JP2014098634A - Current sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a current sensor that is capable of reducing deterioration of measurement accuracy even if a magnetic shield member has a space.SOLUTION: A current sensor comprises: a current path (12) in which a first current path (12a) allowing measured current to flow in one direction and a second current path (12b) electrically connected to the first current path (12a) and allowing the measured current to flow in a direction opposite to the one direction are provided in parallel; multiple magnetoelectric transducers (13) that are provided corresponding to the first current path (12a) and the second current path (12b) and detect a magnetic field generated when the measured current flows through the current path (12); and a magnetic shield member (15) that covers the magnetoelectric transducer (13), the first current path (12a) and the second current path (12b). The magnetic shield member (15) has a space (15g) along the one direction, and the gap (15g) is provided at a position equally distant from both the first current path (12a) and the second current path (12b).

Description

  The present invention relates to a current sensor that detects a magnetic field generated when a current to be measured flows and measures a current to be measured flowing in a current path.

  In recent years, in order to control and monitor various devices, current sensors that are attached to various devices and measure currents flowing through the various devices have been generally used. As this type of current sensor, a current sensor using a magnetoelectric conversion element such as a magnetoelectric conversion element or a Hall element that senses a magnetic field generated from a current to be measured flowing in a current path is well known. In order to improve the measurement accuracy of the current sensor, a current sensor including a magnetic shield member that reduces the influence of an external magnetic field is well known.

  As the above-described current sensor, Patent Document 1 (conventional example) discloses a current sensor 900 as shown in FIG. 14A and 14B are diagrams illustrating a conventional current sensor 900. FIG. 14A is a diagram illustrating an outline of the configuration of the current sensor 900. FIG. 14B illustrates a magnetic field generated in the magnetic core 905. It is the figure which showed direction by simulation. A current sensor 900 shown in FIG. 14 includes a current measurement wiring (current bar) 902 having a parallel arrangement portion in which a part of the same wiring is arranged in parallel so that currents to be measured flow in opposite directions. Magnetic detection means (magnetic sensor) 903 for detecting a magnetic field in a direction perpendicular to a plane formed by parallel wirings, and current measurement wiring based on the magnetic field detected by the magnetic detection means (magnetic sensor) 903 (Current bar) 902 is configured to include a current detection means (coil) 904 that detects a current flowing in the 902 and a magnetic core 905 that surrounds the parallel arrangement portion. The magnetic core 905 reinforces the magnetic field generated by the current flowing through the current measurement wiring (current bar) 902 and detects that the external magnetic field is detected by the magnetic detection means (magnetic sensor) 903. It also has the function of a magnetic shield that shields the external magnetic field so as to suppress it. Thus, it is possible to provide a highly reliable current sensor 900 that suppresses erroneous detection of external magnetic noise at low cost.

  When using such a magnetic shield member, it is preferable for the magnetic shield to have no joints or gaps as the magnetic shield member. To that end, however, the magnetic shield member is difficult to be deep drawn or molded. I had to make it. For this reason, as in the conventional magnetic core 905 shown in FIG. 14B, it has been common to combine two components into a configuration having gaps (905a, 905b). In particular, in the case of a magnetic shield member having a function of only a magnetic shield, it was possible to produce a magnetic shield member easily and inexpensively by bending and processing a plate-like metal plate. Even in that case, it becomes the structure which has the clearance gap in either part.

JP 2010-276422 A

  However, although not shown in FIG. 14A, when there are gaps 905a and 905b as shown in FIG. Will be disturbed. For this reason, the magnetic field detected by the magnetic detection means (magnetic sensor) 903 becomes unstable, and there is a problem that the measurement accuracy of the current sensor 900 deteriorates.

  The present invention solves the above-described problems, and an object of the present invention is to provide a current sensor that can reduce deterioration in measurement accuracy even when there is a gap in a magnetic shield member.

  In order to solve this problem, the current sensor of the present invention includes a first current path through which a current to be measured flows in one direction, an electrical connection with the first current path, and a direction opposite to the one direction. A second current path through which the current to be measured flows in a direction, a current path disposed in parallel, and a first current path and a second current path, the current path being disposed in correspondence with the first current path and the second current path. A plurality of magnetoelectric transducers that detect a magnetic field generated when a measurement current flows; and a magnetic shield member that surrounds the magnetoelectric transducers, the first current path, and the second current path, and the magnetic shield member Has a gap along the one direction, and the gap is provided at a position equidistant from each of the first current path and the second current path.

