Current sensor

Abstract

Disclosed is a current sensor with which size and / or cost can be reduced while maintaining detection accuracy in an energization path through which a large current is supplied.　A current sensor 10 comprises: a bus bar 12 constituting an energization path; a pair of core members 18, 18 that, above the surface 14 on one side of the bus bar 12 with respect to the plate thickness direction, extend toward one side and the other side with respect to the plate width direction of the bus bar 12 and are disposed facing each other across a gap 16 provided in a central portion with respect to the plate width direction; and a magnetic detector 20 disposed in the gap 16 provided in the interval across which the pair of core members 18, 18 face each other. An extension end portion 22 of each of the core members 18 disposed on the outer side, with respect to the plate width direction, beyond side edge portions 24 of the bus bar 12 is bent toward the bus bar 12 side.

Description

Current Sensor

[0001] The present disclosure relates to a current sensor.

[0002] Patent Document 1 discloses a magnetic detection type current sensor mounted on vehicles such as electric vehicles and hybrid vehicles, which measures the value of the current flowing in the current path by detecting the amount of magnetic flux generated by the current flowing in the current path. In such a current sensor, in order to enable more accurate measurement of the current value, a gap core is arranged around the current path, where a gap is formed by cutting a part of a round or square wound core, and a Hall element, which is a magnetic detector, is inserted into the gap to detect the magnetic field.

[0003] JP 2013-113630 A

[0004] However, it was necessary to arrange a gap core around the current path so that it could surround the current path, which inevitably increased the size of the current sensor itself. In particular, with the increase in current in vehicles in recent years, the current path itself has become larger, and the gap core has also become larger to accommodate the current path, which has exacerbated the problem. Furthermore, to achieve high-precision magnetic field detection, it was necessary to use materials with good magnetic properties, such as electromagnetic steel sheet or permalloy, as the core material, and the increase in size due to the increase in current led to an unavoidable increase in cost.

[0005] Therefore, a current sensor is disclosed that can be made smaller and less expensive while maintaining detection accuracy in a current path through which a large current flows.

[0006] The current sensor of the present disclosure comprises a bus bar that forms a current path, a pair of core members that extend above one surface of the bus bar in the plate thickness direction toward one side and the other side of the bus bar in the plate width direction and are arranged opposite each other across a gap provided in the central part of the plate width direction, and a magnetic detector that is arranged in the gap provided in the opposing gap between the pair of core members, and the extending end portions of each of the core members that are arranged outward in the plate width direction beyond the side edges of the bus bar are bent toward the bus bar.

[0007] According to the current sensor of the present disclosure, it is possible to achieve miniaturization and cost reduction while maintaining detection accuracy in an electric path through which a large current flows.

[0008] Fig. 1 is a perspective view showing a current sensor according to a first embodiment mounted on a printed circuit board, Fig. 2 is a plan view of the current sensor shown in Fig. 1, and Fig. 3 is a cross-sectional view taken along line III-III in Fig. 2.

[0009] <Description of Embodiments of the Present Disclosure> First, embodiments of the present disclosure will be described. A current sensor of the present disclosure includes: (1) a bus bar that forms a current path; a pair of core members that extend above one surface of the bus bar in a plate thickness direction toward one and the other in a plate width direction of the bus bar and are arranged opposite each other across a gap provided in a central portion in the plate width direction; and a magnetic detector that is arranged in the gap provided in the opposing gap between the pair of core members, wherein an extending end portion of each of the core members that is arranged outward in the plate width direction beyond a side edge portion of the bus bar is bent toward the bus bar.

