Electric current sensor

Abstract

An electric current sensor 1 according to the present invention achieves a reduction in measurement accuracy degradation due to misalignment, and thus offers high measurement accuracy. The electric current sensor 1 comprises a magnetic detection unit 2, a case 3, a cover 4, and a busbar 5. The bus bar 5 includes a plate-like part 52 having a facing surface 51 formed to face the magnetic detection unit 2. The case 3 and the cover 4 clamp and hold the plate-like part 52 therebetween. The case 3 has a first reference surface S1. The cover 4 has a second reference surface S2. The busbar 5 has a third reference surface S3. The case 3, the cover 4, and the busbar 5 are positioned through the first reference surface S1 and the second reference surface S2 being pressed against the third reference surface S3. The third reference surface S3 is an end surface 53 in the plate thickness direction of the plate-like part 52 of the busbar 5.

Description

Current Sensor

[0001] The present invention relates to a current sensor that measures a current to be measured that flows through a bus bar.

[0002] In recent years, current sensors have been used to measure the current flowing through devices to control the power supply systems of vehicles and other devices equipped with various devices. Examples include coreless current sensors in which the bus bar is insert-molded into the case, and current sensors that use bus bars that are not insert-molded into the case in order to meet market demands for lower costs. Current sensors that do not insert-molde the bus bar into the case but instead integrate the case and bus bar through assembly make it possible to accommodate bus bars of various shapes.

[0003] Patent document 1 discloses an assembly structure for a current detection device in which a convex portion formed on a cover passes through a hole formed in a bus bar and engages with a hole formed on the underside of a housing, with the aim of providing an assembly structure for a current detection device that is simple in configuration, easy to assemble, and suitable for miniaturizing the current detection device.

[0004] Patent Document 2 discloses a current sensor that aims to provide a highly accurate current sensor, in which a magnetic sensor element is fixed to a holder by screwing the holder to a current bar.

[0005] Patent Document 3 discloses a current sensor that aims to provide a current sensor that can suppress misalignment between a bus bar and a magnetic detection element, and has first and second housings that are arranged to sandwich a bus bar and a circuit board, and the first and second housings abut each other in the thickness direction of the bus bar and have slide guide portions that are slidable relative to each other in a direction inclined with respect to the thickness direction of the bus bar. In this current sensor, the bus bar is positioned relative to the housing by fitting a protrusion of the first housing into a notch in the bus bar.

[0006] Patent Document 4 discloses a current sensor in which a magnetic-sensing element mounting portion, a magnetic-material mounting portion, and a bus bar are positioned and fixed in the thickness direction of the magnetic-material mounting portion, with the aim of providing a current sensor that has few restrictions on the bus bar shape and is capable of measuring current with high accuracy by reducing deterioration in accuracy due to relative positional misalignment between the magnetic material, the bus bar, and the magnetic-material sensing element. In this current sensor, the bus bar is positioned in the width direction based on the wall of the magnetic-material mounting portion.

[0007] JP 2010-243440 A JP 2015-31647 A JP 2019-105613 A JP 2021-152515 A

[0008] In the current detection devices and current sensors described in Patent Documents 1 and 2, the bus bar is attached to the case based on the screw fastening holes provided in the bus bar, not the sensing unit. This may result in a decrease in the accuracy of the current sensor due to variations in the characteristics of the bus bar attached to the case. In both of the current sensors described in Patent Documents 3 and 4, only one of the separable cases is positioned directly relative to the bus bar, while the other is positioned based on the first case. This may result in a decrease in the accuracy of the current sensor due to misalignment when positioning one case relative to the other. Therefore, an object of the present invention is to provide a current sensor with high measurement accuracy that suppresses a decrease in measurement accuracy due to misalignment.

[0009] In order to solve the above-described problems, the present invention provides a current sensor including a magnetic detection unit, a case, a cover, and a bus bar, wherein the bus bar extends in the X direction among mutually orthogonal X, Y, and Z directions and has a plate-like portion formed with an opposing surface facing the magnetic detection unit with the Z direction as its normal direction, and the case and the cover sandwich and hold the plate-like portion with the opposing surface of the bus bar from both sides in the Z direction, the current sensor being characterized in that the case has a first reference surface, the cover has a second reference surface, and the bus bar has a third reference surface, the first reference surface and the second reference surface are pressed against the third reference surface to position the case, the cover, and the bus bar, and the third reference surface is an end surface of the plate-like portion of the bus bar in the Y direction.

[0010] Both the case and the cover are positioned by pressing their first and second reference surfaces against the third reference surface of the bus bar, thereby minimizing misalignment due to variations in size and assembly. Furthermore, by using the Y-direction end face of the plate-like portion, which has a surface facing the magnetic detection unit, as the third reference surface for positioning, the positional relationship in the Y direction between the case, cover, and bus bar can be precisely determined near the sensing unit, which is the detection target of the magnetic detection unit. This allows for the provision of a current sensor with high measurement accuracy.

[0011] The bus bar may have a constricted portion with a notch recessed in the Y direction, and the third reference surface may be one of the end faces of the constricted portion in the Y direction. The case may have a bus bar groove in a surface facing the cover, the bus bar groove including a guide portion that protrudes in the Y direction when viewed along the Z direction, the guide portion being inserted into the notch, and the first reference surface may be located at a position facing the third reference surface.

[0012] The cover may have a support post protruding in the Z direction from a surface facing the case, the guide post and the support post being inserted into and fitted to the notch, and the support post having the second reference surface at a location facing the third reference surface. Two guide parts that form a pair in the X direction may be spaced apart with a gap between them, the support post fitting into the gap, and the two guide parts and the support post that form a pair in the X direction may fit into the notch. A structure in which the two guide parts and the support post located in the gap fit into the notch of the bus bar reduces wobble of the bus bar in the X direction when the bus bar is incorporated into the case.

[0013] The bus bar may have the notches on both sides of the plate-shaped portion in the Y direction, the case may have two guide portions that correspond to the two notches and form a pair in the X direction, and the cover may have two support members that correspond to the two notches, where the end face of the constricted portion of one of the notches is the third reference surface, the guide portion that fits into one of the notches has the first reference surface, and the support member that fits into the gap between the two guide portions that form a pair in the X direction and fit into one of the notches has the second reference surface. This configuration allows the case and cover to be positioned relative to the bus bar. Furthermore, by bringing the surfaces into contact with each other, rattle in the rotational direction along the X-Y plane can be suppressed.

[0014] The other end face opposite to the one end face having the third reference surface in the constricted portion may be a pressing surface, and the guide portions facing the pressing surface may each have a first convex portion protruding in the Y direction on the surface facing the pressing surface, and the support portion may have a second convex portion protruding in the Y direction on the surface facing the pressing surface, and the first convex portion and the second convex portion may be pressed against the pressing surface.

[0015] By providing the first and second protrusions that protrude in the Y direction, it is possible to press a pressing surface provided on the other end face of the constricted portion opposite the end face having the third reference surface, thereby ensuring reliable positioning by bringing the first reference surface of the guide portion and the second reference surface of the support portion into firm contact with the third reference surface on one end face of the constricted portion.