  According to this, in the current sensor of the present invention, the gap between the magnetic shield members surrounding the first current path and the second current path is provided at a position equidistant from each of the first current path and the second current path. Therefore, the magnetic field in the gap is a magnetic field in which the magnetic field generated from the first current path and the magnetic field generated from the second current path are in opposite directions and have the same strength. For this reason, the leakage magnetic field which leaks from the clearance gap between the magnetic shield members can be reduced compared to the case where there is a gap on either side. Thereby, even if there is a gap in the magnetic shield member, the influence of the leakage magnetic field leaking from the gap is small, and the deterioration of the measurement accuracy can be reduced.

  In addition, the current sensor of the present invention includes a first magnetoelectric conversion element disposed corresponding to the first current path and a second corresponding to the second current path among the magnetoelectric conversion elements. There are at least one combination with the magnetoelectric conversion element, and the first magnetoelectric conversion element and the second magnetoelectric conversion element of the combination are provided at positions equidistant from the gap.

  According to this, since the first magnetoelectric conversion element arranged in the first current path and the second magnetoelectric conversion element arranged in the second current path are provided at positions equidistant from the gap, the external magnetic field The influence of the leakage magnetic field leaking from this gap due to the magnetic field generated when the current to be measured flows through the current path appears in the two magnetoelectric transducers with the same strength. For this reason, it is possible to more accurately cancel the influence of the leakage magnetic field by differentially processing the outputs from the two magnetoelectric conversion elements. Thereby, even if there is a gap in the magnetic shield member, the influence of the leakage magnetic field leaking from the gap is small, and the deterioration of the measurement accuracy can be further reduced.

  In the current sensor of the present invention, the magnetic shield member is formed by bending a single shield base material, and the gap is at one place.

  According to this, since the gap formed by bending one shield base material is one place, the leakage magnetic field from the gap is made smaller than in the case where the gap is two places or more. It is possible to further reduce the deterioration of measurement accuracy.

  In the current sensor of the present invention, the gaps of the magnetic shield members surrounding the first current path and the second current path are provided at equal distances from the first current path and the second current path. In the magnetic field of the part, the magnetic field generated from the first current path is opposite to the magnetic field generated from the second current path and has the same strength. For this reason, each magnetic field is canceled and the leakage magnetic field which leaks from the clearance gap between magnetic shield members can be suppressed small. Thereby, even if there is a gap in the magnetic shield member, the influence of the leakage magnetic field leaking from the gap is small, and the deterioration of the measurement accuracy can be reduced.