[0010] According to the current sensor of this aspect, a pair of core members are disposed on one side of the busbar in the thickness direction, forming a current path, and are disposed opposite each other across a gap in the width direction. This allows a magnetic detector to be disposed in the gap between the pair of core members on one side of the busbar in the thickness direction. Furthermore, the extending end of each core member, which is disposed outward in the width direction beyond the side edge of the busbar, is bent toward the busbar. This allows the pair of core members to exert a magnetic field collecting effect, and even if a core member is not disposed on the other side of the busbar in the thickness direction, magnetic field detection can be performed with high accuracy when the current passing through the busbar is in the high current range. Furthermore, the pair of core members of this aspect eliminates the need to dispose a core member on the other side of the busbar in the thickness direction. This allows for the core members themselves and the entire current sensor to be made smaller and with reduced material costs compared to conventional structures in which a gap core, which is formed by cutting a portion of a round or rectangular wound core around the current path, is disposed. In addition, when the current passing through the busbar is in the high-current range, the magnetic field can be detected with sufficient accuracy even if the pair of core members are made of a material such as iron. As a result, there is no need to use materials such as electromagnetic steel sheets or permalloy, and costs can be reduced. Therefore, the current sensor of this aspect can be made smaller and less expensive while maintaining detection accuracy in a current path through which a large current flows.

[0011] The current value passed through the bus bar of the current sensor of this embodiment is in the large current range, and can be applied to current values ​​in the range of approximately 100 A to 2000 A.

[0012] (2) In the above (1), it is preferable that the extending end of each core member protrudes downward beyond the surface of the other side of the bus bar in the plate thickness direction. Since the extending end of each core member protrudes downward beyond the bus bar, the magnetic collecting effect of the pair of core members is more effectively exerted, thereby improving the detection accuracy of the current sensor. Moreover, since there is no need to provide a core member that covers the bus bar from below and connects the extending ends of the pair of core members, it is possible to achieve a smaller size and lower costs compared to conventional structures.

[0013] (3) In the above (1) or (2), it is preferable that each of the core members is configured in an L-shape having a parallel portion extending parallel to the bus bar and the extending end portion bent in a direction perpendicular to the parallel portion. Since each of the core members arranged around the bus bar is configured in an L-shape with the parallel portion and the extending end portion perpendicularly connected, it is possible to improve the magnetic collection effect of the core members while miniaturizing the core members and the entire current sensor.

[0014] (4) In the above (3), it is preferable that the magnetic detector comprises a printed circuit board and a magnetic sensor mounted on a first surface of the printed circuit board, the magnetic sensor is arranged in the gap, while the parallel portion of each of the core members is placed on the first surface of the printed circuit board, the extended end of each of the core members protrudes downwardly below the second surface of the printed circuit board, the extended end of at least one of the core members is inserted through a through hole formed in the printed circuit board and protrudes downwardly below the second surface of the printed circuit board, and the bus bar is superimposed on the second surface of the printed circuit board.

[0015] By placing the parallel portions of the core members on the first surface of the printed circuit board, which is the mounting surface of the magnetic sensor, the magnetic sensor can be stably positioned in the gap between the pair of core members while holding each core member to the printed circuit board. The extended end of each core member protrudes downward from the second surface of the printed circuit board, and the bus bar is overlapped with the second surface of the printed circuit board. This reduces the overall height dimension of the current sensor (the dimension in the thickness direction of the bus bar and the printed circuit board) while improving the magnetic collection performance and assembly stability of the pair of core members. In addition, because the extended end of at least one core member passes through the through hole in the printed circuit board and protrudes downward from the second surface of the printed circuit board, the positioning and retention of the core member relative to the printed circuit board can be improved.

[0016] (5) In any one of (1) to (4) above, it is preferable that each of the core members is made of an iron-based material, because even if the core members are made of an iron-based material, magnetic field detection in a large current range can be performed with high accuracy, and further cost reduction can be achieved.

[0017] <Details of the embodiment of the present disclosure> Specific examples of the current sensor of the present disclosure will be described below with reference to the drawings. Note that the present disclosure is not limited to these examples, but is defined by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims.

[0018] First Embodiment A current sensor 10 according to a first embodiment of the present disclosure will be described below with reference to FIGS. 1 to 3. This current sensor 10 is provided in a junction box (electrical connection box) or the like inside a battery pack mounted in, for example, an electric vehicle or a hybrid vehicle, and measures the value of a current flowing through the junction box (JB). Note that the current sensor 10 can be positioned in any orientation within the vehicle; however, in the following description, the upper side will be referred to as the upper side in FIG. 3, the lower side as the lower side in FIG. 3, the left side as the upper side in FIG. 2, the right side as the lower side in FIG. 2, the front side as the left side in FIG. 2, and the rear side as the right side in FIG. 2. Note that, for multiple identical components, only some of the components will be designated by reference numerals, and the reference numerals may be omitted for the other components.