[0016] The notch portion may have X-facing surfaces facing each other in the X direction, and one of the two guide portions that form a pair in the X direction may have a third convex portion that protrudes in the X direction on a surface that faces one of the X-facing surfaces in one of the guide portions, and a surface that faces the other facing surface in the other of the guide portions may be in contact with the other facing surface in the notch portion, with the third convex portion being in pressure contact with one of the facing surfaces.

[0017] The third protrusion of one guide portion presses against one of the X-facing surfaces of the cutout portion, thereby bringing the surface of the other guide portion facing the X-facing surface into contact with the other X-facing surface of the cutout portion via the support portion of the cover. This allows the X-direction positions of the case and cover relative to the bus bar to be accurately determined based on the bus bar.

[0018] The magnetic shielding member may have a U-shaped magnetic shielding member, which is insert-molded into the cover, with both ends protruding from the surface of the cover facing the bus bar, and a pair of the support portions may be arranged between the ends of the magnetic shielding member and in contact with the magnetic shielding member, and when viewed from the case side to the cover side along the Z axis, the magnetic detection portion may be arranged between the ends of the magnetic shielding member.

[0019] The U-shaped magnetic shielding member reduces external magnetic noise, improving the measurement accuracy of the current sensor. Furthermore, by arranging each of the pair of support posts inside the magnetic shielding member, the external shape of the current sensor becomes compact. Furthermore, the deterioration of the linearity of the measurement by the current sensor due to the tilt (warping / deformation) of the magnetic shielding member is suppressed.

[0020] The case may have a shielding hole through which the end of the magnetic shielding member can be inserted without contacting the guide portion. By configuring the tip of the magnetic shielding member not to contact the guide portion, the magnetic shielding member does not interfere when positioning the case, cover, and bus bar, improving workability.

[0021] The dimension of the magnetic shield member in the Y direction may be smaller than the dimension of the bus bar in the Y direction, and the magnetic shield member may be disposed so as not to protrude from the bus bar in the Y direction. By making the dimension of the magnetic shield member smaller than the width of the bus bar, it is possible to provide a current sensor that is compact in the width direction, is less susceptible to the influence of external magnetic fields, and has excellent noise resistance.

[0022] The connector may include a pair of retaining members that hold the case, the cover, and the bus bar together, the bus bar having a pair of insertion holes through which the retaining members can be inserted, the pair of insertion holes being located on either side of a constricted portion in the X direction. The retaining members may be screws. With the above configuration, the case, the cover, and the bus bar can be held together by a pair of retaining members such as screws.

[0023] The magnetic detection unit may be mounted on a case-facing surface of the board that faces the case, the board being provided on a board-facing surface of the case opposite the busbar-facing surface that faces the busbar, the board having the cutout portion, and the case having an engaging portion that protrudes from the board-facing surface, and the board may be positioned relative to the case by engagement between the cutout portion and the engaging portion.

[0024] The cover may have a second insertion hole through which the screw can be inserted, and the case may have a screw hole boss protruding in the Z direction from the board-facing surface, the board being located between the two screw hole bosses in the X direction when viewed along the Z direction, and the board being located closer to the board-facing surface of the case than a straight line connecting the tips of the two screw hole bosses when viewed along the Y direction. The two screw hole bosses protect the board between them and ensure an insulating distance between the outside and the board, thereby enabling the current sensor to be made low-profile.

[0025] The case may have a wall portion that protrudes in the Z direction from the board-facing surface so as to surround the periphery of the board, and the wall portion may protrude from the board-facing surface to a position at least as far as the back surface of the case-facing surface of the board. By surrounding the periphery of the board with a wall portion that extends from the board-facing surface of the case to a position higher than the board, the board is protected and is less likely to receive a direct impact when it comes into contact with the outside, preventing damage to the board and improving the reliability of the current sensor.

[0026] The cover may have a protrusion on a bottom surface opposite to the busbar-facing surface that faces the busbar and a bottom portion that is a region other than the protrusion, a portion of a magnetic shielding member is insert-molded inside the protrusion, a second insertion hole through which the screw can be inserted is provided in the bottom portion of the bottom surface, and a height from the bottom to a tip of the protrusion in the Z direction is greater than a height from the bottom to a head of the screw inserted in the second insertion hole. By providing the protrusion, into which the portion of the magnetic shielding member is insert-molded, higher than the head of the screw, interference between the head of the screw and other members can be prevented.

[0027] The cover may include a partition wall portion that protrudes from the bottom portion in the Z direction and extends in the X direction. The partition wall portion may be disposed on both sides of the second insertion hole in the Y direction. By providing a partition wall portion in addition to a protruding portion, stability is improved when the current sensor is placed with the protruding portion facing down. Furthermore, contact between the head of the screw and other members can be prevented, thereby improving the insulation of the screw.

[0028] The height of the partition wall from the bottom in the Z direction may be the same as the height of the protruding portion of the bottom surface from the bottom. With the above configuration, there is no step between the partition wall and the protruding portion, and therefore the stability of the current sensor is improved when the cover is placed with the protruding portion facing downward.

[0029] The current sensor may include three fixing parts for fixing the substrate to the cover. The three fixing parts prevent the cover and the substrate from being misaligned relative to each other, thereby preventing deterioration of the measurement accuracy of the current sensor due to the misalignment between them.

[0030] When viewed from the Z direction, a right-angled triangle is formed by three straight lines connecting the fixed parts, and the opposite side and adjacent side that intersect at a right angle in the right-angled triangle are each parallel to the X direction or the Y direction, and the hypotenuse opposite the right angle corner of the right-angled triangle may overlap with a part of the magnetic detection unit.

[0031] One of the bus bar protruding portions protruding from both sides of the case may have a bent portion, and two of the three fixing portions may be provided in an area closer to the bent portion than the center of the board in the X direction. Because deformation is likely to occur in the portion of the case close to the bent portion when fastening the bus bar, the two fixing portions are provided in an area close to the protruding portion having the bent portion. This increases the force that secures the board to the case in the portion that is likely to deform. Therefore, even if the case deforms when fastening the bus bar, the board can remain fixed to the case.

[0032] A current sensor having a magnetic detection unit, a case, and a cover, and in which a bus bar is held by the case and the cover, characterized in that the case has a first reference surface that is pressed against an end face of the bus bar in the width direction to position it, and the cover has a second reference surface that is pressed against the end face of the bus bar in the width direction to position it.

[0033] The present invention uses the bus bar as a reference for positioning the case and cover, thereby preventing the detection accuracy of the current sensor from deteriorating due to misalignment. Therefore, it is possible to provide a current sensor with high measurement accuracy in which the decrease in measurement accuracy due to misalignment is suppressed.

[0034] 1 is a perspective view showing the appearance of a current sensor according to a first embodiment of the present invention. FIG. 2 is a perspective view showing a state in which a case and a substrate are removed from the current sensor of FIG. 1. FIG. 3 is a partial cross-sectional view taken along the XY plane near the surface of the bus bar of the current sensor at line A-A in FIG. 1. FIG. 4 is a partial cross-sectional view taken along the XY plane near the surface of the bus bar of the current sensor at line A-A in FIG. 1. FIG. 5 is a perspective view showing a cover and a magnetic shield member of the current sensor. FIG. 6 is a perspective view showing a case of the current sensor. FIG. 7 is a plan view showing the positional relationship between the bus bar and the magnetic shield member of the current sensor. FIG. 8 is a cross-sectional view taken along the XZ plane of the current sensor at line B-B in FIG. 1. FIG. 9 is a perspective view showing the appearance of the current sensor as seen from the case side. FIG. 10 is a perspective view showing the appearance of the current sensor as seen from the cover side. FIG. 11 is a perspective view showing the appearance of a modified current sensor. FIG. 12 is a partial cross-sectional view of another modified current sensor taken along the XY plane near the surface of the bus bar of the current sensor at a portion corresponding to A-A in FIG. 1.