It is an exploded perspective view explaining the current sensor of a 1st embodiment of the present invention. It is a perspective view explaining the current sensor of a 1st embodiment of the present invention. It is a figure explaining the current sensor of 1st Embodiment of this invention, Comprising: It is the top view seen from the Z1 side shown in FIG. It is a figure explaining the current sensor of 1st Embodiment of this invention, Comprising: It is the top view which abbreviate | omitted a part of FIG. It is a figure explaining the current sensor of 1st Embodiment of this invention, Comprising: It is the top view which abbreviate | omitted a part of FIG. It is a figure explaining the current sensor of 1st Embodiment of this invention, Comprising: It is sectional drawing in the VI-VI line shown in FIG. It is a figure explaining the current sensor of 1st Embodiment of this invention, Comprising: It is sectional drawing in the VII-VII line shown in FIG. It is a block diagram explaining the current sensor of 1st Embodiment of this invention, Comprising: It is sectional drawing which showed an example of the relationship between the magnetic shielding member in FIG. 6, and an internal magnetic field. It is a block diagram explaining the current sensor of 1st Embodiment of this invention, Comprising: It is sectional drawing which showed an example of the relationship between the magnetic shielding member in FIG. 6, and an external part magnetic field. 10A is a model diagram simulating the influence of the gap of the magnetic shield member, FIG. 10A is a model diagram of the current sensor according to the first embodiment of the present invention, and FIG. 10B is a model diagram of Comparative Example 1, 10C is a model diagram of Comparative Example 2. FIG. 11A and 11B are simulation results of the current sensor according to the first embodiment of the present invention. FIG. 11A is a graph in which the influence of the internal magnetic field is compared between the models. FIG. 11B is an enlarged view of the P portion shown in FIG. It is a graph. It is the simulation result of the current sensor of 1st Embodiment of this invention, and is the graph which compared the influence by an external magnetic field between each model. FIG. 13A is a cross-sectional view of Modification 1 compared with FIG. 6, and FIG. 13B is a diagram of Modification 2 of the current path, illustrating a modification of the current sensor according to the first embodiment of the present invention. It is a perspective view. FIG. 14A is a diagram for explaining a conventional current sensor, and FIG. 14A is a diagram showing an outline of the configuration of the current sensor, and FIG. FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[First Embodiment]
FIG. 1 is an exploded perspective view illustrating a current sensor 101 according to the first embodiment of the present invention. FIG. 2 is a perspective view illustrating the current sensor 101 according to the first embodiment of the present invention. FIG. 3 is a diagram illustrating the current sensor 101 according to the first embodiment of the present invention, and is a top view seen from the Z1 side shown in FIG. 4 is a diagram illustrating the current sensor 101 according to the first embodiment of the present invention, and is a top view in which the upper case 11A of FIG. 3 is omitted. FIG. 5 is a diagram illustrating the current sensor 101 according to the first embodiment of the present invention, and is a top view in which a part of the magnetic shield member 15 of FIG. 4 is omitted. 6 is a diagram for explaining the current sensor 101 according to the first embodiment of the present invention, and is a cross-sectional view taken along the line VI-VI shown in FIG. FIG. 7 is a diagram illustrating the current sensor 101 according to the first embodiment of the present invention, and is a cross-sectional view taken along line VII-VII shown in FIG.

  As shown in FIGS. 1 to 5, the current sensor 101 according to the first embodiment of the present invention includes a current path 12 in which a first current path 12 a and a second current path 12 b are arranged in parallel, and a current path 12. And a plurality of magnetoelectric transducers 13 for detecting a magnetic field generated when a current flows through the magnetic field, and a magnetic shield member 15 surrounding the magnetoelectric transducers 13, the first current path 12a and the second current path 12b. The In addition, the current sensor 101 includes an insulating substrate 19 having a circuit pattern (not shown) that connects the plurality of magnetoelectric transducers 13, a support member 52 that positions and supports the current path 12, and a current path. 12, a magnetoelectric conversion element 13, a magnetic shield member 15, an insulating substrate 19, and a housing 11 that accommodates a support member 52 are provided.

  As shown in FIGS. 1 to 3, 6, and 7, the housing 11 is formed in a U shape with an upper case 11 </ b> A formed in a box shape and a bottom surface and side surfaces extending from both ends of the bottom surface. The lower case 11D. The insulating substrate 19, on which the magnetic sensor package 14 is mounted, the current path 12, the magnetic shield member 15, and the support member 52 are accommodated so as to be sandwiched between the upper case 11A and the lower case 11D. Further, as shown in FIGS. 2 and 3, a part of the current path 12 and a part of the support member 52 are protruded from the housing 11 and accommodated. In addition, synthetic resin materials such as ABS (acrylonitrile butadiene styrene), PET (polyethylene terephthalate), PBT (polybutylene terephthalate), and LCP (liquid crystal polymer) are used, which are produced by injection molding or the like.

  The current path 12 is made of a material having good conductivity such as copper (Cu) and has a U-shape in part as shown in FIGS. 1, 4 and 5. The first current path 12a and the second current path 12b are arranged in parallel, and a connecting portion 12k that electrically connects the first current path 12a and the second current path 12b. When the current to be measured flows through the current path 12, the current to be measured flows through the first current path 12a in one direction (for example, the Y1 direction shown in FIG. 5), and the second current path 12b passes through the connecting portion 12k. The current to be measured flows in the other direction opposite to the one direction (for example, the Y2 direction shown in FIG. 5).

