JP2014010012A - Current sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the increase of hysteresis even when a core through-hole through which a conductive member is passed is enlarged.SOLUTION: A core 10 is formed by bending a plate. Projections 106 are formed by half-blanking at a pair of opposing pieces 102 arranged oppositely to each other at both ends of the core 10. A hall element 120 is disposed between the projections 106. By forming the projections 106 to reduce a core gap sectional area, a permeance coefficient is lowered to reduce hysteresis. Thus, the increase of hysteresis when a through-hole 108 is enlarged is canceled.

Description

  The present invention relates to a current sensor that detects a current flowing through a conductive member.

  In a conventional current sensor, a core piece having a predetermined shape is formed by shearing a plate material, and a plurality of core pieces are stacked and integrated to form a core. A through hole through which the conductive member is passed is formed in the core (see, for example, Patent Document 1).

  Further, when the current sensor is mounted on a vehicle, for example, a bus bar as a conductive member is inserted into the through hole. One end side of the bus bar is fitted to a battery terminal, and the other end side of the bus bar is fastened with a terminal that is caulked and coupled to an end portion of the harness (see, for example, Patent Document 2).

JP 2005-308526 A JP 2001-272422 A

  However, permalloy, which is an expensive soft magnetic material, is used as the material for the core piece, and the material for the through hole is a waste material, so it is necessary to design with the through hole as small as possible from the viewpoint of reducing material costs. was there.

  When a current sensor having a small through hole is mounted on a vehicle, for example, the portion of the bus bar that fits into the battery terminal cannot pass through the through hole. The terminal and the bus bar that are caulked to the harness are fastened with screws.

  In this case, since a screw that fastens the terminal and the bus bar that are caulked to the harness is required, the number of parts is increased and the reliability of screw fastening is required.

  On the other hand, when the through-hole is simply enlarged so that the part fitted to the battery terminal in the bus bar can pass, the material cost increases due to the increase in waste material, and the magnetic path length of the core becomes longer, so the hysteresis increases. Thus, there arises a problem that the current detection accuracy deteriorates.

  In view of the above points, an object of the present invention is to make it possible to suppress an increase in hysteresis even if a through hole is enlarged.

  In order to achieve the above object, according to the first aspect of the present invention, there is provided a current sensor that includes a core (10) and a Hall element (120, 120a) and detects a current flowing through the conductive member (3). The plate body is formed in an annular shape by bending, and the core body portion (100) in which the through hole (108) through which the conductive member is passed is formed, and is formed at both ends of the core body portion so as to face each other. A pair of opposed pieces (102) and a pair of protrusions (106, 106a) formed on the opposed pieces and arranged opposite to each other, wherein the Hall element is arranged between the protrusions. To do.

  According to this, by providing a protrusion and reducing the core gap cross-sectional area, the permeance coefficient is reduced and the hysteresis is reduced. Therefore, the increase in hysteresis due to the increase in the magnetic path length of the core when the through hole is enlarged is offset, and the increase in hysteresis can be suppressed even if the through hole is enlarged.

  In addition, the code | symbol in the bracket | parenthesis of each means described in this column and the claim shows the correspondence with the specific means as described in embodiment mentioned later.

1 is an exploded perspective view of a current sensor according to a first embodiment of the present invention. It is a perspective view of the current sensor of FIG. It is a perspective view of the current sensor of FIG. It is a top view of the core and Hall element of FIG. It is a perspective view which shows the use condition of the current sensor of FIG. It is a perspective view which shows the assembly | attachment state of the current sensor and bus bar of FIG. It is sectional drawing which shows the fitting part of the current sensor of FIG. 5, and a bus bar. FIG. 6 is a perspective view of the bus bar of FIG. 5. It is a perspective view of the core and Hall element in a current sensor concerning a 2nd embodiment of the present invention. It is a figure which shows the relationship between the board width of the core in the current sensor which concerns on 2nd Embodiment, and the magnetic flux density of a core gap part. It is a perspective view of the opposing piece of a core and Hall element in a current sensor concerning a 3rd embodiment of the present invention. It is a front view of the opposing piece core and Hall element of the core of FIG. It is a top view of the opposing piece core and Hall element of the core of FIG. It is a figure which shows the relationship between the presence or absence of a projection part in the current sensor which concerns on 3rd Embodiment, and the magnetic flux density of a core gap part.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiments, the same or equivalent parts are denoted by the same reference numerals in the drawings.