[0035] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. The same components in each drawing are designated by the same numbers, and descriptions thereof will be omitted where appropriate. Reference coordinates are shown in each drawing as appropriate to indicate the positional relationship of each component. In the reference coordinates, the extension direction of the bus bar is defined as the X direction, the width direction of the bus bar perpendicular to the X direction is defined as the Y direction, and the stacking direction of the bus bar and magnetic detection unit perpendicular to the X and Y directions is defined as the Z direction. The Y direction is the direction of the sensitivity axis of the magnetic detection unit, and the X and Z directions are perpendicular to the sensitivity axis.

[0036] Fig. 1 is a perspective view showing the appearance of a current sensor 1 according to this embodiment. Fig. 2 is a perspective view showing the current sensor 1 with a case 3 and a substrate 9 removed. Fig. 3 is a partial cross-sectional view taken along line A-A in Fig. 1 and cut in the XY plane near the surface of a bus bar 5 of the current sensor 1. As shown in Figs. 1 to 3, the current sensor 1 has a magnetic detection unit 2, a case 3, a cover 4, and a bus bar 5.

[0037] The magnetic detection unit 2 detects the magnetic field generated by the busbar 5 when a current to be measured flows through the busbar 5. The magnetic detection unit 2 is mounted on the substrate 9 so as to face the busbar 5 in the Z direction, among the mutually orthogonal X, Y, and Z directions. The sensitivity axis of the magnetic detection unit 2 is the Y direction, and the magnetic detection unit 2 can detect magnetic fields in the Y direction. Note that, because a current flows through the busbar 5 along the X direction, by facing the detection surface of the magnetic detection unit 2 directly to the busbar 5, the magnetic field generated by the busbar 5 as an induced magnetic field can be accurately detected by the magnetic detection unit 2. A magnetoresistive effect element, a Hall element, or the like can be used as the detection element of the magnetic detection unit 2. Note that the above-described configuration illustrates an example in which a magnetoresistive effect element is used as the detection element, and the magnetic detection unit 2 is positioned with its detection surface facing the busbar 5. If another detection element is used, the orientation of the detection surface must be appropriately changed.

[0038] The bus bar 5 extends in the X direction, has a plate-shaped portion 52 with a facing surface 51 facing the magnetic detection unit 2, and has notches 54 formed in a concave shape on both sides of the plate-shaped portion 52 in the Y direction. The notches 54 are formed symmetrically with respect to the center line of the plate-shaped portion 52 in the Y direction. The bus bar 5 is a plate-shaped conductor through which the current to be measured flows, and is made of, for example, copper, brass, or aluminum. In the current sensor 1, the plate-shaped portion 52 with the facing surface 51 of the bus bar 5 is sandwiched and held between the case 3 and the cover 4 on both sides in the Z direction.

[0039] The case 3 and the cover 4 are made of resin or the like. The case 3 has a first reference surface S1, the cover 4 has a second reference surface S2, and the bus bar 5 has a third reference surface S3. The first reference surface S1 of the case 3 and the second reference surface S2 of the cover 4 are pressed against the third reference surface S3 of the bus bar 5, thereby positioning the case 3, the cover 4, and the bus bar 5 relative to each other.

[0040] 3, the first reference surface S1 and the second reference surface S2 of each of the case 3 and the cover 4 (see FIGS. 1 and 2) are pressed against the third reference surface S3 of the bus bar 5, and the third reference surface S3 is used to position the case 3 and the cover 4 in the Y direction relative to the bus bar 5. By positioning the case 3 and the cover 4 using the bus bar 5 as a reference in this way, it is possible to minimize misalignment in the Y direction that may occur due to variations in dimensions or assembly, etc.

[0041] As will be described in detail later, the substrate 9 on which the magnetic detection unit 2 is mounted is attached to the Z2-side surface (substrate-facing surface 34, see FIG. 6 ) of the case 3. As described above, by pressing the first reference surface S1 of the case 3 against the third reference surface S3 of the bus bar 5, the position of the case 3 in the Y direction relative to the bus bar 5 can be determined with high precision. Therefore, the positional deviation of the magnetic detection unit 2 in the Y direction relative to the bus bar 5 can be kept small.

[0042] Here, we will explain the magnetic field that is generated when a current to be measured flows through the bus bar 5. When the generated magnetic field is viewed along the X direction, an elliptical magnetic field with its major axis extending along the Y direction is formed around the bus bar 5. Therefore, the further away in the Y1 direction or Y2 direction from the center position of the bus bar 5 in the Y direction is, the smaller the Y direction component of the magnetic field that the magnetic detection unit 2 can detect becomes, and the larger the Z direction component becomes.

[0043] That is, if there is a positional deviation between the bus bar 5 and the magnetic detection unit 2 in the Y direction, this will affect the measurement accuracy of the magnetic detection unit 2. Therefore, by positioning the case 3 and the cover 4 based on the bus bar 5, it is possible to reduce variations in the measurement accuracy of the magnetic detection unit 2.

[0044] Furthermore, the current sensor 1 uses, as a third reference plane S3, an end face (plate thickness plane) 53 in the Y direction of the plate-shaped portion 52 of the busbar 5, which has a surface 51 facing the magnetic detection unit 2. That is, the end face 53 on the Y1 side of the notch 54 in the Y direction functions as the third reference plane S3 used as a reference for positioning. In this way, by using the plate-shaped portion 52 located near the magnetic detection unit 2 as a reference for positioning, the positional relationship in the Y direction between the case 3, the cover 4, and the busbar 5 can be precisely defined. Therefore, deterioration of the detection accuracy of the current sensor 1 due to deviation from the predetermined position can be suppressed.

[0045] 3 illustrates a case where the contact between the first reference surface S1 and the third reference surface S3 and the contact between the second reference surface S2 and the third reference surface S3 are both surface-to-surface contact. However, the positioning mode is not limited to surface contact. For example, at least one of the two contacts described above may be point contact or line contact. In this case, one or both of the two contacts may be a line, a point, or a surface.

[0046] 3 has narrow portions 55 with notches 54 recessed in the Y direction formed on both sides in the Y direction, and wide portions without the notches 54. By providing the narrow portions 55, which are narrower than the wide portions, between the wide portions on both sides in the X direction, the influence of the skin effect at high frequencies can be suppressed in the narrow portions 55. Therefore, measuring the magnetic field generated in the narrow portions 55 with the magnetic detection unit 2 results in a current sensor 1 with high measurement accuracy.