  Further, the current path 12 is provided with a terminal portion 17a and a terminal portion 17b on the side opposite to the connecting portion 12k, in succession to the first current path 12a and the second current path 12b. (Y2 direction shown in FIG. 1). The end portions of the terminal portion 17a and the terminal portion 17b are provided with holes 17h for connecting and fixing a current path to be measured (current path to be measured) (not shown). Although connection and fixation of the current path 12 to the current path to be measured are not shown, they can be easily achieved by using the holes 17h of the current path 12 and using bolts, nuts, and the like. In addition, although copper (Cu) was used for the material of the electric current path 12, it is not limited to this, What is necessary is just a material with good electroconductivity, for example, aluminum (Al) etc. may be sufficient.

  In addition, when the current sensor 101 is assembled, the current path 12 is disposed on the upper side (Z1 side shown in FIG. 6) of the support member 52 shown in FIGS. Placed.

  The support member 52 uses a synthetic resin material such as ABS (acrylonitrile butadiene styrene), PET (polyethylene terephthalate), PBT (polybutylene terephthalate), LCP (liquid crystal polymer), and has a hole in the center as shown in FIG. Are formed of a flat base portion 52d provided with a plurality of portions extending from the base portion 52d. The plurality of portions are provided at a position sandwiched between the standing portion 52r formed on the left and right of one end portion (the Y2 direction side end portion shown in FIG. 1) of the base portion 52d. The projecting portion 52t and the extending portion 52e formed on the left and right of the other end portion (the Y1 direction end portion shown in FIG. 1) of the base portion 52d. Further, since the support member 52 uses a synthetic resin material, it is processed by injection molding or the like, and such a complicated shape can be easily produced.

  When the current path 12 is placed on the support member 52, as shown in FIGS. 1, 4 and 5, the inclined portions formed on the outer sides of the terminal portion 17a and the terminal portion 17b of the current path 12, respectively. 12m and an inclined wall 52k provided on the standing portion 52r of the support member 52 are brought into contact with each other. Further, the outer end face 12t of the U-shaped width direction (X direction shown in FIG. 5) of the current path 12 and the extending portion 52e of the supporting member 52 are brought into contact with each other, and the protruding portion of the supporting member 52 is provided. 52t is fitted into the slit portion 12s of the current path 12. As a result, the current path 12 and the support member 52 can be accurately positioned.

  The magnetoelectric conversion element 13 is an element that detects a magnetic field generated when a current flows through the current path 12. For example, a magnetic detection element (GMR (Giant Magneto Resistive) element) using a giant magnetoresistance effect is used. As shown in FIG. 1 and FIGS. 4 to 6, the first magnetoelectric transducer 13A disposed corresponding to the first current path 12a and the second corresponding to the second current path 12b are used. One set of two magnetoelectric conversion elements 13B is provided. The pair of magnetoelectric transducers 13 (the first magnetoelectric transducer 13A and the second magnetoelectric transducer 13B) were cut out after the GMR element was fabricated on the silicon substrate, and the GMR element was cut out to make a chip. The GMR element chip and a lead terminal 14r for signal extraction are electrically connected and packaged with a thermosetting synthetic resin to form a magnetic sensor package 14. Since this GMR element has a property that the resistance value of the GMR element changes according to the change of the magnetic field, the magnetoelectric conversion element 13 causes the current to be measured flowing in the current path 12 to flow from the change of the resistance value. By calculating, the measured current flowing in the current path 12 can be measured.

  The magnetoelectric conversion element 13 (the first magnetoelectric conversion element 13A and the second magnetoelectric conversion element 13B) is soldered to the lead terminal 14r and a circuit pattern (not shown), as shown in FIGS. As shown, the current path 12 is mounted on an insulating substrate 19 disposed to face the U shape. When the current path 12 and the insulating substrate 19 are disposed, as shown in FIGS. 4 to 6, the first magnetoelectric conversion element 13A is provided on the first current path 12a and the second The magnetoelectric conversion element 13B is provided on the other second current path 12b.