(First embodiment)
As shown in FIG. 5, the current sensor 1 of the present embodiment detects a current flowing from a battery 2 mounted on the vehicle to a vehicle electrical component (not shown) through a bus bar 3 and a harness (not shown). Used for. .

  As shown in FIGS. 1 to 4, the current sensor 1 includes a core 10, a circuit board 12, a housing 14, and the like.

  A Hall element 120 is mounted on the circuit board 12, and a plurality of various electronic components constituting a drive control circuit for the Hall element 120 are mounted. In the Hall element 120, a sensor chip 1200 is molded in a mold layer 1201 made of a mold resin.

  The core 10 is formed by bending a single plate material made of a conductive magnetic material (for example, permalloy). The core 10 includes a core main body 100 formed in a circular ring shape, and a pair of facing pieces 102 formed at both ends of the core main body 100 and arranged to face each other in parallel.

  A core gap 104 is formed between the pair of opposed pieces 102. Each of the opposing pieces 102 is formed with a cylindrical protrusion 106 at an opposing position. The protrusion 106 is formed by half-cutting.

  A Hall element 120 is disposed between the protrusions 106. More specifically, the entire sensor chip 1200 is located between the protrusions 106. The surface of the protrusion 106 that faces the Hall element 120 is a flat surface. In addition, the area of the surface of the protrusion 106 that faces the Hall element 120 is larger than the area of the surface of the sensor chip 1200 that faces the protrusion 106. Inside the core body 100, a core through hole 108 through which the bus bar 3 passes is formed.

The casing 14 is made of synthetic resin, and is formed with a cylindrical core housing portion 142 in which an annular core housing space 140 in which the core 10 is housed is formed, and a substantially rectangular parallelepiped circuit board housing space 144 in which the circuit board 12 is housed. A substantially box-shaped circuit board housing portion 146 and a cylindrical connector mounting portion 148 are provided. In addition, a housing through hole 150 through which the bus bar 3 is passed is formed inside the core housing part 142. The core 10 is housed in the core housing space 140, and the circuit board is housed in the circuit board housing space 144. 12 is accommodated, the core accommodating space 140 and the circuit board accommodating space 144 are filled with the sealing material 152 (the hatched portion in FIG. 2), and the core 10 and the circuit board 12 are sealed by the curing of the sealing material 152. Has been.

  The connector mounting portion 148 is connected to the side of the circuit board housing portion 146, and a connector terminal (not shown) provided in the connector mounting portion 148 and an electronic component of the circuit board 12 are connected via a wiring material. Yes.

  As shown in FIGS. 3 and 7, the housing 14 includes a bus bar insertion portion 156 formed with a bus bar insertion groove 154 into which the bus bar 3 is inserted, and a protruding piece 160 that is elastically deformable and has a claw portion 158 at the tip. I have. The bus bar insertion portion 156 and the projecting piece 160 extend along the axial direction of the housing through-hole 150 with the core housing portion 142 as a base point. The bus bar insertion portion 156 is formed with a bus bar pressing portion 162 that protrudes toward the bus bar insertion groove 154.

  As shown in FIGS. 5 to 8, the bus bar 3 as a conductive member is made of a conductive metal such as a copper alloy, and includes a plate-like central plate portion 30 in the middle portion in the longitudinal direction. The central plate portion 30 is formed with a long hole-shaped engagement notch portion 32 with which the claw portion 158 of the housing 14 is engaged. Further, on the side of the engagement notch 32 in the central plate portion 30, it protrudes in a direction perpendicular to the longitudinal direction of the bus bar 3 and the thickness direction of the bus bar 3 and is inserted into the bus bar insertion groove 154 of the housing 14. A protruding plate portion 34 is formed.