[0047] The case 3 has a busbar groove 31 in which the busbar 5 can be placed, on its surface on the Z1 side facing the cover 4. The busbar groove 31 has a guide portion 32 that protrudes in the Y direction when viewed along the Z direction. When the busbar 5 is placed in the busbar groove 31, the guide portion 32 is inserted into the cutout portion 54. The guide portion 32 has a first reference surface S1 at a location that faces the third reference surface S3 when inserted into the cutout portion 54.

[0048] In the case 3 shown in Figure 3, when viewed along the Z direction, the guide portions 32 protrude from both sides of the bus bar groove portion 31 in the Y direction toward the constricted portion 55 of the bus bar 5 so as to face each other in the Y direction.

[0049] The cover 4 has a support portion 41 that protrudes toward the Z2 side in the Z direction from a busbar facing surface 42 (see FIG. 2 ) that faces the case 3. The guide portion 32 of the case 3 and the support portion 41 of the cover 4 are inserted into the notch portion 54 of the busbar 5. That is, when viewed along the Z direction, the guide portion 32 and the support portion 41 are provided at positions that overlap the notch portion 54 of the busbar 5.

[0050] The support pillar 41 has a second reference surface S2 at a location facing the third reference surface S3 of the bus bar 5 when the support pillar 41 is inserted into the notch 54. Two guide portions 32 that are paired in the X direction are spaced apart and overlap one of the notches 54 when viewed along the Z direction. A gap 32D is formed between the two guide portions 32, allowing the support pillar 41 to fit into the gap 32D. When the case 3 and the cover 4 are engaged with each other, the support pillar 41 is inserted into and fits into the gap 32D. In other words, when the bus bar 5 is sandwiched between the case 3 and the cover 4, the two guide portions 32 that are paired in the X direction and the support pillar 41 that is fitted into the gap 32D are integrated and fit into the notch 54 of the bus bar 5. With this configuration, assembling the bus bar 5 into the case 3 and the cover 4 reduces wobble in the X-Y plane.

[0051] The bus bar 5 has notches 54 on both sides of the plate-like portion 52 in the Y direction. The case 3 has two guide portions 32 that correspond to the two notches 54 and form a pair in the X direction. The cover 4 has two support posts 41 that correspond to the two notches 54. In FIG. 3 , the end face 53 of the constricted portion 55 in one of the notches 54 on the Y1 side of the bus bar 5 is the third reference surface S3. The guide portion 32 that fits into one of the notches 54 has the first reference surface S1, and the support post 41 that fits into the gap 32D between the pair of two guide portions 32 that fit into one of the notches 54 has the second reference surface S2.

[0052] In this manner, the support pillars 41 are fitted into the gaps 32D of the guide pillars 32 with the first reference surfaces S1 of the pair of guide pillars 32 and the second reference surfaces S2 of the support pillars 41 in contact with the third reference surfaces S3 of the notches 54. The guide pillars 32 and the support pillars 41, which are integrated through fitting, are fitted into the notches 54, thereby enabling the positions of the case 3 and the cover 4 in the Y direction relative to the busbar 5 to be determined reliably and stably.

[0053] 4 is a partial cross-sectional view taken along line A-A in Fig. 1, cutting the vicinity of the surface of the busbar 5 of the current sensor 1 in the XY plane. As shown in the figure, the end face 53 of the constricted portion 55 opposite to the one end face 53 having the third reference plane S3 is the pressing surface SP. The guide portions 32c and 32d facing the pressing surface SP each have a first protrusion 321 that protrudes toward the Y1 side in the Y direction on the surface facing the pressing surface SP.

[0054] The support portion 41b, which fits into the gap 32D between the two guide portions 32c and 32d having the first protrusion 321, has a second protrusion 412 that protrudes toward the Y1 side in the Y direction on the surface opposite the pressing surface SP.

[0055] The distance from the Y1-side ends of the first convex portion 321 and the second convex portion 412 to the guide portions 32a and 32b arranged opposite the Y1 sides of the first convex portion 321 and the second convex portion 412 is set to be the same as or slightly smaller than the dimension in the Y direction of the constricted portion 55 of the bus bar 5. Therefore, the first convex portion 321 and the second convex portion 412 press against the pressing surface SP, urging the bus bar 5 in the direction of the white arrow shown in Figure 4 (towards the Y1 side in the Y direction). In Figure 4, the white arrow indicates the direction in which the first convex portion 321 and the second convex portion 412 press against the pressing surface SP to urge the bus bar 5.

[0056] The first protrusion 321 and the second protrusion 412 press a pressing surface SP provided on the other end face 53 of the constricted portion 55 of the busbar 5 toward the Y1 side in the Y direction. This allows the first reference surfaces S1 of the guide portions 32c and 32d and the second reference surface S2 of the support portion 41b to reliably and stably contact the third reference surface S3 of one end face 53 on the Y1 side of the constricted portion 55. Therefore, the case 3 and the cover 4 can be directly positioned in the Y direction using the end face 53 of the constricted portion 55 of the busbar 5 as a reference.

[0057] The two cutouts 54 each have an X-facing surface 54S that faces each other in the X direction. The pair of guide portions 32a and 32b are inserted (placed) side by side in the X direction between the facing X-facing surfaces 54S, with a gap 32D between them. Similarly, the pair of guide portions 32c and 32d are inserted (placed) side by side in the X direction, with a gap 32D between them. The guide portions 32a and 32b form a pair in the X direction, and the guide portions 32c and 32d form a pair in the X direction.

[0058] Of the two paired guide portions 32a, 32b, one guide portion 32a has a third convex portion 323 that protrudes in the X direction formed on a surface facing one X-facing surface 54S of the notched portion 54, and the third convex portion 323 is in pressure contact with one X-facing surface 54S. The other guide portion 32b has a surface facing the other X-facing surface 54S of the notched portion 54 that is in contact with the other X-facing surface 54S. Similarly, of the two paired guide portions 32c, 32d, one guide portion 32c has a third convex portion 323 formed thereon, and the other guide portion 32d is in contact with the X-facing surface 54S.

[0059] Of the two paired guide portions 32a, 32b, the third convex portion 323 of one guide portion 32a is in pressure contact with one X-facing surface 54S of the cutout portion 54. This ensures that the surface of the other guide portion 32b facing X-facing surface 54S and the other X-facing surface 54S of the cutout portion 54 are in surface contact with each other via the support portion 41a of the cover 4.

[0060] Similarly, of the pair of guide portions 32c, 32d, the third convex portion 323 of one guide portion 32c is pressed against one X-facing surface 54S of the cutout portion 54. This ensures that the surface of the other guide portion 32d that faces X-facing surface 54S and the other X-facing surface 54S of the cutout portion 54 are in reliable contact with each other via the support portion 41b of the cover 4.

[0061] With the above configuration, the positions of the case 3 and the cover 4 in the X direction relative to the bus bar 5 can be determined based on the X-facing surface 54S of the bus bar 5. Therefore, the relative positions of the case 3 and the cover 4 and the bus bar 5 in the X direction can be determined with high accuracy.

[0062] 5 is a perspective view showing the cover 4 and the magnetic shield member 6 of the current sensor 1 (see FIG. 1). As shown in the figure, the current sensor 1 has a U-shaped magnetic shield member 6. At least a portion of the magnetic shield member 6 is insert-molded into the cover 4, and an end 6E protrudes from a bus bar facing surface 42 of the cover 4 that faces the bus bar 5. In addition, a pair of support portions 41 are each disposed between the ends 6E of the magnetic shield member 6 and in contact with the magnetic shield member 6. When viewed from the case 3 side to the cover 4 side along the Z axis, the magnetic detection unit 2 is disposed between the ends 6E of the magnetic shield member 6.