  Further, as shown in FIG. 5, the sensitivity axis direction KD of the first magnetoelectric conversion element 13A and the second magnetoelectric conversion element 13B is arranged in the same direction (X2 direction in FIG. 5), and The sensitivity influence axis direction ED of the first magnetoelectric conversion element 13A and the second magnetoelectric conversion element 13B is arranged so as to face the same direction (Y1 direction in FIG. 5). The current sensor 101 according to the first embodiment of the present invention calculates a signal from the first magnetoelectric conversion element 13A and a signal from the second magnetoelectric conversion element 13B, thereby measuring a current path to be measured (current path to be measured). ) Can be accurately measured. In the first embodiment of the present invention, the sensitivity influence axis direction ED is the direction of the bias applied to the magnetoelectric conversion element 13 (the first magnetoelectric conversion element 13A and the second magnetoelectric conversion element 13B). Although the case where the angle formed by the direction KD and the sensitivity affecting axis direction ED is 90 ° has been described, the angle is not limited to 90 °.

  The insulating substrate 19 uses a generally well-known single-sided printed wiring board, and a metal foil such as copper (Cu) provided on the base substrate is patterned on a glass-containing epoxy resin base substrate. A circuit pattern for configuring the circuit is formed. In addition, although the printed wiring board which consists of an epoxy resin containing glass was used for the insulating substrate 19, it is not limited to this, For example, a ceramic wiring board and a flexible wiring board may be used.

  When the insulating substrate 19 is disposed to face the current path 12, as shown in FIGS. 1, 4, 5, and 7, left and right outer peripheral side walls 19s on one end side of the insulating substrate 19 are provided. And the inner wall 52w of the extended portion 52e of the support member 52, the left and right outer peripheral walls 19t on the other end side of the insulating substrate 19, and the inner wall 52z of the standing portion 52r of the support member 52 Are in contact. As a result, the insulating substrate 19 and the support member 52 can be accurately positioned.

  The magnetic shield member 15 is made of silicon steel having a high magnetic permeability, and as shown in FIGS. 1, 6 and 7, is composed of an upper surface 15a, a bottom surface 15b, left and right side surfaces 15s, and a side surface 15t, and has a rectangular cylindrical shape. Molded. When the magnetic shield member 15 is assembled, as shown in FIGS. 4 to 6, the two magnetoelectric conversion elements 13 (the first magnetoelectric conversion element 13A and the second magnetoelectric conversion element 13B) and the first current path are provided. 12a and the second current path 12b are arranged so as to surround them. Although silicon steel is used as the material of the magnetic shield member 15, the material is not limited to this as long as the material has a magnetic shield effect.

  When the magnetic shield member 15 is assembled, as shown in FIGS. 4, 5, and 7, the left and right side surfaces 15 s of the magnetic shield member 15, the inner wall 15 w of the side surface 15 t, and the extending portion of the support member 52 are provided. The outer wall 52p of the magnetic shield member 15 is in contact with the left and right side surfaces 15s, the inner wall 15w of the side surface 15t, and the outer wall 52q of the standing portion 52r of the support member 52. Thereby, the magnetic shield member 15 and the support member 52 can be positioned accurately.

  The magnetic shield member 15 can be easily manufactured by bending one shield base material (silicon steel plate). Therefore, the magnetic shield member 15 is formed with one gap 15g along one direction (Y direction shown in FIGS. 1 and 4) on the upper surface 15a.

  As shown in FIGS. 6 and 7, the gap 15g is provided at a position equidistant from each of the first current path 12a and the second current path 12b. The relative positional relationship between the two can be accurately achieved by positioning the magnetic shield member 15 and the support member 52 and positioning the current path 12 and the support member 52.

  Further, as shown in FIGS. 4 and 6, the gap 15g is provided at a position equidistant from each of the first magnetoelectric conversion element 13A and the second magnetoelectric conversion element 13B. This can be accurately achieved by positioning the magnetic shield member 15 and the support member 52 and positioning the insulating substrate 19 on which the magnetoelectric conversion element 13 is mounted and the support member 52. . In the first embodiment of the present invention, the relative positions of the current path 12, the magnetoelectric transducer 13 and the magnetic shield member 15 are accurately determined with reference to the support member 52. However, the present invention is not limited to the support member 52. Alternatively, the case 11, the insulating substrate 19, or other parts may be used.