  On one end side of the bus bar 3, a substantially cylindrical bus bar cylinder portion 36 that is fitted to the terminal 20 of the battery 2 is formed. More specifically, the bus bar cylinder portion 36 is not continuous in the circumferential direction, and has an arc shape when viewed in the axial direction. Further, at both ends in the circumferential direction of the bus bar cylinder portion 36, plate-like bolt attachment plate portions 38 extending toward the radially outer side of the bus bar cylinder portion 36 are formed. The bolt mounting plate portion 38 is formed with a bolt insertion hole 40 into which a bolt is inserted.

  A harness (not shown) connected to the vehicle electrical components is coupled to the other end side of the bus bar 3 by caulking.

  In order to use the current sensor 1 configured as described above, first, the bus bar 3 to which the harness is coupled is inserted into the housing through-hole 150 from the bus bar cylinder part 36 side. Subsequently, the protruding plate portion 34 is inserted into the bus bar insertion groove portion 154 and the claw portion 158 of the projection piece 160 is engaged with the engagement notch portion 32 to perform relative positioning of the current sensor 1 and the bus bar 3. (See FIG. 6). Here, the protruding plate portion 34 is sandwiched between the bus bar pressing portion 162 and the plate surface facing the bus bar pressing portion 162 in the bus bar insertion portion 156, thereby preventing rattling. I am doing so.

  Subsequently, the bus bar cylinder portion 36 is fitted to the terminal 20 of the battery 2 (see FIG. 5), a bolt (not shown) is inserted into the bolt insertion hole 40, and the inserted bolt and nut (not shown) Are screwed together so that the bus bar cylinder portion 36 is crimped to the terminal 20.

  Subsequently, a connector (not shown) of an external device that inputs a detection signal of the current sensor 1 is inserted into the connector mounting portion 148, and the external device and a connector terminal in the connector mounting portion 148 are connected.

  When a current flows through the bus bar 3, a magnetic flux is generated in the core 10 by the current, and the Hall element 120 disposed in the magnetic path formed in the core gap 104 by the magnetic flux has a Hall effect corresponding to the magnetic flux. Generates a voltage (Hall voltage).

  Here, the Hall voltage generated by the Hall element 120 not only corresponds to the magnetic flux in the core 10, but also corresponds to the current value flowing through the bus bar 3 that generated the magnetic flux. I can say that. Therefore, the Hall voltage generated by the Hall element 120 is output as a detection signal to an external device.

  In this embodiment, since the projecting portion 106 is provided to reduce the cross-sectional area of the core gap 104, the permeance coefficient is reduced and the hysteresis is reduced. Accordingly, when the core through hole 108 is enlarged, the increase in hysteresis due to the increase in the magnetic path length of the core 10 is offset, and even if the core through hole 108 is enlarged, the increase in hysteresis is suppressed. And deterioration of current detection accuracy can be avoided.

  Further, by enlarging the core through-hole 108 and the housing through-hole 150, the bus bar 3 can be inserted into the housing through-hole 150 from the bus bar tube portion 36 side, and the bus bar 3 and the harness can be separated. There is no need to make it. Therefore, it is not necessary to employ a complicated configuration in which a terminal is caulked and coupled to a harness as in the prior art, and the terminal and the bus bar are fastened with screws.

  Further, since the core 10 is formed by bending the plate material, the waste material can be reduced as compared with the conventional method in which the plate material is sheared to form the core fragment.

(Second Embodiment)
A second embodiment of the present invention will be described. In the present embodiment, the configuration of the core 10 is different from that of the first embodiment, and the other parts are the same as those of the first embodiment. Therefore, only different portions will be described.