[0019] <Current sensor 10> The current sensor 10 includes a bus bar 12 that forms a current path, and a pair of core members 18, 18 that extend toward one side and the other in the width direction (left-right direction) of the bus bar 12 above a top surface 14, which is one surface in the thickness direction (up-down direction) of the bus bar 12, and are arranged opposite each other in the left-right direction across a gap 16 provided in the center of the width direction (left-right direction). In the current sensor 10, a magnetic detector 20 is arranged in the gap 16 provided in the gap between the pair of core members 18, 18.

[0020] <Busbar 12> The busbar 12 is disposed, for example, in a JB to form an electrical path, with both ends of the busbar 12 connected to electrical components in the JB, or one end of the busbar 12 exposed to the outside from the JB to be connected to an external electrical device, etc. The busbar 12 is formed, for example, from a metal such as copper (including copper alloy) that has excellent electrical conductivity. In the first embodiment, the busbar 12 has a substantially rectangular cross section and extends substantially straight in the front-to-rear direction.

[0021] <Core Member 18> As described above, each core member 18 extends outwardly toward one side and the other side in the width direction (left-right direction) of the bus bar 12, separated by the gap 16. Furthermore, in each core member 18, the extending portions extending outwardly toward one side and the other side in the left-right direction, that is, the extending end portions 22, are positioned beyond the side edge portions 24 of the bus bar 12 and outwardly of the side edge portions 24 in the left-right direction, and each extending end portion 22 is bent downwardly toward the bus bar 12 side.

[0022] In the first embodiment, the extending end portion 22 of each core member 18 protrudes downward from a lower surface 26, which is the surface on the other side in the thickness direction of the bus bar 12. More specifically, each core member 18 has a parallel portion 28 extending parallel to the bus bar 12. That is, the parallel portion 28 of each core member 18 extends in the horizontal direction (a direction perpendicular to the up-down direction) and extends outward in the left-right direction from a middle portion of the bus bar 12 in the left-right direction, as shown in the plan view of FIG. 2. Then, each extending end portion 22 bends downward and extends in a direction perpendicular to the parallel portion 28 from the outer left-right end of each parallel portion 28. As a result, as shown in the longitudinal cross section of FIG. 3, each core member 18 has a substantially L-shaped longitudinal cross section, and each core member 18 has a predetermined longitudinal dimension.

[0023] In particular, in the first embodiment, each parallel portion 28 and each extending end portion 22 are rectangular in plan view. Furthermore, each parallel portion 28 and each extending end portion 22 have the same front-to-rear dimension, and each extending end portion 22 has a smaller left-to-right dimension than each parallel portion 28. The height (vertical dimension) of each parallel portion 28 is not limited, but may be, for example, approximately equal to the height of a magnetic sensor 39 (described later) in the magnetic detector 20, or slightly greater than the height of the magnetic sensor 39. In other words, the upper end surface of each parallel portion 28 may be located slightly higher than the upper end surface of the magnetic sensor 39, for example.

[0024] In other words, a pair of extending end portions 22, 22 is provided on both lateral sides of the busbar 12, extending in a direction perpendicular to the lateral direction and laterally outward from both lateral edges 24, 24 of the busbar 12, and extends vertically in the longitudinal cross section shown in FIG. 3 . The upper ends of each extending end portion 22 are provided with parallel portions 28 extending inward in the lateral direction. Lateral inner faces 30 of each parallel portion 28 face each other across a predetermined distance D (see FIG. 3 ), and the gap between these lateral inner faces 30, 30 is the gap 16 provided in the central portion of the busbar 12 in the width direction (lateral direction) between the core members 18. In the first embodiment, the lateral inner faces 30 of each core member 18 are located laterally inward from both lateral edges 24, 24 of the busbar 12. That is, in a vertical projection, the side edge portions 24, 24 of the bus bar 12 partially overlap the parallel portions 28 of each core member 18 by a left-right dimension E (see FIG. 3).