  Next, the shielding effect of the magnetic shield member 15 will be briefly described. FIG. 8 is a configuration diagram illustrating the current sensor 101 according to the first embodiment of the present invention, and is a cross-sectional view illustrating an example of the relationship between the magnetic shield member 15 and the internal magnetic field in FIG. 6. FIG. 9 is a configuration diagram illustrating the current sensor 101 according to the first embodiment of the present invention, and is a cross-sectional view illustrating an example of the relationship between the magnetic shield member 15 and the external magnetic field in FIG. 6.

  As shown in FIG. 8, the internal magnetic field generated by the first current path 12a through which the measured current flows in one direction and the internal magnetic field generated by the second current path 12b through which the measured current flows in the other direction opposite to the one direction. However, in the magnetic shield member 15, the directions of the magnetic shield members 15 cancel each other, so that the shielding effect of the magnetic shield member 15 is not saturated. Moreover, since the gap 15g of the magnetic shield member 15 is provided at a position equidistant from each of the first current path 12a and the second current path 12b, the magnetic fields in the gap 15g are in the opposite directions and the same. It is a strong magnetic field. For this reason, it is possible to suppress the leakage magnetic field leaking from the gap 15g of the magnetic shield member 15 smaller than when the gap 15g is biased to either side. As a result, even if there is a gap 15g in the magnetic shield member 15, the influence of the leakage magnetic field leaking from the gap 15g is small, and the deterioration of measurement accuracy can be reduced.

  Further, the magnetic shield member 15 is from the sensitivity axis direction KD that most affects the sensitivity of the magnetoelectric transducer 13 (13A, 13B) (in the X direction shown in FIG. 9, the direction of the arrow indicates a positive direction). Since this magnetic shield member 15 acts as a magnetic path for the incoming external magnetic field, the influence of the external magnetic field on the magnetoelectric transducer 13 can be reduced.

  Further, as shown in FIG. 9, for example, even if there is an external magnetic field MX from a direction perpendicular to the upper surface 15a with the gap 15g (Z1 direction shown in FIG. 9), it is disposed in the first current path 12a. Since the first magnetoelectric conversion element 13A and the second magnetoelectric conversion element 13B disposed in the second current path 12b are provided at the same distance from the gap 15g, the influence of the leakage magnetic field leaking from the gap 15g is affected. The two magnetoelectric transducers 13 appear with the same strength. For this reason, it is possible to more accurately cancel the influence of the leakage magnetic field by differentially processing the outputs from the two magnetoelectric conversion elements 13. Further, the influence of the leakage magnetic field leaking from the gap 15g due to the internal magnetic field generated when the current to be measured flows through the current path 12 can be accurately canceled out in the same manner. As a result, even if there is a gap 15g in the magnetic shield member 15, the influence of the leakage magnetic field leaking from the gap 15g is small, and the deterioration of measurement accuracy can be further reduced. In FIG. 9, the external magnetic field MX is symbolically shown as entering from the Z1 direction, but the same can be said for the external magnetic field entering from outside the Z1 direction.

  Furthermore, in the first embodiment of the present invention, since the gap 15g formed by bending one shield base material is one place, the gap 15g is larger than two places or more than the gap 15g. The leakage magnetic field from 15 g can be further reduced, and the deterioration of measurement accuracy can be further reduced.

  Finally, the results of verifying the effects described above will be described. FIG. 10 is a model diagram simulating the influence of the gap 15g of the magnetic shield member 15. FIG. 10A is a model diagram (AA) of the current sensor 101 according to the first embodiment of the present invention, and FIG. In the model diagram (BB) of Comparative Example 1, there is no gap of the magnetic shield member B15. FIG. 10C is the model diagram (CC) of Comparative Example 2, and the gap Cg of the magnetic shield member C15 is shifted to one side. Is the case. FIG. 11 is a simulation result of the current sensor 101 according to the first embodiment of the present invention. FIG. 11A is a graph in which the influence of the internal magnetic field is compared between the models. FIG. 11B is a P portion shown in FIG. It is the graph which expanded and showed. 11, A1 is the result of the model diagram (AA) of the current sensor 101, B1 is the result of the model diagram (BB) of Comparative Example 1, and C1 is the model diagram (CC) of Comparative Example 2. Is the result of FIG. 12 is a simulation result of the current sensor 101 according to the first embodiment of the present invention, and is a graph comparing the influence of an external magnetic field between models. The external magnetic field used in this simulation was a uniform magnetic field (1 mT) applied from the Z1 direction shown in FIG. Further, A2 in FIG. 12 is the result of the model diagram (AA) of the current sensor 101, B2 is the result of the model diagram (BB) of Comparative Example 1, and C2 is the model diagram of Comparative Example 2 ( CC). The horizontal axis of FIGS. 11 and 12 represents the center of the gap 15g shown in FIG. 10A as zero, the X1 direction as a positive position, and the X2 direction as a negative position, and the vertical axis represents magnetic flux density. .

