion in which the part of the current to be measured flows in opposite directions, and a third portion connecting the first portion and the second portion. Have
The second detection wiring portion includes fourth and fifth portions in which the other part of the current to be measured flows in directions opposite to each other, and a sixth portion connecting the fourth portion and the fifth portion. Has a part,
The metal plate constituting the bus bar has the first portion and the fourth portion facing each other, the second portion and the fifth portion facing each other, the third portion and the sixth portion. Current sensors characterized by the fact that they face each other.   The bus bar is made of a single metal plate, and the single metal plate constituting the bus bar has the first portion and the fourth portion facing each other, and the second portion and the fifth portion. 2. The current sensor according to claim 1, wherein the first portion and the sixth portion are bent so as to face each other. The bus bar includes one end of the first detection wiring unit, one end of the second detection wiring unit, an input wiring unit connected to one end of the branch wiring unit, and the other end of the first detection wiring unit, An output wiring portion connected to the other end of the second detection wiring portion and the other end of the branch wiring portion;
3. The current sensor according to claim 2, wherein the first and second detection wiring portions are bent perpendicularly to main surfaces of the input wiring portion and the output wiring portion.   4. The current sensor according to claim 1, wherein the first and second detection wiring portions have a longer current path than the branch wiring portion. 5.   5. The current according to claim 4, wherein the first detection wiring unit, the second detection wiring unit, and the branch wiring unit have the same cross-sectional shape perpendicular to the direction in which the current to be measured flows. Sensor.   A method of manufacturing a bus bar used for a current sensor, wherein an input wiring portion, an output wiring portion, and one end are connected to the input wiring portion and the other end is connected to the output wiring portion by processing a metal plate. A precursor having the first and second detection wiring portions, and a branch wiring portion having one end connected to the input wiring portion and the other end connected to the output wiring portion is manufactured, and the first detection A method of manufacturing a bus bar, comprising bending the precursor so that a wiring portion and the second detection wiring portion face each other.

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