[0025] In the first embodiment, the lower end surface 32 of each extending end portion 22 extends in a direction perpendicular to the up-down direction, and extends below and parallel to the lower surface 26 of the bus bar 12. In other words, the extending end portion 22 of each core member 18 does not bend inward in the left-right direction, for example, toward the bus bar 12, and the lower end of the extending end portion 22 of each core member 18 is open, and the bus bar 12 is exposed downward through a lower opening 34 formed by the lower end of each extending end portion 22. In other words, in the first embodiment, the lower portion of the bus bar 12 is not covered by each core member 18.

[0026] The material of each core member 18 having the above shape is not limited as long as it is a metal, but it is preferable that it be made of an inexpensive iron-based material. The iron-based material may be pure iron with a low carbon content, cast iron with a high carbon content, steel with an intermediate carbon content, or an iron alloy containing other elements such as nickel, chromium, or molybdenum. Each core member 18 may be formed by molding the above material into a predetermined shape, or may be made from scrap metal generated when forming other metal members, for example.

[0027] <Magnetic detector 20> As described above, the magnetic detector 20 is disposed in the gap 16 between each core member 18. In the first embodiment, the magnetic detector 20 includes a printed circuit board 36 and a magnetic sensor 39 mounted on an upper surface 38, which is a first surface of the printed circuit board 36. The magnetic sensor 39 in this magnetic detector 20 is disposed in the gap 16 between each core member 18 described above.

[0028] <Printed Circuit Board 36> The printed circuit board 36 extends horizontally, and an electric circuit (not shown) is printed on an upper surface 38 of the printed circuit board 36. The electric circuit and the magnetic sensor 39 are electrically connected to each other, thereby mounting the magnetic sensor 39. On both the left and right sides of the mounting location of the magnetic sensor 39 in the printed circuit board 36, through holes 40 are formed that penetrate the printed circuit board 36 in the thickness direction (up and down direction). Each through hole 40 is rectangular in plan view and is formed with a size that allows the extension end portion 22 of each core member 18 to be inserted therethrough.

[0029] Specifically, each through hole 40 has a front-to-rear dimension that is equal to or slightly smaller than each extending end portion 22, and a left-to-right dimension that is slightly larger than each extending end portion 22. This allows each extending end portion 22 of each core member 18 to be inserted into each through hole 40 from above, and each core member 18 is assembled to the printed circuit board 36 by inserting each extending end portion 22 into each through hole 40. When each core member 18 is assembled to the printed circuit board 36, the parallel portion 28 of each core member 18 rests on the first surface (top surface 38) of the printed circuit board 36. Furthermore, each extending end portion 22 inserted into each through hole 40 protrudes downward from the bottom surface 42, which is the second surface of the printed circuit board 36.

[0030] Furthermore, the bus bar 12 described above is disposed below the printed circuit board 36, and in the first embodiment, the second surface (lower surface 42) of the printed circuit board 36 and the upper surface 14 of the bus bar 12 are overlapped. The extending end portions 22 of the core members 18 inserted into the through holes 40 of the printed circuit board 36 protrude below the lower surface 26 of the bus bar 12, as described above.

[0031] It should be noted that a known substrate can be used as the printed circuit board 36. That is, the printed circuit board 36 may be a flexible substrate that is capable of flexibly deforming, or may be a rigid substrate that has a certain degree of deformation rigidity.

[0032] Furthermore, when each core member 18 is assembled to the printed circuit board 36, the method of fixing the printed circuit board 36 and each core member 18 is not limited, as long as each core member 18 does not slip out of the printed circuit board 36. That is, the parallel portions 28 of each overlapping core member 18 may be glued to the printed circuit board 36, or the front-to-rear dimensions of each extending end 22 and each through hole 40 may be equalized, and each extending end 22 may be press-fit into each through hole 40. Alternatively, when the current sensor 10 is placed in a JB (not shown), each core member 18 and the printed circuit board 36 may be fixed to the housing of the JB, or the core members 18 and the printed circuit board 36 may be fixed to each other via the housing of the JB.

[0033] <Magnetic Sensor 39> There are no limitations on the magnetic sensor 39, and any known magnetic sensor may be used as long as it is a magnetic field detection type. That is, the magnetic sensor 39 detects the current value by utilizing a magnetic field (magnetic field) generated by a current flowing through the bus bar 12, and may be a cored or coreless sensor, and specifically, a Hall IC or the like may be used.