[0063] For example, a plurality of identically shaped metal plates stacked on top of each other can be used as the magnetic shield member 6. The magnetic shield member 6 can suppress magnetic noise in the magnetic detection unit 2, thereby improving the measurement accuracy of the current sensor 1.

[0064] By disposing the pair of support posts 41 inside the magnetic shield member 6, i.e., between the ends 6E of the magnetic shield member 6, the external shape of the current sensor 1 can be made compact. In addition, deterioration of the linearity of the output of the current sensor 1 due to tilting (warping / deformation) of the magnetic shield member 6 can be suppressed.

[0065] FIG. 6 is a perspective view showing the case 3 of the current sensor 1 (see FIG. 1). As shown in the figure, the case 3 has a shield hole 38 into which the end 6E (see FIG. 5) of the magnetic shield member 6 can be inserted without contacting the guide portion 32. That is, the case 3 has pairs of guide portions 32 (32a and 32b, and 32c and 32d, see FIG. 4) in the X direction. The guide portion 32 is formed as a wall-like body protruding in the Z direction, and on the opposite side of the wall-like body from the bus bar groove 31, the shield hole 38 into which the end 6E of the magnetic shield member 6 can be inserted without contacting the guide portion 32 is formed. The bus bar groove 31 and the shield hole 38 are connected via a gap 32D.

[0066] The case 3 is provided with a shielding hole 38, and when the bus bar 5 is sandwiched between the case 3 and the cover 4, the end 6E of the tip of the magnetic shield member 6 does not come into contact with the guide portion 32. Therefore, when positioning the case 3, the cover 4, and the bus bar 5, there is no interference between the case 3 and the magnetic shield member 6, and this interference does not affect assembly.

[0067] 7 is a plan view showing the positional relationship between the bus bar 5 and the magnetic shield member 6 in the current sensor 1. As shown in the drawing, the dimension W6 in the Y direction of the magnetic shield member 6 is smaller than the dimension W5 in the Y direction of the bus bar 5. In addition, the magnetic shield member 6 is arranged so as not to protrude from the bus bar 5 in the Y direction.

[0068] This configuration allows for miniaturization in the width direction because the magnetic shield member 6 is not significantly larger than the width of the bus bar 5. Therefore, it is possible to provide a current sensor 1 that is less susceptible to the influence of external magnetic fields and has excellent noise resistance.

[0069] Here, the dimension in the Y direction refers to the dimension of the widest part in the Y direction of each of the bus bar 5 and the magnetic shield member 6. Furthermore, the magnetic shield member 6 not protruding from the bus bar 5 means that when an imaginary line in the X direction shown by the dashed line in Fig. 7 is drawn that touches the widest part in the Y direction when viewed along the Z direction, the entire magnetic shield member 6 is located between the imaginary line.

[0070] Fig. 8 is a cross-sectional view of the current sensor 1 taken along the XZ plane at line B-B in Fig. 1. As shown in the figure, the current sensor 1 has screws 7 as a pair of holding members that hold the case 3, the cover 4, and the bus bar 5 together. The bus bar 5 has a pair of insertion holes 56 through which the screws 7 can be inserted. The pair of insertion holes 56 are located on both sides of the necked portion 55 of the bus bar 5 in the X direction.

[0071] The case 3 has screw hole bosses 35 that protrude in the Z direction from the board-facing surface 34 (see FIG. 6 ) at positions corresponding to the pair of insertion holes 56. The cover 4 has second insertion holes 44 through which screws 7 can be inserted. The screw hole bosses 35, the second insertion holes 44, and the insertion holes 56 are aligned, and the screws 7 are inserted from the cover 4 side. The screws 7 that pass through the second insertion holes 44 and the insertion holes 56 are then screwed into the screw hole bosses 35, and the case 3, cover 4, and bus bar 5 can be held together by the screws 7.

[0072] 8 and 1 , when viewed along the Z direction, the substrate 9 is located between the two screw hole bosses 35 in the X direction. When viewed along the Y direction, the substrate 9 is located closer to the substrate-facing surface 34 of the case 3 than the straight line L connecting the tip ends 35E of the two screw hole bosses 35.

[0073] With the above configuration, the screw hole bosses 35 protect the substrate 9 and ensure a distance for insulating the substrate 9 from the outside of the current sensor 1. In other words, even if an external component is disposed near the Z2 side, X1 side, or X2 side of the substrate 9 and the external component comes into contact with the current sensor 1 due to some malfunction, the risk of the external component coming into direct contact with the substrate 9 is reduced, and the creepage distance from the substrate 9 to the external component can be increased. This reduces the likelihood of damage to the substrate 9 or a short circuit with the wiring provided on the substrate 9. Therefore, there is no need to provide a component that covers the entire Z2 side of the substrate 9, and the height in the Z direction can be reduced, thereby reducing the height of the current sensor 1.

[0074] The cover 4 has a protrusion 45 and a bottom portion 46, which is the area other than the protrusion 45, on a bottom surface 43 opposite the bus bar facing surface 42 that faces the bus bar 5. A part of the magnetic shield member 6 is insert-molded inside the protrusion 45. The bottom portion 46 on the bottom surface 43 is provided with a second insertion hole 44 through which the screw 7 can be inserted.

[0075] The height H1 in the Z direction from the bottom 46 to the tip 45E of the protruding portion 45 is greater than the height H2 from the bottom 46 to the screw head 7E of the screw 7 inserted into the second insertion hole 44. In this way, the height H1 at which the protruding portion 45 of the cover 4, into which a portion of the magnetic shield member 6 is insert-molded, protrudes from the bottom 46 is greater than the height H2 at which the screw head 7E of the screw 7 protrudes from the bottom 46. Therefore, the protruding portion 45 protects the screw 7 and prevents the screw head 7E from coming into contact with other members. Furthermore, even when the case 3, cover 4, and bus bar 5 are held by the screw 7, the screw head 7E does not protrude beyond the tip 45E toward the Z1 side, which also leads to a lower profile of the current sensor 1.

[0076] 9 is a perspective view showing the appearance of the current sensor 1, as seen from the case 3 side. The substrate 9 has a case-facing surface 91 that faces the case 3 and an outer surface 92 that is the surface opposite the case-facing surface 91, and the magnetic detection unit 2 is mounted on the case-facing surface 91 (see FIGS. 8 and 1). The substrate 9 is provided on a substrate-facing surface 34 of the case 3 that is opposite the busbar-facing surface 33 that faces the busbar 5 (see FIG. 6). Because the magnetic detection unit 2 is disposed in the space between the substrate 9 and the case 3, it is unlikely that an external member or the like will directly collide with the magnetic detection unit 2.

[0077] 9, the substrate 9 has two notches 93. The case 3 has two engagement portions 36 protruding from the substrate-facing surface 34. By engaging the two notches 93 with the two engagement portions 36, the substrate 9 can be easily positioned relative to the case 3. Note that the number of notches 93 and engagement portions 36 may be one or three or more, but two is preferable from the viewpoint of ease and accuracy of positioning.