  As shown in FIG. 9, a plurality of types of cores 10 a, 10 b, and 10 c having different core plate widths that are dimensions in the axial direction of the core through-hole 108 (hereinafter referred to as the through-hole axial direction) are prepared. Specifically, a core 10a having a core plate width set to H, a core 10b having a core plate width set to 2 / 3H, and a core 10c having a core plate width set to 1 / 3H are prepared.

  Each of the cores 10a, 10b, and 10c has a dimension in the through-hole axial direction from one end surface (surface below the paper surface in FIG. 9) that contacts the bottom surface of the core housing portion 142 (see FIG. 1) to the protrusion 106. Are equal.

  Then, three types of cores 10a, 10b, and 10c are selectively used according to the required measurement range. Specifically, when the measurement range is wide, the core 10a having the largest core plate width is used, and the cores 10b and 10c having the smaller core plate width are used as the measurement range becomes narrower.

  By the way, when the protruding portion 106 is not formed, that is, when the facing piece 102 is a flat plate, the magnetic flux density of the core gap portion is the highest at the center portion of the core gap 104 in the through-hole axial direction. It is most desirable to place 120.

  Therefore, in the cores 10 having the opposed pieces 102 that are flat and different core plate widths, the optimum positions of the Hall elements 120 are different for the respective cores. For this reason, if the design is made such that the Hall element 120 is arranged at an optimal position with respect to the core 10c having the smallest core plate width, the Hall element is used when the cores 10a and 10b having the smallest core plate width are used. 120 does not become an optimal position, and becomes inefficient as a magnetic circuit.

  On the other hand, when the protrusion 106 is provided on the facing piece 102 as in this embodiment, the magnetic flux density is highest between the protrusions 106 even when the core plate width is different as shown in FIG. The interval is the optimum position of the Hall element 120.

  And since the dimension from the one end surface of each core 10a, 10b, 10c to the protrusion part 106 is equal, even if it uses any core 10a, 10b, 10c, while using components other than the core 10 as a common design, Hall element 120 may be disposed between the protrusions 106.

  According to this embodiment, the same effect as that of the first embodiment can be obtained.

  In addition, since the cores 10a, 10b, and 10c having different core plate widths are selectively used and the dimensions from one end surface of each of the cores 10a, 10b, and 10c to the protrusions 106 are made equal, parts other than the core 10 are commonly designed. Thus, it is possible to provide a current sensor that supports expansion and reduction of the measurement range.

(Third embodiment)
A third embodiment of the present invention will be described. In the present embodiment, the configuration of the core 10 is different from that of the second embodiment, and the other parts are the same as those of the second embodiment. Therefore, only different portions will be described.

  As shown in FIGS. 11 to 13, the first to third Hall elements 120 a, 120 b, and 120 c are arranged between the facing pieces 102 along the direction orthogonal to the through-hole axial direction. Moreover, the through-hole axial direction from the one end surface (surface below the paper surface of FIG. 12) which contact | abuts to the bottom face of the core accommodating part 142 (refer FIG. 1) in the core 10 to the 1st-3rd Hall elements 120a, 120b, 120c. The dimensions of are set equal.

  The first hall element 120a is disposed on the side farther from the core through hole 108 than the second hall element 120b and the third hall element 120c. The pair of facing pieces 102 are respectively formed with first protrusions 106a at positions facing each other across the first Hall element 120a.

  The second Hall element 120b is disposed closer to the core through hole 108 than the first Hall element 120a. Then, one of the pair of opposed pieces 102 is formed with a second protrusion 106b at a position facing the second Hall element 120b, and the other opposed piece is opposed to the second Hall element 120b. The protrusion 106 is not formed at the position.

  Further, the dimension in the axial direction of the through hole from one end surface of the core 10 that contacts the bottom surface of the core housing portion 142 to the first projection portion 106a, and the second projection from one end surface of the core 10 that contacts the bottom surface of the core housing portion 142. The dimension in the through-hole axial direction to the portion 106b is set equal.

  The third Hall element 120c is disposed closer to the core through hole 108 than the second Hall element 120b. And the protrusion part is not formed in the position which opposes the 3rd Hall element 120c in a pair of opposing piece 102. FIG.