[0034] In embodiment 1, the magnetic sensor 39 is arranged in the center of the gap 16 between each core member 18 in the left-right direction, and in particular in embodiment 1, the magnetic sensor 39 is located in the center part of the bus bar 12 in the plate width direction (left-right direction).

[0035] In the current sensor 10 described above, when a current flows through the busbar 12 in a direction from front to rear, a clockwise magnetic path R (shown by a two-dot chain line in FIG. 3 ) is formed around the busbar 12 in the longitudinal cross section of FIG. Here, core members 18 made of an iron-based material are disposed on both the left and right sides of the busbar 12, and magnetic field is collected by each core member 18, forming the magnetic path R in a ring shape along each core member 18. In particular, in the first embodiment, the current sensor 10 is intended to detect magnetic fields in a large current range, and a large current flowing through the busbar 12 can stably form the ring-shaped magnetic path R even when each core member 18 has a gap such as the lower opening 34 or the gap 16. This allows the magnetic sensor 39 disposed in the gap 16 of each core member 18 to detect a current value corresponding to the strength of the magnetic field.

[0036] The current sensor 10 according to the present disclosure is suitable for detecting magnetic fields in a large current range, and for example, the current value flowing through the bus bar 12 is preferably in the range of 100 A to 2000 A.

[0037] According to the current sensor 10 of the first embodiment having the above-described structure, the core members 18 are provided above the busbar 12, the magnetic sensors 39 of the magnetic detector 20 are disposed in the gaps 16 between the core members 18, and each core member 18 has an extending end portion 22 that extends downward outward in the left-right direction from the side edges 24, 24 of the busbar 12. In other words, the busbar 12 is covered on three sides (above, to the left, and to the right) by the core members 18. When a current in a high current range flows through the busbar 12, for example, the core members 18 exert a magnetic collecting effect, forming a circular magnetic path R along each core member 18. This allows the magnetic sensor 39 disposed in the gaps 16 between the core members 18 to detect the value of the current flowing through the busbar 12. In other words, to detect a current in a high current range, it is sufficient to provide relatively small core members 18 having the above-described shape around the busbar 12, which allows the current sensor 10 to be made smaller and less expensive than conventional structures.

[0038] The extending end portion 22 of each core member 18 protrudes downward below the lower surface 26 of the bus bar 12. This allows both side edge portions 24, 24 of the bus bar 12 to be covered from the outer left and right sides by the extending end portions 22, and a stable annular magnetic path R can be formed around the bus bar 12 when current is applied to the bus bar 12.

[0039] Each core member 18 is configured in an L-shape having a parallel portion 28 extending parallel to the bus bar 12 and an extending end portion 22 bent in a direction perpendicular to the parallel portion 28. This allows each core member 18 to stably cover the periphery of the bus bar 12 on three sides, and enables a more stable annular magnetic path R to be formed around the bus bar 12 when current is applied to the bus bar 12.

[0040] The printed circuit board 36 has through holes 40, and the extending end portion 22 of each core member 18 is inserted into each through hole 40, so that the parallel portion 28 of each core member 18 is superimposed on the upper surface 38 of the printed circuit board 36. In addition, the bus bar 12 is superimposed on the lower surface 42 of the printed circuit board 36, and each extending end portion 22 extends below the lower surface 26 of the bus bar 12. This allows the bus bar 12 and each core member 18 to be fixed via the printed circuit board 36, and allows the core members 18 to be positioned around the bus bar 12 with high precision.

[0041] Although there are no particular limitations on the materials for the core members 18 as long as they are magnetic, it is preferable that they be made of an inexpensive iron-based material. In particular, since the core members 18 are relatively small, it is possible to use scrap metal generated when forming other metal members. This allows for cost reduction compared to using electromagnetic steel sheets, permalloy, etc.

[0042] <Modifications> Although the first embodiment has been described above in detail as a specific example of the present disclosure, the present disclosure is not limited to this specific description. Modifications, improvements, etc. within the scope that can achieve the object of the present disclosure are included in the present disclosure. For example, the following modifications of the embodiment are also included in the technical scope of the present disclosure.