  As a result, on the plus position side where the gap Cg of the magnetic shield member C15 is shifted to one side, as shown in FIG. 11B, the model diagram (AA) of the current sensor 101 and the model diagram of the comparative example 1 having no gap ( It can be seen that the result C1 of the model diagram (CC) of the comparative example 2 in which the gap Cg is shifted to one side is largely shifted, while the result B1 of BB) is substantially the same. This deviation of the gap Cg is one factor that causes a deterioration in measurement accuracy in Comparative Example 2. Thus, even if there is a gap 15g in the magnetic shield member 15, it can be said that the influence of the leakage magnetic field leaking from the gap 15g is small, and the deterioration of measurement accuracy can be reduced.

  In addition, as shown in FIG. 12, the result A2 of the model diagram (AA) of the current sensor 101 and the result B2 of the model diagram (BB) of the comparative example 1 without a gap tend to be the same, although there is a slight deviation. The result C2 of the model diagram (CC) of the comparative example 2 in which the gap Cg is shifted to one side is greatly shifted, and a significant shift occurs on the plus position side where the gap Cg of the magnetic shield member C15 is shifted to one side. I understand that. Due to this gap Cg deviation, compared to the current sensor 101 and the model of Comparative Example 1 without the gap, the deviation of the magnetic flux density is large and the balance between the left and right is worsened. Become. Thus, even if there is a gap 15g in the magnetic shield member 15, it can be said that the influence of the leakage magnetic field leaking from the gap 15g is small, and the deterioration of measurement accuracy can be reduced.

  As described above, in the current sensor 101 of the present invention, the gap 15g of the magnetic shield member 15 surrounding the first current path 12a and the second current path 12b is located at an equal distance from each of the first current path 12a and the second current path 12b. Therefore, the magnetic field in the gap 15g is a magnetic field having the same strength as the magnetic field generated from the first current path 12a and the magnetic field generated from the second current path 12b in opposite directions. For this reason, it is possible to suppress the leakage magnetic field leaking from the gap 15g of the magnetic shield member 15 smaller than when the gap 15g is biased to either side. As a result, even if there is a gap 15g in the magnetic shield member 15, the influence of the leakage magnetic field leaking from the gap 15g is small, and the deterioration of measurement accuracy can be reduced.

  In addition, since the first magnetoelectric conversion element 13A disposed in the first current path 12a and the second magnetoelectric conversion element 13B disposed in the second current path 12b are provided at equal distances from the gap 15g, The influence of the leakage magnetic field leaking from the gap 15g due to the external magnetic field or the magnetic field generated when the current to be measured flows through the current path 12 appears in the two magnetoelectric transducers 13 with the same strength. For this reason, it is possible to more accurately cancel the influence of the leakage magnetic field by differentially processing the outputs from the two magnetoelectric conversion elements 13. Thereby, even if there is a gap 15g in the magnetic shield member 15, the influence of the leakage magnetic field leaking from the gap 15g is small, and the deterioration of the measurement accuracy can be further reduced.

  In addition, since the gap 15g formed by bending one shield base material is one place, the leakage magnetic field from the gap 15g should be reduced as compared with the case where the gap 15g is two places or more. And the deterioration of measurement accuracy can be further reduced.

  In addition, this invention is not limited to the said embodiment, For example, it can deform | transform and implement as follows, These embodiments also belong to the technical scope of this invention.