[0078] The case 3 has a wall portion 37 that protrudes in the Z direction from the board-facing surface 34 (see FIG. 6 ) so as to surround the periphery of the board 9. The wall portion 37 is provided so that the distance from the board-facing surface 34 to the outer surface 92, which is the back surface of the case-facing surface 91 of the board 9, is the same as the distance from the board-facing surface 34 to the wall portion end 37E of the wall portion 37 is equal to or greater than the distance from the board-facing surface 34 to the outer surface 92 of the board 9.

[0079] By providing a wall portion 37 surrounding the periphery of the substrate 9 on the case 3 to protect the substrate 9, the reliability of the current sensor 1 can be improved, such as by mitigating the impact when the current sensor 1 collides with the outside and preventing damage to the substrate 9.

[0080] The distance from the board-facing surface 34 to the wall end 37E of the wall 37 does not have to be constant throughout the entire wall 37, and a portion may be provided that is farther from the wall end 37E than other portions. For example, as shown in Fig. 9, a wall 37H may be provided in which the distance from the board-facing surface 34 to the wall end 37E of the wall 37 is farther from the board-facing surface 34 than other portions, so that the notch 93 and the engaging portion 36 are covered by the wall 37H when viewed along the Y direction. Providing the wall 37H reduces the risk of the notch 93 and the engaging portion 36 coming into contact with the outside.

[0081] The current sensor 1 has three fixing portions 8 that fix the substrate 9 to the case 3. By providing three fixing portions 8, it is possible to reliably prevent misalignment between the case 3 and the substrate 9. This makes it possible to prevent deterioration of the measurement accuracy of the current sensor 1 due to misalignment between the two. Note that the fixing portions 8 can be configured by, for example, screwing, heat crimping, metal crimping, brace fitting, soldering, etc.

[0082] 10 is a perspective view showing the appearance of the current sensor 1 as seen from the cover 4 side. As shown in the figure, the cover 4 has a partition wall 47 that protrudes in the Z direction from the bottom 46 and extends in the X direction. By providing the partition wall 47 in addition to the protruding part 45, stability is improved when the cover 4 of the current sensor 1 is placed with the protruding part 45 facing downward. Furthermore, contact of the screw head 7E with other components can be prevented, improving the insulation of the screw 7.

[0083] In the current sensor 1, the partitions 47 are disposed on both sides in the Y direction of the second insertion hole 44. By providing the partitions 47 on both sides of the second insertion hole 44, the screw 7 is protected from three directions and the screw head 7E can be prevented from coming into contact with other members.

[0084] In the cover 4, the height H3 of the partition wall 47 from the bottom 46 is the same as the height H4 of the protrusion 45 from the bottom 46 in the Z direction. With this configuration, there is no step between the partition wall 47 and the protrusion 45, improving stability when the cover 4 of the current sensor 1 is placed with the protrusion 45 facing downward.

[0085] 11 is a perspective view showing the appearance of a modified example of the current sensor 1. In the figure, the position of the magnetic detection unit 2 provided on the substrate 9 is indicated by a dashed line. As indicated by the dashed line in the figure, when viewed from the Z direction, the current sensor 1 has the fixed portion 8 provided at a position where a right triangle is formed by three straight lines connecting the fixed portions 8. The opposite side and the adjacent side of the right triangle that intersect at a right angle are each parallel to the X direction or the Y direction, and the hypotenuse opposite the right angle of the right triangle overlaps with a part of the magnetic detection unit 2.

[0086] Of the protruding portions 57a and 57b of the bus bar 5 that protrude from both sides of the case 3 in the X direction, one of the protruding portions 57b (on the X2 side) has a bent portion 58. Of the three fixing portions 8, two fixing portions 8 are provided in a region closer to the bent portion 58 than to the center 94 of the substrate 9 in the X direction.

[0087] With the above configuration, even if stress is applied to the bus bar 5 in a direction that twists or bends the bus bar 5 when fastening the bus bar 5 to an external terminal or the like, and stress is also applied to the case 3 via the bus bar 5, the substrate 9 can be stably fixed to the case 3. That is, because two fixing portions 8 are provided in an area close to the protruding portion 57b having the bent portion 58 of the bus bar 5, if deformation occurs in a portion of the case 3 close to the bent portion 58 when fastening the bus bar 5, the force caused by the deformation can be dispersed. Therefore, even if the bus bar 5 has the bent portion 58, the substrate 9 can be stably fixed to the case 3.

[0088] 12 is a partial cross-sectional view of a portion corresponding to A-A in FIG. 1 , taken along the XY plane near the surface of the busbar 5 of the current sensor 1, in a modified example different from that shown in FIG. 10 . As shown in the figure, a busbar 5 may be used in which the notch 54 is provided only on one side of the constricted portion 55. In this case, as shown in FIG. 12 , a configuration may be provided in which one guide portion 32 having the first reference surface S1 and one support portion 41 having the second reference surface S2 are provided. Even with this configuration, the case 3, cover 4, and busbar 5 can be positioned with high precision, similar to the configurations of the case 3 and cover 4 shown in FIGS. 3 and 4 .

[0089] The busbar 5 of Figure 12, in which the notch 54 is provided only on one side of the constricted portion 55, is advantageous over the busbars 5 shown in Figures 3 and 4, in which the notch 54 is provided on both sides of the constricted portion 55, in that it has a simpler structure.

[0090] However, from the viewpoints of ease of assembly and miniaturization, the bus bar 5 shown in Figures 3 and 4, in which the notches 54 are provided on both sides of the constricted portion 55, is preferable. In other words, simply placing the bus bar 5 in the bus bar groove 31 in Figure 12 makes the bus bar 5 prone to movement in the X direction, resulting in poor assembly. Furthermore, if the magnetic shield member 6 is placed as in Figures 3 and 4, a portion of the magnetic shield member 6 will be placed outside the bus bar 5 on the Y2 side, making it difficult to miniaturize the bus bar 5 in the Y direction.

[0091] In the above-described embodiment, the present invention has been described as being embodied as a current sensor 1 including a busbar 5. However, the present invention can also be embodied as a current sensor 1 that does not include a busbar 5, that is, a current sensor that includes a magnetic detection unit 2, a case 3, and a cover 4, but does not include a busbar 5, and in which the busbar 5 is held between the case 3 and the cover 4. Even when the present invention is embodied in this manner, positioning is performed by pressing the first reference surface S1 of the case 3 and the second reference surface S2 of the cover 4 against the third reference surface S3, which is the end surface 53 in the width direction of the busbar 5 attached to the current sensor 1. This allows the case 3 and the cover 4 to be positioned accurately when attaching the busbar 5.

[0092] The embodiments disclosed in this specification are illustrative in all respects and are not limited to these embodiments. The scope of the present invention is defined by the claims rather than by the description of the above-described embodiments alone, and is intended to include all modifications within the meaning and scope of the claims.

[0093] The present invention is useful as a current sensor for measuring a current to be measured flowing through equipment, for example, in order to control a power supply system of a vehicle or the like equipped with various equipment.