[0043] (1) The extension dimension (vertical dimension) of the extension end portion is not limited. In the above embodiment, the lower end surface 32 of each extension end portion 22 is located below the lower surface 26 of the bus bar 12, but it may be located above the lower surface of the bus bar. Note that it is preferable for the extension end portion to have a certain degree of extension dimension, and for example, it is desirable for the lower end surface of the extension end portion to be located below the lower surface of the printed circuit board.

[0044] (2) In the above embodiment, each extending end 22 extends straight in the up-down direction. However, the lower end of each extending end may have a portion that protrudes inward in the left-right direction. In this case, the inner surface of the protruding portion at the lower end of the extending end is preferably located outward in the left-right direction from the side edge of the bus bar. Even if the lower end of the extending end has a portion that protrudes inward in the left-right direction, it is preferable that the portion does not cover the bus bar but is open downward. Note that even in the above-described case, by forming a through hole in the printed circuit board larger in size than the lower end surface of the extending end in a plan view, each core member can be assembled to the printed circuit board from above.

[0045] (3) In the above embodiment, the magnetic sensor 39 was provided in the central portion of the bus bar 12 in the plate width direction (left-right direction). However, the magnetic sensor may be positioned inside the gap, offset to some extent to one side in the left-right direction from the central portion of the bus bar in the plate width direction.

[0046] (4) In the above embodiment, a pair of through holes 40, 40 are provided on both the left and right sides of the mounting location of the magnetic sensor 39 on the printed circuit board 36, and the extending end portion 22 of each core member 18 is inserted through the through holes 40, 40. However, this is not limited to this. For example, the extending end portion of at least one core member does not have to be inserted through a through hole in the printed circuit board, and may extend vertically outward in the left-right direction beyond the left-right ends of the printed circuit board.

[0047] (5) In the above embodiment, the printed circuit board 36 is placed on the upper surface 14 of the bus bar 12, and the magnetic sensor 39 and each core member 18 are placed on top of the printed circuit board 36. However, this is not limited to this. The current sensor 10 of embodiment 1 may be configured upside down, or the printed circuit board may be placed on the lower surface of the bus bar, and the magnetic sensor and each core member may be placed on top of the printed circuit board. Note that the members that are placed on top of each other are not limited to being placed on top of each other directly, and may be placed on top of each other indirectly via a separate member such as a spacer.

[0048] 10 Current sensor 12 Bus bar 14 Upper surface (one side surface in the thickness direction of the bus bar) 16 Gap 18 Core member 20 Magnetic detector 22 Extended end portion 24 Side edge portion 26 Lower surface (other side surface in the thickness direction of the bus bar) 28 Parallel portion 30 Inner surface in the left-right direction 32 Lower end surface 34 Lower opening 36 Printed circuit board 38 Upper surface (first surface) 39 Magnetic sensor 40 Through hole 42 Lower surface (second surface) R Magnetic path

Claims

1. A current sensor comprising: a bus bar constituting an energization path; a pair of core members extending upward above one surface in the plate thickness direction of the bus bar, facing each other with a gap provided in a central portion in the plate width direction, across the gap; and a magnetic detector disposed in the gap provided in the facing gap between the pair of core members, wherein extending end portions of the respective core members disposed outward in the plate width direction beyond side edge portions of the bus bar are bent toward the bus bar side.

2. The current sensor according to claim 1, wherein the extending end portions of the respective core members protrude below a surface on the other side in the plate thickness direction of the bus bar.

3. The current sensor according to claim 1 or 2, wherein each of the core members is configured in an L shape having a parallel portion extending parallel to the bus bar and the extending end portion bent in a direction orthogonal to the parallel portion.

4. The magnetic detector includes a printed circuit board and a magnetic sensor mounted on a first surface of the printed circuit board. The magnetic sensor is disposed in the gap, while the parallel portions of the respective core members are placed on the first surface of the printed circuit board, and the extending end portions of the respective core members protrude below a second surface of the printed circuit board. The extending end portion of at least one of the core members protrudes below the second surface of the printed circuit board through a through hole formed through the printed circuit board, and the bus bar is overlapped with the second surface of the printed circuit board. The current sensor according to claim 3.

5. The current sensor according to claim 1 or 2, wherein each of the core members is formed of an iron-based material.

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