  FIG. 13 is a diagram illustrating a modification of the current sensor 101 according to the first embodiment of the present invention. FIG. 13A is a cross-sectional view of Modification 1 compared with FIG. 6, and FIG. 13B is a current path. It is a perspective view of the modification 2 of 12.

<Modification 1>
In the first embodiment, the magnetic shield member 15 formed with one gap 15g is preferably used. However, as shown in FIG. 13A, the gap 15j extends from each of the first current path 12a and the second current path 12b. A configuration in which the gap 15j is provided at an equidistant position, and the gap 15j is provided at an equidistant position from the first and second magnetoelectric conversion elements 13A and 13B, and has two gaps (15g, 15j). But it ’s okay.

<Modification 2>
In the first embodiment, the current path 12 is formed in a U shape. However, if the first current path 12a and the second current path 12b arranged in parallel are electrically connected to each other. For example, as shown in FIG. 13B, the connecting portion 12j bent downward may be used, and the connecting portion may have any shape.

<Modification 3>
In the first embodiment, a configuration in which one set of the magnetoelectric conversion elements 13 is provided, but a configuration in which two sets of the magnetoelectric conversion elements 13 are provided, or a configuration in which more than one set is provided may be employed.

<Modification 4>
In the first embodiment, one shield base material (silicon steel plate) is bent and the magnetic shield member 15 is preferably used. However, a flat plate is formed on a synthetic resin such as ABS (acrylonitrile butadiene styrene) or PP (polypropylene). A magnetic shield member may be formed by combining two molded members formed by injection molding or the like by dispersing magnetic powder. In addition, a magnetic shield layer is applied to a synthetic resin member that does not contain magnetic powder and applied to either the entire inner surface or the entire outer surface of the synthetic resin member, and the two synthetic resin members are combined to form a magnetic shield member. Also good.

<Modification 5>
In the first embodiment, the current path 12 has a rectangular plate shape, that is, a so-called bus bar type. However, a current path of a circular or elliptical cross section may be used.

<Modification 6>
In the first embodiment, the magnetoelectric conversion element 13 is disposed with the insulating substrate 19 sandwiched between the current path 12, but the magnetoelectric conversion element 13 may be disposed facing the current path 12. .

<Modification 7>
In the first embodiment, the magnetoelectric conversion element 13 is packaged with a thermosetting synthetic resin to form the magnetic sensor package 14 and mounted on the insulating substrate 19. However, the magnetoelectric conversion element 13 is mounted on the insulating substrate 19 as it is, so-called Bare chip mounting may be used.

<Modification 8>
In the first embodiment, a GMR element is preferably used as the magnetoelectric conversion element 13, but in addition, an MR (Magneto Resistive) element, an AMR (Anisotropic Magneto Resistive) element, a TMR (Tunnel Magneto Resistive) element, a Hall element, and the like. It may be.

  The present invention is not limited to the above-described embodiment, and can be modified as appropriate without departing from the scope of the object of the present invention.

12 current path 12a first current path 12b second current path 13 magnetoelectric conversion element 13A first magnetoelectric conversion element 13B second magnetoelectric conversion element 15 magnetic shield member 15g, 15j gap 101 current sensor

Claims (3)

A first current path through which the current to be measured flows in one direction, and a second current path electrically connected to the first current path and through which the current to be measured flows in another direction opposite to the one direction, Current paths arranged in parallel;
A plurality of magnetoelectric transducers disposed corresponding to the first current path and the second current path and detecting a magnetic field generated when the current to be measured flows through the current path;
A magnetic shield member surrounding the magnetoelectric conversion element, the first current path, and the second current path;
The magnetic shield member has a gap along the one direction,
The gap is provided at a position equidistant from each of the first current path and the second current path. Of the magnetoelectric conversion elements, a combination of a first magnetoelectric conversion element arranged corresponding to the first current path and a second magnetoelectric conversion element arranged corresponding to the second current path is at least There are more than one set,
2. The current sensor according to claim 1, wherein the first magnetoelectric conversion element and the second magnetoelectric conversion element of the combination are provided at a position equidistant from the gap. The magnetic shield member is formed by bending one shield base material,
The current sensor according to claim 1, wherein the gap is one place.