[0094] DESCRIPTION OF SYMBOLS 1: Current sensor 2: Magnetic detection unit 3: Case 31: Bus bar groove 321: First convex portion 323: Third convex portion 32: Guide portion 32D: Gap 32a: Guide portion 32b: Guide portion 32c: Guide portion 32d: Guide portion 33: Bus bar facing surface 34: Board facing surface 35: Screw hole boss 35E: Tip portion 36: Engagement portion 37: Wall portion 37E: Wall portion end 37H: Wall portion 38: Shield hole 4: Cover 41: Support portion 41a: Support portion 41b: Support portion 412: Second convex portion 42: Bus bar facing surface 43: Bottom surface 44: Second insertion hole 45: Protrusion 45E : Tip 46 : Bottom 47 : Partition portion 5 : Bus bar 51 : Opposing surface 52 : Plate-shaped portion 53 : End surface 54 : Notch portion 54S : X-opposing surface 55 : Narrowed portion 56 : Insertion hole 57a : Protruding portion 57b : Protruding portion 58 : Bent portion 6 : Magnetic shielding member 6E : End portion 7 : Screw 7E : Screw head 8 : Fixing portion 9 : Board 91 : Case-opposing surface 92 : Outer surface 93 : Notch portion 94 : Center H1 : Height H2 : Height H3 : Height H4 : Height S1 : First reference surface S2 : Second reference surface S3 : Third reference surface SP : Pressing surface W5 : Dimension W6 : Dimension L : Straight line

Claims

1. It comprises a magnetic detection unit, a case, a cover, and a busbar. The busbar has a plate-like portion that extends in the X direction, among the mutually orthogonal X, Y, and Z directions, with the Z direction as the normal direction and facing the magnetic detection unit, and a surface facing the magnetic detection unit is formed therein. In a current sensor in which the plate-shaped portion of the busbar having the opposing surface is held between the case and the cover from both sides in the Z direction, The case has a first reference surface, the cover has a second reference surface, and the busbar has a third reference surface. The case, the cover, and the busbar are positioned by pressing the first reference surface and the second reference surface against the third reference surface. The third reference surface is the end face in the Y direction of the plate-like portion of the busbar, The bus bar has a constricted portion with a notch recessed in the Y direction, The third reference plane is one of the end faces of the constricted portion in the Y direction, The case has a groove for a busbar on the surface facing the cover, on which the busbar can be positioned. The groove for the bus bar is provided with a guide portion that protrudes in the Y direction when viewed along the Z direction. The guide portion is inserted into the notch and has a first reference surface at a location facing the third reference surface. The aforementioned notch has X-facing surfaces that face each other in the X direction, Of the two guide portions that are paired in the X direction, A third protrusion is formed on one of the guide portions, projecting in the X direction from the surface facing the X-facing surface. The other surface of the guide portion facing the other opposing surface and the other opposing surface of the notch portion are in contact. A current sensor characterized in that the third protrusion is in pressure contact with one of the opposing surfaces.

2. Having a magnetic detection unit, a case, a cover, and a busbar, The busbar has a plate-like portion that extends in the X direction, among the mutually orthogonal X, Y, and Z directions, with the Z direction as the normal direction and facing the magnetic detection unit, and a surface facing the magnetic detection unit is formed therein. In a current sensor in which the plate-shaped portion of the busbar having the opposing surface is held between the case and the cover from both sides in the Z direction, The case has a first reference surface, the cover has a second reference surface, and the busbar has a third reference surface. The case, the cover, and the busbar are positioned by pressing the first reference surface and the second reference surface against the third reference surface. The third reference surface is the end face in the Y direction of the plate-like portion of the busbar, The bus bar has a constricted portion with a notch recessed in the Y direction, The third reference plane is one of the end faces of the constricted portion in the Y direction, The case has a groove for a busbar on the surface facing the cover, on which the busbar can be positioned. The groove for the bus bar is provided with a guide portion that protrudes in the Y direction when viewed along the Z direction. The guide portion is inserted into the notch and has a first reference surface at a location facing the third reference surface. The cover has a support column that protrudes in the Z direction from the surface facing the case, The guide portion and the support portion are inserted into and fitted into the notched portion. The support column has the second reference surface at a location opposite to the third reference surface, It has a U-shaped magnetic shielding member, The magnetic shielding member is insert-molded into the cover, with both ends protruding from the surface of the cover facing the busbar. Each of the pair of support columns is positioned between the ends of the magnetic shielding member, in contact with the magnetic shielding member. A current sensor characterized in that, when viewed from the case side to the cover side along the Z-axis, the magnetic detection unit is positioned between the ends of the magnetic shielding member.

3. The current sensor according to claim 2, wherein the case has a shielding hole into which the end of the magnetic shielding member can be inserted without contacting the guide portion.

4. The dimension of the magnetic shielding member in the Y direction is smaller than the dimension of the busbar in the Y direction. The current sensor according to claim 2, wherein the magnetic shielding member is arranged so as not to protrude from the busbar in the Y direction.

5. Having a magnetic detection unit, a case, a cover, and a busbar, The busbar has a plate-like portion that extends in the X direction, among the mutually orthogonal X, Y, and Z directions, with the Z direction as the normal direction and facing the magnetic detection unit, and a surface facing the magnetic detection unit is formed therein. In a current sensor in which the plate-shaped portion of the busbar having the opposing surface is held between the case and the cover from both sides in the Z direction, The case has a first reference surface, the cover has a second reference surface, and the busbar has a third reference surface. The case, the cover, and the busbar are positioned by pressing the first reference surface and the second reference surface against the third reference surface. The third reference surface is the end face in the Y direction of the plate-like portion of the busbar, The bus bar has a constricted portion with a notch recessed in the Y direction, The third reference plane is one of the end faces of the constricted portion in the Y direction, The case has a groove for a busbar on the surface facing the cover, on which the busbar can be positioned. The groove for the bus bar is provided with a guide portion that protrudes in the Y direction when viewed along the Z direction. The guide portion is inserted into the notch and has a first reference surface at a location facing the third reference surface. The cover has a support column that protrudes in the Z direction from the surface facing the case, The guide portion and the support portion are inserted into and fitted into the notched portion. The support column has the second reference surface at a location opposite to the third reference surface, Two of the aforementioned guide portions are provided spaced apart in the X direction, with a gap in between them. The aforementioned support column fits into the gap, Two paired guide portions and support portions in the X direction are fitted into the notch portion. The busbar has the notches on both sides of the plate-like portion in the Y direction, The case has two guide portions that are paired in the X direction and correspond to the two notches, The cover has two support columns corresponding to the two notches, In one of the notches, the end face of the constricted portion is the third reference surface, the guide portion that fits into one of the notches has the first reference surface, and the support portion that fits into the gap between two pairs of guide portions in the X direction that fit into one of the notches has the second reference surface. The other end face in the constricted portion, opposite to the end face having the third reference surface, is a pressing surface. Each of the guide portions facing the pressing surface has a first protrusion projecting in the Y direction on the surface facing the pressing surface, The support column portion has a second protrusion projecting in the Y direction on the surface facing the pressing surface, The current sensor is characterized in that the first and second protrusions are in pressure contact with the pressing surface.