  In the current sensor configured as described above, as shown in FIG. 14, the maximum value of the magnetic flux density in the core gap portion is maximum at the portion where the first Hall element 120a is disposed, and the portion where the third Hall element 120c is disposed. Is minimized. That is, the first Hall element 120a has the highest sensitivity, and the third Hall element 120c has the lowest sensitivity. Therefore, a plurality of outputs having different measurement ranges and current detection accuracy can be obtained.

  It is also possible to change the measurement range by changing the protruding amount of each of the protrusions 106a and 106b to control the magnetic characteristics. In addition, according to the half-cutting process, it is possible to freely and easily change the protruding amount of each protrusion 106a, 106b.

  By the way, if each Hall element 120a, 120b, 120c is located at the complete center of the core gap 104, it is not affected by the disturbance magnetic field, but cannot be set to 0 because of variation in assembly in manufacturing. When the core gap 104 is large, special design considerations are necessary so that the positional deviations of the Hall elements 120a, 120b, and 120c do not increase.

  And in the current sensor of this embodiment, it will be most affected with respect to the penetration | invasion of the disturbance magnetic field from A direction of FIG. 11, and it will become easy to receive the influence, so that the core gap 104 is wide.

  Here, as in the present embodiment, among the portions where the first to third Hall elements 120a, 120b, and 120c are disposed, the portion where the first Hall element 120a is disposed, that is, the first protrusion 106a is opposed. By disposing the portion where the core gap is substantially narrowest on the side far from the core through hole 108, the disturbance magnetic field is guided to the first protrusion 106a side, and the second Hall element 120b and the third Hall element The influence of the disturbance magnetic field on 120c can be reduced.

  According to this embodiment, the same effect as that of the first embodiment can be obtained.

  In addition, by arranging the first to third Hall elements 120a, 120b, and 120c at portions where the maximum magnetic flux density of the core gap portion is different, a plurality of outputs having different measurement ranges and current detection accuracy can be obtained.

  Furthermore, by disposing the part where the core gap is substantially narrowest on the side far from the core through hole 108, the influence of the disturbance magnetic field on the second Hall element 120b and the third Hall element 120c can be reduced. .

(Other embodiments)
Each of the above embodiments can be arbitrarily combined within a practicable range.

3 Busbar (conductive member)
DESCRIPTION OF SYMBOLS 10 Core 100 Core main-body part 102 Opposing piece 106 Protrusion part 120 Hall element 108 Through-hole 106a Protrusion part 120a Hall element

Claims (7)

A current sensor that includes a core (10) and a Hall element (120, 120a) and detects a current flowing through the conductive member (3),
The core is formed in a core body part (100) in which a plate material is formed into an annular shape by bending and a through hole (108) through which the conductive member is passed, and at both ends of the core body part. A pair of opposed pieces (102) arranged opposite to each other, and a pair of protrusions (106, 106a) formed on the opposed pieces and arranged opposite to each other,
The current sensor, wherein the Hall element is disposed between the protrusions.   The current sensor according to claim 1, wherein the protrusion is formed by half-punching. The surface facing the Hall element in the protrusion is a flat surface,
The area of the surface facing the Hall element in the protrusion is larger than the area of the surface facing the protrusion in the sensor chip (1200) of the Hall element. The current sensor described.   4. The current according to claim 1, wherein the core is selected from a plurality of types of cores (10 a, 10 b, 10 c) having different through-hole axial dimensions in the core. Sensor.   5. The current sensor according to claim 1, further comprising a hall element (120 b, 120 c) disposed between the pair of opposed pieces and not facing the pair of protrusions. 6. .   The Hall element disposed between the pair of protrusions is disposed on a side farther from the through hole than the Hall element disposed at a position not facing the pair of protrusions. The current sensor according to claim 5.   The current sensor according to claim 1, wherein the conductive member is a bus bar connected to a vehicle electrical component.

Images