6. Having a magnetic detection unit, a case, a cover, and a busbar, The busbar has a plate-like portion that extends in the X direction, among the mutually orthogonal X, Y, and Z directions, with the Z direction as the normal direction and facing the magnetic detection unit, and a surface facing the magnetic detection unit is formed therein. In a current sensor in which the plate-shaped portion of the busbar having the opposing surface is held between the case and the cover from both sides in the Z direction, The case has a first reference surface, the cover has a second reference surface, and the busbar has a third reference surface. The case, the cover, and the busbar are positioned by pressing the first reference surface and the second reference surface against the third reference surface. The third reference surface is the end face in the Y direction of the plate-like portion of the busbar, The bus bar has a constricted portion with a notch recessed in the Y direction, The third reference plane is one of the end faces of the constricted portion in the Y direction, The case, the cover, and the busbar are integrally held by a pair of retaining members, The busbar has a pair of insertion holes through which the retaining member can be inserted, The pair of aforementioned insertion holes are arranged on both sides of the constricted portion in the X direction, The retaining member is a screw, The magnetic detection unit is mounted on the case-facing surface of the substrate, which faces the case. The substrate is provided on the substrate-facing surface of the case opposite to the busbar-facing surface that faces the busbar, The substrate is provided with the notched portion, The case is provided with an engaging portion that protrudes from the surface facing the substrate, The engagement between the notch and the engaging portion positions the substrate relative to the case. The cover has a second insertion hole through which the screw can be inserted. The case has a boss for a screw hole that protrudes in the Z direction from the surface facing the substrate, When viewed along the Z direction, the substrate is positioned between the two screw hole bosses in the X direction. When viewed along the Y direction, the substrate is positioned closer to the surface of the case facing the substrate than to the straight line connecting the tips of the two screw hole bosses. The substrate is provided with three fixing parts for fixing it to the cover, When viewed from the Z direction, A right-angled triangle is formed by the three straight lines connecting the aforementioned fixing parts. In the aforementioned right-angled triangle, opposite sides and adjacent sides that intersect at a right angle are parallel to the X direction or the Y direction, A current sensor characterized in that the hypotenuse opposite the right angle of the right triangle overlaps with a part of the magnetic detection unit.

7. Of the protruding parts of the busbar that protrude from both sides of the case, one has a bent portion. The current sensor according to claim 6, wherein two of the three fixing portions are provided in a region closer to the bent portion than to the center of the substrate in the X direction.

8. The case has a groove for a busbar on the surface facing the cover, on which the busbar can be positioned. The groove for the bus bar is provided with a guide portion that protrudes in the Y direction when viewed along the Z direction. The current sensor according to claim 6, wherein the guide portion is inserted into the notch and has a first reference surface at a location facing the third reference surface.

9. The cover has a support column that protrudes in the Z direction from the surface facing the case, The guide portion and the support portion are inserted into and fitted into the notched portion. The current sensor according to claim 1 or claim 8, wherein the support column has the second reference surface at a location facing the third reference surface.

10. Two of the aforementioned guide portions are provided spaced apart in the X direction, with a gap in between them. The aforementioned support column fits into the gap, The current sensor according to claim 9, wherein two paired guide portions and support portions in the X direction fit into the notch.

11. The busbar has the notches on both sides of the plate-like portion in the Y direction, The case has two guide portions that are paired in the X direction and correspond to the two notches, The cover has two support columns corresponding to the two notches, The current sensor according to claim 10, wherein the end face of the constricted portion in one of the notches is the third reference surface, the guide portion that fits into one of the notches has the first reference surface, and the support portion that fits into the gap between two paired guide portions in the X direction that fit into one of the notches has the second reference surface.

12. The other end face in the constricted portion, opposite to the end face having the third reference surface, is a pressing surface. Each of the guide portions facing the pressing surface has a first protrusion projecting in the Y direction on the surface facing the pressing surface, The support column portion has a second protrusion projecting in the Y direction on the surface facing the pressing surface, The current sensor according to claim 11, wherein the first protrusion and the second protrusion are in pressure contact with the pressing surface.

13. The case, the cover, and the busbar are integrally held by a pair of retaining members, The busbar has a pair of insertion holes through which the retaining member can be inserted, The current sensor according to any one of claims 1 to 5, wherein the pair of insertion holes are arranged on both sides of the constricted portion in the X direction.

14. The current sensor according to claim 13, wherein the retaining member is a screw.

15. The magnetic detection unit is mounted on the case-facing surface of the substrate, which faces the case. The substrate is provided on the substrate-facing surface of the case opposite to the busbar-facing surface that faces the busbar, The substrate is provided with the notched portion, The case is provided with an engaging portion that protrudes from the surface facing the substrate, The current sensor according to claim 14, wherein the substrate is positioned relative to the case by engagement between the notch and the engaging portion.

16. The cover has a second insertion hole through which the screw can be inserted. The case has a boss for a screw hole that protrudes in the Z direction from the surface facing the substrate, When viewed along the Z direction, the substrate is positioned between the two screw hole bosses in the X direction. The current sensor according to claim 15, wherein, when viewed along the Y direction, the substrate is located closer to the substrate-facing surface of the case than the straight line connecting the tips of the two screw hole bosses.

17. The case has a wall portion that protrudes in the Z direction from the surface facing the substrate so as to surround the substrate, The current sensor according to claim 16, wherein the wall portion protrudes to a position at least equal to the back surface of the substrate facing the substrate.

18. The cover has a protrusion on the bottom surface opposite to the busbar-facing surface that faces the busbar, and a bottom surface which is the area other than the protrusion. The protruding portion has a magnetic shielding member that is partially insert-molded inside, A second insertion hole through which the screw can be inserted is provided in the bottom portion of the bottom surface. The current sensor according to claim 14, wherein the height from the bottom to the tip of the protrusion in the Z direction is greater than the height from the bottom to the head of the screw inserted into the second insertion hole.

19. The current sensor according to claim 18, wherein the cover has a partition wall portion that protrudes from the bottom in the Z direction and extends in the X direction.

20. The current sensor according to claim 19, wherein the partition wall portion is arranged on both sides of the second insertion hole in the Y direction.

21. The current sensor according to claim 20, wherein the height of the partition wall portion from the bottom and the height of the protrusion portion from the bottom of the bottom surface are the same in the Z direction.

22. The case has a wall portion that protrudes in the Z direction from the surface facing the substrate so as to surround the substrate, The current sensor according to claim 6, wherein the wall portion protrudes to a position at least equal to the back surface of the substrate facing the substrate.

23. The cover has a protrusion on the bottom surface opposite to the busbar-facing surface that faces the busbar, and a bottom surface which is the area other than the protrusion. A portion of the magnetic shielding member is insert-molded inside the aforementioned protrusion. The second insertion hole is provided at the bottom of the bottom surface, The current sensor according to claim 6, wherein the height from the bottom to the tip of the protrusion in the Z direction is greater than the height from the bottom to the head of the screw inserted into the second insertion hole.

24. The current sensor according to claim 23, wherein the cover has a partition wall portion that protrudes from the bottom in the Z direction and extends in the X direction.

25. The current sensor according to claim 24, wherein the partition wall portion is arranged on both sides of the second insertion hole in the Y direction.

26. The current sensor according to claim 25, wherein the height of the partition wall portion from the bottom and the height of the protrusion portion from the bottom of the bottom surface are the same in the Z direction.